Digital Line Interface Unit (DLIU)

TM 11-5895-1012-10

the coordination of test fault isolation, or operational

test set is used to measure signal levels, noise level and

activities. Inputs to the monitor page printers are

volume units (VU). The test set usually has a number

usually in the neutral mode. The output of the trans-

filters for the inputs.

mitting keyboard consists of dry contacts. The loop

Balance Test Set. The terminal balance

into which this output is inserted requires the applica-

test set when provided* allows for connecting and

tion of operating battery from an external source. The

switching instruments required for each test without

printers and keyboards may be used in circuit operat-

changing patch cords to the circuits to be tested.

ing at 60, 75, or 100 words per minute when appropri-

h. Wave Analyzer Test Set. The wave analyzer test

ate speed change gears are used. A monitor teleprinter

set provides amplitude and frequency information

converter panel is usually provided which will allow

over a given band of frequencies. The test set can

the monitor teleprinter to be used without interupt-

separate frequency components of an input signal by

ing the circuit being tested. The converter permits the

means of selectable bandwidths and tuning controls.

insertion of the page printer into dc monitor jacks by

i. Patter Generator. The pattern generator is used

converting low level voltage variations into current

to generate a wide variety of telegraph teat signal pat-

impulses needed to drive the page printer.

terns having predetermined and controllable charac-

p. Dual Meter Panels. The meter panel usually con-

teristics and parameters. The unit is used in conjunc-

tains a high impedance voltmeter and low impedance

tion with data measuring equipment to test and evalu-

milliammeter. The milliammeter is used to measure

ate the performance of data/TTY systems or equip

the telegraph loop current (high level). Loop current is

ment.

measured by patching the meter input into a LINE

j. Singing Point Test Set. The singing point test set

MON or EQUIP MON jack at the equal level dc patch

measures the singing margin of 4-wire transmission

circuits using hybrid terminations by inserting a varia-

bays.

q. Low Led Meters. These meters, mounted over

ble, but known, gain into the circuit until oscillation

various dc patch bays, provide a low level voltage read-

occurs. The test set may also be used as a variable gain

ing when patched into the monitor jack of a dc circuit

amplifier with a maximum undistorted output of

usually 0 dBm at 600 ohms.

via the miscellaneous patch panel. The meters usually

k. Impulse Noise Counter. The impulse noise count-

have a zero center scale, with 15 vdc full deflection.

r. Reference Tone Generator. The reference

er counts the number of impulses exceeding a number

of different selected levels for a selected length of

generator provides 0, - 10, -8.7, and - 12.7 dBm

time. The unit provides a readout for each selected lev-

tone levels (or others depending upon the man

turer) to the patch and test bays. These test tone levels

el, each giving the number of times an impulse exceeds

make jack appearances on the miscellaneous patch

the associated adjusted level.

panels and then distributed to each patch and test bay.

l. Phase Jitter Measuring Set. The phase jitter

measuring set measures the peak to peak phase jitter

2-39. Digital

Line Interface Unit (DLIU)

indegrees.

m. Transmission Delay

The digital line interface unit is a solid state plug-in

transmission delay measuring test

printed circuit module for use as a line isolator and

transmitter and a receiver which is used to measure

level converter generally located between the primary

signal delay and amplitude versus frequency.

dc and equal level dc patch bays. It accepts a high

n. Data Analysis. Data analysis test sets provide the

level, neutral or polar, or low level signal and converts

capability for comprehensive analysis and generation

it to low level, polar and vice versa. The unit usually

data, start, stop data, and

te with either synchronous or start-stop data

up to 2400 baud. Automatic adjustable loop

nitor teleprinters are

current regulation for high level output lines is pro-

used to monitor teleprinter traffic in dc telegraph

vided as well as no transition/open loop detection and

loops. A transmitting keyboard is usually included

alarm, build-in loop battery fusing, and output moni-

which, in conjunction with one of the page printers

tor jack and self contained power supply for inter-cir-

and utilizing a spare dc circuit, may be used in com-

cuit operation.

municating between Technical Control Facilities for

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