Telecommunications Techniques Corporation interceptor 147, Reference Manual, Page: 54 / 280

3
Setup Categories
3-12
INTERCEPTOR 147 2 Mbit/s and Data Analyzer
OFF
When Thru Mode is set to OFF, an idle pattern (see
“TS Idle”) is transmitted on the unselected timeslots.
This selection is generally used for out-of-service
testing or Fractional testing when the unselected
timeslots are unused or not important.
3.3.3 Framing
Set the Framing item to the type of framing that you want
the Receiver to look for, and that you want the Transmitter
to use (as applicable). The framing can be set to the
unframed, multiframed, and framed modes listed below.
AUTO
When Framing is set to AUTO, the test instrument
attempts (at the start of each new test) to set Framing
to the framing format detected in the received signal.
If the test instrument cannot achieve frame
synchronization by setting framing to MFAS-CRC,
MFAS, FAS-CRC, or FAS, then the framing defaults
to UNFRAMED if Test Mode is set to 2048K, or
otherwise to FAS. (To determine which type of
framing was detected, check the LEDs in the STATUS
& ALARM section.)
When the automatic frame synchronization process is
complete, the framing remains fixed until a new test
is started. That is, if Frame Sync is achieved and then
lost, the test instrument does not re-initiate the
automatic synchronization process. Instead, the test
instrument indicates loss of Frame Sync and attempts
to reacquire Frame Sync using the framing that was
detected when automatic synchronization was initally
achieved. This procedure ensures that the test
instrument properly reports loss of sync, rather than
simply revert to the default.