.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'
.IP
\fB7.6\fR 	\fBPrincipal characteristics of\fR 
\fBtranscoder and digital circuit\fR \fBmultiplication equipments\fR 
.sp 1P
.RT
.sp 2P
.LP
\fBRecommendation\ G.761\fR 
.RT
.sp 2P
.ce 1000
\fBGENERAL\ \fR \fBCHARACTERISTICS\ OF\ A\ 60\(hyCHANNEL\fR 
.EF '%	Fascicle\ III.4\ \(em\ Rec.\ G.761''
.OF '''Fascicle\ III.4\ \(em\ Rec.\ G.761	%'
.ce 0
.sp 1P
.ce 1000
\fBTRANSCODER\ EQUIPMENT\fR 
.ce 0
.sp 1P
.ce 1000
\fI(Malaga\(hyTorremolinos, 1984; amended at Melbourne, 1988)\fR 
.sp 9p
.RT
.ce 0
.sp 1P
.LP
\fB1\fR 	\fBGeneral\fR 
.sp 1P
.RT
.PP
The 60\(hychannel transcoder implements a conversion between two
30\(hychannel 2048\ kbit/s PCM streams and one 60\(hychannel 2048\ kbit/s 
ADPCM stream. In the 30\(hychannel 2048\ kbit/s streams, the telephone 
signals are coded using 
64\ kbit/s A\(hylaw PCM as specified in Recommendation\ G.711. In the 60\(hychannel 
2048\ kbit/s stream, the telephone signals are coded using 32\ kbit/s ADPCM 
as specified in Recommendation\ G.721. Figure\ 1/G.761 indicates the nomenclature 
used for the three different signal ports\ A, B and\ C.
.PP
\fINote\ 1\fR \ \(em\ Administrations should take into account the guidance 
given in Recommendation\ G.721 concerning the use and transmission performance 
of 
32\ kbit/s ADPCM .
.PP
\fINote\ 2\fR \ \(em\ It should be noted that the transcoder equipment 
described in this Recommendation has a limited capability of transparently 
transmitting 64\ kbit/s data channels and this should be taken into account 
in the planning of networks which are likely to evolve into an ISDN (see 
\(sc\ 3.8). 
.PP
This Recommendation is divided into two parts:
.RT
.LP
	\(em
	 \(sc 2 contains the interface requirements associated with the port\ 
C. These requirements are not only applicable to the 60\(hychannel transcoder 
equipment, but could be applied, in the future, to other equipment such 
as a 
60\(hychannel multiplex terminal, a 60\(hychannel terminating unit at a 
TDM switch, or a TDMA terminal. In these latter cases, the\ A and\ B interfaces 
would be 
virtual. As well as point\(hyto\(hypoint operation, account has been taken of
multi\(hydestination operation in TDMA applications.
.LP
	\(em
	\(sc 3 contains the requirements which are specific to a
60\(hychannel transcoder equipment realization.
.LP
.rs
.sp 13P
.ad r
\fBFigure 1/G.761, p.\fR 
.sp 1P
.RT
.ad b
.RT
.sp 2P
.LP
\fB2\fR \fBCharacteristics of a 2048 kbit/s signal organized in 64 kbit/s 
and/or 32 kbit/s time slots\fR \fB(port C)\fR 
.sp 1P
.RT
.sp 1P
.LP
2.1
	\fIInterface C\fR 
.sp 9p
.RT
.PP
The electrical characteristics of the 2048 kbit/s interface are in accordance 
with Recommendation\ G.703, \(sc\ 6. 
.bp
.RT
.sp 1P
.LP
2.2
	\fIFrame structure\fR 
.sp 9p
.RT
.PP
The frame structure is in accordance with Recommendation G.704,
\(sc\ 2.3, with bit\ 1 of time slot\ 0 used for the cyclic redundancy check 
(CRC) 
procedure.
.PP
Time slots 1 to 15 and 17 to 31 each corresponds to:
.RT
.LP
	\(em
	either two 4\(hybit samples of telephone signals coded using
32\ kbit/s ADPCM originating from the same incoming PCM stream (A or\ B); 
the bit ordering of the 32 kbit/s signals is such that the 4\(hybit words 
are transmitted in bit order starting with bit\ 1 (see \(sc\(sc\ 4.2.2 
and\ 4.2.3 of 
Recommendation\ G.721). Bits\ 1 to\ 4 correspond to the first 32\ kbit/s 
signal and bits\ 5 to\ 8 correspond to the second 32\ kbit/s signal; 
.LP
	\(em
	or a digital signal at 64 kbit/s.
.PP
Where stream C is transmitting 60 telephone signals, the numbering of the 
channels and the correspondence between the 64\ kbit/s PCM channels in 
streams\ A and\ B and the 32\ kbit/s ADPCM channels in stream\ C are given in
Table\ 1/G.761.
.LP
.sp 2
.ce
\fBH.T. [T1.761]\fR 
.ce
TABLE\ 1/G.761
.ce
\fBOrganization of 2048 kbit/s frame for 60\(hychannels
.ce
\fBat 32 kbit/s (stream C)\fR 
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
lw(36p) | cw(21p) | cw(11p) | cw(11p) | cw(11p) | cw(17p) | cw(11p) | cw(11p) | cw(11p) | cw(11p) | cw(11p) | cw(11p) | cw(11p) | cw(11p) | cw(11p) | cw(11p) | cw(11p) .
8\(hybit time slot number	0	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15
_
.T&
lw(36p) | cw(21p) | cw(11p) | cw(11p) | cw(11p) | cw(17p) | cw(11p) | cw(11p) | cw(11p) | cw(11p) | cw(11p) | cw(11p) | cw(11p) | cw(11p) | cw(11p) | cw(11p) | cw(11p) .
Bits 1\(hy4 of channel	\(em	1A	1B	3A	3B	5A	5B	7A	7B	9A	9B	11A	11B	13A	13B	15A
_
.T&
lw(36p) | cw(21p) | cw(11p) | cw(11p) | cw(11p) | cw(17p) | cw(11p) | cw(11p) | cw(11p) | cw(11p) | cw(11p) | cw(11p) | cw(11p) | cw(11p) | cw(11p) | cw(11p) | cw(11p) .
Bits 5\(hy8 of channel	\(em	2A	2B	4A	4B	6A	6B	8A	8B	10A	10B	12A	12B	14A	14B	16A
_
.TE
.nr PS 9
.RT
.ad r
\fBTable 1/G.761 [T1.761], p.\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.rs
.sp 1P
.ad r
Blanc
.ad b
.RT
.LP
.bp
.sp 1P
.LP
2.3
	\fIAllocation of bits in time slot 0\fR 
.sp 9p
.RT
.PP
The allocation of the bits in time slot 0 is given in
Recommendation\ G.704, \(sc\ 2.3, with bit\ 1 of time slot\ 0 used for 
the cyclic 
redundancy check procedure.
.PP
Bits 3 to 8 in TS0 of those frames not containing the frame alignment signal 
are used to transmit: 
.RT
.LP
	\(em
	alarm indications associated with PCM streams A or B (see
\(sc\(sc\ 2.6.2 and\ 2.6.3 dealing with alarm indications);
.LP
	\(em
	spare bits associated with PCM streams A or B (see
\(sc\ 3.3).
.sp 1P
.LP
2.4
	\fIFrame alignment and CRC procedures\fR 
.sp 9p
.RT
.PP
The strategy for loss and recovery of frame alignment and CRC
multiframe alignment is given in Recommendation\ G.706, \(sc\ 4.
.RT
.sp 1P
.LP
2.5
	\fIAllocation of bits in TS16\fR 
.sp 9p
.RT
.PP
TS16 can be used:
.RT
.LP
	\(em
	either for signalling purposes; namely channel associated
signalling (see \(sc\ 2.5.1) and common channel signalling (see \(sc\ 2.5.2);
.LP
	\(em
	or, as envisaged in \(sc 5.1 of Recommendation G.704, for the
transmission of telephone signals; in this case two samples of telephone
signals each coded with 4\ bits. Used in this way, stream\ C can transmit 
up to 62\ telephone signals. Bits\ 1 to\ 4 and\ 5 to\ 8 of stream\ C will 
correspond to 
64\ kbit/s PCM signals transmitted in TS16 of PCM streams\ A and\ B
respectively.
.sp 1P
.LP
2.5.1
	\fIChannel associated signalling\fR 
.sp 9p
.RT
.PP
The allocation of bits in TS16 will depend on the number of
signalling bits per channel.
.RT
.sp 1P
.LP
2.5.1.1
	\fITwo or less signalling bits per channel\fR 
.sp 9p
.RT
.PP
This applies to the digital version of Signalling System R2 (see
Recommendation\ Q.421) specified for international applications. This also
applies to a number of national signalling systems.
.PP
TS16 is organized in multiframes. Each multiframe contains 16
consecutive frames, numbered from\ 0 to\ 15. The multiframe repetition 
frequency is 500\ Hz. 
.RT
.sp 1P
.LP
2.5.1.1.1
	\fIAllocation of bits in TS16 frame 0\fR 
.sp 9p
.RT
.PP
Table 2/G.761 indicates the content of TS16 frame 0.
.PP
Bits 1 to 4 are fixed at 0 and constitute the multiframe alignment
signal.
.PP
Bits 5 and 8 are used to indicate \*QAIS in TS16\*U of PCM streams A and\ 
B (see \(sc\ 2.6.5). 
.PP
Bits 6 and 7 are used to transmit the remote alarm indications
associated with the multiframe of PCM streams\ A and\ B (see \(sc\ 2.6.6).
.RT
.ce
\fBH.T. [T2.761]\fR 
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(96p) .
TABLE\ 2/G.761
.T&
cw(96p) .
 {
\fBContent of TS16 frame 0\fR
 }
.T&
cw(96p) .
Bit number
.TE
.TS
center box ;
cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) .
1	2	3	4	5	6	7	8
_
0	0	0	0	X 5	X 6	X 7	X 8
_
.TE
.nr PS 9
.RT
.ad r
\fBTable 2/G.761 [T2.761], p.\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.sp 1P
.LP
2.5.1.1.2
	\fIAllocation of bits in TS16 frames 1 to 15\fR 
.sp 9p
.RT
.PP
Table 3/G.761 indicates the content of TS16 in frames 1 to 15.
.PP
This allocation of bits provides each 32 kbit/s channel with two
signalling channels at 500\ bit/s nominated \*Qa\*U and \*Qb\*U as defined in
Recommendation\ G.704, \(sc\ 5.1.3.2.2.
.PP
To minimize the risks of simulation of the multiframe alignment
signal, special processing of certain signalling bits is carried out as
described in \(sc\ 2.5.1.1.3.
.PP
In the case of direct transfer of some 64 kbit/s time slots of PCM
streams\ A or\ B, the four bits of TS16 associated with the transferred time
slots will be transparently transmitted and allocated in accordance with
Table\ 7/G.704. They will not be subject to the special processing described 
in \(sc\ 2.5.1.1.3. The four bits of time slot\ 16 associated with each 
of the time 
slots not used in PCM streams\ A and\ B because of the direct transfer will be
restituted by the transcoder with the following values:
.PP
a = 0; b = 1; and d = 1, in conformity with Table 9/G.704.
.PP
The signalling distortion of any signalling channel will not be
greater than \(+- | \ ms.
.RT
.ce
\fBH.T. [T3.761]\fR 
.ce
TABLE\ 3/G.761
.ce
\fBContent of TS16 frames 1 to 15\fR 
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(66p) | lw(24p) | lw(24p) | lw(24p) | lw(24p) .
Time slot 16 bit number	1 2	3 4	5 6	7 8
_
.T&
cw(66p) | lw(24p) | lw(24p) | lw(24p) | lw(24p) .
Signalling	Channel a b	Channel a b	Channel a b	Channel a b
_
.T&
lw(66p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) .
Frame 1	\ 1A	\ 2A	15B	16B
_
.T&
lw(66p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) .
Frame 2	\ 1B	\ 2B	17A	18A
_
.T&
lw(66p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) .
Frame 3	\ 3A	\ 4A	17B	18B
_
.T&
lw(66p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) .
Frame 4	\ 3B	\ 4B	19A	20A
_
.T&
lw(66p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) .
Frame 5	\ 5A	\ 6A	19B	20B
_
.T&
lw(66p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) .
Frame 6	\ 5B	\ 6B	21A	22A
_
.T&
lw(66p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) .
Frame 7	\ 7A	\ 8A	21B	22B
_
.T&
lw(66p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) .
Frame 8	\ 7B	\ 8B	23A	24A
_
.T&
lw(66p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) .
Frame 9	\ 9A	10A	23B	24B
_
.T&
lw(66p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) .
Frame 10	\ 9B	10B	25A	26A
_
.T&
lw(66p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) .
Frame 11	11A	12A	25B	26B
_
.T&
lw(66p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) .
Frame 12	11B	12B	27A	28A
_
.T&
lw(66p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) .
Frame 13	13A	14A	27B	28B
_
.T&
lw(66p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) .
Frame 14	13B	14B	29A	30A
_
.T&
lw(66p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) .
Frame 15	15A	16A	29B	30B
.TE
.LP
\fINote\fR
\ \(em\ The organization of the multiframe ensures consistency with the frame and multiframe organization of Recommendation\ G.704, \(sc\ 5.1.3 and allows the
possibility of the mixed use in stream\ C of 32\ kbit/s and 64\ kbit/s channels
with their associated signalling.
.nr PS 9
.RT
.ad r
\fBTable 3/G.761 [T3.761], p.\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.sp 1P
.LP
2.5.1.1.3
	\fISpecial processing of signalling bits\fR 
.sp 9p
.RT
.PP
The signalling bits to be transmitted in bit 2 (respectively 4, 6 and\ 
8) of TS16 (frames\ 1 to\ 15) are calculated from B\fI\fI\d\fIn\fR\\d\\u(em\d1\u, 
B\fI\fI\d\fIn\fR\\d\\u(em\d2\u, B\fI\fI\d\fIn\fR\\d\\u(em\d3\u, b\fI\fI\d\fIn\fR\\d\\u(em\d1\uand 
b\fI\fI\d\fIn\fR\uin 
accordance with Table\ 4/G.761 where:
.RT
.LP
	i)
	b\fI\fI\d\fIn\fR\uis the signalling bit before processing;
.LP
	ii)
	B\fI\fI\d\fIn\fR\uis the signalling bit after processing, and
.LP
	iii)
	the subscripts \fIn\fR \(em3, \fIn\fR \(em2, and \fIn\fR \(em1 relate to
previous signalling bits pertaining to the same telephone channel; more
specifically, if\ b\fI\fI\d\fIn\fR\uis a bit with a given number (2, 4, 
6 or\ 8) in any 
time slot\ 16 of frames 1\ to\ 15, then\ b\d\fIn\fR\\d\\u(em\d1\uis the 
bit with the same number, one multiframe earlier. 
.PP
\fINote\ 1\fR \ \(em\ It follows from the above that there are 60 individual 
and independent processing operations at the same time. 
.PP
The reverse processing (after transmission) is in accordance with
Table 5/G.761. The reverse processed value \*^b\fI\fI\d\fIn\fR\uis deduced 
from the 
successive received bits B\fI\fI\d\fIn\fR\\d\\u(em\d3\u, B\fI\fI\d\fIn\fR\\d\\u(em\d2\u, 
B\fI\fI\d\fIn\fR\\d\\u(em\d1\u, 
B\fI\fI\d\fIn\fR\uand from the previous value \*^b\fI\fI\d\fIn\fR\\d\\u(em\d1\u. 
In the absence of 
transmission errors in stream\ C, \*^b\fI\fI\d\fIn\fR\u\ =\ b\fI\fI\d\fIn\fR\uand 
there is no increase in signalling distortion. When this is not so, the 
error multiplication factor 
lies between\ 2 and\ 4.
.PP
When, in the case of fault conditions on multiframe A or B (see
Table\ 9/G.761), the signalling bits need to be forced to state\ 1, this 
should be implemented on the unprocessed signalling channels (i.e.\ before 
the special processing at the send end or after the reverse processing 
at the receive 
end). This does not apply to the cases of \*Qpartial AIS stream A\ (B)\*U 
considered in \(sc\ 2.6.2 where the AIS is all\ 1s, unprocessed. 
.RT
.sp 1P
.LP
2.5.1.1.4
	\fILoss and recovery of multiframe alignment\fR 
.sp 9p
.RT
.PP
The multiframe alignment should be assumed to have been lost when two consecutive 
multiframe alignment signals have been received in error. 
.PP
The multiframe alignment should be assumed to have been recovered
following detection of an all\(hyzero 4\(hybit word formed by the first 
four bits of a time slot 16 and an all\(hyzero 4\(hybit word one multiframe 
period later. 
.RT
.sp 1P
.LP
2.5.1.2
	\fIMore than two signalling bits per channel\fR 
.sp 9p
.RT
.PP
See \(sc 3.8.
.RT
.sp 1P
.LP
2.5.2
	\fICommon channel signalling\fR 
.sp 9p
.RT
.PP
TS16 of stream C can be used for common channel signalling. In this case, 
its content corresponds, without any modification, to that of TS16 of 
either PCM stream\ A or PCM stream\ B. It should be noted that the simultaneous 
transfer of TS16 from both streams\ A and\ B is not envisaged in this case. 
.PP
Time slot 16 of PCM stream B (or A) not used because of the direct
transfer of time slot\ 16 of PCM stream\ A (or\ B) in time slot\ 16 of the PCM
stream\ C will be restituted by the transcoder in the form of an all\(hy0s 
signal or an all\(hy1s signal. 
.RT
.sp 1P
.LP
2.6
	\fIAlarm indications\fR 
.sp 9p
.RT
.PP
The following alarm indications can be transmitted in
stream\ C.
.RT
.sp 1P
.LP
2.6.1
	\fIAIS stream C\fR 
.sp 9p
.RT
.PP
This means that a fault, common to the 60 channel has been detected in 
the send side \*QAIS stream\ C\*U is transmitted as an all ones configuration 
in stream\ C. 
.RT
.sp 1P
.LP
2.6.2
	\fIAIS stream A (respectively B)\fR 
.sp 9p
.RT
.PP
This means that a fault, common to the 30 channels of stream A
(respectively\ B), has been detected in the send side.
.PP
For the send side, the following applies:
.PP
When \*QAIS stream A\*U and \*QAIS stream B\*U are present simultaneously,
then \*QAIS stream\ C\*U should be transmitted.
.bp
.PP
When \*QAIS stream A\*U (respectively B) is present, but not \*QAIS
stream\ B\*U (respectively\ A), then the informaiton bits and the signalling 
bits associated with stream\ B (respectively\ A) should be transmitted 
normally and an all ones configuration should be transmitted in the time 
slots associated with stream\ A (respectively\ B) in stream\ C and the 
corresponding bits in TS16. In 
addition, bit\ 7 (respectively\ 8) of TS0 not containing the frame alignment
signal in stream\ C should be set to\ 1 to indicate the \*QAIS stream\ A\*U
(respectively\ B) (see 
Table\ 6/G.761). This configuration in stream\ C is
nominated \*Qpartial AIS stream\ A\*U (respectively \*Qpartial AIS stream\ 
B\*U). 
.PP
For the receive side, the following applies:
.PP
Partial AIS stream A (respectively B) will be considered as being
present if bit\ 7 (respectively bit\ 8) is detected at state\ 1 on three
consecutive occasions.
.PP
Partial AIS stream A (respectively B) will be considered as having
ceased if bit\ 7 (respectively\ 8) is detected at state\ 0 on three consecutive
occasions.
.RT
.LP
.rs
.sp 26P
.ad r
\fBCuadro 4/G.761 [T4.761], p.
.sp 1P
.RT
.ad b
.RT
.LP
.rs
.sp 11P
.ad r
Blanc
.ad b
.RT
.LP
.bp
.ce
\fBH.T. [T5.761]\fR 
.ce
TABLE\ 5/G.761
.ce
\fBProcessing of signalling bits (receive side)\fR 
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(30p) | cw(120p) | cw(30p) .
Input	State	Output
_
.TE
.TS
center box;
cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) .
B\fI\fI	B\fI\fI \(em 3	B\fI\fI \(em 2	B\fI\fI \(em 1	\*^b\fI\fI \(em 1	\*^b\fI\fI
_
.T&
cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) .
0	0	0	0	0	1
.T&
cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) .
0	0	0	0	1	0
.T&
cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) .
1	0	0	0	0	0
.T&
cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) .
1	0	0	0	1	1
.T&
cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) .
0	0	0	1	0 or 1	0
.T&
cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) .
1	0	0	1	0 or 1	1
.T&
cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) .
0	0	1	0	0 or 1	1
.T&
cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) .
1	0	1	0	0 or 1	0
.T&
cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) .
0	0	1	1	0 or 1	0
.T&
cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) .
1	0	1	1	0 or 1	1
.T&
cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) .
0	1	0	0	1	0
.T&
cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) .
1	1	0	0	1	1
.T&
cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) .
0	1	0	1	0	1
.T&
cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) .
1	1	0	1	0	0
.T&
cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) .
0	1	1	0	0	1
.T&
cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) .
1	1	1	0	0	0
.T&
cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) .
0	1	1	1	1	0
.T&
cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) .
1	1	1	1	1	1
.TE
.LP
\fINote\fR
\ \(em\ Other states may be possible, just after powering\(hyon, which may be
avoided by careful design.
.nr PS 9
.RT
.ad r
\fBTableau 5/G.761 [T5.761] p.\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.sp 3
.ce
\fBH.T. [T6.761]\fR 
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(180p) .
TABLE\ 6/G.761
.T&
cw(180p) .
 {
\fBUse of bits 7 and 8 of TS0 not containing the frame\fR
\fBalignment signal in stream C\fR
 }
.TE
.TS
center box;
cw(42p) | cw(24p) | cw(24p) | cw(90p) .
Bit number	7	8	Meaning
_
.T&
cw(42p) | cw(24p) | cw(24p) | lw(90p) , ^  | c | c | l 
^  | c | c | l 
^  | c | c | l.
States	1	0	AIS stream A
	0	1	AIS stream B	0	0	Normal	1	1	 {
Indicates that the safeguarding option
(see \(sc\ 3.10) is being used
 }
_
.TE
.nr PS 9
.RT
.ad r
\fBTableau 6/G.761[T6.761] p.\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.sp 1P
.LP
2.6.3
	\fIAlarm indication to the remote end for stream A (respectively B)\fR 
.sp 9p
.RT
.PP
In the send side, bit 3 of TS0, not containing the frame alignment signal 
of stream\ A (respectively\ B) should be transferred to bit\ 3 
(respectively\ 4) of the corresponding TS0 of stream\ C.
.PP
In the receive side, bit 3 (respectively 4) of TS0 not containing the frame 
alignment signal of stream\ C should be transferred to bit\ 3 of the 
corresponding TS0 of stream\ A (respectively\ B).
.RT
.sp 1P
.LP
2.6.4
	\fIAIS in TS16 of stream C\fR 
.sp 9p
.RT
.PP
For channel associated signalling, this means that a fault
condition, common to the signalling information associated with all 60 
channels of stream\ C has been detected in the send side. \*QAIS in TS16 
of stream\ C\*U is 
transmitted as an all ones configuration in TS16.
.RT
.sp 1P
.LP
2.6.5
	\fIAIS in TS16 stream A (respectively B)\fR 
.sp 9p
.RT
.PP
For channel associated signalling, this means that a fault, common to the 
30\ channels of stream A (respectively\ B), has been detected in the send 
side. 
.PP
For the send side, the following applies:
.PP
When \*QAIS in TS16 stream A\*U and \*QAIS in TS16 in stream B\*U are present 
simultaneously, then \*QAIS in TS16 of stream\ C\*U should be transmitted. 
When \*QAIS in TS16 stream A\*U (respectively B) is present, but not \*QAIS
in TS16 stream B\*U (respectively\ A), then the signalling information 
of stream\ B (respectively\ A) should be transmitted normally, and the 
signalling bits of 
TS16 of stream\ C associated with stream\ A (respectively\ B) should be
transmitted as an all ones configuration. In addition, bit\ 5 (respectively\ 
8) of TS16 frame\ 0 should be set to\ 1 to indicate \*QAIS in TS16 stream\ 
A\*U 
(respectively\ B).
.PP
For the receive side, the following applies:
.PP
AIS in TS16 stream A (respectively B) will be considered as being
present if bit\ 5 (respectively\ 8) of TS16 frame\ 0 is detected at state\ 
1 on two consecutive occasions. 
.PP
AIS in TS16 stream A (respectively B) will be considered as having
ceased if bit\ 5 (respectively\ 8) is detected at state\ 0 on two consecutive
occasions.
.RT
.sp 1P
.LP
2.6.6
	\fIRemote alarm in TS16 of stream A (respectively B)\fR 
.sp 9p
.RT
.PP
For channel associated signalling, this means that a loss of
multiframe alignment in stream\ A (respectively\ B) has been detected in the
opposite direction of transmission.
.PP
Bit 6 (respectively 7) of TS16 frame 0 of stream C should be put to 1 to 
transmit this remote alarm indication associated with stream\ A 
(respectively\ B).
.PP
The simultaneous presence of bits 6 and 7 (of TS16 frame 0 of stream C) 
in state\ 1 indicates a remote alarm associated with the signalling 
information of the 60\ channels.
.RT
.sp 2P
.LP
\fB3\fR 	\fBOther characteristics of the 60 channel transcoder equipment\fR 
.sp 1P
.RT
.sp 1P
.LP
3.1
	\fIInterfaces A and B\fR 
.sp 9p
.RT
.PP
The electrical characteristics of the two interfaces A and B are in accordance 
with Recommendation\ G.703, \(sc\ 6. 
.RT
.sp 1P
.LP
3.2
	\fIFrame structure of streams A and B\fR 
.sp 9p
.RT
.PP
The frame structure of the 2048 kbit/s streams A and B is given in Recommendation\ 
G.704, \(sc\ 2.3, with bit\ 1 of time slot\ 0 used for the CRC 
procedure. The strategy for loss and recovery of frame alignment and CRC
multiframe alignment are given in Recommendation\ G.706, \(sc\ 4.
.PP
As indicated in Recommendation G.704, \(sc 5.1, TS16 of streams A and B 
can be used for the transmission of telephone signals, if not used for 
signalling purposes, providing two supplementary channels nominated 31A 
and\ 31B respectively. (See Table\ 1/G.761.) 
.bp
.RT
.sp 1P
.LP
3.3
	\fITransparent transfer of bits of time slot 0 not containing the\fR 
\fIframe alignment signal\fR 
.sp 9p
.RT
.PP
The transcoder equipment should be capable of providing the
following two options, the choice between these to be made by the individual
Administration or by mutual agreement of the Administrations
concerned:
.RT
.LP
	a)
	bit 4 of time slot 0 not containing the frame alignment
signal of streams\ A and\ B should be transparently transmitted in
stream\ C using bits\ 5 and\ 6 respectively of time slot 0 not
containing the frame alignment signal of stream\ C;
.LP
	b)
	bit 5 should be transmitted in a corresponding way using
bits\ 5 and\ 6 respectively of stream\ C.
.sp 1P
.LP
3.4
	\fIMultiframe structure in TS16 of streams A and B\fR 
.sp 9p
.RT
.PP
When used for channel associated signalling, TS16 of streams A
and\ B is organized in multiframes as defined in Recommendation\ G.704,
\(sc\ 5.1.3. The definition of the alarm indications and the criteria for
multiframe alignment loss and recovery are given in Recommendation\ G.735.
.RT
.sp 1P
.LP
3.5
	\fIAbsolute delay\fR 
.sp 9p
.RT
.PP
The overall absolute delay introduced by a pair of interconnected transcoders 
(i.e. PCM to PCM) should be less than 500\ microseconds for any of the 
32\ kbit/s channels and for any of the transparently transferred 64\ kbit/s 
channels. 
.PP
In the case of channel associated signalling, the overall delay
introduced by a pair of interconnected transcoders (i.e. PCM to PCM) should 
be less than 3\ milliseconds for any of the signalling channels. 
.RT
.sp 2P
.LP
3.6
	\fISynchronization\fR 
.sp 1P
.RT
.sp 1P
.LP
3.6.1
	\fISend side\fR 
.sp 9p
.RT
.PP
So that the equipment may be inserted into a plesiochronous
network, or into a synchronous network operating in degraded conditions, 
both PCM ports\ A and\ B at the send side should be provided with frame 
and multiframe resynchronizing devices, which initiate controlled sample 
slips (i.e. sample 
repetitions or deletions) as required.
.PP
It should be possible to synchronize the sending side to any one of
the following:
.RT
.LP
	\(em
	timing signal associated with incoming PCM stream A;
.LP
	\(em
	timing signal associated with incoming PCM stream B;
.LP
	\(em
	timing signal associated with incoming stream C;
.LP
	\(em
	external 2048 kHz timing signal (see Recommendation\ G.703,
\(sc\ 10).
.PP
In the case of synchronization failure, the consequent action is a prompt 
maintenance alarm (see Table\ 8/G.761). 
.PP
\fINote\fR \ \(em\ Synchronization failure is assumed in case of a fault
condition (see Note\ 2 to Table\ 8/G.761) on the incoming signal being 
used for synchronization. 
.RT
.sp 1P
.LP
3.6.2
	\fIReceive side\fR 
.sp 9p
.RT
.PP
The receiving side should be synchronized to the timing signal
associated with incoming stream\ C.
.PP
\fINote\fR \ \(em\ The organization of the network should be such that
controlled sample slips are avoided in normal operating conditions. This can
lead to the need to synchronize the sending side to the receiving side in
remote 30\ channel PCM terminals. In circumstances where slips are unavoidable, 
they will affect both 32\ kbit/s channels and directly transferred 64\ 
kbit/s 
channels.
.RT
.sp 1P
.LP
3.7
	\fIJitter\fR 
.sp 9p
.RT
.PP
The basic jitter requirements at interfaces are covered by the
requirements of \(sc\(sc\ 2.1 and\ 3.1.
.PP
When the sending side of the transcoder is synchronized to the
incoming PCM stream\ A or\ B, and provided both streams\ A and\ B are synchronized 
to each other, slips should not occur when sinusoidal jitter having an 
amplitude lower then the maximum tolerable input jitter (see Figure\ 2/G.823) 
is present at one or both the input ports\ A and\ B. 
.PP
Jitter transfer characteristics between various signal ports are under study.
.bp
.RT
.sp 1P
.LP
3.8
	\fIDirect time slot transfer\fR 
.sp 9p
.RT
.PP
It should be possible to manually programme the transcoder to
transfer transparently at least two time slots from each of the two incoming
PCM streams\ A and\ B into stream\ C.
.PP
For national applications, it is sometimes necessary to use more than two 
signalling bits per channel. In such cases, time slot\ 16 from PCM streams\ 
A and\ B should be transferred to/from time slots\ 16 and\ 17 respectively 
of 
stream\ C. The special processing of signalling bits as described in \(sc\ 
2.5.1.1.3 will not be required. 
.PP
To be compatible with Recommendation G.735, \(sc 2, at least TS6 and TS22 
of each PCM stream\ A and\ B should be transferable. The positions of these 
time slots in the stream\ C frame are given below: 
.RT
.LP
	\(em
	TS6 of PCM stream A into TS5 of stream C;
.LP
	\(em
	TS6 of PCM stream B into TS6 of stream C;
.LP
	\(em
	TS22 of PCM stream A into TS22 of stream C;
.LP
	\(em
	TS22 of PCM stream B into TS23 of stream C.
.PP
In the case of the transfer of more than two time slots,
Table\ 7/G.761 indicates the allocation up to the maximum possible, taking
account of the priority ordering given in Recommendation\ G.735, \(sc\ 2.
.PP
If (n) 64 kbit/s time slots of PCM stream A (respectively B) are
transferred transparently through the transcoder, then the transmission
capabilities of PCM stream\ A (respectively\ B) will be limited to (30\(em2n)
channels. More precisely, with the frame structure of stream\ C given in
\(sc\ 2.2:
.RT
.LP
	\(em
	 when TS6 is transferred transparently, channel 5 of the same PCM stream 
cannot be used; 
.LP
	\(em
	when TS22 is transferred transparently, channel 22 of the
same PCM stream cannot be used.
.PP
In the case of direct transfer, the transcoder will restitute the binary 
mark sequence corresponding to amplitude\ 1 for coding law\ A (see 
Recommendation\ G.712, \(sc\ 4.3), in the non\(hyusable time slot of PCM output
streams\ A and\ B.
.PP
\fINote\ 1\fR \ \(em\ The need to transmit transparently more than two time
slots per incoming PCM stream is under study.
.PP
\fINote\ 2\fR \ \(em\ The possibility of remotely controlling the choice 
of the time slots which are to be transmitted transparently is under study. 
.PP
\fINote\ 3\fR \ \(em\ The octet sequence integrity is maintained by the
transcoder in the case of direct transfer of several time slots at
64\ kbit/s.
.RT
.sp 1P
.LP
3.9
	\fIIn\(hyservice monitoring\fR 
.sp 9p
.RT
.PP
When the PCM to ADPCM and/or the ADPCM to PCM processing functions are 
multiplexed for 60 channels, in\(hyservice monitoring of these processing 
functions should be provided. This in\(hyservice monitoring should be implemented 
in such a way that it it possible to distinguish between failures affecting 
the send and receive sides separately. 
.PP
Since no PCM (respectively ADPCM) signals are transmitted in TS0, the in\(hyservice 
monitoring can be implemented by inserting test signals into extra channels 
corresponding to TS0 of PCM streams\ A and\ B. 
.RT
.sp 1P
.LP
3.10
	\fISafeguarding of one PCM stream A or B\fR 
.sp 9p
.RT
.PP
As an option, safeguarding of one PCM tributary can be provided
automatically, or otherwise, when a failure of the transcoder digital
processing parts, or of the transcoder power supplies, have been detected. 
In this case the nominated PCM stream, A or\ B, should, for both directions 
of 
transmission, be made to bypass the transcoder and be connected to the
transmission link in place of the normal stream\ C signal.
.PP
The simultaneous presence at state 1 of bits 7 and 8 of TS0 not
containing the frame alignment signal in stream\ C on three consecutive
occasions is used to indicate to the remote transcoder that the downstream
transcoder has been switched to the safeguarding mode. When the safeguarding
option is provided automatically, the procedure for the exchange of information 
between the two transcoders when switching to and from the safeguarding 
mode is under study. 
.bp
.PP
\fINote\ 1\fR \ \(em\ The choice of the PCM stream ( A or B) which will be
safeguarded is made when the equipment is installed. It should be the same 
at both ends of the transmission link. 
.PP
\fINote\ 2\fR \ \(em\ The use of the safeguarding facility can result in two
2048\ kbit/s interfaces in cascade. It is then necessary to ensure, when
installing the transcoder, that the combined attenuation of the station 
cabling at 1024\ kHz on both sides of the transcoder is not greater than 
the maximum 
attenuation allowed by the equipment connected to the transcoder.
.PP
\fINote\ 3\fR \ \(em\ Before using the safeguarding facility, it should be
checked that the bits\ 7 and\ 8 of TS0 not containing the frame alignment 
signal of the PCM stream to be safeguarded are in the idle state\ 1 as 
specified in 
Recommendation\ G.704, \(sc\ 3.3.1.3.
.RT
.sp 2P
.LP
3.11
	\fIFault conditions\fR \fIand consequent actions\fR 
.sp 1P
.RT
.sp 1P
.LP
3.11.1
	\fIWithout safeguarding\fR 
.sp 9p
.RT
.PP
The fault conditions associated with the frames of streams A, B
and\ C and the consequent actions, when the safeguarding option is not 
used, are given in Table\ 8/G.761. 
.PP
When channel associated signalling is used, the fault conditions
associated with the multiframes of streams\ A, B and\ C and their consequent
actions are given in Table\ 9/G.761.
.RT
.sp 1P
.LP
3.11.2
	\fIWith safeguarding\fR 
.sp 9p
.RT
.PP
When the safeguarding option is provided, Tables 8/G.761 and
9/G.761 must be used, with the exception of the fault condition \*Qtranscoder
failure\*U of Table\ 8/G.761. Instead, the fault conditions and consequent 
actions given in Table\ 10/G.761 must be used, with reference to Figure\ 
2/G.761. 
.RT
.LP
.rs
.sp 30P
.ad r
Blanc
.ad b
.RT
.LP
.bp
.ce
\fBH.T. [T7.761]\fR 
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(180p) .
TABLE\ 7/G.761
.T&
cw(180p) .
 {
\fBOrder of priority for the transfer of 64 kbit/s time\fR
\fBslots from streams A or B to stream C\fR
 }
.TE
.TS
center box;
cw(60p) | cw(60p) | cw(60p) .
Time slot in  stream A	Time slot in  stream B	Time slot in  stream C
_
.T&
cw(60p) | cw(60p) | cw(60p) .
\ 6		\ 5
_
.T&
cw(60p) | cw(60p) | cw(60p) .
	\ 6	\ 6
_
.T&
cw(60p) | cw(60p) | cw(60p) .
22		22
_
.T&
cw(60p) | cw(60p) | cw(60p) .
	22	23
_
.T&
cw(60p) | cw(60p) | cw(60p) .
14		13
_
.T&
cw(60p) | cw(60p) | cw(60p) .
	14	14
_
.T&
cw(60p) | cw(60p) | cw(60p) .
30		30
_
.T&
cw(60p) | cw(60p) | cw(60p) .
	30	31
_
.T&
cw(60p) | cw(60p) | cw(60p) .
\ 2		\ 1
_
.T&
cw(60p) | cw(60p) | cw(60p) .
	\ 2	\ 2
_
.T&
cw(60p) | cw(60p) | cw(60p) .
18		18
_
.T&
cw(60p) | cw(60p) | cw(60p) .
	18	19
_
.T&
cw(60p) | cw(60p) | cw(60p) .
10		9
_
.T&
cw(60p) | cw(60p) | cw(60p) .
	10	10
_
.T&
cw(60p) | cw(60p) | cw(60p) .
26		26
_
.T&
cw(60p) | cw(60p) | cw(60p) .
	26	27
_
.T&
cw(60p) | cw(60p) | cw(60p) .
\ 4		\ 3
_
.T&
cw(60p) | cw(60p) | cw(60p) .
	\ 4	\ 4
_
.T&
cw(60p) | cw(60p) | cw(60p) .
20		20
_
.T&
cw(60p) | cw(60p) | cw(60p) .
	20	21
_
.T&
cw(60p) | cw(60p) | cw(60p) .
12		11
_
.T&
cw(60p) | cw(60p) | cw(60p) .
	12	12
_
.T&
cw(60p) | cw(60p) | cw(60p) .
28		28
_
.T&
cw(60p) | cw(60p) | cw(60p) .
	28	29
_
.T&
cw(60p) | cw(60p) | cw(60p) .
\ 8		\ 7
_
.T&
cw(60p) | cw(60p) | cw(60p) .
	\ 8	\ 8
_
.T&
cw(60p) | cw(60p) | cw(60p) .
24		24
_
.T&
cw(60p) | cw(60p) | cw(60p) .
	24	25
_
.T&
cw(60p) | cw(60p) | cw(60p) .
17  (Note 1)		15
_
.T&
cw(60p) | cw(60p) | cw(60p) .
	17  (Note 1)	17 (Note 2)
.TE
.LP
\fINote\ 1\fR
\ \(em\ This time slot does not comply with the normal priority ordering
given in Recommendation\ G.735, \(sc\ 2.
.LP
\fINote\ 2\fR
\ \(em\ Time slot 17 of stream C will not be available for direct transfer of time slot 17 of stream\ B when the PCM streams employ time slot 16\ channel
associated signalling with more than two signalling bits per channel
(see \(sc\ 2.5.1.2).
.nr PS 9
.RT
.ad r
\fBtableau 7/G.761 [T7.761], p. 8\fR 
.sp 1P
.RT
.ad b
.RT
.LP
\fR .bp
.ce
\fBH.T. [1T8.761]\fR 
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(342p) .
TABLE\ 8/G.761
.T&
cw(342p) .
 {
\fBFault conditions on frames A, B and C and consequent\fR
\fBactions without safeguarding\fR
 }
.TE
.TS
center box;
rw(60p) | cw(30p) | lw(24p) sw(24p) | lw(24p) sw(24p) | lw(24p) sw(24p) | lw(22p) sw(22p) | lw(16p) | lw(24p) sw(24p) , ^  | ^  | l | l | l s | ^ | ^ | ^ | ^ | ^ | ^ , ^  | ^  | ^  | ^  | l | l | l | l | l | l | l | l | l.
 {
Consequent
actions
Fault
conditions
 }	 {
Prompt maintenance alarm indication
Bit 3
TS0 not
containing
the FAS
stream
TS0 not
containing
the FAS
stream C
Stream C \(em
Apply into
bits in TSI\(hy31
associated
with stream
AIS
applied
to stream
AIS applied to stream
TS0 not
containing
the FAS
stream C
A
.
B
.
bit
3
4
A
(Note\ 2)
B
(Note\ 3)
A
.
B
.
C
.
bit
7
bit
8
 }						
				
												
_
.T&
lw(60p) | cw(30p) | lw(24p) | lw(24p) | lw(24p) | lw(24p) | cw(24p) | lw(24p) | lw(22p) | lw(22p) | lw(16p) | cw(24p) | lw(24p) .
PCM stream A (Note 1)	Yes (Note 4)					11 |  |  |  | 1					1	
_
.T&
lw(60p) | cw(30p) | lw(24p) | lw(24p) | lw(24p) | lw(24p) | cw(24p) | cw(24p) | lw(22p) | lw(22p) | lw(16p) | cw(24p) | cw(24p) .
PCM stream B (Note 1)	Yes  (Note 4)						11 |  |  |  | 1					1
_
.T&
lw(60p) | cw(30p) | lw(24p) | lw(24p) | lw(24p) | lw(24p) | cw(24p) | cw(24p) | lw(22p) | lw(22p) | cw(16p) | cw(24p) | cw(24p) .
PCM streams A and B  (Note 1)	Yes  (Note 4)									Yes		
_
.T&
lw(60p) | cw(30p) | lw(24p) | lw(24p) | lw(24p) | lw(24p) | cw(24p) | cw(24p) | cw(22p) | cw(22p) | cw(16p) | cw(24p) | cw(24p) .
Stream C (Note 1)	Yes  (Note 4)							Yes	Yes			
_
.T&
lw(60p) | cw(30p) | lw(24p) | lw(24p) | cw(24p) | lw(24p) | cw(24p) | cw(24p) | cw(22p) | cw(22p) | cw(16p) | cw(24p) | cw(24p) .
 {
TS0 stream A bit 3 to 1
(Note 6)
 }				1								
_
.T&
lw(60p) | cw(30p) | lw(24p) | lw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(22p) | cw(22p) | cw(16p) | cw(24p) | cw(24p) .
 {
TS0 stream B bit 3 to 1
(Note 6)
 }					1							
_
.T&
lw(60p) | cw(30p) | cw(24p) | lw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(22p) | cw(22p) | cw(16p) | cw(24p) | cw(24p) .
 {
TS0 stream C bit 3 to 1
(Note 6)
 }		1										
_
.T&
lw(60p) | cw(30p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(22p) | cw(22p) | cw(16p) | cw(24p) | cw(24p) .
 {
TS0 stream C bit 4 to 1
(Note 6)
 }			1									
_
.TE
.nr PS 9
.RT
.ad r
\fBtableau 8/G.761 [1T8.761], p. 9 \ \ \ A L'ITALIENNE\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.ce
\fBH.T. [2T8.761]\fR 
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(342p) .
 {
TABLE\ 8/G.761 \fI(cont.)\fR
 }
.TE
.TS
center box;
rw(60p) | cw(30p) | lw(24p) sw(24p) | lw(24p) sw(24p) | lw(24p) sw(24p) | lw(22p) sw(22p) | lw(16p) | lw(24p) sw(24p) , ^  | ^  | l | l | l s | ^ | ^ | ^ | ^ | ^ | ^ , ^  | ^  | ^  | ^  | l | l | l | l | l | l | l | l | l.
 {
Consequent
actions
Fault
conditions
 }	 {
Prompt maintenance alarm indication
Bit 3
TS0 not
containing
the FAS
stream
TS0 not
containing
the FAS
stream C
Stream C \(em
Apply into
bits in TS1\(hy31
associated
with stream 
AIS
applied
to stream
AIS
applied
to stream
TS0 not
containing
the FAS
stream C
A
.
B
.
bit
3
4
A
(Note\ 2)
B
(Note\ 3)
A
.
B
.
C
.
bit
7
bit
8
 }						
				
												
_
.T&
lw(60p) | lw(30p) | lw(24p) | lw(24p) | lw(24p) | lw(24p) | lw(24p) | lw(24p) | cw(22p) | lw(22p) | lw(16p) | lw(24p) | lw(24p) .
TS0 stream C bit 7 to 1								Yes				
_
.T&
lw(60p) | lw(30p) | lw(24p) | lw(24p) | lw(24p) | lw(24p) | lw(24p) | lw(24p) | cw(22p) | cw(22p) | lw(16p) | lw(24p) | lw(24p) .
TS0 stream C bit 8 to 1									Yes			
_
.T&
lw(60p) | cw(30p) | lw(24p) | lw(24p) | lw(24p) | lw(24p) | lw(24p) | lw(24p) | cw(22p) | cw(22p) | cw(16p) | lw(24p) | lw(24p) .
 {
Transcoder failure, send side (Note 5)
 }	Yes									Yes		
_
.T&
lw(60p) | cw(30p) | lw(24p) | lw(24p) | lw(24p) | lw(24p) | lw(24p) | lw(24p) | cw(22p) | cw(22p) | cw(16p) | lw(24p) | lw(24p) .
 {
Transcoder failure, receive side (Note 5)
 }	Yes							Yes	Yes			
_
.T&
lw(60p) | cw(30p) | lw(24p) | lw(24p) | lw(24p) | lw(24p) | lw(24p) | lw(24p) | cw(22p) | cw(22p) | cw(16p) | lw(24p) | lw(24p) .
Power supply failure	Yes							Yes if possible	Yes if possible	Yes if possible		
_
.T&
lw(60p) | cw(30p) | lw(24p) | lw(24p) | lw(24p) | lw(24p) | lw(24p) | lw(24p) | cw(22p) | cw(22p) | cw(16p) | lw(24p) | lw(24p) .
 {
Synchronization failure of the sending side
 }	Yes											
.TE
.LP
\fINote\ 1\fR
\ \(em\ The fault conditions associated with streams A, B and C are:
loss of signal, loss of frame alignment, error ratio greater than
10\uD\dlF261\u3\d as defined in Recommendation\ G.735, \(sc\ 4.1.
.LP
\fINote\ 2\fR
\ \(em\ Only in time slots and signalling bits associated with PCM
stream A (both for 32 and 64\ kbit/s channels).
.LP
\fINote\ 3\fR
\ \(em\ Only in time slots and signalling bits associated with PCM
stream B (both for 32 and 64\ kbit/s channels).
.LP
\fINote\ 4\fR
\ \(em\ The prompt maintenance alarm indication must be inhibited if the
AIS is detected at the corresponding port.
.LP
\fINote\ 5\fR
\ \(em\ The fault condition \*Qtranscoder failure\*U is detected by the
in\(hyservice monitoring unit. The transcoder is equipped with such a unit if the digital signal processing is time\(hymultiplexed between the 60\(hychannels.
.LP
\fINote\ 6\fR
\ \(em\ These fault conditions are not detected by the transcoder.
The indications pass transparently through the transcoder (see
\(sc\ 2.6.3).
.nr PS 9
.RT
.ad r
\fBtableau 8/G.761 [2T8.761], p. 10\ \ \ A L'ITALIENNE\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.ce
\fBH.T. [T9.761]\fR 
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(342p) .
TABLE\ 9/G.761
.T&
cw(342p) .
 {
\fBFault conditions on multiframes A, B and C and consequent\fR
\fBactions\fR
 }
.TE
.TS
center box;
rw(60p) | cw(30p) | lw(24p) sw(24p) | lw(24p) sw(24p) | lw(24p) sw(24p) | lw(22p) sw(22p) | lw(16p) | lw(24p) sw(24p) , ^  | ^  | l | l | l | l | l | l | l | l | l | l | l.
 {
Consequent
actions
Fault
conditions
 }	 {
Prompt maintenance alarm indication
TS 16
frame 0
bit 6
TS 16
frame 0
stream C
TS 16
stream C
frames 1\(hy15
AIS
TS 16
AIS
TS 16
TS 16
frame 0
stream C
A
.
B
.
6
.
7
.
A
(Note\ 2)
B
(Note\ 3)
A
.
B
.
C
.
bit
5
bit
8
 }						
												
_
.T&
lw(60p) | cw(30p) | lw(24p) | lw(24p) | lw(24p) | lw(24p) | cw(24p) | lw(24p) | lw(22p) | lw(22p) | lw(16p) | cw(24p) | lw(24p) .
Multiframe A (Note 1)	Yes  (Note 4)					1111					1	
_
.T&
lw(60p) | cw(30p) | lw(24p) | lw(24p) | lw(24p) | lw(24p) | cw(24p) | cw(24p) | lw(22p) | lw(22p) | lw(16p) | cw(24p) | cw(24p) .
Multiframe B (Note 1)	Yes  (Note 4)						1111					1
_
.T&
lw(60p) | cw(30p) | lw(24p) | lw(24p) | lw(24p) | lw(24p) | cw(24p) | cw(24p) | lw(22p) | lw(22p) | cw(16p) | cw(24p) | cw(24p) .
Multiframe A and B  (Note 1)	Yes  (Note 4)									Yes		
_
.T&
lw(60p) | cw(30p) | lw(24p) | lw(24p) | lw(24p) | lw(24p) | cw(24p) | cw(24p) | cw(22p) | cw(22p) | cw(16p) | cw(24p) | cw(24p) .
Multiframe C (Note 1)	Yes  (Note 4)							Yes	Yes			
_
.T&
lw(60p) | cw(30p) | lw(24p) | lw(24p) | cw(24p) | lw(24p) | cw(24p) | cw(24p) | cw(22p) | cw(22p) | cw(16p) | cw(24p) | cw(24p) .
 {
Bit 6 TS 16 frame 0
stream A to 1 (Note 5)
 }				1								
_
.T&
lw(60p) | cw(30p) | lw(24p) | lw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(22p) | cw(22p) | cw(16p) | cw(24p) | cw(24p) .
 {
Bit 6 TS 16 frame 0
stream B to 1 (Note 5)
 }					1							
_
.T&
lw(60p) | cw(30p) | cw(24p) | lw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(22p) | cw(22p) | cw(16p) | cw(24p) | cw(24p) .
 {
Bit 6 TS 16 frame 0
stream C to 1 (Note 5)
 }		1										
_
.T&
lw(60p) | cw(30p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(22p) | cw(22p) | cw(16p) | cw(24p) | cw(24p) .
 {
Bit 7 TS 16 frame 0
stream C to 1 (Note 5)
 }			1									
_
.T&
lw(60p) | cw(30p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(22p) | cw(22p) | cw(16p) | cw(24p) | cw(24p) .
 {
Bit 5 TS 16 frame 0
stream C to 1
 }								Yes				
_
.T&
lw(60p) | cw(30p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) | cw(22p) | cw(22p) | cw(16p) | cw(24p) | cw(24p) .
 {
Bit 8 TS 16 frame 0
stream C to 1
 }									Yes			
.TE
.LP
\fINote\ 1\fR
\ \(em\ The fault condition associated with the three multiframes is the
loss of multiframe alignment.
.LP
\fINote\ 2\fR
\ \(em\ Only in signalling bits associated with PCM stream\ A. The 1111.... bits are processed in accordance with \(sc\ 2.5.1.1.3 and Tables\ 4/G.761 and
5/G.761.
.LP
\fI\fR
\fINote\ 3\fR
\ \(em\ Only in signalling bits associated with PCM stream\ B. The 1111.... bits are processed in accordance with \(sc\ 2.5.1.1.3 and Tables\ 4/G.761 and
5/G.761.
.LP
\fINote\ 4\fR
\ \(em\ The prompt maintenance alarm indication must be inhibited if the
AIS in TS16 is detected at the corresponding port.
.LP
\fINote\ 5\fR
\ \(em\ These fault conditions are not detected by the transcoder. The
indications pass transparently through the transcoder (see \(sc\ 2.6.6).
.nr PS 9
.RT
.ad r
\fBtableau 9/G.761 [T9.761], p. 11\ \ \ A L'ITALIENNE\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.ce
\fBH.T. [T10.761]\fR 
.ce
TABLE\ 10/G.761
.ce
\fBFault conditions and consequent actions when\fR 
.ce
\fBimplementing the safeguarding option\fR 
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
rw(90p) | lw(30p) sw(30p) | lw(30p) sw(30p) , ^  | l | l | l | l.
 {
Consequent
actions
Fault conditions
Switching to the
safeguarding mode
AIS in PCM stream
not safeguarded
at (1)
at (2)
at (1)
at (2)
 }		
				
_
.T&
lw(90p) | cw(30p) | lw(30p) | cw(30p) | cw(30p) .
Transcoder failure at (1)	Yes		Yes   if possible	Yes
_
.T&
lw(90p) | cw(30p) | lw(30p) | cw(30p) | cw(30p) .
Power supply failure at (1)	Yes		Yes  if possible	Yes
_
.T&
lw(90p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) .
 {
TS0 stream C from (1) to (2) bits 7 and 8 in state\ 1
 }		Yes		Yes
.TE
.LP
\fINote\fR
\ \(em\ The transcoder designations (1) and (2) are indicated in
Figure\ 2/G.761.
.nr PS 9
.RT
.ad r
\fBtableau 10/G.761 [T10.761], p. 12\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.rs
.sp 10P
.ad r
\fBfigure\ 2/G.761 p. 13\fR 
.sp 1P
.RT
.ad b
.RT
.sp 2P
.LP
\fBRecommendation\ G.762\fR 
.RT
.sp 2P
.ce 1000
\fBGENERAL\ CHARACTERISTICS\ OF\ A\ 48\(hyCHANNEL\fR 
.EF '%	Fascicle\ III.4\ \(em\ Rec.\ G.762''
.OF '''Fascicle\ III.4\ \(em\ Rec.\ G.762	%'
.ce 0
.sp 1P
.ce 1000
\fBTRANSCODER\ EQUIPMENT\fR 
.ce 0
.sp 1P
.ce 1000
\fI(Melbourne, 1988)\fR 
.sp 9p
.RT
.ce 0
.sp 1P
.LP
\fB1\fR 	\fBGeneral\fR 
.sp 1P
.RT
.PP
The 48\(hychannel transcoder provides for the conversion between two 24\(hychannel 
1544\ kbit/s PCM streams and one 48\(hychannel 1544\ kbit/s ADPCM stream. 
In the 24\(hychannel 1544\ kbit/s streams, the voice\(hyfrequency signals 
are coded 
at 64\ kbit/s according to the PCM \(*m\(hylaw defined in Recommendation\ 
G.711. 
In the 48\(hychannel 1544\ kbit/s stream, the voice\(hyfrequency signals 
are coded 
at 32\ kbit/s according to the ADPCM encoding law defined in
Recommendation\ G.721.
.bp
.PP
Figure 1/G.762 represents the nomenclature used for the three
different signal ports\ X, Y and\ Z.
.RT
.LP
.rs
.sp 20P
.ad r
\fBFigure 1/G.762, p.\fR 
.sp 1P
.RT
.ad b
.RT
.PP
The 1544 kbit/s stream associated with port Z can be partitioned into four 
independent 384\ kbit/s entities defined as time slot groupings. Each 384\ 
kbit/s time slot grouping consists of twelve 32\ kbit/s time slots which 
can be used to transport up to 12\ voice\(hyfrequency channels or 11\ voice\(hyfrequency 
channels plus their channel associated a\(hyb\(hyc\(hyd signalling information.
Therefore, the 1544\ kbit/s stream associated with port\ Z will have a maximum
channel capacity of between 44\ and 48\ voice\(hyfrequency channels.
.PP
\fINote\ 1\fR \ \(em\ Administrations should take into account the guidance 
given in Recommendation\ G.721 concerning the use and transmission performance 
of 
32\ kbit/s ADPCM.
.PP
\fINote\ 2\fR \ \(em\ It should be noted that the transcoder equipment 
described in this Recommendation has a limited capability of transparently 
transporting 64\ kbit/s data channels and this should be taken into account 
in the planning of networks which are likely to evolve into an ISDN (see 
\(sc\ 4.4). 
.PP
This Recommendation is divided into three parts:
.RT
.LP
	\(em
	Paragraph 2 contains the interface requirements associated
with port\ Z;
.LP
	\(em
	Paragraph 3 contains the interface requirements associated
with ports X and\ Y;
.LP
	\(em
	Paragraph 4 contains the requirements which are specific to a
48\(hychannel transcoder equipment realization.
.bp
.sp 2P
.LP
\fB2\fR \fBCharacteristics of a 1544 kbit/s signal organized in 32 kbit/s 
and/or 64 kbit/s time slots (port Z)\fR 
.sp 1P
.RT
.sp 1P
.LP
2.1
	\fIInterface Z\fR 
.sp 9p
.RT
.PP
The electrical characteristics of the 1544 kbit/s interface are in accordance 
with \(sc\ 2 of Recommendation\ G.703. 
.RT
.sp 2P
.LP
2.2
	\fIFrame structure\fR 
.sp 1P
.RT
.sp 1P
.LP
2.2.1
	\fIFrame structure at 1544 kbit/s\fR 
.sp 9p
.RT
.PP
Refer to \(sc\ 3.2.1 of Recommendation G.704 for the frame structure
and use of derived channel time slots.
.RT
.sp 1P
.LP
2.2.2
	\fIFrame structure at 384 kbit/s\fR 
.sp 9p
.RT
.PP
Refer to \(sc\ 3.2.3 of Recommendation G.704 for the frame structure at 
384\ kbit/s. 
.RT
.sp 2P
.LP
2.3
	\fILoss and recovery of frame and multiframe alignment\fR 
.sp 1P
.RT
.sp 1P
.LP
2.3.1
	\fILoss and recovery of 1544 kbit/s frame and multiframe alignment\fR 
.sp 9p
.RT
.PP
The criteria for loss and recovery of the frame alignment and
multiframe alignment signal for port\ Z are in accordance with \(sc\ 2.1 of
Recommendation\ G.706 for the 24\(hyframe multiframe and for the 12\(hyframe
multiframe.
.RT
.sp 1P
.LP
2.3.2
	\fILoss and recovery of delta channel multiframe alignment\fR 
.sp 9p
.RT
.PP
The criteria for loss and recovery of the signalling grouping
channel multiframe alignment signal are in accordance with \(sc\ 3.2.6 of
Recommendation\ G.704.
.RT
.sp 1P
.LP
2.4
	\fISignalling\fR 
.sp 9p
.RT
.PP
Refer to \(sc\ 3.2.4 of Recommendation G.704 for signalling in the
384\ kbit/s stream.
.RT
.sp 2P
.LP
\fB3\fR 	\fBCharacteristics of ports X and Y\fR 
.sp 1P
.RT
.sp 1P
.LP
3.1
	\fIInterfaces X and Y\fR 
.sp 9p
.RT
.PP
The electrical characteristics of the 1544 kbit/s interface are in accordance 
with \(sc\ 2 of Recommendation\ G.703. 
.RT
.sp 1P
.LP
3.2
	\fIFrame structure\fR 
.sp 9p
.RT
.PP
Refer to \(sc\ 2.1 of Recommendation G.704 for the frame structure and 
use of derived channel time slots. 
.RT
.sp 1P
.LP
3.3
	\fILoss and recovery of 1544 kbit/s frame and multiframe alignment\fR 
.sp 9p
.RT
.PP
The criteria for loss and recovery of the frame alignment and
multiframe alignment signal for ports\ X and\ Y are in accordance with 
\(sc\ 2.1 of Recommendation\ G.706 for the 24\(hyframe alignment and for 
the 12\(hyframe 
multiframe.
.RT
.sp 1P
.LP
3.4
	\fISignalling\fR 
.sp 9p
.RT
.PP
Refer to \(sc\ 3.1.3 of Recommendation G.704 and \(sc\ 4.3 below.
.bp
.RT
.sp 2P
.LP
\fB4\fR 	\fBOther characteristics of the\fR 
\fB48\(hychannel transcoder
equipment\fR 
.sp 1P
.RT
.sp 1P
.LP
4.1
	\fI48\(hychannel frame\fR \fIstructure\fR 
.sp 9p
.RT
.PP
In the case where streams X and Y are each carrying 24
voice\(hyfrequency signals and no channel\(hyassociated signalling information 
is 
present, stream\ Z will transmit the full complement of 48\ channels.
Table\ 1/G.762 shows the correspondence between the 64\ kbit/s PCM channels in
streams\ X and\ Y and the 32\ kbit/s ADPCM channels in stream\ Z. Time 
slots 1\(hy12 correspond to channels 1\(hy12 from PCM stream\ X coded with 
4\ bits. Time slots 
13\(hy24 correspond to channels 13\(hy24 from PCM stream\ X coded with 
4\ bits. Time 
slots 25\(hy36 correspond to channels 1\(hy12 from PCM stream\ Y coded 
with 4\ bits. 
Time slots 37\(hy48 correspond to channels 13\(hy24 from PCM stream\ Y 
coded with 
4\ bits.
.RT
.ce
\fBH.T. [T1.762]\fR 
.ce
TABLE\ 1/G.762
.ce
\fBOrganization of the 1544 kbit/s frame for up to 48\fR 
.ce
\fBchannels at 32 kbit/s in stream Z\fR 
.T&
lw(42p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) 
| cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | lw(42p) , l | c | c 
| c | c | c | c | c | c | c | c | c | c | ^ . 
4 bit time slot of stream Z	1	2	3	4	5	6	7	8	9	10	11	12	Time slot  Grouping 1  
8 bit channel of stream X 	1X	2X	3X	4X	5X	6X	7X	8X	9X	10X	11X	12X or SGC
.T&
lw(186p) .
.T&
lw(42p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) 
| cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | lw(42p) , l | c | c 
| c | c | c | c | c | c | c | c | c | c | ^ . 
4 bit time slot of stream Z 13 14 15 16 17 18 19 20 21 22 23 24 Time slot 
Grouping\ 2 
8 bit channel of stream X 13X 14X 15X 16X 17X 18X 19X 20X 21X 22X 23X 24X 
or SGC 
.T&
lw(186p) .
.T&
lw(42p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) 
| cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | lw(42p) , l | c | c 
| c | c | c | c | c | c | c | c | c | c | ^ . 
4 bit time slot of stream Z 25 26 27 28 29 30 31 32 33 34 35 36 Time slot 
Grouping\ 3 
8 bit channel of stream Y	1Y	2Y	3Y	4Y	5Y	6Y	7Y	8Y	9Y	10Y	11Y	12Y or SGC
.T&
lw(186p) .
.T&
lw(42p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) 
| cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | lw(42p) , l | c | c 
| c | c | c | c | c | c | c | c | c | c | ^ . 
4 bit time slot of stream Z 37 38 39 40 41 42 43 44 45 46 47 48 Time slot 
Grouping\ 4 
8 bit channel of stream Y 13Y 14Y 15Y 16Y 17Y 18Y 19Y 20Y 21Y 22Y 23Y 24Y 
or SGC 
.TE
.nr PS 9
.RT
.ad r
\fBTable 1/G.762 [T1.762], p.\fR 
.sp 1P
.RT
.ad b
.RT
.PP
.sp 3
The signalling grouping channels for time slot groupings 1\(hy4,
when present in stream\ Z, occupy time slots\ 12, 24, 36 and\ 48 respectively. 
As shown in Table\ 2/G.762, the channel capacity for stream\ X (respectively\ 
Y) is reduced by one for each time slot grouping associated with stream\ 
X 
(respectively\ Y) configured with a signalling grouping channel. Selection of
the 
time slot grouping\fR 
format to include the 
signalling grouping
.LP
channel (SGC)
is made on a per\(hytime slot grouping basis, independent of
the other time slot groupings associated with stream\ X or\ Y.
.bp
.LP
.ce
\fBH.T. [T2.762]\fR 
.ce
TABLE\ 2/G.762
.ce
\fBUnused channels in streams X and Y when the signalling\fR 
.ce

.ce
\fBgrouping channel is present in a time slot grouping\fR 
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(90p) | cw(72p) .
 {
Signalling grouping channel present
 }	Unused channel
_
.T&
lw(90p) | lw(72p) .
Time slot grouping 1	Channel 12 in stream X
.T&
lw(90p) | lw(72p) .
Time slot grouping 2	Channel 24 in stream X
.T&
lw(90p) | lw(72p) .
Time slot grouping 3	Channel 12 in stream Y
.T&
lw(90p) | lw(72p) .
Time slot grouping 4	Channel 24 in stream Y
_
.TE
.nr PS 9
.RT
.ad r
\fBTable 2/G.762 [T2.762], p.\fR 
.sp 1P
.RT
.ad b
.RT
.sp 1P
.LP
4.1.1
	\fIUnused channels\fR 
.sp 9p
.RT
.PP
As explained in \(sc 4.1, the presence of a signalling grouping
channel in a time slot grouping causes a given channel in stream\ X or\ 
Y to be configured as unused. 
.PP
The unused channels on the receive side of streams X and Y should have 
their data and signalling bits conditioned in a way that is compatible 
with 
downstream equipment.
.PP
The unused channels on the send side of streams X and Y are not
processed.
.RT
.sp 1P
.LP
4.2
	\fISelection of 1544 kbit/s multiframe formats\fR 
.sp 9p
.RT
.PP
Selection of either the 24\(hyframe or 12\(hyframe multiframe format at 
ports\ X, Y or\ Z is independent of the multiframe frame formats selected 
at the other ports. 
.RT
.sp 2P
.LP
4.3
	\fISignalling\fR 
.sp 1P
.RT
.sp 1P
.LP
4.3.1
	\fICommon\(hychannel signalling\fR 
.sp 9p
.RT
.PP
A channel being used to convey common\(hychannel signalling
information in stream\ X or\ Y will not undergo the transcoding function. The
signalling channel will be transmitted transparently in stream\ Z at the
64\ kbit/s rate, as can other channels from streams\ X and\ Y in accordance 
with \(sc\ 4.4. 
.RT
.sp 1P
.LP
4.3.2
	\fIChannel\(hyassociated signalling\fR 
.sp 9p
.RT
.PP
Refer to Table 1/G.762 and Table 7/G.704 for the association of
channel associated a\(hyb\(hyc\(hyd signalling bits between streams\ X 
and\ Y and the 
signalling grouping channels in stream\ Z.
.RT
.sp 1P
.LP
4.4
	\fIDirect time slot transfer\fR 
.sp 9p
.RT
.PP
It should be possible to select and pass through 64 kbit/s channels from 
streams\ X and\ Y transparently into stream\ Z. Furthermore, it should 
be 
possible to pass through at least one 64\ kbit/s channel in each time slot
grouping stream\ Z.
.PP
The priority for selecting which time slots from streams\ X and\ Y
should be directly transferred and their placement into stream\ Z is for 
further study. 
.RT
.sp 1P
.LP
4.4.1
	\fIChannel\(hyassociated signalling in 64 kbit/s pass\(hythrough time\fR 
\fIslots\fR 
.sp 9p
.RT
.PP
The transcoder should allow for selection of reinsertion or no
reinsertion of channel\(hyassociated signalling bits into the receive side of
streams\ X and\ Y for channels which are passed\(hythrough transparently at
64\ kbit/s.
.RT
.sp 1P
.LP
4.4.2
	\fIConditioning of unused channels\fR 
.sp 9p
.RT
.PP
When 64 kbit/s channels from stream\ X (respectively\ Y) are
transferred transparently into stream\ Z, the transmission capacity of PCM
stream\ X (respectively\ Y) is reduced. The unused channels in stream\ X
(respectively\ Y) should be conditioned as described in \(sc\ 4.1.1.
.bp
.RT
.sp 1P
.LP
4.5
	\fISignalling grouping channel alarm indications\fR 
.sp 9p
.RT
.PP
When signalling grouping channel frame alignment is lost (as per
\(sc\ 3.2.6 of Recommendation\ G.704), updating of the channel\(hyassociated
signalling bits on the receive side of streams\ X and\ Y should be inhibited 
for the affected channels until frame alignment is regained. 
.PP
A time slot grouping alarm is declared when the signalling grouping
channel multiframe alignment signal is lost for 2\ to 3\ seconds.
.PP
When signalling grouping channel multiframe alignment is declared (as per 
\(sc\ 3.2.6 of Recommendation\ G.704), updating of the channel\(hyassociated 
signalling bits on the receive side of streams\ X and\ Y will be enabled.
.PP
The time slot grouping alarm is released when signalling grouping
channel multiframe alignment has been reacquired for 10\ to 20\ seconds.
.PP
On the send side, M\d1\uis set to 1 to transmit a time slot grouping alarm 
to the remote end when the near end is in time slot grouping alarm. On 
the receive side, a remote time slot grouping alarm is declared when\ M\d1\uhas 
been set for 335\ to 1000\ milliseconds. Remote time slot grouping alarm 
is 
released when M\d1\uhas been reset for 20\ to 1000\ milliseconds.
.PP
On the send side, M\d2\uis used to indicate a 1544\ kbit/s alarm or a 1544\ 
kbit/s AIS has been received on port\ X (time slot groupings\ 1 or\ 2) 
or 
port\ Y (time slot groupings\ 3 or\ 4). On the receive side, a signalling
grouping channel AIS alarm is declared when M\d2\uhas been set for 335\ to
1000\ milliseconds. Signalling grouping channel AIS is released
when\ M\d2\uhas been reset for 20\ to 1000\ milliseconds.
.PP
On the send side, M\d3\uis used to indicate a remote 1544\ kbit/s alarm 
has been received on port\ X (time slot groupings\ 1 or\ 2) or port\ Y 
(time slot groupings\ 3 or\ 4). On the receive side, a remote signalling 
grouping channel 
AIS alarm is declared when M\d3\uhas been set for 335\ to 1000\ milliseconds.
Signalling grouping channel remote AIS alarm is released when M\d3\uhas been
reset for 20\ to 1000\ milliseconds.
.RT
.sp 2P
.LP
4.6
	\fIFault conditions and consequent actions\fR 
.sp 1P
.RT
.sp 1P
.LP
4.6.1
	\fI1544 kbit/s fault conditions associated with stream Z\fR 
.sp 9p
.RT
.PP
A summary of the 1544 kbit/s fault conditions associated with the receive 
side of stream\ Z and the consequent actions are listed in 
Table\ 3/G.762.
.PP
The transcoder shall detect the following 1544 kbit/s fault conditions 
associated with stream\ Z: 
.RT
.LP
	i)
	loss of incoming signals at 1544 kbit/s;
.LP
	ii)
	loss of 1544 kbit/s frame alignment;
.LP
	iii)
	1544 kbit/s alarm indication signal (AIS) received;
.LP
	iv)
	1544 kbit/s alarm indication received from the remote
end.
.sp 1P
.LP
4.6.2
	\fIConsequent actions associated with stream Z\fR 
.sp 9p
.RT
.PP
Upon detection of 1544 kbit/s fault conditions in stream\ Z,
appropriate actions should be taken which are in accordance with \(sc\ 3.2 of
Recommendation\ G.733. In addition, the following consequent actions should 
be taken as indicated in Table\ 3/G.762: 
.RT
.LP
	i)
	declare a 1544 kbit/s alarm on the receive side of port\ Z;
.LP
	ii)
	send a 1544 kbit/s alarm indication to the remote end on
the send side of port\ Z in accordance with \(sc\ 4.2.4 of
Recommendation\ G.733;
.LP
	iii)
	send a 1544 kbit/s alarm indication signal (AIS) on the
receive side of streams\ X and\ Y. The AIS consists of an all\(hy1s
signal in all channels including the framing bit;
.LP
	iv)
	declare 1544 kbit/s AIS on the receive side of port Z;
.LP
	v)
	declare a remote 1544 kbit/s alarm on the receive side of
port\ Z;
.LP
	vi)
	send a 1544 kbit/s alarm indication to the remote end on
the receive side of streams\ X and\ Y in accordance with \(sc\ 4.2.4
of Recommendation\ G.733.
.bp
.ce
\fBH.T. [T3.762]\fR 
.ce
TABLE\ 3/G.762
.ce
\fB1544 kbit/s fault conditions associated with stream Z \fR 
.ce
\fBand consequent actions\fR 
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
lw(48p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) .
 {
Consequent 
actions
Fault conditions 
 }	 {
Declare 1544\ kbit/s alarm on Z
 }	 {
Send 1544\ kbit/s alarm indication to remote end
on Z
 }	 {
Send 1544\ kbit/s AIS on
X and Y
 }	Declare 1544\ kbit/s AIS on Z	 {
Declare remote 1544\ kbit/s alarm on Z
 }	 {
Send 1544\ kbit/s alarm indication to remote end on X
and Y 
 }
_
.T&
lw(48p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) .
 {
Loss of incoming signal at 1544 kbit/s
 }	Yes	Yes	Yes 			
_
.T&
lw(48p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) .
 {
Loss of 1544 kbit/s frame alignment
 }	Yes	Yes	Yes 			
_
.T&
lw(48p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) .
1544 kbit/s AIS received		Yes	Yes	Yes 		
_
.T&
lw(48p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) .
 {
1544 kbit/s alarm indication received from remote
end
 }					Yes	Yes 
_
.TE
.nr PS 9
.RT
.ad r
\fBTable 3/G.762 [T3.762], p.\fR 
.sp 1P
.RT
.ad b
.RT
.sp 1P
.LP
4.6.3
	\fIFault conditions associated with the signalling grouping channel\fR 
.sp 9p
.RT
.PP
A summary of the signalling grouping channel fault conditions
associated with the receive side of stream\ Z and the consequent actions are
listed in Table\ 4/G.762.
.PP
The transcoder shall detect the following signalling grouping channel fault 
conditions associated with stream\ Z: 
.RT
.LP
	i)
	loss of signalling grouping channel multiframe alignment on
a single time slot grouping associated with port\ X or a single
time slot grouping associated with port\ Y;
.LP
	ii)
	loss of signalling grouping channel multiframe alignment on
both time slot groupings associated with port\ X or both time
slot groupings associated with port\ Y;
.LP
	iii)
	remote time slot grouping alarm indication (M\d1\u)
received from the remote end on a single time slot grouping
associated with port\ X or a single time slot grouping associated
with port\ Y;
.LP
	iv)
	remote time slot grouping alarm indication (M\d1\u) received
from the remote end on both time slot groupings associated with
port\ X or both time slot groupings associated with port\ Y;
.LP
	v)
	signalling grouping channel AIS (M\d2\u) received from the
remote end on a single time slot grouping associated with port\ X
or a single time slot grouping associated with port\ Y;
.LP
	vi)
	signalling grouping channel AIS (M\d2\u) received from the
remote end on both time slot groupings associated with port\ X or
both time slot groupings associated with port\ Y;
.LP
	vii)
	remote signalling grouping channel AIS (M\d3\u) received
from the remote end on a single time slot grouping associated
with port\ X or a single time slot grouping associated with
port\ Y;
.LP
	viii)
	remote signalling grouping channel AIS (M\d3\u) received
from the remote end on both time slot groupings associated with
port\ X or both time slot groupings associated with port\ Y.
.bp
.sp 1P
.LP
4.6.4
	\fIConsequent actions associated with the signalling grouping\fR 
\fIchannel\fR 
.sp 9p
.RT
.PP
Upon detection of signalling grouping channel fault conditions in stream\ 
Z, the following consequent actions shall be taken as indicated in 
Table\ 4/G.762:
.RT
.LP
	i)
	declare time slot grouping alarm on the associated time slot
grouping;
.LP
	ii)
	send a time slot grouping alarm indication to the remote
end by forcing the M\d1\ubit within the affected signalling
grouping channel to\ 1;
.LP
	iii)
	condition the data in the affected channels on the receive
side of streams\ X or\ Y to provide a signal that is compatible
with downstream equipment;
.LP
	iv)
	condition the channel\(hyassociated signalling bits in
affected channels on the receive side of streams\ X or\ Y to
provide a signal that is compatible with downstream equipment.
An example for most signalling types would be universal trunk
conditioning where the signalling bits should be forced to the
idle state for 2\ to 3\ seconds, and then conditioned to simulate
the channel seized condition;
.LP
	v)
	send a 1544 kbit/s AIS on the receive side of stream\ X (for
time slot groupings 1\ and\ 2) or stream\ Y (for time slot
groupings\ 3 and\ 4). The AIS consists of an all 1s signal in all
channels including the framing bit;
.LP
	vi)
	declare a remote time slot grouping alarm condition on the
associated time slot grouping to indicate the reception of a
remote time slot grouping alarm indication in the M\d1\ubit of
the affected signalling grouping channel;
.LP
	vii)
	send a 1544 kbit/s alarm indication to the remote end on
the receive side of stream\ X (for time slot groupings\ 1 and\ 2) \fR 
and stream\ Y (for time slot groupings\ 3 and\ 4);
.LP
	viii)
	declare a signalling grouping channel AIS condition on
the associated time slot grouping to indicate the reception of
a signalling grouping channel AIS indication in the M\d2\ubit of
the affected signalling grouping channel;
.LP
	ix)
	declare a remote signalling grouping channel AIS condition
on the associated time slot grouping to indicate the reception
of a remote signalling grouping channel AIS indication in the
M\d3\ubit of the affected signalling grouping channel.
.sp 1P
.LP
4.6.5
	\fIFault conditions associated with streams X and Y\fR 
.sp 9p
.RT
.PP
A summary of the fault conditions associated with the frames of
streams\ X and\ Y and the consequent actions are listed in Table\ 5/G.762.
.PP
The transcoder shall detect the following fault conditions associated with 
streams\ X and\ Y: 
.RT
.LP
	i)
	loss of incoming signals at 1544 kbit/s;
.LP
	ii)
	loss of 1544 kbit/s frame alignment;
.LP
	iii)
	1544 kbit/s AIS received from remote end;
.LP
	iv)
	1544 kbit/s alarm indication received from the remote
end.
.sp 1P
.LP
4.6.6
	\fIConsequent actions associated with streams X and Y\fR 
.sp 9p
.RT
.PP
Upon detection of the 1544 kbit/s fault conditions associated with streams 
X and Y, the following consequent actions shall be taken in 
Table\ 5/G.762:
.RT
.LP
	i)
	declare 1544 kbit/s alarm on the send side of port X and\ Y;
.LP
	ii)
	send a 1544 kbit/s alarm indication to the remote end on
the receive side of streams\ X and\ Y in accordance with \(sc\ 4.2.4
of Recommendation\ G.733;
.LP
	iii)
	send a signalling grouping channel AIS to the remote end
by forcing the M\d2\ubit within the affected signalling grouping
channel(s) to\ 1;
.LP
	iv)
	condition the affected channels on the send side of
stream\ Z to provide a signal in all channels that is compatible
with downstream equipment;
.LP
	v)
	declare 1544 kbit/s AIS on the send side of port X or\ Y;
.LP
	vi)
	declare remote 1544 kbit/s alarm on the send side of port\ X
or\ Y;
.LP
	vii)
	send a signalling grouping channel AIS to the remote en
\fR 
by forcing the M\d3\ubit within the affected signalling
grouping channel(s) to a\ 1.
.bp
.ce
\fBH.T. [1T4.762]\fR 
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(342p) .
TABLE\ 4/G.762
.T&
cw(342p) .
 {
\fBSignalling grouping channel fault conditions associated
with stream Z and consequent actions\fR
 }
.TE
.TS
center box;
lw(51p) | cw(35p) | cw(29p) | cw(35p) | cw(35p) | cw(29p) | cw(35p) | cw(29p) | cw(35p) | cw(29p) .
 {
Consequent
actions
Fault conditions
 }	 {
Declare time slot grouping alarm
 }	 {
Send time slot grouping alarm indication to remote end 
 }	 {
Condition affected channels on X or Y
 }	 {
Condition signalling in affected channels on X
or Y
 }	 {
Send 1544 kbit/s AIS
on X or Y
 }	 {
Declare remote time slot grouping alarm
 }	 {
Send 1544 kbit/s alarm indication to remote end on
X or Y
 }	 {
Declare signalling grouping channel AIS
 }	 {
Declare remote signalling grouping channel AIS 
 }
_
.T&
lw(51p) | cw(35p) | cw(29p) | cw(35p) | cw(35p) | cw(29p) | cw(35p) | cw(29p) | cw(35p) | cw(29p) .
 {
Loss of signalling grouping channel multiframe alignment (single time slot
grouping)
 }	Yes	Yes	Yes	Yes 					
_
.T&
lw(51p) | cw(35p) | cw(29p) | cw(35p) | cw(35p) | cw(29p) | cw(35p) | cw(29p) | cw(35p) | cw(29p) .
 {
Loss of signalling grouping channel multiframe alignment (time slot
grouping pair)
 }	Yes	Yes			Yes 				
_
.T&
lw(51p) | cw(35p) | cw(29p) | cw(35p) | cw(35p) | cw(29p) | cw(35p) | cw(29p) | cw(35p) | cw(29p) .
 {
Remote time slot grouping alarm indication received (single time slot
grouping)
 }			Yes	Yes		Yes 			
_
.T&
lw(51p) | cw(35p) | cw(29p) | cw(35p) | cw(35p) | cw(29p) | cw(35p) | cw(29p) | cw(35p) | cw(29p) .
 {
Remote time slot grouping alarm indication received (time slot grouping
pair)
 }						Yes	Yes 		
_
.TE
.nr PS 9
.RT
.ad r
\fBTableau 4/G.762 [1T4.762], p. 18 \ \ \ A L'ITALIENNE\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.ce
\fBH.T. [2T4.762]\fR 
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(342p) .
 {
TABLE\ 4/G.762 \fI(cont.)\fR
 }
.TE
.TS
center box;
lw(51p) | cw(35p) | cw(29p) | cw(35p) | cw(35p) | cw(29p) | cw(35p) | cw(29p) | cw(35p) | cw(29p) .
 {
Consequent
actions
Fault conditions
 }	 {
Declare time slot grouping alarm
 }	 {
Send time slot grouping alarm indication to remote end 
 }	 {
Condition affected channels on X or Y
 }	 {
Condition signalling in affected channels on X
or Y
 }	 {
Send 1544 kbit/s AIS on X or Y
 }	 {
Declare remote time slot grouping alarm
 }	 {
Send 1544 kbit/s alarm indication to remote end on
X or Y
 }	 {
Declare signalling grouping channel AIS
 }	 {
Declare remote signalling grouping channel AIS 
 }
_
.T&
lw(51p) | cw(35p) | cw(29p) | cw(35p) | cw(35p) | cw(29p) | cw(35p) | cw(29p) | cw(35p) | cw(29p) .
 {
Signalling grouping channel AIS received (single time slot grouping)
 }			Yes	Yes				Yes 	
_
.T&
lw(51p) | cw(35p) | cw(29p) | cw(35p) | cw(35p) | cw(29p) | cw(35p) | cw(29p) | cw(35p) | cw(29p) .
 {
Signalling grouping channel AIS received (time slot grouping pair)
 }					Yes			Yes 	
_
.T&
lw(51p) | cw(35p) | cw(29p) | cw(35p) | cw(35p) | cw(29p) | cw(35p) | cw(29p) | cw(35p) | cw(29p) .
 {
Remote signalling grouping channel AIS received (single time slot
grouping)
 }			Yes	Yes					Yes 
_
.T&
lw(51p) | cw(35p) | cw(29p) | cw(35p) | cw(35p) | cw(29p) | cw(35p) | cw(29p) | cw(35p) | cw(29p) .
 {
Remote signalling grouping channel AIS received (time slot grouping
pair)
 }							Yes		Yes 
_
.TE
.nr PS 9
.RT
.ad r
\fBTableau 4/G.762 [2T4.762], p. 19 \ \ \ A L'ITALIENNE\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.ce
\fBH.T. [T5.762]\fR 
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(342p) .
TABLE\ 5/G.762
.T&
cw(342p) .
 {
\fB1544 kbit/s fault conditions associated with streams X and
Y and consequent actions\fR
 }
.TE
.TS
center box;
lw(60p) | cw(36p) | cw(36p) | cw(36p) | cw(36p) | cw(36p) | cw(36p) | cw(36p) .
 {
Consequent
actions
Fault conditions
 }	Declare 1544 kbit/s alarm	 {
Send 1544 kbit/s alarm indication to remote end
 }	 {
Send signalling grouping channel AIS
 }	 {
Condition affected channels in stream Z
 }	Declare 1544\ kbit/s AIS 	 {
Declare remote 1544 kbit/s alarm
 }	 {
Send signalling grouping channel AIS indication to
remote end 
 }
_
.T&
lw(60p) | cw(36p) | cw(36p) | cw(36p) | cw(36p) | cw(36p) | cw(36p) | cw(36p) .
 {
Loss of incoming signal at 1544 kbit/s
 }	Yes	Yes	Yes	Yes 			
_
.T&
lw(60p) | cw(36p) | cw(36p) | cw(36p) | cw(36p) | cw(36p) | cw(36p) | cw(36p) .
 {
Loss of 1544 kbit/s frame alignment
 }	Yes	Yes	Yes	Yes 			
_
.T&
lw(60p) | cw(36p) | cw(36p) | cw(36p) | cw(36p) | cw(36p) | cw(36p) | cw(36p) .
1544 kbit/s AIS received		Yes	Yes	Yes	Yes 		
_
.T&
lw(60p) | cw(36p) | cw(36p) | cw(36p) | cw(36p) | cw(36p) | cw(36p) | cw(36p) .
 {
1544 kbit/s alarm received from remote end
 }						Yes	Yes 
_
.TE
.nr PS 9
.RT
.ad r
\fBTableau 5/G.762 [T5.762], p. \ \ \ A L'ITALIENNE\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.sp 1P
.LP
4.7
	\fISynchronization\fR 
.sp 9p
.RT
.PP
It should be possible to currently synchronize the outgoing streams of 
ports\ X, Y and\ Z to any one of the following: 
.RT
.LP
	\(em
	timing signal associated with incoming PCM stream X;
.LP
	\(em
	timing signal associated with incoming PCM stream Y;
.LP
	\(em
	timing signal associated with incoming stream Z;
.LP
	\(em
	internal 1544 kbit/s timing signal.
.sp 1P
.LP
4.8
	\fIAbsolute delay\fR 
.sp 9p
.RT
.PP
The overall absolute delay introduced by a single transcoder in
either direction (PCM to ADPCM or ADPCM to PCM) should be no greater than
750\ microseconds for any of the 48\ channels.
.PP
When a 64kbit/s signal is transparently transferred through a single transcoder, 
the absolute delay introduced should be no greater than 
750\ microseconds in either direction. Frame integrity should be maintained 
for adjacent 64\ kbit/s channels (i.e.\ equal delay). 
.PP
In the case of channel associated signalling, the overall delay
introduced by a single transcoder should be no greater than
5.0\ milliseconds.
.RT
.sp 1P
.LP
4.9
	\fIJitter\fR 
.sp 9p
.RT
.PP
For further study.
.RT
.LP
.rs
.sp 33P
.sp 2P
.LP
\fBMONTAGE: RECOMMANDATION G.763 SUR LE RESTE DE CETTE PAGE\fR 
.sp 1P
.RT
.LP
.bp