11
Operation
Data detection is a two part process. The first part
requires listening to the line for audible data traffic in
Monitor mode as described above. If the line is quiet,
then the second part is to use the test set’s data detect
capability to determine if there is data above the
human audio range on the line. This can be done in
one of two ways.
•
You can test for high-speed data with the test set
still in Monitor mode by pressing the TEST key. If
there is high-speed data on the pair, the test set
generates an alarm for about 5 seconds. If there is
no data on the line, the test set generates a brief
confirmation tone. If the warning alarm is not
sounded, then switch the test set to Talk mode,
and it will go off-hook.
•
You can test for data by switching the Talk/
Monitor switch to T. The test set automatically
performs a brief test for high-speed data. If there
is data on the line, the test set locks out, (remains
on-hook) and generates a data warning alarm. If
there is no data on the line, the test set goes off-
hook.
When going from pair to pair searching for tracer tone
or dial tone it is best to connect the test set to Tip and
Ring of the pairs. Avoid the practice, either in Talk or
Monitor mode, of clipping one lead of the test set to
ground, and using the other lead to search for tracer
tone or dial tone on a block. This may create an
electrical imbalance on a data line that will disrupt
service. Once you find the voice line you are searching
for then it is OK to test Tip to ground or Ring to ground
on that line.
Be careful not to short the test leads together when
connecting to a data line (or any line for that matter),
as this could bring down the service.
It is best to put the test set in Monitor mode when
troubleshooting a line, searching for capacitance kicks,
RF signals, craft provided tones, etc.
Data Lockout Override Operation
Normally, when the test set detects data, it means the
operator has accidentally connected to a high-speed
data line and should immediately disconnect from the
line to avoid disrupting the data service. But in some
cases the operator must go off-hook on a specific line
even though the test set indicates that the line is a data
line.
The following are scenarios where the operator may
wish to override a data lockout:
•
When there is false data detection due to RF
pickup on a line that is near an AM radio
broadcast antenna. The RF induced in the line may
appear to be data.
•
When performing a ground start, the test set may
generate the data alarm when the Talk/Monitor
switch is in the T position. This is because ground
start lines are unbalanced before startup and thus
are prone to picking up a lot of noise which may
appear to be data to the test set. If this occurs, use
the override function to go off-hook on a ground
start line.
Telephone lines near AM radio broadcast facilities, pick
up the RF signals from the broadcast antennas.
Normally this isn’t a problem for the test set. If the line
is well balanced, the test set will not see the RF signal
because it is a common mode (longitudinal) signal. But
if the line is unbalanced, part of the RF signal will be
converted to a differential (metallic) signal. If the signal
amplitude is high enough, it may be detected as high-
speed data by the test set. If you know for sure you are
on such a line, use the unit’s override capability to go
off-hook.
The data lockout override can be activated only when
the Talk/Monitor switch is in the T position. To activate
the override, press the STORE/PROG key then the TEST
key. If dc voltage is present, the test set goes off-hook.
To go back on-hook, unclip the test set’s test leads from
the line or put the test set into Monitor mode. The
override key sequence must be executed each time you
want to take a locked-out test set off-hook.
