Comtech EF Data SNM-1002 - Manual (Page 58)

SNM-1002 LinkSync
 Modem
Revision 2
Operation MN/SNM1002.OM
3–18
3.4.1.3.6 INTERFACE:B-BAND LOOP BACK
B-BAND LOOP BACK
OFF
Programs the modem for baseband loopback operation, On or Off.
When baseband loopback is turned on, the data and timing signals are switched from the
demodulator to the modulator on the modem side of the interface. The DTE baseband
signals are also looped back from the transmitter data and clock to receiver data and clock
on the customer side of the interface. This is a bi-directional loopback of the baseband data.
Refer to figure 3-4 for a block diagram of baseband loopback operation.
Upon entry, the status is displayed. Press [
↑] or [↓] to make the selection. Press [ENTER] to
execute the change.
CUSTOMER
DATA
IBS OR IDR
INTERFACE
ENCODER/
MODULATOR
TRANSMIT RF
EQUIPMENT
ANTENNA
AC POWER POWER SUPPLY
MICRO-
COMPUTER
REMOTE SERIAL
INTERFACE
FAULT INDICATORS
RECEIVE RF
EQUIPMENT
DEMODULATOR/
DECODER
SATELLITE MODEM
Figure 3-4. Baseband Loopback
Note: When baseband loopback is turned on, data is looped back on the customer side of the
interface. This is a bi-directional loopback of the baseband data. This test mode will verify the
customer equipment and cabling between the modem and the customer equipment. The baseband
loopback is not bi-directional in D&I.