Comtech EF Data CIM-300L - Manual (Page 141)

CiM-300L IP Enabled Satellite Modem Rev. 1
System Checkout/Fault Isolation CD/CIM300L.IOM
115
Figure 7-1. Typical Output Spectrum
7.1.2 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 7-4. 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.