Customer High Gain - not receiving expected modulation

Running the Spectrum Analyzer from a 450i AP towards a specific SM. We are running 20MHz channel centered at 5740.

Also ran a Spectrum Analyzer on the AP itself and received this output


From what I understand, the SA with the AP looks clean and the Remote SA from the SM is pretty much only picking up the AP.

The customer has a High-Gain and is shooting down onto a 450i that has has been equipped with a KP Performance Omni Antenna. LinkPlanner shows an expected modulation of 6x but the client is actually only receiving 2x MIMO-B or is modulating in MIMO-A .

SM Link Status:

It seems to me the SNR is low, hence the lower modulation. It is my understanding this link does not have trees in the way. What might help increase the SNR in order to obtain a higher modulation?

Does the customer have a 450b High Gain SM? At 1 mile or less as link planner indicates I would expect the signal to at least be in the 50’s. In my experience when a tech calls in and I am seeing what you have listed here there is an obstacle in the way or they are pointing at an incorrect tower.

I have also seen something similar when the AP was running 15.2 and the SM was 15.1.x.

It is nice if you have it all in cnMaestro and you can quickly look at all the customers in the same area and compare.

Hopefully that helps.

1 Like

Hello Sir,

this is a sign of mis alignment either at the access point or the client side if you know that there is no obstacle on the way:

Check on this.

Sincerely yours,

Niragira Olympe

Thank you for the help.

Checked cnMaestro and there are about 20 customers on the AP. This customer and one other customer have low LQI. The second customer is about 500 ft in front of and below this customer. Installer says nothing blocking line of site.

The same customer posted in the screenshots now has a -9.0 dB signal strength ratio as compared to the -1.0 in the pictures. The 450i AP has an omni antenna - could this be causing the wide fluctuations in signal strength ratio? The installer has not physically touched the radio this week. Only other time I have seen such wide fluctuations is interference, but so far the AP and SM do not see any interference.

Hello Sir,

I thought you had a sector antenna with 16 dBi gain at least. Yes, an omni directional on top of a hill might not be the best option, you need a down tilt or an AP inclined towards the client, hence, you should change the AP and use the PMP 450i integrated radio with 90 degrees beamwidth or go for 120 degrees beamwidth.

Sincerely yours,