How to calculate accuracy of latitude/longitude

Question

I'm updating a Windows Mobile application to capture location information using the built-in GPS hardware. The Microsoft API provides a method GPSGetPosition that returns the following struct (ref:GPS_POSITION):

typedef struct _GPS_POSITION {
    DWORD dwVersion;
    DWORD dwSize;
    DWORD dwValidFields;
    DWORD dwFlags;
    SYSTEMTIME stUTCTime;
    double dblLatitude;
    double dblLongitude;
    float  flSpeed;
    float  flHeading;
    double dblMagneticVariation;
    float  flAltitudeWRTSeaLevel;
    float  flAltitudeWRTEllipsoid;
    GPS_FIX_QUALITY     FixQuality;
    GPS_FIX_TYPE        FixType;
    GPS_FIX_SELECTION   SelectionType;
    float flPositionDilutionOfPrecision;
    float flHorizontalDilutionOfPrecision;
    float flVerticalDilutionOfPrecision;
    DWORD dwSatelliteCount;
    DWORD rgdwSatellitesUsedPRNs[GPS_MAX_SATELLITES];
    DWORD dwSatellitesInView;
    DWORD rgdwSatellitesInViewPRNs[GPS_MAX_SATELLITES];
    DWORD rgdwSatellitesInViewElevation[GPS_MAX_SATELLITES];
    DWORD rgdwSatellitesInViewAzimuth[GPS_MAX_SATELLITES];
    DWORD rgdwSatellitesInViewSignalToNoiseRatio[GPS_MAX_SATELLITES];
} GPS_POSITION, *PGPS_POSITION;

So I can determine the latitude and longitude but I would like to be able to calculate the accuracy of the result. The application runs on a Trimble Juno and the GPS Controller application on the device provides an accuracy value in metres. Is this something I can determine from the values in the struct or is this something specific to the hardware that would require a native function call? Is the accuracy value based on heuristics or is it a common calculation across different hardware?

Answer 1

Your dilution of precision is a representation of accuracy, however, it's not in meters. Have you seen this page with descriptions of each property of your struct?

Here is an explanation of the DOP scale and how it's calculated from actual measurements.