VOICE DECODER (VD) CARD

T.O. 31W-2GSC24-2

TM 11-5805-688-14-1

NAVELEX 0967-LP-545-3011

of the high-speed serial data stream and converts the

5-138. OVERALL

DIAGNOSTIC

FUNCTIONAL

data into the original asynchronous data format (without

BLOCK DIAGRAM.

timing) that was applied to the far-end multiplexer.

5-139. GENERAL.

5-134. The write and read function for writing and

reading data bits into and out of the data elastic storage

5-140. The diagnostic circuits in the multiplexer set

monitor the equipment for error conditions. When an

The data out of the register are arranged in a series of

error is detected, a visual display on the front panel

3bit transition codes. These codes are applied to the

indicates the existence and source of the malfunction.

transition decoder, which produces one pulse transition

On the front panel, the malfunction source is identified as

for each 3-bit code applied to it. The result is a series of

either a faulty input signal to the multiplexer set or as a

reconstructed data pulses that are clocked through the

failed subassembly within the equipment. The diagnostic

data output buffer to the data output drivers. The pulses

circuits also generate electrical error signals (remote

applied to the data output drivers are conditioned and

alarms) representative of the front panel indications. The

processed into complementary demultiplexer channel

remote alarm signals are routed to one multipin

data output signals DOXX and DOXX-.

connector on the rear panel, where the signals can be

remoted to other equipment.

5-135. VOICE DECODER (VD) CARD.

5-141. Each plug-in card type in the multiplexer set

5-136. The VD card receives the high-speed serial data

contains diagnostic error detection circuits that

in the form of synchronous data (DTIX-) from the FS

continually generate one or more error or no-error status

card. The VD card function is basically the complement

signals to the display card. The display card, in turn,

of the VE card function in the multiplexer. Functionally,

generates signals that enable the indicators on the front

the VD card demultiplexes one channel of digitized voice

panel when an error condition is detected. An error

data out of the high-speed serial data stream, converts

status signal from the diagnostic circuit in the power

these data into analog signals, and filters the

supply is routed directly to a diagnostic circuit on the

reconstructed analog signals into the original voice

front panel. The remote alarm signals are generated by

waveforms applied to the far-end multiplexer input

the display card, the ERD card, and the front panel.

channel.

5-142. The functional diagnostic circuits on the display

5-137. The incoming digital data bits are applied

card contain priority encoding circuits that establish an

through a shift register to the digital-to-analog (D/A)

order of priority when more than one error condition is

conversion circuits. The analog signals from the D/A

simultaneously applied to the display card. It is possible

conversion circuits are applied through a bandpass filter

that some of the circuits being monitored in the

circuit to the output amplifier-drivers. The signals are

multiplexer set may produce a false error condition as a

amplified through the output amplifier-drivers to produce

result of faulty signal inputs from the true error source.

data

output

signals

DOXX

and

DOXX-

5-31