User's Manual

D–1
070-20000750-01 Rev A
Appendix
D
RF Signal Quality
Parameters Description
Burst Error Rate Cumulative burst errors (uncorrectable FEC errors + No Unique Word
errors) as a percentage of total bursts received. At BSU, a value of
1% in a sector is normal. Higher number may caused by problems
such as interference and can degrade performance.
Correctable FEC Error Count Number of bursts with errors that are corrected by FEC (Forward
Error Correction). This is a normal part of system operation.
Uncorrectable FEC Error Count Number of bursts with errors that can not be corrected by FEC,
resulting in such bursts being dropped by the system. If this number
is high, the link is likely to be impaired by either low SNR (link is too
long), multipath, fading, or interference.
No Unique Word Count Number of burst with no unique word (an identifier in the preamble
of each burst). Mainly caused by external interference and thus it
reflects the quality of the channel.
At BSU, a high number of No UW Count will degrade performance of
the sector. It can also be cuased by packet collision during Conten-
tion Request but such occurences are rare.
At SU, No UW Count can also caused by the SU beig too close to the
BSU, resulting in overdriving of the SU radio. This can be confirmed
if Installation Manager reports signal level higher than -40dBm. In
such case, the SU antenna should be pointed up toward the sky.
Signal level between -45 to -83 dBm is preferred.
No Energy Count Caused by a scheduled packet failed to arrive or arrived with power
level below threshold.
At BSU, this count will keep increasing as part of normal system
operation.
At SU, a low count number may result from fading and can be
ignored if the performance is normal. However, a high count num-
ber indicates very low signal level. Installation Manager should be
used to point the antenna again to make ensure proper power level.