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Figure 7-6 displays the T1 measurement data in Histogram mode.
Out-Of-Service Testing
Out-of-service measurements are performed when the T1 circuit is not in service or inac-
tive. Typically these tests are done during initial installation, during circuit acceptance by
the wireless service provider or when the results of the in-service measurements indicate er-
rors. These measurements provide detailed information on the T1 circuit.
There are two methods of performing out-of-service testing: end-to-end and loopback test-
ing. End-to-end testing requires a technician and a unit at each end of the circuit. Loopback
testing requires a loopback at one end of the circuit and a unit and technician at the other
end to measure the round trip of the T1 performance.
The ANSI T1 standard defines in-band and out-of-band loop codes. In-band codes are
transmitted in place of payload data and are repeated continuously for a period of five sec-
onds. They can be used either with D4 SF or ESF. Out-of-band loop codes can only be used
with the ESF framing format as an out of band communication link does not exist for D4
SF.
The following measurements can be used to check T1 performance during out of service
testing:
q
Vpp
q
Carrier
q
Insert Errors/Alarms
q
Frame Sync
q
Pattern Sync
q
Remote/Self Loop Codes
Required Equipment
q
MT8212B Cell Master with Option 50
q
Bantam Cables, Anritsu Part Number 806-16 (2)
Chapter 9 T1 Measurements
9-7
Figure 9-6. T1 BERT Measurement Display with Histogram