Figure 5-10. Manual Tuning Timing Diagram

TM 11-5865-215-13

conversion circuits on CCA A3. The A-quad-B conversion circuits then

convert the PHASE A and PHASE B signals to binary data (see figure

FO-10).

D flip-flops U5A and U5B, together with JK flip-flop U6B, comprise

the A-quad-B circuit and convert the PHASE A and PHASE B pulse inputs

from the front panel optical encoder (MANUAL TUNING control) into

binary data (see figure 5-10). These data change the frequency field

of the receiver control receiver command (51 bit) word. When the

MANUAL TUNING control is rotated clockwise, the PHASE A pulses lead

the PHASE B pulses. This causes flip-flop U5A to reset, providing a

0 (increase frequency) bit to the DO port of output register U11B.

The PHASE B input also clocks flip-flops U5B and U6B to produce pulse

inputs to the D1 port of output register U11B. The pulse rate of this

input is proportional to the rate at which the MANUAL TUNING control

is rotated. Counterclockwise rotation of the MANUAL TUNING control

causes U5A to set. This produces a high 1 (decrease frequency) bit

input to register U11B. Again, the pulse output rate is determined by

the speed at which the MANUAL TUNING control is rotated. An active

(low) output port 7 OB73 bit transfers the MANUAL TUNING data in reg-

ister U11B to the respective IB20 and IB21 lines of microprocessor

input port 2.

Manual Tuning Timing Diagram

5-27