MIL-I-81987(AS)
3.7.1.8
Output Signals - The indicator Monitor shall provide output
signals as follows.
3.7.1.8.1
Stored Message Data - Control Messages composed of synchronization
pattern, aircraft address, data fields, and parity bits as specified in WR-28A shall be
provided as an output for use by the SM511A/ASW and AN/ASW-27B. This signal is the
buffered output of the Stored Message Generator and the occurrence is determined by the
particular operating mode as detailed in Paragraph 3.7.1.5.4. A binary ONE shall be
V DC and a binary ZERO by -5.0
V DC .
represented by +5.0
3.7.1.8.2
Record Data - This signal shall be the Receiver Data input signal
conditioned and buffered for use by an external recorder, A binary ONE shall be represented
V DC and a binary ZERO by -5.0
V DC.
by +5.0
3.7.1.9
Message Synchronization - The synchronization of messages shall
consist of (1) recognition of the unique synchronization pattern in a Control Message as
specified in WR-28A, (2) correlation of the Control Message aircraft address code with the
code selected on the A/C thumbwheels, (3) detection of the correct Control Message
direction bit defined in WR-28A, (4) recognition of the unique synchronization pattern in the
Reply Message 30 to 40.4 miIliseconds after the end of the properly addressed Control
Message, and (5) detection of the correct Reply Message direction bit defined in WR-28A. The
synchronization and subsequent processing of a Reply Message shall be completeIy dependent
upon prior receipt of an appropriate Control Message.
3.7.1.10
Message Processing - The processing of messages in the test set
shalI consist of (1) storage and display of 42 data bits for either Control or Reply Messages,
(2) detection, storage and display of Control Message parity, (3) storage and display of
Control Message cancel reply bit, and (4) appropriate conversion, storage and display of
RO, R1, R3A, R3B, and R3C Reply Messages.
3.7.1.10.1
C-MSG Processing - In this mode of operation, the 42 data bits of
Control Messages with aircraft address and label codes corresponding to selected codes on A/C
address thumbwheels and label select switches respectively and with correct direction bit will
be transferred to a holding register and displayed on the 42 bit binary readout. The test set
shall check the three parity segments of Control Messages and light the CMD error indicator
if one or more of the parities is incorrect. The 42 data bits shall be displayed irrespective of
parity errors.
3.7.1.10.2
R-MSG Processing - in this mode of operation, the test set shall first
synchronize on a properly addressed Control Message. The cancel reply bit of the Control
Message shall be stored and an appropriate indication given on the Cancel Reply indicator.
The test set shall time the period, 30-40.4 milliseconds, in which a Reply Message should
occur, irrespective of the Control Message cancel reply bit. If no Reply Message occurs
during this window or if the Reply Message direction bit is incorrect, the No Reply indicator
shall be lit. The test shall not process a Reply Message with an incorrect direction bit.
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