Initializing the Maintenance Terminal Screens
150-402-111-02
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December 8, 1998
HRU-402 List 1A
Loopback Operation
Loopbacks permit you to perform isolated diagnostic tests at specific points
of the circuit. The transmitted signal is returned to the sending device after
passing through a data communications link or network. This allows you to
compare the returned signal with the transmitted signal and to determine if
there is a problem with the circuit. Ideally, personnel performing loopback
testing are in direct communication with each other in order to correlate
messages displayed at both the HRU and HLU during the test.
Figure 18.
HiGain System Loopbacks