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c#.netwindows-phone-8gpsgps-time

Windows Phone, Can you get the real time from GPS?

Is it possible to get the real time, not system time (as this can be changed) from a GPS location request?

It seems like 

Geoposition.Coordinate.Timestamp

is the system time, see here: http://msdn.microsoft.com/en-us/library/windows/apps/windows.devices.geolocation.geocoordinate.aspx

Timestamp Read-only The system time at which the location was determined.

I know I could use NTP server but what if I don't have a data connection.

Thanks

Steve

I guess i just need a definitive answer as to whether it's possible to get the time directly from the satellite or not.

Solution

  • I'm blind.

    For future reference, you can in 8.1.

    http://msdn.microsoft.com/en-us/library/windows/apps/windows.devices.geolocation.geocoordinate.aspx

    see PositionSource

    PositionSourceTimestamp Read-only Gets the time at which the associated Geocoordinate position was calculated.

    http://blogs.msdn.com/b/thunbrynt/archive/2014/04/22/windows-phone-8-1-for-developers-geolocation-and-geofencing.aspx

    From the above link:

    Geolocation In windows phone 8.0 we had two namespaces with almost identical content, the old System.Device.Location and the new Windows.Devices.Geolocation. In 8.1 only Windows.Devices.Geolocation is left. If you want to update old apps using the System.Device.Location there are plenty of information on the internet. The 8.0 maps api used System.Device.Location.GeoCoordinate but 8.1 now uses Windows.Devices.Geolocation.Geopoint. More on that in my previous blog: Windows Phone 8.1 for Developers – Maps The only other changes in Windows.Devices.Geolocation are two additional classes and one extra property on Geocoordinate:

    • GeoboundingBox: Represents a rectangle that defines a geographic area. Replaces the LocationRectangle used in the 8.0 map api

    • Geopath: Represents an ordered series of geographic points and is used for example when you create a MapPolygon.

    • Geocoordinate.PositionSourceTimestamp: Gets the time at which the associated Geocoordinate position was calculated, and may be completely unrelated to the system time on the device. E.g. if the position is obtained from GPS, the timestamp would be obtained from the satellites.

    The final bullet point is the useful one

    Thanks

    Steve