Test; Test: Mode - Comtech EF Data CDM-710 Installation And Operation Manual

CDM-710 Broadcast Satellite Modem
Front Panel Operation

5.3.3 Test

Test:
Mode TestPatterns
Test selections for the Tx carrier and Patterns are selected in this menu.

Test: Mode

The CDM-710 supports many useful test modes. Not all modes are available in all
configurations. They depend upon the modem configuration (Duplex, Rx-Only, Tx-Only) and
the data interface(s).
Test: Normal
Tx-CW Tx-1,0 ( E)
Tx-CW produces a CW carrier at the output of the modulator. Tx=1,0 generates a Single
Sideband Carrier to evaluate carrier leakage and sideband suppression.
Select Norm, IF Loop, I/O Loop, RF Loop, Tx-CW or Tx-1.0 using
press ENTER .
Norm
(Normal)
IF
(IF Loop)
I/O
(Input / Output
Loop)
RF
(RF Loop)
Tx-CW
(Transmit CW)
Tx-1,0
(Tx 1, 0, 1, 0
Pattern)
E)
RF IF I/O
This clears any test modes or loopbacks and places the unit back into an
operational state.
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 Rx configuration parameters are
temporarily changed to match those of the Tx-side. When Norm is again selected,
all of the previous values are restored.
This test mode invokes two distinct loopbacks. The first Loopback is an 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 Tx data interface is routed directly back out of the Rx data interface.
This RF loop is almost identical to the IF loop mode. All of the Rx configuration
parameters (except Rx Spectrum Invert) are temporarily changed to match those
of the Tx-side, however, no internal connection is made. This is useful for
performing a satellite Loopback. When Norm is again selected, all of the previous
values are restored.
This test mode forces the modulator to transmit a pure carrier (unmodulated).
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
single sideband 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. Also, it verifies quadrature and amplitude balance.
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Revision 9
MN/CDM710.IOM
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