NetStumbler.org Forums

Does anyone know what units Netstumbler records SNR, Signal, and Noise?

decibels.

Actually, they're in two different sorts of units. The signal and noise measurements are in decibel milliwatts and the SNR is in plain decibels. dB is a meausement scale that's only useful for comparing one value to another. In the case of the signal and noise measurements we choose 1mW to be 0 dB and measure from there (hence, these measurements are usually a negative number). In the case of the SNR we are comparing two values directly and it doesn't matter what value is used as a zero for each measurement as long as it was the same. The difference gets lost in the subtraction.

For example:
Signal = -38dBm = 1mW - 38dB
Noise = -96 dBm = 1mW - 96dB
SNR = 38 dBm - -96dBm = (1mW - 38dB) - (1mW - 96dB) = (1mW - 1mW ) + (96dB - 38dB) = 58 dB

But nobody but a hardcore radio geek is going to call you on it if you just refer to everything as dB.