I have read in many posts here in these forums where a person is encountering problems with changing signal strengths on point-to-point connections.
One of the issues on any link (keep this in mind when aiming a link!) is as the receive rate increases, the receive sensetivity of the card decreases and as the transmit rate increases the transmit power reduces. Thus a link where both sides of the link are set for max transmit power will almost always show a stronger signal at a 1 or 6 meg connection and will show a weaker signal at an 11 or 54 meg connection. ((( As rates increase signal strength decreases ))). Look at the specs of the wireless card for transmit power at the various transmit rates and also look at the receive sensivity at each rate.
If you are aiming a point-to-point antenna and want the best possible aiming performed then try this:
-Set both radios for a 1 or 6 meg transmit rate only. Lock in the slowest rates possible on both radios. You want to turn off all rates but the slowest rate on both radios.
-Now aim your antennas
-After aiming is complete, document your signal strengths and signal-to-noise levels on both radios.
-Now go ahead and turn on your faster rates on both radios and then document your signal strengths and signal-to-noise levels on both radios and also note what speed your signals were at for what rate each radio transmit rate is at.
Example - take any point-to-point link and lock it into 1 or 6 meg for both radios then document your signal levels with max tx power setting - then lock both radios at the fastest rate the link can stay connected at then document your signal levels. You will almost always see weaker signal levels at the faster rates.
So, if you are seeing changing signal strengths on any connection - be sure to take into account the rate each radio is also using when you look at the signal levels on both radios.
A weaker signal strength is not always a bad thing - you need to also look at the connection rates and SNR on both radios to get a good grasp on your signal quality.
Tom Jones - a WISP up here in North Idaho