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Geolocation in Metro App - long delay experienced in Release Preview

    Question

  • I'm playing with Geolocation  CPP sample project on Win8 RP(8400).
    When I start tracking, the status will remain 'Initializing' for about 7 seconds before 'Ready'.
    After I stopped tracking, and restart tracking again, another 7 seconds before I could see the updated location data.
    Back in Win8 CP (8250), the experience is different, although the first access may take some time, the consequent re-tracking require little delay (about 1 sec).
    P.S. the one-time API GetGeopositionAsync() also has long delay, while in the past, we only wait several seconds after the first access to get data, following calls response very fast. 

    So I want to know what changes took place in the upgrade? -- Is there any documented issue about this?
    How to work around? -- I think none would like to suffer delay after each call.

    Tuesday, June 12, 2012 6:15 AM

Answers

All replies

  • Tuesday, June 12, 2012 6:20 AM
  • I think it depends on device. GPS will take a long time to find the sign, even will not find the sign.

    NEU_ShieldEdge

    Wednesday, June 13, 2012 3:13 AM
  • Hi Luke, if I use the WiFi based Windows Location Provider, the response is fast indeed.
    But when I switch to GPS device, the response is slow enough, even when I use GPS simulator that will populate data at high frequency.
    What I'm curious is the difference of Geolocation APIs on different OS version. I do expect faster response after the GPS signal becomes stable...
    Wednesday, June 13, 2012 5:48 AM
  • Would anyone give some hint? This is also long delay :P
    Tuesday, June 19, 2012 3:05 AM
  • Moved to the devices forum. Eric is looking into this.

    From what I'm reading, this is only with GPS and not specific to any particular device, correct?


    David Lamb

    Tuesday, June 19, 2012 5:12 PM
    Moderator
  • Hi Luke, if I use the WiFi based Windows Location Provider, the response is fast indeed.
    But when I switch to GPS device, the response is slow enough, even when I use GPS simulator that will populate data at high frequency.
    What I'm curious is the difference of Geolocation APIs on different OS version. I do expect faster response after the GPS signal becomes stable...

    Which GPS device are you using and which simulator are you using?

    Best Wishes - Eric

    Wednesday, June 20, 2012 12:40 AM
    Moderator
  • Yes David, this is related with GPS. And to avoid my own bug, I used the sample app just to get the same result.
    Wednesday, June 20, 2012 12:42 AM
  • I mainly use GPSDirect and choose its simulation.
    http://www.turboirc.com/gps7/
    Wednesday, June 20, 2012 12:44 AM
  • To avoid other location provider's intervention, I also disabled the Microsoft Visual Studio Location Simulator Sensor in control panel.
    GPSDirect will emit location info frequently ...

    Wednesday, June 20, 2012 12:54 AM
  • Could you try it with the Ublox external USB GPS available with Microsoft Streets
    and Trips 2011 w/GPS?  Do you have this one.  If so could you install this with it:  http://www.u-blox.com/en/evaluation-tools-a-software/u-center/u-tray-gps-for-windows-7.html
    Wednesday, June 20, 2012 6:27 AM
    Moderator
  • Thanks a lot Hanson.
    Read the link and got 2 questions:

    1. Seems I need a USB-connected u-blox GPS receiver? (in my device GPs module is supposed to be built-in)
    2. The receiver communicates to u-tray via the Windows 7 Sensor and Location platform.
    But the sample is for Win8, and I'm expecting the sample to work properly with less delay.

    Wednesday, June 20, 2012 6:43 AM
  • And after I installed u-tray on my win8 machine, cannot start it...
    Wednesday, June 20, 2012 8:52 AM
  • Only if you happen to have a streets and trips GPS device.  No need to go get one.  If you have one it would be worth testing.  Are you unable to start Windows or the tray app?
    Wednesday, June 20, 2012 2:56 PM
    Moderator
  • Yes I cannot start the tray app after installation, even in the task manager i could not see the process.
    Wednesday, June 20, 2012 4:55 PM
  • Is this with the GPS unit from streets and trips installed?
    Wednesday, June 20, 2012 10:56 PM
    Moderator
  • The tray-app alone.
    Thursday, June 21, 2012 1:16 AM
  • You likely need the hardware as well.  I will continue to look into this for you.

    Best Wishes - Eric

    Thursday, June 21, 2012 4:33 AM
    Moderator
  • Hello,

    If GPS is needed then desired accuracy (http://msdn.microsoft.com/en-us/library/windows/apps/br225603.aspx) should be set to high.

    This is a good resource on using Geolocation:  http://msdn.microsoft.com/en-us/library/windows/apps/hh465148.aspx

    Set the DesiredAccuracy property

    To help conserve power, your app should set the DesiredAccuracy property, to indicate to the location platform whether or not your app needs high accuracy data. If no apps require high-accuracy data, the system can save power by not turning on GPS providers.

    Note  Set Desired accuracy to HIGH if GPS data is important for your app.


    This posting is provided “AS IS” with no warranties, and confers no rights.

    Thursday, June 28, 2012 5:00 PM
  • HI Hanson & Mark,
    this really works, response time shortens to 3s if I call GetGeopostionAsync() or subscribe to PositionChanged again.
    Guess that's my desired result, great thanks to you all! :)

    Reason why I had shorter delay in previous version might be the default DesiredAccuracy is HIGH but currently DEFAULT in 8400?
    Friday, June 29, 2012 1:27 AM
  • Great news!  Yes this is very possibly the reason.

    Best Wishes - Eric

    Friday, June 29, 2012 1:31 AM
    Moderator