User Manual

INSTALLATION AND MAINTENANCE MANUAL
LYNX.sc E1 FAMILY
SPREAD SPECTRUM RADIOS
OCTOBER 1998
SECTION 4: TROUBLESHOOTING PAGE 4-17
4.7 Errors in the Data Stream
When the radio is in service, errors in the data stream may occur. This is usually known to the
operator by either faulty data indications of downstream equipment, external bit error rate testing,
or ERROR LED indications during internal loopback testing.
During internal test mode loopback testing, if an error is detected, the ERROR LED will illuminate.
In default mode, this lamp will stay lit during loopback testing if a single error is detected. If
Loopback has been performed over a period of time and the ERROR LED does not latch on, the
radio link is operating completely error-free.
The ERROR LED only operates in internal test signal loopback
mode. Use a BERT to detect errors when using an external test
signal. See Sections 3.12.2, 3.13.2 and 3.13.3 for more details.
It is possible that no alarms appear on the front panel during normal operations, but there are
errors present in the data stream. If the BER LED is lit, this indicates rather severe error
conditions and it is best to follow the procedures provided in Section 4.6.1. However, some errors
will not result in the BER alarm (such as bipolar violations, slow "dribbling" errors, improperly
terminated CEPT-1 connections or incorrect settings of switches), but will be exhibited on
downstream data processing equipment or during a BER test. In other cases, there may be data
errors due to atmospheric conditions (fading), interference or other reasons, but not at a high
enough error level to be indicated with the BER alarm LED. In the case of these types of errors,
the following information can be helpful to troubleshoot the radio link.
Indications:
❖ In Loopback Mode, ERROR LED is illuminated
❖ During external BER test, test equipment indicates errors
❖ Downstream equipment (mux, channel bank, CODEC, router, etc.) indicates errors
Possible Causes:
❖ Path fading due to atmospheric conditions
❖ Poor transmission line connections
❖ Antenna problems, misalignment or path clearance
❖ Received signal level (RSL) is too strong
❖ Far-End radio transmitter circuitry is faulty
❖ Near-End radio receiver circuitry is faulty
❖ Interference
Recommended Actions:
1. Verify CEPT-1 wiring in accordance to Section 3.11.
2. Even if the BER alarm LED is unlit but errors continue, follow the instructions described in
Section 4.6.2