Q-Lite Satellite Modem Installation and Operating Handbook
5-13
5.7 Utilities Card Connectors
The connectors on the optional P3719 Utilities card are as follows:
•
Station Clock
This is a 75
Ω
BNC female connector that accepts a 1MHz to 10MHz signal, either
a square wave of >1V peak-to-peak or a sine wave at a power level of 0dBm or
greater. Alternatively, the station clock signal can be input as an RS422 signal on
the Async ESC connector.
The station clock acts as a clock for either the modem receive circuit (or, if the
input is at exactly 10MHz, for both the receive and transmit circuits). It is therefore
possible to maintain clock synchronization between several modems by feeding a
common master clock signal into all of them.
•
Alarms and AGC Connector
This is a 15-pin D-type male connector that provides access to four ‘form-C’ relay
contacts that indicate alarm conditions. An AGC output is provided that is suitable
for peaking antenna position.
The alarm relays have the following definitions:
Unit Fault
: A fault exists on the unit indicating an equipment failure.
Traffic Prompt
: A Tx traffic fault exists.
Rx Traffic Prompt
: An Rx traffic fault exists.
Deferred Alarm
: One of the following conditions exists:
•
The receive Eb/No is lower than the user-defined threshold.
•
Buffer slips are more frequent than the user-defined threshold.
•
A backward alarm is being received from either the satellite or terrestrial
ports.
•
1:N (1:1) Redundancy Connector
The modem has a built-in 1:1 redundancy controller that connects to the other
modem in the 1:1 pair via a 9-pin D-type male connector. A 1:1 redundancy system
requires two modems, a 1:1 control cable between the two redundancy connectors,
a ‘Y’ cable for splitting the traffic path and passive splitters and combiners for the IF
ports. An overview of 1:1 operation is provided in
Section 8.4
.
