Comtech EF Data CDM-710G, Installation And Operation Manual

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CDM-710G High-Speed Satellite Modem Revision 1
Front Panel Operation MN-CDM710G
6–44
6.3.3 SELECT: Test
Test:
Mode (
E)
Test options for the Tx carrier are selected in this menu. Select Mode using the ◄ ► arrow keys,
then press
ENTER
.
6.3.3.1 (SELECT:) Test
Æ
Mode
Test: Normal RF IF I/O
Tx-CW Tx-1,0 (
E)
The CDM-710G 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).
Select Norm, IF (Loop) , I/O (Loop) , RF (Loop) , Tx-CW or Tx-1.0 using the ◄ ► arrow keys,
then press
ENTER
.
Each test mode option is further explained as follows:
SELECTION DESCRIPTION
Norm
(Normal)
This clears any test modes or loopbacks and places the unit back into an
operational state.
IF
(IF Loop)
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.
I/O
(Input / Output Loop
) This test mode invokes two distinct loopbacks. The first
Loopback is an inward loop that 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.
RF
(RF Loop)
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.
Tx-CW
(Transmit CW)
This test mode forces the modulator to transmit a pure carrier
(unmodulated).
Tx-1,0
(Tx 1, 0, 1, 0 Pattern)
This is a test mode that 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.