|The LBT is a Bit Error Rate Tester
for testing synchronous or asynchronous modems and other DCEs. Testing
can be conducted over full duplex or half duplex links. The LBT can also
test modems connected in multipoint configuration for polling operation.
A network with up to 32 slave modems is supported.
The LBT operates synchronously or synchronously at
data rates from 75 bps to 38.4 kbps. When operating in synchronous mode,
five test patterns are available: 511 or 2047 pseudo random, 7 space 1
mark, 7 mark 1 space, or alternating mark/space. In asynchronous and
multipoint modes, only the 511 bit pattern is available.
When testing a DCE, a loop is performed, sending
the data back to the LBT. The LBT compares the received data with the
transmitted pattern and presents the result on an LCD display, counting
bit errors, block errors and error-seconds. The LBT also features an
INJECT ERROR push button which enables the user to check the tester and
the line by introducing errors in the transmitted data stream.
Block sizes can be set to 512 bits, 1000 bits,
1024 bits, 2048 bits and 10 kbits. When testing multipoint, a block size
of 512 bits is used.
The LBT can generate its own clock or receive
clock from the connected DCE.
Set-up and operation are initiated from the front
panel using soft keys and an interactive menu selection on an LCD
message display. Ten indicator LEDs display the activity of the
The LBT comes in a convenient hand-held case. The
unit is powered by a detachable external power supply unit.