Trouble Shooting Guide

Axxcelera Broadband
Troubleshooting-Installing an RF link - 13 - Issue: 5.3.x
Rev 2
5 SU signal quality
After you have adjusted the SU to receive a good RSSI you will want to look at the quality of the signal.
This is done by using a few commands at the SU.
Procedure
1. Check the quality of the signal (not the strength) by looking at the hmm modem mmse. This take
1000 samples of the modem mean square error rate, and report the average and the number of
samples over 50. See chart below to identify if out is good or bad. For more information on the
hmm modem mmse command refer to Modem mmse section.
2. Check the PER (Packet Error Rate) by looking at the hmm mac stats. The numbers themselves
don’t actually tell you anything it is the number rxmissed and rxbad versus the number rxok for
the downlink. For the uplink look that the number of CELL TX versus the number of CELL tx
(next row on left side highlighted in yellow). For information on what each column means refer to
the Troubleshooting an RF Link document. For more information on the hmm mac stats command
refer to the Mac stats section.
3. C
heck the Path loss in excess of Free Space Loss by looking at the hmm link status command. This
calculation is a result of the difference between the expected RSSI that the SU and the actual RSSI
of the SU. This should be no greater than 10 dB and should be as close to 0 as possible. Any
number around 5 is just fine though. For more information on the hmm link status command refer
to the Link status section.
Status Average Value Samples over 50
Good <20 0
Marginal 20-35 1-30
Poor 35-50 30-50
Bad >50 >50
192.168.3.254 hmm> modem mmse
running please wait
0 out of 1000 mse's > threshold 50
mse average 15
192.168.3.254 hmm> mac stats
RXOK RXMISSED RXBAD TX
FDHDR:
111296 0 0 0
RGR: 111296 0 0 3294
ACK:
3575 0 0 3564
CELL: 9732 0 0 9877
tx 9877, inseq 9732, miss 0, dup 0
ticks (20mS) since last: utopia tx 0, utopia rx 0, FDHDR RXOK 0
free list: head 921 tail 253 (delta 668)