Frequency Selection 900Mhz

I am setting up a new cluster and upon checking spectrum analysis with each AP individually, we are seeing a noise floor of -80 to -83 on all freq’s untill 923Mhz. Above 923 is maxed out at -40.

My question is what three freq’s would be a good selection for the Ap’s?

Six AP cluster w/CMM Micro.

Thanks in advance.


That looks like it is a pretty noisy environment. The AP’s will have a hard time hearing SM’s.

Can you go into the area that you are proposing coverage, and do a spectrum check in the direction of the proposed tower site and see what it would look like in the field in terms of noise floor?

We did that before installing the AP’s. We were mostly checking for any other 900-928 transmitters on or near the proposed tower site.

From the ground, most noise floors were in the -90’s.

What we are trying to attain is the best AP freqs to use on this cluster.

What will work best with only 900-923 usable?

We need three freqs.
How about 906,911,916?

How close to the next door AP can you really get?

Any combination ideas?

Thanks again,

906, 915, 924 are the only non-overlapping freqs. Trying to use freqs closer together will result in poor performance on all of them.

Best solution is to go with 906 and 915 and abandon 924. Use 90deg sector antennas and put N/S on one frequency, and E/W on the other frequency.

Beat me to it Jerry.

Exactly what he said.

I’ll add you need to use quality 900MHz sectors, like something from MTi. Make sure you are running horizontal polarization too.

Thank you Jerry, phreak, I was hoping you would chime in.

What is: N/S and E/W?

North South East West

As long as AP’s are face to face and back to back they can be on the same frequency assuming that they are configured with the same Max distance, Downlink %, and Control Slots.

Got it,