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5 TROUBLESHOOTING
Testing the RF Modulator
Although these test modes are mainly intended for factory testing, they can be
useful in isolating specific faults. Table 5-3 summarizes the modulator port test
m o d e s .
Note: The mode of the RF modulator can be changed on the Physical Interface
Configuration screen (Figure 4-15) in the Element Manager.
Table 5-3 — Modulator port testing modes
M o d e
D e s c r i p t i o n
CW test The RF modulator generates a single CW signal. The signal frequency is exactly the same as
the center frequency of the QPSK-modulated signal. The signal level is equal to the
composite level of the QPSK signal. This mode is useful for exact frequency measurements,
but should not be used for power leveling.
CON test The RF modulator operates the same as in the Operate mode, except that the digital FIR
filter coefficients are changed. In the Operate mode, the FIR filter frequency-response shape
is rectangular. In the CON Test mode, the FIR filter frequency-response shape is a raised
cosine with an alpha value equal to 0.5. This mode is useful for testing using a constellation
or vector analyzer.
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