LINEAR MODULATION

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

LINEAR MODULATION

2-6. (Refer to figure FO-5.) Linear modulation is developed by a con scan

generator located on circuit cards 1A3A1/1A4A1 and 1A3A2/1A4A2. This generator

develops an audio sinewave which drives the linear modulator to amplitude

modulate the RF signal.

(1) The CON SCAN FREQUENCY SELECT S2 is a two decade thumbwheel switch which

selects the con scan frequency in 1 Hz steps from 1 Hz to 99 Hz.

(2) CLOCK GENERATOR Y1 (U15) is a 10 MHz oscillator which feeds countdown

(3) The output of countdown circuit is a 500 KHz clock which steps the

interval counter U24, U12, U14.

(4) The MAGNITUDE COMPARATOR U34, U22, U13 compares the frequency select

data with the count in the interval counter. When a comparison occurs

the digital con scan generator U7, U8, U9, U39 is loaded and the inter-

val counter is reset.

(5) The output of the DIGITAL CON SCAN GENERATOR is in 8-bit parallel

binary form. The D/A Converter U1 changes the digital data to a

triangle wave.

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