Comtech EF Data CDM-IP 300L - Manual (Page 318)

CDM-IP 300L IP-Centric Satellite Modem Rev. 1
CD/CDMIP300L.IOM
292
10.1.2 D
EMODULATOR
C
HECKOUT
Use the following procedure to test the demodulator.
1 Set up the equipment.
2 Set up the modem with an external IF loop and level. Use a properly operating modulator,
and ensure that power levels, data rates, code rates, etc., are compatible.
3 Set up the modem to check the constellation patterns with an oscilloscope that is set in
the X-Y mode. Typical constellation patterns with noise and without noise are shown in
Figure 21. These test points are available on the auxiliary connector (J9, pins 6 and 8). It
is not necessary to open the modem to look at these test points.