.rs .\" Troff code generated by TPS Convert from ITU Original Files .\" Not Copyright ( c) 1991 .\" .\" Assumes tbl, eqn, MS macros, and lots of luck. .TA 1c 2c 3c 4c 5c 6c 7c 8c .ds CH .ds CF .EQ delim @@ .EN .nr LL 40.5P .nr ll 40.5P .nr HM 3P .nr FM 6P .nr PO 4P .nr PD 9p .po 4P .rs \v | 5i' .LP \fBMONTAGE: FIN DU \(sc 7.2 EN\(hyT\* | TE DE CETTE PAGE\fR .IP \v'13P' \fB7.3\ Principal characteristics of primary multiplex equipment\fR .sp 1P .RT .sp 2P .LP \fBRecommendation\ G.731\fR .RT .sp 2P .sp 1P .ce 1000 \fBPRIMARY\ PCM\ MULTIPLEX\ EQUIPMENT\ FOR\ VOICE\ FREQUENCIES\fR .EF '% Fascicle\ III.4\ \(em\ Rec.\ G.731'' .OF '''Fascicle\ III.4\ \(em\ Rec.\ G.731 %' .ce 0 .sp 1P .ce 1000 \fI(Geneva, 1972; further amended)\fR .sp 9p .RT .ce 0 .sp 1P .LP The\ CCITT, .sp 1P .RT .sp 1P .LP \fIconsidering\fR .sp 9p .RT .PP that pulse code modulation (PCM) multiplex equipments are already used in various countries, in particular to provide a large number of short\(hydistance telephone circuits on certain pairs in existing cables, and in order to minimize the number of different PCM multiplex equipments providing circuits which may be used in international connections, .sp 1P .LP \fIrecommends\fR .sp 9p .RT .PP that Administrations concerned should make their choice between the two primary PCM multiplex equipments described in Recommendations\ G.732 and\ G.733. .sp 2P .LP \fBRecommendation\ G.732\fR .RT .sp 2P .ce 1000 \fBCHARACTERISTICS\ OF\fR \ \fBPRIMARY\ PCM\ MULTIPLEX\ EQUIPMENT\fR .EF '% Fascicle\ III.4\ \(em\ Rec.\ G.732'' .OF '''Fascicle\ III.4\ \(em\ Rec.\ G.732 %' .ce 0 .sp 1P .ce 1000 \fBOPERATING\ AT\ 2048\ kbit/s\fR .ce 0 .sp 1P .ce 1000 \fI(Geneva, 1972; further amended)\fR .sp 9p .RT .ce 0 .sp 1P .LP \fB1\fR \fBGeneral characteristics\fR .sp 1P .RT .sp 1P .LP 1.1 \fIFundamental characteristics\fR .sp 9p .RT .PP The encoding law used is the A\(hylaw as specified in Recommendation\ G.711. The sampling rate, load capacity and the code are also specified in that Recommendation. .PP The number of quantized values is 256. .PP \fINote\fR \ \(em\ The inversion of bits\ 2, 4, 6, and\ 8 is covered by the encoding law and is applicable only to voice\(hychannel time slots. .bp .RT .sp 1P .LP 1.2 \fIBit rate\fR .sp 9p .RT .PP The nominal bit rate is 2048\ kbit/s. The tolerance on this rate is \(+- | 0\ parts per million (ppm). .RT .sp 1P .LP 1.3 \fITiming signal\fR .sp 9p .RT .PP It should be possible to derive the transmitting timing signal of a PCM multiplex equipment from an internal source, from the incoming digital signal and also from an external source. .PP \fINote\fR \ \(em\ Further study is required on the effect of jitter of the incoming signal on the timing signal, and on the measures to be taken in case of loss of the incoming signal or the external source. .RT .sp 2P .LP \fB2\fR \fBFrame structure\fR .sp 1P .RT .PP Refer to \(sc\(sc\ 3.3.1 and 3.3.2 of Recommendation\ G.704 for frame structure and use of derived channel time slots. .PP \fINote\fR \ \(em\ If channel time slot\ 16 which is assigned to signalling as covered in \(sc\ 5 below is not needed for signalling it may be used for purposes other than a voice channel encoded within the PCM multiplex equipment. .RT .sp 2P .LP \fB3\fR \fBLoss and recovery of frame alignment\fR .sp 1P .RT .PP The strategy for the loss and recovery of frame alignment should be according to Recommenda tion\ G.706, \(sc\ 4.1. .RT .sp 2P .LP \fB4\fR \fBFault conditions\fR \fBand consequent actions\fR .sp 1P .RT .sp 1P .LP 4.1 \fIFault conditions\fR .sp 9p .RT .PP The PCM multiplex equipment should detect the following fault conditions: .RT .PP 4.1.1 Failure of power supply. .sp 9p .RT .PP 4.1.2 Failure of codec (except when using single\(hychannel codecs). .sp 9p .RT .PP As a minimum requirement this fault condition should be recognized when, for at least one signal level in the range \(em21 to\ \(em6\ dBm0, the signal\(hyto\(hyquantizing noise ratio performance of the local codec is 18\ dB or more below the level recommended in Recommendation\ G.712. .PP 4.1.3 Loss of incoming signal at the 64\ kbit/s input port (time slot\ 16). .sp 9p .RT .PP \fINote\ 1\fR \ \(em\ The detection of this fault condition is not mandatory when channel associated signalling is used and the signalling multiplex is situated within a few metres of the PCM multiplex equipment. .PP \fINote\ 2\fR \ \(em\ The detection of this fault condition is not mandatory when contradirectional interfaces are used. .RT .PP 4.1.4 Loss of the incoming signal at 2048\ kbit/s. .sp 9p .RT .PP \fINote\fR \ \(em\ The detection of this fault condition is required only when it does not result in an indication of loss of frame alignment. .PP 4.1.5 Loss of frame alignment. .sp 9p .RT .PP 4.1.6 Excessive bit error ratio detected by monitoring the frame alignment signal. .sp 9p .RT .PP 4.1.6.1 With a random bit error ratio of \(= | 0\uD\dlF261\u4\d, the probabiliy of activating the indication of fault condition within a few seconds should be less than\ 10\uD\dlF261\u6\d. .sp 9p .RT .PP With a random bit error ratio of \(>=" | 0\uD\dlF261\u3\d, the probability of activating the indication of fault condition within a few seconds should be higher than\ 0.95. .bp .PP 4.1.6.2 With a random bit error ratio of \(>=" | 0\uD\dlF261\u3\d, the probability of deactivating the indication of fault condition within a few seconds should be almost\ 0. .sp 9p .RT .PP With a random bit error ratio of \(= | 0\uD\dlF261\u4\d, the probability of deactivating the indication of fault condition within a few seconds should be higher than\ 0.95. .PP \fINote\fR \ \(em\ The activating and the deactivating period specified as \*Qa few seconds\*U is intended to be in the order of 4 to\ 5 seconds. .RT .PP 4.1.7 Alarm indication received from the remote PCM multiplex equipment (see \(sc\ 4.2.3 below). .sp 9p .RT .sp 1P .LP 4.2 \fIConsequent actions\fR .sp 9p .RT .PP Further to the detection of a fault condition, appropriate actions should be taken as specified in Table\ 1/G.732. The consequent actions are as follows: .RT .PP 4.2.1 Service alarm indication generated to signify that the service provided by the PCM multiplex is no longer available. This indication should be forwarded at least to the switching and/or signalling multiplex equipment depending upon the arrangements provided. The indication should be given as soon as possible and not later than 2\ ms after detection of the relevant fault condition. .sp 9p .RT .PP This specification, taking into account the specification given in \(sc\ 3 above, is equivalent to recommending that the average time to detect a loss of frame alignment and to give the relevant indication should not be greater than 3\ ms. .PP When using common\(hychannel signalling, the indication should be forwarded to the switching equipment by means of a separate interface on the PCM multiplex equipment. .RT .PP 4.2.2 Prompt maintenance alarm indication generated to signify that performance is below acceptable standards and maintenance attention is required locally. When the Alarm Indication Signal (AIS) (see General Notes below to \(sc\ 4.2) is detected, the prompt maintenance alarm indication associated with loss of frame alignment (see \(sc\ 4.1.5 above) and excessive error ratio (see \(sc\ 4.1.6 above) should be inhibited, while the rest of the consequent actions are in accordance with those associated in Table\ 1/G.732 with the two fault conditions. .sp 9p .RT .PP \fINote\fR \ \(em\ The location and provision of any visual and/or audible alarm activated by the alarm indications given in \(sc\(sc\ 4.2.1 and\ 4.2.2 above, is left to the discretion of each Administration. .PP 4.2.3 Alarm indication to the remote end, transmitted by changing bit\ 3 of channel time\(hyslot 0 from the state\ 0 to the state\ 1 in those frames not containing the frame alignment signal. This should be effected as soon as possible. .sp 9p .RT .PP 4.2.4 Transmission suppressed at the analogue outputs. .sp 9p .RT .PP 4.2.5 AIS applied to time\(hyslot 16\ 64 kbit/s output (see General Notes below to \(sc\ 4.2). This action should be taken as soon as possible and not later than 2\ ms after the detection of the fault condition. .sp 9p .RT .PP 4.2.6 AIS applied to time slot\ 16 of the output 2048\ kbit/s composite signal (if supervision of the incoming 64\ kbit/s signal is provided). .sp 9p .RT .sp 1P .LP \fIGeneral Notes to \(sc\ 4.2\fR .sp 9p .RT .PP \fINote\ 1\fR \ \(em\ Yhe equivalent binary content of the AIS is a continuous stream of binary 1s. The strategy for detecting the presence of the AIS should be such that the AIS is detectable, even in the presence of an error ratio of 1 | (mu | 0\uD\dlF261\u3\d. However, a signal with all bits except the frame alignment in the 1\ state, should not be mistaken as an\ AIS. .PP \fINote\ 2\fR \ \(em\ All timing requirements quoted apply equally to restoration, subsequent to the fault condition clearing. .RT .sp 2P .LP \fB5\fR \fBSignalling\fR .sp 1P .RT .sp 1P .LP 5.1 \fISignalling arrangement\fR .sp 9p .RT .PP Refer to \(sc\ 3.3.3 of Recommendation G.704. Channel time slot\ 16 may be used to provide an interface at 64\ kbit/s which shall be suitable for use with either common channel or channel associated signalling. .bp .RT .ce \fBH.T. [T1.732]\fR .ce TABLE\ 1/G.732 .ce \fBFault conditions and consequent actions for the\fR .ce \fBPCM multiplex equipment\fR .ps 9 .vs 11 .nr VS 11 .nr PS 9 .TS center box; cw(30p) | cw(36p) | cw(30p) sw(24p) sw(30p) sw(24p) sw(30p) sw(24p) , ^ | ^ | c | c | c | c | c | c. Equipment part { Fault conditions (see \(sc\ 4.1) } { Consequent actions (see \(sc\ 4.2) } { Service alarm indication generated } { Prompt maitenance alarm indication generated } { Alarm indication to the remote end transmitted } { Transmission suppressed at the analogue outputs } { AIS applied to 64\ kbit/s output (time slot\ 16) } { AIS applied to time slot 16 of the 2048\ kbit/s composite signal } _ .T& lw(30p) | lw(36p) | cw(30p) | cw(24p) | cw(30p) | cw(24p) | cw(30p) | cw(24p) , ^ | l | c | c | c | c | l | l. { Multiplexer and demulti plexer } Failure of power supply Yes Yes Yes (if practicable) Yes (if practicable) Yes (if practicable) Yes (if practicable) Failure of codec Yes Yes Yes Yes _ .T& lw(30p) | lw(36p) | cw(30p) | cw(24p) | cw(30p) | cw(24p) | cw(30p) | cw(24p) , ^ | l | c | c | c | c | l | l. Multiplexer only { Loss of incoming signal at 64\ kbit/s input time slot 16 (see Notes under \(sc\ 4.1.3) } Yes Yes _ .T& lw(30p) | lw(36p) | cw(30p) | cw(24p) | cw(30p) | cw(24p) | cw(30p) | lw(24p) , ^ | c | c | c | c | c | l | c ^ | c | c | c | c | l | l | l ^ | l | l | l | l | l | l | l. Demulti plexer\ only { Loss of incoming signal at 2048\ kbit/s } Yes Yes Yes Yes Yes Loss of trame alignment Yes Yes Yes Yes Yes { Error ratio 10\uD\dlF261\u3\d on the frame alignment signal } Yes Yes Yes Yes Yes .TE .LP Alarm indication received from the remote end (bit\ 3 of\ time slot\ 0) Yes \fINote\fR \ \(em\ A \fIYes\fR | n the table signifies that an action should be taken as a consequence of the relevant fault condition. An \fIopen space\fR | in the table signifies that the relevant action should \fInot\fR be taken as a consequence of the relevant fault condition, if this condition is the only one present. If more than one fault condition is simultaneously present the relevant action should be taken if, for at least one of the conditions, a \fIYes\fR is defined in relation to this action. .nr PS 9 .RT .ad r \fBTable 1/G.732 [T1.732], p.\fR .sp 1P .RT .ad b .RT .LP .bp .sp 1P .LP 5.2 \fILoss and recovery of multiframe alignment in case of\fR \fIchannel\fR \fIassociated signalling\fR .sp 9p .RT .PP Multiframe alignment should be assumed to have been lost when two consecutive multiframe alignment signals have been received with an error. .PP Multiframe alignment should be assumed to have been recovered as soon as the first correct multiframe alignment signal is detected. .PP \fINote\fR \ \(em\ To avoid a condition of spurious multiframe alignment, the following procedure may be used in addition to the above: .RT .LP \(em Multiframe alignment should be assumed to have been lost when, for a period of one or two multiframes, all the bits in time slot\ 16 are in state\ 0. .LP \(em Multiframe alignment should be assumed to have been recovered only when at least one bit in state\ 1 is present in the time slot\ 16 preceding the multiframe alignment signal first detected. .sp 2P .LP 5.3 \fIFault conditions and consequent actions in case of channel\fR \fIassociated signalling\fR .sp 1P .RT .sp 1P .LP 5.3.1 \fIFault conditions\fR .sp 9p .RT .PP The signalling multiplex equipment should detect the following fault conditions: .RT .PP 5.3.1.1\fR Failure of power supply. .sp 9p .RT .PP 5.3.1.2 Loss of 64\ kbit/s incoming signal at the input of the signalling demultiplexer. .sp 9p .RT .PP \fINote\ 1\fR \ \(em\ The detection of this fault condition is not mandatory when the signalling multiplex equipment is situated within a few metres of the PCM multiplex equipment or when this fault condition results in an indication of loss of multiframe alignment. .PP \fINote\ 2\fR \ \(em\ Where separate circuits are used for the digital signal and the timing signal then loss of either or both should constitute loss of the incoming signal. .RT .PP 5.3.1.3\fR Loss of multiframe alignment. .sp 9p .RT .PP 5.3.1.4 Alarm indication received from the remote signalling multiplex equipment (see \(sc\ 5.3.2.3 below). .sp 9p .RT .PP 5.3.1.5 Receipt of the service alarm indication from the PCM multiplex equipment (see \(sc\ 4.2.1 above). .sp 9p .RT .sp 1P .LP 5.3.2 \fIConsequent actions\fR .sp 9p .RT .PP Further to the detection of a fault condition appropriate actions should be taken as specified in Table\ 2/G.732. The consequent actions are as follows: .RT .PP 5.3.2.1\fR Service alarm indication to be forwarded to the switching equipment depending upon the switching and signalling arrangements provided. .sp 9p .RT .PP 5.3.2.2\fR Prompt maintenance alarm indication generated to signify that performance is below acceptable standards and maintenace attention is required locally. If provision is made for detecting the AIS, then on the reception of the AIS, the prompt maintenance alarm indication should be inhibited in the case of loss of multiframe (see \(sc\ 5.3.1.3 above). .sp 9p .RT .PP \fINote\fR \ \(em\ The location and provision of any visual and or audible alarms activated by the alarm indications given in \(sc\(sc\ 5.3.2.1 and\ 5.3.2.2 above is left to the discretion of each Administration. .PP 5.3.2.3\fR Alarm indication to the remote signalling multiplex equipment, generated by changing from the state\ 0 to the state\ 1 bit\ 6 of channel time slot\ 16 of frame\ 0 of the multiframe (see Table\ 7/G.704); this should be effected as soon as possible. .sp 9p .RT .PP 5.3.2.4\fR Application of the condition corresponding to state\ 1 on the line to all receive signalling channels. This condition should be forwarded as soon as possible and not later than 3\ ms after the detection of the fault condition. .sp 9p .RT .PP \fINote\fR \ \(em\ All timing requirements quoted apply equally to restoration, subsequent to the fault condition clearing. .bp .sp 2P .LP \fB6\fR \fBInterfaces\fR .sp 1P .RT .PP The analogue interfaces should be in accordance with Recommendations\ G.712, G.713, G.714 and\ G.715. The digital interfaces at 2048\ kbit/s should be in accordance with Recommendation\ G.703. The digital interfaces at 64\ kbit/s should be of either the codirectional or the contradirectional type specified in Recommendation\ G.703. The specifications for 64\ kbit/s interfaces are not mandatory for channel associated signalling. The interface for external synchronization of the transmitting timing signal should be in accordance with Recommendation\ G.703. .RT .ce \fBH.T. [T2.732]\fR .ce TABLE\ 2/G.732 .ce \fBFault conditions and consequent actions for .ce channel\(hyassociated\fR .ce \fBsignalling multiplex equipment\fR .ps 9 .vs 11 .nr VS 11 .nr PS 9 .TS center box; cw(36p) | cw(54p) | cw(30p) sw(30p) sw(30p) sw(48p) , ^ | ^ | c | c | c | c. Equipment part { Fault conditions (see \(sc 5.3.1) } { Consequent actions (see \(sc 5.3.2) } { Service alarm indication generated } { Prompt maintenance alarm indication generated } { Alarm indication to the remote end transmitted } { Application of state, equivalent to state 1, on line to all receive signalling channels } _ .T& lw(36p) | lw(54p) | cw(30p) | cw(30p) | cw(30p) | cw(48p) . Multiplexer and demultiplexer Failure of power supply Yes Yes Yes (if practicable) Yes (if practicable) _ .T& lw(36p) | lw(54p) | cw(30p) | cw(30p) | cw(30p) | cw(48p) , ^ | l | c | c | c | c ^ | l | c | c | l | c ^ | c | l | l | l | l. Demultiplexer only Loss of incoming signal Yes Yes Yes Yes Loss of multiframe alignment Yes Yes Yes Yes { Alarm indication received from the remote signalling multiplex equipment } Yes Yes { Receipt of the service alarm indication from PCM mux } Yes Yes .Te .LP \fINote\fR \ \(em\ A \fIYes\fR | n the table signifies that an action should be taken as a consequence of the relevant fault condition. An \fIopen space\fR | in the table signifies that the relevant action should \fInot\fR be taken as a consequence of the relevant fault condition, if this condition is the only one present. If more than one fault condition is simultaneously present the relevant action should be taken if, for at least one of the conditions, a \fIYes\fR is defined in relation to this action. .nr PS 9 .RT .ad r \fBTable 2/G.732 [T2.732], p.\fR .sp 1P .RT .ad b .RT .sp 2P .LP \fB7\fR \fBJitter\fR .sp 1P .RT .sp 1P .LP 7.1 \fIJitter at 2048\ kbit/s output\fR .sp 9p .RT .PP In the case where the transmitting timing signal is derived from an internal oscillator, the peak\(hyto\(hypeak jitter at the 2048\ kbit/s output should not exceed 0.05\ UI when it is measured within the frequency range from \fIf\fR\d1\u\ =\ 20\ Hz to \fIf\fR\d4\u\ =\ 100\ kHz. .RT .sp 2P .LP 7.2 \fIJitter at 64\ kbit/s output (for interfaces according to\fR \fIRec. G.703)\fR .sp 1P .RT .PP 7.2.1 In the case where the incoming 2048 kbit/s signal has no jitter, the peak\(hyto\(hypeak jitter at the 64\ kbit/s output should not exceed 0.025\ UI when it is measured within the frequency range from\ \fIf\fR\d1\u\ =\ 20\ Hz to\ \fIf\fR\d4\u\ =\ 10\ kHz. The equivalent binary content of the test signal applied to the 2048\ kbit/s input shall be a pseudo\(hyrandom bit sequence of length\ 2\u1\d\u5\d\(em1 as specified in Recommendation\ O.151. .bp .sp 9p .RT .PP \fINote\fR \ \(em\ In order to carry out this measurement without invoking AIS at the 64\ kbit/s output, it will normally be necessary to include a frame alignment signal in the test signal. .PP 7.2.2 The jitter transfer function between the 2048\ kbit/s input and the 64\ kbit/s output should not exceed \(em29.6\ dB when measured over the frequency range\ \fIf\fR\d0\uto 10\ kHz. The frequency\ \fIf\fR\d0\ushould be less than 20\ Hz and as low as possible (e.g.\ 10\ Hz), taking into account the limitations of measuring equipment. .sp 9p .RT .PP \fINote\ 1\fR \ \(em\ The 2048 kbit/s test signal shall be modulated by sinusoidal jitter. The equivalent binary content of the test signal shall be\ 1000. .PP \fINote\ 2\fR \ \(em\ In order to carry out this measurement without invoking AIS at the 64\ kbit/s output, it will normally be necessary to include a frame alignment signal in the test signal. .PP \fINote\ 3\fR \ \(em\ The jitter reduction of 1/32 due to demultiplexing is equivalent to \(em30.1\ dB. .RT .sp 2P .LP \fBRecommendation\ G.733\fR .RT .sp 2P .ce 1000 \fBCHARACTERISTICS\ OF\ \fR \fBPRIMARY\ PCM\ MULTIPLEX\ EQUIPMENT\fR .EF '% Fascicle\ III.4\ \(em\ Rec.\ G.733'' .OF '''Fascicle\ III.4\ \(em\ Rec.\ G.733 %' .ce 0 .sp 1P .ce 1000 \fBOPERATING\ AT\ 1544\ kbit/s\fR .ce 0 .sp 1P .ce 1000 \fI(Geneva, 1972; further amended)\fR .sp 9p .RT .ce 0 .sp 1P .LP \fB1\fR \fBGeneral characteristics\fR .sp 1P .RT .sp 1P .LP 1.1 \fIFundamental characteristics\fR .sp 9p .RT .PP The encoding law used is the \(*m\(hylaw as specified in Recommendation\ G.711. The sampling rate, load capacity and the code are also specified in that Recommendation. .PP The number of quantized values is 255. Two character signals are reserved for zero value (11111111 and\ 01111111). .PP In some networks the all\(hy0 character signal (00000000) is eliminated to avoid loss of timing information to the digital line, resulting in 254 quantized values. .RT .sp 1P .LP 1.2 \fIBit rate\fR .sp 9p .RT .PP The nominal bit rate is 1544\ kbit/s. The tolerance on this rate is \(+- | 0\ parts per million (ppm). .RT .sp 1P .LP 1.3 \fITiming signal\fR .sp 9p .RT .PP It should be possible to derive the transmitting timing signal of a PCM multiplex equipment from an internal source, from the incoming digital signal and also from an external source. .RT .sp 2P .LP \fB2\fR \fBFrame structure\fR .sp 1P .RT .PP Refer to \(sc\(sc 3.1.1 and 3.1.2 of Recommendation G.704 for frame structure and use of derived channel time slots. .RT .sp 2P .LP \fB3\fR \fBLoss and recovery of frame alignment\fR .sp 1P .RT .PP The strategy for the loss and recovery of frame alignment should be according to Recommenda tion\ G.706, \(sc\ 2.1. .RT .sp 2P .LP \fB4\fR \fBFault conditions\fR \fBand consequent actions\fR .sp 1P .RT .sp 1P .LP 4.1 \fIFault conditions\fR .sp 9p .RT .PP The PCM multiplex equipment should detect the following conditions: .RT .PP 4.1.1 Failure of power supply. .PP 4.1.2 Loss of incoming signals at 1544\ kbit/s. .PP 4.1.3 Loss of frame alignment. .PP 4.1.4 Alarm indication received from the remote PCM multiplex equipment. .bp .sp 1P .LP 4.2 \fIConsequent actions\fR .sp 9p .RT .PP Further to the detection of a fault condition, appropriate actions should be taken as specified in Table\ 1/G.733. The consequent actions are as follows: .RT .PP 4.2.1 A service alarm indication should be generated to signify that the service provided by the PCM multiplex is no longer available. This indication should be forwarded to the switching and/or signalling equipment depending upon the arrangement provided. .sp 9p .RT .PP 4.2.2 The service alarm described in \(sc\ 4.2.1 above should be used to automatically remove the associated circuits from service and to restore them to service when frame alignment has been recovered. .sp 9p .RT .PP \fINote\fR \ \(em\ The removal of the associated circuits described in \(sc\ 4.2.2 above should be done in such a way that the circuits are not needlessly removed in the case of a brief isolated loss of frame alignment but are removed in the case of a permanent or intermittent loss of frame alignment. .PP It is also important to minimize the impact of signalling errors which may occur during periods of loss of frame alignment. These functions should be provided in the PCM multiplex equipment or in the switching/signalling equipment. .RT .PP 4.2.3 A prompt maintenance alarm indication should be generated to signify that performance is below acceptable standards and maintenance attention is required locally. .sp 9p .RT .PP 4.2.4 An alarm indication to the remote end should be generated by either forcing bit 2 in every channel time slot to the value\ 0 or by modifying the \fIS\fR \(hybit as described in \(sc\ 3.1.3.2.2 of Recommendation\ G.704 for the 12\ frame multiframe or by sending a frame alignment alarm sequence (1111111100000000) as described in \(sc\ 3.1.1.3\ (A)\(hy(3) of Recommendation\ G.704 for the 24\(hyframe multiframe. .sp 9p .RT .PP 4.2.5 Transmission should be suppressed at the analogue outputs. .sp 9p .RT .sp 1P .LP 4.2.6 \fIRapid indication of loss of frame alignment\fR .sp 9p .RT .PP An indication should be given to the Signalling System No.\ 6 equipment (digital version) when the PCM multiplex equipment (local end only) detects a loss of frame alignment. The average time to detect and give an indication of random bits in the frame alignment signal bit positions should not be greater than 3\ ms. This indication will serve the same function as that provided by the data carrier failure alarm in the analogue version (see Recommendation\ Q.275\ [1]). .RT .sp 2P .LP \fB5\fR \fBSignalling\fR .sp 1P .RT .sp 1P .LP 5.1 \fISignalling arrangement\fR .sp 9p .RT .PP Refer to \(sc 3.1.3 of Recommendation G.704. .RT .sp 1P .LP 5.2 \fILoss of multiframe alignment in case of\fR \fIchannel associated\fR \fIsignalling\fR \fIon 12 frame multiframe\fR .sp 9p .RT .PP \fI\fR Loss of multiframe alignment is assumed to have taken place when loss of frame alignment occurs. .RT .sp 1P .LP 5.3 \fIMinimization of\fR \fIquantizing distortion\fR \fIin case of\fR \fIchannel associated signalling\fR .sp 9p .RT .PP In the signalling frame only seven bits are available for encoding of voice frequencies. In order to minimize the quantizing distortion, the decoder output values are shifted slightly. All even numbered decoder output values \fIy\fR\d\fIn\fR\u, are changed to be equal to the next higher decision value, i.e.\ \fIx\fR \s6\fIn\fR +1 .PS 10 . All odd numbered decoder output values \fIy\fR \s6\fIn\fR +1 .PS 10 are changed to be equal to the same numbered decision value, i.e.\ \fIx\fR \s6\fIn\fR +1 .PS 10 , as shown on Figure\ 1/G.733. .RT .PP When suppression of the all\ 0 character signal is required, the value of the seventh bit is forced to be\ 1 when all the other bits of the character signal have the value\ 0. .bp .RT .ce \fBH.T. [T1.733]\fR .ce TABLE\ 1/G.733 .ce \fBFault conditions and consequent actions for the PCM\fR .ce \fBmultiplex equipment\fR .ps 9 .vs 11 .nr VS 11 .nr PS 9 .TS center box; cw(42p) | cw(48p) | cw(39p) sw(33p) sw(33p) sw(33p) , ^ | ^ | c | c | c | c. Equipment part Fault conditions Consequent actions { Service alarm indication generated } { Prompt maintenance alarm indication } { Alarm indication to the remote end generated } { Transmission suppressed at the analogue outputs } _ .T& lw(42p) | lw(48p) | cw(39p) | cw(33p) | cw(33p) | cw(33p) . Multiplexer and demultiplexer Failure of power supply Yes Yes Yes (if practicable) Optional _ .T& lw(42p) | lw(48p) | cw(39p) | cw(33p) | cw(33p) | cw(33p) , ^ | l | c | c | c | c ^ | l | c | c | c | l. Demultiplexer only { Loss of incoming signals at 1544 kbit/s } Yes Yes Yes Yes Loss of frame alignment Yes Yes Yes Yes { Alarme indication received from the remote end } Optional Yes Optional .TE .LP \fINote\ 1\fR \ \(em\ A \fIYes\fR | in the table signifies that an action should be taken as a consequence of the relevant fault condition. An \fIopen space\fR | in the table signifies that the relevant action should \fInot\fR | be taken as a consequence of the relevant fault condition, if this condition is the only one present. If more than one fault condition is simultaneously present the relevant action should be taken if, for at least one of the conditions, a \fIYes\fR is defined in relation to this action. .LP \fINote\ 2\fR \ \(em\ Indications of additional fault conditions, such as codec failure and excessive bit errors, are left to the discretion of individual Administrations. .nr PS 9 .RT .ad r \fBTableau 1/G.733 [T1.733], p. 3\fR .sp 1P .RT .ad b .RT .LP .rs .sp 21P .ad r \fBFigure 1/G.733, p. 4\fR .sp 1P .RT .ad b .RT .LP .bp .sp 2P .LP \fB6\fR \fBInterfaces\fR .sp 1P .RT .PP Analogue:\ Refer to Recommendations\ G.712, G.713 and G.714. .PP Digital: Refer to Recommendation\ G.703. .RT .sp 2P .LP \fBReference\fR .sp 1P .RT .LP [1] CCITT Recommendation \fIData channel failure detection\fR , Vol.\ VI, Rec.\ Q.275. \v'1P' .sp 2P .LP \fBRecommendation\ G.734\fR .RT .sp 2P .ce 1000 \fBCHARACTERISTICS\ OF\ \fR \fBSYNCHRONOUS\ DIGITAL\ MULTIPLEX\fR .EF '% Fascicle\ III.4\ \(em\ Rec.\ G.734'' .OF '''Fascicle\ III.4\ \(em\ Rec.\ G.734 %' .ce 0 .sp 1P .ce 1000 \fBEQUIPMENT\ OPERATING\ AT\ 1544\ kbit/s\fR .ce 0 .sp 1P .ce 1000 \fI(former Recommendation G.736 of Volume III of the Yellow Book)\fR .sp 9p .RT .ce 0 .sp 1P .LP \fB1\fR \fBGeneral characteristics\fR .sp 1P .RT .PP This Recommendation defines the characteristics of a synchronous multiplex equipment currently used for applications in dedicated data networks, to combine up to 23\ tributary channels at 64\ kbit/s in a 1544\ kbit/s digital stream. .PP \fINote\fR \ \(em\ For applications within an ISDN, it is expected that a 24\(hychannel multiplex will be used that has a frame structure conforming to Recommendation\ G.733. .RT .sp 1P .LP 1.1 \fIBit rate\fR .sp 9p .RT .PP The nominal bit rate is 1544 kbit/s. .PP \fINote\fR \ \(em\ The tolerance on this rate should be studied and specified. .RT .sp 1P .LP 1.2 \fITiming signals\fR .sp 9p .RT .PP It should be possible to derive the multiplexer timing signals from the composite clock signal of a centralized clock source as specified in Recommendation\ G.703, and from the 1544\ kbit/s incoming digital stream. .PP \fINote\fR \ \(em\ The desirability of also providing a 1544\ kHz transmitting timing signal from a centralized clock source should be further studied. .RT .sp 2P .LP \fB2\fR \fBFrame structure\fR .sp 1P .RT .sp 1P .LP 2.1 \fINumber of bits per channel time slot\fR .sp 9p .RT .PP There are eight bits per channel time slot, numbered from one to eight. .RT .sp 1P .LP 2.2 \fINumber of channel time slots per frame\fR .sp 9p .RT .PP There are 24 time slots per frame, numbered from 1 to 24. Successive bits for bytes\ 1 to\ 24 should be consecutively numbered from 2 to\ 193. The first bit should be reserved for optional use. The frame repetition rate is 8000\ Hz. .RT .sp 1P .LP 2.3 \fIChannel time slot assignment\fR \v'3p' .sp 9p .RT .PP 2.3.1 Channel time slots 1 to 23 are assigned to tributaries. .PP 2.3.2 Channel time slot 24 is assigned to frame alignment and service digits. Two alternative methods, as given in Tables\ 1/G.734 and\ 2/G.734 for allocation of these signals and associated frame alignment strategy are recommended. .bp .ce \fBH.T. [T1.734]\fR .ce TABLE\ 1/G.734 .ce \fBAllocation of time slot 24, Method 1\fR .ps 9 .vs 11 .nr VS 11 .nr PS 9 .TS center box; cw(228p) . Bit number of time slot 24 .TE .TS center box ; cw(33p) | cw(27p) | cw(27p) | cw(27p) | cw(33p) | cw(27p) | cw(27p) | cw(27p) . 1 2 3 4 5 6 7 8 _ Service digits Frame alignment signal .T& cw(33p) | cw(27p) | cw(27p) | cw(27p) | cw(33p) | lw(27p) | lw(27p) | cw(27p) . 1 0 1 1 1 0 .TE .LP \fINote\fR \ \(em\ Loss of frame alignment should be assumed to have taken place when more than three of twelve successive frames have an error in the frame alignment signal and/or in bit 1 of the 193\(hybit frame. Frame alignement should be assumed to have been recovered when four consecutive correct frame alignment signals have been received. .nr PS 9 .RT .ad r \fBTable 1/G.734 [T1.734], p.\fR .sp 1P .RT .ad b .RT .ce \fBH.T. [T2.734]\fR .ce TABLE\ 2/G.734 .ce \fBAllocation of time slot 24, Method 2\fR .ps 9 .vs 11 .nr VS 11 .nr PS 9 .TS center box; cw(60p) | cw(24p) sw(18p) sw(24p) sw(18p) sw(24p) sw(18p) sw(24p) sw(18p) , ^ | c | c | c | c | c | c | c | c. Frame number Bit number of time slot 24 1 2 3 4 5 6 7 8 _ .T& cw(60p) | cw(66p) | cw(102p) . 1 Service digits Frame alignment signal .T& cw(60p) | cw(66p) | cw(18p) | cw(24p) | cw(18p) | lw(24p) | lw(18p) . 0 0 1 0 1 _ .T& cw(60p) | cw(66p) | cw(18p) | cw(24p) | cw(18p) | cw(24p) | lw(18p) . 2 1 1 0 1 0 .TE .LP \fINote\fR \ \(em\ Loss of frame alignment should be assumed to have taken place when seven consecutive pairs of the frame alignment signal (00101, 11010) have been incorrectly received in their predicted positions. Frame alignment should be assumed to have been recovered when two consecutive correct pairs of frame alignment signals have been received. .nr PS 9 .RT .ad r \fBTable 2/G.734 [T2.734], p.\fR .sp 1P .RT .ad b .RT .sp 1P .LP .sp 1 2.4 \fIService digits\fR .sp 9p .RT .PP The use of service digits in channel time slot 24 is under study. .PP \fINote\fR \ \(em\ The first bit could be considered for framing algorithms. .bp .RT .sp 2P .LP \fB3\fR \fBFault conditions\fR \fBand consequent action\fR .sp 1P .RT .sp 1P .LP 3.1 \fIFault conditions\fR .sp 9p .RT .PP The digital multiplex equipment should detect the following fault conditions: .RT .LP \(em failure of power supply, .LP \(em loss of the incoming signal at 1544\ kbit/s, .LP \(em loss of frame alignment, .LP \(em loss of timing signals supplied from the centralized clock, .LP \(em alarm indication received from the remote digital multiplex equipment. .PP Some of the above fault conditions may optionally be detected by auxiliary equipment normally used in association with the digital multiplex equipment. .sp 1P .LP 3.2 \fIConsequent actions\fR .sp 9p .RT .PP Further to the detection of a fault condition, appropriate actions should be taken as specified in Table\ 3/G.734. .RT .ce \fBH.T. [T3.734]\fR .ce TABLE\ 3/G.734 .ce \fBFault conditions and consequent actions for the .ce digital multiplex equipment\fR .ps 9 .vs 11 .nr VS 11 .nr PS 9 .TS center box; cw(48p) | cw(54p) | cw(42p) sw(42p) sw(42p) , ^ | ^ | c | c | c. Equipment part Fault conditions { Consequent action (see Notes 1 and 2) } { Prompt maintenance alarm indication generated } { Alarm indication to the remote end transmitted (see Note 3) } { Multiplex out\(hyof\(hysync signal applied to 64 kbit/s output (see Note 4) } _ .T& cw(48p) | cw(54p) | cw(42p) | cw(42p) | cw(42p) . Multiplexer and demultiplexer Failure of power supply Yes Yes (if practicable) Yes (if practicable) _ .T& cw(48p) | lw(54p) | cw(42p) | cw(42p) | cw(42p) , ^ | l | c | c | c ^ | l | c | l | l. Demultiplexer only { Loss of incoming signal at 1544 kbit/s } Yes Yes Yes Loss of frame alignment Yes Yes Yes { Alarm indication receive from the remote end } Yes .TE .LP \fINote\ 1\fR \ \(em\ A \fIYes\fR | n the table signifies that an action should be taken as a consequence of the relevant fault condition. An \fIopen space\fR in the table signifies that the relevant action should \fInot\fR be taken as a consequence of the relevant fault condition, if this condition is the only one present. If more than one fault condition is simultaneously present, the relevant action should be taken if, for at least one of the conditions, a \fIYes\fR is defined in relation to this action. .LP \fINote\ 2\fR \ \(em\ These consequent actions may optionally be taken by auxiliary equipment normally used in conjunction with the digital multiplex equipment. .LP \fINote\ 3\fR \ \(em\ The alarm indication to the remote end may be generated by changing a service bit of time slot 24 from the state 1 to the state 0, if possible. .LP \fINote\ 4\fR \ \(em\ The binary content of the multiplex out\(hyof\(hysync signal is under study. One Administration uses 00011010. .nr PS 9 .RT .ad r \fBTable 3/G.734 [T3.734], p.\fR .sp 1P .RT .ad b .RT .LP .bp .sp 2P .LP \fB4\fR \fBMultiplexing method\fR .sp 1P .RT .PP Cyclic byte interleaving in the tributary numbering order should be used. The digital multiplex equipment should translate any incoming byte that contains only 0s into the zero byte suppression code. .PP \fINote\ 1\fR \ \(em\ The content of the zero byte suppression code is under study. .PP \fINote\ 2\fR \ \(em\ Further study is needed for the case when the zero suppression code must be extracted. .RT .sp 2P .LP \fB5\fR \fBInput\fR \fBjitter\fR \fBand\fR \fBwander\fR .sp 1P .RT .PP The amount of jitter and wander that should be tolerated at the input of the demultiplexer should be according to Recommendation\ G.824, \(sc\ 3.1.1. .RT .sp 2P .LP \fB6\fR \fBDigital interface\fR .sp 1P .RT .PP The digital interface at 64\ kbit/s and 1544\ kbit/s should be in accordance with Recommendation\ G.703. \v'2P' .RT .sp 2P .LP \fBRecommendation\ G.735\fR .RT .sp 2P .ce 1000 \fBCHARACTERISTICS\ OF\ \fR \fBPRIMARY\ PCM\ MULTIPLEX\ EQUIPMENT\fR .EF '% Fascicle\ III.4\ \(em\ Rec.\ G.735'' .OF '''Fascicle\ III.4\ \(em\ Rec.\ G.735 %' .ce 0 .ce 1000 \fBOPERATING\ AT\ 2048\ kbit/s\ AND\ OFFERING\fR .ce 0 .sp 1P .ce 1000 \fBSYNCHRONOUS\ DIGITAL\ ACCESS\ AT\ 384\ kbit/s\ AND/OR\ 64\ kbit/s\fR .ce 0 .sp 1P .ce 1000 \fI(former Recommendation G.737 of Volume III of the Yellow Book)\fR .sp 9p .RT .ce 0 .sp 1P .PP This Recommendation gives the characteristics of a PCM multiplex equipment operating at 2048\ kbit/s and providing one or several of the following internal digital access options: .sp 1P .RT .LP \(em bidirectional synchronous 64\ kbit/s channels (see Figure\ 1a/G.735); .LP \(em unidirectional synchronous 384\ kbit/s channels (see Figure\ 1b/G.735). .PP The 384 kbit/s channel is based on the allocation of 6\ \(mu\ 64\ kbit/s time slots, e.g. for setting up sound\(hyprogramme circuits according to Recommendations\ J.41 and J.42. .PP Because these circuits are specified as unidirectional, the equipment for insertion/extraction has to be separated as shown in Figure\ 1b/G.735. .RT .sp 2P .LP \fB1\fR \fBGeneral characteristics\fR .sp 1P .RT .sp 1P .LP 1.1 \fIFundamental characteristics for voice channel encoding\fR .sp 9p .RT .PP The encoding law used is the A\(hylaw as specified in Recommendation\ G.711. The sampling rate, load capacity and the code are also specified in that Recommendation. .PP The number of quantized values is 256. .PP \fINote\fR \ \(em\ The inversion of bits 2, 4, 6 and 8 is covered by the encoding law and is applicable only to voice channel time slots. .RT .sp 1P .LP 1.2 \fIBit rate\fR .sp 9p .RT .PP The nominal bit rate is 2048\ kbit/s. The tolerance on this rate is \(+- | 0\ parts per million (ppm). .bp .RT .sp 1P .LP 1.3 \fITiming signal\fR .sp 9p .RT .PP It should be possible to derive the transmit timing signal from any of the following: .RT .LP a) from the received 2048\ kbit/s signal, .LP b) from an external source at 2048\ kHz (see \(sc\ 5), .LP c) from an internal oscillator. .PP \fINote\fR \ \(em\ The provision of a timing signal output, available for the purpose of synchronizing other equipments, is an option that might be required depending upon national synchronization arrangements. .sp 1P .LP 1.4 \fITypes of access:\fR \v'3p' .sp 9p .RT .LP a) access for bidirectional synchronous 64\ kbit/s channels (see Figure 1a/G.735); .LP b) access for unidirectional synchronous 384\ kbit/s channels (see Figure 1b/G.735). .PP \fINote\fR \ \(em\ The synchronous insertion of a digital sound programme signal into a 384\ kbit/s channel requires the internal regeneration of a timing signal\ T synchronized by the 2048\ kbit/s signal\ I\d1\u. The timing signal is used for synchronizing the sampling frequency of the analogue/digital converters producing the digital sound programme signal. .LP .rs .sp 35P .ad r \fBFigure 1/G.735, p.\fR .sp 1P .RT .ad b .RT .LP .bp .sp 2P .LP \fB2\fR \fBFrame structure\fR \fBand use of\fR \fBderived channel time slots\fR .sp 1P .RT .sp 1P .LP 2.1 \fIFrame structure of 2048 kbit/s signal\fR .sp 9p .RT .PP Refer to \(sc\ 2.3 of Recommendation G.704. Bit 1 of the frame should be used in accordance with \(sc\ 2.3.3 of Recommendation\ G.704, i.e.\ for a CRC check bit procedure. .RT .sp 2P .LP 2.2 \fIUse of derived channel time slots\fR .sp 1P .RT .sp 1P .LP 2.2.1 \fITelephone channels\fR .sp 9p .RT .PP It should be possible to assign channel time slots\ 1 to\ 15 and 17\ to\ 31 to thirty telephone channels numbered from 1\ to\ 30. .RT .sp 1P .LP 2.2.2 \fI64 kbit/s access\fR .sp 9p .RT .PP The number of accessible channel time slots should be at least four and the equipment shall allow access to any of channel time slots 1\ to\ 15 and 17\ to\ 31. .PP \fINote\fR \ \(em\ Equipment exists which provides access to at least four channel time slots in the following order of priority: 6 \(em 22 \(em 14 \(em 30 \(em 2 \(em 18 \(em 10 \(em 26 \(em 4 \(em 20 \(em 12 \(em 28 \(em 8 \(em 24 \(em 5 \(em 21 \(em 13 \(em 29\ \(em 1 \(em 17 \(em 9 \(em 25 \(em 3 \(em 19 \(em 11 \(em 27 \(em 7 \(em 23 \(em 15 \(em\ 31. .RT .sp 1P .LP 2.2.3 \fI384 kbit/s access\fR .sp 9p .RT .PP The time slot allocation for digital channels with a bit rate at 384\ kbit/s is given in Table\ 1/G.735. .RT .ce \fBH.T. [T1.735]\fR .ce TABLE\ 1/G.735 .ps 9 .vs 11 .nr VS 11 .nr PS 9 .TS center box; cw(36p) sw(30p) sw(36p) sw(30p) sw(36p) | cw(60p) , c | c | c | c | c | ^ . 384 kbit/s channels (Note 1) { Digital sound\(hyprogramme access points } A B C D E _ .T& cw(36p) | cw(30p) | cw(36p) | cw(30p) | cw(36p) | cw(60p) . 1\(hy2\(hy3 4\(hy5\(hy6 7\(hy8\(hy9 10\(hy11\(hy12 13\(hy14\(hy15 I3, T, E3 .T& cw(36p) | cw(30p) | cw(36p) | cw(30p) | cw(36p) | cw(60p) . 17\(hy18\(hy19 20\(hy21\(hy22 23\(hy24\(hy25 26\(hy27\(hy28 29\(hy30\(hy31 Figure 1b/G.735 .TE .LP \fINote\ 1\fR \ \(em\ The five possible 384 kbit/s channels in a 2048 kbit/s stream are numbered A to E. Preferably the channel pairs A\(hyB and C\(hyD should be used for stereophonic transmission. .LP \fINote\ 2\fR \ \(em\ If the channel time slot 16 which is assigned to signalling as covered in \(sc\ 5 is not needed for signalling, it may be used for purposes other than a voice channel encoded within the PCM multiplex equipment. .nr PS 9 .RT .ad r \fBTable 1/G.735 [T1.735], p.\fR .sp 1P .RT .ad b .RT .sp 2P .LP \fB3\fR \fBFrame alignment and CRC procedures\fR .sp 1P .RT .PP An illustration of the procedure is given in Figure\ 2/G.706. .RT .sp 1P .LP 3.1 \fILoss of frame alignment\fR .sp 9p .RT .PP Refer to \(sc\ 4.1.1 of Recommendation G.706. .RT .sp 1P .LP 3.2 \fIRecovery of frame alignment\fR .sp 9p .RT .PP Refer to \(sc\ 4.1.2 of Recommendation G.706. .RT .sp 1P .LP 3.3 \fICRC multiframe alignment in TSO\fR .sp 9p .RT .PP Refer to \(sc 4.2 of Recommendation G.706. .RT .sp 1P .LP 3.4 \fICRC bit monitoring\fR .sp 9p .RT .PP Refer to \(sc 4.3 of Recommendation G.706. .bp .RT .sp 2P .LP \fB4\fR \fBFault conditions\fR \fBand consequent actions\fR .sp 1P .RT .sp 1P .LP 4.1 \fIFault conditions\fR .sp 9p .RT .PP The PCM multiplex equipment should detect the following fault conditions: .RT .PP 4.1.1 Failure of power supply. .sp 9p .RT .PP 4.1.2 Failure of codec (except when using single channel codecs). .sp 9p .RT .PP As a minimum requirement, this fault condition should be recognized when for at least one signal level in the range \(em21 to \(em6\ dBm0, the signal\(hyto\(hyquantizing noise ratio performance of the local codec is 18\ dB or more below the level recommended in Recommendation\ G.712. .PP 4.1.3 Loss of incoming signals at the 64\ kbit/s and 384\ kbit/s tributary input ports. .sp 9p .RT .PP \fINote\ 1\fR \ \(em\ This detection is not mandatory when contradirectional interfaces are used. .PP \fINote\ 2\fR \ \(em\ The detection of this fault condition is not mandatory for channel time slot\ 16 when channel associated signalling is used and the signalling multiplex equipment is situated within a few metres of the PCM multiplex equipment. .RT .PP 4.1.4 Loss of the incoming signal at 2048\ kbit/s. .sp 9p .RT .PP \fINote\ 1\fR \ \(em\ The detection of this fault condition is required only when it does not result in an indication of loss of frame alignment. .PP \fINote\ 2\fR \ \(em\ Where separate circuits are used for the digital signal and the timing signal, the loss of either or both should constitute loss of the incoming signal. .RT .PP 4.1.5 Loss of frame alignment. .sp 9p .RT .PP 4.1.6 Excessive bit error ratio detected by monitoring the frame alignment signal. .sp 9p .RT .PP 4.1.6.1 With a random bit error ratio of \(= | 0\uD\dlF261\u4\d, the probability of activating the indication of fault condition within a few seconds should be less than\ 10\uD\dlF261\u6\d. .sp 9p .RT .PP With a random bit error ratio of \(>=" | 0\uD\dlF261\u3\d, the probability of activating the indication of fault condition within a few seconds should be higher than\ 0.95. .PP 4.1.6.2 With a random bit error ratio of \(>=" | 0\uD\dlF261\u3\d, the probability of deactivating the indication of fault condition within a few seconds should be almost\ 0. .sp 9p .RT .PP With a random bit error ratio of \(= | 0\uD\dlF261\u4\d, the probability of deactivating the indication of fault condition within a few seconds should be higher than\ 0.95. .PP \fINote\fR \ \(em\ The activating and the deactivating period specified as \*Qa few seconds\*U is intended to be in the order of 4\ to 5\ seconds. .RT .PP 4.1.7 Alarm indication received from the remote PCM multiplex equipment (see \(sc\ 4.2.3). .sp 9p .RT .sp 1P .LP 4.2 \fIConsequent actions\fR .sp 9p .RT .PP Further to the detection of a fault condition, appropriate actions should be taken as specified in Table\ 2/G.735. The consequent actions are as follows: .RT .PP 4.2.1 Service alarm indication generated to signify that the service provided by the PCM multiplex is no longer available. This indication should be forwarded at least to the switching and/or signalling multiplex equipment depending upon the arrangements provided. The indication should be given as soon as possible and not later than 2\ ms after detection of the relevant fault condition. .sp 9p .RT .PP This specification, taking into account the specification given in \(sc\ 4.2.5, is equivalent to recommending that the average time to detect a loss of frame alignment or a loss of the incoming 2048\ kbit/s signal and to give the relevant indication should not be greater than 3\ ms. .PP When using common channel signalling the indication should be forwarded to the switching equipment by means of a separate interface on the PCM multiplex equipment. .bp .RT .PP 4.2.2 Prompt maintenance alarm indication generated to signify that performance is below acceptable standards and maintenance attention is required locally. When the AIS (see General Notes below to \(sc\ 4.2) at 2048\ kbit/s input is detected, the prompt maintenance alarm indication associated with loss of frame alignment (see \(sc\ 4.1.5) and excessive error ratio (see \(sc\ 4.1.6) should be inhibited, while the rest of the consequent actions are in accordance with those associated in Table\ 2/G.735 with the two fault conditions. .sp 9p .RT .PP \fINote\fR \ \(em\ The location and provision of any visual and/or audible alarm activated by the alarm indications given in \(sc\(sc\ 4.2.1 and\ 4.2.2, is left to the discretion of each Administration. .PP 4.2.3 Alarm indication to the remote end transmitted by changing bit\ 3 of channel time slot\ 0 from the state\ 0 to the state\ 1 in those frames not containing the frame alignment signal. This should be effected as soon as possible. .sp 9p .RT .PP 4.2.4 Transmission suppressed at the analogue voice\(hyfrequency outputs. .sp 9p .RT .PP 4.2.5 AIS applied to all 64\ kbit/s and 384\ kbit/s outputs (see General Notes below \(sc\ 4.2). For 64\ kbit/s outputs, this action should be taken as soon as possible and not later than two ms after the detection of the fault condition. .sp 9p .RT .PP 4.2.6 AIS applied to relevant time slots in the composite 2048\ kbit/s output signal (if suspension of incoming 64\ kbit/s and/or 384\ kbit/s signals is provided). .sp 9p .RT .sp 1P .LP \fIGeneral Notes to \(sc\ 4.2\fR .sp 9p .RT .PP \fINote\ 1\fR \ \(em\ The equivalent binary content of the alarm indication signal (AIS) is a continuous stream of binary 1s. The strategy for detecting the presence of the AIS should be such that with a high probability the AIS is detectable even in the presence of random errors having a mean error rate of\ 1 in 10\u3\d. Nevertheless, a signal in which all the binary elements, with the exception of the frame alignment signal, are in the state\ 1, should not be taken as an AIS. .PP \fINote\ 2\fR \ \(em\ All timing requirements quoted apply equally to restoration, subsequent to the fault condition clearing. .RT .sp 2P .LP \fB5\fR \fBSignalling\fR .sp 1P .RT .PP Text as in Recommendation G.732. .RT .sp 2P .LP \fB6\fR \fBInterfaces\fR .sp 1P .RT .sp 1P .LP 6.1 \fIAudio frequency interface\fR .sp 9p .RT .PP The analogue audio frequency interfaces should be in accordance with Recommendations\ G.712, G.713, G.714 and\ G.715. .RT .sp 1P .LP 6.2 \fIDigital interfaces\fR .sp 9p .RT .PP The digital interfaces at 2048\ kbit/s should be in accordance with Recommendation\ G.703. .PP The digital interfaces at 64\ kbit/s should be of either the codirectional or the contradirectional type specified in Recommendation\ G.703. The specifications for 64\ kbit/s interfaces are not mandatory for channel associated signalling. The interface for external synchronization of the transmitting timing signal should be in accordance with Recommendation\ G.703. .PP The need to define a digital interface operating at 384\ kbit/s is under study. .PP \fINote\ 1\fR \ \(em\ It should be noted that, according to the principle of minimizing the number of different types of interfaces, the information rate of 384\ kbit/s will be offered to customers at the user/network interface level using the 2048\ kbit/s interface as defined in Recommendations\ I.431 and G.703. .PP \fINote\ 2\fR \ \(em\ In the case of the 64 kbit/s codirectional interface, the design of the input ports should take account of the need to provide octet alignment, to allow controlled slips when the tributary timing and that of the multiplexer timing source are plesiochronous, and to absorb jitter and wander up to the limits given in Recommendation\ G.823. .bp .RT .LP .ce \fBH.T. [T2.735]\fR .ce TABLE\ 2/G.735 .ce \fBFault conditions and consequent actions for the .ce PCM multiplex equipment\fR .ps 9 .vs 11 .nr VS 11 .nr PS 9 .TS center box; cw(30p) | cw(36p) | cw(30p) sw(24p) sw(30p) sw(24p) sw(30p) sw(24p) , ^ | ^ | c | c | c | c | c | l. Equipment part { Fault conditions (see \(sc\ 4.1) } { Consequent actions (see \(sc\ 4.2) Service alarm indication generated } { Prompt maintenance alarm indication generated } { Alarm indication remote end transmitted } { Transmission suppressed at the analogue voice\(hyfrequency outputs } { AIS applied to all 64\ kbit/s and 384 kbit/s outputs } { AIS to the relevant time slot of the 2048\ kbit/s composite signal } _ .T& lw(30p) | lw(36p) | cw(30p) | cw(24p) | cw(30p) | cw(24p) | cw(30p) | cw(24p) , ^ | l | c | c | c | c | l | l. { Multiplexer and\ demulti plexer } Failure of power supply Yes Yes Yes (if practicable) Yes (if practicable) Yes (if practicable) Yes (if practicable) Failure of codec Yes Yes Yes Yes _ .T& lw(30p) | lw(36p) | cw(30p) | cw(24p) | lw(30p) | lw(24p) | lw(30p) | lw(24p) . Multiplexer only { Loss of incoming signal at 64\ kbit/s and/or 384 kbit/s inputs (see Note under \(sc\ 4.1.3) } Yes Yes _ .T& lw(30p) | lw(36p) | cw(30p) | cw(24p) | cw(30p) | cw(24p) | cw(30p) | lw(24p) , ^ | c | c | c | c | c | l | c ^ | c | c | c | c | l | c | l ^ | l | l | l | l | l | l | l. Demulti plexer only { Loss of incoming signal at 2048\ kbit/s } Yes Yes Yes Yes Yes { Loss of frame alignment (see Note 2 of Rec.\ G.706, \(sc\ 4.2) } Yes Yes (see\ \(sc\ 4.2.2) Yes Yes Yes { Error ratio 1 | (mu | 0\uD\dlF261\u3\d on the frame alignment signal } Yes Yes (see\ \(sc\ 4.2.2) Yes Yes Yes { Alarm indication received from the remote end } Yes .TE .LP \fINote\fR \ \(em\ A \fIYes\fR | in the table signifies that an action should be taken as a consequence of the relevant fault condition. An \fIopen space\fR | in the table signifies that the relevant action should \fInot\fR be taken as a consequence of the relevant fault condition, if this condition is the only one present. If more than one fault condition is simultaneously present, the relevant action should be taken if, for at least one of the conditions, a \fIYes\fR is defined in relation to this action. .nr PS 9 .RT .ad r \fBTable 1/G.735 + Note { 2.735], p.\fR .sp 1P .RT .ad b .RT .LP .bp .LP \fB7\fR \fBJitter\fR .sp 1P .RT .sp 2P .LP 7.1 \fIJitter at 2048\ kbit/s output\fR .sp 1P .RT .PP 7.1.1 In the case where the transmitting timing signal is derived from an internal oscillator, the peak\(hyto\(hypeak jitter at the 2048 kbit/s output should not exceed 0.05\ UI when it is measured within the frequency range from \fIf\fR\d1\u\ =\ 20\ Hz to \fIf\fR\d4\u\ =\ 100\ kHz. See Figure\ 2/G.823. .sp 9p .RT .PP 7.1.2 In the case where the transmitting timing signal is derived from an external source having no jitter, the peak\(hyto\(hypeak jitter at the 2048\ kbit/s output should not exceed 0.05\ UI when it is measured within the frequency range from \fIf\fR\d1\u\ =\ 20\ Hz to\ \fIf\fR\d4\u\ =\ 100\ kHz. .PP 7.1.3 In the case where the transmitting timing signal is derived from the incoming 2048 kbit/s signal having no jitter, the peak\(hyto\(hypeak jitter at the 2048\ kbit/s output should not exceed 0.10\ UI\ when it is measured within the frequency range from\ \fIf\fR\d1\u\ =\ 20\ Hz to\ \fIf\fR\d4\u\ =\ 100\ kHz. The equivalent binary content of the test signal applied at the 2048\ kbit/s input shall be a pseudo\(hyrandom bit sequence of length 2\u1\d\u5\d\(em1 as specified in Recommendation\ O.151. .PP \fI Note\fR \ \(em\ It may be necessary to include a frame alignment signal in the test signal to enable the measurement to be carried out. .sp 2P .LP 7.2 \fIJitter at tributary outputs\fR .sp 1P .RT .sp 1P .LP 7.2.1 \fIJitter at 64 kbit/s output\fR .sp 9p .RT .PP In the case where the incoming 2048 kbit/s signal has no jitter, the peak\(hyto\(hypeak jitter at the 64\ kbit/s output should not exceed 0.025\ UI when it is measured within the frequency range from \fIf\fR\d1\u\ =\ 20\ Hz to \fIf\fR\d4\u\ =\ 10\ kHz. The equivalent binary content of the test signal applied to the 2048\ kbit/s input shall be a pseudo\(hyrandom bit sequence of length\ 2\u1\d\u5\d \(em1 as specified in Recommendation\ O.151. .PP \fINote\fR \ \(em\ In order to carry out this measurement without invoking AIS at the 64\ kbit/s output, it will normally be necessary to include a frame alignment signal in the test signal. .RT .sp 1P .LP 7.2.2 \fIJitter at 384 kbit/s output\fR .sp 9p .RT .PP Since the physical and electrical characteristics of a 384 kbit/s interface are identical to those of the 2048\ kbit/s interface, the specification of this parameter is the same as that given in \(sc\ 7.1.3 above. .RT .sp 2P .LP 7.3 \fIJitter transfer functions\fR .sp 1P .RT .PP 7.3.1 The jitter transfer function between the 2048\ kHz external synchronisation signal and the 2048\ kbit/s output signal should not exceed the gain/frequency limits given in Figure\ 2/G.735. The 2048\ kHz signal shall be modulated with sinusoidal jitter. .sp 9p .RT .PP Some Administrations require that equipment be fitted with jitter reducers . In this case, the jitter transfer junction should not exceed the gain/frequency limits given in Figure\ 3/G.735. .PP 7.3.2 In the case where the transmitting timing is derived from the incoming signal, the jitter transfer junction between the 2048\ kbit/s input and 2048\ kbit/s output shall be as specified in \(sc\ 7.3.1. .sp 9p .RT .PP \fINote\ 1\fR \ \(em\ The 2048 kbit/s test signal shall be modulated by sinusoidal jitter. The equivalent binary content of the test signal shall be\ 1000. .PP \fINote\ 2\fR \ \(em\ It may be necessary to include a frame alignment signal in the test signal to enable the measurement to be carried out. .RT .PP 7.3.3 The jitter transfer function between the 2048\ kbit/s and the 64\ kbit/s output should not exceed \(em29.6\ dB when measured over the frequency range\ \fIf\fR\d0\uto 10\ kHz. The frequency\ \fIf\fR\d0\ushould be less than 20\ Hz and as low as possible (e.g.\ 10\ Hz), taking into account the limitations of measuring equipment. .sp 9p .RT .PP \fINote\ 1\fR \ \(em\ The 2048 kbit/s test signal shall be modulated by sinusoidal jitter. The equivalent binary content of the test signal shall be\ 1000. .PP \fINote\ 2\fR \ \(em\ In order to carry out this measurement without invoking AIS at the 64\ kbit/s output, it will normally be necessary to include a frame alignment signal in the test signal. .PP \fINote\ 3\fR \ \(em\ The jitter reduction of 1/32 due to demultiplexing is equivalent to \(em30.1\ dB. .bp .RT .PP 7.3.4 Since the physical and electrical characteristics of a 384\ kbit/s interface are identical to those of the 2048\ kbit/s interface, the jitter transfer function between the 2048\ kbit/s input and the 384\ kbit/s output is the same as that given in \(sc\(sc\ 7.3.1 and\ 7.3.2 above. .sp 9p .RT .LP .rs .sp 24P .ad r \fBFigure 2/G.735, p.\fR .sp 1P .RT .ad b .RT .LP .rs .sp 23P .ad r \fBFigure 3/G.735, p.\fR .sp 1P .RT .ad b .RT .LP .bp .sp 2P .LP \fBRecommendation\ G.736\fR .RT .sp 2P .ce 1000 \fBCHARACTERISTICS\ OF\ A\ \fR \fBSYNCHRONOUS\ DIGITAL\fR .EF '% Fascicle\ III.4\ \(em\ Rec.\ G.736'' .OF '''Fascicle\ III.4\ \(em\ Rec.\ G.736 %' .ce 0 .sp 1P .ce 1000 \fBMULTIPLEX\ EQUIPMENT\ OPERATING\ AT\ 2048\ kbit/s\fR .ce 0 .sp 1P .ce 1000 \fI(former Recommendation G.738 of Volume III of the Yellow Book)\fR .sp 9p .RT .ce 0 .sp 1P .PP This Recommendation gives the characteristics of a synchronous digital multiplex equipment, to combine up to 31\ tributary channels at 64\ kbit/s in a 2048\ kbit/s digital stream. It is foreseen that in the future the need may arise to devote\ \fIn\fR \ 64\ kbit/s time slots to services requiring more than a single 64\ kbit/s channel. The additions to this Recommendation to allow this facility (e.g.\ definition of proper interfaces at \fIn\fR \ \(mu\ 64\ kbit/s) are under study. .sp 1P .RT .sp 2P .LP \fB1\fR \fBGeneral characteristics\fR .sp 1P .RT .sp 1P .LP 1.1 \fIBit rate\fR .sp 9p .RT .PP The nominal bit rate is 2048\ kbit/s. The tolerance on this rate is \(+- | 0\ parts per million (ppm). .RT .sp 1P .LP 1.2 \fITiming signal\fR .sp 9p .RT .PP It should be possible to derive the transmit timing signal from any of the following: .RT .LP a) from the received 2048\ kbit/s signal, .LP b) from an external source at 2048\ kHz (see \(sc\ 5), .LP c) from an internal oscillator. .PP \fINote\ 1\fR \ \(em\ The possibility of also deriving the transmitting timing signal from a 64\ kbit/s tributary is under study. .PP \fINote\ 2\fR \ \(em\ The provision of a timing signal output, available for the purpose of synchronizing other equipments, is an option that might be required depending upon national synchronization arrangements. .RT .sp 2P .LP \fB2\fR \fBFrame structure\fR .sp 1P .RT .PP Refer to \(sc2.3 of Recommendation G.704 for frame structure and for use of derived channel time slots. Bit\ 1 of the frame should be used in accordance with \(sc\ 2.3.3 of Recommendation\ G.704, i.e.\ for a CRC check bit procedure. .PP \fINote\fR \ \(em\ In case of interconnection with multiplex equipment using time slot\ 16 for internal purposes, the use of this time slot for a 64\ kbit/s tributary could be excluded. .RT .sp 2P .LP \fB3\fR \fBFrame alignment and CRC procedures\fR .sp 1P .RT .PP An illustration of the procedure is given in Figure\ 2/G.706. .RT .sp 1P .LP 3.1 \fILoss of frame alignment\fR .sp 9p .RT .PP Refer to \(sc\ 4.1.1 of Recommendation\ G.706. .RT .sp 1P .LP 3.2 \fIRecovery of frame alignment\fR .sp 9p .RT .PP Refer to \(sc\ 4.1.2 of Recommendation\ G.706. .RT .sp 1P .LP 3.3 \fICRC multiframe alignment in TS0\fR .sp 9p .RT .PP Refer to \(sc\ 4.2 of Recommendation\ G.706. .RT .sp 1P .LP 3.4 \fICRC bit monitoring\fR .sp 9p .RT .PP Refer to \(sc\ 4.3 of Recommendation\ G.706. .bp .RT .sp 2P .LP \fB4\fR \fBFault conditions\fR \fBand consequent actions\fR .sp 1P .RT .sp 1P .LP 4.1 \fIFault conditions\fR .sp 9p .RT .PP The digital muldex should detect the following fault conditions: .RT .PP 4.1.1 Failure of power supply. .sp 9p .RT .PP 4.1.2 Loss of the incoming signal at the 64\ kbit/s tributary input port. .sp 9p .RT .PP \fINote\fR \ \(em\ This detection is not mandatory when contradirectional interfaces are used. .PP 4.1.3 Loss of the incoming signal at 2048 kbit/s. .sp 9p .RT .PP \fINote\ 1\fR \ \(em\ The detection of this fault condition is required only when it does not result in an indication of loss of frame alignment. .PP \fINote\ 2\fR \ \(em\ Where separate circuits are used for the digital signal and the timing signal, the loss of either or both should constitute loss of the incoming signal. .RT .PP 4.1.4 Loss of frame alignment at 2048 kbit/s. .sp 9p .RT .PP 4.1.5 Excessive bit error ratio detected by monitoring the frame alignment signal. .sp 9p .RT .PP 4.1.5.1 With a random bit error ratio of \(= | 0\uD\dlF261\u4\d, the probability of activating the indication of fault condition within a few seconds should be less than\ 10\uD\dlF261\u6\d. .sp 9p .RT .PP With a random bit error ratio of \(>=" | 0\uD\dlF261\u3\d, the probability of activating the indication of fault condition within a few seconds should be higher than\ 0.95. .PP 4.1.5.2 With a random bit error ratio of \(>=" | 0\uD\dlF261\u3\d, the probability of desactivating the indication of fault condition within a few seconds should be almost\ 0. .sp 9p .RT .PP With a random bit error ratio of \(= | 0\uD\dlF261\u4\d, the probability of of desactivating the indication of fault condition within a few seconds should be higher than\ 0.95. .PP \fINote\fR \ \(em\ The activating and the deactivating period specified as \*Qa few seconds\*U is intended to be in the order of 4 to 5\ seconds. .RT .PP 4.1.6 Alarm indication received from the remote digital muldex (see \(sc\ 4.2). .sp 9p .RT .sp 1P .LP 4.2 \fIConsequent actions\fR .sp 9p .RT .PP Further to the detection of a fault condition, appropriate actions should be taken as specified in Table\ 1/G.736. The consequent actions are as follows: .RT .PP 4.2.1 Prompt maintenance alarm indication generated to signify that performance is below acceptable standards and maintenance attention is required locally. When the AIS (see General Notes below to \(sc\ 4.2) at 2048\ kbit/s input is detected, the prompt maintenance alarm indication associated with loss of frame alignment (see \(sc\ 4.1.4) and excessive error ratio (see \(sc\ 4.1.5) should be inhibited, while the rest of the consequent actions are in accordance with those associated in Table\ 1/G.736 with the two fault conditions. .sp 9p .RT .PP \fINote\fR \ \(em\ The location and provision of any visual and/or audible alarm activated by the alarm indications given in \(sc\ 4.2.1 is left to the discretion of each Administration. .PP 4.2.2 Alarm indication to the remote end transmitted by changing bit\ 3 of channel time slot\ 0 from the state\ 0 to the state\ 1 in those frames not containing the frame alignment signal. This should be effected as soon as possible. .bp .sp 9p .RT .PP 4.2.3 AIS applied to all 64\ kbit/s outputs (see General Notes below to \(sc\ 4.2). This action should be taken as soon as possible and not later than 2\ ms after the detection of the fault condition. .sp 9p .RT .PP 4.2.4 AIS applied to relevant time slots in the composite 2048\ kbit/s output signal (if supervision of incoming 64\ kbit/s signal is provided). .sp 9p .RT .sp 1P .LP \fIGeneral Notes to \(sc\ 4.2\fR .sp 9p .RT .PP \fINote\ 1\fR \ \(em\ The equivalent binary content of the alarm indication signal (AIS) is a continuous stream of binary\ 1s. The strategy for detecting the presence of the AIS should be such that with a high probability the AIS is detectable even in the presence of random errors having a mean error ratio\ 1 | (mu | 0\uD\dlF261\u3\d. Nevertheless, a signal in which all the binary elements, with the exception of the frame alignment signal, are in the state\ 1, should not be taken as an AIS. .PP \fINote\ 2\fR \ \(em\ All timing requirements quoted apply equally to restoration, subsequent to the fault condition clearing. .RT .ce \fBH.T. [T1.736]\fR .ce TABLE\ 1/G.736 .ce \fBFault conditions and consequent actions for the 2048 kbit/s\fR .ce .ce \fBsynchronous digital multiplex equipment\fR .ps 9 .vs 11 .nr VS 11 .nr PS 9 .TS center box; cw(36p) | cw(54p) | cw(30p) sw(30p) sw(30p) sw(48p) , ^ | ^ | c | c | c | c. Equipment part { Fault conditions (see \(sc\ 4.1) } { Consequent actions (see \(sc\ 4.2) } { Prompt maintenance alarm indication generated } { Alarm indication to the remote end transmitted } { AIS applied to all 64\ kbit/s outputs } { AIS applied to the relevant time slot of the 2048 kbit/s composite signal } _ .T& lw(36p) | lw(54p) | cw(30p) | cw(30p) | cw(30p) | cw(48p) . Multiplexer and demultiplexer Failure of power supply Yes Yes (if practicable) Yes (if practicable) Yes (if practicable) _ .T& lw(36p) | lw(54p) | cw(30p) | cw(30p) | cw(30p) | cw(48p) . Multiplexer only { Loss of incoming signal at a 64 kbit/s input (see Note under \(sc\ 4.1.2) } Yes Yes _ .T& lw(36p) | lw(54p) | cw(30p) | cw(30p) | cw(30p) | lw(48p) , ^ | c | c | c | l | c ^ | c | c | l | l | l ^ | l | l | l | l | l. Demultiplexer only { Loss of incoming signal at\ 2048\ kbit/s } Yes Yes Yes { Loss of frame alignment (see Note 2 of Rec. G.706, \(sc\ 4.2) } Yes (see \(sc\ 4.2.1) Yes Yes { Error ratio 1 | (mu | 0\uD\dlF261\u3\d on the frame alignment signal } Yes (see \(sc\ 4.2.1) Yes Yes { Alarm indication received from the remote end } .TE .LP \fINote\fR \ \(em\ A \fIYes\fR | in the table signifies that an action should be taken as a consequence of the relevant fault condition. An \fIopen space\fR | in the table signifies that the relevant action should \fInot\fR be taken as a consequence of the relevant fault condition, if the condition is the only one present. If more than one fault condition is simultaneously present, the relevant action should be taken if, for at least one of the conditions, a \fIYes\fR is defined in relation to this action. .nr PS 9 .RT .ad r \fBTable 1/G.736 [T1.736], p.\fR .sp 1P .RT .ad b .RT .LP .bp .sp 2P .LP \fB5\fR \fBInterfaces\fR .sp 1P .RT .PP The digital interfaces at 2048 kbit/s should be in accordance with Recommendation\ G.703. .PP The digital interfaces at 64 kbit/s should be of either the codirectional or the contradirectional type specified in Recommendation\ G.703. The interface for external synchronization of the transmitting timing signal should be in accordance with\ G.703. .PP \fINote\ 2\fR \ \(em\ In the case of the 64 kbit/s codirectional interface, the design of the input ports should take account of the need to provide octet alignment, to allow controlled slips when the tributary timing and that of the multiplexer timing source are plesiochronous, and to absorb jitter and wander up to the limits given in Recommendation\ G.823. .RT .LP \fB6\fR \fBJitter\fR .sp 1P .RT .sp 2P .LP 6.1 \fIJitter at 2048\ kbit/s output\fR .sp 1P .RT .PP 6.1.1 In the case where the transmitting timing signal is derived from an internal oscillator, the peak\(hyto\(hypeak jitter at the 2048\ kbit/s output should not exceed\ 0.05\ UI when it is measured within the frequency range from \fIf\fR\d1\u\ =\ 20\ Hz to \fIf\fR\d4\u\ =\ 100\ kHz. See Figure\ 2/G.823. .sp 9p .RT .PP 6.1.2 In the case where the transmitting timing signal is derived from an external source having no jitter, the peak\(hyto\(hypeak jitter at the 2048\ kbit/s output should not exceed 0.05\ UI when it is measured within the frequency range from \fIf\fR\d1\u\ =\ 20\ Hz to\ \fIf\fR\d4\u\ =\ 100\ kHz. .PP 6.1.3 In the case where the transmitting timing signal is derived from the incoming 2048 kbit/s signal having no jitter, the peak\(hyto\(hypeak jitter at the 2048\ kbit/s output should not exceed 0.10\ UI when it is measured within the frequency range from\ \fIf\fR\d1\u\ =\ 20\ Hz to\ \fIf\fR\d4\u\ =\ 100\ kHz. The equivalent binary content of the test signal applied at the 2048\ kbit/s input shall be a pseudo\(hyrandom bit sequence of length 2\u1\d\u5\d\(em1 as specified in Recommendatoin\ O.151. .PP \fINote\fR \ \(em\ It may be necessary to include a frame alignment signal in the test signal to enable the measurement to be carried out. .sp 1P .LP 6.2 \fIJitter at 64 kbit/s output\fR .sp 9p .RT .PP In the case where the incoming 2048 kbit/s signal has no jitter, the peak\(hyto\(hypeak jitter at the 64\ kbit/s output should not exceed 0.025\ UI when it is measured within the frequency range from \fIf\fR\d1\u\ =\ 20\ Hz to \fIf\fR\d4\u\ =\ 10\ kHz. The equivalent binary content of the test signal applied to the 2048\ kbit/s input shall be a pseudo\(hyrandom bit sequence of length\ 2\u1\d\u5\d \(em1 as specified in Recommendation\ O.151. .PP \fINote\fR \ \(em\ In order to carry out this measurement without invoking AIS at the 64\ kbit/s output, it will normally be necessary to include a frame alignment signal in the test signal. .RT .sp 2P .LP 6.3 \fIJitter transfer functions\fR .sp 1P .RT .PP 6.3.1 The jitter transfer function between the 2048\ kHz external synchronisation signal and the 2048\ kbit/s output signal should not exceed the gain/frequency limits given in Figure\ 1/G.736. The 2048\ kHz signal shall be modulated with sinusoidal jitter. .sp 9p .RT .PP Some Administrations require that equipment be fitted with jitter reducers. In this case, the jitter transfer function should not exceed the gain/frequency limits given in Figure\ 2/G.736. .PP 6.3.2 In the case where the transmitting timing is derived from the incoming signal, the jitter transfer junction between the 2048\ kbit/s input and 2048\ kbit/s output shall be as specified in \(sc\ 6.3.1. .sp 9p .RT .PP \fINote\ 1\fR \ \(em\ The 2048 kbit/s test signal shall be modulated by sinusoidal jitter. The equivalent binary content of the test signal shall be\ 1000. .PP \fINote\ 2\fR \ \(em\ It may be necessary to include a frame alignment signal in the test signal to enable the measurement to be carried out. .RT .PP 6.3.3 The jitter transfer function between the 2048\ kbit/s and the 64\ kbit/s output should not exceed \(em29.6\ dB when measured over the frequency range\ \fIf\fR\d0\uto 10\ kHz. The frequency\ \fIf\fR\d0\ushould be less than 20\ Hz and as low as possible (e.g.\ 10\ Hz), taking into account the limitations of measuring equipment. .bp .sp 9p .RT .PP \fINote\ 1\fR \ \(em\ The 2048 kbit/s test signal shall be modulated by sinusoidal jitter. The equivalent binary content of the test signal shall be\ 1000. .PP \fINote\ 2\fR \ \(em\ In order to carry out this measurement without invoking AIS at the 64\ kbit/s output, it will normally be necessary to include a frame alignment signal in the test signal. .PP \fINote\ 3\fR \ \(em\ The jitter reduction of 1/32 due to demultiplexing is equivalent to \(em30.1\ dB. .RT .LP .rs .sp 24P .ad r \fBFigure 1/G.736, p.\fR .sp 1P .RT .ad b .RT .LP .rs .sp 23P .ad r \fBFigure 2/G.736, p.\fR .sp 1P .RT .ad b .RT .LP .bp .sp 2P .LP \fBRecommendation\ G.737\fR .RT .sp 2P .ce 1000 \fBCHARACTERISTICS\ OF\ AN\ \fR \fBEXTERNAL\ ACCESS\ EQUIPMENT\fR .EF '% Fascicle\ III.4\ \(em\ Rec.\ G.737'' .OF '''Fascicle\ III.4\ \(em\ Rec.\ G.737 %' .ce 0 .ce 1000 \fBOPERATING\ AT\ 2048\ kbit/s\ OFFERING\ SYNCHRONOUS\fR .ce 0 .sp 1P .ce 1000 \fBDIGITAL\ ACCESS\ AT\ 384\ kbit/s\ AND/OR\ 64\ kbit/s\fR .ce 0 .sp 1P .ce 1000 \fI(former Recommendation G.739 of Volume III of the Yellow Book)\fR .sp 9p .RT .ce 0 .sp 1P .PP This Recommendation gives the characteristics of equipment (external to PCM muldexes) operating at 2048\ kbit/s and providing one or several of the following tributaries into/from channel time slots of a 2048\ kbit/s composite signal: .sp 1P .RT .LP \(em bidirectional synchronous 64\ kbit/s access (Figure\ 1a/G.737); .LP \(em unidirectional synchronous 384\ kbit/s access (Figure\ 1b/G.737). .PP The 384\ kbit/s channel is based on the allocation of 6\ \(mu\ 64\ kbit/s time slots, e.g. for setting up sound\(hyprogramme circuits according to Recommendations\ J.41 and J.42. Because these circuits are specified as unidirectional the equipment for insertion/extraction has to be separated as shown in Figure\ 1b/G.737. .LP .rs .sp 34P .ad r \fBFigure 1/G.737, p. 16\fR .sp 1P .RT .ad b .RT .LP .bp .sp 2P .LP \fB1\fR \fBGeneral characteristics\fR .sp 1P .RT .sp 1P .LP 1.1 \fIBit rate\fR .sp 9p .RT .PP The nominal bit rate is 2048\ kbit/s. The tolerance on this rate is \(+- | 0 parts per million (ppm). .RT .sp 1P .LP 1.2 \fITypes of\fR \fIexternal access\fR \v'3p' .sp 9p .RT .LP a) Bidirectional synchronous insertion/extraction of 64\ kbit/s data channels (see Figure\ 1a/G.737). .LP \fINote\ 1\fR \ \(em\ The timing signal for the insertion side should be derived from the 2048\ kbit/s incoming signal at the insertion side (I\d0\u): the timing signal for the extraction side should be derived from the 2048\ kbit/s incoming signal at the extraction side (E\d1\u). .LP \fINote\ 2\fR \ \(em\ The provision of a timing signal output, available for the purpose of synchronizing other equipments, is an option that might be required depending upon national synchronization arrangements. .LP \fINote\ 3\fR \ \(em\ Further study is required on the possible need for an internal clock. .LP b) Unidirectional synchronous insertion and extraction of a digital sound\(hyprogramme signal into/out of a 384\ kbit/s channel (see Figure\ 1b/G.737). .LP \fINote\fR \ \(em\ The synchronous insertion equipment for 384\ kbit/s signals requires the internal regeneration of a timing signal synchronized by the 2048\ kbit/s input signal I\d0\u. This timing signal output of the synchronous insertion equipment is used for synchronizing the sampling frequency of the analogue/digital converter. .sp 2P .LP \fB2\fR \fBFrame structure\fR \fBand use of \fR \fBderived channel time\fR \fBslots\fR .sp 1P .RT .sp 1P .LP 2.1 \fIFrame structure of the 2048\ kbit/s signal\fR .sp 9p .RT .PP Refer to \(sc\ 2.3 of Recommendation\ G.704. Bit\ 1 of the frame should be used in accordance with\ \(sc\ 2.3.3 of Recommendation\ G.704, i.e. for a CRC check bit procedure. .RT .sp 1P .LP 2.2 \fIUse of derived channel time slots\fR .sp 9p .RT .PP Time slots not accessed flow transparently through the equipment. .PP \fINote\fR \ \(em\ Further study is required as to whether the binary content of time slots used at the access points should be replaced, after extraction from the composite signal, by the AIS. .RT .sp 1P .LP 2.2.1 \fI64\ kbit/s access\fR .sp 9p .RT .PP The number of accessible channel time slots should be at least four and the equipment shall allow access to any of channel time slots\ 1 to\ 15 and\ 17 to\ 31. .PP \fINote\fR \ \(em\ Equipment exists which provides access to at least four channel time slots in the following order of priority: 6 \(em 22 \(em 14 \(em 30 \(em 2 \(em 18 \(em 10 \(em 26 \(em 4 \(em 20 \(em 12 \(em 28 \(em 8 \(em 24 \(em 5 \(em 21 \(em 13 \(em 29\ \(em 1 \(em 17 \(em 9 \(em 25 \(em 3 \(em 19 \(em 11 \(em 27 \(em 7 \(em 23 \(em 15 \(em\ 31. .RT .sp 1P .LP 2.2.2 \fI384\ kbit/s access\fR .sp 9p .RT .PP The time slot allocation for digital channels with a bit rate at\ 384\ kbit/s is given in Table\ 1/G.737. .RT .ce \fBH.T. [T1.737]\fR .ce TABLE\ 1/G.737 .ps 9 .vs 11 .nr VS 11 .nr PS 9 .TS center box; cw(36p) sw(30p) sw(36p) sw(30p) sw(36p) | cw(60p) , c | c | c | c | c | ^ . 384 kbit/s channels (Note 1) { Digital sound\(hyprogramme access points } A B C D E _ .T& cw(36p) | cw(30p) | cw(36p) | cw(30p) | cw(36p) | cw(60p) . 1\(hy2\(hy3 4\(hy5\(hy6 7\(hy8\(hy9 10\(hy11\(hy12 13\(hy14\(hy15 I3, T, E3 .T& cw(36p) | cw(30p) | cw(36p) | cw(30p) | cw(36p) | cw(60p) . 17\(hy18\(hy19 20\(hy21\(hy22 23\(hy24\(hy25 26\(hy27\(hy28 29\(hy30\(hy31 Figure 1b/G.735 .TE .LP \fINote\ 1\fR \ \(em\ The five possible 384 kbit/s channels in a 2048 kbit/s stream are numbered A to E. Preferably the channel pairs A\(hyB and C\(hyD should be used for stereophonic transmission. .LP \fINote\ 2\fR \ \(em\ If the channel time slot 16 which is assigned to signalling as covered in \(sc\ 5 is not needed for signalling, it may be used for purposes other than a voice channel encoded within the PCM multiplex equipment. .nr PS 9 .RT .ad r \fBTable 1/G.737 [T1.737], p. \fR .sp 1P .RT .ad b .RT .LP .bp .sp 2P .LP \fB3\fR \fBFrame alignment and CRC procedures both at insertion (I\fR\(da\fB0) and extraction (E\fR\(da\fB1) sides\fR .sp 1P .RT .PP An illustration of the procedure is given in Figure\ 2/G.706. .RT .sp 1P .LP 3.1 \fILoss of frame alignment\fR .sp 9p .RT .PP Refer to \(sc 4.1.1 of Recommendation\ G.706. .RT .sp 1P .LP 3.2 \fIRecovery of frame alignment\fR .sp 9p .RT .PP Refer to \(sc 4.1.2 of Recommendation\ G.706. .RT .sp 1P .LP 3.3 \fICRC multiframe alignment in TSO\fR .sp 9p .RT .PP Refer to \(sc 4.2 of Recommendation\ G.706. .RT .sp 1P .LP 3.4 \fICRC bit monitoring\fR .sp 9p .RT .PP Refer to \(sc 4.3 of Recommendation\ G.706. .RT .sp 2P .LP \fB4\fR \fBFault conditions\fR \fBand consequent actions\fR .sp 1P .RT .sp 1P .LP 4.1 \fIFault conditions\fR .sp 9p .RT .PP The equipment should detect the following fault conditions: .RT .PP 4.1.1 Failure of power supply. .sp 9p .RT .PP 4.1.2 Loss of incoming signal at I\d2\uor \d3\u. .sp 9p .RT .PP \fINote\fR \ \(em\ This detection is not mandatory when contradirectional interfaces are used. .PP 4.1.3 Loss of the incoming signal at 2048\ kbit/s both at insertion (I\d0\u) and extraction (E\d1\u) sides. .sp 9p .RT .PP \fINote\ 1\fR \ \(em\ The detection of this fault condition is required only when it does not result in an indication of loss of frame alignment. .PP \fINote\ 2\fR \ \(em\ Where separate circuits are used for the digital signal and the timing signal, the loss of either or both should constitute loss of the incoming signal. .RT .PP 4.1.4 Loss of frame alignment both at insertion (I\d0\u) and extraction (E\d1\u) sides. .sp 9p .RT .PP 4.1.5 Excessive bit error ratio detected by monitoring the frame alignment signal at both the insertion (I\d0\u) and extraction (E\d1\u) sides. .sp 9p .RT .PP \fINote\fR \ \(em\ The detection of this fault condition at insertion side (I\d0\u) depends on the type of application of this equipment in a network and therefore is not mandatory. .PP 4.1.5.1 With a random bit error ratio of \(=10\uD\dlF261\u4\d, the probability of activating the indication of fault condition within a few seconds should be less than 10\uD\dlF261\u6\d. .sp 9p .RT .PP With a random bit error ratio of \(>="10\uD\dlF261\u3\d, the probability of activating the indication of fault condition within a few seconds should be higher than\ 0.95. .PP 4.1.5.2 With a random bit error ratio of \(>="10\uD\dlF261\u3\d, the probability of deactivating the indication of fault condition within a few seconds should be almost\ 0. .sp 9p .RT .PP With a random bit error ratio of \(=10\uD\dlF261\u4\d, the probability of deactivating the indication of fault condition within a few seconds should be higher than\ 0.95. .PP \fINote\fR \ \(em\ The activating and the deactivating period specified as \*Qa few seconds\*U is intended to be in the order of 4 to 5\ seconds. .bp .RT .sp 1P .LP 4.2 \fIConsequent actions\fR .sp 9p .RT .PP Further to the detection of a fault condition, appropriate actions should be taken as specified in Table\ 2/G.737. The consequent actions are as follows: .RT .PP 4.2.1 Prompt maintenance alarm indication generated to signify that performance is below acceptable standards and maintenance attention is required locally. When the AIS at the 2048\ kbit/s inputs (I\d0\u, E\d1\u) is detected (see General Notes below to \(sc\ 4.2), the prompt maintenance alarm indication associated with loss of frame alignment (see \(sc\ 4.1.4) and excessive error ratio (see \(sc\ 4.1.5) should be inhibited, while the rest of the consequent actions are in accordance with those associated in Table\ 2/G.737 with the two fault conditions. .sp 9p .RT .PP \fINote\fR \ \(em\ The location and provision of any visual and/or audible alarm activated by the alarm indications given in \(sc\ 4.2.1 is left to the discretion of each Administration. .PP 4.2.2 AIS applied to E\d2\uor \d3\uoutputs (see General Notes below to \(sc\ 4.2). This action should be taken as soon as possible and not later than 2\ ms after the detection of the fault condition. .sp 9p .RT .PP 4.2.3 AIS applied to relevant time slots in the composite 2048\ kbit/s output signal at insertion side (I\d1\u) if supervision of the incoming I\d2\uand I\d3\usignal is provided. .sp 9p .RT .PP 4.2.4 Inhibition of I\d2\uor \d3\udigital information insertion. .sp 9p .RT .PP 4.2.5 Both 2048\ kbit/s signals are bypassed. .sp 9p .RT .PP \fINote\fR \ \(em\ The provision of this consequent action depends on the type of application of this equipment in a network and therefore is not mandatory. .PP 4.2.6 AIS applied to the 2048\ kbit/s output, extraction side (E\d0\u). .sp 9p .RT .PP \fINote\fR \ \(em\ The provision of this consequent action depends on the type of application of this equipment in a network and therefore is not mandatory. .PP 4.2.7 AIS applied to the 2048\ kbit/s output, insertion side (I\d1\u). .sp 9p .RT .PP \fINote\fR \ \(em\ The provision of this consequent action depends on the type of this equipment in a network and therefore is not mandatory. .sp 1P .LP \fIGeneral Note to \(sc\ 4.2\fR .sp 9p .RT .PP \fINote\ 1\fR \ \(em\ The equivalent binary content of the alarm indication signal (AIS) is a continuous stream of binary\ 1s. The strategy for detecting the presence of the AIS should be such that with a high probability the AIS is detectable even in the presence of random errors having a mean error ratio\ 1 | (mu | 0\uD\dlF261\u3\d. Nevertheless, a signal in which all the binary elements, with the exception of the frame alignment signal, are in the state\ 1, should not be taken as an AIS. .PP \fINote\ 2\fR \ \(em\ All timing requirements quoted apply equally to restoration, subsequent to the fault condition clearing. .RT .sp 2P .LP \fB5\fR \fBInterfaces\fR .sp 1P .RT .PP The digital interfaces at 2048\ kbit/s should be in accordance with Recommendation\ G.703. .PP The digital interfaces at 64\ kbit/s should be either of the codirectional or the contradirectional type specified in Recommendation\ G.703. .PP The need to define a digital interface operating at 384\ kbit/s is under study. .PP \fINote\ 1\fR \ \(em\ It should be noted that according to the principle of minimizing the number of different types of interfaces, the information rate of 384\ kbit/s will be offered to customers at the user/network interface level using the 2048\ kbit/s interface as defined in Recommendations\ I.431 and\ G.703. .PP \fINote\ 2\fR \ \(em\ In the case of the 64\ kbit/s codirectional interface, the design of the input ports should take account of the need to provide octet alignment, to allow controlled slips when the tributary timing and that of the multiplexer timing source are plesiochronous, and to absorb jitter and wander up to the limits given in Recommendation\ G.823. .bp .RT .ce \fBH.T. [T2.737]\fR .ps 9 .vs 11 .nr VS 11 .nr PS 9 .TS center box; cw(342p) . TABLE\ 2/G.737 .T& cw(342p) . { \fBFault conditions and consequent actions for the external access\fR \fBequipment\fR } .TE .TS center box; cw(60p) | cw(36p) sw(36p) sw(36p) sw(48p) | cw(42p) | cw(42p) | cw(42p) , ^ | c | c | c | c | ^ | ^ | ^ . { Fault conditions (see \(sc\ 4.1) } { Consequent actions (see \(sc\ 4.2) } { Both 2048 kbit/s signal are bypassed (see Note under \(sc\ 4.2.5) } { AIS applied to the 2048\ kbit/s output, extraction side (E 0) (see Note under \(sc\ 4.2.6) } { AIS applied to the 2048\ kbit/s output, insertion side (I 1) (see Note under \(sc\ 4.2.7) } { Prompt maintenance alarms indication generated } { AIS applied to E 2 or E 3 outputs } { Inhibition of digital information insertion I 2, I 3 } { AIS applied to the relevant time slot of the 2048\ kbit/s composite signal at insertion side (I 1) } _ .T& cw(60p) | cw(36p) | lw(36p) | lw(36p) | lw(48p) | cw(42p) | cw(42p) | cw(42p) . Failure of power supply Yes Yes Yes (if practicable) Yes (if practicable) _ .T& cw(60p) | cw(36p) | lw(36p) | lw(36p) | cw(48p) | cw(42p) | cw(42p) | cw(42p) . { Loss of incoming signal at I 2 or I 3 inputs (see Note under \(sc\ 4.1.2) } Yes Yes _ .T& cw(30p) | cw(30p) | cw(36p) | cw(36p) | cw(36p) | cw(48p) | cw(42p) | cw(42p) | cw(42p) , ^ | l | l | l | l | l | l | l | l. { Loss of incoming signal at 2048\ kbit/s } Extr.s. (E 1) Yes Yes Yes Ins.s. (I 0) Yes Yes Yes _ .T& cw(30p) | cw(30p) | cw(36p) | cw(36p) | cw(36p) | cw(48p) | cw(42p) | cw(42p) | cw(42p) , ^ | l | l | l | l | l | l | l | l. { Loss of frame alignment (see Note 2 of Rec.\ G.706, \(sc\ 4.2) } Extr. s. (E 1) Yes (see \(sc\ 4.2.1) Yes Yes Ins. s. (I 0) Yes (see \(sc\ 4.2.1) Yes Yes _ .T& cw(30p) | cw(30p) | cw(36p) | cw(36p) | cw(36p) | cw(48p) | cw(42p) | cw(42p) | cw(42p) , ^ | l | l | l | l | l | l | l | l. { Error ratio 1.10\uD\dlF261\u3\d on the frame alignment signal (see Note under \(sc\ 4.1.5) } Extr.s. (E 1) Yes (see \(sc\ 4.2.1) Yes Yes Ins.s. (I 0) Yes (see \(sc\ 4.2.1) Yes Yes .TE .LP \fINote\fR \ \(em\ A \fIYes\fR | in the table signifies that an action should be taken as a consequence of the relevant fault condition. An \fIopen space\fR | n the table signifies that the relevant action should \fInot\fR | be taken as a consequence of the relevant fault condition, if this condition is the only one present. If more than one fault condition is simultaneously present, the relevant action should be taken if, for at least one of the conditions, a \fIYes\fR is defined in relation to this action. .nr PS 9 .RT .ad r \fBTable 2/G.737 [T2.737], p. \fR .sp 1P .RT .ad b .RT .LP .bp .sp 2P .LP \fB6\fR \fBJitter\fR .sp 1P .RT .sp 1P .LP 6.1 \fIJitter at 2048 kbit/s output\fR .sp 9p .RT .PP When there is no jitter on the 2048\ kbit/s inputs (I\d0\u, E\d1\u) the peak\(hyto\(hypeak jitter at the 2048\ kbit/s outputs (I\d1\u, E\d0\u) should not exceed\ 0.10 UI when it is measured within the frequency range from \fIf\fR\d1\u\ =\ 20\ Hz to \fIf\fR\d4\u\ =\ 100\ kHz. The equivalent binary content of the test signal applied at the 2048\ kbit/s input shall be a pseudo\(hyrandom bit sequence of length 2\u1\d\u5\d\(em1 as specified in Recommendation\ O.151. See Figure\ 2/G.823. .PP \fINote\fR \ \(em\ It may be necessary to include a frame alignment signal in the test signal to enable the measurement to be carried out. .RT .sp 2P .LP 6.2 \fIJitter at E\fI .sp 1P .RT .EF '% \fI2\ and\'' .OF '''\fI2\ and\ %' .EF '% \fI3\ outputs'' .OF '''\fI3\ outputs %' .PP 6.2.1 The jitter at the E\d2\u(64\ kbit/s) output when there is no jitter at the 2048\ kbit/s input (E\d1\u) should not exceed 0.025 UI when measured within the frequency range from \fIf\fR\d1\u\ =\ 20\ Hz to \fIf\fR\d4\u\ =\ 10\ kHz. The equivalent binary content of the test signal applied at the 2048\ kbit/s input shall be a pseudo\(hyrandom bit sequence of length 2\u1\d\u5\d\(em1 as specified in Recommendation\ O.151. .sp 9p .RT .PP \fINote\fR \ \(em\ In order to carry out this measurement without invoking AIS at the 64\ kbit/s output, it will normally be necessary to include a frame alignment signal in the test signal. .PP 6.2.2 Since the physical and electrical characteristics of a 384\ kbit/s interface are identical to those of the 2048\ kbit/s interface, the jitter at the E\d3\u(synchronous 384\ kbit/s) output when there is no jitter at the 2048\ kbit/s input (E\d1\u) is according to\ \(sc\ 6.1 above. .sp 9p .RT .sp 2P .LP 6.3 \fIJitter transfer functions\fR .sp 1P .RT .PP 6.3.1 The jitter transfer function between the 2048\ kbit/s input (I\d0\u, \d1\u) and the output (I\d1\u, E\d0\u) should not exceed the gain/frequency limits given in Figure\ 2/G.737. .sp 9p .RT .PP Some Administrations require that equipment be fitted with jitter reducers . In this case, the jitter transfer function should not exceed the gain/frequency limits given in Figure\ 3/G.737. .PP \fINote\ 1\fR \ \(em\ The 2048\ kHz signal shall be modulated with sinusoidal jitter. The equivalent binary content of the test signal shall be\ 1000. .PP \fINote\ 2\fR \ \(em\ It may be necessary to include a frame alignment signal in the test signal to enable the measurement to be carried out. .RT .PP 6.3.2 The jitter transfer function between the 2048\ kbit/s input (E\d1\u) and the E\d2\u(64\ kbit/s) output should not exceed \(em29.6\ dB when measured over the frequency range \fIf\fR\d0\uto 10\ kHz. The frequency \fIf\fR\d0\ushould be less than 20\ Hz and as low as possible (e.g. 10\ Hz), taking into account the limitations of measuring equipment. .sp 9p .RT .PP \fINote\ 1\fR \ \(em\ The 2048 kbit/s test signal shall be modulated by sinusoidal jitter. The equivalent binary content of the test signal shall be\ 1000. .PP \fINote\ 2\fR \ \(em\ In order to carry out this measurement without invoking AIS at the 64\ kbit/s output, it will normally be necessary to include a frame alignment signal in the test signal. .PP \fINote\ 3\fR \ \(em\ The jitter reduction of 1/32 due to demultiplexing is equivalent to \(em30.1\ dB. .RT .PP 6.3.3 Since the physical and electrical characteristics of a 384\ kbit/s interface are identical to those of the 2048\ kbit/s interface, the jitter transfer function between the 2048\ kbit/s input (E\d1\u) and E\d3\u(synchronous 384\ kbit/s) output is according to\ \(sc\ 6.3.1 above. .sp 9p .RT .LP .rs .sp 4P .ad r Blanc .ad b .RT .LP .bp .LP .rs .sp 24P .ad r \fBFigure 2/G.737, p. \fR .sp 1P .RT .ad b .RT .LP .rs .sp 23P .ad r \fBFigure 3/G.737, p. \fR .sp 1P .RT .ad b .RT .LP .bp .sp 2P .LP \fBRecommendation\ G.738\fR .RT .sp 2P .ce 1000 \fBCHARACTERISTICS OF PRIMARY PCM MULTIPLEX EQUIPMENT\fR .EF '% Fascicle\ III.4\ \(em\ Rec.\ G.738'' .OF '''Fascicle\ III.4\ \(em\ Rec.\ G.738 %' .ce 0 .ce 1000 \fBOPERATING AT 2048 kbit/s AND OFFERING SYNCHRONOUS\fR .ce 0 .sp 1P .ce 1000 \fBDIGITAL ACCESS AT 320 kbit/s AND/OR 64 kbit/s\fR .ce 0 .sp 1P .ce 1000 \fI(Melbourne, 1988)\fR .sp 9p .RT .ce 0 .sp 1P .PP This Recommendation gives the characteristics of a PCM multiplex equipment operating at 2048 kbit/s and providing one or several of the following internal digital access options: .sp 1P .RT .LP \(em bidirectional synchronous 64\ kbit/s channels (see Figure\ 1a/G.738); .LP \(em unidirectional synchronous 320\ kbit/s channels (see Figure\ 1b/G.738). .PP The 320\ kbit/s channel is based on the allocation of 5\ \(mu\ 64\ kbit/s time slots, e.g. for setting up sound\(hyprogramme circuits according to Recommendations\ J.43 and\ J.44. Because these circuits are specified as unidirectional, the equipment for insertion/extraction has to be separated as shown in Figure\ 1b/G.738. .sp 2P .LP \fB1\fR \fBGeneral characteristics\fR .sp 1P .RT .sp 1P .LP 1.1 \fIFundamental characteristics for voice\(hychannel encoding\fR .sp 9p .RT .PP The encoding law used is the A\(hylaw as specified in Recommendation\ G.711. The sampling rate, load capacity and the code are also specified in that Recommendation. .PP The number of quantized values is\ 256. .PP \fINote\fR \ \(em\ The inversion of bits\ 2, 4, 6 and\ 8 is covered by the encoding law and is applicable only to voice\(hychannel time slots. .RT .sp 1P .LP 1.2 \fIBit rate\fR .sp 9p .RT .PP The nominal bit rate is 2048\ kbit/s. The tolerance on this rate is\ \(+-\ 50 parts per million (ppm). .RT .sp 1P .LP 1.3 \fITiming signal\fR .sp 9p .RT .PP It should be possible to derive the transmit timing signal from any of the following: .RT .LP a) from the received 2048 kbit/s signal; .LP b) from an external source at 2048 kHz (see\ \(sc\ 5); .LP c) from an internal oscillator. .PP \fINote\fR \ \(em\ The provision of a timing signal output, available for the purpose of synchronizing other equipments, is an option that might be required depending upon national synchronization arrangements. .sp 1P .LP 1.4 \fITypes of access\fR \v'3p' .sp 9p .RT .LP a) access for bidirectional synchronous 64\ kbit/s channels (see Figure\ 1a/G.738); .LP b) access for unidirectional synchronous 320\ kbit/s channels (see Figure\ 1b/G.738). .PP \fINote\fR \ \(em\ The synchronous insertion of a digital sound\(hyprogramme signal into a 320\ kbit/s channel requires the internal regeneration of a timing signal\ T synchronized by the 2048\ kbit/s signal I\d1\u. The timing signal is used for synchronizing the sampling frequency of the analogue/digital converters producing the digital sound\(hyprogramme signal. .sp 2P .LP \fB2\fR \fBFrame structure and use of derived channel time slots\fR .sp 1P .RT .sp 1P .LP 2.1 \fIFrame structure of 2048 kbit/s signal\fR .sp 9p .RT .PP Refer to \(sc\ 2.3 of Recommendation\ G.704. Bit\ 1 of the frame should be used in accordance with \(sc\ 2.3.3 of Recommendation\ G.704, i.e. for a CRC check bit procedure. .bp .RT .LP .rs .sp 34P .ad r \fBFIGURE 1/G.738, p.\fR .sp 1P .RT .ad b .RT .sp 2P .LP 2.2 \fIUse of derived channel time slots\fR .sp 1P .RT .sp 1P .LP 2.2.1 \fITelephone channels\fR .sp 9p .RT .PP It should be possible to assign channel time slots\ 1 to\ 15 and\ 17 to\ 31, to\ 30 telephone channels numbered from\ 1 to\ 30. .RT .sp 1P .LP 2.2.2 \fI64 kbit/s access\fR .sp 9p .RT .PP The number of accessible channel time slots should be at least four and the equipment shall allow access to any of channel time slots\ 1 to\ 15 and\ 17 to\ 31. .PP \fINote\fR \ \(em\ Equipment exists which provides access to at least four channel time slots in the following order of priority: 6 \(em 22 \(em 14 \(em 30 \(em 2 \(em 18 \(em 10 \(em 26 \(em 4 \(em 20 \(em 12 \(em 28 \(em 8 \(em 24 \(em 5 \(em 21 \(em 13 \(em 29 \(em 1\ \(em 17 \(em 9 \(em 25 \(em 3 \(em 19 \(em 11 \(em 27 \(em 7 \(em 23 \(em 15 \(em 31. .bp .RT .sp 1P .LP 2.2.3 \fI320 kbit/s access\fR .sp 9p .RT .PP The time slot allocation for digital channels with bit rate at 320\ kbit/s is given in Table\ 1/G.738. .RT .ce \fBH.T. [T1.738]\fR .ce TABLE\ 1/G.738 .ps 9 .vs 11 .nr VS 11 .nr PS 9 .TS center box; cw(34p) sw(34p) sw(28p) sw(34p) sw(34p) sw(28p) | cw(36p) , c | c | c | c | c | c | ^ . 320 kbit/s channels (Note 1) { Digital sound\(hyprogramme access points } A B C D E F _ .T& lw(34p) | lw(34p) | cw(28p) | cw(34p) | cw(34p) | cw(28p) | cw(36p) . { 1 \(hy 2 \(hy 3 \(hy 4 \(hy 5 } { 6 \(hy 7 \(hy 8 \(hy 9 \(hy 10 } { 11 \(hy 12 \(hy 13 \(hy 14 \(hy 15 } { 17 \(hy 18 \(hy 19 \(hy 20 \(hy 21 } { 22 \(hy 23 \(hy 24 \(hy 25 \(hy 26 } { 27 \(hy 28 \(hy 29 \(hy 30 \(hy 31 } { I3, T, E3 Figure\ 1b/G.738 } .TE .LP \fINote\ 1\fR \ \(em\ The six possible 320 kbit/s channels in a 2048\ kbit/s stream are numbered A to F. Preferably the channel pairs A\(hyB, C\(hyD and E\(hyF should be used for stereophonic transmission. .LP \fINote\ 2\fR \ \(em\ If the channel time slot 16 which is assigned to signalling as covered in \(sc\ 5 is not needed for signalling, it may be used for purposes other than a voice channel encoded within the PCM multiplex equipment. .nr PS 9 .RT .ad r \fBTable 1/G.738 [T1.738], p. \fR .sp 1P .RT .ad b .RT .sp 2P .LP \fB3\fR \fBFrame alignment and CRC procedures\fR .sp 1P .RT .PP An illustration of the procedure is given in Figure\ 2/G.706. .RT .sp 1P .LP 3.1 \fILoss of frame alignment\fR .sp 9p .RT .PP Refer to \(sc 4.1.1 of Recommendation\ G.706. .RT .sp 1P .LP 3.2 \fIRecovery of frame alignment\fR .sp 9p .RT .PP Refer to \(sc 4.1.2 of Recommendation G.706. .RT .sp 1P .LP 3.3 \fICRC multiframe alignment in TSO\fR .sp 9p .RT .PP Refer to \(sc 4.2 of Recommendation G.706. .RT .sp 1P .LP 3.4 \fICRC bit monitoring\fR .sp 9p .RT .PP Refer to \(sc 4.3 of Recommendation G.706. .RT .sp 2P .LP \fB4\fR \fBFault conditions and consequent actions\fR .sp 1P .RT .sp 1P .LP 4.1 \fIFault conditions\fR .sp 9p .RT .PP The PCM multiplex equipment should detect the following conditions: .RT .PP 4.1.1 Failure of power supply. .sp 9p .RT .PP 4.1.2 Failure of codec (except when using single channel codecs). .sp 9p .RT .PP As a minimum requirement, this fault condition should be recognized when for at least one signal level in the range \(em21 to \(em6\ dBm0, the signal\(hyto\(hyquantizing noise ratio performance of the local codec is 18\ dB or more below the level recommended in Recommendation\ G.712. .bp .PP 4.1.3 Loss of incoming signals at the 64\ kbit/s and 320\ kbit/s tributary input ports. .sp 9p .RT .PP \fINote\ 1\fR \ \(em\ This detection is not mandatory when contradirectional interfaces are used. .PP \fINote\ 2\fR \ \(em\ The detection of this fault condition is not mandatory for channel time slot\ 16 when channel associated signalling is used and the signalling multiplex equipment is situated within a few metres of the PCM multiplex equipment. .RT .PP 4.1.4 Loss of the incoming signal at 2048 kbit/s. .sp 9p .RT .PP \fINote\ 1\fR \ \(em\ The detection of this fault condition is required only when it does not result in an indication of loss of frame alignment. .PP \fINote\ 2\fR \ \(em\ Where separate circuits are used for the digital signal and the timing signal, the loss of either or both should constitute loss of the incoming signal. .RT .PP 4.1.5 Loss of frame alignment. .sp 9p .RT .PP 4.1.6 Excessive bit error ratio detected by monitoring the frame alignment signal. .sp 9p .RT .PP 4.1.6.1 With a random bit error ratio of \(=\ 10\uD\dlF261\u4\d, the probability of activating the indication of fault condition within a few seconds should be less than 10\uD\dlF261\u6\d. .sp 9p .RT .PP With a random bit error ratio of \(>="\ 10\uD\dlF261\u3\d, the probability of activating the indication of fault condition within a few seconds should be higher than\ 0.95. .PP 4.1.6.2 With a random bit error ratio of \(>="\ 10\uD\dlF261\u3\d, the probability of deactivating the indication of fault condition within a few seconds should be almost\ 0. .sp 9p .RT .PP With a random bit error ratio of \(=\ 10\uD\dlF261\u4\d, the probability of deactivating the indication of fault condition within a few seconds should be higher than\ 0.95. .PP \fINote\fR \ \(em\ The activating and deactivating period specified as \*Qa few seconds\*U is intended to be in the order of\ 4 to\ 5 seconds. .RT .PP 4.1.7 Alarm indication received from the remote PCM multiplex equipment (see\ \(sc\ 4.2.3). .sp 9p .RT .sp 1P .LP 4.2 \fIConsequent actions\fR .sp 9p .RT .PP Further to the detection of a fault condition, appropriate actions should be taken as specified in Table\ 2/G.738. The consequent actions are as follows: .RT .PP 4.2.1 Service alarm indication generated to signify that the service provided by the PCM multiplex is no longer available. This indication should be forwarded at least to the switching and/or signalling multiplex equipment depending upon the arrangements provided. The indication should be given as soon as possible and not later than\ 2\ ms after detection of the relevant fault condition. .sp 9p .RT .PP This specification, taking into account the specification given in \(sc\ 4.2.5, is equivalent to recommending that the average time to detect a loss of frame alignment or a loss of the incoming 2048\ kbit/s signal and to give the relevant indication should not be greater than\ 3\ ms. .PP When using common channel signalling the indication should be forwarded to the switching equipment by means of separate interface on the PCM multiplex equipment. .RT .PP 4.2.2 Prompt maintenance alarm indication generated to signify that performance is below acceptable standards and maintenance attention is required locally. When the AIS at 2048\ kbit/s input is detected (see General Notes below to\ \(sc\ 4.2), the prompt maintenance alarm indication associated with loss of frame alignement (see \(sc\ 4.1.5) and excessive error ratio (see \(sc\ 4.1.6) should be inhibited, while the rest of the consequent actions are in accordance with those associated in Table\ 2/G.738 with the two fault conditions. .sp 9p .RT .PP \fINote\fR \ \(em\ The location and provision of any visual and/or audible alarm activated by the alarm indications given in\ \(sc\ 4.2.1 and\ \(sc\ 4.2.2, is left to the discretion of each Administration. .PP 4.2.3 Alarm indication to the remote end, transmitted by changing bit\ 3 of channel time slot\ 0 from the state\ 0 to the state\ 1 in those frames not containing the frame alignment signal. This should be effected as soon as possible. .bp .sp 9p .RT .ce \fBH.T. [T2.738]\fR .ce TABLE\ 2/G.738 .ce \fBFault conditions and consequent actions for the\fR .ce \fBPCM multiplex equipment\fR .ps 9 .vs 11 .nr VS 11 .nr PS 9 .TS center box; cw(30p) | cw(36p) | cw(30p) sw(24p) sw(30p) sw(24p) sw(30p) sw(24p) , ^ | ^ | l | l | l | l | l | l. Equipment part { Fault conditions (see \(sc\ 4.1) } { Consequent actions (see \(sc\ 4.2) Service alarm indication generated Prompt maintenance alarm indication Alarm indication remote end transmitted Transmission suppressed at the analogue voice\(hyfrquency outputs AIS applied to 64\ kbit/s and 320\ kbit/s outputs AIS applied to the relevant time slot of the 2048\ kbit/s composite signal } _ .T& lw(30p) | lw(36p) | cw(30p) | cw(24p) | cw(30p) | cw(24p) | cw(30p) | cw(24p) , ^ | l | c | c | c | c | l | l. { Multiplexer and demulti plexer } Failure of power supply Yes Yes Yes (if practicable) Yes (if practicable) Yes (if practicable) Yes (if practicable) Failure of codec Yes Yes Yes Yes _ .T& lw(30p) | lw(36p) | cw(30p) | cw(24p) | cw(30p) | cw(24p) | cw(30p) | cw(24p) , ^ | l | c | c | c | c | l | l. Multiplexer only { Loss of incoming signal at 64\ kbit/s and/or 320\ kbit/s inputs (see Notes under \(sc\ 4.1.3) } Yes Yes _ .T& lw(30p) | lw(36p) | cw(30p) | cw(24p) | cw(30p) | cw(24p) | cw(30p) | lw(24p) , ^ | c | c | c | c | c | l | c ^ | c | c | c | c | l | c | l ^ | l | l | l | l | l | l | l. Demultiplexer only { Loss of incoming signal at 2048\ kbit/s } Yes Yes Yes Yes Yes { Loss of frame alignment (see Note 2 Rec.\ G.706, \(sc\ 4.2) } Yes Yes (see \(sc\ 4.2.2) Yes Yes Yes { Error ratio 1\(mu10\uD\dlF261\u3\d on the frame alignment signal } Yes Yes (see \(sc\ 4.2.2) Yes Yes Yes { Alarm indication received from the remote end } Yes .TE .LP \fINote\fR \ \(em\ A \fIYes\fR | in the table signifies that an action should be taken as a consequence of the relevant fault condition. An \fIopen space\fR in the table signifies that the relevant action should not be taken as a consequence of the relevant fault condition, if this condition is the only one present. If more than one fault condition is simultaneously present, the relevant action should be taken if, for at least one of the conditions, a \fIYes\fR is defined in relation to this action. .nr PS 9 .RT .ad r \fBTableau 2/G.738 [T2.738], p.\fR .sp 1P .RT .ad b .RT .LP .bp .PP 4.2.4 Transmission suppressed at the analogue voice\(hyfrequency outputs. .sp 9p .RT .PP 4.2.5 AIS applied to all 64\ kbit/s and 320\ kbit/s outputs (see General Notes below to\ \(sc\ 4.2). For 64\ kbit/s outputs this actions should be taken as soon as possible and not later than\ 2\ ms after the detection of the fault condition. .sp 9p .RT .PP 4.2.6 AIS applied to relevant time slots in the composite 2048\ kbit/s output signal (if suspension of incoming 64\ kbit/s and 320\ kbit/s signals is provided). .sp 9p .RT .sp 1P .LP \fIGeneral Notes to \(sc\ 4.2\fR .sp 9p .RT .PP \fINote\ 1\fR \ \(em\ The equivalent binary content of the alarm indication signal (AIS) is a continuous stream of binary\ 1s. The strategy for detecting the presence of AIS should be such that with a high probability the AIS is detectable even in the presence of random errors having a mean error rate of\ 1 in\ 10\u3\d. Nevertheless, a signal in which all the binary elements, with the exception of the frame alignment signal, are in the state\ 1, should not be taken as an AIS. .PP \fINote\ 2\fR \ \(em\ All timing requirements quoted apply equally to restoration, subsequent to the fault condition clearing. .RT .sp 2P .LP \fB5\fR \fBSignalling\fR .sp 1P .RT .PP Text as in Recommendation\ G.732. .RT .sp 2P .LP \fB6\fR \fBInterfaces\fR .sp 1P .RT .sp 1P .LP 6.1 \fIAudio frequency interface\fR .sp 9p .RT .PP The analogue audio frequency interfaces should be in accordance with Recommendations\ G.712, G.713, G.714 and G.715. .RT .sp 1P .LP 6.2 \fIDigital interfaces\fR .sp 9p .RT .PP The digital interfaces at 2048\ kbit/s should be in accordance with Recommendation\ G.703. .PP The digital interfaces at 64\ kbit/s should be of either the codirectional or the contradirectional type specified in Recommendation\ G.703. The specification for 64\ kbit/s interfaces are not mandatory for channel\(hyassociated signalling. The interface for external synchronization of the transmitting timing signal should be in accordance with Recommendation\ G.703. .PP The need to define a digital interface operating at 320\ kbit/s is under study. .PP \fINote\ 1\fR \ \(em\ It should be noted that, according to the principle of minimizing the number of different types of interfaces, the information rate of 320\ kbit/s will be offered to customers at the user/network interface level using the 2048\ kbit/s interface as defined in Recommendation\ I.431 and Recommendation\ G.703. .PP \fINote\ 2\fR \ \(em\ In the case of the 64\ kbit/s codirectional interface, the design of the input ports should take into account the need to provide octet alignment, to allow controlled slips when the tributary timing and that of the multiplexer timing source are plesiochronous, and to absorb jitter and wander up to the limits given in Recommendation\ G.823. .RT .LP \fB7\fR \fBJitter\fR .sp 1P .RT .sp 2P .LP 7.1 \fIJitter at 2048 kbit/s output\fR .sp 1P .RT .PP 7.1.1 In the case where the transmitting timing signal is derived from an internal oscillator, the peak\(hyto\(hypeak jitter at the 2048\ kbit/s output should not exceed 0.05\ UI when it is measured within the frequency range from \fIf\fR\d1\u\ =\ 20\ Hz to \fIf\fR\d4\u\ =\ 100\ kHz. See Figure\ 2/G.823. .sp 9p .RT .PP 7.1.2 In the case where the transmitting timing signal is derived from an external source having no jitter, the peak\(hyto\(hypeak jitter at the 2048\ kbit/s output should not exceed 0.05\ UI when it is measured within the frequency range from \fIf\fR\d1\u\ =\ 20\ Hz to \fIf\fR\d4\u\ =\ 100\ kHz. .bp .PP 7.1.3 In the case where the transmitting timing signal is derived from the incoming 2048\ kbit/s signal having no jitter, the peak\(hyto\(hypeak jitter at the 2048\ kbit/s output should not exceed 0.10\ UI when it is measured within the frequency range from \fIf\fR\d1\u\ =\ 20\ Hz to \fIf\fR\d4\u\ =\ 100\ kHz. The equivalent binary content of the test signal applied at the 2048\ kbit/s input shall be a pseudo\(hyrandom bit sequence of length 2\u1\d\u5\d\(em1 as specified in Recommendation\ O.151. .PP \fINote\fR \ \(em\ It may be necessary to include a frame alignment signal in the test signal to enable the measurement to be carried out. .sp 2P .LP 7.2 \fIJitter at tributary outputs\fR .sp 1P .RT .sp 1P .LP 7.2.1 \fIJitter at 64 kbit/s output\fR .sp 9p .RT .PP In the case where the incoming 2048\ kbit/s signal has no jitter, the peak\(hyto\(hypeak jitter at the 64\ kbit/s output should not exceed 0.025\ UI when it is measured within the frequency range from \fIf\fR\d1\u\ =\ 20\ Hz to \fIf\fR\d4\u\ =\ 10\ kHz. The equivalent binary content of the test signal applied to the 2048\ kbit/s input shall be a pseudo\(hyrandom bit sequence of length 2\u1\d\u5\d\(em1 as specified in Recommendation\ O.151. .PP \fINote\fR \ \(em\ In order to carry out this measurement without invoking AIS at the 64\ kbit/s output it will normally be necessary to include a frame alignment signal in the test signal. .RT .sp 1P .LP 7.2.2 \fIJitter at 320 kbit/s output\fR .sp 9p .RT .PP Since the physical and electrical characteristics of a 320\ kbit/s interface are identical to those of the 2048\ kbit/s interface, the specification of this parameter is the same as that given in\ \(sc\ 7.1.3 above. .RT .sp 2P .LP 7.3 \fIJitter transfer functions\fR .sp 1P .RT .PP 7.3.1 The jitter transfer function between the 2048\ kbit/s external synchronization signal and the 2048\ kbit/s output signal should not exceed the gain/frequency limits given in Figure\ 2/G.738. The 2048\ kHz signal shall be modulated with sinusoidal jitter. .sp 9p .RT .PP Some Administrations require that equipment be fitted with jitter reducers. In this case, the jitter transfer functions should not exceed the gain/frequency limits given in Figure\ 3/G.738. .PP 7.3.2 In the case where the transmitting timing is derived from the incoming signal, the jitter transfer function between the 2048\ kbit/s input and the 2048\ kbit/s output shall be as specified in\ \(sc\ 7.3.1. .sp 9p .RT .PP \fINote\ 1\fR \ \(em\ The 2048 kbit/s test signal shall be modulated by sinusoidal jitter. The equivalent binary content of the test signal shall be\ 1000. .PP \fINote\ 2\fR \ \(em\ It may be necessary to include a frame alignment signal in the test signal to enable the measurement to be carried out. .RT .PP 7.3.3 The jitter transfer function between the 2048\ kbit/s input and the 64\ kbit/s output should not exceed \(em29.6\ dB when measured over the frequency range \fIf\fR\d0\uto\ 10\ kHz. The frequency \fIf\fR\d0\ushould be less than 20\ Hz and as low as possbile (e.g. 10\ Hz), taking into account the limitations of measuring equipment. .sp 9p .RT .PP \fINote\ 1\fR \ \(em\ The 2048 kbit/s test signal shall be modulated by sinusoidal jitter. The equivalent binary content of the test signal shall be\ 1000. .PP \fINote\ 2\fR \ \(em\ In order to carry out this measurement without invoking AIS at the 64\ kbit/s output, it will normally be necessary to include a frame alignement signal in the test signal. .PP \fINote\ 3\fR \ \(em\ The jitter reduction of 1/32 due to demultiplexing is equivalent to \(em30.1\ dB. .RT .PP 7.3.4 Since the physical and electrical characteristics of a 320\ kbit/s interface are identical to those of 2048\ kbit/s interface, the jitter transfer function between 2048\ kbit/s input and 320\ kbit/s output is the same as that given in\ \(sc\(sc\ 7.3.1 and 7.3.2 above. .bp .sp 9p .RT .LP .rs .sp 24P .ad r \fBFigure 2/G.738, p. \fR .sp 1P .RT .ad b .RT .LP .rs .sp 22P .ad r \fBFigure 3/G.738, p. \fR .sp 1P .RT .ad b .RT .LP .bp .sp 2P .LP \fBRecommendation\ G.739\fR .RT .sp 2P .ce 1000 \fBCHARACTERISTICS\ OF\ AN\ EXTERNAL\ ACCESS\ EQUIPMENT\fR .EF '% Fascicle\ III.4\ \(em\ Rec.\ G.739'' .OF '''Fascicle\ III.4\ \(em\ Rec.\ G.739 %' .ce 0 .ce 1000 \fBOPERATING\ AT\ 2048\ kbit/s\ OFFERING\ SYNCHRONOUS\fR .ce 0 .sp 1P .ce 1000 \fBDIGITAL\ ACCESS\ AT\ 320\ kbit/s\ AND/OR\ 64\ kbit/s\fR .ce 0 .sp 1P .ce 1000 \fI(Melbourne, 1988)\fR .sp 9p .RT .ce 0 .sp 1P .PP This Recommendation gives the characteristics of equipment (external to PCM muldexes) operating at 2048\ kbit/s and providing one or several of the following tributaries into/from channel time slots of a 2048\ kbit/s composite signal: .sp 1P .RT .LP \(em bidirectional synchronous 64\ kbit/s access (Figure\ 1a/G.739); .LP \(em unidirectional synchronous 320 kbit/s access (Figure\ 1b/G.739). .PP The 320 kbit/s channel is based on the allocation of 5\ \(mu\ 64\ kbit/s time slots, e.g. for setting up sound\(hyprogramme circuits according to Recommendations\ J.43 and\ J.44. Because these circuits are specified as unidirectional, the equipment for insertion/extraction has to be separated as shown in Figure\ 1b/G.739. .sp 2P .LP \fB1\fR \fBGeneral characteristics\fR .sp 1P .RT .sp 1P .LP 1.1 \fIBit rate\fR .sp 9p .RT .PP The nominal bit rate is 2048\ kbit/s. The tolerance on this rate is\ \(+-\ 50 parts per million (ppm). .RT .sp 1P .LP 1.2 \fITypes of external access\fR \v'3p' .sp 9p .RT .LP a) Bidirectional synchronous insertion/extraction of 64\ kbit/s data channels (see Figure\ 1a/G.739). .LP \fINote\ 1\fR \ \(em\ The timing signal for the insertion side should be derived from the 2048\ kbit/s incoming signal at the insertion side (I\d0\u); the timing signal for the extraction side should be derived from the 2048\ kbit/s incoming signal at the extraction side (E\d1\u). .LP \fINote\ 2\fR \ \(em\ The provision of a timing signal output, available for the purpose of synchronizing other equipments, is an option that might be required depending upon national synchronization arrangements. .LP \fINote\ 3\fR \ \(em\ Further study is required on the possible need for an internal clock. .LP b) Unidirectional synchronous insertion and extraction of a digital sound\(hyprogramme signal into/out of a 320\ kbit/s channel (see Figure\ 1b/G.739). .LP \fINote\fR \ \(em\ The synchronous insertion equipment for 320\ kbit/s signals requires the internal regeneration of a timing signal synchronized by the 2048\ kbit/s input signal I\d0\u. This timing signal output of the synchronous insertion equipment is used for synchronizing the sampling frequency of the analogue/digital converter. .sp 2P .LP \fB2\fR \fBFrame structure and use of derived channel time slots\fR .sp 1P .RT .sp 1P .LP 2.1 \fIFrame structure of the 2048 kbit/s signal\fR .sp 9p .RT .PP Refer to \(sc 2.3 of Recommendation\ G.704. Bit\ 1 of the frame should be used in accordance with \(sc\ 2.3.3 of Recommendation\ G.704, i.e. for a CRC check bit procedure. .RT .sp 1P .LP 2.2 \fIUse of derived channel time slots\fR .sp 9p .RT .PP Time slots not accessed flow transparently through the equipment. .PP \fINote\fR \ \(em\ Further study is required as to whether the binary content of time slots used at the access points should be replaced, after extraction from the composite signal, by the AIS. .RT .sp 1P .LP 2.2.1 \fI64 kbit/s access\fR .sp 9p .RT .PP The number of accessible channel time slots should be at least four and the equipment shall allow access to any of channel time slots\ 1 to\ 15 and\ 17 to\ 31. .PP \fINote\fR \ \(em\ Equipment exists which provides access to at least four channel time slots in the following order of priority: 6 \(em 22 \(em 14 \(em 30 \(em 2 \(em 18 \(em 10 \(em 26 \(em 4 \(em 20 \(em 12 \(em 28 \(em 8 \(em 24 \(em 5 \(em 21 \(em 13 \(em 29\ \(em 1 \(em 17 \(em 9 \(em 25 \(em 3 \(em 19 \(em 11 \(em 27 \(em 7 \(em 23 \(em 15 \(em 31. .bp .RT .LP .rs .sp 31P .ad r \fBFigure 1/G.739, p. \fR .sp 1P .RT .ad b .RT .sp 1P .LP 2.2.2 \fI320 kbit/s access\fR .sp 9p .RT .PP The time slot allocation for digital channels with bit rate at 320\ kbit/s is given in Table\ 1/G.739. .RT .ce \fBH.T. [T1.739]\fR .ce TABLE\ 1/G.739 .ps 9 .vs 11 .nr VS 11 .nr PS 9 .TS center box; cw(34p) sw(34p) sw(28p) sw(34p) sw(34p) sw(28p) | cw(36p) , c | c | c | c | c | c | ^ . 320 kbit/s channels (Note 1) { Digital sound\(hyprogramme access points } A B C D E F _ .T& lw(34p) | lw(34p) | cw(28p) | cw(34p) | cw(34p) | cw(28p) | cw(36p) . { 1 \(hy 2 \(hy 3 \(hy 4 \(hy 5 } { 6 \(hy 7 \(hy 8 \(hy 9 \(hy 10 } { 11 \(hy 12 \(hy 13 \(hy 14 \(hy 15 } { 17 \(hy 18 \(hy 19 \(hy 20 \(hy 21 } { 22 \(hy 23 \(hy 24 \(hy 25 \(hy 26 } { 27 \(hy 28 \(hy 29 \(hy 30 \(hy 31 } { I3, T, E3 Figure\ 1b/G.738 } .TE .LP \fINote\ 1\fR \ \(em\ The six possible 320 kbit/s channels in a 2048\ kbit/s stream are numbered A to F. Preferably the channel pairs A\(hyB, C\(hyD and E\(hyF should be used for stereophonic transmission. .LP \fINote\ 2\fR \ \(em\ If the channel time slot 16 which is assigned to signalling as covered in \(sc\ 5 is not needed for signalling, it may be used for purposes other than a voice channel encoded within the PCM multiplex equipment. .nr PS 9 .RT .ad r \fBTable 1/G.739 [T1.739], p. \fR .sp 1P .RT .ad b .RT .LP .bp .sp 2P .LP \fB3\fR \fBFrame alignment and CRC procedures both at insertion (I\fR\(da\fB0) and extraction (E\fR\(da\fB1) sides\fR .sp 1P .RT .PP An illustration of the procedure is given in Figure\ 2/G.706. .RT .sp 1P .LP 3.1 \fILoss of frame alignment\fR .sp 9p .RT .PP Refer to \(sc\ 4.1.1 of Recommendation\ G.706. .RT .sp 1P .LP 3.2 \fIRecovery of frame alignment\fR .sp 9p .RT .PP Refer to \(sc\ 4.1.2 of Recommendation\ G.706. .RT .sp 1P .LP 3.3 \fICRC multiframe alignment in TSO\fR .sp 9p .RT .PP Refer to \(sc\ 4.2 of Recommendation\ G.706. .RT .sp 1P .LP 3.4 \fICRC bit monitoring\fR .sp 9p .RT .PP Refer to \(sc\ 4.3 of Recommendation\ G.706. .RT .sp 2P .LP \fB4\fR \fBFault conditions and consequent actions\fR .sp 1P .RT .sp 1P .LP 4.1 \fIFault conditions\fR .sp 9p .RT .PP The equipment should detect the following conditions: .RT .PP 4.1.1 Failure of power supply. .sp 9p .RT .PP 4.1.2 Loss of incoming signal at I\d2\uor \d3\u. .sp 9p .RT .PP \fINote\fR \ \(em\ This detection is not mandatory when contradirectional interfaces are used. .PP 4.1.3 Loss of the incoming signal at 2048\ kbit/s both at insertion (I\d0\u) and extraction (E\d1\u) sides. .sp 9p .RT .PP \fINote\ 1\fR \ \(em\ The detection of this fault condition is required only when it does not result in an indication of loss of frame alignment. .PP \fINote\ 2\fR \ \(em\ Where separate circuits are used for the digital signal and the timing signal, the loss of either or both should constitute loss of the incoming signal. .RT .PP 4.1.4 Loss of frame alignment both at insertion (I\d0\u) and extraction (E\d1\u) sides. .sp 9p .RT .PP 4.1.5 Excessive bit error ratio detected by monitoring the frame alignment signal at both the insertion (I\d0\u) and extraction (E\d1\u) sides. .sp 9p .RT .PP \fINote\fR \ \(em\ The detection of this fault condition at insertion side (I\d0\u) depends on the type of application of this equipment in a network and therefore is not mandatory. .PP 4.1.5.1 With a random bit error ratio of \(=\ 10\uD\dlF261\u4\d, the probability of activating the indication of fault condition within a few seconds should be less than 10\uD\dlF261\u6\d. .sp 9p .RT .PP With a random bit error ratio of \(>="\ 10\uD\dlF261\u3\d, the probability of activating the indication of fault condition within a few seconds should be higher than\ 0.95. .PP 4.1.5.2 With a random bit error ratio of \(>="\ 10\uD\dlF261\u3\d, the probability of deactivating the indication of fault condition within a few seconds should be almost\ 0. .sp 9p .RT .PP With a random bit error ratio of \(=\ 10\uD\dlF261\u4\d, the probability of deactivating the indication of fault condition within a few seconds should be higher than\ 0.95. .PP \fINote\fR \ \(em\ The activating and deactivating period specified as \*Qa few seconds\*U is intended to be in the order of\ 4 to\ 5 seconds. .bp .RT .sp 1P .LP 4.2 \fIConsequent actions\fR .sp 9p .RT .PP Further to the detection of fault condition, appropriate actions should be taken as specified in Table\ 2/G.739. The consequent actions are as follows: .RT .PP 4.2.1 Prompt maintenance alarm indication generated to signify that performance is below acceptable standards and maintenance attention is required locally. When the AIS at the 2048\ kbit/s inputs (I\d0\u, E\d1\u) is detected (see General Notes below to\ \(sc\ 4.2), the prompt maintenance alarm indication associated with loss of frame alignment (see \(sc\ 4.1.4) and excessive error rate (see \(sc\ 4.1.5) should be inhibited, while the rest of the consequent actions are in accordance with those associated in Table\ 2/G.739 with the two fault conditions. .sp 9p .RT .PP \fINote\fR \ \(em\ The location and provision of any visual and/or audible alarm activated by the alarm indications given in\ \(sc\ 4.2.1 is left to the discretion of each Administration. .PP 4.2.2 AIS applied to E\d2\u, E\d3\uoutputs (see General Notes below to\ \(sc\ 4.2). This action should be taken as soon as possible and not later than\ 2\ ms after the detection of the fault condition. .sp 9p .RT .PP 4.2.3 AIS applied to relevant time slots in the composite 2048\ kbit/s output signal at insertion side (I\d1\u) if supervision of the incoming I\d2\uand I\d3\usignal is provided. .sp 9p .RT .PP 4.2.4 Inhibition of I\d2\uor \d3\udigital information insertion. .sp 9p .RT .PP 4.2.5 Both 2048 kbit/s signals are bypassed. .sp 9p .RT .PP \fINote\fR \ \(em\ The provision of this consequent action depends on the type of application of this equipment in a network and therefore is not mandatory. .PP 4.2.6 AIS applied to the 2048 kbit/s output, extraction side (E\d0\u). .sp 9p .RT .PP \fINote\fR \ \(em\ The provision of this consequent action depends on the type of application of this equipment in a network and therefore is not mandatory. .PP 4.2.7 AIS applied to the 2048\ kbit/s output, insertion side (I\d1\u). .sp 9p .RT .PP \fINote\fR \ \(em\ The provision of this consequent action depends on the type of this equipment in a network and therefore is not mandatory. .sp 1P .LP \fIGeneral Notes to \(sc 4.2\fR .sp 9p .RT .PP \fINote\ 1\fR \ \(em\ The equivalent binary content of the alarm indication signal (AIS) is a continuous stream of binary\ 1s. The strategy for detecting the presence of the AIS should be such that with a high probability the AIS is detectable even in the presence of random errors having a mean error ratio 1\(mu10\uD\dlF261\u3\d. Nevertheless, a signal in which all the binary elements, with the exception of the frame alignment signal, are in the state\ 1, should not be taken as an AIS. .PP \fINote\ 2\fR \ \(em\ All timing requirements quoted apply equally to restoration, subsequent to the fault condition clearing. .RT .sp 2P .LP \fB5\fR \fBInterfaces\fR .sp 1P .RT .PP The digital interfaces at 2048 kbit/s should be in accordance with Recommendation\ G.703. .PP The digital interfaces at 64\ kbit/s should be either of the codirectional or the contradirectional type specified in Recommendation\ G.703. .PP The need to define a digital interface operating at 320\ kbit/s is under study. .PP \fINote\ 1\fR \ \(em\ It should be noted that according to the principle of minimizing the number of different types of interfaces, the information rate of 320\ kbit/s will be offered to customers at the user/network interface level using the 2048\ kbit/s interface as defined in Recommendations\ I.431 and\ G.703. .PP \fINote\ 2\fR \ \(em\ In the case of the 64 kbit/s codirectional interface, the design of the input ports should take into account the need to provide octet alignment, to allow controlled slips when the tributary timing and that of the multiplexer timing source are plesiochronous, and to absorb jitter and wander up to the limits given in Recommendation\ G.823. .bp .RT .ce \fBH.T. [T2.739]\fR .ps 9 .vs 11 .nr VS 11 .nr PS 9 .TS center box; cw(342p) . TABLE\ 2/G.739 .T& cw(342p) . { \fBFault conditions and consequent actions for the external access equipment\fR } .TE .TS center box; cw(60p) | cw(36p) sw(36p) sw(36p) sw(48p) | cw(42p) | cw(42p) | cw(42p) , ^ | c | c | c | c | ^ | ^ | ^ . { Fault conditions (see \(sc\ 4.1) } { Consequent actions (see \(sc\ 4.2) } { Both 2048 kbit/s signals are bypassed (see Note under \(sc\ 4.2.5) } { AIS applied to the 2048\ kbit/s output, extraction side (E 0) (see Note under \(sc\ 4.2.6) } { AIS applied to the 2048\ kbit/s output, insertion side (I 1) (see Note under \(sc\ 4.2.7) } { Prompt maintenance alarms indication generated } { AIS applied to E 2 or E 3 outputs } { Inhibition of digital information insertion I 2, I 3 } { AIS applied to the relevant time slot of the 2048\ kbit/s composite signal at insertion side (I 0) } _ .T& cw(60p) | cw(36p) | lw(36p) | lw(36p) | lw(48p) | cw(42p) | cw(42p) | cw(42p) . Failure of power supply Yes Yes Yes (if practicable) Yes (if practicable) _ .T& cw(60p) | cw(36p) | lw(36p) | lw(36p) | cw(48p) | cw(42p) | cw(42p) | cw(42p) . { Loss of incoming signal at I 2 or I 3 inputs (see Note under \(sc\ 4.1.2) } Yes Yes _ .T& cw(30p) | cw(30p) | cw(36p) | cw(36p) | cw(36p) | cw(48p) | cw(42p) | cw(42p) | cw(42p) , ^ | l | l | l | l | l | l | l | l. { Loss of incoming signal at 2048\ kbit/s } Extr.s. (E 1) Yes Yes Yes Ins.s. (I 0) Yes Yes Yes _ .T& cw(30p) | cw(30p) | cw(36p) | cw(36p) | cw(36p) | cw(48p) | cw(42p) | cw(42p) | cw(42p) , ^ | l | l | l | l | l | l | l | l. { Loss of frame alignment (see Note 2 of Rec.\ G.706, \(sc\ 4.2) } Extr.s. (E 1) Yes (see \(sc\ 4.2.1) Yes Yes Ins.s. (I 0) Yes (see \(sc\ 4.2.1) Yes Yes _ .T& cw(30p) | cw(30p) | cw(36p) | cw(36p) | cw(36p) | cw(48p) | cw(42p) | cw(42p) | cw(42p) , ^ | l | l | l | l | l | l | l | l. { Error ratio 1 | (mu | 0\uD\dlF261\u3\d on the frame alignment signal (see Note under \(sc\ 4.1.5) } Extr.s. (E 1) Yes (see \(sc\ 4.2.1) Yes Yes Ins.s. (I 0) Yes (see \(sc\ 4.2.1) Yes Yes .TE .LP \fINote\fR \ \(em\ A \fIYes\fR | in the table signifies that an action should be taken as a consequence of the relevant fault condition. An \fIopen space\fR in the table signifies that the relevant action should not be taken as a consequence of the relevant fault condition, if this condition is the only one present. If more than one fault condition is simultaneously present, the relevant action should be taken if, for at least one of the conditions, a \fIYes\fR is defined in relation to this action. .nr PS 9 .RT .ad r \fBTable 2/G.739 [T2.739], p. \fR .sp 1P .RT .ad b .RT .LP .bp .sp 2P .LP \fB6\fR \fBJitter\fR .sp 1P .RT .sp 1P .LP 6.1 \fIJitter at 2048 kbit/s output\fR .sp 9p .RT .PP When there is no jitter on the 2048\ kbit/s inputs (I\d0\u, E\d1\u) the peak\(hyto\(hypeak jitter at the 2048\ kbit/s outputs (I\d1\u, E\d0\u) should not exceed 0.10\ UI when it is measured within the frequency range from \fIf\fR\d1\u\ =\ 20\ Hz to \fIf\fR\d4\u\ =100\ kHz. The equivalent binary content of the test signal applied at the 2048\ kbit/s input shall be a pseudo\(hyrandom bit sequence of length 2\u1\d\u5\d\(em1 as specified in Recommendation\ 0.151. See Figure\ 2/G.823. .PP \fINote\fR \ \(em\ It may be necessary to include a frame alignment signal in the test signal to enable the measurement to be carried out. .RT .sp 2P .LP 6.2 \fIJitter at E\fI .sp 1P .RT .EF '% \fI2\ and\'' .OF '''\fI2\ and\ %' .EF '% \fI3\ outputs'' .OF '''\fI3\ outputs %' .PP 6.2.1 The jitter at the E\d2\u(64\ kbit/s) output when there is no jitter at the 2048\ kbit/s input (E\d1\u) should not exceed 0.025\ UI when measured within the frequency range from \fIf\fR\d1\u\ =\ 20\ Hz to \fIf\fR\d4\u\ =\ 100\ kHz. The equivalent binary content of the test signal applied at the 2048\ kbit/s input shall be a pseudo\(hyrandom bit sequence of length 2\u1\d\u5\d\(em1 as specified in Recommendation\ O.151. .sp 9p .RT .PP \fINote\fR \ \(em\ In order to carry out this measurement without invoking AIS at the 64\ kbit/s output, it will normally be necessary to include a frame alignment signal in the test signal. .PP 6.2.2 Since the physical and electrical characteristics of a 320\ kbit/s interface are identical to those of the 2048\ kbit/s interface, the jitter at the E\d3\u(synchronous 320\ kbit/s) output when there is no jitter at the 2048\ kbit/s input (E\d1\u) is according to \(sc\ 6.1 above. .sp 9p .RT .sp 2P .LP 6.3 \fIJitter transfer functions\fR .sp 1P .RT .PP 6.3.1 The jitter transfer function between the 2048\ kbit/s input (I\d0\u, \d1\u) and the output (I\d1\u, E\d0\u) should not exceed the gain/frequency limits given in Figure\ 2/G.739. .sp 9p .RT .PP Some Administrations require that equipment be fitted with jitter reducers . In this case, the jitter transfer function should not exceed the gain/frequency limits given in Figure\ 3/G.739. .PP \fINote\ 1\fR \ \(em\ The 2048 kHz signal shall be modulated with sinusoidal jitter. The equivalent binary content of the test signal shall be 1000. .PP \fINote\ 2\fR \ \(em\ It may be necessary to include a frame alignment signal in the test signal to enable the measurement to be carried out. .RT .PP 6.3.2 The jitter transfer function between the 2048\ kbit/s input (E\d1\u) and the E\d2\u(64\ kbit/s) output should not exceed \(em29.6\ dB when measured over the frequency range \fIf\fR\d0\uto 10\ kHz. The frequency \fIf\fR\d0\ushould be less than 20\ Hz and as low as possible (e.g. 10\ Hz), taking into account the limitations of measuring equipment. .sp 9p .RT .PP \fINote\ 1\fR \ \(em\ The 2048\ kbit/s test signal shall be modulated by sinusoidal jitter. The equivalent binary content of the test signal shall be\ 1000. .PP \fINote\ 2\fR \ \(em\ In order to carry out this measurement without invoking AIS at the 64\ kbit/s output, it will normally be necessary to include a frame alignment signal in the test signal. .PP \fINote\ 3\fR \ \(em\ The jitter reduction of 1/32 due to demultiplexing is equivalent to \(em30.1\ dB. .RT .PP 6.3.3 Since the physical and electrical characteristics of a\ 320\ kbit/s interface are identical to those of the 2048\ kbit/s interface, the jitter transfer function between the 2048\ kbit/s input (E\d1\u) and E\d3\u(synchronous 320\ kbit/s) output is according to \(sc\ 6.3.1 above. .sp 9p .RT .LP .rs .sp 4P .ad r Blanc .ad b .RT .LP .bp .LP .rs .sp 25P .ad r \fBFigure 2/G.739, p. \fR .sp 1P .RT .ad b .RT .LP .rs .sp 23P .ad r \fBFigure 3/G.739, p. \fR .sp 1P .RT .ad b .RT .LP .bp