Joined: 18 Jun 2006 Posts: 1110 Location: Kiel (54.4247,10.1721)
Posted: Tue Aug 01, 2006 22:57 Post subject:
Signal -> Low is good (well -1 is good, -98 is bad, mathematically -1 is higher than -98 but you know what i mean because you asked for ignoring the minus)
Noise -> High is good (-98 is good, -1 is bad)
SNR -> High is good (should be the same as difference between noice and signal)
Signal Quality -> High is good (somehow like SNR but indexed to 100 with noise as base, percentage of the best theoretical available qualiry regarding to your local-noise, difficult to explain *g*)
Edit:
Regarding to one of my WRT's I will state an example, keep in mind that some numbers are rounded for output by the driver but internally kept with some more decimal places...
Examples would be:
Joined: 07 Jun 2006 Posts: 980 Location: Coal Creek Canyon, Colorado
Posted: Thu Nov 08, 2007 20:09 Post subject:
negative numbers and logarithmic ratios leave a lot of people in the dust...
SNR is all you really care about (unless it's really low like below 10, in which case signal and noise need examined for optimization)
double-digit SNR will get you megabit thruput
I've seen a table somewhere detailing the SNR required to hit specific 802.11G link speeds (btw link speeds <> thruput)
the "percentage" isn't meaningful in practical terms - it only exists cause it's easy to graph. ignore it. _________________ linksys GSv2, Gv4, Gv2, GLv1, G-TM, Buffalo wbr2, whr, whr-hp, whr-g125, wli-tx4-g54hp, Moto wr850gp, Alix.3C2
To elaborate a little, any number with dB after it means it is on a logarithmic scale. To get the SNR you would divide signal by noise, right? Well, yes, but remember that when working in a log scale you are basically dealing with an exponent, so where you would divide:
SNR = n^SIGNAL / n^NOISE
in regular, non-log world, you actually end up subtracting the exponents. Try it:
2^8 / 2^6 = 256/64 = 4 = 2^2 = 2^(8-6)
This is what you must do in log world to get your ratio, i.e. to get SNR from numbers in dB simply subract them:
SNR (dB) = SIGNAL (dBW) - NOISE (dBW)
Also, when a dB number is negative, that means it is less than 1:
0dB = 1
-1dB = a little less than 1
-99dB = almost 0
so you want your signal to be close to 0dB and your noise to be close to -99dB or lower
This brings me to my question, what does the noise reference setting do? Is this just used to calculate that useless percentage for signal strength?