The traffic monitor signal

TM 11-5820-695-35

transistor Q15 and turns on transistor Q16 providing the

input of operational amplifier AR1 is pin 2 and the

normal (green) indication. When electrical frequency

noninverting input is pin S. The output signal is taken

synthesizer 2A14 is not phase locked, the input signal

from pin 7 with a feedback resistance connected from

drops to zero volts which turns on transistor Q15

the output pin 7 to the inverting input pin 2 to establish

producing the alarm (red) indication.

the gain of the amplifier AR1.

c. The traffic monitor signal is coupled in pin 13

e. The carrier (if) monitor signal is applied to the

through attenuator R1-R3 to the inverting input pin 2 of

base of transistor Q4 and the carrier (if) monitor

amplifier AR1. The network consisting of C1 and R4

reference signal (a predetermined level) is applied to the

connected across the differential inputs (pin 2 and 3)

base of Q3. Transistors Q3 and Q4 on board A5 (fig. 2-

provides lag compensation which increases the high

14(1)) form a differential amplifier. As the 70 MHz if

frequency response. The amplified traffic signal is

carrier input to 2A5 increases, the age signal decreases,

applied through the peak detector circuit consisting of

consequently, the carrier (if) monitor input to Q4

capacitor C4, diodes CR1 and CR2 and capacitor C5 to

decreases. With the input to Q4 lower than the input to

the meter selector switch on 2A15A2 through variable

Q3, Q3 will conduct more heavily and Q4 turns off.

resistor R8 and also to the base of emitter follower stage

With Q4 turned off, its output dc voltage is high. The

Q1. The positive peak-detected dc voltage is applied to

high output of Q4 is applied through potentiometer R35

Q1 which couples the signal through attenuator network,

on board A1 (fig. 214(3)) to Schmitt trigger (Q17, Q18)

R10, R11, and R12, to its associated Schmitt trigger

on board A5 (fig. 2-14(3)). Potentiometer R35 is used

circuit on board AS. The Schmitt trigger circuit for the

to set the input level to Q17. The high output from Q4

traffic signal consists of transistors Q5 and Q6 (fig. 2-

causes Q17 to turn on, which in turn, causes Q18 to turn

14(2)).

When no signal is present, transistor Q6

off and Q19 to turn on. With Q19 turned on, its collector

conducts and holds transistor Q5 off due to the voltage

is at a low level which provides a low impedance path to

developed across common emitter resistor R48. The

ground to light the normal (green) if carrier indicator

incoming peak-detected traffic signal will forward bias

lamp on 2A15A2. The inverted output level at the

transistor Q5 when the magnitude of the peak-detected

collector of Q18 is applied to the alarm (red) carrier (if)

traffic signal exceeds the magnitude of the voltage

indicator on 2A15A2 which provides a low impedance

developed across common emitter resistor R48. When

path to ground for the alarm indicator when the carrier

this occurs transistor Q5 conducts and transistor Q6 cuts

(if) monitor input (derived from the age signal) is at a

off until the peak-detected signal again drops below the

higher level than the predetermined carrier (if) monitor

voltage level of the common emitter resistor R48. The

reference signal.

output of the Schmitt trigger circuit is a positive voltage

which is developed at the collector of transistor Q6.

f. A three input diode OR-gate and inverting

This voltage is applied to the base of transistor Q7 to

transistor provides the summary alarm function. This

forward bias it into conduction. When transistor Q7 is

circuit consists of diodes CR12, CR15, and CR16,

conducting its collector is at a low level; this provides a

transistor Q23 and resistors R102 and R103 (fig. 2-

low impedance path to ground to light the normal

14(2)). When the anode of any input ,diode has a

(green) TRAF indicator lamp on meter panel assembly

positive voltage level applied to it, it conducts and

2A15A2. The inverted output level at the collector of

forward biases transistor Q23 into conduction producing

transistor Q6 is applied to the alarm (red) TRAF

a summary alarm condition. When all of the diodes

indicator lamp on 2A15A2. Transistor (Q7) provides a

have a low (or zero) voltage applied to their anodes,

low impedance path to ground for the alarm lamp when

they are nonconducting and transistor Q23 is turned off

no traffic signal is detected (quiescent state of the

producing a normal indication.

Schmitt trigger circuit).

g. Zener diodes C5 and CR6 are incorporated on

d. A synthesizer monitor signal, developed in

board A1 to provide regulated plus and minus voltages

electrical frequency synthesizer 2A14, is applied to

for the integrated circuits. Zener diode CR5 (fig.

Schmitt trigger circuit Q14 and Q15 through pin P2-17

214(8)),

conjunction

with

resistor

(fig. 2-14(2)). This signal indicates when the electrical

frequency synthesizer 2A14 is not phase locked and is

in a search mode attempting to correct the oscillator

frequency. When electrical frequency synthesizer 2A14

is phase locked, a +2 volt level is applied to input pin 17

to forward bias transistor Q14. This in turn, cuts off

2-117