Access Point GPS Coordinates

[kikilala]

Hi,

Found this great apps while searching for Wifi sniffer for vista. Been tinkering with it for few days and it works great. Good job to the developers

I'm trying to figure how does vistumbler calculate the GPS coordinates for the APs that it finds? Say I'm at location X and my GPS readings are lat A, long B. The only possible answer I can think off is Vistumbler uses the AP's signal strength measurement and translates that into distance d centered on my location X, but that will mean the AP can be anywhere on the circumference of radius d. I would assume you'll need at least 3 known locations to properly triangulate the actual AP position, no?

[ACalcutt]

Well the GPS position is read off of the gps unit, not based on access points. The Access point position is the location where the gps sees the most satellites (most accurate position) and where the AP has the highest signal.

For a good gps fix it is recommended to have at least 3 satellites

no triangulation of the APs yet....maybe someday

[kikilala]

Ok, let me rephrase your answer to see if I get this right.

The AP position is basically the GPS position with the highest signal strength value. Example: Say I'm at location X with GPS reading of lat a, long b. At that position, I measure the signal strength of AP 1 to be 50%. Then I move to another location Y with GPS reading of lat c, long d and the signal strength measurement of AP 1 is 80%. So AP 1 position reported by Vistumbler is actually location Y i.e. lat c, long d. Is my assumption correct?

Sorry if my question sounds trivial.

[ACalcutt]

yes, as long as the number of gps satellites isn't higher at lat a, long b

say for example

Code: Select all

-GPS Point 1
lat a, long b
Number of sat = 08
Signal = 50%

-GPS Point 2
lat c, long d
Number of sat = 07
Signal = 80%

GPS point 1 would be used because it has a better quality of position (higher number of satellites).

As long as the number of satellites stays equal or higher then AP signal is used...Say we add GPS Point 3

Code: Select all

-GPS Point 3
lat e, long f
Number of sat = 08
Signal = 79%

GPS Point 3 would be used because it has the highest Number of satellites(equal to GPS Point 1) and the higher signal