SEQUENCER (SEQ) CARD - TM-11-5805-688-14-10222

T.O. 31W2-2GSC24-2

TM 11-5805-688-14-1

NAVELEX 0967-LP-545-3011

The result is a decreased drive voltage to integrator U2-

diagnostic indication to be generated from the VD card.

10, thus decreasing the slope of the analog signal being

reconstructed.

5-460.SEQUENCER (SEQ) CARD.

5-457. Bandpass filter circuit U2-12, U1-10 forms a

5-461. The seq card used in the demultiplexer is the

bandpass filter that re- moves the high-frequency

same card type as that used in the multiplexer. The seq

quantizing noise present at the output of U2-10. The 3-

card requires no functional modifications for use in the

dB bandpass of the bandpass filter is from 140 to 3500

demultiplexer. The seq card logic diagram and the block

Hz. The response of this bandpass filter is that of a low-

diagram in figure FO-3 identify the in- put and output

pass elliptic filter followed by a Butterworth bandpass

signals that are applicable to the multiplexer function,

filter. The set- ting of amplitude control R36 is factory

and those that are applicable to the demultiplexer

preset to produce a +7-dBm output for a -16-dBm input.

function. The signals pre- fixed by a D are applicable to

The reconstructed analog voice signals are applied

the de- multiplexer, and those prefixed by an M are

Q4,

through out- put amplifier U1 to push-pull driver circuit

applicable to the multiplexer. Those signals not prefixed

Q5. The voice output signals are developed as channel

by a D or an M are used in both the multiplexer and the

data out- put signals DOXX and DOXX- from the 600-

demultiplexer.

There is one exception; maximum

ohm output of audio transformer T1.

channel number signals CHMAXO through CHMAX3 are

used by the seq card only in the multiplexer and not in

5-458. Diagnostic Circuits.

the demultiplexer.

5-459. Transistors Q7 and Q8 are normally cut off and

5-462. Functional operation of the logic circuits on the

Q9 is conducting. When an error condition is detected,

seq card in the demultiplexer is the same as that de-

either Q7 or Q8 is forced into conduction and, in turn,

scribed for the seq card in the multiplexer, with one

Q9 is biased into cutoff. When Q9 is cut off, an enable

difference. When the equipment is initially turned on or

signal is applied to one input of AND gate U9-12. When

frame synchronization has been lost,

the frame

the three inputs to U9 are high, the low output from U9

synchronization circuits on the FS card generate and

is applied through OR gate U9-6 and inverter U9-8 to

supply frame sync signal DSYNC- to the seq card. Signal

generate a card error signal that is applied on the

DSYNC- is produced on the FS card as part of the

positive stuff request (DPSTXX-) line to the OEG card.

resynchronization function that involves the GC/DM and

When the incoming data are missing, loss-of-data

seq cards. Signal DSYNC- is applied through inverters

multivibrator U8-6 produces a low inhibit output to AND

U4-2, U4-12, OR gate U15-11, and inverter U4-8 to

gate U9-12. This circuit prevents an erroneous card

preset port scan counter U2, U3 to a count of five. The

error from being generated by loss of data. Multivibrator

count four input to U2 is held high at this time by signal

U8-6 is a retriggerable one-shot multi- vibrator that is

DSYNC- applied through inverter U4-2. At the same

held in conduction by the incoming data pulses. Once

time, flip-flops U21-5 and U21-9 in the end-of-scan

the pulse inputs are removed, the multi- vibrator duty

signal generator circuits are cleared. Write port scan

cycle expires and generates the inhibit (low) output.

counter U9, U22 is preset to a count of three by the low

Delay start multivibrator U8-9 is triggered on for 2.7

output from inverter U4-10 applied through OR gate U15-

seconds by the low Q output from Q8-6 when the

8 and inverter U24-12 to the preset input of U9, U22.

equipment is first turned on to prevent an erroneous

5-121