Hello Members. I hope you doing well. I have two cases that I need help and suggestions.
Case 1:
I have my LHG 52 ac as client set to wireless mode “station” which is used to connect pppoe-out to the other access point.
My case is that when my signal strength becomes (-32 to -35) the RX CCQ drops between (29% to 35%) even when load. In comparison, when the signal strength becomes between (-40 to -45) the RX CCQ is between (92% to 100%). When there is no load the RX CCQ is stable at 92%.
The other end distance is less than 1km and the Signal to noise is between (57 to 62).
The frequency mode is set to regulatory domain.
Case 2:
About the wireless signal strength difference between vertical and horizontal.
The current Rx signal strength is between (-42 to -45) while the Tx signal is between (-68 and -72)
Below is the signal strength from chain0 and chain 1:
Chain0:
-71/-43 dBm
Chain1:
-70/-48 dBm
When signal strength is too high, receiver gets overwhelmed and percieves increased noise level. Solution is to do something to decrease signal level to a bearable level, usually thats around -50dBm (or slightly better, around -45dBm).
Technically: receiver needs certain signal level do successfully decode signal. And levels coming from antenna are usually too low so there’s a preamplifier between antenna and receiver. That amplifier has variable amplification factor so that signal level coming out of preamplifier falls into decodable range. Amplification is controlled by function called Automatic Gain Control (AGC). However, preamplifier has a limited range of amplification factor (both low and high). If signal level from antenna is too high, AGC can not decrease amplification low enough and output levels get clipped. This can severely distort signal making receiver hard time to decode/digitize it. On the lower end of signal range, amplification of preamplifier might not be enough, problem is also that preamplifier amplifies noise and interference, it also adds own noise (as every analog device it’s creating thermal noise), so receiver may not be able to decode signal due to too low SINR.
What you can do: decrease Tx power on the side opposite the one with too strong reception, aim for highest signal strength giving you 100% (or close) Rx CCQ.
Signal levels can be asymmetric for several reasons, but most prominent one is different antenna gain. Tx power on directional (high gain) antenna is limited due to country regulatory limits (EIRP, which is sum of Tx power and antenna gain), so EIRP may be the same for both ends of a link. However, antenna gain works for reception as well. If one end uses omnidirectional antenna with low gain (e.g. 0dBi) while the other end uses highly directional antenna with high gain (e.g. 20dBi), then the difference in received signal strength on both ends will be very notable (equal to difference in antenna gains, e.g. 20dB).
Another pissible reason is if one end transmits with much lower power for some reason (failed Tx amplifier, too weak Tx amplifier, settings). Apart from settings I don’t think this is the case in your case, 1km link suffers from decently high pathloss and yet your Rx signal levels are not too bad.
Note that signal strength measurements are less precise if Rx is very strong (e.g. above -45dBm) or very weak (below -85dBm).
It’s normal to see difference in Rx signal for different polarizations, reflection surfaces turn polarization plane, obstacles can be polarized as well. And not the last reason: atmosphere does not attenuate all polarizations equally (but this amounts to a few dB).