RULES:
a. Find the best signal strength you can.
b. Try to get the BEST Tx/Rx CCQ (100% is the best scenario) > when it drops below 93%, you will NOT able to get max throughput data.
c. Try to get the BEST S/N (bigger numbers are ALWAYS better) > 60dB is ideal.
GENERAL EXPLANATIONS (in "flat - undertanding - language"):
a. The best SIGNAL means that you are aligned and OK -
BEWARE: In "Wi-Fi world" ("digital world"), you
MUST have from -50dB and below (-60dB to - 50dB is ideal) because afterwards (in case of -40dB - for example), the receiver gets "overfilled" and produces its own "intermodulation distortions" which has finally an impact of downgrading data throughput.
Some of the best and "intelligent" (highly cost - professional) links out there, when their receiver "sees" high signal in its input (-38dB - for example), AUTOMATICALY drops down its Tx power in both ends to get approx. -51dB. Problem with some of them is that you can't alignment right, except from some of them that they have the alignment option, which drops to MANUAL and when you're done, it goes to AUTO itself.
b. Tx/Rx CCQ means (in general words and not to put you in deep waters with transmitting digital signal) that your Rx signal has the quality provided from Tx and visa-versa. The BEST (ideal quality) is the 100%. This means that your signal is perfect (or almost perfect). When it drops lower than 90%, problems will start and firstly by dropping frames (data throughput). So we take care to have our Tx/Rx CCQ
OVER 92%.
The digital signal is like a "table" - Starts from zero, goes up to its power, on its transmitting power MUST BE FLAT at whatever MHz bandwidth we have chosen, and when it ends, goes down.
IF the upper "line" is not
FLAT (it might be like a wave or something), we encode
QUALITY problems.
IF the upper "line" has side lobes higher than -35dBc (this is due to VERY high output RF power which its amplifier can't handle and it intermodulate producing errors), we encode quality problems as well.
c. IF our signal is too low, the receiver "reads" it BUT it also "reads" the noise that exist and if we have a signal of approx. -67dB (40dBuV) and our Tx is already in very high power producing its own intermodulation, we will encode problems with frame drops - data throughput.
IF we encode such a scenario, it will be wise to DROP the bandwidth (by lowering its MHz bandwidth) of our link to get a "more stable connection" (OR drop its output RF power in case that we have a good signal).
EXAMPLE for S/N with SIMPLE WORDS - "flat explanation so everyone can understand":
Let’s suppose that we have a receiver which has a -77dB sensitivity by its own.
By adding to it a dish of 30dBi gain, our Rx sensitivity goes down to -107dB.
In such a scenario, we
HAVE to have a worst signal of -67dB to be 40dB over noise level and our signal to be stable - somehow - , supposenaly again that our Tx power is CLEAN from its intermodulation distortion (we have NOT pushed its output power to its limits).
By ALL of the above, we can safely say that on a Wi-Fi link we NEED:
a. SIGNAL strength from (worst case) -70dB to -50dB rage.
b. Tx/Rx CCQ (quality) from 92% and ABOVE with 100% ideal target.
c. S/N (Signal to Noise) OVER 40dB with best scenario 60dB.
By having these
three ALIGNED TOGETHER, we are sure about our link.
Thank you very much,
George.
* shi(f)t!!!......I wrote a lot!!!........
.