High RegFail

We just installed 3 900MHz APs and having strange problem.

AP1 pointing directly to SM has RSSI>2000, PWR>-55, Jitter<7, has 100%down/50%up link capacity, and has the highest RegFail causing frequent lost connections.

In other hand AP2 pointing 120* away has steady connection with 0 RegFail, has 100%down/100%up link capacity at RSSI<1680, PWR<-60, Jitter<7.

Lowering SM’s power to 20dBm, it won’t connect to AP1, but connects steady with AP2.

Questions:
1) Do you think AP1 is defective?
2) Is it normal for SM’s to connect to lowest frequency first rather the strongest signal? Notice all SM’s try connecting to 906 instead of 915 or 924, unless I force it.
3) Why is there difference in reports between AP and SM? AP shows 4000 feet while SM shows 1000 fet, AP’s RSSI/PWR/Jitter are different from SM’s.

My setup is integrated SM’s and 3 connectorized 9000APC’s on 70’ tower. Currently, has only 3 SM’s on field (all within 1.5 miles) and can’t seem to get anything work properly.

have you ran a spectrum test yet? maybe what looks the strongest isnt on both ends.

you could try putting the freq that they like on the AP that the sm should be registered to and see if that resolves it. this will cause down time to your customers and you should only be done by your rf engineer so you dont create self interference problems.

With one AP powered on at a time, I have ran spectrum analysis, and assigned the best possible frequency to each APs. 906 (-86 / -78), 915 (-73 / -69) and 924 (-66 / -62).

924 is facing directly to the SM, it works fine if changed to 906. I cannot keep the 906 to this AP because of other SM will only connect to the AP2 with 906. But this 924 has highest RSSI and PWR with average jitter of 7, which should be resonable. So I don’t understand why upload link capacity is less than 50%.

Are your all your setting identical on each AP? Downlink ration, control slots, Max Range?

are they sync’d together?

First, I’d set the SM fequency to the respective AP’s frequency.Having more than one frequency selected on the SM can cause problems.
As for the low uplink, that could mean the SM’s transmit signal is being obstructed or reflected. Is there anything close to the SM? If this is the case, the downlink would still look good.

Frothingdog.ca wrote:
Are your all your setting identical on each AP? Downlink ration, control slots, Max Range?


Yes. All 3 AP's have exact same settings. I don't know what "control slot" does, but they are all set to "0".
vince wrote:
are they sync'd together?


Yes, they do everything normal like it should, except for the uplink being less than 50%, and frequently losses sync if I turn on 2x or reduce the power out to 20 or less, although no problem on other AP.
kk6mm wrote:
First, I'd set the SM fequency to the respective AP's frequency.Having more than one frequency selected on the SM can cause problems.
As for the low uplink, that could mean the SM's transmit signal is being obstructed or reflected. Is there anything close to the SM? If this is the case, the downlink would still look good.


I have tried SM frequency to just one respective AP's to force connection to it, otherwise it will always connect to the AP set to 906. But it didn't make any difference in uplink, and still losses sync on 2x or less than 20dBm pwr out on SM.

If there is an obstruction or reflection of SM transmission, shouldn't it do the same on other AP? When the SM is set to freq of another AP pointing other way, it's down/up is both 100%.