Backward Alarms - Comtech EF Data SDM-9000 Installation And Operation Manual

Maintenance

6.2.2.2.6 Backward Alarms

BW ALARM RX4
BW ALARM RX3
BW ALARM RX2
BW ALARM RX1
BW ALARM TX4
BW ALARM TX3
BW ALARM TX2
BW ALARM TX1
6–26
Fault/Alarm
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
is essentially a monitor function so 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 the B141-1 Breakout Panel Installation
and Operation Manual for breakout panel pinouts.
Receive backward alarm #3.
Refer to BW alarm RX 4 for details.
Receive backward alarm #2.
Refer to BW alarm RX 4 for details.
Receive backward alarm #1.
Refer to BW alarm RX 4 for details.
Transmit backward alarm #4.
The modem is being instructed to send backward alarm #4 to the
distant end of the link. This 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 2 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.
Transmit backward alarm #3.
Refer to BW alarm TX 4 for details.
Transmit backward alarm #2.
Refer to BW alarm TX 4 for details.
Transmit backward alarm #1.
Refer to BW alarm TX 4 for details.
SDM-9000 Satellite Modem
Possible Problem and Action
Rev. 4