DCS Technical Schedules

TM 11-5895-1012-10

nical Control Facilities should determine distortion

formance requirements when the isochronous distor-

thresholds for the particular equipment and circuits

tion of the input data is less than or equal to 10

with their station and forward recommendations to

percent measured at the data signaling rate of the

appropriate DCA field activities for concurrence, with

modem. The isochronous distortion of the output data

an information copy to appropriate Operation and

signal when measured at the operating data signaling

Maintenance activities. When distortion thresholds

rate shall be less than four percent.

are exceeded, the technical controller will initiate cor-

j. Digital Regenerative Repeaters.

rective action to remove the equipment from service.

(1) Synchronous repeater input will accept the fol-

For example, when the maximum output distortion al-

lowing distortion limits and provide an output signal

lowed on a transmitter-distributor (out-of-service) is 1

with not more than three percent distortion, of which

percent, corrective action will be initiated when the

not more than one-third (one percent) is bias:

output distortion exceeds 4 percent. Corrective action

(a) Total peak distortion: 49 percent.

may include changing transmitter-distributors, repair-

(b) Bias distortion: 49 percent.

ing equipment on line, or using a spare circuit.

(C) Cyclic distortion: 49 percent.

b. Equipment Capability. If the design capability of

(d) Fortuitous distortion: 49 percent.

equipment listed in subsequent paragraphs permits

(2) Start-stop repeater input will accept the

operation at maximum distortion limits lower than

following distortion limits and provide an output

those specified, the maximum limits specified in the

signal with not more than three percent distortion, or

technical manual or manufacturer handbook will

which not more than one-third (one percent) is bias:

apply.

(a) Total peak distortion: 49 percent.

c. VFCT. With the transmit and receive terminals

(b) Bias distortion: 49 percent.

connected back-to-back, sending and receiving loops

(c) Cyclic distortion: 24.5 percent.

properly terminated, and all transmit tones at proper

(d) Fortuitous distortion: 24.5 percent.

levels, random undistorted signals will be keyed simul-

k. Punched Card Readers. Punched card readers

taneously into each sending loop at the maximum

will produce not more than one percent distortion of

modulation rate of the terminal design. The maximum

the signal element for electronic devices and 3.5

distortion measured in the receiving loops will not

percent distortion for electromechanical devices, as

exceed 4 percent total peak telegraph distortion at

measured in relation to the theoretically correct unit

modulation rates up to and including 75 baud.

interval duration.

d. Transmitting Equipment Output Distortion. The

l. Card Punch. The card punch will operate without

output distortion (all types) of electromechanical, elec-

error if the input distortion is less than the following:

tronic, or composite transmitting devices (either

(1) Total peak distortion: 49 percent.

sequential or coincidental selection) will not exceed.

(2) Bias distortion: 49 percent.

one percent.

(3) End distortion: 49 percent.

e. Electromechanical Receiving Devices. Electrome-

(4) Cyclic distortion: 24.5 percent.

chanical receiving devices shall be capable of tolerat-

m. Magnetic Tape Readers. Total distortion attrib-

ing signal distortion as follows:

utable to the magnetic tape reader will not exceed one

(1) Total peak distortion:45 percent.

percent at the output of the intermediate equipment.

(2) Bias distortion: 45 percent.

n. Magnetic Tape Recorders. Magnetic tape re-

(3) End distortion: 45 percent.

corders will operate without error if the input distor-

(4) Cyclic distortion 22.5 percent.

tion is less than the following:

f. Electronic-Input Receiving Devices. Receiving de

(1) Total peak distortion: 49 percent.

vices utilizing electronic input circuitry shall be

(2) Bias distortion: 49 percent.

capable of tolerating signal distortion as follows:

(3) End distortion: 49 percent.

(1) Total peak distortion: 49 percent.

(4) Cyclic distortion: 24.5 percent.

(2) Bias distortion: 49 percent.

o. Paper Tape Readers.

(3) End distortion: 49 percent.

(1) Electromechanical Equipment. The total out-

(4) Cyclic distortion: 24.5 percent.

put distortion will not exceed one percent for the

g. Electromechanical Polar Relays. Total distortion

standard 5-unit code character interval, and 3.5 per-

introduced into the transmission facilities, attributa-

cent for the standard 8-unit code character (ASCII).

ble to the relay, shall be less than two percent.

(2) Equipment Incorporating Electronic Output

h. Electronic Polar Relays. Total distortion intro

Circuitry. The total output distortion will not exceed

duced into transmission facilities, attributable to the

one percent.

relay, shall be less than one percent.

p. Paper Tape Punches. Electromechanical paper

i. Differential Phase Shift Keying (DPSK) Modems.

tape punches incorporating electronic serial input cir

DPSK modems &all operate in accordance with per

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