ComStream CM601, Installation And Operation Manual

Page: 95 / 228

Configuration Examples 7-9
12. Select a modem transmit data rate of 1,640,000 bps, enter PTD 1640000 .
This assumes an IDR Framing Unit operating with a terrestrial data rate of
1,544,000 bps. The transmit data rate was calculated as 1 96000.
Check the transmit data rate by issuing a transmit symbol rate query command
TR ?
which should return a value of
1640000
sps.
13. Select a receive data rate of 1,640,000 bps, enter
PRD 1640000
.
This assumes an IDR Framing Unit operating with a terrestrial data rate of
1,544,000 bps. The receive data rate was calculated as 1 96000.
Check the receive data rate by issuing the receive symbol rate query command
RR ?
which should return a value of
1640000
sps.
Perform an IF Loopback
To perform an IF loopback, connect an IF cable between the Tx IF and Rx IF
connectors. The modem should acquire almost immediately. If it does not acquire,
perform the following steps:
1. Issue an EM 1 command to enable the modulator. When a modem is
factory-shipped, AE is set to one; therefore, EM should be set to one. If AE is
zero, ensure that the zero parameter is correct and determine the correct
setting for EM. For additional AE command information, refer to the chapter
on command descriptions.
2. Ensure that acquisition (AQ) is enabled. If it is not, reset the demodulator's
acquisition process, enter AQ 1 .
3. Test the equipment using the built-in BERT feature, if available:
a. Place the modem in internal time, enter
MB 2
.
b. Issue a
BEN 1
command.
Enabling the BERT will take the external Framing Unit out of the loop.