Radio Traffic Normal

TM 11-5820-695-35

1RRPFAIL is logic one (failure of radio repeat pcm

nals from IA12A8 (IRRIFAIL), 1AL1A9 (1RCFAIL),

signal), the output of A2C is low. When there is no

IA12A10 (1RPFAIL), and 1A12A4 (1RRPFAIL); and the

functional failure, 1.RRPFAIL is logic zero 'and A2C

radio traffic failure signal (1FRFAII,) from 1A12A8. The

applies a high to A9. When Radio Set AN/ARC-144 is

functioning of these signals is similar to that described

not in radio repeater mode, signal ORRM is logic one,

for cable-to-radio circuits (para 2-5f). That is, since the

and A2C then always applies a high to A9. With all

radio pcm signal is processed in sequence through the

input signals high, the output of A9 is low and A4A has a

indicated circuits, a functional failure in any plug-in

low at pin 1. The low output of A9 is inverted to a high

module causes that module and any modules following

by inverter A7E, so A4B has a high at pin 6 and A1A

it in the processing sequence to activate the functional

has a high at pin 13.

failure signal. Likewise, when the radio pcm signal

(FRPCM) fails, all functional failure signals are

(4) Functional Failure. When a functional

activated. The radio-to-cable circuits use these signals

failure occurs, the output of at least one inverter '(A8A,

to distinguish which kind of failure has occurred,

A8B, A2C, or A8E) switches to low and the output of A9

functional or radio traffic failure.

is then high. The output of A9 is also-high without a

(1) Radio Traffic Normal. When radio traffic

functional failure if the CABLE LOOP TEST switch is

is normal, signal I'FRFAIL (from 1A12AS) is logic zero

placed in TEST position. In either case, A4A has a high

and the output of inverter A8D is high. Relay driver

at pin 1. The high from A9 is inverted by A7E, so A4B

transistor Q7 is turned on land output signal 1BPOW is

has a low at pin 5 and A1A has a low at pin 18.

at logic zero. The output signal (high) from A8D is

(5) Radio Traffic Normal No Functional

inverted by negative OR gate A4D (input pin 12 of A4D

Failure. When radio traffic is normal and there is no

is always high from switch S1A) and inverted again by

functional failure, the conditions of (1) and (3) above

A7D. Negative OR gate A1A, therefore, has a high

exist and operation is as follows:

input at pin 1, negative OR gate A4B has a high input at

(a) A4A a high at pin 2 and a low at pin

pin 6 and NAND gate A4A has a high input at pin 2.

1 and its output is high. Lamp driver Q1 is turned on

(2) Radio Traffic Failure. When loss of the

and signal 1RFFL is logic zero. The high output of A4A

radio traffic signal occurs, signal LFRFAIL is logic one

is inverted to low by A3A, and lamp driver Q2 is turned

and the output of inverter A8D is low. Relay driver

off. Signal ORFFL is logic one and the RADIO TO

transistor A7 is turned off and output signal 1BPOW is

CABLE MODEM indicator is lighted green.

at logic one. Signal 1;BPOW is connected to orderwire

(b) A4B has a high at both inputs and

assembly IA,13 and, when it is a logic one, activates a

its output is low. Lamp driver Q3 is turned off and signal

relay which causes the from radio (FRPCM) signal to be

ORTFL is logic one. The low output ,from A4B is

applied directly to orderwire assembly 1A13 instead of

inverted by ASB and lamp driver Q4 is turned off.

through digital data modem l'A12. This connection

Signal IRTFL is logic zero and the traffic out indicator is

allows orderwire communications to be maintained when

lighted green.

the radio pcm signal is lost. The output signal (low)

from A8D is inverted first by A4D, and inverted again by

1. If there is no failure in the cable-to-radio circuits, the

A7D. Negative OR gate A1A, therefore, has a low input

output of NAND gate A2B is high (para 2-5f(5)) so A1A

at pin 1; negative OR gate A4B has a low input at pin 6,

has a high at pins 2 and 3. With all inputs high, the

and NAND gate A4A has a low input at pin 2.

output of A1A is low and this is Inverted to high by ASD.

(3) No Functional Failure. When there is no

Transistor Q5 is turned on, Q6 Is turned off and signal

functional failure, the output signal of inverters A8A,

OMARY is high (no alarm).

A8B, A2C and A?: ' are all high and the corresponding

(6) Radio Traffic Normal-Functional Failure.

inputs at negative OR gate A9 are high. The inputs to

When radio traffic is normal and there is a functional

A9 from ASC and A8F are always high; A8C and A8F

failure, the conditions of (1) and (4) above exist and

are not used. The signal at pin 3 of A9 is always high

operation is as follows:

except when the CABLE LOOP TEST switch is in TEST

position. When Radio Set AN/GRC144 is being used in

the radio repeater mode, input signal ORRM is logic

zero. This signal is .inverted to logic one (high) by

inverter A2D, and applied to AND gate A.2C. Then if

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