Carrier Modes - Comtech EF Data SLM-7650 Installation And Operation Manual

SLM-7650 Satellite Modem
Maintenance
5.3.4.3

Carrier Modes

There are three carrier test modes available in the Configuration - Modulator menu. The
normal setting is Carrier mode OFF. Exiting any of the carrier test modes will turn the IF
Output OFF and the operator will be required to manually turn it back ON.
5.3.4.3.1 Center Carrier Wave
Center Carrier Wave (Figure 5-8) will turn off the modulation on the IF carrier. A center
frequency will be transmitted at the output of the modulator. This is useful for checking
the frequency accuracy and phase noise of the modulator.
5.3.4.3.2 Offset Carrier Wave
Offset Carrier Wave (Figure 5-7) will present two sine waves, 90 degrees apart to the IF
carrier. This will cause the carrier waveform to have a peak at the high end of the IF
band-pass and a lower peak to the left of center. The center carrier will be present but at a
low level. This test mode is useful for checking the quadrature balance and carrier null.
The center carrier should be at or below 35 dBc from the carrier peak.
5.3.4.3.3 Dual Carrier Wave
Dual Carrier Wave (Figure 5-6) will generate a dual side-band suppressed carrier signal.
This is useful for checking carrier null and quadrature balance. The two peaks should be
at the same output level. The modulator is presented with alternating ones and zeroes.
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MN/SLM7650.IOM