SLM-3650 Satellite Modem
Revision 3
Operation
MN/SLM3650.IOM
3–76
CUSTOMER
DATA
IBS or IDR
INTERFACE
ENCODER/
MODULATOR
TX = 70 MHz
TRANSMIT RF
EQUIPMENT
ANTENNA
AC POWER
POWER
MICRO-
COMPUTER
REMOTE SERIAL
INTERFACE
FAULT INDICATORS
SUPPLY
RECEIVE RF
EQUIPMENT
DEMODULATOR/
DECODER
SATELLITE MODEM
LOOPBACK CHANGES DEMOD
RECEIVE FREQUENCY TO
70 MHz WITHOUT LOSING
ORIGINAL PROGRAMMING
INFORMATION.
RF LBK = 70 MHz
RX = 73 MHz
DATA
Figure 3-23. RF Loopback
Note:
When RF loopback is turned ON, the demodulator receive frequency is programmed to be the same frequency as the
modulator transmit frequency. This test mode will verify the satellite link without changing the programmed frequency of the
demodulator. When RF loopback is turned OFF, the demodulator is programmed back to the previous frequency.
CUSTOMER
DATA
IBS, IDR or 308-2
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 3-24. IF Loopback
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 the previous frequency and is reconnected to the IF input.
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