Figure 3-27. If Loopback; Figure 3-28. Baseband Loopback - Comtech EF Data SDM-100A Installation And Operation Manual

Operation
CUSTOMER
DATA
REMOTE
SERIAL
INTERFACE
FAULT
INDICATORS
SDM-100A
SATELLITE
DATA MODEM
Note: When IF loopback is turned on, the demodulator is looped back to the modulator inside the modem, and the
demodulator is programmed to the same frequency as the modulator. This test mode will verify the operation of the
modem. When IF loopback is turned off, the demodulator is programmed back to its previous frequency, and is
reconnected to the IF input.
CUSTOMER
DATA
REMOTE
SERIAL
INTERFACE
FAULT
INDICATORS
SDM-100A
SATELLITE
DATA MODEM
Note: When baseband loopback is turned on, the data signal is looped back on the customer side of the interface.
This test mode will verify customer equipment, as well as cabling between the modem and the customer equipment.
3–78
ENCODER/
INTERFACE
MODULATOR
MICRO-
COMPUTER
DEMODULATOR/
DECODER

Figure 3-27. IF Loopback

ENCODER/
MODULATOR
INTERFACE
MICRO-
COMPUTER
DEMODULATOR/
DECODER

Figure 3-28. Baseband Loopback

SDM-100A Satellite Modem
TRANSMIT RF
EQUIPMENT
POWER
AC POWER
SUPPLY
RECEIVE RF
EQUIPMENT
TRANSMIT RF
EQUIPMENT
POW ER
AC POW ER
SUPPLY
RECEIVE RF
EQUIPMENT
ANTENNA
ANTENNA
Rev. 0