Data Lockout Operation; Ground Start; Data Safe Practices - Fluke TS54 TDR User Manual

Data Lockout Operation

With the increase in high capacity data lines in the
distribution system comes the greater risk of disrupting
data services when working on analog lines. The test
set is designed to be used by Outside Plant and Central
Office technicians to perform their normal duties while
greatly reducing the possibility of accidentally
disrupting data service.
Accidentally going off-hook on a data line while
searching for talk battery or dial tone on an unmarked
terminal block or cable splice could bring down a high-
capacity data line. To prevent this, the test set provides
an automatic data lockout function. When you put the
test set in Talk mode then connect it to a Tip and Ring
pair, it automatically tests the line for high-speed data
(data signals that are above the human audio range)
before going off-hook. If the test set detects data, it
locks out and does not go off-hook. A warning beep
Data Detect Lockout
sounds, and
When the test set is locked out, it remains on-hook, it
does not draw direct current from the line, and it
presents a high ac impedance to the line to reduce the
possibility of disruptions to data. The test set can detect
and protect high frequency data services.

Ground Start

Ground start lines are typically found on PBX
installations. To activate an idle, ground-start
telephone line, do the following:
Q
1 Press , and connect the test leads to Tip and
Ring of the ground start line. With a third wire,
temporarily short the Tip side of the line to earth
ground. A wire with an alligator clip at each end is
often used for this. Do not allow clips to short
network connections.
2 With the short to earth ground in place, press
P
. When dial tone is received, remove the third
wire from earth. The circuit is now ready for
dialing.
shows on the display.
How to Use the Monitor and Talk Modes

Data Safe Practices

Always monitor the line for an audible signal before
attempting to go off-hook to draw dial tone. The data
detect circuitry on the test set is designed to detect
data signals above the human audio range. To detect
data signals within the human audio range, such as
produced by voiceband modems and subrate DDS
transceivers, you must listen to the line using the test
set's audio monitoring capability. If you hear the hiss of
a voice band modem or low frequency data transceiver,
P
do not press . If you press
lock out because it does not detect low frequency data.
It will go off-hook and will interfere with the voice
band modem or data transceiver. To avoid this, try
another line or wait until the line is idle.
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 as
follows:
P
1 Press .
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), a warning
Data Detect Lockout
beep sounds, and
on the display. If there is no data on the line, the
test set goes off-hook.
2 If there is no data on the line, you can now dial a
number.
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.
P
, the test set will not
is shown
13