Technical data

508 Chapter 18
T1 Analyzer
Making T1 Measurements
T1 Analyzer
during loopback. Loopback tests are normally limited to the CSU since NIU loop
codes are normally suppressed at the central office. When the test set is in a
loopback state, AIS is present at the Secondary Tx jack. When not in loopback state,
the Primary Rx signal is routed to the Secondary Tx jack and the Secondary Rx
signal is routed to the Primary Tx jack.
NOTE Avoid having a hard loop in the Secondary channel as it will cause a constant loop
condition to exist.
You may want to emulate the functionality of a CSU/NIU if trouble is suspected in
that equipment. The wireless technician will often be interested in only the CSU
mode. The functionality of a CSU is emulated in this mode and the test set will
respond to loop codes received at the Primary Rx input.
The test set has the capability to emulate the functionality of a CSU/NIU.
The test set will respond only to the type of loop code selected on the setup screen.
Be aware that when the test set is not in loopback mode, the source of data on the
Primary Tx jack is the Secondary Rx jack, and the source of data on the Secondary
Tx jack is the Primary Rx jack. If B8ZS is selected on the test set, then the signal (or
no signal - which is decoded as all zeros) will be translated to B8ZS format.
Figure 18-5 Sample Emulate CSU/NIU Test Setup
The following table provides the data source for primary Tx and secondary Tx