P300H P300 Series Modem Installation and Operating Handbook Page 182
ALARMS & AGC CONNECTOR
Connector type : 15 pin `D' male
ALARMS CONNECTOR
2, 12 Fault Relay - Common
4 Prom pt Unit fault - N/O
11 Prompt Unit fault - N/C
3 Prompt Traffic fault (prompt) - N/O (c/o pair a)
10 Prompt Traffic fault (prompt) - N/C (c/o pair a)
5 Prompt Traffic fault (prompt) - N/O (c/o pair b)
13 Prompt Traffic fault (prompt) - N/C (c/o pair b)
1 Deferred alarm - N/O
9 Deferred alarm - N/C
6 Uncomm itted analog output from processor (If Monitor/AGC option fitted).
Selectable Rx signal level, Eb/No, IF offset freq et c, s ee Appendix E
7 Transmit inhibit
8 Buffered direct AGC voltage. This may be used as an antenna pointing signal
when the demod is unlocked. It responds to composite power in approximately
a 2MHz bandwidth around the nominal Rx carrier frequency .
14 Not connected
15 Ground
To externally inhibit the Transmit carrier, either apply a TTL/CMOS 'low' signal to pin 7, or short pin 7 to
ground (for example with an external relay closure).
All relay contacts rated 30V DC 2A, or 125VAC 0.4A. The functions are as defined below:
Prompt Unit: A unit fault exis t s, i.e. an equipment failure.
Prompt Traffic: A Tx or Rx traffic fault exists.
Deferred alarm: One of the following conditions exists:
The receive BER is greater than the user defi ned threshold.
The receive Eb/No is lower than the user defined threshold.
Buffer slips are more frequent than the user set threshold.
A Backward al arm is being received from either the satellite or
terrestrial ports.
Note: N/O means 'normally open' in the non-fail state of the modem (relays energised), when power is
removed the relays fall back to the non-normal (ie non-energised) alarm state.
Note: The function of these relays can be changed. See “Relay Mode” in Appendix E: Customer Specific
Features on page 201 for a description.