SDM-300L3 Satellite Modem
Revision 0
Specifications
MN/SDM300L3.IOM
14–40
14.17 System
Specifications
14.17.1 Loopback
Modes
The operator can select one of the following interface loopback test modes.
•
Baseband: Near end and far end.
•
Interface: Near end and far end (Reed-Solomon or Overhead only).
14.17.2 Test
Modes
The following receive IF test modes are available.
IF loopback
Disconnects the IF input from the receive input connector and couples it to a sample of
the transmit IF output. The IF output is not affected.
Note: The TX and RX data rates must be the same for the modem to lock.
RF loopback
Sets the demodulator frequency to the same value as the modulator. For the modem to
lock, an external IF loop must be provided.
Note: The TX and RX data rates must be the same for the modem to lock.
BIST (Built in Self
Test)
The modem has the ability to generate 2^11-1 (2047) PN data and pass the data
through the Interface, Modulator and Demodulator sections of the modem. The modem
can generate noise in the IF path to simulate a satellite environment. The true BER can
then be measured by the modems built in BER monitor. The operator can invoke this
feature on power up or and the result checked against specification and a fault is
flagged if the unit fails. The feature can be turned off at the front panel if so desired to
minimize initialization time. The RF output is off during this self-test.
2047 Pattern
Generator (must have
overhead card
installed and
activated)
Inserts an Industry Standard 2047 pattern in lieu of the transmit data stream.
2047 Pattern Monitor
(must have overhead
card installed and
activated)
Monitors the RX data for 2047 pattern. If 2047 pattern is present, this test mode
provides an indication of Bit Error Rate (BER). The RX data is not interrupted.
