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Demodulator checkout, 2 demodulator checkout, Figure 7-1. typical output spectrum – Comtech EF Data CIM-300L User Manual

Page 141

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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.

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