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PositionSource - doesn't use GPS RRS feed

  • Question

  • In my app I'm accessing the Geoposition data from PositionChanged event handler.

    Despite the Geolocater having the DesiredAccuracy set to High and the DesiredAccuracyInMeters set to 25, the store app never uses the GPS sensor built in to the device.
    If the value for Geoposition.Coordinate.Accuracy is above my desired accuracy should it not be initalizing the GPS sensor?

    So far I've seen it report WiFi, Cellular and IPAddress as the PositionSource.
    http://msdn.microsoft.com/en-us/library/windows/apps/windows.devices.geolocation.positionsource.aspx

    The location reported by WiFi and Cellular can often be sufficiently accurate but we're also experiencing instances where the position will be (consistently) reported as one of two locations far from the devices actual physical location.
    Our suspicion is that those positions are associated with specific IP addresses that may be reported due to firewall/proxy/direct access routing of the device's wireless connectivity options.

    Location is obviously enabled in the capabilities and the user permissions.

    I've confirmed the GPS sensor in the device is working via an OEM win32 app which the device ships with. This has been tested in good open space and in a vehicle with a powered GPS antenna.

    For what it's worth, enumerating the DeviceInformationCollection for DeviceClass.Location reports one device/sensor.
    I have not been able to determine whether that is the GPS sensor though.
    http://msdn.microsoft.com/en-US/library/windows/apps/windows.devices.enumeration.deviceclass

    When you disable wireless connections the PositionStatus returns "NoData", rather than "NotAvailable" which hints at the code still having access to an alternative location source.
    http://msdn.microsoft.com/en-us/library/windows/apps/windows.devices.geolocation.positionstatus.aspx
    Is there a way to check specifically for a GPS sensor within a Windows Store app?
    Any ideas why my app may not be causing the GPS sensor to initialize?

    Thanks in advance of your kind response.

    UPDATE: I've downloaded a couple of "sensor" data apps from the Windows Store, they show the same symptom.
    Although they're not displaying the Geoposition.Coordinate.PositionSource property in their UI I'm pretty confident that the value is null when the wireless networks are disabled. :(

    Anyone have a Win8 device with a GPS sensor they'd mind giving it a test on please?

    • Edited by RD8388 Friday, November 29, 2013 4:29 PM
    Thursday, November 28, 2013 3:16 PM

Answers

All replies

  • Hi,

    We will look into this.

    Thanks,

    Sagar

    Monday, December 2, 2013 4:11 PM
  • What GPS device are you using? Is it built in or external?

    Since you get the same behaviour in all apps it probably isn't an app issue but a system configuration or driver issue.

    The desktop app test isn't comprehensive since desktop apps can talk to different devices than Windows Store apps.

    --Rob

    Monday, December 2, 2013 4:22 PM
    Moderator
  • What GPS device are you using? Is it built in or external?

    Since you get the same behaviour in all apps it probably isn't an app issue but a system configuration or driver issue.

    The desktop app test isn't comprehensive since desktop apps can talk to different devices than Windows Store apps.

    --Rob

    It's a built in GPS sensor.
    The desktop application talks to the sensor via COM3 port.

    Monday, December 2, 2013 4:27 PM
  • Hi,

    We will look into this.

    Thanks,

    Sagar

    Thank you.
    We're contacting the hardware device supplier about the issue too.
    Monday, December 2, 2013 4:28 PM
  • The COM port is not sufficient.  There must be a sensor driver for this to work with Windows Store apps.  See this new blog! 

     http://aka.ms/Qcdza5


    Jeff Sanders (MSFT)

    @jsandersrocks - Windows Store Developer Solutions @WSDevSol
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    Tuesday, December 3, 2013 7:20 PM
    Moderator
  • Thanks Jeff.
    We're contacting the hardware manufacturer in the hope they can provide/suggest a suitable GNSS Sensor Driver.
    Wednesday, December 4, 2013 11:36 AM