Examples of Voice Channel Fault Isolation Procedures

TM 11-5895-1012-10

(a) Check the level of the multichannel VFCT

tones at the voice frequency patch panel and instruct

(3) Telephone numbers.

(4) Date, time and trouble number.

(4) When the trouble has been isolated and cor-

(5) Station reported to.

rected by coordinating the maintenance necessary to

(6) Names or initials of

coordinator.

restore operations, notify the distant Technical Con-

d. Inquiries concerning

status of reported

troller of the nature of the problem and restore the

user circuits to normal.

carrier will provide information as

concerning the status of the circuit

(5) If the malfunction cannot be corrected in a

reasonable length of time (Le., 10 minutes), the Tech-

The commercial carrier may include probably location

nical Controller should notify the appropriate DOCC

of trouble switch to an alt-route, but they are not

and, if required, request rerouting instructions for pri-

required to furnish more detailed information. Only

ority channels pending the completion of repairs.

information concerning restoral of circuit or in-effect

between the commercial

(6) Complete station records, trouble reports, log

entries, etc., in accordance with established proce-

dures.

4-35. Examples of Voice Channel Fault

Isolation Procedures

4-34. Commercial

Procedures

Initial testing will be conducted to determine whether

There are a number of acceptable methods of isolating

the reported trouble is in the local terminal portion,

a faulty link in a communications channel. Two meth-

distant terminal portion, or in the leased portion of the

ods are explained in this paragraph . The first method

(discussed in a and b below) requires the isolation pro-

circuit. So that such testing can be accomplished, it is

cedure to begin at the point of fault recognition. Each

essential that all parties concerned definitely under-

site clears itself of any responsibility for fault by

stand the extent of their responsibility.

a. Military terminals are responsible for establish-

ing proper circuitry, correct operation of equipment

sponsible TCF to isolate the fault over the whole com-

and circuitry from and to the terminals where the

munications chain by having the signal from the local

commercial carriers responsibility begins at the inter-

TCF looped back and tested at various points in succes-

face points.

sion along the chain

b. The commercial carrier is responsible for estab-

a. Noise Burst on Multiplexed Through Circuit. The

lishing and maintaining the type of service requested

procedure followed is outlined in flow-chart fashion in

by the military between the designated terminals. This

tant Technical Controller is notified

figure 4-7. Th

includes troubleshooting and restoration of service up

that noise bursts are being received by a subscriber.

to the interface points. The following action will be

The complaint has been verified at the distant end,

taken:

and that station has been cleared of causing the

(1) Call the appropriate commercial circuit control

trouble. The noise bursts are incoming to the distant

office for trouble reporting.

Technical Control Facility, and that Technical Con-

(2) Provide an account of the trouble indicated ac-

troller requests that the local Technical Controller

cording to results obtained from tests.

clear the local station of being the cause of the noise

(3) The nature and indications of common

bursts. The local controller is responsible for simply

troubles encountered on leased or military circuits are

checking the circuit through the site to determine if

listed below. The terms listed have been chosen so that

the fault source is in the station, reporting back to the

the nature of the trouble will be understood by com-

distant station, and correcting the fault if necessary.

mercial carrier personnel throughout the world who

Following is an example of an isolation procedure for

have contact with the DCS.

this type of fault:

(a) No receive current or signal.

(1) At the equal level patch panel farthest from

(b) Cannot receive ringing current.

the complaining subscriber, connect a loudspesker to

(c) Levels too low.

the receive monitor jack of the affected circuit.

(d) Excessive noise.

(2) Listen for the noise burst complaint.

(e) Intense crosstalk.

4-20