PULSE MODULATED

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

PULSE MODULATED

2-5. (Refer to figure FO-4.) The pulse modulation circuits are located on

CCA, CS and Pulse Control 1A3A2/1A4A2 and CCA, Pulse Generator 1A3A1/1A4A1.

(1) PRI SELECT SWITCH S7 is a four position rotary switch which selects the

PRI pattern for the Pulse Generator. Three positions of the switch

select one of three preset PRI's. The switch position and threat codes

are as follows:

S7-Switch Position

Threat Code

A-W

A-F

VAR PRI

The other position of the switch selects a variable PRI controlled by

VARIABLE PRI Switch S5.

THREAT DECODER. The threat decoder consists of two programmed micro-

(2)

circuits U9, U29. Each PROM contains 32 words, each word contains 8

bits of data. The two PROM's make up a 16 digit word. The first word

addresses the A-W mode, the second word addresses the A-F mode and the

third word addresses the B mode. The information from the threat

decoder is loaded into the PROM address counter U8, U18, U28.

A-W/A-F/B PROM'S. The PROM address counter addresses the A-W/A-F/B

(3)

PROM's, Each mode contains 4 PROM'S. Each PROM contains 512 words.

Each word contains 4 bits of data.

A-W PROMS U23, U6, U16, U26

A-F PROMS U13, U5, U15, U25

B PROMS

U3, U4, U14, U24

PRI DATA TEMPORARY STORAGE. 16 bits of PRI data from A-W/A-F/B, and 16

(4)

bits of PRI data from the VAR PRI switch S5, via contact denouncers U2,

U12, U22, are OR'ed at the input of the PRI data temporary storage U21,

U11, U1, U27. The information stored is determined by the enable

signals from the PRI select switch S7.

2-30