INSTALLATION AND MAINTENANCE MANUAL
LYNX
E1 FAMILY
LICENSED & SPREAD SPECTRUM RADIOS
JUNE 2001
PAGE 4-10
SECTION 4: TROUBLESHOOTING
Recommended Actions:
An internal loopback test should be performed to verify that errors are occurring over the link:
v
Verify that the near-end radio is set for Internal test mode and Latched Error LED (both
default settings of rear panel DIP switch positions, as described in Sections 3.12.2 and
3.13.3).
v
Press and hold (for approximately 3 seconds, then release) the Loopback Enable switch
on the front panel of one radio (this will take radios out of service). Let this test run for a
few minutes.
v
If the ERROR LED illuminates, this is verification that errors are on the link and
troubleshooting should continue.
v
Press the Loopback Enable switch to deactivate loopback mode.
Next measure RSL by placing a voltmeter across RSL and GND test points. Compare this voltage
to the Factory Test Data Sheet and estimate the RSL in dBm. Compare this to the RSL that was
expected using path calculations (see Section 3.3.3). Press and hold the DISPLAY FAR END
button and measure the far-end RSL (while continuing to hold the button). Compare this RSL to the
Factory Test Data Sheet for the far-end radio and estimate the RSL in dBm. Again, compare this
RSL to the expected RSL from the link budget calculations.
If RSL from both ends of the radio are approximately the same as each other, but lower than
anticipated for this installation, then the likely cause of the BER alarm(s) is excessive losses
between the radios. Excessive loss problems could include the transmission line at either end, all
adapters, connectors, the antennas, the antenna alignment as well as the path itself (any
obstructions or clearance problems). Antenna alignment, line-of-sight and path clearance should be
verified; if this does not improve RSL, all devices between the radios and their antennas at both
ends should be checked. Make sure all transmission line, connectors and any other devices are
properly rated for operation at the radio's frequency (2.4 or 5.8 GHz).
If only one end has low RSL, this could be caused by low transmit output power from the opposite
end radio. Verify that the transmitter output power of the radio opposite to the low RSL receiver has
been set in accordance to path calculations, or EIRP restrictions (where applicable). Power
adjustment must be performed by professional installation personnel only. The PWR test point can
be used and compared with the Factory Test Data Sheet, the front panel recessed potentiometer
can be turned clockwise to increase power. If an RF power meter is available, this can be
connected to the RF output of the radio for precision measurement. This test will also verify that the
radio transmitter is working properly.
