Mocomtech CDM-QX - Manual (Page 49)

CDM-Qx/QxL Multi-Channel Satellite Modem with DoubleTalk™ Carrier-in-Carrier® Revision 7
Installation MN/CDMQX.IOM
2–5
2.4 Select Internal IF Loop
Correct operation of the unit may be verified rapidly, without the need for externally connected
equipment, provided that there is at least one modulator and one demodulator installed:
1. From the top-level menu, select CONFIG Æ GROUP Æ MODEM .
IMPORTANT
This will require a modulator, with TX Output
ON or ENABLED,
installed in the rear panel of the chassis into the slot above its
paired demodulator.
2. From the top-level menu, select TEST Æ IF LOOP (refer to Chapter 5. FRONT
PANEL OPERATION for details).
The demod should synchronize, and the green Rx TRAFFIC LED should illuminate. If the unit
does not pass this test, call Comtech EF Data Customer Support for assistance.
2.5 Connect External Cables
Having verified correct operation in IF loop, enter the desired configuration and proceed to
connect all external cables to the connectors outlined in the next chapter (Chapter 3. REAR
PANEL CONNECTOR PINOUTS). Should difficulties occur, call Comtech EF Data Customer
Support for assistance.
Observe the following:
• If modulators and demodulators are to be used without grouping them as a modem, a data
interface cable is required to plug into each unit. If a modulator and demodulator are
paired as a modem, the modulator must be located above the demodulator and a single
data interface cable is used simply by connecting it to the demodulator.
• If a modulator, demodulator, or pair (modem) is defined as a backup unit, a data interface
cable is not required to the unit or units.
CAUTION
Each modulator has an output power level in the range -5 to -25 dBm (-5 to -45
dBm for L-Band). Even though there is a single IF output connector and a single
IF input connector, all four slots are hooked up by way of internal power splitters
and summers. If two modulators are turned on, the total power out will be 3 dB
higher (assuming both modulators are set to the same power level). If four
modulators are turned on, the total power out will be 6 dB higher (assuming all
modulators are set to the same power level).