Comtech EF Data SNM-1002 - Manual (Page 109)

5–1
Chapter 5.
MAINTENANCE
This chapter provides the following information:
• System checkout
• Fault isolation
• Module replacement and identification
5.1 System Checkout
CAUTION
This equipment contains parts and assemblies sensitive to damage by ESD.
Use ESD precautionary procedures when touching, removing, or inserting
PCBs.
The modem comes equipped with an internal self-test feature. This feature is designed to
provide the operator with maximum confidence that the modem is fully operational
without installing external equipment.
A 2047 pattern is generated by the modem and routed through all sections. This is
accomplished by placing the modem in IF and baseband loopbacks. Pseudo Gaussian
noise is introduced to the modulated IF section allowing the modem to check its indicated
E
b
/N
0
against the known E
b
/N
0
of the demodulated input. Observe the following:
• If this measurement falls outside of a specified window, the modem declares a
failed test.
• Faults, if any, are stored in the Stored Fault menu.