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I use Google for hours but I do not find a satisfying answer how to interpret the captured signal strength, given by the radiotap header. For instance Wireshark shows me a SSI Signal of -52 dBm and I want to convert it to a linear representation/unit. For me, a sensible unit would be the signal power at the antenna in Watt oder mW. Is it possible to convert this -52 dBm to mW?

Some background information: I implement a WLAN-based localisation and want to estimate the position of APs by combining some reference points and the measured signal strength. With the help of triangulation, this should produce a rogh map of the environment.


asked 26 Dec '11, 15:51

EyDu's gravatar image

accept rate: 0%

If that value comes from a radiotap header, then the signal-in-dBm is defined by the radiotap specification as "a single signed 8-bit value, which indicates the RF signal power at the antenna, in decibels difference from 1mW", so, as per the formula in the Wikipedia page for dBm, power = 10^((dBm-30)/10), so -52 dBm is 10^((-52-30)/10) W, or 10^-8.2 W, or .0000000063W, or .0000063mW, or 6.3nW.

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answered 27 Dec '11, 02:45

Guy%20Harris's gravatar image

Guy Harris ♦♦
accept rate: 19%

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question asked: 26 Dec '11, 15:51

question was seen: 6,785 times

last updated: 27 Dec '11, 02:45

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