Alarm-Monitor LA12At Asynchronous Mode

TM 11-5820-695-35

(1FRFAIL) from 1A12A8. The functioning of these

signals is similar to that described for cable-to-radio

(a) Both inputs to A4A are high and its

circuits (para 2-5f). That is, since the radio pcm signal

output is low. Lamp driver Q1 is turned off and signal

is processed in sequence through the indicated circuits,

IRFFL is logic one. The low output of A4A is inverted to

a functional failure in any plug-in module causes that

low by A3A and lamp driver A2 is turned on. Signal

module and any modules following it in the processing

ORFFL is logic zero. The RADIO TO CABLE MODEM

sequence to activate the functional failure signal.

indicator is lighted red.

Likewise, when the radio pcm signal (FRPCM) fails, all

(b) The inputs to A4B are high at pin 6

functional failure signals are activated. The radio-to-

and low at pin 5. The output, therefore, is high. Lamp

cable circuits use these signals to distinguish which kind

driver Q3 is turned on and signal ORTFL is logic zero.

of failure has occurred, functional or radio traffic failure.

The high output from A4B is inverted by A3B and lamp

(1) Radio Traffic Normal. When radio traffic

driver Q4 is turned off. Signal 1RTFL is logic one. The

is normal, signal 1FRFAIL (from 1A12A8) is logic zero

traffic out indicator is lighted red.

and the output of inverter A6F is high. Relay driver

transistor Q7 is turned on and output signal 1BPOW is

from A7E, when a radio-to-cable functional failure

at logic zero. NOR gate A8A has a high input at pin 1,

exists, or low at pin 2 and 3, from A2B, when a cable-to-

NOR gate A3D has a high input at pin 12'and NAND

radio functional failure exists (para 25f(6)). The output

gate A3C has a high input at pin 9.

of A1A is high and this is inverted to low by A3D.

(2) Radio Traffic Failure. When loss of the

Transistor Q5 is turned off, transistor Q6 is turned on,

radio traffic signal occurs, signal IFRFAIL is logic one

and signal OMARY is low (alarm condition).

and the output of inverter A6F is low. Relay driver

(7) Radio 7raffic Failure. When a radio traffic

transistor A7 is turned off and output signal 1BPOW is a

failure occurs (loss of the FRPCM signal), all functional

logic one. Signal 1BPOW is connected to orderwire

failure signals are also affected and switch to logic one

assembly LA13 and, when it is a logic one, activates a

(high). The conditions of (2) and (4) above then exist

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

and the relay driver circuit is activated as explained in

applied directly to orderwire assembly 1A13 instead of

(2) above. Other operation is as follows:

through digital data modem 1A12. This connection

(a) The input signals to A4A are low at

allows orderwire communications to be maintained when

pin 2 and high at pin 1 and its output is high. Otherwise,

the radio pcm signal is lost. NOR gate A8A has a low

operating conditions are as explained in (5Xa) above.

input at pin 1; NOR gate A3B has a low input at pi

(b) Both inputs to A4B are low and its

12, and NAND gate A3C has a low input at pin 9.

output is high. Otherwise, operating conditions are as

(3) No Functional Failure. When there is no

explained in (6)(b) above.

functional failure, the output signal of Inverters A5A,

A5B, A3B and A5C are all high and the corresponding

output is high. Otherwise, operation is as explained in

inputs at NOR gate A4 are high. The signal at pin 3 of

(6Xc) above.

A9 is always high except when the CABLE LOOP TEST

(8) Switch S1. Alarm monitor 1A12A6 also

switch is in TEST position. When Radio Set ANIGRC-

contains switch S1 which is not used. Section SIC lights

144 is being used in the radio repeater mode, input

lamp DS1 when the switch is placed in the TEST

signal ORRM is logic zero. This signal Is inverted to

position; but the lamp has no function. Section SlA

logic one (high) by inverter A3A, and applied to NOR

applies +5V to A4D in either NORMAL or TEST position.

gate A3B. Then if IRRPFAIL is logic one (failure of

radio repeat pcm signal), the output of A3B is low.

i. Alarm-Monitor LA12At Asynchronous Mode.

When there is no functional failure, 1RRPFAIL is logic

(fig. 5.1 and 533.1). The radio-to-cable circuits of alarm

zero and A3B applies a high to A4. When Radio Set

monitor

2A control the RADIO TO CABLE MODEM

AN/GRC-144 is not in radio repeater mode, signal

indicator on meter panel assembly 1A16A4 and the

ORRM is logic one, and A3B then always applies a high

shelter mounted traffic out indicator. Two kinds of

to A4. With all input signals high, the output of A4 is low

signal are monitored by the radio-to-cable circuits:

and A3C has a low at pin 8. The low output of A4 is

functional alarm signals from 1A12A8 (1RRIFAIL),

inverted to a high by

1A12A9 (1RCFAIL), U2A126 (IRPFAIL), and 1A12A4

(1RRPFAIL); and the radio traffic failure signal

Change 2 2-23