Ticket #1981 (closed defect: wontfix)

Opened 9 years ago

Last modified 8 years ago

[GPS] is inaccurate / [Location] red spot sparkling by around location not exactly where we are.

Reported by: regina_kim Owned by: jeremy
Priority: normal Milestone: Om2008.9
Component: hardware Version:
Severity: normal Keywords:
Cc: testing@… Blocked By:
Blocking: Estimated Completion (week):
HasPatchForReview: no PatchReviewResult:
Reproducible: always

Description

Description : red spot sparkling by around location not exactly where we are.

step+current result :

  1. open location
  2. searching location where i am.
  3. red spot shining when fixed location --> but location is not correct

expected result :
it should be shining correct place where i am.

Attachments

nmea_drift.log (250.8 KB) - added by jeremy 9 years ago.
nmea_drift_rmc.log (33.5 KB) - added by jeremy 9 years ago.
drift nmea log grepped

Change History

comment:1 Changed 9 years ago by jeremy

  • Owner changed from openmoko-devel to jeremy
  • Status changed from new to accepted

comment:2 Changed 9 years ago by jeremy

This should be the issue of hardware or firmware of ublox chip, This issue needs to go to contact with vendor. Nmea log will be attached later.

comment:3 Changed 9 years ago by will

  • Summary changed from [Location] red spot sparkling by around location not exactly where we are. to [GPS] is inaccurate / [Location] red spot sparkling by around location not exactly where we are.

Thanks to some insight from Marek:

GPS is known to be inaccurate for several reasons which are
explained in detail on the web. I collected a few links that should serve as
a starting point:

Easy to understand summary:
http://en.wikipedia.org/wiki/Dilution_of_precision_(GPS)

A rather scientific page with lots of examples:
http://www.earthmeasurement.ca/GPS_accuracy.html

Another summary:
http://www.sailtrain.co.uk/gps/limitations.htm

comment:4 Changed 9 years ago by jeremy

Hi, as I observed, the gps chip seems to get a fix as possible as based on the signals it received. I tried to hold at the same position under good environment to get a fix, it started with a non-precise but close fix then quickly drift to precise position. Then I walked toward to and along building edges with not really good environment, it happened to lost the fix and got a worse non-precise fix soon again, back and forth. The logs are attached.
It indeed is affected based on degrees of Surrounding conditions, but that's chip's behavior. We may ask vendor and compare with other products to distinguish it's an issue or not.

Changed 9 years ago by jeremy

Changed 9 years ago by jeremy

drift nmea log grepped

comment:5 Changed 8 years ago by john_lee

  • Status changed from accepted to closed
  • Component changed from unknown to hardware
  • HasPatchForReview unset
  • Resolution set to wontfix

i don't think there is anything we can do. even if we can find a better chip, gta02 is already shipped.

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