Space from noise floor

How much space between the spectrum analysis noise floor and the dbm level and what the SM sees do you say an installer should shoot for? At least 5 dmb? 10 dbm?

3dBm carrier-interference ratio is what motorola suggests for a 10e-6 which is 1 bit per 100,000. or something like that. and in 2X mode you need a 10dBm c:i ratio. realistically you proably don’t want to put up an AP where your competitors are blasting you to within 3dB on a lot of your customers, because it just gets worse.

AH! the information given and the questions are mixed up or could be mistaken.
Let me try to clear some of it.

I would say that twinkletoes is correct, but the analisis is base on the “noise floor” not on the peek signal level.

If your noise floor is -90db and you have peek hits of … say -83db. Then at that point ( If using the same frequency ) it would be nice to have +3db or +10 db of margin. I would use +15 db, because you don’t know what you will have in the future ( Competitor or just new devices on that frequency ). That’s a signal level of -68 dbm in this case to be on the safe side.

I know this sounds funny, but using the Canopy Spectrum Analyzer, one could make a mistake on what the noise floor is. In any case, for what we all do using Canopy, we must look at the peek, or highest signal level.
It would be nice and ethical if we all respect someone else signals. But other manufacturer do not have built in Spectrum Analyzer, and worst, good installers. That’s why, ( and some others ) we have interference.

I think, not sure, that Ben at Motorola Tech Support, told me that Canopy 900MHZ only need 1 db of margin.

Keep in mind, the canopy units re-register if the signal is “NOT GREAT”.

1 db… no I find that very difficult to believe… ( i could be wrong) but I would be amazed if it is true… would want to understand how they pull that one off…

I know orthogon or poin2point units get away with 2.5db