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© MiMOMax 2013 Four Wire Audio
Interface Manual
5.2.4
HSSI Loop Back
It is possible to create a HSSI loop back cable for testing that allows a FWA unit to be
operated by itself where any enabled port will be directly looped back, this applies to both
audio and COM ports although limitations apply to the COM port while the loop back is in
place.
The Audio ports will behave as they would if the FWA unit was part of a normal point to point
system. If a channel is configured for E&M signalling then the E-Lead signal is similarly
required for audio to pass.
As the COM port will buffer the then delete data unless it can be determined that the air
interface is active an audio channel should also be active to ensure unrestricted data flow
when testing the COM port with a loop back cable.
Image Showing Loop Back Cable In Place.
HSSI Loop Back Connections
Signal
Pin (RJ45)
Pin (RJ45)
Signal
Tx Clock A
8
6
Rx Clock A
Tx Clock B
7
3
Rx Clock B
Tx Data A
2
5
Rx Data A
Tx Data B
1
4
Rx Data B
