CDM-570/570L Satellite Modem with Optional IP Module Revision 4
Physical Description MN/CDM570L.IOM
4.3.4 External Reference Connector
This is BNC female connector. The signal supplied here by the user is used for phase-
locking the internal 10MHz reference oscillator, and can be 1, 2, 5, 10 or 20 MHz. The
impedance is matched for 50/75Ω, and requires a level in the range –6 to +10 dBm.
4.3.5 Form C Traffic Alarm Connector
The Alarms connector is a 15-pin 'D' type male (DB15-M). This provides the user with
access to the Form-C relay contacts which indicate the fault status of the unit. These are
typically connected to an external fault monitoring system, often found in satellite earth
stations. In addition, the receive I and Q demodulator samples are provided on this
connector. Connecting these signals to an oscilloscope in X,Y mode will provide the
receive signal constellation diagram, which is a useful diagnostic aid. A pin is also
provided which can mute the transmit carrier. This requires that the pin be shorted to
ground, or a TTL ‘low’, or an RS232 ‘high’ signal be applied.
As an aid to antenna pointing, or for driving step-track equipment, an analog AGC signal
is provided on Pin 2 of this connector.
4.3.6 Balanced G.703 Connector Tx/Rx Connector
A 15-pin 'D' type female (DB15-F) for balanced operation at the G.703 data rates of T1
(1.544 Mbps) or E1 (2.048 Mbps).
4.3.7 Unbalanced G.703 Tx/Rx
Two female BNC 75Ω connectors for unbalanced operation at the G.703 data rates of E1
(2.048 Mbps).
4.3.8 Remote Control Connector
The Remote Control connector is a 9-pin ‘D’ type male (DB-9-M). Access is provided to
remote control ports of the modem, both EIA-232 and EIA-485.
4.3.9 1:1 Control Connector
This connector is used to connect the modem to a CRS-170 switch in 1:1 redundancy
configurations.
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