Product specifications

CDM-710 Broadcast Satellite Modem Revision 10

Front Panel Operation MN/CDM710.IOM

(SELECT:) Test: Æ Mode

Test: Normal RF IF I/O

Tx-CW Tx-1,0 ( E)

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).

Select Norm, IF Loop, I/O Loop, RF Loop, Tx-CW or Tx-1.0 using the ◄ ► arrow keys, then

press

ENTER.

Selection Description

Norm

(Normal) This clears any test modes or loopbacks and places the unit back

into an operational state.

(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, 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.

(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, 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.

(SELECT:) Test: ÆTest Patterns

Test Pattern Subst:

Off 2047 2^23-1

The availability of test patterns depends on the type of interface.

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