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Backward alarms faults, 6 backward alarms faults – Comtech EF Data SDM-300L3 User Manual

Page 257

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SDM-300L3 Satellite Modem

Revision 1

Fault Isolation

MN/SDM300L3.IOM

9–9

9.1.3.6 Backward

Alarms

Faults

Fault/Alarm

Possible Problem and Action

BW ALARM RX4

Receive backward alarm #4. The distant end of the link is sending
backward alarm #4. This indicates trouble at the distant end, which may
be a result of improper transmission at the near end of the link. The
modem will signal this event by setting the deferred maintenance alarm
(open collector). This alarm is a monitor function. The modem reports and
records the event, but takes no other action. Refer to Chapter 2 for the
backward alarm theory of operation. If the user does not wish to monitor
the backward alarm faults, the backward alarm inputs must be grounded at
the breakout panel. Refer to Chapter 2 for breakout panel pinouts.

BW ALARM RX3

Receive backward alarm #3. Refer to BW Alarm RX4 for details.

BW ALARM RX2

Receive backward alarm #2. Refer to BW Alarm RX4 for details.

BW ALARM RX1

Receive backward alarm #1. Refer to BW Alarm RX4 for details.

BW ALARM TX4

Transmit backward alarm #4. The modem is being instructed to send
backward alarm #4 to the distant end of the link. This alarm is controlled
by wiring the backward alarm inputs of the modem to the demod fault
relay and/or other fault outputs in the receive system (see IESS-308 for
clarification). The simplest implementation for single destination service is
to wire the demod fault relay between ground and the four backward
alarm inputs (see Chapter 3 for clarification). This sends all four backward
alarms in the event of any major (prompt) receive fault. This particular
alarm is transmitted, reported, and recorded, but the modem takes no other
action. In most cases, this will be sent due to some receive problem with
the modem, so a real fault will probably be occurring if backward alarms
are being sent. The transmit backward alarms are a symptom of trouble,
not a cause.

BW ALARM TX3

Transmit backward alarm #3. Refer to BW Alarm TX4 for details.

BW ALARM TX2

Transmit backward alarm #2. Refer to BW Alarm TX4 for details.

BW ALARM TX1

Transmit backward alarm #1. Refer to BW Alarm TX4 for details.