Influence of WiFi on GPS readings (200m error)
C R McClenaghan
chris at mcclenaghan.com
Mon Jul 21 16:54:56 CEST 2008
I'm not sure where the fault lies, but with tangogps, I seem to get a
scatter plot displayed for my position. Initially the fix seems
accurate, then it starts to wander, although I may not be. If I am
moving, the trial doesn't seem to follow the route I've taken. I think
it may be tangogps, but I thought I'd try using my garmin bluetooth in
a "side by side" kind of test to see whether it is tangogps or the gps
On Jul 21, 2008, at 12:02 AM, Russell Sears wrote:
> I've had this problem when the initial fix was obtained while I'm
> 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
>> Running TangoGPS. While WiFi is on (WEP encrypted. wpa_supplicant
>> powered ;)) I am having location error (never hit the right spot)
>> 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
>> a bias of 10m or so.
>> Therefore, the question: is that expected? ie that we can't rely on
>> 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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