Comtech EF Data CDM-570 - Manual (Page 126)

CDM-570/570L Satellite Modem with Optional IP Module Revision 12
Front Panel Operation MN/CDM570L.IOM
5–40
Selection Description
TX-1,0
(Transmit an alternating 1,0,1,0 pattern) Used to check the carrier suppression of the Modulator.
This test mode forces the modulator to transmit a carrier modulated with an alternating 1,0,1,0
pattern, at the currently selected symbol rate. This causes two discrete spectral lines to appear,
spaced at +/- half the symbol rate, about the carrier frequency.
If OQPSK is selected as the modulation type, the test produces a spectral pattern suitable for the
measurement of SSB rejection – useful in determining the phase and amplitude accuracy of the
modulator.
Figure 5-4. Loopback Modes