Analog Circuits

TM 11-6625-2884-30/NAVAIR 16-35TS3615-2

RF MODULATION (Continued)

Analog Circuits

CON SCAN FREQUENCY SELECT SWITCH S2 is a two decade thumbwheel switch

(1)

which selects the con scan frequency from O-99 Hz.

PULSE GENERATOR 1A3A1/1A4A1 contains a clock generator, counters, com-

(2)

parators, digital con scan generator and a D/A converter which produce

a triangle wave at the preset frequency of the con scan frequency select

switch S2.

The digital con scan generator provides the CON SCAN SYNC at the zero

(3)

crossover of the triangle wave at front panel jack SYNC-CS J5.

CON SCAN SHAPER and PULSE CONTROL 1A3A2/1A4A2 receives the triangle wave

(4)

and shapes it into a sinewave. The depth of modulation of the sinewave

is controlled by CON SCAN MODULATION DEPTH SWITCH S6, adjustable from

O-25 dB.

The sinewave output of the shaper is amplified and sent to LINEAR

(5)

MODULATOR CR3.

The sinewave output of the shaper is also directed to CS MONITOR jack

(6)

J9. Jack J9 connects to BTS VIDEO on the Status Panel 1A2 to be

monitored by the oscilloscope.

PULSE MODULATION TO PIN SWITCH CR2. PRI Selector Switch S7 selects on

(7)

of three preset PRI's A-W, A-F, B, or a variable PRI set by the PRI

select switch S5.

VARIABLE PRI Select Switch is a three decade thumbwheel switch with a

(8)

range of 300 to 999 microseconds.

PATTERN SYNC signal is developed from a threat decoder and PROM address

(9)

register. It is used to sync the oscilloscope when the preset PRI's

A-W/A-F/B are selected.

(10)

PRI DATA is developed from programmed ROM's and pulse control circuitry

for controlling the PRI generator on the pulse generator card.

(11)

When PRI data (interval between two pulses) is received at the pulse

generator an advance address signal is sent to the con scan shaper and

pulse control card to set up the next PRI.

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