We have two 1410 bridges about 400 meters apart, clear line of sight, one with the 22.5 dBi internal panel antenna and the other with a 9 dBi omni, both vertically polarized. The signal strength seems low to me: -74 to -78 dBm on both ends. The link test typically shows "POOR" with 35% to 70% retries.
What signal strength should I expect with properly configured and installed radios that are 400 meters apart?
What signal strength is required for 99.99% or 99.999% reliability?
One 1410 has the integrated antenna and is mounted for vertical polarization (cable connections out the bottom), not pointing upwards. It is aimed at the omni antenna which is about 400 meters away.
The other 1410 has an external omnidirectional antenna mounted the normal way so that it is also vertically polarized.
We were seeing signal levels of -78 and -76 dBm which generated a link test result of "POOR" with 35-80% retries and lousy throughput.
We eventually tried replacing the omni antenna and coax, and now have signal levels of -56 and -54 dBm and a link test result of "GOOD".
My question is what signal strength should we expect on 1410 radios that are 400 meters apart using a 9 dBi and 22.5 dBi antennas? (My problem is a lack of experience, so I didn't know that -78 dBm was 20 dB or more below what we should see.)
And what signal strength is required for 54 Mbps with 99.99% and 99.999% reliability?