public static string FixDimensionString(FixDimension value)
{
switch (value)
{
case FixDimension.None:
return("None");
case FixDimension.Clock_1D:
return("1D Clock");
case FixDimension.Position_2D:
return("2D Position");
case FixDimension.Position_3D:
return("3D Position");
case FixDimension.OverDetermined:
return("OverDet Clock");
default:
return("Unknown");
}
}
/// <summary>
/// This packet provides a list of satellites used for position or time-only fixes by the GPS
/// receiver. The packet also provides the dilution of precision values PDOP, HDOP, VDOP and TDOP
/// of that set and provides the current mode (automatic or manual, 3-D or 2-D, Over-Determined Clock
/// mode, etc.). This packet has variable length equal to (17 + nsvs) where "nsvs" is the
/// number of satellites used in the solution. If an SV is rejected for use by the T-RAIM
/// algorithm then the SV PRN value will be negative.
///
/// PDOP = positional DOP
/// HDOP = horizontal DOP
/// VDOP = vertical DOP
/// TDOP = temporal DOP
///
/// Note: The GPS receiver sends this packet in response to packet 0x24 or automatically.
/// </summary>
private void sat_list(TsipPacket tp)
{
byte mode, count, dimension;
dimension = mode = count = tp.GetNextByte();
dimension &= 0x07; // fix dimension is in first 3 bits
mode &= 0x08; // mode is in bit 3
mode >>= 3;
count >>= 4; // tracked sat count in upper 4 bits
//Debug.Print(":0x6D (Satellite List count = {0})", count);
positional_dop = Helpers.FloatToFixPrecision(tp.GetNextSingle());
horizontal_dop = Helpers.FloatToFixPrecision(tp.GetNextSingle());
vertical_dop = Helpers.FloatToFixPrecision(tp.GetNextSingle());
temporal_dop = Helpers.FloatToFixPrecision(tp.GetNextSingle());
fix_dimension = Helpers.ByteToFixDimension(dimension);
fix_mode = Helpers.ByteToFixMode(mode);
for (int i = 0; i < 32; i++) // clear current tracking flags
Satellites[i].UsedInFix = false;
for (int i = 0; i < count; i++)
{
bool used = true;
byte prn = tp.GetNextByte();
if ((prn & 0x80) == 0x80) // satellite is tracked but is not used in fix
{
used = false;
prn &= 0x7F;
}
prn--;
if (prn > 31)
continue; // disregard bogus data
Satellites[prn].Tracked = true;
Satellites[prn].UsedInFix = used;
}
}
