TechIdiots Forum

Hello Andrew,

I've been toying with Vistumbler for a while now. I know that netsh gives the signal strength information in % but how do you come up with the dB estimates (is it dB or dBm)? Any particular formula that you used? I tried fitting the numbers but it seems it is a bit non-linear, especially near 0% and 100%. The numbers fit perfectly most of the time though. Another question I have is the signal history information in the log file. It looks like it is updated every second or so. How can I update the signal strength history, say every 100ms? Is this even possible?

At first, I'm assuming the signal history is updated based on the auto refresh network feature turned on and set to 1sec. I tried changing the refresh time to 500ms and 2sec but it seems that the signal history still updates at around 1sec. There goes my theory Hope you have better explanation.

ya...right now to % to db estimating is a terrible hack

it was originally based off a formula here (http://en.wikipedia.org/wiki/Signal-to-noise_ratio). Unfortunately since I'm not really sure what MS uses to come up with that % value and i have no signal to noise ratio, that did not really work well

I ended up messing with that formula until I got something similar to results netstumbler was giving me on the same hardware. So my current formula is this $EstimatedDB = Round(-70 + (20 * Log10($InSig / (105 - $InSig))))

I am always open to suggestions on making a proper conversion, so if you know something i don't...please let me know

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Testing every 100ms is probably not something you are going to be able to do easily. netsh just does not update that frequently. Also, Vistumbler takes about 200ms to go through a loop (if you turn down the refresh time), so you will never be able to update faster than that.

I don't recommend using under 1 second for updating, but you can always try. It sounds like you did it correctly.
you would want to lower the "refresh loop time" on the main settings page and lower the "auto refresh network time" on the "Auto" tab

Thanks for the information.

I remember reading something on RF signal strength measurement not being standardized between various NIC manufacturers, so any absolute dBm/mW values will not be consistent/accurate. This means converting the percentage to dBm will depend on how the NIC manufacturer decides to report the signal strength information. I guess there isn't a unique formula to convert percentage to dBm.

horray for standards

That is the one unifying principle that all geeks share.. Standards.

OT- joined a Geeks only social site ... Geeks.Pirrillio.net ( think I got that right.
Used a screen cap of google earth showing Vistumbler output as my profile pic. Thought I could pique some interest. It worked.

Somone hit me with a friend request and asked about the pic and what was used to generate it. I plugged the daylights out of Vistumbler and also noticed that their profile listed them as residing in MA as well. Don't ask what town... My short term memory seems to run a 12hr refresh rate LOL.