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.nr LL 40.5P
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.rs
\v | 5i'
.LP
\fBMONTAGE:\ \fR REC.\ G.960 EN T\* | TE DE CETTE PAGE
.sp 2P
.LP
\v'25P'
\fBRecommendation\ G.961\fR 
.RT
.sp 2P
.ce 1000
\fBDIGITAL\ TRANSMISSION\ SYSTEM\ ON\ METALLIC\ LOCAL\fR 
.EF '%	Fascicle\ III.5\ \(em\ Rec.\ G.961''
.OF '''Fascicle\ III.5\ \(em\ Rec.\ G.961	%'
.ce 0
.sp 1P
.ce 1000
\fB LINES\ FOR\ ISDN\ BASIC\ RATE\ ACCESS\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
.sp 1P
.LP
1.1
	\fIScope\fR 
.sp 9p
.RT
.PP
This Recommendation covers the characteristics and parameters of a digital 
transmission system at the network side of the NT1 to form part of the 
digital section for the ISDN basic rate access. 
.PP
\fR The system will support the
.RT
.LP
	\(em
	full duplex;
.LP
	\(em
	bit sequence independent
.LP
transmission of two B\(hychannels and one D\(hychannel as defined in
Recommendation\ I.412 and the supplementary functions of the digital section
defined in Recommendation\ I.603 for operation and maintenance.
.PP
The terminology used in this Recommendation is very specific and not contained 
in the relevant terminology Recommendations. Therefore Annex\ B 
to Recommendation\ G.960 provides a number of terms and definitions used 
in this Recommendation. 
.bp
.sp 1P
.LP
1.2
	\fIDefinition\fR 
.sp 9p
.RT
.PP
Figure 1/G.961 shows the boundaries of the digital transmission
system in relation to the digital section.
.RT
.LP
.rs
.sp 17P
.ad r
\fBFigure 1/G.961, p.\fR 
.sp 1P
.RT
.ad b
.RT
.PP
The concept of the digital section is used in order to allow a
functional and procedural description and a definition of the network
requirements. Note that the reference points\ T and\ V\d1\uare not identical 
and therefore the digital section is not symmetric. 
.PP
The concept of a digital transmission system is used in order to
describe the characteristics of an implementation, using a specific medium, 
in support of the digital section. 
.RT
.sp 1P
.LP
1.3
	\fIObjectives\fR 
.sp 9p
.RT
.PP
Considering that the digital section between the local exchange and the 
customer is one key element of the successful introduction of ISDN into 
the network the following requirements for the specification have been 
taken into account: 
.RT
.LP
	\(em
	to meet the error performance specified in Recommendation
G.960;
.LP
	\(em
	to operate on existing 2\(hywire unloaded lines, open wires
being excluded;
.LP
	\(em
	the objective is to achieve 100% cable fill for ISDN basic
access without pair selection, cable rearrangements or removal of
bridged taps (BT) which exist in many networks;
.LP
\fR 
	\(em
	the objective to be able to extend ISDN basic access
provided services to the majority of customers without the use
of regenerators. In the remaining few cases special
arrangements may be required;
.LP
	\(em
	coexistence in the same cable unit with most of the existing
services like telephony and voice band data transmission;
.LP
	\(em
	various national regulations concerning EMI should be taken
into account;
.LP
	\(em
	power feeding from the network under normal or restricted
conditions via the basic access shall be provided where the
Administration provides this facility;
.LP
	\(em
	the capability to support maintenance functions shall be
provided.
.sp 1P
.LP
1.4
	\fIAbbreviations\fR 
.sp 9p
.RT
.PP
A number of abbreviations are used in this Recommendation. Some of them 
are commonly used in the ISDN reference configuration while others are 
created only for this Recommendation. The last one is given in the
following:
.RT
.LP
\fR 
	BER
	bit error ratio
.LP
	BT
	bridged tap
.LP
	CISPR
	Comit\*'e international sp\*'ecial de perturbation
radio\*'electrique (now part of IEC)
.LP
	CL
	control channel of the line system
.LP
	ECH
	echo cancellation
.bp
.LP
	EMI
	electro\(hymagnetic interference
.LP
	DLL
	digital local line
.LP
	DTS
	digital transmission system
.LP
	NEXT
	near\(hyend crosstalk
.LP
	PSL
	power sum loss
.LP
	TCM
	time compression multiplex
.LP
	UI
	unit interval
.sp 2P
.LP
\fB2\fR 	\fBFunctions\fR 
.sp 1P
.RT
.PP
Figure 2/G.961 shows the functions of the digital transmission
system on metallic local lines.
.RT
.LP
.rs
.sp 24P
.ad r
\fBFigure 2/G.961, p.\fR 
.sp 1P
.RT
.ad b
.RT
.sp 1P
.LP
2.1
	\fIB\(hychannel\fR 
.sp 9p
.RT
.PP
This function provides, for each direction of transmission, two
independent 64 kbit/s channels for use as B\(hychannels (as defined in
Recommendation\ I.412).
.RT
.sp 1P
.LP
2.2
	\fID\(hychannel\fR 
.sp 9p
.RT
.PP
This function provides, for each direction of transmission, one
D\(hychannel at a bit rate of 16\ kbit/s, (as defined in
Recommendation\ I.412).
.RT
.sp 1P
.LP
2.3
	\fIBit timing\fR 
.sp 9p
.RT
.PP
This function provides bit (signal element) timing to enable the
receiving equipment to recover information from the aggregate bit stream. 
Bit timing for the direction NT1 to LT shall be derived from the clock 
received by the NT1 from the LT. 
.RT
.sp 1P
.LP
2.4
	\fIOctet timing\fR 
.sp 9p
.RT
.PP
This function provides 8 kHz octet timing for the B\(hychannels. It
shall be derived from frame alignment.
.bp
.RT
.sp 1P
.LP
2.5
	\fIFrame alignment\fR 
.sp 9p
.RT
.PP
This function enables the NT1 and the LT to recover the time
division multiplexed channels.
.RT
.sp 1P
.LP
2.6
	\fIActivation from LT or NT1\fR 
.sp 9p
.RT
.PP
This function restores the Digital Transmission system (DTS)
between the LT and NT1 to its normal operational status. Procedures required
to implement this function are described in \(sc\ 6 of this
Recommendation.
.PP
Activation from the LT could apply to the DTS only or to the DTS
plus the customer equipment. In case the customer equipment is not connected, 
the DTS can still be activated. 
.PP
\fINote\fR \ \(em\ The functions required for operation and maintenance of
the NT1 and one regenerator (if required) and for some activationB/Fdeactivation 
procedures are combined in one transport capability to be transmitted along 
with the 2B\ +\ D\(hychannels. This transport capability is named the
CL\(hychannel.
.RT
.sp 1P
.LP
2.7
	\fIDeactivation\fR 
.sp 9p
.RT
.PP
This function is specified in order to permit the NT1 and the
regenerator (if it exists) to be placed in a low power consumption mode 
or to reduce intrasystem crosstalk to other systems. The procedures and 
exchange of information are described in \(sc\ 6 of this Recommendation. 
This 
deactivation should be initiated only by the exchange (ET). See Note in
\(sc\ 2.6.
.RT
.sp 1P
.LP
2.8
	\fIPower feeding\fR 
.sp 9p
.RT
.PP
This optional function provides for remote power feeding of one
regenerator (if required) and NT1. The provision of wetting current is
recommended.
.PP
\fINote\fR \ \(em\ The provision of line feed power to the user\(hynetwork
interface, normal or restricted power feeding as defined in
Recommendation\ I.430 is required by some Administrations.
.RT
.sp 1P
.LP
2.9
	\fIOperations and maintenance\fR 
.sp 9p
.RT
.PP
This function provides the recommended actions and information
described in Recommendation\ I.603.
.PP
The following categories of functions have been identified:
.RT
.LP
	\(em
	maintenance command (e.g., loopback control in the
regenerator or the NT1);
.LP
	\(em
	maintenance information (e.g., line errors);
.LP
	\(em
	indication of fault conditions;
.LP
	\(em
	information regarding power feeding in NT1.
.PP
See Note in \(sc\ 2.6.
.sp 2P
.LP
\fB3\fR 	\fBTransmission medium\fR 
.sp 1P
.RT
.sp 1P
.LP
3.1
	\fIDescription\fR 
.sp 9p
.RT
.PP
The transmission medium over which the digital transmission system is expected 
to operate, is the local line distribution network. 
.PP
A local line distribution network employs cables of pairs to provide services 
to customers. 
.PP
In a local line distribution network, customers are connected to the local 
exchange via local lines. 
.PP
A metallic local line is expected to be able to simultaneously carry bi\(hydirectional 
digital transmission providing ISDN basic access between LT and NT1. 
.PP
To simplify the provision of ISDN basic access, a digital transmission 
system must be capable of satisfactory operation over the majority of metallic 
local lines without requirement of any special conditioning. Maximum 
penetration of metallic local lines is obtained by keeping ISDN requirements 
at a minimum. 
.PP
In the following, the term Digital Local Line (DLL) is used to
describe a metallic local line that meets minimum ISDN requirements.
.RT
.sp 1P
.LP
3.2
	\fIMinimum ISDN requirements\fR \v'3p'
.sp 9p
.RT
.LP
	a)
	No loading coils;
.LP
	b)
	No open wires;
.LP
	c)
	When BTs are present, some restrictions may apply. Typical
allowable BT configurations are discussed in \(sc\ 4.2.1.
.bp
.sp 1P
.LP
3.3
	\fIDLL physical characteristics\fR 
.sp 9p
.RT
.PP
In addition to satisfying the minimum ISDN requirements, a DLL is typically 
constructed of one or more twisted\(hypair segments that are spliced 
together. In a typical local line distribution network, these twisted\(hypair
segments occur in different types of cables as described in
Figure\ 3/G.961.
.RT
.LP
.rs
.sp 11P
.ad r
\fBFigure 3/G.961, p.\fR 
.sp 1P
.RT
.ad b
.RT
.sp 2P
.LP
3.4
	\fIDLL electrical characteristics\fR 
.sp 1P
.RT
.sp 1P
.LP
3.4.1
	\fIInsertion loss\fR 
.sp 9p
.RT
.PP
The DLL will have non\(hylinear loss versus frequency characteristic. For 
any DLL of a particular gauge mix, with no BTs and with an insertion loss 
of \fIx\fR \ dB at 80\ kHz, the typical behaviour of its insertion loss 
versus 
frequency is depicted in Figure\ 4/G.961.
.RT
.LP
.rs
.sp 26P
.ad r
\fBFigure 4/G.961, p.\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.sp 1P
.LP
3.4.2
	\fIGroup delay\fR 
.sp 9p
.RT
.PP
Typical ranges of values of DLL group delay as a function of
frequency are shown in Figure\ 5/G.961.
.RT
.LP
.rs
.sp 32P
.ad r
\fBFigure 5/G.961, p.\fR 
.sp 1P
.RT
.ad b
.RT
.sp 1P
.LP
3.4.3
	\fICharacteristic impedance\fR 
.sp 9p
.RT
.PP
Typical ranges of values of the real and imaginary parts of the
characteristic impedance of twisted pairs in different types of cables are
shown in Figure\ 6/G.961.
.RT
.LP
.rs
.sp 8P
.LP
.bp
.LP
.rs
.sp 21P
.ad r
\fBFigure 6/G.961, p.6\fR 
.sp 1P
.RT
.ad b
.RT
.sp 1P
.LP
3.4.4
	\fINear\(hyend crosstalk (NEXT)\fR 
.sp 9p
.RT
.PP
The DLL will have finite crosstalk coupling loss to other pairs
sharing the same cable. Worst\(hycase NEXT power sum loss (PSL) varies 
from 44\ to 57\ dB at 80\ kHz (refer to \(sc\ 4.2.2). 
.PP
The DLL loss and PSL ranges have been independently specified.
However, it is not required that all points in both ranges be satisfied
simultaneously. A combined DLL loss/PSL representation is shown in
Figure\ 7/G.961 to define the combined range of operation.
.RT
.LP
.rs
.sp 21P
.ad r
\fBFigure 7/G.961, p.\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.sp 1P
.LP
3.4.5
	\fIUnbalance about earth\fR 
.sp 9p
.RT
.PP
The DLL will have finite balance about earth. Unbalance about earth is 
described in terms of longitudinal conversion loss. Worst\(hycase values 
are 
shown in Figure\ 8/G.961.
.RT
.LP
.rs
.sp 19P
.ad r
\fBFigure 8/G.961, p.\fR 
.sp 1P
.RT
.ad b
.RT
.sp 1P
.LP
3.4.6
	\fIImpulse noise\fR 
.sp 9p
.RT
.PP
The DLL will have impulse noise resulting from other systems
sharing the same cable as well as from other sources.
.RT
.sp 2P
.LP
\fB4\fR 	\fBSystem performance\fR 
.sp 1P
.RT
.sp 1P
.LP
4.1
	\fIPerformance requirements\fR 
.sp 9p
.RT
.PP
Performance limits for the digital section are specified in \(sc\ 4 of 
Recommendation\ G.960. The digital transmission system performance must 
be such that these performance limits are met. For that purpose, a digital 
transmission system is required to pass specific laboratory performance 
tests that are 
defined in the next sections.
.RT
.sp 1P
.LP
4.2
	\fIPerformance measurements\fR 
.sp 9p
.RT
.PP
Laboratory performance measurement of a particular digital
transmission system requires the following preparations:
.RT
.LP
	a)
	definition of a number of DLL models to represent physical
and electrical characteristics encountered in local line
distribution networks;
.LP
	b)
	simulation of the electrical environment caused by finite
crosstalk coupling loss to other pairs in the same cable;
.LP
\fR 
	c)
	simulation of the electrical environment caused by impulse
noise;
.LP
\fR 
	d)
	specification of laboratory performance tests to verify
that the performance limits referred to in \(sc\ 4.1 will be
met.
.sp 1P
.LP
4.2.1
	\fIDLL physical models\fR 
.sp 9p
.RT
.PP
For the purposes of laboratory testing of performance of a digital transmission 
system providing ISDN basic access, some models representative of DLLs 
to be encountered in a particular local line distribution network are 
required. The maximum loss in each model is optionally set between 37\ 
and 50\ dB at 80\ kHz to satisfy requirements of the particular network. 
Similarly, the 
lengths of BTs are optionally set within the range defined in
Figure\ 9/G.961.
.bp
.RT
.LP
.rs
.sp 39P
.ad r
\fBFigure 9.G.961, p.\fR 
.sp 1P
.RT
.ad b
.RT
.sp 2P
.LP
4.2.2
	\fIIntrasystem crosstalk modelling\fR 
.sp 1P
.RT
.sp 1P
.LP
4.2.2.1
	\fIDefinition of\fR \fBintrasystem crosstalk\fR 
.sp 9p
.RT
.PP
Crosstalk noise in general results due to finite coupling loss
between pairs sharing the same cable, especially those pairs that are
physically adjacent. Finite coupling loss between pairs causes a vestige 
of the signal flowing on one DLL (disturber DLL) to be coupled into an 
adjacent DLL 
(disturbed DLL). This vestige is known as crosstalk noise. Near\(hyend 
crosstalk (NEXT) is assumed to be the dominant type of crosstalk. Intrasystem 
NEXT or 
self NEXT results when all pairs interfering with each other in a cable 
carry the same digital transmission system. Intersystem NEXT results when 
pairs 
carrying different digital transmission systems interfere with each other.
Definition of intersystem NEXT is not part of this Recommendation.
.bp
.PP
\fR Intrasystem NEXT noise coupled into a disturbed DLL from a number of 
DLL disturbers is represented as being due to an equivalent single disturber 
DLL with a coupling loss versus frequency characteristic known as PSL.
Worst\(hycase PSL encountered in a local line distribution network is defined 
in Figure\ 10/G.961. All DLLs are assumed to have fixed resistance terminations 
of \fIRo\fR \ ohms. The range of\ \fIRo\fR is 110\ to 150\ ohms. 
.RT
.LP
.rs
.sp 17P
.ad r
\fBFigure 10/G.961, p.\fR 
.sp 1P
.RT
.ad b
.RT
.sp 1P
.LP
4.2.2.2
	\fIMeasurement arrangement\fR 
.sp 9p
.RT
.PP
Simulation of intrasystem NEXT noise is necessary for performance testing 
of digital transmission systems. Intrasystem noise coupled into the 
receiver of the disturbed DLL depends on:
.RT
.LP
	a)
	Power spectrum of the transmitted digital signal. The power
spectrum is a function of the line code and the transmit
filter.
.LP
	b)
	Spectrum shaping due to the PSL characteristic of
Figure\ 10/G.961.
.PP
The measurement arrangement of Figure 11/G.961 can be used for
testing of performance with intrasystem crosstalk noise.
.LP
.rs
.sp 16P
.ad r
\fBFigure 11/G.961, p.\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.PP
The measurement arrangement in Figure 11/G.961 is described in the following:
.LP
	a)
	Box 1 represents a white noise source of constant spectral
density. Spectrum is flat from 100\ Hz to 500\ kHz rolling off
afterwards at a rate \(>="\ 20\ dB/decade.
.LP
	b)
	Box 2 is a variable attenuator.
.LP
	c)
	Box 3 is a filter that shapes the power spectrum to
correspond to a particular line code and a particular transmit
filter.
.LP
	d)
	Box 4 is a filter that shapes the power spectrum according
to the PSL characteristic of Figure\ 10/G.961.
.LP
	e)
	Box 5 is a noise insertion circuit which couples the
simulated crosstalk noise into the DLL without disturbing its
performance. The insertion circuit therefore must be of
sufficiently high output impedance relative to the magnitude of
the characteristic impedance of the DLL under test. A value of
\(>="\ 4.0\ k?73 in the frequency range 0\ to 1000\ kHz is
recommended.
.PP
Boxes 3, 4 and 5 in Figure 11/G.961 are conceptual. Dependent on the particular 
realization, they could possibly be combined into one circuit. The measurement 
arrangement in Figure\ 11/G.961 is calibrated according to the following 
steps: 
.LP
	a)
	By terminating the output of Box 5 with a resistor of a
value of \fIRo\fR /2\ ohm, and measuring the true r.m.s.
(root\(hymean\(hysquare) voltage across it in a bandwidth extending
from 100\ Hz to over 500\ kHz. The power dissipated in the
\fIRo\fR /2 resistor is 3\ dB higher than the power coupled into the
receiver of the DLL under test.
.LP
	b)
	The shape of the noise spectrum measured across the \fIRo\fR /2
resistor should be within:
.LP
	\(em
	\(+- |  dB for values within 0 dB to 10 dB down from the
theoretical peak;
.LP
	\(em
	\(+- |  dB for values within 10 dB to 20 dB down from
the theoretical peak;
.LP
	for measurement purposes a resolution bandwidth of \(= 10\ kHz
is recommended.
.LP
\fR 	c)
	The peak factor of the noise voltage across the \fIRo\fR /2
resistor should be \(>="\ 4. This in turn fixes the dynamic range
requirements of the circuits used in the measurement
arrangement.
.PP
With the specified calibrated measurement arrangement, intrasystem crosstalk 
noise due to a worst\(hycase PSL can be injected into the DLL under test 
while monitoring its performance. The noise level can be increased or decreased 
to determine positive or negative performance margins. 
.sp 2P
.LP
4.2.3
	\fIImpulse noise modelling\fR 
.sp 1P
.RT
.sp 1P
.LP
4.2.3.1
	\fIDefinition of impulse noise\fR 
.sp 9p
.RT
.PP
Impulse noise energy appears concentrated in random short time
intervals during which it attains substantial levels. For the rest of the 
time impulse noise effects are negligible. 
.RT
.sp 1P
.LP
4.2.3.2
	\fIMeasurement arrangement\fR 
.sp 9p
.RT
.PP
Figure 12/G.961 shows a possible arrangement for impulse noise
testing.
.RT
.LP
.rs
.sp 13P
.ad r
\fBFigure 12/G.961, p.\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.PP
The impulse noise source in Figure 12/G.961 is for further study. Two possible 
classes of impulse noise signals are described in the 
following:
.LP
	\(em
	white noise of flat spectral density level of 5\(hy10
\(*mV/
@ sqrt { z } @  and a bandwidth > | \ times the Nyquist frequency
of the particular system. The peak factor of the noise must be
> | ;
.LP
\fR 	\(em
	a particular waveform, as represented in
Figure\ 13/G.961.
.LP
.rs
.sp 20P
.ad r
\fBFigure 13/G.961, p.\fR 
.sp 1P
.RT
.ad b
.RT
.sp 1P
.LP
4.2.4
	\fIPerformance tests\fR 
.sp 9p
.RT
.PP
Five types of tests are required to describe the overall
performance of a particular digital transmission system to qualify it for
operation over the local line distribution network modelled in this
Recommendation.
.RT
.sp 1P
.LP
4.2.4.1
	\fIDynamic range\fR 
.sp 9p
.RT
.PP
Dynamic range performance describes the ability of a particular
digital transmission system to operate with received signals varying in 
level over a wide range. DLL models\ 1 and\ 2 in Figure\ 9/G.961 have a 
loss varying 
from very low (0\ dB) to very high (37\(hy50\ dB at 80\ kHz).
.PP
When testing with DLL models 1 and 2 in Figure 9/G.961, no errors
should be observed in any 15\ minutes (provisional) measuring interval when
monitoring any B\(hychannel.
.PP
Specification of data sequences to be used for this measurement are
for further study.
.RT
.sp 1P
.LP
4.2.4.2
	\fIImmunity to echoes\fR 
.sp 9p
.RT
.PP
The remaining DLL models in Figure 9/G.961 are used to test
performance of digital transmission systems in the presence of BTs and/or
diameter changes.
.PP
In each model, no errors should be observed in any 15\ minutes
(provisional) measuring interval when monitoring any B\(hychannel.
.PP
Specification of data sequences to be used for this measurement are
for further study.
.bp
.RT
.sp 1P
.LP
4.2.4.3
	\fIIntrasystem crosstalk\fR 
.sp 9p
.RT
.PP
Using the crosstalk arrangement described in \(sc\ 4.2.2.2 with
simulated crosstalk noise injected in each DLL model in Figure\ 9/G.961 the
observed bit error ratio (BER) should be \(=\ 10\uD\dlF261\u6\d (provisional).
.PP
When BER measurements are performed in a B\(hychannel, a measuring
interval of at least 15\ minutes (provisional) is required.
.PP
In each DLL model, performance margins are determined. Definition of a 
minimum positive performance margin is left for further study. This is 
required to account for additional DLL loss due to splices, and environmental 
effects (e.g.\ temperature change). 
.PP
Specification of data sequences to be used for this measurement are
for further study.
.RT
.sp 1P
.LP
4.2.4.4
	\fIImpulse noise\fR 
.sp 9p
.RT
.PP
For further study.
.RT
.sp 1P
.LP
4.2.4.5
	\fILongitudinal voltages induced from power lines\fR 
.sp 9p
.RT
.PP
For further study.
.RT
.sp 2P
.LP
\fB5\fR 	\fBTransmission method\fR 
.sp 1P
.RT
.PP
The transmission system provides for duplex transmission on 2\(hywire metallic 
local lines. Duplex transmission shall be achieved through the use of ECHO 
CANCELLATION (ECH) or TIME COMPRESSION MULTIPLEX (TCM). With the 
.PP
ECH method, illustrated in Figure\ 14/G.961, the echo canceller produces a
replica of the echo of the transmitted signal that is subtracted from the 
total received signal. The echo is the result of imperfect balance of the 
hybrid and impedance discontinuities in the line. 
.PP
With the TCM or \*Qburst mode\*U method, illustrated in Figure\ 15/G.961, 
transmissions on the DLL are separated in time (bursts). Blocks of bits 
(bursts) are sent alternatively in each direction. Bursts are passed through
buffers at each transceiver terminal such that the bit stream at the input 
and output of the TCM transceiver terminal is continuous at the rate\ R. 
The bit 
rate on the line is required to be greater than 2R to provide for an idle
interval between bursts which is necessary to allow for the transmission 
delay and transmitter/receiver turn\(hyaround (switching of Sn and Se in 
Figure\ 15/G.961).
.RT
.LP
.rs
.sp 16P
.ad r
\fBFigure 14/G.961, p.\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.LP
.rs
.sp 16P
.ad r
\fBFigure 15/G.961, p.\fR 
.sp 1P
.RT
.ad b
.RT
.sp 2P
.LP
\fB6\fR 	\fBActivationB/Fdeactivation\fR 
.sp 1P
.RT
.sp 1P
.LP
6.1
	\fIGeneral\fR 
.sp 9p
.RT
.PP
The functional capabilities of the activation/deactivation
procedure are specified in Recommendation\ G.960. The transmission system has
to meet the requirements specified in Recommendation\ G.960. In particular, 
it has to make provision to convey the signals defined in Recommendation\ 
G.960 
which are required for the support of the procedures.
.RT
.sp 1P
.LP
6.2
	\fIPhysical representation of signals\fR 
.sp 9p
.RT
.PP
The signals used in the digital transmission system are system
dependent and can be found in Annex\ A and in the Appendices to this
Recommendation.
.RT
.sp 2P
.LP
\fB7\fR 	\fBOperation and maintenance\fR 
.sp 1P
.RT
.sp 1P
.LP
7.1
	\fIOperation and maintenance functions\fR 
.sp 9p
.RT
.PP
The operation and maintenance functions in the digital transmission system 
using metallic local lines for the ISDN basic rate access, are defined 
in Recommendation\ G.960. 
.RT
.sp 2P
.LP
7.2
	\fICL channel\fR 
.sp 1P
.RT
.sp 1P
.LP
7.2.1
	\fBCL channel\fR \fIdefinition\fR 
.sp 9p
.RT
.PP
\fR 
This channel is conveyed by the digital transmission system in
both directions between LT and NT1. It is used to transfer information
concerning operation, maintenance and activation/deactivation of the digital
transmission system and of the digital section.
.RT
.sp 1P
.LP
7.2.2
	\fICL channel requirements\fR 
.sp 9p
.RT
.PP
For further study.
.PP
The minimum number of functions (optional or mandatory) the CL channel 
should support is for further study. 
.bp
.RT
.sp 1P
.LP
7.3
	\fITransfer mode of operation and maintenance links\fR 
.sp 9p
.RT
.PP
For further study.
.RT
.sp 2P
.LP
\fB8\fR 	\fBPower feeding\fR 
.sp 1P
.RT
.sp 1P
.LP
8.1
	\fIGeneral\fR 
.sp 9p
.RT
.PP
This section deals with power feeding of the NT1, one regenerator (if required), 
and the provision of power to the user\(hynetwork interface 
according to Recommendation\ I.430 under normal and restricted conditions.
.PP
\fR When activation/deactivation procedures are applied, power down
modes at the NT1, regenerator (if required) and the LT are defined.
.RT
.sp 1P
.LP
8.2
	\fIPower feeding options\fR 
.sp 9p
.RT
.PP
Power feeding options under normal and restricted conditions are
considered. For this purpose, a restricted condition is entered after failure 
of AC mains power at the NT1 location. 
.RT
.LP
	a)
	Power feeding of NT1 under normal conditions will be
provided using one of the following options:
.LP
	\(em
	AC mains powering;
.LP
	\(em
	remote powering from the network (or via a regenerator,
if required).
.LP
	In both cases the NT1 may provide power to the user\(hynetwork
interface according to Recommendation\ I.430. This power is
derived from AC mains or remotely from the network.
.LP
\fR 	b)
	Power feeding of NT1 under restricted conditions, when
provided, employs one of the following optional sources:
.LP
\fR 
	\(em
	back\(hyup battery;
.LP
	\(em
	remote powering from the network (or via a
regenerator, if required).
.LP
	In both cases the NT1 may provide power to the user\(hynetwork
interface according to Recommendation\ I.430.
.PP
Power feeding options are chosen to satisfy national
regulations.
.sp 1P
.LP
8.3
	\fIPower feeding and recovery methods\fR 
.sp 9p
.RT
.PP
Two power feeding and recovery methods are possible and are
described in Figure\ 16/G.961.
.RT
.LP
.rs
.sp 17P
.ad r
\fBFigure 16/G.961, p.\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.PP
When no regenerator is present on the DLL connecting the LT and
the NT1, for each case in Figure\ 16/G.961 the power source could be either a
constant voltage source with current limiting or a constant current source 
with voltage limiting. 
.PP
When a regenerator is present, both methods of power feeding and
recovery in Figure\ 16/G.961 remain applicable. However, when a constant
voltage source is used at the LT, the regenerator power sink is connected in
parallel to the DLLs and when a constant current source is used at the 
LT, the regenerator power sink is connected in series with the DLLs. The 
resulting 
configurations are shown in Figure\ 17/G.961.
.RT
.LP
.rs
.sp 28P
.ad r
\fBFigure 17/G.961, p.\fR 
.sp 1P
.RT
.ad b
.RT
.sp 1P
.LP
8.4
	\fIDLL resistance\fR 
.sp 9p
.RT
.PP
This parameter is a particular subject of the individual local
network and therefore out of the scope of this Recommendation. Its maximum
value depends on the LT output voltage, the power consumption of the NT1 and
regenerator (if required) and the power feeding arrangement for the
user\(hynetwork interface.
.RT
.sp 1P
.LP
8.5
	\fIWetting current\fR 
.sp 9p
.RT
.PP
The NT1 shall provide a DC termination to allow a minimum wetting current 
to flow (the value has to be defined) including the power down mode or 
in case of local power feeding of the NT1. 
.RT
.sp 1P
.LP
8.6
	\fILT aspects\fR 
.sp 9p
.RT
.PP
A current limitation for voltage source configuration or a voltage limitation 
for current source configuration is required. The values shall take into 
account the relevant IEC Publications and national safety 
regulations.
.PP
Short\(hyterm overload of the feeding current may be tolerated
(charging condition of the capacitor of DC/DC converter in NT1).
.bp
.RT
.sp 2P
.LP
8.7
	\fIPower requirements of NT1 and regenerator\fR 
.sp 1P
.RT
.sp 1P
.LP
8.7.1
	\fIPower requirements of NT1\fR \v'3p'
.sp 9p
.RT
.LP
	a)
	active state without powering of user\(hynetwork interface: to
be defined;
.LP
	b)
	active state including restricted powering of the
user\(hynetwork interface as defined in Recommendation\ I.430: to be
defined;
.LP
	c)
	active state including normal powering of user\(hynetwork
interface as defined in Recommendation\ I.430: to be defined;
.LP
\fR 
	d)
	power down mode: to be defined.
.sp 1P
.LP
8.7.2
	\fIPower requirements of regenerator\fR 
.sp 9p
.RT
.PP
For further study.
.RT
.sp 1P
.LP
8.8
	\fICurrent transient limitation\fR 
.sp 9p
.RT
.PP
The rate of change of current drawn by the NT1 or regenerator from the 
network shall not exceed \fIX\fR \ mA/\(*ms. The value of\ \fIX\fR is to 
be 
defined.
.RT
.sp 2P
.LP
\fB9\fR 	\fBEnvironmental conditions\fR 
.sp 1P
.RT
.sp 1P
.LP
9.1
	\fIClimatic conditions\fR 
.sp 9p
.RT
.PP
Climatograms applicable to the operation of NT1 and LT equipment in weather 
protected and non\(hyweather protected locations can be found in 
IEC\ Publication\ 721\(hy3. The choice of classes is under national
responsibility.
.RT
.sp 2P
.LP
9.2
	\fIProtection\fR 
.sp 1P
.RT
.sp 1P
.LP
9.2.1
	\fIIsolation\fR 
.sp 9p
.RT
.PP
Isolation between various points at the NT1 can be
identified:
.RT
.LP
	\(em
	between line interface and T reference point;
.LP
	\(em
	between line interface or T reference point and AC mains
(this is generally defined in IEC Guide\ 105 and IEC
Publication\ 950 but the test requirements may be different in
various countries);
.LP
	\(em
	between line interface and the protective ground of AC
mains.
.sp 1P
.LP
9.2.2
	\fIOvervoltage protection\fR \v'3p'
.sp 9p
.RT
.LP
	\(em
	To conform with Recommendations K.12, K.20 for LT.
.LP
\fR 	\(em
	To conform with Recommendations K.12, K.21 for NT1.
.sp 2P
.LP
9.3
	\fIElectromagnetic compatibility\fR 
.sp 1P
.RT
.sp 1P
.LP
9.3.1
	\fISusceptibility, radiated and conducted emission levels for LT\fR 
\fIor NT1 equipment\fR 
.sp 9p
.RT
.PP
This is outside of the scope of this Recommendation. CISPR
Publication\ 22 and national regulations have to be considered.
.RT
.sp 1P
.LP
9.3.2
	\fILimitation of the output power to the line\fR 
.sp 9p
.RT
.PP
Due to limited longitudinal conversion loss of the line at high
frequencies and the limitation of radiation according to CISPR Publication\ 
22 and national regulations, the output power shall be limited. The specific 
values are outside the scope of this Recommendation.
.bp
.RT
.ce 1000
ANNEX\ A
.ce 0
.ce 1000
(to Recommendation G.961)
.sp 9p
.RT
.ce 0
.ce 1000
\fBGeneral structure for an Appendix on electrical characteristics\fR 
.sp 1P
.RT
.ce 0
.LP
A.0
	\fIElectrical characteristics\fR 
.sp 1P
.RT
.PP
Short general characterization of the digital transmission
system.
.PP
\fINote\fR \ \(em\ The content of this Annex is a guideline for the
presentation of the description of the digital transmission systems and 
is not intended to constrain any of the systems which will be included. 
.RT
.sp 1P
.LP
A.1
	\fILine code\fR 
.sp 9p
.RT
.PP
For both directions of the transmission the line code is . |  | 
And the coding scheme will be\ . |  | 
.RT
.sp 1P
.LP
A.2
	\fISymbol rate\fR 
.sp 9p
.RT
.PP
The symbol rate is determined by the line code, the bit rate of the information 
stream and the frame structure. The symbol rate is 
. |  | \ kbaud.
.RT
.sp 2P
.LP
A.2.1
	\fIClock requirements\fR 
.sp 1P
.RT
.sp 1P
.LP
A.2.1.1
	\fINT1 free running clock accuracy\fR 
.sp 9p
.RT
.PP
The accuracy of the free running clock in the NT1 shall
be \(+- |  |  | \ ppm.
.RT
.sp 1P
.LP
A.2.1.2
	\fILT clock tolerance\fR 
.sp 9p
.RT
.PP
The NT1 and LT shall accept a clock accuracy from the ET
of \(+- |  |  | \ ppm.
.RT
.sp 1P
.LP
A.3
	\fIFrame structure\fR 
.sp 9p
.RT
.PP
The frame structure contains a frame word, \fIN\fR times (2B\ +\ D) and 
a CL channel. 
.RT
.ce
\fBH.T. [T1.961]\fR 
.ce

.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(48p) | cw(48p) | cw(48p) .
Frame word	\fIN\fR  times (2B + D)	CL channel
_
.TE
.nr PS 9
.RT
.ad r
\fBTable [T1.961], p.\fR 
.sp 1P
.RT
.ad b
.RT
.sp 1P
.LP
A.3.1
	\fIFrame length\fR 
.sp 9p
.RT
.PP
The number \fIN\fR of (2B\ +\ D) slots in one frame is . |  | 
.RT
.sp 1P
.LP
A.3.2
	\fIBit allocation in direction LT\(hyNT1\fR 
.sp 9p
.RT
.PP
In Figure A\(hy1/G.931 the bit allocation is given.
.RT
.ce
\fBH.T. [T2.961]\fR 
.ce
\fBTO BE PREPARED FOR EVERY SPECIFIC CASE\fR 
.ce
FIGURE\ A\(hy1/G.961
.ce
\fBBit allocation in direction LT\(hyNT1\fR 
.ce
\fBH.T. [T3.961]\fR 
.ce
\fBTO BE PREPARED FOR EVERY SPECIFIC CASE\fR 
.ce
FIGURE\ A\(hy2/G.961
.ce
\fBBit allocation in direction NT1\(hyLT\fR 
.ce

.ce
\fBH.T. [T4.961]\fR 
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
lw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) .
	S1	S2	S3	S4
.T&
cw(30p) | rw(30p) | rw(30p) | rw(30p) | rw(30p) .
0001	 | |  | | (em |  | 	 | |  | | (em |  | 	 | |  | | (em |  | 	 | |  | | (em |  | 
.T&
cw(30p) | rw(30p) | rw(30p) | rw(30p) | rw(30p) .
0111	\(em | |  | |  | 	\(em | |  | |  | 	\(em | |  | |  | 	\(em | |  | |  | 
.T&
cw(30p) | rw(30p) | rw(30p) | rw(30p) | rw(30p) .
0100	\(em |  | |  | | 	\(em |  | |  | | 	\(em |  | |  | | 	\(em |  | |  | | 
.T&
cw(30p) | rw(30p) | rw(30p) | rw(30p) | rw(30p) .
0010	+ | (em | |  | | 	+ | (em | |  | | 	+ | (em | |  | | 	+ | (em | |  | | 
.T&
cw(30p) | rw(30p) | rw(30p) | rw(30p) | rw(30p) .
1011	+ | |  | | (em | 	+ | |  | | (em | 	+ | |  | | (em | 	+ | |  | | (em | 
.T&
cw(30p) | rw(30p) | rw(30p) | rw(30p) | rw(30p) .
1110	 | |  | |  | (em | 	 | |  | |  | (em | 	 | |  | |  | (em | 	 | |  | |  | (em | 
.T&
cw(30p) | rw(30p) | rw(30p) | rw(30p) | rw(30p) .
1001	+ | (em |  | 	+ | (em |  | 	+ | (em |  | 	\(em | (em | (em | 
.T&
cw(30p) | rw(30p) | rw(30p) | rw(30p) | rw(30p) .
0011	 |  | | |  | |  | 	 |  | | |  | |  | 	 |  | | |  | |  | 	\(em | (em | |  | | 
.T&
cw(30p) | rw(30p) | rw(30p) | rw(30p) | rw(30p) .
1101	 | |  | |  | |  | | 	 | |  | |  | |  | | 	 | |  | |  | |  | | 	\(em | |  | | (em | 
.T&
cw(30p) | rw(30p) | rw(30p) | rw(30p) | rw(30p) .
1000	+ | | |  | |  | | 	+ | | |  | |  | | 	+ | | |  | |  | | 	 | |  | | (em | (em | 
.T&
cw(30p) | rw(30p) | rw(30p) | rw(30p) | rw(30p) .
0110	\(em |  |  | 	\(em |  |  | 	\(em |  |  | 	\(em | (em |  | 
.T&
cw(30p) | rw(30p) | rw(30p) | rw(30p) | rw(30p) .
1010	+ |  | (em | 	+ |  | (em | 	+ | (em | (em | 	+ | (em | (em | 
.T&
cw(30p) | rw(30p) | rw(30p) | rw(30p) | rw(30p) .
1111	+ |  | |  | | 	 |  | | |  | | (em | 	 |  | | |  | | (em | 	 |  | | |  | | (em | 
.T&
cw(30p) | rw(30p) | rw(30p) | rw(30p) | rw(30p) .
0000	+ | |  | |  | 	 | |  | | (em | |  | | 	 | |  | | (em | |  | | 	 | |  | | (em | |  | | 
.T&
cw(30p) | rw(30p) | rw(30p) | rw(30p) | rw(30p) .
0101	 | |  | |  |  | 	\(em | | |  | |  | | 	\(em | | |  | |  | | 	\(em | | |  | |  | | 
.T&
cw(30p) | rw(30p) | rw(30p) | rw(30p) | rw(30p) .
1100	+ |  |  | 	\(em |  | (em | 	\(em |  | (em | 	\(em |  | (em | 
.TE
.LP
\fINote\fR
\ \(em\ A received ternary block 000 is decoded as binary 0000.
.LP
FIGURE\ I\(hy1/G.961
\fBMMS43\(hyCode\fR
 }
.TE
.nr PS 9
.RT
.ad r
\fBTable [T2.961], p.\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.sp 1P
.LP
A.3.3
	\fIBit allocation in direction NT1\(hyLT\fR 
.sp 9p
.RT
.PP
In Figure A\(hy2/G.961 the bit allocation is given.
.RT
.ce
\fBH.T. [T3.961]\fR 
.ce
\fBTO BE PREPARED FOR EVERY SPECIFIC CASE\fR 
.ce
FIGURE\ A\(hy2/G.961
.ce
\fBBit allocation in direction NT1\(hyLT\fR 
.ce

.ce
\fBH.T. [T4.961]\fR 
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
lw(30p) | cw(30p) | cw(30p) | cw(30p) | cw(30p) .
	S1	S2	S3	S4
.T&
cw(30p) | rw(30p) | rw(30p) | rw(30p) | rw(30p) .
0001	 | |  | | (em |  | 	 | |  | | (em |  | 	 | |  | | (em |  | 	 | |  | | (em |  | 
.T&
cw(30p) | rw(30p) | rw(30p) | rw(30p) | rw(30p) .
0111	\(em | |  | |  | 	\(em | |  | |  | 	\(em | |  | |  | 	\(em | |  | |  | 
.T&
cw(30p) | rw(30p) | rw(30p) | rw(30p) | rw(30p) .
0100	\(em |  | |  | | 	\(em |  | |  | | 	\(em |  | |  | | 	\(em |  | |  | | 
.T&
cw(30p) | rw(30p) | rw(30p) | rw(30p) | rw(30p) .
0010	+ | (em | |  | | 	+ | (em | |  | | 	+ | (em | |  | | 	+ | (em | |  | | 
.T&
cw(30p) | rw(30p) | rw(30p) | rw(30p) | rw(30p) .
1011	+ | |  | | (em | 	+ | |  | | (em | 	+ | |  | | (em | 	+ | |  | | (em | 
.T&
cw(30p) | rw(30p) | rw(30p) | rw(30p) | rw(30p) .
1110	 | |  | |  | (em | 	 | |  | |  | (em | 	 | |  | |  | (em | 	 | |  | |  | (em | 
.T&
cw(30p) | rw(30p) | rw(30p) | rw(30p) | rw(30p) .
1001	+ | (em |  | 	+ | (em |  | 	+ | (em |  | 	\(em | (em | (em | 
.T&
cw(30p) | rw(30p) | rw(30p) | rw(30p) | rw(30p) .
0011	 |  | | |  | |  | 	 |  | | |  | |  | 	 |  | | |  | |  | 	\(em | (em | |  | | 
.T&
cw(30p) | rw(30p) | rw(30p) | rw(30p) | rw(30p) .
1101	 | |  | |  | |  | | 	 | |  | |  | |  | | 	 | |  | |  | |  | | 	\(em | |  | | (em | 
.T&
cw(30p) | rw(30p) | rw(30p) | rw(30p) | rw(30p) .
1000	+ | | |  | |  | | 	+ | | |  | |  | | 	+ | | |  | |  | | 	 | |  | | (em | (em | 
.T&
cw(30p) | rw(30p) | rw(30p) | rw(30p) | rw(30p) .
0110	\(em |  |  | 	\(em |  |  | 	\(em |  |  | 	\(em | (em |  | 
.T&
cw(30p) | rw(30p) | rw(30p) | rw(30p) | rw(30p) .
1010	+ |  | (em | 	+ |  | (em | 	+ | (em | (em | 	+ | (em | (em | 
.T&
cw(30p) | rw(30p) | rw(30p) | rw(30p) | rw(30p) .
1111	+ |  | |  | | 	 |  | | |  | | (em | 	 |  | | |  | | (em | 	 |  | | |  | | (em | 
.T&
cw(30p) | rw(30p) | rw(30p) | rw(30p) | rw(30p) .
0000	+ | |  | |  | 	 | |  | | (em | |  | | 	 | |  | | (em | |  | | 	 | |  | | (em | |  | | 
.T&
cw(30p) | rw(30p) | rw(30p) | rw(30p) | rw(30p) .
0101	 | |  | |  |  | 	\(em | | |  | |  | | 	\(em | | |  | |  | | 	\(em | | |  | |  | | 
.T&
cw(30p) | rw(30p) | rw(30p) | rw(30p) | rw(30p) .
1100	+ |  |  | 	\(em |  | (em | 	\(em |  | (em | 	\(em |  | (em | 
.TE
.LP
\fINote\fR
\ \(em\ A received ternary block 000 is decoded as binary 0000.
.LP
FIGURE\ I\(hy1/G.961
\fBMMS43\(hyCode\fR
 }
.TE
.nr PS 9
.RT
.ad r
\fBTable [T3.961], p.\fR 
.sp 1P
.RT
.ad b
.RT
.sp 1P
.LP
A.4
	\fIFrame word\fR 
.sp 9p
.RT
.PP
The frame word is used to allocate bit positions to the 2B\ +\ D\ +\ CL 
channels. It may, however, also be used for other functions. 
.RT
.sp 1P
.LP
A.4.1
	\fIFrame word in direction LT\(hyNT1\fR 
.sp 9p
.RT
.PP
The code for the frame word will be . |  | 
.RT
.sp 1P
.LP
A.4.2
	\fIFrame word in direction NT1\(hyLT\fR 
.sp 9p
.RT
.PP
The code for the frame word will be . |  | 
.RT
.sp 1P
.LP
A.5
	\fIFrame alignment procedure\fR 
.sp 9p
.RT
.sp 1P
.LP
A.6
	\fIMultiframe\fR 
.sp 9p
.RT
.PP
To enable bit allocation of the CL channel in more frames next to each 
other a multiframe structure may be used. The start of the multiframe is 
determined by the frame word. The total number of frames in a multiframe 
is . |  | 
.RT
.sp 1P
.LP
A.6.1
	\fIMultiframe word in direction NT1\(hyLT\fR 
.sp 9p
.RT
.PP
The multiframe will be identified by . |  | 
.RT
.sp 1P
.LP
A.6.2
	\fIMultiframe word in direction LT\(hyNT1\fR 
.sp 9p
.RT
.PP
The multiframe will be identified by . |  | 
.RT
.sp 1P
.LP
A.7
	\fIFrame offset between LT\(hyNT1 and NT1\(hyLT frames\fR 
.sp 9p
.RT
.PP
The NT1 shall synchronize its frame on the frame received in the
direction LT to NT1 and will transmit its frame with an offset.
.RT
.sp 2P
.LP
A.8
	\fICL channel\fR 
.sp 1P
.RT
.sp 1P
.LP
A.8.1
	\fIBit rate\fR 
.sp 9p
.RT
.sp 1P
.LP
A.8.2
	\fIStructure\fR 
.sp 9p
.RT
.sp 1P
.LP
A.8.3
	\fIProtocols and procedures\fR 
.sp 9p
.RT
.sp 1P
.LP
A.9
	\fIScrambling\fR 
.sp 9p
.RT
.PP
Scrambling will be applied on 2B+D channels and the scrambling
algorithm shall be as follows:
.RT
.LP
\fR 
	\(em
	In direction LT to NT1
.LP
	\(em
	In direction NT1 to LT.
.bp
.sp 1P
.LP
A.10
	\fIActivation/deactivation\fR 
.sp 9p
.RT
.PP
Description of system activation/deactivation procedure including options 
that are supported and options that are not supported. 
.PP
See also Recommendation\ G.960, \(sc\ 5.
.RT
.sp 1P
.LP
A.10.1
	\fISignals used for activation\fR 
.sp 9p
.RT
.PP
A list and definition of the signals used for
activation/deactivation (SIGs).
.RT
.LP
	\(em
	signals used for start\(hyup (CL not available);
.LP
	\(em
	bits in CL channel in an already established frame.
.sp 1P
.LP
A.10.2
	\fIDefinition of internal timers\fR 
.sp 9p
.RT
.sp 1P
.LP
A.10.3
	 \fIDescription of the activation procedure\fR (based on arrow sequence 
for the error\(hyfree case) 
\v'3p'
.sp 9p
.RT
.LP
	\(em
	activation from the network side;
.LP
	\(em
	activation from the user side.
.sp 1P
.LP
A.10.4
	\fIState transition table NT1 as a function of INFOs, SIGs,\fR 
\fIinternal timers\fR 
.sp 9p
.RT
.PP
The description of loop backs and options supported is given in
such a way that the minimum implementation may be clearly identified.
.RT
.sp 1P
.LP
A.10.5
	\fIState transition table LT as a function of FEs, SIGs,\fR 
\fIinternal timers\fR 
.sp 9p
.RT
.PP
The description of loop backs and options supported is given in
such a way that the minimum implementation may be clearly identified.
.RT
.sp 1P
.LP
A.10.6
	\fIActivation times\fR 
.sp 9p
.RT
.PP
See Recommendation G.960, \(sc\(sc\ 5.5.1 and\ 5.5.2.
.RT
.sp 1P
.LP
A.11
	\fIJitter\fR 
.sp 9p
.RT
.PP
Jitter tolerances are intended to ensure that the limits of
Recommendation\ I.430 are supported by the jitter limits of the transmission
system on local lines. The jitter limits given below must be satisfied
regardless of the length of the local line and the inclusion of one
regenerator, provided that they are covered by the transmission media
characteristics (see \(sc\ 3). The limits must be met regardless of the bit
patterns in the\ B, D and CL channels.
.RT
.sp 1P
.LP
A.11.1
	\fINT1 input signal jitter tolerance\fR 
.sp 9p
.RT
.PP
The NT1 shall meet the performance objectives with wander/jitter at the 
maximum magnitudes (J\d1\u, J\d2\u) indicated in Figure\ A\(hy3/G.961, 
for single jitter frequencies in the range of F\d1\u\ Hz to F\d3\u\ kHz
(F\d3\u\ =\ 1/4\ F\d6\u, F\d6\u\ =\ 
symbol rate frequency), superimposed on the test signal source. The NT1 
shall also meet the performance objectives with wander per day of up to 
. |  |  UI peak\(hyto\(hypeak where the maximum rate of change of 
phase is . |  |  UI/hour.
.RT
.sp 1P
.LP
A.11.2
	\fINT1 output jitter limitations\fR 
.sp 9p
.RT
.PP
With the wander/jitter as specified in \(sc\ A.11.1 superimposed on the 
NT1 input signal, the jitter on the transmitted signal on the NT1 towards 
the network shall conform to the following: 
.RT
.LP
	a)
	The jitter shall be equal to or less than . |  |  UI
peak\(hyto\(hypeak and less than . |  |  UI r.m.s. when measured with a
high\(hypass filter having a 20\ dB/decade roll\(hyoff below
M | (mu | \d2\u\ Hz (M \(>="\ 1).
.LP
\fR 
	b)
	The jitter in the phase of the output signal relative to
the phase of the input signal (from the network) shall not
exceed . |  | \ UI peak\(hyto\(hypeak or . |  | \ UI r.m.s. when measured
with a band\(hypass filter having a 20\ dB/decade roll\(hyoff above
N | (mu | \d2\u\ Hz (N \(>="\ 2) and a 20\ dB/decade roll\(hyoff below
K | (mu | \dk\u(F\dk\u<
<\ 1). This requirement applies with
superimposed jitter in the phase of the input signal as specified
in \(sc\ A.11.1 for single frequencies up to F\d2\u\ Hz.
.bp
.sp 1P
.LP
A.11.3
	\fITest conditions for jitter measurements\fR 
.sp 9p
.RT
.PP
Due to bidirectional transmission on the 2\(hywire and due to severe intersymbol 
interference no well defined signal transitions are available at 
the NT1 2\(hywire point.
.RT
.LP
.rs
.sp 27P
.ad r
\fBFigure A\(hy3/G.961, p.\fR 
.sp 1P
.RT
.ad b
.RT
.sp 1P
.LP
A.12
	\fITransmitter output characteristics of NT1 and LT\fR 
.sp 9p
.RT
.PP
The following specifications apply with a load impedance
of . |  | 
.RT
.sp 1P
.LP
A.12.1
	\fIPulse amplitude\fR 
.sp 9p
.RT
.PP
The zero to peak nominal amplitude of the largest pulse shall be
. |  | \ V and the tolerance shall be \(+- |  |  | \ %.
.RT
.sp 1P
.LP
A.12.2
	\fIPulse shape\fR 
.sp 9p
.RT
.PP
The pulse shape shall meet the pulse mask of Figure . |  | 
.RT
.sp 1P
.LP
A.12.3
	\fISignal power\fR 
.sp 9p
.RT
.PP
The average signal power shall be between . |  |  dBm and
. |  |  dBm.
.RT
.sp 1P
.LP
A.12.4
	\fIPower spectrum\fR 
.sp 9p
.RT
.PP
The upper bound of the power spectral density shall be within the template 
in Figure . |  |  
.RT
.sp 1P
.LP
A.12.5
	\fITransmitter signal nonlinearity\fR 
.sp 9p
.RT
.PP
This is a measure of the deviations from ideal pulse heights and
the individual pulse nonlinearity.
.PP
The measurement method is for further study.
.bp
.RT
.sp 2P
.LP
A.13
	\fITransmitter/receiver termination\fR 
.sp 1P
.RT
.sp 1P
.LP
A.13.1
	\fIImpedance\fR 
.sp 9p
.RT
.PP
The nominal input/output impedance looking toward the NT1 or LT
respectively shall be . |  | 
.RT
.sp 1P
.LP
A.13.2
	\fIReturn loss\fR 
.sp 9p
.RT
.PP
The return loss of the impedance shall be greater than shown in the template 
Figure . |  |  
.RT
.sp 1P
.LP
A.13.3
	\fILongitudinal conversion loss\fR 
.sp 9p
.RT
.PP
The minimum longitudinal conversion loss shall be as
follows:
.RT
.LP
	. |  |  kHz\ \ . |  |  dB
.LP
	. |  |  kHz\ \ . |  |  dB
.ce 1000
APPENDIX\ 1
.ce 0
.ce 1000
(to Recommendation G.961)
.sp 9p
.RT
.ce 0
.ce 1000
\fBElectrical characteristics of an MMS 43 transmission system\fR 
.sp 1P
.RT
.ce 0
.LP
I.1
	\fILine code\fR 
.sp 1P
.RT
.PP
For each direction of transmission the line code is a Modified
Monitoring State Code mapping 4\ bits into 3\ ternary symbols with levels\ 
+,\ 0 
or\ \(em (MMS\ 43). Details of the coding scheme are given in Figure\ I\(hy1/G.961. 
Note that the numbers in the columns for each of the 4\ alphabets S1 . |  | \ 
S4 give 
the numbers of the alphabet to be used for the coding of the next block of
4\ bits. The bits and symbols standing left are those transmitted or received
first.
.RT
.LP
.rs
.sp 23P
.ad r
\fBFigure I\(hy1/G.961 [T4.961], p.\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.sp 1P
.LP
I.2
	\fISymbol rate\fR 
.sp 9p
.RT
.PP
The symbol rate is 120\ kbaud.
.RT
.sp 2P
.LP
I.2.1
	\fIClock symbol requirements\fR 
.sp 1P
.RT
.sp 1P
.LP
I.2.1.1
	\fINT1 free running clock accuracy\fR 
.sp 9p
.RT
.PP
The tolerance of the free running NT1 clock is \(+- | 00\ ppm.
.RT
.sp 1P
.LP
I.2.1.2
	\fILT clock tolerance\fR 
.sp 9p
.RT
.PP
The tolerance of the clock signal provided at the LT is
\(+- | \ ppm.
.RT
.sp 1P
.LP
I.3
	\fIFrame structure\fR 
.sp 9p
.RT
.PP
Each frame contains a frame word, 2B\ +\ D data and the CL\(hychannel. 
Multiframes are not used. 
.RT
.sp 1P
.LP
I.3.1
	\fIFrame length\fR 
.sp 9p
.RT
.PP
The length of each frame is 120 ternary symbols corresponding to
1\ ms. Each frame has 108\ symbols (corresponding to 144\ bits) carrying
2B\ +\ D data.
.RT
.sp 1P
.LP
I.3.2
	\fISymbol allocation LT to NT1\fR 
.sp 9p
.RT
.PP
In the direction LT to NT1 the 120 symbols of each frame are used   as follows:
.RT
.LP
	\(em
	Symbols 1 to 84:
	2B + D;
.LP
	\(em
	Symbol  85:
	CL\(hychannel;
.LP
	\(em
	Symbols 110 to 120:
	frame word.
.sp 1P
.LP
I.3.3
	\fISymbol allocation NT1 to LT\fR 
.sp 9p
.RT
.PP
In the direction NT1 to LT, the frame structure is identical to
that of the direction LT to NT1.
.PP
The frame transmitted by the NT1 is synchronized to that received from the LT.
.RT
.sp 2P
.LP
I.4
	\fIFrame word\fR 
.sp 1P
.RT
.sp 1P
.LP
I.4.1
	\fIFrame word in direction LT to NT1\fR 
.sp 9p
.RT
.PP
The frame word in the direction LT to NT1 is:
.PP
+ + + \(em \(em \(em + \(em \(em + \(em
.RT
.sp 1P
.LP
I.4.2
	\fIFrame word in direction NT1 to LT\fR 
.sp 9p
.RT
.PP
The frame word in the direction NT1 to LT is:
.PP
\(em + \(em \(em + \(em \(em \(em + + +
.RT
.sp 1P
.LP
I.5
	\fIFrame alignment procedure\fR 
.sp 9p
.RT
.PP
The transmission system is considered to be synchronous if the
frame word has been identified in the same position for 4\ immediately
succeeding frames. Loss of synchronization is assumed, if the detected frame
position does not coincide with the expected position during\ 60 . |  | 
200\ successive frames.
.RT
.sp 1P
.LP
I.6
	\fIMultiframe\fR 
.sp 9p
.RT
.PP
Not used.
.RT
.sp 1P
.LP
I.7
	\fIFrame offset at NT1\fR 
.sp 9p
.RT
.PP
On the line at the NT1 the frame word transmitted by the NT1 occurs 60 
\(+- | \ symbols (0.5\ ms) later than that received at the NT1 input, measured 
between the first symbols of each frame word.
.bp
.RT
.sp 2P
.LP
I.8
	\fICL\(hychannel\fR 
.sp 1P
.RT
.sp 1P
.LP
I.8.1
	\fIBit rate\fR 
.sp 9p
.RT
.PP
The bit rate for the CL\(hychannel (maintenance\(hychannel) is
1\ kbit/s.
.RT
.sp 1P
.LP
I.8.2
	\fIStructure\fR 
.sp 9p
.RT
.PP
No specific structure is defined for transparent messages.
.RT
.sp 1P
.LP
I.8.3
	\fIProtocols and procedures\fR 
.sp 9p
.RT
.PP
Transparent messages in the CL\(hychannel use \*Q0\*U and \*Q\(em\*U polarity 
of the CL\(hysymbol of the line signal. \*Q0\*U and \*Q+\*U polarity are 
used to request a 
loopback 2B\ +\ D in the NT1 or an intermediate repeater. Transparent use 
of the CL\(hychannel may override these loopback commands. 
.RT
.sp 1P
.LP
I.9
	\fIScrambling\fR 
.sp 9p
.RT
.PP
In order to minimize correlation between incoming and transmitted symbols 
scrambling is used. Scrambling is applied only to the 2B\ +\ D\(hychannels. 
.PP
The scrambling polynomial is different in both NT1 to LT and LT to NT1 
directions. 
.RT
.LP
	\(em
	In direction LT to NT1: 
	1 
\o'\(ci+' \fIx\fR \uD\dlF261\u5\d 
\o'\(ci+'
\fIx\fR \uD\dlF261\u2\d\u3\d
.LP
	\(em
	In direction NT1 to LT: 
	1 
\o'\(ci+' \fIx\fR \uD\dlF261\u1\d\u8\d 
\o'\(ci+'
\fIx\fR \uD\dlF261\u2\d\u3\d.
.LP
where 
\o'\(ci+' is the modulo two sum and \fIx\fR \uD\dlF261\fI\fI
\u\fIk\fR\dis the scrambled data delayed by \fIk\fR \ symbol intervals.
.sp 1P
.LP
I.10
	\fIActivation/deactivation\fR 
.sp 9p
.RT
.PP
Activation/deactivation is provided to enable the use of a power
down state especially for applications, where the NT1 is powered from the LT
via the local line. Activation from the power state may be initated from 
both ends usig a 7.5\ kHz burst signal. Collisions are handled through 
appropriate 
duration and repetition rate of these bursts.
.PP
The procedures on the line system support the procedures at reference point\ 
T for call control in accordance with Recommendation\ I.430 and the 
operation of loopbacks\ 1 (in the LT), 1A (in the regenerator) and\ 2 (in the
NT1) in accordance with Recommendation\ I.603. The loopbacks are transparent.
.PP
Timer 1 and timer 2, as defined in Recommendation\ I.430, are located as 
follows: 
.RT
.LP
	\(em
	Timer 1 in the ET layer 1 or the ET,
.LP
	\(em
	Timer 2 in the NT1.
.PP
The activation of the line system for maintenance purposes
e.g.\ error performance monitoring, is possible, even if no TE is connected 
to the interface at T\ reference point. 
.PP
Transmission of INFO 2 on the interface of T\ reference point is
initiated when the line system is synchronized in the direction LT to NT1.
.RT
.sp 1P
.LP
I.10.1
	\fISignals used for activation\fR 
.sp 9p
.RT
.PP
To provide means to control/indicate progress during
activation/deactivation across the local line the following signal elements 
are used: 
.RT
.LP
	SIG\ 0
	NT1 to LT and LT to NT1
.LP
	No signal.
.LP
	SIG\ 1W
	NT1 to LT
.LP
	Awake signal (7.5 kHz tone); signals the layer 1 entity
in the local exchange that it has to enter the power\(hyup
state and provide for the activation of the line system and
the interface at T\ reference point.
.LP
	This signal is also used
as awake acknowledge on the receipt of SIG\ 2W.
.LP
	SIG\ 2W
	LT to NT1
.LP
	Awake signal (7.5 kHz tone); signals the NT1 that it has
to enter the power\(hyup state and prepare for synchronization
on an incoming signal from the LT.
.LP
	This signal is also used as awake acknowledge on the
receipt of SIG 1W.
.bp
.LP
	SIG\ 1
	NT1 to LT
.LP
	Signal which contains framing information and allows
the synchronization of the receiver in the LT. It informs
the LT that the NT1 has synchronized on SIG\ 2.
.LP
	SIG\ 2
	LT to NT1
.LP
	Signal which contains framing information and allows the
synchronization of the receiver in the NT1.
.LP
	SIG\ 1A
	NT1 to LT
.LP
	Signal similar to SIG 1 but without framing information.
.LP
	SIG\ 3
	NT1 to LT
.LP
	Signal which contains framing information and allows the
synchronization of the receiver in the LT. It indicates to
the ET that the interface at T\ reference point is
synchronized in both directions of transmission (except in
the case of loopback\ 2 and 1A).
.LP
	SIG\ 4H
	LT to NT1
.LP
	Signal which requires the NT1 to establish full layer 1
information transfer capability in both directions of
transmission.
.LP
	SIG\ 4
	LT to NT1
.LP
	Signal which contains framing information and operational
data on\ B and D\ channels.
.LP
	SIG\ 5
	NT1 to LT
.LP
	Signal which contains framing information and operational
data on\ B and D\ channels.
.LP
	SIG\ 2\(hyL2
	LT to NT1
.LP
	Signal similar to SIG 2, but includes a loopback\ 2
request.
.LP
	SIG\ 4H\(hyL2
	LT to NT1
.LP
	Signal which requires the NT1 to operate loopback\ 2
and to establish layer\ 1 information transfer capability
in the direction LT to TE (transparent loopback\ 2).
.LP
	SIG\ 4\(hyL2
	Signal similar to SIG 4, but includes a loopback\ 2
request.
.PP
All SIGs, except SIG 1W and SIG 2W, are continuous signals. The
awake signals SIG\ 1W and SIG\ 2W are sent for a specified period of time 
only, but may be repeated if no acknowledgement is received. The repetition 
times are specified in a way to assure a proper interworking with the normal 
activation procedure. 
.PP
The loopback requests are transmitted making use of the CL channel.
All other SIGs do not require the CL channel.
.PP
The CL channel is provided with all SIGs except SIG\ 0, SIG\ 1W, SIG\ 2W 
and SIG\ 1A. 
.RT
.sp 1P
.LP
I.10.2
	\fIDefinition of internal timers\fR 
.sp 9p
.RT
.PP
In the state transition tables and arrow diagrams the following
internal timers are used:
.RT
.LP
	Tn1\ =
	13\ ms:
	timer to supervise repetition of the
awake signal SIG\ 2W from the LT
.LP
	Tl1\ =
	\ 7\ ms:
	timer to supervise repetition of the awake
signal SIG\ 1W from the NT1
.LP
	Tl2\ =
	\ 1\ ms:
	timer which defines the duration of SIG\ 4H
and SIG 4H\(hyL2
.LP
	Tl3\ =
	\ 1\ ms:
	timer which assures that, under non\(hyfailure
conditions, the PH\(hyAI is passed first in the
TE and then in the LT/ET. This protects the first
layer 2\ frame (layer\ 3 \(em\ SETUP message) from the
network side.
.LP
	Tl4\ =
	12\ ms:
	timer used to start transmission of SIG\ 2
when loopback\ 1 is requested.
.LP
	Tl5\ =
	\ 0.1 . |  |  1\ s:
	timer to supervise the
deactivation procedure (within ET).
.sp 1P
.LP
I.10.3
	\fIDescription of the activation procedure\fR 
.sp 9p
.RT
.PP
In Figure I\(hy2/G.961 the activation/deactivation procedures are
described for the non\(hyfailure situation.
.PP
Timer T1 (located in ET layer 1) and Timer T2 (located in NT1) are as specified 
in Recommendation\ I.430; the Functional Elements (FE) are defined in Recommendation\ 
G.960, \(sc\ 5.4.1.3, and the primitives in Recommendation\ G.960, 
\(sc\ 5.4.2.2 and \(sc\ 5.4.2.3.
.RT
.sp 1P
.LP
I.10.4
	\fINT1 state transition table\fR 
.sp 9p
.RT
.PP
The NT1 state transition table is described in Table\ I\(hy1/G.961.
INFOs on the interface at T\ reference point are related to SIGs on the line
system and vice versa.
.bp
.RT
.LP
.rs
.sp 47P
.ad r
\fBFigure I\(hy2/G.961, p.23\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.ce
\fBH.T. [1T5.961]\fR 
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(342p) .
TABLE\ I\(hy1/G.961
 {
\fBNT1 state transition table\fR
 }
.TE
.TS
center box ;
lw(36p) | lw(27p) | lw(27p) | lw(27p) | lw(21p) | lw(27p) | lw(27p) | lw(27p) | lw(21p) | lw(27p) | lw(27p) | lw(27p) | lw(21p) .
INFO 0	\(em	\(em	\(em	\(em	\(em	\(em	NT 1.9	NT 1.1	\(em	\(em	\(em	\(em
_
.T&
lw(36p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) .
INFO 1	NT 1.2	\(em	\(em	\(em	\(em	\(em	/	\(em	\(em	/	\(em	/
_
.T&
lw(36p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) .
INFO 3	/	/	/	/	NT 1.6	\(em	\(em	\(em	NT 1.7	/	\(em	\(em  
_
.T&
lw(36p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) .
SIG 0	\(em	\(em	\(em	ST.T2; NT 1.8	ST.T2; NT 1.8	ST.T2; NT 1.8	ST.T2; NT 1.8	\(em	ST.T2; NT 1.8	ST.T2; NT 1.8	ST.T2; NT 1.8	ST.T2; NT 1.8  
_
.T&
lw(36p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) .
SIG 2W	ST. TN1; NT 1.3	NT 1.4	/	/	/	/	/	\(em	/	/	/	/  
_
.T&
lw(36p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) .
SIG 2	/	\(em	\(em	NT 1.5	\(em	\(em	/	/	/	/	NT 1.6 or \(em	/
_
.T&
lw(36p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) .
SIG 4H	/	/	/	/	/	NT 1.7	\(em	/	/	/	NT 1.7	/
_
.T&
lw(36p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) .
SIG 4	/	/	/	/	/	/	\(em	/	\(em	\(em	/	NT 1.7
_
.T&
lw(36p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) .
Exp. of T2  (Note 1)	\(em	\(em	\(em	\(em	\(em	\(em	\(em	NT 1.1	\(em	\(em	\(em	\(em
_
.T&
lw(36p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) .
Lost framing T\ interface	/	/	/	/	/	\(em	NT 1.9	\(em	\(em	\(em	/	/
_
.T&
lw(36p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) .
Lost framing line system	/	/	/	/	NT 1.10	NT 1.10	NT 1.10	/	NT 1.10	\(em	NT 1.10	 {
NT 1.10
Exp. of internal timer Tn1
/
/
NT 1.4
/
/
/
/
/
/
/
/
/
 }
_
.TE
.nr PS 9
.RT
.ad r
\fBTableau I\(hy1/G.961 [1T5.961] A L'ITALIENNE, p.24\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.ce
\fBH.T. [2T5.961]\fR 
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(342p) .
 {
TABLE\ I\(hy1/G.961\fI(cont.)\fR
 }
.TE
.TS
center box;
lw(36p) | lw(27p) | lw(27p) | lw(27p) | lw(21p) | lw(27p) | lw(27p) | lw(27p) | lw(21p) | lw(27p) | lw(27p) | lw(27p) | lw(21p) .
												
.T&
lw(36p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) .
SIG 2\(hyL2	/	\(em	\(em	NT 2.1	NT 2.1 or \(em	NT 2.1 or \(em	/	/	/	/	\(em	/  
_
.T&
lw(36p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) .
SIG 4H\(hyL2	/	/	/	/	/	NT 2.2	\(em	/	/	/	NT 2.2	\(em
_
.T&
lw(36p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) .
SIG 4\(hyL2	/	/	/	/	/	/	NT 2.2	/	NT 2.2	NT 2.2	/	 {
\(em
\(em
No state change.
 }
.TE
.LP
/
Impossible by the definition of peer\(hyto\(hypeer physical layer procedures
or system internal reasons.
.LP
ST.Tx; NTy\ Start Timer x; enter state NT y.
.LP
\fINote\ 1\fR
\ \(em\ Timer T2 as defined in Recommendation I.430.
.LP
\fINote\ 2\fR
\ \(em\ INFO X: signal with no framing information i.e. binary
ZERO's.
.LP
\fINote\ 3\fR
\ \(em\ Any other signal which produces an error indication on the LT side is allowed, especially loss of framing or excessive error rate.
.LP
\fINote\ 4\fR
\ \(em\ The D\(hyEcho bit is set to binary ZERO.
.LP
\fINote\ 5\fR
\ \(em\ The B\(hy and D\(hychannels are looped back to the network side.
.nr PS 9
.RT
.ad r
\fBTableau I\(hy1/G.961 (SUITE) [2T5.961] A L'ITALIENNE, p.24\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.PP
The following states are used:
.LP
	NT\ 1.1
	Deactivated state (low power consumption mode). No
signal is transmitted.
.LP
	NT\ 1.2
	The NT1 sends the awake signal SIG 1W to the LT, on the
receipt of INFO\ 1 from the user side, and waits for the
receipt of the awake acknowledge signal SIG\ 2W from the LT.
.LP
	NT\ 1.3
	On receipt of the awake signal SIG 2W, the NT1 responds
with SIG\ 1W and starts transmission of SIG\ 1A on expiry of
timer\ Tn1, unless a new awake signal SIG\ 2W from the LT is
received.
.LP
	NT\ 1.4
	After completion of the awake procedure, the NT1
waits for SIG\ 2 to synchronize its receiver.
.LP
	NT\ 1.5
	The receiver on the network side is synchronized. The
NT1 sends SIG\ 1 to the LT and INFO\ 2 to the user side to
initiate the activation of the interface of reference
point\ T. It waits for the receipt of INFO\ 3.
.LP
	NT\ 1.6
	The interface at T\ reference point is synchronized in
both directions of transmission. The NT1 sends SIG\ 3 to the
LT and waits for the receipt of SIG\ 4H.
.LP
	NT\ 1.7
	The NT1 is fully active and sends INFO 4 to the user
side and SIG\ 5 to the LT. The\ B and D\ channels are
operational.
.LP
	NT\ 1.8
	Pending deactivation state. The NT1 sends INFO\ 0 to the
user side to deactivate the interface at reference point\ T
and SIG\ 0 to the LT. It waits for the receipt of INFO\ 0 or
expiry of timer\ T2 to enter state NT1.1.
.LP
	NT\ 1.9
	This state is entered on loss of signal or loss of
framing at the T\ interface. No indication is sent to the LT,
in accordance with Note\ 3 to Table\ 4/I.430.
.LP
	NT\ 1.10
	This state is entered on loss of framing at the line
side. An indication is forwarded to the user side (INFO\ X)
and to the network side (SIG\ 0).
.PP
The following states support activation when loopback\ 2 is
requested:
.LP
	NT\ 2.1
	The receiver on the network side is synchronized. The
NT1 sends SIG\ 3 to the LT and INFO\ 2 to the user side
(transparent loopback). It waits for the receipt of
SIG\ 4H\(hyL2 from the LT.
.LP
	NT\ 2.2
	The NT1 is fully active and sends INFO\ 4 to the user
side (transparent loopback) and SIG\ 5 to the LT. Loopback\ 2
is operated and receive data 2B\ +\ D are sent to the
LT.
.sp 1P
.LP
I.10.5
	\fILT state transition table\fR 
.sp 9p
.RT
.PP
The LT state transition table is described in Table\ I\(hy2/G.961. SIGs 
on the line sysem are related to Functional Elements (FEs) on the V\d1\ureference 
point. 
.RT
.PP
The following states are used:
.LP
	LT\ 1.1
	Deactivated state. No signal is transmitted.
.LP
	LT\ 1.2
	On receipt of the awake signal SIG 1W, the LT responds
with SIG\ 2W and starts transmission of SIG\ 2 on expiry of
timer\ Tl1, unless a new awake signal SIG\ 1W from the NT1 is
received.
.LP
	LT\ 1.3
	The LT sends the awake signal SIG 2W to the NT1, on the
receipt of FE\ 1, and waits for the awake acknowledge signal
SIG\ 1W from the NT1.
.LP
	LT\ 1.4
	The LT sends SIG 2 to the NT1 and waits for SIG\ 1 or
SIG\ 3 to synchronize its receiver. When the LT is
synchronized and has detected SIG\ 1, it issues FE\ 3.
.LP
	LT\ 1.5
	The line transmission system is synchronized in both
directions of transmission. The LT waits for the receipt of
SIG\ 3.
.LP
	LT\ 1.6
	The line transmission system and the interface at
T\ reference point are synchronized in both directions of
transmission. The LT sends SIG\ 4H until the expiry of
timer\ Tl2.
.LP
	LT\ 1.7
	Fully active state. The LT sends SIG\ 4 to the NT1 and
issues FE\ 4. The\ B and D\ channels are fully operational.
.LP
	LT\ 1.8
	Pending deactivation state. The LT sends SIG\ 0 to the
NT1 to deactivate the line system and the interface at
T\ reference point. It waits for the receipt of SIG\ 0 to
enter state\ LT\ 1.1 and to issue FE\ 6.
.bp
.LP
.ce
\fBH.T. [1T6.961]\fR 
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(342p) .
TABLE\ I\(hy2/G.961
.T&
cw(342p) .
 {
\fBLT state transition table\fR
 }
.TE
.TS
center box;
cw(36p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) .
State	LT 1.1	LT 1.2	LT 1.3	LT 1.4	LT 1.5	LT 1.6	LT 1.7	LT 1.8	LT 2.1	LT 2.2	LT 2.3	LT 2.4
_
.T&
lw(36p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) .
 {
Transmit
signal 
Receive
signal
 }	SIG 0	SIG 2W	SIG 2W	SIG 2	SIG 2	SIG 4H	SIG 4	SIG 0	SIG 2W	SIG 2	SIG 4H	SIG 4
_
.T&
lw(36p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) .
FE 1	LT 1.3	\(em	\(em	\(em	\(em	\(em	\(em	\(em	\(em	\(em	\(em	\(em
_
.T&
lw(36p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) .
FE 5	:	LT 1.8	LT 1.8	LT 1.8	LT 1.8	LT 1.8	LT 1.8	\(em	LT 1.8	LT 1.8	LT 1.8	LT 1.8 
_
.T&
lw(36p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) .
SIG 0	\(em	\(em	\(em	\(em	FE 7;  \(em	FE 7;  \(em	FE 7;  \(em	FE 6;  LT 1.1	\(em	\(em	\(em	\(em
_
.T&
lw(36p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) .
SIG 1W	ST.Tl1,  FE 2;  LT 1.2	:	LT 1.4	/	/	/	/	\(em	\(em	/	/	/
_
.T&
lw(36p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) .
SIG 1	/	/	/	FE 3;  LT 1.5	\(em	/	/	\(em	/	\(em	\(em	\(em
_
.T&
lw(36p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) .
SIG 3	/	/	/	ST.Tl2;  LT 1.6	ST.Tl2;  LT 1.6	\(em	\(em	\(em	/	\(em	\(em	\(em
_
.T&
lw(36p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) .
Exp. of intern. timer\ T11	\(em	LT 1.4	\(em	\(em	\(em	\(em	\(em	\(em	\(em	\(em	\(em	\(em
_
.T&
lw(36p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) .
Exp. of intern. timer\ T12	\(em	\(em	\(em	\(em	\(em	FE 7;  LT 1.4	\(em	\(em	\(em	\(em	FE 4;  LT 2.4	 {
\(em
Lost framing line system
/
/
/
/
FE 7;
\(em
FE 7;
\(em
FE 7;
\(em
\(em
/
/
/
/
 }
_
.TE
.nr PS 9
.RT
.ad r
\fBTableau I\(hy1/G.961 [1T6.961] A L'ITALIENNE, p.24\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.ce
\fBH.T. [2T6.961]\fR 
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(342p) .
TABLE\ I\(hy2/G.961
.TE
.TS
center box;
cw(36p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) .
State	LT 1.1	LT 1.2	LT 1.3	LT 1.4	LT 1.5	LT 1.6	LT 1.7	LT 1.8	LT 2.1	LT 2.2	LT 2.3	LT 2.4
_
.T&
lw(36p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) .
 {
Transmit
signal 
Receive
signal
 }	SIG 0	SIG 2W	SIG 2W	SIG 2	SIG 2	SIG 4H	SIG 4	SIG 0	SIG 2W	SIG 2	SIG 4H	SIG 4
_
.T&
lw(36p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) .
FE 4 	ST.Tl4;  LT 2.1 	\(em 	LT 2.2  or \(em	LT 2.2  or \(em	LT 2.2  or \(em	\(em	\(em	LT 2.1	:	:	:	:
_
.T&
lw(36p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) .
Exp. of itern. timer\ Tl4	\(em	\(em	\(em	\(em	\(em	\(em	\(em	\(em	LT 2.2	\(em	\(em	\(em  
_
.T&
lw(36p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) | cw(27p) | cw(27p) | cw(27p) | cw(21p) .
Rec. synch. on looped b. sig.	/	/	/	\(em	\(em	\(em	\(em	\(em	/	ST.T12;  LT 2.3	\(em	 {
\(em
\(em
No state change.
 }
.TE
.LP
/
Impossible by the definition of peer\(hyto\(hypeer physical layer procedures or system internal reasons.
.LP
:
Impossible by the definition of the physical layer.
.LP
a, b; LTx
Perform action/issue message a and b; enter state LTx.
.LP
ST.Tlx
Start Timer Tlx.
.nr PS 9
.RT
.ad r
\fBTableau I\(hy1/G.961 (SUITE) [2T6.961] A L'ITALIENNE, p.24\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.PP
The following states support activation when loopback\ 1 is
requested:
.LP
	LT\ 2.1
	The LT sends the awake signal SIG 2W to the NT1
(transparent loopback), on the receipt of FE\ 9, and starts
transmission of SIG\ 2 on expiry of timer\ Tl4.
.LP
	LT\ 2.2
	The LT has operated loopback 1 and is synchronizing
its receiver on the looped back signal.
.LP
	LT\ 2.3
	The LT sends SIG 4H until the expiry of timer Tl2.
.LP
	LT\ 2.4
	The LT is fully active and sends SIG\ 4 to the NT1
(transparent loopback). Loopback\ 1 is operated.
.PP
The LT state transition table is not affected by loopback\ 2 and
1A requests. The corresponding control signals are transferred across channels 
C\dV\\d1\uand CL. 
.sp 1P
.LP
I.10.6
	\fIActivation times\fR 
.sp 9p
.RT
.PP
For definition of activation times see Recommendation\ G.960,
\(sc\ 5.5.
.RT
.LP
	a)
	Maximum activation time for activation occuring immediately
after a deactivation:
.LP
	\(em
	without\ regenerator:
	210 ms.
.LP
	\(em
	with\ regenerator:
	420 ms.
.LP
	b)
	Maximum time for activation occuring after the first
powering of a line
.LP
	\(em
	without\ regenerator:
	1.5 s.
.LP
	\(em
	with regenerator:
	\  |  s.
.sp 1P
.LP
I.11
	\fIJitter\fR 
.sp 9p
.RT
.PP
Jitter tolerances shall assure that the maximum network limit of
jitter (see Recommendation\ G.823) is not exceeded.
.PP
Furthermore, the limits of Recommendation\ I.430 must be supported by the 
jitter limits of the transmission system on local lines. 
.PP
The jitter limits given below must be satisfied regardless of the
length of the local line and the inclusion of repeaters, provided that 
they are covered by the transmission media characteristic (see \(sc\ 3). 
The limits must be met regardless of the transmitted signal. A suitable 
test sequence is for 
further study (see Recommendation\ G.823, \(sc\ 4).
.RT
.sp 1P
.LP
I.11.1
	\fILimits of maximum tolerable input jitter\fR 
.sp 9p
.RT
.PP
The amplitude of the jitter at the NT1 input shall be limited by
the template given in Figure\ I\(hy3/G.961.
.RT
.LP
.rs
.sp 20P
.ad r
\fBFigure I\(hy3/G.961, p.\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.sp 1P
.LP
I.11.2
	\fIOutput jitter of NT1 in absence of input jitter\fR 
.sp 9p
.RT
.PP
When measured with a highpass filter with a 30 Hz cut\(hyoff
frequency, the jitter at the output of the NT1 shall not exceed 0.02\ UIpp.
Without a filter, the jitter shall not exceed 0.1\ UIpp.
.RT
.sp 1P
.LP
I.11.3
	\fITiming extraction jitter\fR 
.sp 9p
.RT
.PP
The jitter at the output of the NT1 shall closely follow the input jitter. 
Therefore, the jitter transfer function of the NT1 shall be less than \(+- | \ 
dB in the frequency range 3\ Hz to 30\ Hz. 
.RT
.sp 1P
.LP
I.11.4
	\fITest conditions for jitter measurements\fR 
.sp 9p
.RT
.PP
For further study.
.RT
.sp 2P
.LP
I.12
	\fITransmitter output characteristics\fR 
.sp 1P
.RT
.sp 1P
.LP
I.12.1
	\fIPulse amplitude\fR 
.sp 9p
.RT
.PP
The amplitude of a transmitted single pulse shall be 2V \(+- | .2V
with a load impedance of 150\ ohm.
.RT
.sp 1P
.LP
I.12.2
	\fIPulse shape\fR 
.sp 9p
.RT
.PP
The shape of a transmitted single pulse shall fit the mask given in Figure\ 
I\(hy4/G.961. 
.RT
.LP
.rs
.sp 32P
.ad r
\fBFigure I\(hy4/G.961, p.\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.sp 1P
.LP
I.12.3
	\fISignal power\fR 
.sp 9p
.RT
.PP
Not specified.
.RT
.sp 1P
.LP
I.12.4
	\fIPower spectrum\fR 
.sp 9p
.RT
.PP
The upper bound of the power spectral density shall be limited
according to Figure\ I\(hy5/G.961.
.RT
.LP
.rs
.sp 27P
.ad r
\fBFigure I\(hy5/G.961, p.\fR 
.sp 1P
.RT
.ad b
.RT
.sp 1P
.LP
I.12.5
	\fITransmitter signal nonlinearity\fR 
.sp 9p
.RT
.PP
Not specified.
.RT
.sp 2P
.LP
I.13
	\fITransmitter/receiver termination\fR 
.sp 1P
.RT
.sp 1P
.LP
I.13.1
	\fIImpedance\fR 
.sp 9p
.RT
.PP
The nominal output/input impedance of the NT1 and LT shall be
150\ ohm.
.RT
.sp 1P
.LP
I.13.2
	\fIReturn loss\fR 
.sp 9p
.RT
.PP
The return loss agains 150 ohm \(+- | % measured for NT1 or LT shall
exceed the limits given in Figure\ I\(hy6/G.961.
.bp
.RT
.LP
.rs
.sp 20P
.ad r
\fBFigure I\(hy6/G.961, p.\fR 
.sp 1P
.RT
.ad b
.RT
.sp 1P
.LP
I.13.3
	\fILongitudinal conversion loss\fR 
.sp 9p
.RT
.PP
The longitudinal conversion loss at the line interface for LT and NT1 shall 
exceed the limits given in Figure\ I\(hy7/G.961. 
.RT
.LP
.rs
.sp 23P
.ad r
\fBFigure I\(hy7/G.961, p.\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp