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package nmea
const (
// TypeGSA type for GSA sentences
TypeGSA = "GSA"
// Auto - Field 1, auto or manual fix.
Auto = "A"
// Manual - Field 1, auto or manual fix.
Manual = "M"
// FixNone - Field 2, fix type.
FixNone = "1"
// Fix2D - Field 2, fix type.
Fix2D = "2"
// Fix3D - Field 2, fix type.
Fix3D = "3"
)
// GSA represents overview satellite data.
// http://aprs.gids.nl/nmea/#gsa
// https://gpsd.gitlab.io/gpsd/NMEA.html#_gsa_gps_dop_and_active_satellites
//
// Format: $--GSA,a,a,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x.x,x.x,x.x*hh<CR><LF>
// Format (NMEA 4.1+): $--GSA,a,a,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x.x,x.x,x.x,x*hh<CR><LF>
// Example: $GNGSA,A,3,80,71,73,79,69,,,,,,,,1.83,1.09,1.47*17
// Example (NMEA 4.1+): $GNGSA,A,3,13,12,22,19,08,21,,,,,,,1.05,0.64,0.83,4*0B
type GSA struct {
BaseSentence
Mode string // The selection mode.
FixType string // The fix type.
SV []string // List of satellite PRNs used for this fix.
PDOP float64 // Dilution of precision.
HDOP float64 // Horizontal dilution of precision.
VDOP float64 // Vertical dilution of precision.
// SystemID is (GNSS) System ID (NMEA 4.1+)
// 1 - GPS
// 2 - GLONASS
// 3 - Galileo
// 4 - BeiDou
// 5 - QZSS
// 6 - NavID (IRNSS)
SystemID int64
}
// newGSA parses the GSA sentence into this struct.
func newGSA(s BaseSentence) (Sentence, error) {
p := NewParser(s)
p.AssertType(TypeGSA)
m := GSA{
BaseSentence: s,
Mode: p.EnumString(0, "selection mode", Auto, Manual),
FixType: p.EnumString(1, "fix type", FixNone, Fix2D, Fix3D),
}
// Satellites in view.
for i := 2; i < 14; i++ {
if v := p.String(i, "satellite in view"); v != "" {
m.SV = append(m.SV, v)
}
}
// Dilution of precision.
m.PDOP = p.Float64(14, "pdop")
m.HDOP = p.Float64(15, "hdop")
m.VDOP = p.Float64(16, "vdop")
if len(p.Fields) > 17 {
m.SystemID = p.Int64(17, "system ID")
}
return m, p.Err()
}
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