L/L stamping with APs.

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marco
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L/L stamping with APs.

Post by marco » Sat Feb 27, 2016 9:39 pm

I could probably look through the code and experiment further and all of those I will be doing but I need to ask the following as I am looking for an understanding sooner than later of the logic. Does VS apply what it understands to be the L/L to a VS sensed AP? When VS senses an AP, does VS associate its currently known L/L to that AP or does VS query the GPS device for the latest L/L and then subsequently associate to the AP?

Thanks for everyone's help.

Regards,

craig

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ACalcutt
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L/L stamping with APs.

Post by ACalcutt » Sat Feb 27, 2016 10:27 pm

That's a tough question...

The short answer is Vistumbler puts the access point where it had the highest signal and then highest number of gps satellites

The long answer is Vistumblers runs as a loop that *tries* to complete in the time set in (Settings --> Misc Settings--> Refresh loop time). The loop will take whatever time it needs and can run over the refresh loop time. If it completes early it waits the remaining time until the refresh loop time is reached.

In the loop it does the following, if the options are enabled
1.) Gets the current gps position from the wifidb or gps device (gps device is preferred). These gps values are inserted into the vistumbler db as a new GPS ID
2.) Scans current access points using the windows native wifi api or netsh (native wifi api is the default in the latest version). New access points get inserted with the current GPS ID. If the access point already exists it sets the gps to the current location if ap signal is higher, then if the number of gps satellites is higher. A history record is also created with AP ID, current GPS ID, Signal, RSSI, and Time. The ap listview and treeview are updated after this batch of aps is inserted into the database
3.) Draws the graphs, Speaks signal, MIDI, Camera triggers, AutoKML, other extras
4.) Handles window resizing
5.) Handles sorting, exiting and clearing
6.) Sleeps until 'refresh loop time' is reached, then goes back to step 1

In the code you will see the main loop under after the text "PROGRAM RUNNING LOOP". If you search vistumbler.au3 for that text, you will see the main loop right under that

arizonajon
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L/L stamping with APs.

Post by arizonajon » Sun Feb 28, 2016 1:52 pm

What Andrew said.

Vistumbler doesn't "know" where the AP is, Vistumbler only knows where the GPS connected to the PC running Vistumbler is. So all estimates of AP position are really where the GPS position is. A neat thing about WiFiDB (the database that processes the Vistumbler log files) is that it can graph using Google Earth the received signal strength as a function of position.

Here in Phoenix Cox Communications (the local cable internet service provider) has been hanging Wi-Fi APs all over town wherever they have aerial cable and there's some commercial/pedestrian traffic potential. The following two pix are for coxwifi B0:00:B4:61:30:A0 which is on the aerial coax just west of Scottsdale on the north side of Shea.

This shows the overall coverage from the AP. You can see that it's pretty significant, though pretty sketchy as well. The AP is hung from the aerial coax on the power poles along the north side of Shea Blvd. The coax is generally about 18-25' above the ground.
AP_coxwifi_shea_scottsdale.png
AP_coxwifi_shea_scottsdale.png (983.12 KiB) Viewed 1421 times
This is zoomed in and it's practical to see the buildings right around it and then go on the street and find it on the coax. Here, they use Cisco boxes with 3 antennas on the bottom of the box. Same form as a large full-size facial tissue box, just a bit bigger.
AP_coxwifi_shea_scottsdale_zoomed.png
AP_coxwifi_shea_scottsdale_zoomed.png (1.18 MiB) Viewed 1421 times
Of course, for an AP inside a building or residence, all you'd know is that the strongest signal is at the location indicated. That may be the closest approach to the AP but it could also be the lowest loss RF path to the AP, so estimating takes a bit of skill.

Cheers - Jon N7UV

marco
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L/L stamping with APs.

Post by marco » Sat Mar 05, 2016 9:52 pm

Thank you both, Andrew and Jon! Thank you for taking the time to type it all up. Need to chew on it but will let you know how the project goes.

craig

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