TTC T-BERD 107A, Reference Manual

Page: 49 / 261

SECTION 3
3-10
INSTRUMENT
DESCRIPTION
PATTERN Switch
3
This switch selects the transmitted test pattern and
configures the receiver for the selected test pattern.
Press either the up arrow or down arrow to scroll
through the available selections. Release the switch
when the desired selection appears in the PATTERN
display. Changing the
PATTERN switch position
clears all test results and causes a test restart.
When the DATA BITS or VF RESULTS test results
are displayed for a user-selected DS0 channel, the
PATTERN switch is used to change the channel.
The following test patterns are available:
ALL ONES — ALL ONES is a fixed test pattern
of AMI pulses (marks) and is generally used to
stress span repeater current regulator circuits. It
can be used as an Alarm Indication Signal (AIS)
in unframed circuits, or a keep alive signal, idle
code, or red alarm in other circuits.
1:1 — 1:1 is a fixed test pattern of alternating
AMI ones (marks) and zeros (spaces). 1:1 is
generally used to perform a minimum level
stress test on clock recovery circuits.
1:7 — 1:7 is a fixed test pattern of F0100 0000.
The pattern is aligned with the framing (F) bits
as indicated. 1:7 is generally used to stress the
minimum ones density requirement for AMI-
encoded T1 circuits.
2 IN 8 — 2 IN 8 is a fixed test pattern of F0100
0010. The pattern is aligned with the framing (F)
bits as indicated. 2 IN 8 is generally used to stress
the minimum ones density for B8ZS-encoded
T1 circuits.