1- package com .hoho .android .usbserial .examples ;
1+ package com .mikey0000 .android .usbserial .examples ;
22
33/**
44 * Created by michaelarthur on 2/09/15.
55 */
66
77import android .location .Location ;
88import android .os .SystemClock ;
9- import android .util .Log ;
109
11- import java .lang .reflect .InvocationTargetException ;
12- import java .lang .reflect .Method ;
1310import java .util .HashMap ;
1411import java .util .Map ;
1512
1613
1714public class NMEAParser {
1815
19- // fucking java interfaces
16+ // java interfaces
2017 interface SentenceParser {
2118 public boolean parse (String [] tokens , GPSPosition position );
2219 }
@@ -30,8 +27,6 @@ static float Latitude2Decimal(String lat, String NS) {
3027 med = -med ;
3128 }
3229 return med ;
33-
34-
3530 }
3631
3732 static float Longitude2Decimal (String lon , String WE ) {
@@ -41,7 +36,6 @@ static float Longitude2Decimal(String lon, String WE) {
4136 med = -med ;
4237 }
4338 return med ;
44-
4539 }
4640
4741 // parsers
@@ -51,6 +45,8 @@ public boolean parse(String[] tokens, GPSPosition position) {
5145 position .lat = Latitude2Decimal (tokens [2 ], tokens [3 ]);
5246 position .lon = Longitude2Decimal (tokens [4 ], tokens [5 ]);
5347 position .quality = Integer .parseInt (tokens [6 ]);
48+ position .numberOfSatellites = Integer .parseInt (tokens [7 ]);
49+ position .hdop = Float .parseFloat (tokens [8 ]);
5450 position .altitude = Float .parseFloat (tokens [9 ]);
5551 return true ;
5652 }
@@ -94,32 +90,52 @@ public class GPSPosition {
9490 public float time = 0.0f ;
9591 public float lat = 0.0f ;
9692 public float lon = 0.0f ;
97- public boolean fixed = false ;
9893 public int quality = 0 ;
9994 public float dir = 0.0f ;
10095 public float altitude = 0.0f ;
10196 public float velocity = 0.0f ;
97+ public int numberOfSatellites = 0 ;
98+ // See: https://en.wikipedia.org/wiki/Dilution_of_precision_(navigation)
99+ public float hdop = 0.0f ;
100+
101+ public boolean fixed = false ;
102102
103103 public void updatefix () {
104104 fixed = quality > 0 ;
105105 }
106106
107107 public String toString () {
108- return String .format ("POSITION: lat: %f, lon: %f, time: %f, Q: %d, dir: %f, alt: %f, vel: %f" , lat , lon , time , quality , dir , altitude , velocity );
108+ return String .format (
109+ "POSITION: lat: %f, lon: %f, time: %f, Q: %d, hdop: %f, dir: %f, alt: %f, vel: %f, # of sat: %d, fixed: %b" ,
110+ lat , lon , time , quality , hdop , dir , altitude , velocity , numberOfSatellites , fixed
111+ );
109112 }
110113 }
111114
112115 GPSPosition position = new GPSPosition ();
113116
114117 private static final Map <String , SentenceParser > sentenceParsers = new HashMap <String , SentenceParser >();
115118
119+ /**
120+ * Maps a NMEA quality identifier to the best possible accuracy value (in meters)
121+ */
122+ protected static final Map <Integer ,Float > qualityAccuracy = new HashMap <Integer , Float >();
123+
116124 public NMEAParser () {
117125 sentenceParsers .put ("GPGGA" , new GPGGA ());
118126 sentenceParsers .put ("GPGGL" , new GPGGL ());
119127 sentenceParsers .put ("GPRMC" , new GPRMC ());
120128 sentenceParsers .put ("GPRMZ" , new GPRMZ ());
121129 //only really good GPS devices have this sentence but ...
122- sentenceParsers .put ("GPVTG" , new GPVTG ());
130+ //sentenceParsers.put("GPVTG", new GPVTG());
131+
132+ // concrete accuracy values (in meters) per NMEA quality level
133+ // this is used to calculate the position accuracy in NMEAParser.calculateAccuracy
134+ qualityAccuracy .put ( 0 , 0.0f ); // invalid
135+ qualityAccuracy .put ( 1 , 2.0f ); // GPS 2d/3d
136+ qualityAccuracy .put ( 2 , 0.7f ); // DGNSS
137+ qualityAccuracy .put ( 4 , 0.04f ); // RTK fixed
138+ qualityAccuracy .put ( 5 , 0.04f ); // RTK fixed
123139 }
124140
125141 public GPSPosition parse (String line ) {
@@ -149,24 +165,28 @@ public GPSPosition parse(String line) {
149165 }
150166
151167 public Location location (String str ) {
152- Location localLocation ;
153- GPSPosition GPSPos = parse (str );
154-
155- if (!GPSPos .fixed ) {
156- GPSPos = null ;
157- return null ;
168+ Location localLocation = null ;
169+ parse ( str );
170+
171+ if ( position .quality > 0 ) { // quality 0 is an invalid entry
172+ localLocation = new Location ("gps" );
173+ localLocation .setLongitude (position .lon );
174+ localLocation .setLatitude (position .lat );
175+ localLocation .setAltitude (position .altitude );
176+ localLocation .setSpeed (position .velocity );
177+ localLocation .setBearing (position .dir );
178+ localLocation .setTime (System .currentTimeMillis ());
179+ localLocation .setElapsedRealtimeNanos (SystemClock .elapsedRealtimeNanos ());
180+ localLocation .setAccuracy (calculateAccuracy ());
181+
182+ position = new GPSPosition ();
158183 }
159184
160- localLocation = new Location ("gps" );
161- localLocation .setLongitude (GPSPos .lon );
162- localLocation .setLatitude (GPSPos .lat );
163- localLocation .setAltitude (GPSPos .altitude );
164- localLocation .setSpeed (GPSPos .velocity );
165- localLocation .setBearing (GPSPos .dir );
166- localLocation .setTime (System .currentTimeMillis ());
167- localLocation .setElapsedRealtimeNanos (SystemClock .elapsedRealtimeNanos ());
168- localLocation .setAccuracy (GPSPos .quality );
169-
170185 return localLocation ;
171186 }
187+
188+ protected float calculateAccuracy () {
189+
190+ return qualityAccuracy .get ( position .quality ) * position .hdop ;
191+ }
172192}
0 commit comments