GAI-Tronics LE200, LE200-FSR, LE200-FLR Page/Party Line Extenders - Manual (Page 15)

Pub. 42004-701L2F
M ODEL LE200 S ERIES W ALL -M OUNT P AGE /P ARTY
®
L INE E XTENDERS P AGE 13 of 50
f:\standard ioms - current release\42004 instr. manuals\42004-701l2f.doc
04/09
Operation
The Model LE200 Page/Party ® Line Extender requires no user interface after successful installation and
testing.
Description of Features
Page Line Audio Transmission
A pair of Model LE200s provides page line audio transmission between two Page/Party
®
system cables.
This transmission is half-duplex operation.
Half-Duplex Operation
When the Model LE200 detects a peak audio level equal or above a Peak Voltage Level Detection
Threshold , it immediately switches audio “on” in that direction for the Transmission Direction Hold
Time. Audio from the other direction is muted and ignored during that time. Audio is not switched “off”
until it is continuously below the Peak Voltage Level Detection Threshold for the Transmission Direction
Hold Time. The DIP switch, SW2, located on the Main PC board selects Peak Voltage Level Detection
Threshold and Transmission Direction Hold Time. Refer to Table 8 and Table 9 for switch setting
options.
Training the Echo Cancellation
Overview
Line echo (also known as electric or hybrid echo) is created by the electrical circuitry connected to a two-
wire (full duplex) audio system. Echo is inherent in all full-duplex audio systems and is affected by the
audio line length and line impedance mismatches. The presence of audible echoes results in undesirable
audio quality. This kind of quality degradation is inherent in the network equipment and end-user phone
devices.
To minimize echo, the Model LE200 performs an echo cancellation training sequence on party lines 1
through 5. The echo cancellation training takes approximately 15 seconds and is performed automatically
one minute after power is applied to the LE200. This delay allows all power levels to stabilize prior to
performing echo cancellation training. Echo cancellation can be manually initiated as described below.
N OTE : Signal impulses are transmitted onto the audio lines during the echo cancellation training
sequence. Handset stations that are in use on a party line will hear the signals in the handset receiver. For
troubleshooting purposes, the one-minute delay may be disabled by closing DIP switch SW6-1.
Manual Initiation of Echo Canceling
Press and release push button PB1 on the main PC board three times. The push button must be pressed
for at least one quarter second and no more than two seconds each time. The timing requirement is meant
to prevent accidental requests. If an error is made with the push-button timing, the sequence must be
repeated from the beginning.
The main board LEDs will indicate the progress of the echo canceling sequence. One column of LEDs
turns on after each push button press or release until the sequence is started. Once the sequence is started,
those LEDs remain on, and a countdown timer is displayed on the remaining LEDs. The LEDs return to
normal operation after the echo cancellation training sequence is complete.