Trouble Shooting Guide

Axxcelera Broadband
Troubleshooting-Installing an RF link - 40 - Issue: 5.3.x
Rev 2
15 Modem rxdc stats
The “hmm modem rxdc stats” command can help to spot intermittent problems with radio links. It displays
the number of times the receiver dc offsets were recalibrated, and for what reason, e.g.
AP/SU modem rxdc stats
192.168.100.200 hmm> modem rxdc stats
TRIGGER : TEMPERATURE FDHDR ERROR CELL ERROR ACK ERROR
FREQUENCY : 1 0 0 0
OFFSET : MIN MAX
I : 0 0
Q : 3 4
The stats can be reset to zero with the “hmm modem rxdc stats z” command.
Recalibrations are required when the temperature changes, and may occasionally be triggered by errors
when the offesets change without a temperature change. However, because the recalibrations are triggered
by a high error rate in any one second interval, the rxdc stats tend to show intermittent radio problems that
may not be obvious from the MAC stats (because the average error rate may be low). As a rule of thumb,
error-triggers should be less than temperature-triggers. If the number of error-triggers are more than ten
times the number of temperature-triggers then there is a definite problem with the received signal. Where
an AP has a poor signal at its receiver (due to interference or a power-control issue, for example) then the
error-triggers are typically one hundred times the number of temperature-triggers. Once a calibration is
triggered by errors there is a 1 minute delay before it can be triggered again. Therefore, as an example, a
unit with an uptime of 10 hours (i.e. 600 minutes) and a total of 600 error-triggered rx dc offset calibrations
means that high error rate was always present.
The “hmm modem mmse” and “hmm modem msreg 6” commands can be used to confirm a problem, and
diagnose a possible cause.