InfoMagic Standards 1993 July/Disc.iso/ccitt/1988/troff/4_2_03.tro

Text File | 1991-12-13 | 97.5 KB | 3,822 lines

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.rs
\v | 5i'
.sp 1P
.ce 1000
\v'3P'
SECTION\ 8
.ce 0
.sp 1P
.ce 1000
\fBMARITIME\ SYSTEMS\fR
.ce 0
.sp 1P
.sp 2P
.LP
\fBRecommendation\ M.1100\fR
.RT
.sp 2P
.sp 1P
.ce 1000
\fBGENERAL\fR \
\fBMAINTENANCE\ ASPECTS\ OF\ MARITIME\ SATELLITE\ SYSTEMS\fR
.EF '%    Fascicle\ IV.2\ \(em\ Rec.\ M.1100''
.OF '''Fascicle\ IV.2\ \(em\ Rec.\ M.1100    %'
.ce 0
.sp 1P
.LP
\fB1\fR     \fBPurpose\fR
.sp 1P
.RT
.PP
The purpose of this Recommendation is to describe the special
maintenance procedures and facilities that are required for the maintenance
of maritime satellite systems. Wherever possible the standard maintenance
procedures and facilities specified in the Series\ M and\ O
Recommendations should be followed for the maintenance of these systems.
.RT
.sp 2P
.LP
\fB2\fR     \fBDefinitions\fR
.sp 1P
.RT
.PP
The following are definitions of terms used in the maintenance of maritime
satellite systems.
.RT
.sp 1P
.LP
2.1
    \fBmaritime satellite system\fR
.sp 9p
.RT
.PP
In the Maritime Mobile\(hySatellite Service, all of the temporary
connection between a telephone at a ship earth station and the maritime
virtual switching point at a coast earth station. It comprises a \fImaritime
satellite\fR \fIcircuit\fR and a \fImaritime local system\fR . The general
arrangement is shown in
Figure\ 1/M.1100.
.RT
.sp 1P
.LP
2.2
    \fBmaritime satellite circuit\fR
.sp 9p
.RT
.PP
A 4\(hywire circuit between a maritime virtual switching point at a \fIcoast
earth station\fR and the 4\(hywire circuit test access point at a \fIship\fR
\fIearth station\fR , via a satellite repeater.
.RT
.sp 1P
.LP
2.3
    \fBmaritime local system\fR
.sp 9p
.RT
.PP
All the equipment between the 4\(hywire test circuit access point on a
\fIship earth station\fR and a 2\(hywire or 4\(hywire telephone served
by that ship
earth station. It may include 4\(hywire to 2\(hywire termination sets,
echo control equipment, data interfaces, and 4\(hywire or 2\(hywire switching
devices.
.RT
.sp 1P
.LP
2.4
    \fBship earth station (SES)\fR
.sp 9p
.RT
.PP
In the Maritime Mobile\(hySatellite Service, a mobile earth station which
provides a 4\(hywire analogue interface for connection of a \fImaritime\fR
\fIsatellite circuit\fR to a \fImaritime local system\fR and a 4\(hywire
circuit test
access point.
.bp
.RT
.LP
.rs
.sp 31P
.ad r
\fBFigure 1/M.1100, p.\fR
.sp 1P
.RT
.ad b
.RT
.sp 1P
.LP
2.5
    \fBcoast earth station (CES)\fR
.sp 9p
.RT
.PP
In the Maritime Mobile\(hySatellite Service, an earth station, which provides
a 4\(hywire analogue interface for connection of a \fImaritime satellite\fR
\fIcircuit\fR to the international public switched telephone network. It
also
provides circuit test access points and test facilities. (See
Recommendation\ M.1120 for the functions of a coast earth station.)
.RT
.sp 1P
.LP
2.6
    \fBmaritime test terminal (MTT)\fR
.sp 9p
.RT
.PP
A \fIship earth station\fR  | nd a \fImaritime local system\fR  | nstalled
at a coast earth station and used for test purposes.
.RT
.sp 1P
.LP
2.7
    \fBnetwork coordination station (NCS)\fR
.sp 9p
.RT
.PP
A station in the Maritime Mobile\(hySatellite Service that maintains a
pool of frequencies, assigns frequencies on demand from a coast earth station
for use in a maritime satellite circuit, and supervises and monitors the
use of the frequencies. The network coordination station is normally located
at a
coast earth station which is designated by the
satellite system
operator
to fulfill these functions. (See Recommendation\ M.1110 for the functions
of a network coordination station.)
.RT
.sp 1P
.LP
2.8
    \fBcoast earth station test position\fR
.sp 9p
.RT
.PP
A position in a coast earth station that can be used to originate test
calls over the maritime satellite system to the maritime test terminal
and to receive test calls from the maritime test terminal.
.bp
.RT
.sp 2P
.LP
\fB3\fR     \fBGeneral maintenance principles\fR
.sp 1P
.RT
.sp 1P
.LP
3.1
    \fIResponsibilities\fR
.sp 9p
.RT
.PP
In an international connection which includes a ship earth station, the
maritime satellite system may be regarded from a transmission point of
view as analogous to a national network and the maritime local system as
somewhat
analogous to a subscriber terminal within that network. Nevertheless, it
should be noted that the
maritime satellite circuit
is set up between the
coast earth station and the ship earth station on a
demand assignment
basis.  Therefore, a
coast earth station
in the maritime satellite
system may not have the direct responsibility for the maintenance of a
particular maritime satellite circuit
and a particular ship earth station all of the time. The operation and
maintenance of the overall maritime satellite system is the responsibility
of the
maritime satellite system operator
, e.g.\ INMARSAT.
.PP
The maintenance organization in each participating country is in
general responsible for the maintenance of the maritime satellite
circuits.
.RT
.sp 1P
.LP
3.2
    \fIAvailable services\fR
.sp 9p
.RT
.PP
The maritime satellite systems in service provide telex services to
maritime mobile units
in addition to telephone and data services. When instituting maintenance
procedures, Administrations should consider the
utilization of these services for communication, diagnostic and maintenance
purposes, and should also consider that trained technical staff are generally
available at the ship earth station only at the time the ship earth station
is commissioned; however, the ship earth station is usually operated by
a
qualified radio officer who may be able to assist in carrying out simple
test procedures.
.PP
Special services, e.g.\ facsimile and high speed data services, are
being provided over the maritime satellite systems. The development of new
maintenance procedures to support these services will be the subject of
future study.
.RT
.sp 2P
.LP
\fB4\fR \fBInterconnection with the international public switched telephone\fR
\fBnetwork\fR
.sp 1P
.RT
.PP
Interconnection arrangements are considered with reference to
Figure\ 1/M.1100.
.PP
The
maritime virtual switching point
at the coast earth
station is considered to be the interface between test access points\ D and\ E
(see Figure\ 2/M.1100). The circuit between the international switching
centre (ISC) and coast earth station is considered as equivalent to an
international public switched telephone circuit.
.RT
.LP
.rs
.sp 24P
.ad r
\fBFigure 2/M.1100, p.\fR
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.sp 2P
.LP
\fB5\fR \fBLining\(hyup and maintaining international public switched telephone\fR
\fBcircuits\fR
.sp 1P
.RT
.PP
The circuit between the international switching centre and the
coast earth station in Figure\ 1/M.1100 should be lined up and maintained in
accordance with those Series\ M Recommendations appropriate to international
public switched telephone circuits, e.g.\ Recommendations M.580\ [1] and
M.610\ [2].
.RT
.LP
\fB6\fR     \fBLining\(hyup and maintaining maritime satellite circuits\fR
.sp 1P
.RT
.sp 2P
.LP
6.1
    \fIControl, sub\(hycontrol and respective responsibilities\fR
.sp 1P
.RT
.sp 1P
.LP
6.1.1
    \fIGeneral\fR
.sp 9p
.RT
.PP
The assignment of control and sub\(hycontrol stations and respective responsibilities
must address the configuration of the maritime satellite
system. In every case a
control station
must be assigned as regards
circuits, and, in addition,
sub\(hycontrol stations
are required for
efficient maintenance.
.RT
.sp 1P
.LP
6.1.2
    \fIAssignment of control stations\fR
.sp 9p
.RT
.PP
The coast earth station will be the control station for the
maritime satellite circuit.
.RT
.sp 2P
.LP
6.1.3
    \fIAssignment of sub\(hycontrol stations\fR
.sp 1P
.RT
.PP
6.1.3.1
In principle, the ship earth station should act as the
maritime satellite circuit sub\(hycontrol station
. However, the required staff and facilities may not be available to meet
the circuit sub\(hycontrol
responsibilities, and special measures may need to be developed.
.sp 9p
.RT
.PP
6.1.3.2
A
maritime test terminal
may be used to enhance fault
location
and maintenance in the maritime satellite system. In this regard the maritime
test terminal may carry out some tests normally considered to be within
the
province of a sub\(hycontrol station on behalf of a ship earth station.
Whether or not a maritime test terminal should be assigned as a sub\(hycontrol
station is
left for further study when the operation of a maritime test terminal is
further defined.
.sp 1P
.LP
6.1.4
    \fIResponsibilities of control and sub\(hycontrol stations\fR
.sp 9p
.RT
.PP
Control stations dealing with maritime satellite circuits should
fulfill the responsibilities of control stations as defined in the Series\ M
Recommendations in general. The same will apply to sub\(hycontrol stations.
However, the maritime satellite systems present new concepts which require
guidelines inasmuch as a maritime mobile unit is essentially a subscriber
location. See Recommendation\ M.1120.
.RT
.sp 1P
.LP
6.2
    \fITransmission characteristics\fR
.sp 9p
.RT
.PP
The transmission design characteristics for maritime satellite
circuits are given in Recommendation\ G.473\ [3].
.PP
The setting\(hyup, lining\(hyup and maintenance limits of the maritime
satellite circuit between test access points\ E and\ F of Figure\ 2/M.1100
should be as defined in Table\ 1/M.1100 both for the case where no switch
is located at the coast earth station and where a switch is located at
the coast earth
station.
.PP
The loss/frequency limits in Table 1/M.1100 are those which should be met
with the compandors disabled. The measurements to be carried out with the
compandors in circuit are a subject for further study.
.PP
The relative levels at the coast earth station and the ship earth
station are shown in Figure\ 2/M.1100.
.bp
.RT
.ce
\fBH.T. [T1.1100]\fR
.ce
TABLE\ 1/M.1100
.ce
\fBProvisional setting\(hyup, lining\(hyup and
.ce
\fBmaintenance limits\fR
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(90p) | cw(90p) .
Transmission parameters    Maintenance limits (dB)
_
.T&
lw(90p) | lw(90p) .
 {
Loss/frequency relative to the
loss at reference frequency
 }    (See Note)
.T&
lw(90p) | lw(90p) .
Below 300 Hz    Not specified
.T&
lw(90p) | lw(90p) .
\ \ 300\(hy400 Hz    \(em1.2 to +4.4
.T&
lw(90p) | lw(90p) .
\ \ 400\(hy600 Hz    \(em1.2 to +2.6
.T&
lw(90p) | lw(90p) .
\ \ 600\(hy2400 Hz    \(em1.2 to +1.2
.T&
lw(90p) | lw(90p) .
\ 2400\(hy2700 Hz    \(em1.2 to +2.6
.T&
lw(90p) | lw(90p) .
\ 2700\(hy3000 Hz    \(em1.2 to +4.4
.T&
lw(90p) | lw(90p) .
\ 3000\(hy3400 Hz    \(em1.2 to not specified
_
.T&
lw(90p) | lw(90p) .
Idle noise     {
Not yet specified. See
Annex A for further information
 }
.TE
.LP
\fINote\fR
\ \(em\ To avoid distortion introduced by clippers and the gain variations
due to compandors, the 1020\ Hz reference tone used for measuring
the loss shall be set at\ \(em10 dBm0 and the compandors shall be disabled.
.nr PS 9
.RT
.ad r
\fBTable 1/M.1100 [T1.1100], p.\fR
.sp 1P
.RT
.ad b
.RT
.LP
.sp 2
.sp 2P
.LP
6.3
    \fILining\(hyup procedures\fR
.sp 1P
.RT
.sp 1P
.LP
6.3.1
    \fIMeasurement of the loss at the reference frequency\fR
.sp 9p
.RT
.PP
The control station (coast earth station) sends a reference
frequency from 4\(hywire test access E in Figure\ 2/M.1100 at a level of
\(em10\ dBm0. The sub\(hycontrol station (ship earth station) measures
the level at 4\(hywire test access point\ F in Figure\ 2/M.1100 (the \(em5.5\
dBr point). The receive level
should be \(em15.5\ dBm.
.PP
The sub\(hycontrol station (ship earth station) applies a reference
frequency at the 4\(hywire test access\ F in Figure\ 2/M.1100 (the \(em3.5\
dBr point) at a level of \(em13.5\ dBm, i.e.\ \(em10\ dBm0. The control
station (coast earth
station) measures the level at the 4\(hywire test access point. This should be
\(em10\ dBm0 at 4\(hywire test access point E in Figure\ 2/M.1100.
.PP
The tolerance of the loss measurements shall be as specified in
Recommendation\ M.580\ [1].
.RT
.sp 1P
.LP
6.3.2
    \fIMeasurement of loss/frequency response\fR
.sp 9p
.RT
.PP
The loss/frequency characteristic should be measured and recorded at the
following frequencies to check that the objectives contained in
Table\ 1/M.1100 are met:
.PP
420, 1020, 2500, 2800, 3000 Hz.
.PP
The loss/frequency measurements are taken with the compandors
disabled. The measurements to be carried out with the compandors in circuit
are a subject for further study.
.RT
.sp 1P
.LP
6.3.3
    \fIMeasurement of\fR
\fIcircuit noise\fR
.sp 9p
.RT
.PP
The method of measurement of noise is not yet specified and is
under study.
.bp
.RT
.sp 1P
.LP
6.3.4
    \fIMeasurement of\fR
\fIcircuit stability\fR
.sp 9p
.RT
.PP
This test should be performed on maritime satellite circuits which are
2\(hywire terminated at the ship earth station.
.PP
With the echo suppressor disabled and the 2\(hywire portion of the
circuit unterminated (open circuit), a reference frequency is applied at a
level \(em10\ dBm0 to the test access point E in the transmit direction at the
coast earth station. The level measured at the test access point E in the
receive direction should not be more than \(em17\ dBm0.
.RT
.sp 1P
.LP
6.4
    \fIFault reporting procedures\fR
.sp 9p
.RT
.PP
Fault report points (circuit)
should be identified in
accordance
with Recommendation\ M.715\ [4].
.PP
Fault report points (network)
should be identified in
accordance with Recommendation\ M.716\ [5]. One such point is required for the
maritime satellite system and in the INMARSAT system is assigned to the
INMARSAT
operations control centre
(see Recommendation\ M.1110 for the responsibilities of the operations
control centre). However, general
international networking problems should in the first instance be referred
to the fault report points (network) concerned.
.PP
Exchange of contact point information should be in accordance with
Recommendation\ M.93\ [6].
.RT
.sp 1P
.LP
6.5
    \fIMaintenance procedures\fR
.sp 9p
.RT
.PP
Routine measurements on the maritime satellite circuits should be performed
to confirm that the transmission parameter limits listed in
Table\ 1/M.1100 continue to be maintained. These maintenance procedures are
particularly important with respect to the coast earth station transmission
performance.
.PP
The periodicity of the routine measurements is under study.
.RT
.sp 2P
.LP
\fB7\fR     \fBTest facilities at\fR
\fBship earth stations\fR
.sp 1P
.RT
.sp 1P
.LP
7.1
    \fIAutomatic testing\fR
.sp 9p
.RT
.PP
Maritime mobile units operating in marine environments would not in general
have personnel with adequate expertise for testing and maintaining
equipment connected to the international network. Therefore, remote automatic
testing of a ship earth station would be possible by including automatic
test equipment at the coast earth station and the ship earth station. The
required facilities include quiet termination test line and loop around
test line as
given in Recommendation\ O.11\ [7].
.RT
.sp 1P
.LP
7.2
    \fIManual testing\fR
.sp 9p
.RT
.PP
It should be possible to undertake manual testing of the
transmission performance of ship earth stations. This type of test is essential
when a ship earth station is being lined up after it has been repaired.
It
should be possible to initiate the test either from the coast earth station
or from the ship earth station.
.PP
In order to meet these objectives, the ship earth station should, as a
minimum, be equipped with a tone generator and level meter.
.RT
.ce 1000
ANNEX\ A
.ce 0
.ce 1000
(to Recommendation M.1100)
.sp 9p
.RT
.ce 0
.ce 1000
\fBSignal\(hyto\(hynoise ratios of a maritime satellite\fR
.sp 1P
.RT
.ce 0
.ce 1000
\fBcircuit containing speech dependent devices\fR
.ce 0
.PP
As a maritime satellite circuit may contain speech dependent devices (e.g.\
compandors), the customary specification of idle\(hycircuit\(hynoise
is inadequate. The near\(hyterm and long\(hyterm \*Qobjectives\*U of required
speech\(hy
signal\(hyto\(hypsophometrically\(hyweighted\(hynoise ratio as a function
of mean speech
power (dBm0, time\(hyaverage while active), as proposed by Study Group\ XVI are
shown in Figure\ A\(hy1/M.1100. The maintenance limits and method of measurement
are under study.
.bp
.sp 1P
.RT
.LP
.rs
.sp 32P
.ad r
\fBFigure A\(hy1/M.1100, p.\fR
.sp 1P
.RT
.ad b
.RT
.sp 2P
.LP
    \fBReferences\fR
.sp 1P
.RT
.LP
[1]
     CCITT Recommendation \fISetting up and lining up an international circuit\fR
\fIfor public telephony\fR , Vol.\ IV, Rec.\ M.580.
.LP
[2]
    CCITT Recommendation \fIPeriodicity of maintenance measurements on\fR
\fIcircuits\fR , Vol.\ IV, Rec.\ M.610.
.LP
[3]
     CCITT Recommendation \fIInterconnection of a maritime mobile satellite\fR
\fIsystem with the international automatic switched telephone service;\fR
\fItransmission aspects\fR , Vol.\ III, Rec.\ G.473.
.LP
[4]
    CCITT Recommendation \fIFault report point (circuit)\fR , Vol.\ IV,
Rec.\ M.715.
.LP
[5]
    CCITT Recommendation \fIFault report point (network)\fR , Vol.\ IV,
Rec.\ M.716.
.LP
[6]
    CCITT Recommendation \fIExchange of contact point information for the\fR
\fImaintenance of international services and the international network\fR
, Vol.\ IV, Rec.\ M.93.
.LP
[7]
    CCITT Recommendation \fIMaintenance access lines\fR ,
Vol.\ IV, Rec.\ O.11.
.LP
[8]
    CCITT Manual \fITransmission planning of switched telephone\fR
\fInetworks\fR , Chapter\ III, Annex\ 4, ITU, Geneva, 1976.
.bp
.sp 2P
.LP
\fBRecommendation\ M.1110\fR
.RT
.sp 2P
.sp 1P
.ce 1000
\fBMAINTENANCE\ ORGANIZATION\ FOR\ THE\ MARITIME\ SATELLITE\ SERVICE\fR
.EF '%    Fascicle\ IV.2\ \(em\ Rec.\ M.1110''
.OF '''Fascicle\ IV.2\ \(em\ Rec.\ M.1110    %'
.ce 0
.sp 1P
.LP
\fB1\fR     \fBGeneral\fR
.sp 1P
.RT
.PP
In order to ensure satisfactory interworking between the maritime satellite
network and the international public\(hyswitched telephone network, it
is necessary to define the interrelationship between the maintenance
organization for the maritime satellite telephone service and the maintenance
organization for the international automatic and semi\(hyautomatic telephone
service as defined in the Series\ M.700 Recommendations. The general
maintenance aspects of maritime satellite systems are contained in
Recommendation\ M.1100.
.RT
.sp 2P
.LP
\fB2\fR     \fBMaintenance organization as applicable to INMARSAT\fR
.sp 1P
.RT
.PP
The maintenance responsibility within a maritime satellite network is divided
among the ship earth station, the coast earth station, the network coordination
station, and the operations control centre.
.RT
.sp 1P
.LP
2.1
    \fIShip earth station (SES)\fR
.sp 9p
.RT
.PP
The
ship earth station
must be capable of communicating
reliably with the coast earth station and may act as a sub\(hycontrol station
with responsibilities to the coast earth station (see Recommendation\ M.1100,
\(sc\ 6.1). As a sub\(hycontrol station, it is responsible for reporting
noticeable
degradations in the maritime satellite circuits to the coast earth station
and for reporting ship earth station problems to the manufacturer's or
ship's
maintenance agent.
.RT
.sp 1P
.LP
2.2
    \fICoast earth station (CES)\fR
.sp 9p
.RT
.PP
The
coast earth station
provides communication functions
and has the overall coordination responsibility between the ship earth
station and the international public switched telephone network, and the
responsibility of reporting problems to the network coordination station
and the operations
control centre as required. The maintenance functions of the coast earth
station are further described in draft Recommendation\ M.1120.
.RT
.sp 1P
.LP
2.3
    \fINetwork coordination station (NCS)\fR
.sp 9p
.RT
.PP
The
network coordination station
provides communication and maintenance functions within the maritime satellite
system.
.RT
.LP
    a)
    Communication functions such as:
.LP
    \(em
    transmitting the signalling channel to the ship earth
stations;
.LP
    \(em
    assigning telephone channels on demand;
.LP
    \(em
    maintaining a list of busy ship earth stations.
.LP
    b)
    Maintenance functions such as:
.LP
    \(em
    assisting in performing routine system tests;
.LP
    \(em
    monitoring the performance of coast earth stations;
.LP
    \(em
    monitoring, identifying and clearing of unauthorized
transmissions.
.sp 1P
.LP
2.4
    \fIOperations control centre (OCC)\fR
.sp 9p
.RT
.PP
The
operations control centre
provides administrative,
operational and maintenance functions within the maritime satellite
network.
.RT
.LP
    a)
    Administrative functions such as:
.LP
    \(em
    acting as the fault report point (network);
.LP
    \(em
    preparing, controlling and disseminating system information;
.LP
    \(em
    providing a focal point for ships (or their agents,\ etc.),
Administrations or others.
.bp
.LP
    b)
    Routine and normal operational tasks such as:
.LP
    \(em
    liaising with the various space segment suppliers;
.LP
    \(em
    scheduling and coordinating type approval and commissioning
of ship earth stations;
.LP
    \(em
    scheduling and coordinating the bringing into service of
coast earth stations and network coordination stations;
.LP
    \(em
    carrying out some limited monitoring of transmission
parameters;
.LP
    \(em
    analyzing traffic and performance data provided by network
coordination stations and coast earth stations.
.LP
    c)
     Emergency and/or corrective actions, including as required the issue
of broadcast network advisory messages to ship earth
stations, in case of:
.LP
    \(em
    space segment failures;
.LP
    \(em
    extended network coordination stations failures;
.LP
    \(em
    failures of individual coast earth stations;
.LP
    \(em
    incorrect operation of ship earth stations;
.LP
    \(em
    interference in the network.
.sp 2P
.LP
\fB3\fR     \fBCooperation between the general maintenance organization\fR
\fB(Recommendation\ M.710\ [1]) and the maritime satellite maintenance\fR
\fBorganization\fR
.sp 1P
.RT
.PP
Figure 1/M.1110 illustrates the interrelationship between the
general maintenance organization and the maritime satellite maintenance
organization (INMARSAT).
.RT
.LP
.rs
.sp 30P
.ad r
\fBFigure 1/M.1110, p.\fR
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.PP
The relationship between the coast earth station and the
international
switching centre is defined in Recommendation\ M.1120. The relationship
between the elements within the maritime satellite maintenance organization
is a matter for that organization.
.PP
Cooperation in the maintenance of the maritime satellite service
should comprise the following elements in each organization, each of which
represents a set of functions:
.RT
.LP
    \(em
    fault report point (network) (see Recommendation M.716\ [2]);
.LP
    \(em
    network analysis point (see Recommendation M.720\ [3]);
.LP
    \(em
    system availability information point
(see Recommendation\ M.721\ [4]);
.LP
    \(em
    network management (see Recommendation E.413\ [5]);
.LP
    \(em
    restoration control point (see Recommendation
M.725\ [6]).
.sp 2P
.LP
    \fBReferences\fR
.sp 1P
.RT
.LP
[1]
    CCITT Recommendation \fIGeneral maintenance organization for the\fR
\fIinternational automatic and semiautomatic service\fR , Vol.\ IV,
Rec.\ M.710.
.LP
[2]
    CCITT Recommendation \fIFault report point (network)\fR , Vol.\ IV,
Rec.\ M.716.
.LP
[3]
    CCITT Recommendation \fINetwork analysis point\fR , Vol.\ IV, Rec.\ M.720.
.LP
[4]
    CCITT Recommendation \fISystem availability information point\fR ,
Vol.\ IV, Rec.\ M.721.
.LP
[5]
    CCITT Recommendation \fIInternational network management \(em Planning\fR ,
Vol.\ II, Rec.\ E.413.
.LP
[6]
    CCITT Recommendation \fIRestoration control point\fR , Vol.\ IV, Rec.\ M.725.
\v'1P'
.sp 2P
.LP
\fBRecommendation M.1120\fR
.RT
.sp 2P
.ce 1000
\fBFUNCTIONS,\ MAINTENANCE\ RESPONSIBILITIES\ AND\ MAINTENANCE\fR
.EF '%    Fascicle\ IV.2\ \(em\ Rec.\ M.1120''
.OF '''Fascicle\ IV.2\ \(em\ Rec.\ M.1120    %'
.ce 0
.sp 1P
.ce 1000
\fBFACILITIES\ OF\ A\ COAST\ EARTH\ STATION\ FOR\ TELEPHONY\ SERVICES\fR
.ce 0
.sp 1P
.LP
\fB1\fR     \fBGeneral functions\fR
.sp 1P
.RT
.PP
A coast earth station will include the following basic
functions:
.RT
.LP
    \(em
    the provision of reliable communications with ship earth
stations in the basic telephony modes (other services provided
by maritime satellite networks are not addressed in this
Recommendation);
.LP
    \(em
    the provision of an interworking point between the
international public switched telephone network signalling
systems and the maritime satellite signalling system;
.LP
    \(em
    the commissioning and testing of ship earth stations within
the maritime satellite system as requested by the operations
control centre (OCC). (See Recommendation M.1110.);
.LP
    \(em
    the handling of safety and distress services;
.LP
    \(em
    the maintenance of a list of ship earth stations authorized
to have access to the system;
.LP
    \(em
    the collection of data to assist managerial functions,
e.g.\ accounting, traffic records.
.sp 2P
.LP
\fB2\fR     \fBMaintenance responsibilities\fR
.sp 1P
.RT
.PP
The general maintenance aspects of maritime satellite systems are contained
in Recommendation\ M.1100.
.bp
.RT
.sp 1P
.LP
2.1
    \fICoast earth station\fR
.sp 9p
.RT
.PP
A coast earth station is responsible for the following functions
defined in the Series\ M Recommendations:
.RT
.LP
    \(em
    fault report point (circuit) (see Recommendation M.715\ [1]);
.LP
    \(em
    testing point (transmission) (see Recommendation M.717\ [2]);
.LP
    \(em
    testing point (line signalling) (see Recommendation
M.718\ [3]);
.LP
    \(em
    testing point (switching and inter\(hyregister signalling) if
applicable (see Recommendation M.719\ [4]).
.PP
These responsibilities apply to both the maritime satellite system and
the public switched telephone network.
.sp 1P
.LP
2.2
    \fICircuit control and sub\(hycontrol stations\fR
.sp 9p
.RT
.PP
In all cases the control station responsibilities given in
Recommendation\ M.723\ [5] shall be assigned to a coast earth station for
maritime satellite circuits. Although the ship earth station is a customer's
installation, it may act as a sub\(hycontrol station with responsibilities to
the coast earth station (see Recommendation\ M.1100 \(sc\ 6.1).
.RT
.sp 1P
.LP
2.3
    \fIAdvice of ship earth station fault conditions\fR
.sp 9p
.RT
.PP
A coast earth station shall be responsible for advising the
appropriate maintenance point within the maritime satellite network of fault
conditions suspected to be located at a ship earth station and which affect
the Maritime Satellite Service.
.RT
.sp 2P
.LP
\fB3\fR     \fBTest facilities\fR
.sp 1P
.RT
.sp 1P
.LP
3.1
    \fIAccess points\fR
.sp 9p
.RT
.PP
Test access points shall be provided at a coast earth station, and should
desirably include all those described in Recommendation\ M.1100,
i.e.\ points\ C, D, E and\ G in Figure\ 1/M.1100.
.RT
.sp 2P
.LP
3.2
    \fITest facilities for the maritime satellite circuit\fR
.sp 1P
.RT
.sp 1P
.LP
3.2.1
    \fITest equipment requirements\fR
.sp 9p
.RT
.PP
Test equipment is required at a coast earth station to
permit:
.RT
.LP
    \(em
    tracing of faults in the coast earth station equipment;
.LP
    \(em
    checking of transmission characteristics of maritime
satellite circuits;
.LP
    \(em
    testing of maritime signalling procedures;
.LP
    \(em
    testing of channel assignment procedures.
.PP
In many cases the test equipment may be manually connected.
.sp 1P
.LP
3.2.2
    \fICoast earth station test position\fR  | see Figure 1/M.1100)
.sp 9p
.RT
.PP
Each coast earth station shall contain a test position that can be used
to originate test calls over the maritime satellite system to the maritime
test terminal and to receive calls from the maritime test terminal. It
should be equipped to perform the tests listed in \(sc\ 3.2.1.
.RT
.sp 1P
.LP
3.2.3
    \fIMaritime test terminal (MTT)\fR  | see Figure 1/M.1100)
.sp 9p
.RT
.PP
It is a requirement that each coast earth station shall be provided with
a maritime test terminal which includes similar facilities to a normal
ship earth station. It may be used to originate test calls to, and to receive
test calls from, the coast earth station test position via a maritime satellite
circuit, as well as originating test calls into the terrestrial network.
It
should also be equipped to perform the tests listed in \(sc\ 3.2.1.
.bp
.RT
.sp 2P
.LP
3.2.4
    \fIAutomatic test facilities\fR
.sp 1P
.RT
.sp 1P
.LP
    a)
     When a switch is included at the coast earth station, test lines as defined
in Recommenda\(hy
tion\ O.11
.FS
Test lines as defined
in Recommendation O.11\ [6] may be limited to the quiet termination
test line and
the loop\(hyaround test line.
.FE
\ [6] should be provided at the coast earth
station for access by ship earth station via maritime satellite circuits.
.sp 9p
.RT
.LP
    b)
    When a switch is not included at the coast earth station,
test lines as defined in Recommendation\ O.11\ [6] are desirable at the
international switching centre to which a ship earth station may
gain access.
.sp 1P
.LP
3.3
    \fITest facilities for circuits to the international switching centre\fR
.sp 9p
.RT
.PP
The test facilities should be provided in accordance with Series\ M and\
O Recommendations, and may be accessible from the international
switching centre through the coast earth station test position.
.RT
.sp 2P
.LP
\fB4\fR     \fBTelecommunication facilities for maintenance purposes\fR
.sp 1P
.RT
.PP
For further study.
.RT
.sp 2P
.LP
    \fBReferences\fR
.sp 1P
.RT
.LP
[1]
    CCITT Recommendation \fIFault report point (circuit)\fR , Vol.\ IV,
Rec.\ M.715.
.LP
[2]
    CCITT Recommendation \fITesting point (transmission)\fR , Vol.\ IV,
Rec.\ M.717.
.LP
[3]
    CCITT Recommendation \fITesting point (line signalling)\fR , Vol.\ IV,
Rec.\ M.718.
.LP
[4]
    CCITT Recommendation \fITesting point (switching and interregister\fR
\fIsignalling)\fR , Vol.\ IV, Rec.\ M.719.
.LP
[5]
    CCITT Recommendation \fICircuit control station\fR , Vol.\ IV,
Rec.\ M.723.
.LP
[6]
    CCITT Recommendation \fIMaintenance access lines\fR ,
Vol.\ IV, Rec.\ O.11.
.LP
.sp 27
.bp
.sp 1P
.ce 1000
\v'3P'
SECTION\ 9
.ce 0
.sp 1P
.ce 1000
\fBINTERNATIONAL\ PUBLIC\ TELEPHONE\ NETWORK\ MAINTENANCE\fR
.ce 0
.sp 1P
.IP
\fB9.1\ International\ public\ telephone\ network\ information\fR
.sp 1P
.RT
.sp 2P
.LP
\fBRecommendation\ M.1220\fR
.RT
.sp 2P
.sp 1P
.ce 1000
\fBNETWORK\ MAINTENANCE\ INFORMATION\fR
.EF '%    Fascicle\ IV.2\ \(em\ Rec.\ M.1220''
.OF '''Fascicle\ IV.2\ \(em\ Rec.\ M.1220    %'
.ce 0
.sp 1P
.PP
\fB1\fR
Maintenance of the international network is fundamentally
concerned with ensuring that the automatic and semi\(hyautomatic telephone
network (transmission and switching equipment) is functioning in such a
way that it may successfully provide a switched connection of good transmission
quality
whenever required. To achieve this objective it is important that network
maintenance forces have access to relevant information that may assist in
identifying network impairments and to direct corrective action. Such
information goes beyond basic fault reporting and is indicated in
Table\ 1/M.1220.
.sp 1P
.RT
.PP
Some of the information indicated in Table 1/M.1220 is already
exchanged between Administrations in accordance with other Recommendations,
for example, see Recommendation\ E.149\ [1]. An Administration wishing
to make
bilateral agreements to exchange all or some of the remaining items (from
Table\ 1/M.1220), should designate the point in its Administration which
is to receive such information.
.PP
\fB2\fR
This Recommendation considers the transfer and use of
information from a maintenance standpoint. The purpose of transferring
information is to assist maintenance elements in determining circuits and
equipment that are not performing to specified standards.
.sp 9p
.RT
.PP
\fB3\fR
The analysis and investigation of network problems require two types of
information:
.sp 9p
.RT
.LP
    a)
    background information generally available within the
Administration. In this case the intent is not to establish another information
channel but to use data already exchanged between Administrations;
.LP
    b)
    more detailed information relating to particular problems
or conditions which should be exchanged between the appropriate maintenance
elements as required (refer to Series\ M.700\ Recommendations).
.PP
\fB4\fR
Typical background information [\(sc 3, a) above] is listed in
Table 1/M.1220 and can be applied in maintenance activities as follows:
.sp 9p
.RT
.LP
    i)
    Fault report data:
.LP
    \(em
    can identify faults which contribute to both
transmission impairments and poor network utilization;
.LP
    \(em
    can identify deficient network components and direct
corrective action;
.LP
    \(em
    can identify trends.
.bp
.LP
    ii)
    National and international network call completion
information, including the observation of real traffic as per
Recommendation\ E.426\ [2]:
.LP
    \(em
    can be used for comparative purposes to identify
abnormalities that may be caused by faults in the network.
.LP
    iii)
    Routing data and changes thereto as per
Recommendation\ E.149\ [1]:
.LP
    \(em
    can reduce the following results of misrouting of
traffic due to invalid dialling:
.LP
    a)
    calls to fail;
.LP
    b)
    calls to be switched more than necessary;
.LP
    c)
    calls to contribute to congestion on improper
routes;
.LP
    d)
    poor circuit utilization.
.LP
    iv)
    Circuit order of selection. Selection of circuits not in
the sequence agreed upon can cause:
.LP
    \(em
    uneven distribution of traffic among the circuits
involved;
.LP
    \(em
    increased probability of simultaneous seizures which
lead to initial call failure and subsequent re\(hyattempts.
.PP
\fB5\fR
The more detailed information can be obtained from real time
tests, or from near real time reports from traffic monitoring equipment,
and if required from off\(hyline reports using historical data stored on
magnetic tape. Any distribution of maintenance information should clearly
indicate how and
where the information was obtained, a full description of the data presented,
and the period of time during which it was gathered.
.sp 9p
.RT
.PP
\fB6\fR
Experience has shown that the detailed investigation of
particular problems is more efficiently handled by discussion and cooperation
between the appropriate maintenance elements.
.sp 9p
.RT
.PP
\fB7\fR
Account will need to be taken of unique national or
international events, e.g.\ earthquakes, which could influence international
telephone traffic.
.sp 9p
.RT
.LP
.rs
.sp 25P
.ad r
Blanc
.ad b
.RT
.LP
.bp
.ce
\fBH.T. [T1.1220]\fR
.ce
TABLE\ 1/M.1220
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(24p) | cw(156p) | cw(48p) .
Item     {
Typical information needed for network maintenance
 }    Source
_
.T&
cw(24p) | lw(156p) | lw(48p) .
1a     {
Fault report patterns | ua\d\u)\d
 }    Fault reports
.T&
cw(24p) | lw(156p) | lw(48p) .
1b    Fault report trend data    Fault reports
.T&
cw(24p) | lw(156p) | lw(48p) .
2a     {
National network call completion information or the
results of observations carried out on real traffic. | ub\d\u)\d\u,\d | uc\d\u)\d\u,\d | ud\d\u)\d\u,\d | ue\d\u)\d\u,\d | uf\d\u)\d\u,\d | ug\d\u)\d
 }    Administration
.T&
cw(24p) | lw(156p) | lw(48p) .
2b     {
International network call completion information
including results by individual route where available or the results of
observations carried out on real traffic. | uc\d\u)\d\u,\d | ud\d\u)\d\u,\d | ue\d\u)\d\u,\d | uf\d\u)\d\u,\d | ug\d\u)\d\u,\d | uh\d\u)\d\u,\d | ui\d\u)\d\u,\d | uj\d\u)\d
 }    Rec. E.426\ [2]
.T&
cw(24p) | lw(156p) | lw(48p) .
3a    Routing data    Rec. E.149\ [1]
.T&
cw(24p) | lw(156p) | lw(48p) .
3b     {
Routing data changes \uk\d\u)\d
 }    Rec. E.149\ [1]
.T&
cw(24p) | lw(156p) | lw(48p) .
4a    Circuit order of selection    Administration
.T&
cw(24p) | lw(156p) | lw(48p) .
4b     {
Circuit order of selection changes
 }    Administration
.TE
.LP
\ua\d\u)\d
When individual subscribers and/or operator reports are compiled
by common fault types, randomness often gives way to an obvious
configuration (sometimes called a \*Qpattern\*U) to indicate the existence and
nature of the network fault. The analysis for patterns may well be
subdivided into originating, international and terminating network
categories wherein the international domain includes both international
switching centres. A network analysis point could use such information to
identify suspected network components and make referrals or notifications
to the appropriate maintenance forces for corrective actions.
.LP
\ub\d\u)\d
Information to reflect the national network call completion ratio,
if available, would act as a reference with which to compare completion
rates experienced from distant countries.
.LP
\uc\d\u)\d
Abnormal trends or conditions identified should be promptly
brought to the attention of those who can take corrective actions.
.LP
\ud\d\u)\d
It should be stated whether the call completion information was
obtained by sampling over a period or whether all calls over a period were
taken into account. If sampling is used, the size of the sample and the
total
population of calls should be stated so that the statistical tolerances
which
should be assigned to the results may be determined. If all calls are taken
into account, the total number of calls should be stated.
.LP
\ue\d\u)\d
The data collection period should be stated, e.g. weekday, busy
period, 24 hours of a weekday or during a weekend, etc. This is useful in
the assessment of the performance differences between business and social
traffic.
.LP
\uf\d\u)\d
It should be stated whether the data has been subjected to any
filtering process and if so, which process, e.g. code screening and/or
number length validation.
.LP
\ug\d\u)\d
It should be stated whether the information was supplied from
processors in an SPC switching unit and if so, the periods for which
processors were not supplying this data due to overload, etc.
.LP
\uh\d\u)\d
It is desirable that information be taken from the outgoing side
of the originating international switching centre. If it was not
collected from
this point, the location in the network from where the data was
collected and
what losses are included in the data should be stated. The overall use
of this informtion is also under study in Study Group II.
.LP
\ui\d\u)\d
Depending on the location from where the data was collected, it
should be stated either in terms of answer seizure ratio (if the data
is collected from the outgoing side of the originating exchange) or
answer bid from ratio if it is collected from any other point.
.LP
\uj\d\u)\d
The proportion of calls failed due to distant network congestion
should be stated. This is particularly useful if it can be related to
individual area codes. It is appreciated that the ability to classify
calls failures is dependant on the signalling system used.
.LP
\uk\d\u)\d
Information on routing data changes should be exchanged as soon as
it is identified.
.LP
\fBH.T. [T1.1320]\fR
.TS
center box ;
rw(24p) | cw(156p) | lw(48p) .
    TABLE\ A\(hy1/M.1320
.T&
cw(24p) | cw(156p) | lw(48p) .
 {
\fBChannel numbering scheme for data transmission systems
\fBusing 9600\ bit/s data modems\fR
\fBconforming to
\fBRecommendation\ V.29\ [1]\fR
 }
.T&
cw(34p) | cw(28p) | cw(34p) | cw(34p) | cw(28p) .
Aggregate data rate    Multiplex configuration    Sub\(hychannel data rate    Multiplex channel    Channel number
_
.T&
cw(34p) | cw(28p) | cw(34p) | cw(34p) | cw(28p) , ^  | c | c | c | c
^  | c | c | c | c
^  | c | c | c | c
^  | c | c | c | c.
9600 bit/s    \ 1    9600    A    A4
    \ 2    7200 2400    A B    A3 B1    \ 3    4800 4800    A B    A2 B2    \ 4    4800 2400 2400    A B C    A2 B1 C1    \ 5    2400 2400 2400 2400    A B C D    A1 B1 C1 D1
_
.T&
cw(34p) | cw(28p) | cw(34p) | cw(34p) | cw(28p) , ^  | c | c | c | c
^  | c | c | c | c
^  | c | c | c | c
^  | c | c | c | c.
7200 bit/s    \ 6    7200    A    A3
    \ 7    4800 2400    A B    A2 B1    \ 8    2400 2400 2400    A B C    A1 B1 C1
_
.T&
cw(34p) | cw(28p) | cw(34p) | cw(34p) | cw(28p) , ^  | c | c | c | c
^  | c | c | c | c
^  | c | c | c | c
^  | c | c | c | c.
4800 bit/s    \ 9    4800    A    A2
    10    2400 2400    A B    A1 B1
_
.T&
cw(30p) | cw(30p) .
Sub\(hychannel data rate    Assigned number
_
.T&
cw(30p) | cw(30p) .
9600    4
_
.T&
cw(30p) | cw(30p) .
7200    3
_
.T&
cw(30p) | cw(30p) .
4800    2
_
.T&
cw(30p) | cw(30p) .
2400    1
_
.TE
.nr PS 9
.RT
.ad r
\fBtableau 1/M.1220 [T1.1220], p. 6\fR
.sp 1P
.RT
.ad b
.RT
.sp 2P
.LP
    \fBReferences\fR
.sp 1P
.RT
.LP
[1]
    CCITT Recommendation \fIPresentation of routing data\fR , Vol. II,
Rec.\ E.149.
.LP
[2]
    CCITT Recommendation \fIGeneral guide to the percentage of effective\fR
\fIattempts which should be observed for international telephone calls,\fR
Vol.\ II, Rec.\ E.426.
.bp
.IP
\fB9.2\ Assessment of the international public telephone network
performance\fR
.sp 1P
.RT
.sp 2P
.LP
\fBRecommendation\ M.1230\fR
.RT
.sp 2P
.ce 1000
\fBASSESSMENT\ OF\ THE\ PERFORMANCE\fR
.EF '%    Fascicle\ IV.2\ \(em\ Rec.\ M.1230''
.OF '''Fascicle\ IV.2\ \(em\ Rec.\ M.1230    %'
.ce 0
.sp 1P
.ce 1000
\fBOF\ THE\ INTERNATIONAL\ TELEPHONE\ NETWORK\fR
.ce 0
.sp 1P
.LP
\fB1\fR     \fBGeneral\fR
.sp 1P
.RT
.PP
The quality of the international automatic and semiautomatic
telephone service (being studied by Study Group\ II) as experienced by
customers, is of great importance to Administrations. The quality of service
experienced by customers is determined by a number of factors, including
some which are not the direct responsibility of maintenance personnel,
for
example:
.RT
.LP
    \(em
    customer behaviour,
.LP
    \(em
     planning and provision of the network and whether sufficient circuits
and switching equipment exist to meet the call attempts
made by customers,
.LP
    \(em
    the degree to which network management is employed.
.PP
However, it is recognized that maintenance activities and the
maintenance organization can have a considerable influence on the performance
of the international telephone network and, therefore, on the quality of
service experienced by customers. In view of this, the assessment of network
performance is necessary for the efficient maintenance of the international
telephone network.
.PP
From the point of view of maintenance, the assessment of international
network performance involves a measurement of the capability of the overall
network (i.e. international section plus two\ national sections) to establish
a switched connection of good transmission quality whenever required. Such
a
connection may result from customer calls or test calls.
.RT
.sp 2P
.LP
\fB2\fR     \fBMethods of network performance assessment\fR
.sp 1P
.RT
.PP
To meet the needs of network maintenance, information on the
performance of the international telephone network can be obtained from a
number of sources, for example, from subscriber\(hyto\(hysubscriber test
calls as
detailed in Recommendation\ M.1235, but also from service quality observations
as detailed in Recommendations\ E.420\ [1]
.FS
Recommendation\ E.420 in its
\fIgeneral considerations\fR lists the main sources of information on Quality
of
Service as observed by the customer, and defines the principal methods for
measuring Quality of Service. Annex\ A to this Recommendation illustrates an
approach to integrating service quality observations into an overall
problem\(hyinvestigating process.
.FE
, E.421\ [2], E.422\ [3] and E.423\ [4], and
from monitoring of live traffic.
.FS
Monitoring of live traffic is under study by Study Group\ II in connection
with assessing the Quality of Service
experienced by customers, and by Study Group\ IV for network maintenance
purposes.
.FE
.PP
The nature of information obtained (for example verification of
call completion rate, transmission quality, influence of international and
national sections) will depend on the method of network performance assessment
employed.
.PP
While there is a recognized need to continuously assess the
performance of the international telephone network, the actual method by
which this is achieved depends upon the arrangements within and between
Administrations and on the switching technology employed. The choice of
method is left to individual Administrations, to decide on the basis of
their own
particular circumstances.
.RT
.sp 2P
.LP
    \fBReferences\fR
.sp 1P
.RT
.LP
[1]
    CCITT Recommendation \fIChecking the quality of the international\fR
\fItelephone service\fR , Vol.\ II, Rec.\ E.420.
.LP
[2]
    CCITT Recommendation \fIService quality observations\fR , Vol.\ II,
Rec.\ E.421.
.LP
[3]
    CCITT Recommendation \fIObservations on outgoing telephone calls for\fR
\fIQuality of Service\fR , Vol.\ II, Rec.\ E.422.
.LP
[4]
    CCITT Recommendation \fIObservations on traffic set up by operators\fR ,
Vol.\ II, Rec.\ E.423.
.bp
.sp 2P
.LP
\fBRecommendation\ M.1235\fR
.RT
.sp 2P
.ce 1000
\fBUSE\ OF\ AUTOMATICALLY\ GENERATED\ TEST\ CALLS\ FOR\ ASSESSMENT\fR
.EF '%    Fascicle\ IV.2\ \(em\ Rec.\ M.1235''
.OF '''Fascicle\ IV.2\ \(em\ Rec.\ M.1235    %'
.ce 0
.sp 1P
.ce 1000
\fBOF\ NETWORK\ PERFORMANCE\fR
.ce 0
.sp 1P
.LP
\fB1\fR     \fBGeneral\fR
.sp 1P
.RT
.PP
1.1
This Recommendation describes the use of automatic
subscriber\(hyto\(hysubscriber test calls as one of the methods for assessing
overall network performance\ [1]. It is intended as a basis for bilateral
or
multilateral agreements between Administrations interested in this method of
investigating network performance.
.sp 9p
.RT
.PP
1.2
In correspondence with the objectives of efficient maintenance
methods as described in Recommendation\ M.730\ [2] and, in particular, in line
with the application of controlled maintenance methods as explained in
\(sc\ 4 of Recommendation\ M.730\ [2], there is a recognized need to continuously
assess
network performance.
.PP
1.3
Considering the fact that an international call engages both
national and international links, any method for assessing overall network
performance should cover the entire chain of national and international links.
.PP
1.4
Modern switching and transmission systems may have built\(hyin
facilities for checking the overall network performance by means of test
calls set up automatically from the exchange of origin to the exchange
of destination of international calls. Similar facilities may be provided
by
independent test call generators having access to the switching multiple
at the exchange of origin and making test calls to various test call responders
in
distant countries. Such test call responders may be connected to test numbers
in various terminal exchanges in the distant country.
.PP
1.5
Automatic subscriber\(hyto\(hysubscriber test calls
performed
either by system\(hyindependent test call generators and test call responders,
or by built\(hyin facilities performing the same functions, can be applied
in
bilateral test call programmes
involving the networks of two
Administrations or regional programmes involving more than two Administrations.
It is important that such programmes are well planned and not interfered
with by the use of the same test number for other purposes as well.
.PP
1.6
In order to reflect the real network performance, test call
programmes should be carried out both during non\(hybusy and busy periods. The
number of test calls to be generated on each selected route will depend
on the frequency of difficulties encountered on the route and is independent
of the
traffic load carried on the route, or the size of the route. In other words,
the higher the fault frequency, the fewer test calls will be required to
arrive at statistically significant results. Considering that most of a
test
generator's occupation time is used for sending address information to
its own national switching equipment, international links and national
links in the
distant country are only occupied for a very short time by a test call. The
additional load created by test call generators on international traffic
routes is therefore normally negligible even on very small routes.
.PP
1.7
It should be stressed that test call programmes of the type
described here always necessitate an agreement between Administrations
concerned.
.sp 2P
.LP
\fB2\fR     \fBMethods of assessment\fR
.sp 1P
.RT
.sp 1P
.LP
2.1
    \fIDistribution of test call facilities\fR
.sp 9p
.RT
.PP
For practical purposes it is quite sufficient to generate, and
observe, test calls from a few major traffic points in the originating
country to a few major points in the distant country.
.RT
.sp 1P
.LP
2.2
    \fIProgramming of\fR
\fItest call traffic\fR
.sp 9p
.RT
.PP
In order to avoid interference with other test calls, test call
programmes should be carefully planned and agreed upon by the parties
concerned. It might be advisable to prepare periodical test call programmes
for bilateral exchange between Administrations. Test calls should, if possible,
also be evenly distributed over a period of time including both non\(hybusy and
busy periods of traffic.
.bp
.RT
.sp 1P
.LP
2.3
    \fINumber of test calls\fR
.sp 9p
.RT
.PP
The number of test calls to be generated to each selected
destination is only dependent on the frequency of difficulties encountered
and is independent of the traffic load carried to that destination. Fewer
test
calls are needed to identify the network performance level when the rate of
difficulty encountered is high.
.PP
The number of test calls to be generated in a test call programme for a
defined period of time can normally be divided between all destinations
to be tested. It is recommended, however, that a certain proportion of
the total test call production capacity be utilized for special fault investigations
on
certain indicated destinations.
.RT
.sp 1P
.LP
2.4
    \fIResult of test call programmes\fR
.sp 9p
.RT
.PP
Network performance may be expressed as the ratio of successful to total
test call attempts to a certain international destination during a period
of time. The accuracy of the results of the test calls may be judged by
ordinary statistical methods.
.PP
The definition of a successful or nonsuccessful call is, to some
extent, dependent on the range of tests being interchanged between the test
call generator and the responder. In general, the following criteria must be
met by a successful test call:
.RT
.LP
    i)
    the called party answers,
.LP
    ii)
    acceptable general transmission quality,
.LP
    iii)
    correct charging,
.LP
    iv)
    correct disconnection of the call.
.PP
Furthermore, certain test facilities may be designed to carry out more
stringent test programmes under the network performance concept.
.PP
The nonsuccessful calls should be specified with regard to the type
of fault which occurred.
.RT
.sp 1P
.LP
2.5
    \fIReports and exchange of information\fR
.sp 9p
.RT
.PP
Administrations involved in test call programmes are urged to
exchange test results regularly.
.PP
An unusually high number of network difficulties encountered in a test
call programme should be treated as a fault report and be dealt with according
to fault reporting procedures, without interrupting the test call programme.
.PP
It is recommended that the Administration making test calls should be responsible
for the compilation of the results of those tests.
.RT
.sp 2P
.LP
\fB3\fR     \fBEquipment\fR
.sp 1P
.RT
.PP
As tone signals and other local conditions vary from one national network
to another, test call generators and responders must be specifically
designed for each international application. Furthermore, test call generators
may be designed to interwork with responders in the distant country, which
regenerate test calls back to the country of origin.
.PP
Until such time as Recommendations are available giving the
specifications for test call generating and responding equipments, it is
recommended that Administrations initiating test call programmes supply the
responders required.
.RT
.sp 2P
.LP
    \fBReferences\fR
.sp 1P
.RT
.LP
[1]
    CCITT Recommendation \fITest calls\fR , Vol.\ II, Rec.\ E.424.
.LP
[2]
    CCITT Recommendation \fIMaintenance methods\fR , Vol.\ IV, Rec.\ M.730.
.LP
.rs
.sp 4P
.ad r
Blanc
.ad b
.RT
.LP
.bp
.sp 1P
.ce 1000
\v'3P'
SECTION\ 10
.ce 0
.sp 1P
.ce 1000
\fBINTERNATIONAL\ DATA\ TRANSMISSION\ SYSTEMS\fR
.ce 0
.sp 1P
.sp 2P
.LP
\fBRecommendation M.1300\fR
.RT
.sp 2P
.ce 1000
\fBINTERNATIONAL\ DATA\ TRANSMISSION\ SYSTEMS\ OPERATING\fR
.EF '%    Fascicle\ IV.2\ \(em\ Rec.\ M.1300''
.OF '''Fascicle\ IV.2\ \(em\ Rec.\ M.1300    %'
.ce 0
.sp 1P
.ce 1000
\fBAT\ 2400\ bit/s\ AND\ ABOVE\fR
.ce 0
.sp 1P
.LP
\fB1\fR     \fBGeneral description\fR
.sp 1P
.RT
.PP
1.1
Figure 1/M.1300 illustrates the composition of an international data transmission
system and the nomenclature used.
.sp 9p
.RT
.PP
International data transmission systems may operate at the
following typical bit rates: 2.4, 4.8, 7.2, 9.6, 14.4, 48, 50, 56, 64, 128,
192, 256, 384, 768\ kbit/s and above.
.PP
Several independent data transmission channels may be multiplexed
together to form a transmission system operating at an aggregate bit rate
of, for example, 9.6, 56, 1544, 2048\ kbit/s and above (see
Figure\ 2/M.1300).
.PP
Other bit rates or ranges of bit rates are the subject of further
study and may be addressed in other M.1300\(hySeries Recommendations and/or
Recommendation\ M.1300.
.RT
.LP
.rs
.sp 22P
.ad r
\fBFigure 1/M.1300, p.\fR
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.PP
1.2
International data transmission links
can be
provided on a variety of transmission media in various combinations:
.sp 9p
.RT
.LP
    \(em
    local line plant;
.LP
    \(em
    FDM carrier systems
operating at a basic group band of 60\(hy108\ kHz (e.g. symmetric pair
or coaxial cables,
microwave radio links, satellites);
.LP
    \(em
    voice grade analogue or digital channels;
.LP
    \(em
    digital links (coaxial or optical fibre systems,
microwave radio links, satellite systems).
.PP
Appropriate modems or interface adapters are used to provide
signals suitable to the transmission medium being used.
.PP
1.3
For data transmission links routed via a mixture of
transmission media (for example, analogue, digital, satellite
single\(hychannel\(hyper\(hycarrier), the term \*Qcircuit section\*U is used to
refer to a section of the overall link routed wholly on one type of
transmission medium.
.sp 9p
.RT
.PP
1.4
International data transmission systems can be established
between Administrations to provide channels for various services.
Figure\ 2/M.1300 illustrates an example of an international 56\ kbit/s data
transmission system used for such purposes.
.sp 9p
.RT
.LP
.rs
.sp 33P
.ad r
\fBFigure 2/M.1300, p.\fR
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.sp 2P
.LP
\fB2\fR     \fBData transmission link control and sub\(hycontrol stations\fR
.sp 1P
.RT
.PP
2.1
One
control station
for each data transmission link
should be agreed bilaterally between the Administrations involved prior to
setting up the link. Principles concerning the definition, responsibilities,
functions and appointment of control stations may be found in
Recommendation\ M.1012.
.sp 9p
.RT
.PP
2.2
One
sub\(hycontrol station
for each data transmission link should be agreed bilaterally between Administrations
involved prior to setting up the link. Principles concerning the definition,
responsibilities, functions and appointment of sub\(hycontrol stations
may be found in Recommendation\ M.1013.
.sp 9p
.RT
.sp 2P
.LP
\fB3\fR     \fBReserve arrangements\fR
.sp 1P
.RT
.PP
3.1
Since data transmission links of this nature often carry
private leased data systems and/or TDM telegraph systems, some Administrations
find it useful to provide a nominated
reserve link
for restoration
purposes in the event of failure of the
normal link
. This should be
decided by bilateral agreement between Administrations at the time of
setting up the link
. Such reserve links must be lined up to meet the requirements of the normal
data transmission link.
.sp 9p
.RT
.PP
3.2
Wherever possible, such reserve links should follow a different
route
from the route of the normal link.
.sp 9p
.RT
.sp 2P
.LP
\fB4\fR     \fBDesignations\fR
.sp 1P
.RT
.PP
4.1
The form of designation for the data transmission system and
the data transmission link and its nominated reserve may be found in
Recommendation\ M.140, \(sc\ 11\ [1].
.sp 9p
.RT
.PP
4.2
Where the situation illustrated in Figure 2/M.1300 applies, the numbering
scheme for derived channels should be in accordance with
Recommendation\ M.1320
.FS
Recommendation\ M.1320 is currently limited to data
transmission of systems operating up to 9.6\ kbit/s. Further study is required
to derive a suitable numbering scheme for data transmission systems operating
at 14.4\ kbit/s and above.
.FE
.
.sp 9p
.RT
.sp 2P
.LP
\fB5\fR \fBLine\(hyup and maintenance of data transmission\fR \fBsystems
and links operating in the range 48\ kbit/s and above\fR
.sp 1P
.RT
.PP
5.1
For guidance on the setting up and lining up of the higher
speed international data transmission systems and links operating within
this range, reference should be made to Recommendation\ M.1370.
.sp 9p
.RT
.PP
5.2
For the maintenance methods, procedures and limits that apply to such data
transmission systems and links, reference should be made to
Recommendation\ M.1375.
.sp 9p
.RT
.sp 2P
.LP
\fB6\fR \fBLine\(hyup and maintenance of data transmission\fR \fBsystems
and links operating in the range 2.4 kbit/s to 14.4\ kbit/s\fR
.FS
Data   transmission systems operating at 19.2\ kbit/s requires further study.
.FE
.sp 1P
.RT
.PP
6.1
For guidance on the setting up and lining up of international data transmission
systems and links operating within this range, refer to
Recommendation\ M.1350.
.sp 9p
.RT
.PP
6.2
For the maintenance methods, procedures and limits that apply to such data
transmission systems and links, refer to Recommendation M.1355.
.sp 9p
.RT
.sp 2P
.LP
    \fBReference\fR
.sp 1P
.RT
.LP
[1]
     CCITT Recommendation \fIDesignation of international circuits, groups,\fR
\fIgroup and line links, digital blocks, digital paths, data transmission\fR
\fIsystems and related information\fR , Vol.\ IV, Rec.\ M.140.
.bp
.sp 2P
.LP
\fBRecommendation M.1320\fR
.RT
.sp 2P
.sp 1P
.ce 1000
\fBNUMBERING\ OF\ CHANNELS\ IN\ DATA\ TRANSMISSION\ SYSTEMS\fR
.EF '%    Fascicle\ IV.2\ \(em\ Rec.\ M.1320''
.OF '''Fascicle\ IV.2\ \(em\ Rec.\ M.1320    %'
.ce 0
.sp 1P
.PP
Using suitable modems and multiplexers it is possible to
provide for a combination of data channels multiplexed together to form an
aggregate bit rate for transmission purposes.
.sp 1P
.RT
.PP
The principle shown in Annex\ A and Figure 1/M.1320 may be applied to higher
bit rates as modems, etc., are developed and deployed.
.PP
The numbering of data channels is obtained by indicating the
multiplex channel followed by the sub\(hychannel data rate assigned number in
accordance with the scheme contained in Table\ A\(hy1/M.1320.
.PP
As an example, Figure 1/M.1320 shows a data transmission system,
London\(hyMontreal 96H001, employing equipment providing for 2\ channels at
2400\ bit/s and one channel at 4800\ bit/s forming an aggregate bit rate of
9600\ bit/s.
.PP
For this system the channel numbering would be:
.PP
London\(hyMontreal 96H001/A2
.PP
London\(hyMontreal 96H001/B1
.PP
London\(hyMontreal 96H001/C1
.RT
.LP
.rs
.sp 30P
.ad r
\fBFigure 1/M.1320, p.\fR
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.ce 1000
ANNEX\ A
.ce 0
.ce 1000
(to Recommendation M.1320)
.sp 9p
.RT
.ce 0
.PP
Table A\(hy1/M.1320 shows the channel numbering scheme for data transmission
systems operated at an aggregate data rate of 9600\ bit/s.
The table also shows the channel numbering scheme for systems using
9600\ bit/s modems operated at reduced data rates of 7200\ bit/s or 4800\
bit/s.
.sp 1P
.RT
.LP
.sp 1
.ce
\fBH.T. [T1.1320]\fR
.ce
TABLE\ A\(hy1/M.1320
.ce
\fBChannel numbering scheme for data transmission systems
.ce
\fBusing 9600\ bit/s data modems\fR
.ce
\fBconforming to
.ce
\fBRecommendation\ V.29\ [1]\fR
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(34p) | cw(28p) | cw(34p) | cw(34p) | cw(28p) .
Aggregate data rate    Multiplex configuration    Sub\(hychannel data rate    Multiplex channel    Channel number
_
.T&
cw(34p) | cw(28p) | cw(34p) | cw(34p) | cw(28p) , ^  | c | c | c | c
^  | c | c | c | c
^  | c | c | c | c
^  | c | c | c | c.
9600 bit/s    \ 1    9600    A    A4
    \ 2    7200 2400    A B    A3 B1    \ 3    4800 4800    A B    A2 B2    \ 4    4800 2400 2400    A B C    A2 B1 C1    \ 5    2400 2400 2400 2400    A B C D    A1 B1 C1 D1
_
.T&
cw(34p) | cw(28p) | cw(34p) | cw(34p) | cw(28p) , ^  | c | c | c | c
^  | c | c | c | c
^  | c | c | c | c
^  | c | c | c | c.
7200 bit/s    \ 6    7200    A    A3
    \ 7    4800 2400    A B    A2 B1    \ 8    2400 2400 2400    A B C    A1 B1 C1
_
.T&
cw(34p) | cw(28p) | cw(34p) | cw(34p) | cw(28p) , ^  | c | c | c | c
^  | c | c | c | c
^  | c | c | c | c
^  | c | c | c | c.
4800 bit/s    \ 9    4800    A    A2
    10    2400 2400    A B    A1 B1
_
.T&
cw(30p) | cw(30p) .
Sub\(hychannel data rate    Assigned number
_
.T&
cw(30p) | cw(30p) .
9600    4
_
.T&
cw(30p) | cw(30p) .
7200    3
_
.T&
cw(30p) | cw(30p) .
4800    2
_
.T&
cw(30p) | cw(30p) .
2400    1
_
.TE
.nr PS 9
.RT
.ad r
\fBTable A\(hy1/M.1320 [T1.1320], p.\fR
.sp 1P
.RT
.ad b
.RT
.LP
.sp 5
.sp 2P
.LP
    \fBReference\fR
.sp 1P
.RT
.LP
[1]
     CCITT Recommendation \fI9600 bits per second modem standardized for use\fR
\fIon point\(hyto\(hypoint 4\(hywire leased telephone\(hytype circuits\fR
, Vol.\ VIII,
Rec.\ V.29.
.bp
.sp 2P
.LP
\fBRecommendation M.1350\fR
.RT
.sp 2P
.ce 1000
\fBSETTING\ UP,\ LINING\ UP\ AND\ CHARACTERISTICS\ OF\ INTERNATIONAL\ DATA\fR
.EF '%    Fascicle\ IV.2\ \(em\ Rec.\ M.1350''
.OF '''Fascicle\ IV.2\ \(em\ Rec.\ M.1350    %'
.ce 0
.sp 1P
.ce 1000
\fBTRANSMISSION\ SYSTEMS\ OPERATING\ IN\ THE\ RANGE\ 2.4\ kbit/s\ TO\ 14.4\
kbit/s\fR
.ce 0
.sp 1P
.LP
\fR \fB1\fR     \fBGeneral\fR
.sp 1P
.RT
.PP
This Recommendation deals with the setting up, lining up and
characteristics of international data transmission systems operating at
speeds in the range 2.4 to\ 14.4\ kbit/s. The system may be a single connection
operating at 2.4, 4.8, 7.2, 9.6 or 14.4\ kbit/s, or a combination of the
lower speed systems, multiplexed onto the 9.6 or 14.4\ kbit/s system.
.PP
These systems may be carried on data links comprised of
voice
grade circuits
(either analogue or digital), or multiplexed onto higher bit rate data
transmission systems as described in Recommendation\ M.1300.
.PP
The system may terminate at terminal international centres, terminal national
centres or, when multiplexing is employed to derive several channels, a
combination of several termination configurations may be provided. See
Figure\ 1/M.1300 and Figure\ 2/M.1300 for further information.
.PP
When an international data transmission system is assigned its
designation (according to Recommendation\ M.140, \(sc\(sc 3.2.15 and 11\
[1]), the
Administration with control station responsibility will assemble the necessary
technical and operational information. This should be entered into the
list of Related Information (as defined in Recommendation\ M.140, \(sc\
12\ [1]) which
consists of the items shown in Annex\ A to this Recommendation.
.RT
.sp 2P
.LP
\fB2\fR     \fBCharacteristics of data links\fR
.sp 1P
.RT
.sp 1P
.LP
2.1
    \fIAnalogue data links\fR
.sp 9p
.RT
.PP
The transmission characteristics of analogue circuits to be used as data
links are based upon Recommendation\ M.1020 where these links utilize
modems without in\(hybuilt equalizers
. Alternatively, the relaxed
loss/frequency and group\(hydelay distortion limits specified in
Recommendation\ M.1025 may be applied for those systems utilizing
modems
with built\(hyin equalizers
where agreed between the Administrations involved and if tests confirm
suitability.
.RT
.sp 1P
.LP
2.2
    \fIDigital data links\fR
.sp 9p
.RT
.PP
Where the data systems are multiplexed onto higher bit rate data
transmission systems, the data link is set up in accordance with the
requirements of the higher bit rate system, see Recommendation\ M.1370.
.RT
.sp 2P
.LP
\fB3\fR     \fBSetting up and lining up the data transmission system\fR
.sp 1P
.RT
.sp 1P
.LP
3.1
    \fISetting up and testing an analogue data link\fR
.sp 9p
.RT
.PP
The analogue data link is set up and tested in accordance with the principles
and procedures detailed in Recommendation\ M.1050. In this regard
the data link is to be considered as a special circuit.
.PP
Suitable adjustments may be made to the procedures stated in
Recommendation\ M.1050 where the system terminates in terminal international
centres or terminal national centres, rather than in renters premises.
.bp
.RT
.sp 1P
.LP
3.2
    \fISetting up and testing a digital data link\fR
.sp 9p
.RT
.PP
(Under study).
.RT
.sp 2P
.LP
3.3
    \fIOverall system tests\fR
.sp 1P
.RT
.PP
3.3.1
When the various sections have been set up and lined up and
interconnected using any necessary equipment to form an end\(hyto\(hyend
system,
overall system data tests shall be made. The objectives for these tests are
as shown in Table 1/M.1350.
.sp 9p
.RT
.LP
.sp 1
.ce
\fBH.T. [T1.1350]\fR
.ce
TABLE\ 1/M.1350
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(42p) | cw(42p) | cw(42p) | cw(60p) .
Data rate  bit/s    Error ratio    Error in 15\ min    % error\(hyfree seconds
_
.T&
cw(42p) | cw(42p) | cw(42p) | cw(60p) .
\ 2 | 00    1 \(mu 10\uD\dlF261\u5\d    22    Better than 92%
.T&
cw(42p) | cw(42p) | cw(42p) | cw(60p) .
\ 4 | 00    1 \(mu 10\uD\dlF261\u5\d    43    Better than 92%
.T&
cw(42p) | cw(42p) | cw(42p) | cw(60p) .
\ 7 | 00    1 \(mu 10\uD\dlF261\u5\d    65    Better than 92%
.T&
cw(42p) | cw(42p) | cw(42p) | cw(60p) .
\ 9 | 00    1 \(mu 10\uD\dlF261\u5\d    86    Better than 92%
.T&
cw(42p) | cw(42p) | cw(42p) | cw(60p) .
14 | 00    (under study)    (under study)    (under study)
_
.TE
.nr PS 9
.RT
.ad r
\fBTable 1/M.1350 [T1.1350], p.\fR
.sp 1P
.RT
.ad b
.RT
.LP
.sp 6
.PP
3.3.2
Where agreed between Administrations involved, or when
end\(hyto\(hyend tests indicate less than satisfactory performance, sectionalizing
tests may be performed (see Recommendation\ M.1355, \(sc\ 3.5).
.PP
3.3.3
Bit error ratio and/or error free seconds tests are to be
performed utilizing a 511\ bit
pseudorandom test pattern
as described
in Recommendation\ V.52\ [2]. Alternatively, other patterns such as the
2047\ bit pseudorandom pattern may be used when agreed between Administrations.
.sp 2P
.LP
\fB4\fR     \fBRecording of results\fR
.sp 1P
.RT
.PP
All measurement results are to be recorded for later reference
during maintenance measurements.
.RT
.sp 2P
.LP
\fB5\fR     \fBLimits for bit error ratio and error free seconds\fR
.sp 1P
.RT
.PP
Provisional limits for bit error ratio and error free seconds are given
in Table\ 1/M.1350. These limits are subject to further study. For further
information see Recommendation\ G.821\ [3].
.RT
.sp 2P
.LP
\fB6\fR     \fBAllocation of overall objectives\fR
.sp 1P
.RT
.PP
The allocation of the error performance objectives indicated in
Table\ 1/M.1350 for the end\(hyto\(hyend system is under study.
.bp
.RT
.ce 1000
ANNEX\ A
.ce 0
.ce 1000
(to Recommendation M.1350)
.sp 9p
.RT
.ce 0
.ce 1000
\fBDesignation information on international data transmission systems\fR
.sp 1P
.RT
.ce 0
.LP
A.1
    \fIDesignation\fR
.sp 1P
.RT
.PP
The designation is according to Recommendation M.140 [1], \(sc\ 11 (for
use between Administrations) or \(sc\ 3.2.15 (for private use).
.RT
.sp 1P
.LP
A.2
    \fIRelated information\fR
.sp 9p
.RT
.LP
    RI 1.
    Urgency for restoration;
.LP
    RI 2.
    Terminal countries;
.LP
    RI 3.
    Administrations', carriers' or broadcasting companies'
names;
.LP
    RI 4.
    Control and sub\(hycontrol station(s);
.LP
    RI 5.
    Fault report points;
.LP
    RI 6.
    Routing;
.LP
    RI 7.
    Association;
.LP
    RI 8.
    Equipment information;
.LP
    RI 9.
    Use;
.LP
    RI 10.
    Transmission medium information;
.LP
    RI 11.
    Composition of transmission;
.LP
    RI 12.
    (Empty item, use: \*Q\(em;\*U);
.LP
    RI 13.
    Occupancy.
.PP
The various items will be dealt with in \(sc\ 12 of
Recommendation\ M.140\ [1].
.sp 2P
.LP
    \fBReferences\fR
.sp 1P
.RT
.LP
[1]
    CCITT Recommendation \fIDesignation of international circuits, groups\fR
\fIand line links, digital blocks, digital paths, data transmission systems\fR
\fIand related information\fR , Vol.\ IV, Rec.\ M.140.
.LP
[2]
    CCITT Recommendation \fICharacteristics of distortion and error\(hyrate\fR
\fImeasuring apparatus for data transmission\fR , Vol.\ VIII, Rec.\ V.52.
.LP
[3]
    CCITT Recommendation \fIError performance on an international digital\fR
\fIconnection forming part of an integrated services digital network\fR ,
Vol.\ III, Rec.\ G.821.
\v'6p'
.sp 2P
.LP
\fBRecommendation\ M.1355\fR
.RT
.sp 2P
.ce 1000
\fBMAINTENANCE\ OF\ INTERNATIONAL\ DATA\ TRANSMISSION\ SYSTEMS\ OPERATING\fR
.EF '%    Fascicle\ IV.2\ \(em\ Rec.\ M.1355''
.OF '''Fascicle\ IV.2\ \(em\ Rec.\ M.1355    %'
.ce 0
.sp 1P
.ce 1000
\fBIN\ THE\ RANGE\ 2.4\ TO\ 14.4\ kbit/s\fR
.ce 0
.sp 1P
.LP
\fB1\fR     \fBGeneral\fR
.sp 1P
.RT
.PP
1.1
This Recommendation deals with maintenance procedures
applicable to international data systems in the range 2.4 to\ 14.4\ kbit/s.
.sp 9p
.RT
.PP
1.2
The constituent parts of the data system are shown in
Figures\ 1/M.1300 and\ 2/M.1300.
.PP
1.3
In some instances it may be necessary to provide modems at a
centre, for testing purposes only, to achieve adequate performance in fault
localization.
.sp 2P
.LP
\fB2\fR     \fBFault reporting\fR \fBprocedures\fR
.sp 1P
.RT
.PP
2.1
As far as possible, the provisions of Recommendations\ M.1012, M.1013 and
M.1014 apply. Any additional special procedures must be devised by the
Administrations concerned.
.bp
.sp 9p
.RT
.sp 2P
.LP
\fB3\fR     \fBFault localization\fR
.sp 1P
.RT
.PP
3.1
Upon receipt of a complaint about the performance of an
international data transmission system the control or sub\(hycontrol station
should obtain specific assurance that all terminal equipment has been tested
and is working correctly.
.sp 9p
.RT
.PP
3.2
The
control station
should first ensure that all major
systems are performing normally, then efforts should be made to localize and
clear the fault.
.PP
3.3
It is essential that the control and
sub\(hycontrol stations
inform each other of all relevant information and significant actions taken
which may assist their efforts.
.PP
3.4
Control and sub\(hycontrol stations should arrange that a suitable
test pattern
is transmitted in each direction. Then, if the fault is
not cleared, suitable modems and test equipment can be applied at intermediate
points as appropriate in order to isolate the fault to a particular section.
.PP
3.5
To localize the fault, the data transmission system should
normally be tested in sections so that the need for international cooperation
is reduced and rapid progress is made. In some instances loops may be utilized
in order to isolate the faulty section. Care must be taken to avoid the
simultaneous operation of loops if the system configuration is such that
erroneous results would occur.
.PP
3.6
The purpose of the initial fault localization process is to
identify as quickly as possible whether the fault lies in one of the national
sections or the international section. This allows the Administrations
to
begin the detailed investigation necessary to clear the fault.
.PP
3.7
See Figure 1/M.1375 for a guide to fault localization.
.sp 2P
.LP
\fB4\fR     \fBOverall data system check\fR
.sp 1P
.RT
.PP
4.1
When the fault has been localized to the international or a
national section and cleared, that section should be tested to ensure that
its bit error ratio meets the requirements of \(sc\ 5 below.
.sp 9p
.RT
.PP
4.2
The overall data transmission system should also meet the
requirements of \(sc\ 5, and the data transmission performance should be tested
before the system is offered back to the renter.
.sp 2P
.LP
\fB5\fR     \fBMaintenance parameters\fR
.sp 1P
.RT
.PP
5.1
Maintenance measurements should normally be evaluated by
comparison with those made during the line\(hyup of the system and with the
specified limits given in Recommendation\ M.1350.
.sp 9p
.RT
.PP
5.2
For data transmission performance, it will normally be sufficient to check
the bit error ratio over 15\ minutes. Alternatively, error free seconds
may be used as a measure of performance, where agreed between Administrations
concerned. The maintenance standards are given in Table\ 1/M.1350.
.sp 2P
.LP
\fBRecommendation\ M.1370\fR
.RT
.sp 2P
.ce 1000
\fBSETTING\ UP\ AND\ LINING\ UP\ OF\ INTERNATIONAL\ DATA\fR  |
\fBTRANSMISSION\ SYSTEMS\fR
.EF '%    Fascicle\ IV.2\ \(em\ Rec.\ M.1370''
.OF '''Fascicle\ IV.2\ \(em\ Rec.\ M.1370    %'
.ce 0
.sp 1P
.ce 1000
\fB OPERATING\ AT\fR  |
\fB48\ kbit/s\ AND\ ABOVE\fR
.ce 0
.sp 1P
.LP
\fB1\fR     \fBScope\fR
.sp 1P
.RT
.PP
1.1
This Recommendation deals with the setting up and lining up of international
data transmission systems operating at 48\ kbit/s
and above as described in Recommendation\ M.1300.
.sp 9p
.RT
.sp 2P
.LP
\fB2\fR     \fBGeneral setting\(hyup and lining\(hyup procedures\fR
.sp 1P
.RT
.PP
2.1
The procedure described in this Recommendation follow the
general setting\(hyup and lining\(hyup principles adopted by Study Group\ IV
throughout the Series\ M Recommendations.
.bp
.sp 9p
.RT
.PP
2.2
Associated equipment should be correctly set up. Individual
circuit sections (for definition, see \(sc\ 1.3 of Recommendation\ M.1300)
should
be lined up as separate entities in accordance with the Recommendations and
procedures appropriate to the transmission medium involved.
.PP
2.3
Where a circuit section exists wholly within the territory of a
single Administration, national practices may be used for lining up that
circuit section providing the requirements for data transmission performance
of the complete national section are met.
.PP
2.4
The individual circuit sections, should be lined up and
interconnected to form the national or international section. This section
should then be lined up overall and checked for data transmission performance.
When the international and national sections have been checked and found
to be satisfactory they should then be interconnected to form the overall
system and end\(hyto\(hyend data performance tests made.
.PP
2.5
When an international data transmission system is assigned its
designation (according to Recommendation\ M.140, \(sc\(sc 3.2.15 and 11\
[1]), the
Administration with control station responsibility will assemble the necessary
technical and operational information. This should be entered into the
list of Related Information (as defined in Recommendation\ M.140, \(sc\
12\ [1]) which
consists of the items shown in Annex\ A to this Recommendation.
.LP
\fB3\fR     \fBLine\(hyup procedures\fR
.sp 1P
.RT
.sp 2P
.LP
3.1
    \fILinks that involve an\fR
\fIinternational\fR \fIsingle\(hychannel\(hyper\(hycarrier (SCPC) satellite
section\fR
.sp 1P
.RT
.PP
3.1.1
The line\(hyup of such links can only be performed on a circuit
section\(hyby\(hycircuit section basis as described in \(sc\(sc\ 2.2 to\
2.4 above.
.sp 9p
.RT
.PP
3.1.2
The single\(hychannel\(hyper\(hycarrier section is lined up in
accordance with the procedures provided by the Satellite System Operations
Guide (SSOG)\ [2].
.PP
3.1.3
When dealing with circuit sections carried by satellite it should be borne
in mind that some Administrations use one polarity for transmission
whilst others use the opposite polarity. For this reason associated test
equipments normally have a normal/inverted polarity switch. It is necessary
to establish the polarity convention being used and to set the test equipment
accordingly.
.sp 2P
.LP
3.2
    \fILinks that include an international group band\fR
\fIsection\fR
.sp 1P
.RT
.PP
3.2.1
Where the international data transmission link consists
entirely of a single basic group band link, the procedures and limits given
in Recommendation\ M.910 should be used. However, it should be noted that
the terminology used in that Recommendation applies to international leased
group links, and may not necessarily apply to international data transmission
links.
.sp 9p
.RT
.PP
3.2.2
Where the international data transmission link involves a frontier crossing
basic group band link together with other types of transmission media,
the line\(hyup should be performed on a circuit section\(hyby\(hycircuit
section basis, as described in \(sc\(sc\ 2.2 to\ 2.4 above.
.PP
3.2.2.1
The frontier crossing basic group band link should be lined up in accordance
with the procedures in Recommendation\ M.910, \(sc\(sc\ 1.2 and\ 1.3 and
using the limits for the overall link given in \(sc\(sc\ 1.5 to\ 1.11 of that
Recommendation.
.PP
3.2.2.2
Remaining circuit sections may be lined up in accordance with
national practices, providing the requirements for data transmission
performance are met.
.sp 2P
.LP
3.3
    \fILinks that include an international digital section\fR
.sp 1P
.RT
.PP
3.3.1
Digital circuit sections should normally be set up and
tested in accordance with procedures and performance requirements given in
Recommendation\ M.555\ [3].
.sp 9p
.RT
.PP
3.3.2
If the digital circuit section exists wholly within the territory of a
single Administration then the national practices of that Administration
may be used.
.sp 2P
.LP
\fB4\fR     \fBData tests\fR
.sp 1P
.RT
.PP
4.1
Once the various circuit sections have been set up, lined up
and
interconnected using any necessary equipment (e.g.\ modems, transmultiplexers)
to form the overall link, the data transmission performance of the two
national sections and the international section should be separately measured
and
recorded. It should be noted that for sections routed entirely at basic
group band it will be necessary to provide interception facilities and
dedicated
modems in order to perform the data tests described.
.bp
.sp 9p
.RT
.PP
4.2
The tests and measurements should be made using an appropriate
pseudorandom bit pattern
. The bit patterns currently in use or proposed are:
.PP
4.2.1
511 bits specified in Recommendation V.52\ [4];
.LP
    2047 bits specified in Recommendation V.57\ [5];
.LP
    1 | 48 | 75 bits specified in Recommendations V.35\ [6] and
V.57\ [5].
.PP
The actual pseudorandom bit pattern to be used should be agreed
between the Administrations involved.
.PP
4.2.2
Other tests may be performed by bilateral agreement.
.sp 9p
.RT
.PP
4.2.3
As an alternative to bit error ratio (BER) tests some
Administrations prefer the use of error free seconds to measure data link
performance. Suitable test equipment is required in order to utilize this
parameter.
.PP
Administrations may use this parameter by bilateral agreement.
.PP
Care should be taken to ensure that test equipment methods and
parameters are compatible at each end of the link such that the measured
results would be identical if either equipment was used.
.RT
.sp 2P
.LP
4.3
    \fIMeasurements on national and international sections\fR
.sp 1P
.RT
.PP
4.3.1
Data test measurements should be made on the separate national and international
sections and in both directions of transmission to ensure
that each section meets the specified performance standards. A test period
of one hour for each section is desirable.
.sp 9p
.RT
.PP
\fINote\fR \ \(em\ Data test results are possibly affected by the traffic
load of the routes in question and where practicable, Administrations may
wish to take this into account when scheduling data tests.
.PP
4.3.2
Measurements of national sections should be made between the
link access points at the customer's premises and the line access points at
the terminal international centre (TIC). Additionally measurements may be
made by providing a circuit loopback at either the customer's
premises or at the TIC. This will allow checks around the loop from either
location as convenient.
.sp 9p
.RT
.PP
When an international section includes a satellite link then it
may be possible to perform\ RF loopback measurements, including the up/down
link of the satellite, if such measurements are allowed by the satellite
transponder configuration, i.e.,\ if the earth station can monitor its own
transmission. Such loopback measurements made from the customer premises,
the TIC or from the earth station should be kept for reference purposes.
.PP
Loopback measurements must be additional to unidirectional
measurements and should not be substituted for, or compared directly with,
the end\(hyto\(hyend measurements.
.RT
.PP
4.3.3
The test access arrangements should be such that no part of
the link is excluded from the test.
.sp 9p
.RT
.PP
4.3.4
The exact point of access to the link for the tests will depend
on the particular terminating equipment used on each section.
.PP
4.3.5
For the international section, measurements are made between the terminal
international centres\ (TIC).
.PP
4.3.6
For the case of a satellite single\(hychannel\(hyper\(hycarrier (SCPC)
section in which the SCPC modems provide forward error correction (FEC),
line\(hyup and maintenance measurements should normally be carried out with the
FEC facility switched out. This will ensure that the section meets basic
requirements
without protection and that the FEC facility is not masking transmission
impairments.
.PP
4.3.7
It may be necessary to switch in the FEC facility to meet the
international section and the end\(hyto\(hyend limits specified in Tables\
1/M.1370
to\ 4/M.1370, but during initial line\(hyup, it is desirable to obtain
a measure of data transmission performance with the FEC facility switched
both in and out. However, due to modem design, it may not always be possible
to obtain
measurements with the FEC facility disabled. In other cases it may be necessary
to artificially degrade the link to obtain a measure of the difference
in link performance with the FEC facility switched in and out. Measurements
and
measurement methods should be retained as benchmarks for subsequent comparisons
with results obtained during maintenance.
.bp
.PP
4.3.8
The limits that apply to the section measurements are given in
the Tables\ 1/M.1370 and 2/M.1370.
.ce
\fBH.T. [T1.1370]\fR
.ce
TABLE\ 1/M.1370
.ce
\fBLimits for bit error ratio on national or international
.ce
\fB sections\fR
.ce
\fBof international 48\(hy64\ kbit/s data transmission links | fR
.ce
\ua\d\u)\d
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(36p) | cw(96p) | cw(96p) .
Data rate (kbit/s)    Each national section    International section
_
.T&
cw(36p) | cw(48p) | cw(48p) | cw(48p) | lw(48p) .
Bit  error ratio     {
Permitted number of errors in 15 min
 }    Bit  error ratio     {
Permitted number of errors in 15\ min
 }
_
.T&
cw(36p) | cw(48p) | cw(48p) | cw(48p) | cw(48p) .
48    1 \(mu 10\uD\dlF261\u6\d    43    1 \(mu 10\uD\dlF261\u7\d    4
.T&
cw(36p) | cw(48p) | cw(48p) | cw(48p) | cw(48p) .
50    1 \(mu 10\uD\dlF261\u6\d    45    1 \(mu 10\uD\dlF261\u7\d    4
.T&
cw(36p) | cw(48p) | cw(48p) | cw(48p) | cw(48p) .
56    1 \(mu 10\uD\dlF261\u6\d    50    1 \(mu 10\uD\dlF261\u7\d    5
.T&
cw(36p) | cw(48p) | cw(48p) | cw(48p) | cw(48p) .
64    1 \(mu 10\uD\dlF261\u6\d    58    1 \(mu 10\uD\dlF261\u7\d     {
6
 }
.TE
.LP
\ua\d\u)\d
The performance limits for data transmission systems operating at bit rates above 64 kbit/s require further study.
.LP
\fINote\fR
\ \(em\ See Note to Table 4/M.1370.
.nr PS 9
.RT
.ad r
\fBTable 1/M.1370 [T1.1370], p.\fR
.sp 1P
.RT
.ad b
.RT
.ce
\fBH.T. [T2.1370]\fR
.ce
TABLE\ 2/M.1370
.ce
\fBLimits for error free seconds (EFS) on national or
.ce
\fBinternational\fR
.ce
\fBsections of international 48\(hy64\ kbit/s
.ce
\fBdata transmission links\fR
.ce
 | ua\d\u)\d
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(60p) | cw(36p) | cw(60p) | cw(60p) .
Performance  classification    Errors in 1\ second     {
Permitted percentage of measurement time
 }     {
Permitted number of seconds in measurements time
of one\ hour
 }
_
.T&
lw(60p) | cw(36p) | lw(60p) | cw(60p) .
Errored seconds    > 0    Less than 8%    < 288\
_
.T&
lw(60p) | cw(36p) | lw(60p) | cw(60p) .
Error\(hyfree seconds    > 0    More than 92%    > 3312
.TE
.LP
\ua\d\u)\d
The performance limits for data transmission systems operating at bit rates above 64\ kbit/s require further study.
.LP
\fINote\fR
\ \(em\ See Note to Table 4/M.1370.
.nr PS 9
.RT
.ad r
\fBTable 2/M.1370 [T2.1370], p.\fR
.sp 1P
.RT
.ad b
.RT
.sp 2P
.LP
4.4
    \fIEnd\(hyto\(hyend system tests\fR
.sp 1P
.RT
.PP
4.4.1
Following the satisfactory testing of the national and
international sections an end\(hyto\(hyend performance test between renter's
premises should be made. It is essential that the operational conditions
for the tests are the same as when the circuit is in service.
.sp 9p
.RT
.PP
4.4.2
The test pattern should be applied simultaneously at both of the renter's
premises and measured at the opposite ends. A minimum test period of 24\
hours should be the objective.
.bp
.PP
4.4.3
The
bit error ratio (BER)
limits to be achieved are given  in Table\ 3/M.1370. The
error free second (EFS)
limits are given in
Table\ 4/M.1370.
.ce
\fBH.T. [T3.1370]\fR
.ce
TABLE\ 3/M.1370
.ce
\fBEnd\(hyto\(hyend bit error ratio limits for the system\fR
.ce
 | ua\d\u)\d
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(42p) | cw(42p) | cw(60p) .
Data rate (kbit/s)    Error ratio    Errors in 15\ min
_
.T&
cw(42p) | cw(42p) | cw(60p) .
48    2.1 \(mu 10\uD\dlF261\u6\d    \ 90
.T&
cw(42p) | cw(42p) | cw(60p) .
50    2.1 \(mu 10\uD\dlF261\u6\d    \ 95
.T&
cw(42p) | cw(42p) | cw(60p) .
56    2.1 \(mu 10\uD\dlF261\u6\d    105
.T&
cw(42p) | cw(42p) | cw(60p) .
64    2.2 \(mu 10\uD\dlF261\u6\d    122
.TE
.LP
\ua\d\u)\d
The performance limits for data transmission systems operating
at bit rates above 64\ kbit/s require further study.
.LP
\fINote\fR
\ \(em\ See Note to Table 4/M.1370.
.nr PS 9
.RT
.ad r
\fBTable 3/M.1370 [T3.1370], p.\fR
.sp 1P
.RT
.ad b
.RT
.PP
4.4.4
It should be the objective that all 15 minute periods of the tests meet
the required bit error ratio limit. The circuit
control station
and
sub\(hycontrol station
should together consider the results of the
performance tests to decide if the circuit is acceptable for service. Thus,
one or two 15\ minute periods not meeting the standard may not preclude
the circuit from being put into service whereas a regular pattern of 15\
minute periods only just meeting the standard may indicate a need for investigation.
If such is the case, the additional parameters listed in \(sc\ 5.1 may
offer some assistance.
.PP
4.4.5
The end\(hyto\(hyend error performance objectives for a measuring
period of 24\ hours are shown in
Table\ 4/M.1370. These objectives
are based on those defined in Recommendation\ G.821, \(sc\ 2\ [7].
.ce
\fBH.T. [T4.1370]\fR
.ce
TABLE\ 4/M.1370
.ce
\fBSystem end\(hyto\(hyend error performance objectives for EFS
.ce
measurements\fR
.ce
 | ua\d\u)\d
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(60p) | cw(36p) | cw(60p) | cw(60p) .
Performance  classification    Errors in 1\ second     {
Permitted percentage of measurement time (24\ hours)
 }     {
Permitted number of seconds in measurements time
of 24\ hours
 }
_
.T&
lw(60p) | cw(36p) | lw(60p) | cw(60p) .
Errored seconds    > 0    Less than 8%    \ 6 | 12
_
.T&
lw(60p) | cw(36p) | lw(60p) | cw(60p) .
Error free seconds    > 0    More than 92%    79 | 88
.TE
.LP
\ua\d\u)\d
The performance objectives for data transmission systems operating at bit rates above 64\ kbit/s require further study.
.LP
\fINote\fR
\ \(em\ The limits presented in the tables for error\(hyfree seconds (EFS) are
based on those given in Recommendation\ G.821 | 7] and those for bit error ratio (BER) on the experience of Administrations. These limits are provisional and
are subject for further study.
.nr PS 9
.RT
.ad r
\fBTable 4/M.1370 [T4.1370], p.\fR
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.sp 2P
.LP
\fB5\fR     \fBMeasurements of other parameters\fR
.sp 1P
.RT
.PP
5.1
If after applying the procedures described or identified in
\(sc\(sc\ 2 to\ 4 the appropriate bit error ratio or error free seconds
limits cannot be met, then measurement of the additional parameters, clock
frequency, clock slip, short interruptions in transmission and buffer overflow,
may offer some indications as to why the limits are not met and to what
action should be
taken.
\v'2P'
.sp 9p
.RT
.ce 1000
ANNEX\ A
.ce 0
.ce 1000
(to Recommendation M.1370)
.sp 9p
.RT
.ce 0
.ce 1000
\fBDesignation information on international data transmission systems\fR
.sp 1P
.RT
.ce 0
.LP
A.1
    \fIDesignation\fR
.sp 1P
.RT
.PP
The designation is according to Recommendation M.140 [1], \(sc\ 11 (for
use between Administrations) or \(sc\ 3.2.15 (for private use).
.RT
.sp 1P
.LP
A.2
    \fIRelated information\fR
.sp 9p
.RT
.LP
    RI 1.
    Urgency for restoration;
.LP
    RI 2.
    Terminal countries;
.LP
    RI 3.
    Administrations', carriers' or broadcasting companies'
names;
.LP
    RI 4.
    Control and sub\(hycontrol station(s);
.LP
    RI 5.
    Fault report points;
.LP
    RI 6.
    Routing;
.LP
    RI 7.
    Association;
.LP
    RI 8.
    Equipment information;
.LP
    RI 9.
    Use;
.LP
    RI 10.
    Transmission medium information;
.LP
    RI 11.
    Composition of transmission;
.LP
    RI 12.
    (Empty item, use: \*Q\(em;\*U);
.LP
    RI 13.
    Occupancy.
.PP
The various items will be dealt with in \(sc\ 12 of
Recommendation\ M.140\ [1].
.sp 2P
.LP
    \fBReferences\fR
.sp 1P
.RT
.LP
[1]
    CCITT Recommendation \fIDesignation of international circuits,\fR
\fIgroups and line links, digital blocks, digital paths, data transmission\fR
\fIsystems and related information\fR , Vol.\ IV, Rec.\ M.140.
.LP
[2]
    Intelsat Satellite Systems Operations Guide (INTELSAT\(hySSOG).
.LP
[3]
    CCITT Recommendation \fIBringing international digital blocks, paths\fR
\fIand sections into service\fR , Vol.\ IV, Rec.\ M.555.
.LP
[4]
    CCITT Recommendation \fICharacteristics of distortion and error\(hyrate\fR
\fImeasuring apparatus for data transmission\fR , Vol.\ VIII, Rec.\ V.52.
.LP
[5]
    CCITT Recommendation \fIComprehensive data test set for high data\fR
\fIsignalling rates\fR , Vol.\ VIII, Rec.\ V.57.
.LP
[6]
     CCITT Recommendation \fIData transmission at 48 kbit/s\fR \fIusing 60\(hy108
kHz group band circuits\fR , Vol.\ VIII, Rec.\ V.35.
.LP
[7]
    CCITT Recommendation \fIError performance on an international digital\fR
\fIconnection forming part of an integrated services digital network\fR ,
Vol.\ III, Rec.\ G.821.
.bp
.sp 2P
.LP
\fBRecommendation\ M.1375\fR
.RT
.sp 2P
.ce 1000
\fBMAINTENANCE\ OF\ INTERNATIONAL\ DATA\ TRANSMISSION\ SYSTEMS\fR
.EF '%    Fascicle\ IV.2\ \(em\ Rec.\ M.1375''
.OF '''Fascicle\ IV.2\ \(em\ Rec.\ M.1375    %'
.ce 0
.sp 1P
.ce 1000
\fBOPERATING\ AT\ 48\ kbit/s\ AND\ ABOVE\fR
.ce 0
.sp 1P
.LP
\fB1\fR     \fBGeneral\fR
.sp 1P
.RT
.PP
1.1
This Recommendation describes the maintenance procedures to be applied
to international data transmission systems having aggregate bit rates of
48\ kbit/s and above.
.sp 9p
.RT
.PP
1.2
The constituent parts of some typical systems are shown in
Figures\ 1/M.1300 and\ 2/M.1300.
.PP
1.3
For some link configurations, it may be necessary to provide
modems at centres for fault location and testing purposes only.
.sp 2P
.LP
\fB2\fR     \fBFault reporting procedures\fR
.sp 1P
.RT
.PP
2.1
As far as possible, the provisions of Recommendations\ M.1012, M.1013 and
M.130\ [1] apply. Any additional special procedures must be devised by
the parties concerned.
.sp 9p
.RT
.sp 2P
.LP
\fB3\fR     \fBFault localization\fR
.sp 1P
.RT
.PP
3.1
Upon receipt of a complaint about the performance of an
international data transmission system the
control or sub\(hycontrol
station
should obtain specific assurance that all terminal equipment has
been tested and is working correctly.
.sp 9p
.RT
.PP
3.2
Unless the
control station
is already aware of some
condition which may be affecting the working of the international data
transmission system such as a major system failure or local failures involving
the link, then efforts should be made to localize and clear the fault.
.PP
3.3
It is essential that during the localization and clearance of a
fault, the control and sub\(hycontrol stations inform each other of all
relevant information and of significant actions taken which may assist
their efforts.
.PP
3.4
The purpose of the initial fault localization process is to
identify as quickly as possible whether the fault lies in either of the
.LP
national sections or the international section. The suggested sequence is
shown in diagramatic form in Figure\ 1/M.1375. This sequence is expected to
minimize the time required to locate the faulty section.
.PP
3.5
The appropriate control/sub\(hycontrol stations should arrange for
each national section to be tested between the terminal international centre
(TIC) and the access points at the renter's premises.
.PP
3.6
A data transmission performance test may be made by utilizing a
loopback at the interface with the renter's terminal equipment or by testing
from the renter's premises via a loopback at the TIC where such a loopback
facility is available. It should be borne in mind when considering the
results of such tests that the line\(hyup and maintenance limits are for
a single
direction of transmission only, so that no direct comparison with recorded
values will be possible, except where
loopback measurements
were made and recorded during line\(hyup. (See Recommendation\ M.1370,
\(sc\ 4.3.2).
.PP
3.7
When an international section includes a satellite link, then
it may be possible to perform RF loopback measurements, including the up/down
link of the satellite, if such measurements are allowed by the satellite
transponder configuration, i.e.\ if the earth station can monitor its own
transmission. Such loopback measurements, made from the customer
premises, the TIC or from the earth station should be compared with similar
loopback measurements made when the circuit functions normally.
.PP
Loopback measurements should be made before international
cooperation is sought to test the international section, but should not be
substituted for, or compared directly with, unidirectional measurements.
.bp
.LP
.rs
.sp 47P
.ad r
\fBFigura 1/M.1375, p.\fR
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.PP
3.8
Care must be taken to avoid the simultaneous operation of
loopbacks
if the system configuration is such that erroneous results would occur. Once
the need for a loopback no longer exists then care should be taken to ensure
that the link is restored and the loopback removed.
.sp 9p
.RT
.PP
3.9
If the nature of the fault report indicates that there may not
be a fault on the link but that there may be a problem with the interworking
of terminal equipment, or if the testing of the sections has not located the
fault, then end\(hyto\(hyend monitoring and testing should be performed.
.PP
The control and sub\(hycontrol stations should arrange for a
test pattern
to be transmitted in each direction from both ends of the system.
.PP
Both terminal international centres should monitor the test pattern
in both directions of transmission and advise the control station (via the
sub\(hycontrol station if necessary) of the measured error performance (
bit
error ratio
or
error\(hyfree seconds
) for each direction of
transmission.
.RT
.sp 2P
.LP
\fB4\fR     \fBOverall data circuit check\fR
.sp 1P
.RT
.PP
4.1
When the fault has been located to the international or to a
national section and has been cleared, then that section should be tested to
ensure that its bit error free second performance meets the maintenance
limits identified in \(sc\ 5.
.sp 9p
.RT
.PP
4.2
A short end\(hyto\(hyend performance test of the system should be made
to ensure that the overall limits specified in \(sc\ 5 are also met. The
actual
period of the test will depend upon the nature of the fault that has been
cleared.
.sp 2P
.LP
\fB5\fR     \fBMaintenance parameters\fR
.sp 1P
.RT
.PP
5.1
Maintenance measurements of system characteristics should
normally be evaluated by comparison with those made during the line\(hyup and
with the specified limits given in any relevant Recommendation.
.sp 9p
.RT
.PP
5.2
For measuring data transmission performance it will normally be
sufficient to check bit error ratio or error free second performance for
15\ minutes. The maintenance limits to be achieved are shown in Tables\
1/M.1375, 2/M.1375 and\ 3/M.1375.
.LP
.sp 2
.ce
\fBH.T. [T1.1375]\fR
.ce
TABLE\ 1/M.1375
.ce
\fBBit error ratio (BER) maintenance limits for
.ce
sections\fR
.ce
\fBof international data transmission systems\fR
.ce
 | ua\d\u)\d
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(36p) | cw(96p) | cw(96p) .
Data rate (kbit/s)    Each national section    International section
_
.T&
cw(36p) | cw(48p) | cw(48p) | cw(48p) | lw(48p) .
Bit  error ratio    Number of errors  in 15 min    Bit  error ratio    Number of errors  in 15 min
_
.T&
cw(36p) | cw(48p) | cw(48p) | cw(48p) | cw(48p) .
48    1 \(mu 10\uD\dlF261\u5\d    432    1 \(mu 10\uD\dlF261\u6\d    43
.T&
cw(36p) | cw(48p) | cw(48p) | cw(48p) | cw(48p) .
50    1 \(mu 10\uD\dlF261\u5\d    450    1 \(mu 10\uD\dlF261\u6\d    45
.T&
cw(36p) | cw(48p) | cw(48p) | cw(48p) | cw(48p) .
56    1 \(mu 10\uD\dlF261\u5\d    504    1 \(mu 10\uD\dlF261\u6\d    50
.T&
cw(36p) | cw(48p) | cw(48p) | cw(48p) | cw(48p) .
64    1 \(mu 10\uD\dlF261\u5\d    580    1 \(mu 10\uD\dlF261\u6\d    60
.TE
.LP
\ua\d\u)\d
The performance limits for data transmission systems operating at bit rates above 64\ kbit/s require further study.
.LP
\fINote\fR
\ \(em\ See Note to Table 3/M.1375.
.RT
.ad r
\fBTable 1/M.1375 [T1.1375], p.\fR
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.ce
\fBH.T. [T2.1375]\fR
.ce
TABLE\ 2/M.1375
.ce
\fBOverall bit error ratio maintenance limits\fR
.ce
\fBfor the system (end\(hyto\(hyend)\fR
.ce
 | ua\d\u)\d
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(42p) | cw(42p) | cw(60p) .
Data rate (kbit/s)    Bit error ratio    Number of errors in 15\ min
_
.T&
cw(42p) | cw(42p) | cw(60p) .
48    2.1 \(mu 10\uD\dlF261\u5\d    \ 910
.T&
cw(42p) | cw(42p) | cw(60p) .
50    2.1 \(mu 10\uD\dlF261\u5\d    \ 950
.T&
cw(42p) | cw(42p) | cw(60p) .
56    2.1 \(mu 10\uD\dlF261\u5\d    1060
.T&
cw(42p) | cw(42p) | cw(60p) .
64    2.2 \(mu 10\uD\dlF261\u5\d    1220
.TE
.LP
\ua\d\u)\d
The performance limits for data transmission systems operating at bit rates above 64\ kbit/s require further study.
.LP
\fINote\fR
\ \(em\ See Note to Table 3/M.1375.
.nr PS 9
.RT
.ad r
\fBTable 2/M.1375 [T2.1375], p.\fR
.sp 1P
.RT
.ad b
.RT
.LP
.sp 3
.ce
\fBH.T. [T3.1375]\fR
.ce
TABLE\ 3/M.1375
.ce
\fBOverall error\(hyfree seconds (EFS) maintenance limits for the
.ce
\fBsystem (end\(hyto\(hyend)\fR
.ce
 | ua\d\u)\d
.ce
(Provisionally the limits contained in the table apply to all
.ce
measurements
.ce
whether made on a section or end\(hyto\(hyend basis)
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(60p) | cw(36p) | cw(60p) | cw(60p) .
Performance  classification    Errors in 1\ second     {
Permitted percentage of measured time (15\ minutes)
 }     {
Permitted number of seconds in
15\ minute period
 }
_
.T&
lw(60p) | cw(36p) | lw(60p) | cw(60p) .
Errored seconds    > 0    Less than 8%    \ 72
_
.T&
lw(60p) | cw(36p) | lw(60p) | cw(60p) .
Error\(hyfree seconds    > 0    More than 92%    828
.TE
.LP
\ua\d\u)\d
The performance limits for data transmission systems operating at bit rates above 64\ kbit/s require further study.
.LP
\fINote\fR
\ \(em\ The limits presented in the tables for error free seconds (EFS) are
based on those given in Recommendation\ G.821\ [2] for bit error ratio on the
experience of Administrations. These limits are provisional and are subject for further study.
.nr PS 9
.RT
.ad r
\fBTable 3/M.1375 [T3.1375], p.\fR
.sp 1P
.RT
.ad b
.RT
.LP
.sp 2
.sp 2P
.LP
    \fBReferences\fR
.sp 1P
.RT
.LP
[1]
     CCITT Recommendation \fIOperational procedures in locating and clearing\fR
\fItransmission faults\fR , Vol.\ IV, Rec.\ M.130.
.LP
[2]
    CCITT Recommendation \fIError performance on an international digital\fR
\fIconnection forming part of an integrated services digital network\fR ,
Vol.\ III, Rec.\ G.821.
.LP
.bp