User Manual

INSTALLATION AND MAINTENANCE MANUAL
LYNX.sc E1 FAMILY
SPREAD SPECTRUM RADIOS
OCTOBER 1998
PAGE 2-14 SECTION 2: PRODUCT DESCRIPTION
2.3.4 Controls
Loopback is a test method used which transmits either an internal or
external E1 test signal and loops this E1 signal back at the far-end radio (re-
transmits the signal back to the near end). The near end then receives the
signal. This is very useful for testing because the test signal can be
monitored at the near-end and the quality of the entire link can be measured
using a Bit Error Rate (BER) test, or internal test features, without anyone
going to the far-end radio location.
ERROR
When lit RED, this indicates that a bit error occurred while in loopback mode. If you
are not using a BER test set, this LED may be observed to determine if there are
any bit errors during loopback, for example during an overnight test.
ENABLE
This is a push-button switch that executes the loopback mode for the corresponding
channel. Loopback is initiated by pressing and holding this switch for approximately
3 seconds. Once in loopback mode, the LED which is embedded in the switch is
illuminated YELLOW to indicate that Loopback is ON. The LED on the near-end
radio flashes while the far-end is solid. Loopback is disabled by pushing and
releasing the ENABLE button at either the near-end or far-end radio.
Enabling loopback will interrupt traffic. This is an out-of-service test.
CH SEL
This is a push-button switch provided only one the 4xE1 version that selects the
channel for loopback mode. The channel is determined by the number of times the
switch is pressed. Press (hold for 2 seconds and release) for channel 1, press again
for channel 2, press again for channel 3 and press again for channel 4. Loopback is
initiated using the ENABLE switch; the LED in the CH SEL button flashes in a group
sequence to identify which channel is selected for loopback.
DISPLAY
FAR END
This push-button provides the capability to determine alarms and status of the far-
end radio. When pressed and held, the alarm and status LEDs and the RSL test
point correspond to the far-end radio’s status and RSL value. This can be used for
installation, maintenance and troubleshooting. When the LED on this switch is
flashing, no far-end information is available. This typically indicates that there is no
link between near-end and far-end radios.