Section IV. FAILURES AND FAULT ISOLATION

TM 11-5895-1012-10

patching is accomplished at both the equal level dc and

transferred to the tail segment cable pair for spare

primary dc patch panels. Since the patch panels are

channel 2. This patch is made at the primary dc patch

normally physically separated, two Technical Con-

panel (fig. 2-15) and the Patch and Test Facility, or

trollers are needed to perform the operation with

similar patching facility, at the other end of the cable.

minimum interference to the user. The procedure

The patching operations are the same at both ends of

described below it the same at both patch panels.

the cable. Only the patching operation at the TCF is

(1) At the primary dc patch panel, place two patch

cord plugs loosely into channel 1 REC LINE and

covered below.

(1) Place two patch cord plugs loosely into the

TRANS LINE jacks. Place the plugs on the other end

channel 2 REC LINE and TRANS LINE jacks

of the patch cores loosely into channel 2 REC EQU and

(2) Place the plugs on the other end of the patch

TRANS EQU jacks respectively.

cords loosely into the channel 1 REC EQU and TRANS

(2) At the equal level dc patch panel place the

EQU jacks respectively.

patch cord plugs loosely into the channel 1 REC LINE and

(3) Establish voice contact between the TCF and

TRANS LINE jacks. Place the plugs on the other end

of the cords loosely into channel 2 REC EQU and

PTF.

(4) The Technical Controller will take charge, and

TRANS EQU jacks respectively.

on a prearranged signal, usually the count-of-three, all

(3) Establish voice contact between the two patch

loose plugs are set into the jacks simultaneously.

panels. On the count-of-three, all loose plugs are set

into the jacks simultaneously.

Section IV. FAILURES AND FAULT ISOLATION

4-22. General

All service interruptions must be logged, regardless of

period of outage.

a. All transmission media with breakout capability

entering a DCS Station appears on the jack fields in

4-24. fault Isolation

the Technical Control Facility for control and restoral

Fault isolation is the process of determining the loca-

tion of a trouble within a circuit, or within the trans-

b. The Technical Controllers are responsible for all

mission media which carries the circuit The trouble

transmission media entering, terminating or transit-

could be in any of the transmitting facilities of one sta-

ing a DCS Station.

tion, the receiving facilities of the adjacent station, the

(1) All traffic will be stopped where practicable

media connecting them, or the user's equipment which

before any action is taken that will interrupt its flow.

terminates the circuit. After the general area of a

When actions can be predicted; e.g. scheduled main-

trouble has been isolated; e.g. media, user equipment,

tenance, the user will be notified in advance in order

access lines, etc., a decision can be made to provide the

that traffic may be stopped at the scheduled time.

quickest method of restoral. Fault isolation is not a

(2) Occasionally, traffic will be interrupted due

finger-pointing or blame-fixing exercise. The basic

to unforeseen events, such as transmission media

purpose is to locate the source of a trouble and get it

degradation or equipment failure, Traffic may also be

fixed, regardless of where it is, or which piece of equip

interrupted by preemption of the circuit to restore a

ment is at fault. The same problem recurring at fre-

higher priority user. In all such cases, the user will be

quent intervals is of prime concern to both DCA and

notified of the transmission media failure or preemp-

the operation and maintenance agency, and corrective

tion to permit them to stop traffic and maintain con-

measures must be taken. However, this is a by-

tinuity.

product, not the purpose of fault isolation.

4-23. Circuit Outages

a. The first step in fault isolation is the recognition

The Technical Controller is responsible for identifica-

that a problem exists. On the surface, fault recognition

tion of all outages or interruptions on the circuit. Tech-

may seem to be a trite statement. However, the major-

nical Controllers are also responsible for restoration of

ity of problems are the result of someone failing to

service with minimum loss of operating time. Con-

recognize that trouble signs are appearing. Trouble

trollers will test, monitor, and observe outgoing and

recognition may be a result of quality control testing,

incoming circuits and channels to ensure proper opera-

equipment sensors and alarms, customer complaint, or

tion. They will coordinate with distant stations and

any combination of these. The main point is that when

local users, as necessary to isolate the report troubles.

the trouble signs appear, regardless of how or from

4-12