On 1/28/2012 17:05, Scott Reed wrote: > RB433AH with XR5 at each end. > Signals running around -69/-71. CCQ is the goofy one. Most of the time > one direction is in the 50% range, but varies quite a bit. The other > direction ranges from 16% to 100%. Generally if I see it getting close > to 100% I know the link is going to drop. It comes right back up, > usually at about 50%. > I have tried 20MHz channels, 10MHz channels, 5MHz channels with about > the same results from all. > I have tried 5.2-5.3 frequencies and 5.7-5.8 frequencies. The higher > frequencies work better, but still not well. I'm not that familiar with the ubiquiti products, but from the data sheet the radio will put out 23 dBm and requires a -74dBm signal to work (the data sheet does not say what channel size this measurement is from, I'll assume a 20 MHz channel).
What strikes me is your normal RSL is is only 3dB more than the min RSL needed to link at 54 mbit/s. This is well within the normal variance of a radio path (+-3dB), and could be causing the radios to switch back and forth between data rates (only after taking some errors). It could be interference, but even 3dB of on channel interference is enough to raise the noise floor and lower your S/N radio (keep in mind in a ofdm radio the RSL numbers given assume a perfect noise free system, for ever dB of noise you have add a dB to your RSL). If you want a 54mbit OTA rate you need a much better signal for it to be reliable. If you need no less than a -74dBm signal, ensure you have a -60dBm or better signal (rule of thumb) during steady state operation. This will give you some head room for changes in the atmosphere (K value) and other issues that pop up from time to time. If you suspect interference, try to figure out if it's local or remote and where it's at. If you can use a HP dish to knock down off path noise, do it. When I was deploying backhaul radios in unlicensed space, I made HP dish's standard on all my links. Unfortunately this is not cheap to do things properly, but it will let you sleep easy at night. -- *Bryan Fields* *APAC Imports LLC* Phone: 800-721-6502 Fax: 727-493-1511 http://apacimports.com
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