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canadiangal
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Graphs

Post by canadiangal » Mon Feb 22, 2016 9:53 pm

I am a little confused on what the two graphs are supposed to show. I know it is the signal strength, but what does the spike mean?
What is graph 2 supposed to be showing? I tried to find a tutorial, but I am not having any luck
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graph1.jpg
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arizonajon
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Graphs

Post by arizonajon » Mon Feb 22, 2016 10:40 pm

Hi there -

Graph 1 and Graph 2 both are showing "signal strength" of the selected AP. In the case of your screengrab, it appears that the selected AP was out of range of (or at least extremely weak) the computer running Vistumbler for almost all the time shown, except for two samples (at least it looks like two) where the received signal was -10 dBm or so. The sample rate is about 1 per second so it appears that the selected AP was detected only for two seconds, then it was gone.

I'm not sure how signal strength calculation is done, I think Andrew described it some time ago, Sadly, I think that Windows provides only a value from 0 to 100%, and that it's not a real RSSI value. I read somewhere about the netsh command that the assumption is that 0% is -100 dBm, and 100% is -50 dBm, and that the other values are linearly interpolated. That really doesn't work well in real life since if one is within 10-20 ft line-of-sight of a typical AP, the RSSI will be generally much stronger than -50 dBm.

Cheers - Jon N7UV

canadiangal
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Graphs

Post by canadiangal » Mon Feb 22, 2016 11:04 pm

Sorry, I didn't realize that I had the same graph twice. I took a screen shot with graph 2, but was unclear about if the two graphs were supposed to show something different. Thank you Jon for the great information. Any tutorials out there?

arizonajon
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Post by arizonajon » Tue Feb 23, 2016 12:05 am

You're welcome.

To me, graph 1 and graph 2 just show the particular AP signal strength as either a bargraph or as a line. If there's some other difference or ability to configure them individually, I don't know. The way I use Vistumbler I never use the graphs, instead preferring the "minimal GUI" interface.

On tutorials, for Vistumbler? Just this group. Andrew and Phil are extremely helpful, and always cordial.

A core function of Vistumbler is the use of some variant of the "netsh wlan show" command, for which there are a lot of sources of info on the web.

Cheers - Jon N7UV

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Graphs

Post by ACalcutt » Tue Feb 23, 2016 5:52 pm

I just wanted to add one small correction on the signal strength. If you are using Native Wifi Mode (Options --> Use Native Wifi), which is the default since v10.3, then the RSSI value is what the card is reporting to the windows api. However, if you are using netsh mode, the value is estimated based on the signal % value netsh is reporting. Native Wifi mode enabled is the preferred way to run vistumbler and RSSI in this mode is a real value (though from what I've read, this value varies between wireless card manufactures and drivers)

Like Jon mentions, the main difference between the graphs is how it looks (baregraph vs linegraph). I prefer graph 2 (bargraph) because it can fit more points on the screen, but other than that it is the same information. The graphs are somewhat neglected in vistumbler since, like jon, we mainly use vistumbler for wireless mapping.

There isn't much in the way of documentation. We have a few sparse topics on our wiki ( https://github.com/RIEI/Vistumbler/wiki ), but it could really use some additions and updating. Theres a lot of information posted throughout the forum but feel free to ask any questions. we try to be an open place for discussion and help.

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