Premier Mounts CDM-600 Modem Test Mode = Normal NORM,TX-CW,TX-1/0,IF↓,RF↓,DIG↓,I/O↓

CDM-600 Satellite Modem	Revision 7
Front Panel Operation	MN/CDM600.IOM

6.3.2TEST

MODEM TEST MODE = NORMAL

(NORM,TX-CW,TX-1/0,IF↓,RF↓,DIG↓,I/O↓)

Select TEST Mode or Normal Operation from the parameters shown in the parentheses using the [↑] [↓] arrow keys, then press ENTER.

This sub-menu permits the user to select the following test modes:

NORM	(Normal) This clears any test modes or loopbacks, and places the unit back
TX-CW	into an operational state.
	(Transmit CW) This is a test mode, which forces the modulator to transmit a
TX-1,0	pure carrier (unmodulated).
	(Transmit an alternating 1,0,1,0 pattern) This is a test mode, which 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. This
	mode is used to check the carrier suppression of the Modulator.
IF LOOP	(IF Loopback) This test mode invokes an internal IF loop. This is a particularly
	useful feature, as it permits the user to perform a quick diagnostic test without
	having to disturb external cabling. Furthermore, all of the receive configuration
	parameters are temporarily changed to match those of the transmit side.
	When NORMAL is again selected, all of the previous values are restored.
DIG LOOP	(Digital Loopback) This test mode invokes a digital loopback, which loops data
	at the output of the Reed-Solomon encoder on the transmit side, back into the
	Reed-Solomon decoder on the receive side. This tests all of the interface,
	transmit baseband circuits, FEC encoder, FEC decoder, and buffer.
I/O LOOP	(Inward/Outward loopback) This test mode invokes two distinct loopbacks. The
	first of these is the inward loop, which takes data being received from the
	satellite direction, and passes it directly to the modulator. Simultaneously, the
	outward loop is invoked, whereby data being fed to the transmit data interface
	is routed directly back out of the receive data interface.
RF LOOP	(RF Loopback) This test mode is almost identical to the IF loop mode. All of
	the receive configuration parameters (except Rx Spectrum Invert) are
	temporarily changed to match those of the transmit side, however, no internal
	connection is made. This is useful for performing a satellite loopback. When
	NORMAL is again selected, all of the previous values are restored.

The IF, Digital, and I/O Loopback modes are illustrated in Figure 6-1.

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