Signal and Noise rundown

Could some one give me an insite on what exactly the Signal and Noise are, what the measurement whats good/bad and ways of improving it.

Thanks

This is how I understand it:

signal is the total signal strength received, i.e. -70db, then you have your noise which may be -90db

SNR or signal to noise ratio is then 20db, which is the difference between the signal and the noise

Ideally the bigger the SNR the better and the bigger the signal the better (i.e. -60db is better than -70db)

These can be measured with a program called netstumbler

You can increase signal strength by using an antenna with a high gain, use a higher powered card (also increases noise) or reposition the antenna so it has a better line of sight with the antenna you're connecting with (this may cut noise and boost the signal)

Hope this clears things up a bit

so raising my router an extra 5cm which gives a gain of 10-15db is well worth it?

I would say 10-15db increase would be worth it

When you say a higher power card increases noise as well as signal, does this apply for boosters and/or high gain antenna as well?

so how much is to much noise, ior what is a good ratio?

high gain radios do not necessarily increase noise, but any amplifier will. higher gain antennas will increase signal strength and cut back on noise.

i would say a good snr is ~20db

It's been my experience that most radios will need at least a 12-15dB SNR for the link to work properly. ANything above 20dB SNR should work just fine. Of course the more the better (as previously mentioned).

Now sometimes "noise" doesn't always show it's ugly face in Netstumbler. Netstubmler is pretty good at finding APs but it really doesn't do well as a Spectrum Analyszer.

Michael

Yes, but not everyone can get their hands on a Spectrum analyser :P

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