Influence of WiFi on GPS readings (200m error)

Russell Sears sears at
Mon Jul 21 09:02:41 CEST 2008

I've had this problem when the initial fix was obtained while I'm inside 
a vehicle (such as a bus or car) or near a lot of metal.  Going to a 
complete stop, then moving a few times (in the car) seems to give the 
chipset a better chance to realize it's got a bogus fix.


Yaroslav Halchenko wrote:
> Hi All,
> Finally I got to play with FR. Flushed todays (0721) dev image and kernel.
> Running TangoGPS. While WiFi is on (WEP encrypted. wpa_supplicant
> powered ;)) I am having location error (never hit the right spot) around
> 200-400m with reported speed from 0.5 to 20 km/h (while I am siting
> steadily in 1 place).
> When I turn WiFi Off (just on my FR, without touching access point or a
> laptop from which I am writing) -- location moves to the right spot with
> a bias of 10m or so.
> Therefore, the question: is that expected? ie that we can't rely on GPS
> readings while WiFi is on?  Or from the other side: what is
> 'documented' precision in GPS readings while WiFi is enabled (and not
> actually very actively used, if used at all  since I guess TangoGPS
> already had those tiles from OSM downloaded).
> Or may be it is just my FR which behaves that way? Did anyone observe
> any similar behavior?

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