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 loopcodes. In-band codes are trans-
mitted in place of payload data and are repeated continuously for a period of five seconds.
They can be used either with D4 SF or ESF. Out-of-band loopcodes 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
S331D Site Master with Option 50
q
Bantam Cables, Anritsu Part Number 806-16 (2)
7-6
Chapter 7 T1 Measurements
Figure 7-6.
T1 BERT Measurement Display with Histogram