H's 手札

來源： Android模擬GPS數據生成kml和nmea文件 - 開發者在線 - www.builder.com.cn

在Android平台上開發可能沒有真機的時候，我們通過DDMS中載入KML或NMEA文件來模擬生產數據，使用方法參考 新版ADT插件讓Android開發更人性化 一文，最終這兩個文件加載到/data/misc/location/gps/nmea或/data/misc/location/gps/kml/

　　一、KML文件其實是一個XML文件，我們看下KML文件結構

　　<?xml version="1.0" encoding="UTF-8"?>

　　<kml xmlns="http://earth.google.com/kml/2.2">

　　<Document>

　　<name>1065 Brea Mall, Brea, CA 92821.kml</name>

　　<StyleMap id="default_copy0+nicon=http://maps.google.com/mapfiles/kml/pal3/icon60.png+hicon=http://maps.google.com/mapfiles/kml/pal3/icon52.png">

　　<Pair>

　　<key>normal</key>

　　<styleUrl>#default_copy0+icon=http://maps.google.com/mapfiles/kml/pal3/icon60.png</styleUrl>

　　</Pair>

　　<Pair>

　　<key>highlight</key>

　　<styleUrl>#default_copy0+icon=http://maps.google.com/mapfiles/kml/pal3/icon52.png</styleUrl>

　　</Pair>

　　</StyleMap>

　　<Style id="default_copy0+icon=http://maps.google.com/mapfiles/kml/pal3/icon52.png">

　　<IconStyle>

　　<scale>1.1</scale>

　　<Icon>

　　<href>http://maps.google.com/mapfiles/kml/pal3/icon52.png</href>

　　</Icon>

　　</IconStyle>

　　<LabelStyle>

　　<scale>1.1</scale>

　　</LabelStyle>

　　</Style>

　　<Style id="default_copy0+icon=http://maps.google.com/mapfiles/kml/pal3/icon60.png">

　　<IconStyle>

　　<Icon>

　　<href>http://maps.google.com/mapfiles/kml/pal3/icon60.png</href>

　　</Icon>

　　</IconStyle>

　　</Style>

　　<Placemark>

　　<name>1065 Brea Mall, Brea, CA 92821</name>

　　<address>1065 Brea Mall, Brea, CA 92821</address>

　　<LookAt>

　　<longitude>-117.883593</longitude>

　　<latitude>33.916991</latitude>

　　<altitude>0</altitude>

　　<range>1000</range>

　　<tilt>0</tilt>

　　<heading>0</heading>

　　</LookAt>

　　 <styleUrl>#default_copy0+nicon=http://maps.google.com/mapfiles/kml/pal3/icon60.png+hicon=http://maps.google.com/mapfiles/kml/pal3/icon52.png</styleUrl>

　　<Point>

　　<coordinates>-117.883593,33.916991,0</coordinates>

　　</Point>

　　</Placemark>

　　</Document>

　　</kml>

　　二、NMEA協議就是常規的GPS數據，通過串口直接獲取到的，如下

　　$GPRMC,003347.000,A,3725.3433,N,12205.7920,W,0.08,149.46,061007,,,D*70

　　$GPRMC,003348.000,A,3725.3433,N,12205.7921,W,0.05,142.51,061007,,,D*7E

　　$GPRMC,003349.000,A,3725.3432,N,12205.7921,W,0.08,159.56,061007,,,D*7E

　　$GPRMC,003350.000,A,3725.3432,N,12205.7921,W,0.06,151.59,061007,,,D*7F

　　$GPRMC,003351.000,A,3725.3432,N,12205.7921,W,0.20,120.57,061007,,,D*72

　　實例:

　　解析方法:

　　RMC = Recommended Minimum Specific GPS/TRANSIT Data

　　$GPRMC,hhmmss.ss,A,llll.ll,a,yyyyy.yy,a,x.x,x.x,ddmmyy,x.x,a*hh

　　1 = UTC(universal time, coordinated) of position fix

　　2 = Data status (A=good, V=navigation receiver warning)

　　3 = Current Latitude

　　4 = North/South in Latitude Hemisphere

　　5 = Current Longitude

　　6 = East/West in Longitude Hemisphere

　　7 = Speed over ground in knots

　　8 = (Direction of travel N:0°, E:90°, S:180°, W:270°)

　　9 = UT DateStamp

　　10 = Magnetic variation degrees (Easterly var. subtracts from true course)

　　11 = East/West

　　12 = Checksum

　　$GPRMC,003347.000,A,3725.3433,N,12205.7920,W,0.08,149.46,061007,,,D*70

　　Parts:

　　1: 003347.000 --> 0:33 am 47 seconds 0 milliseconds (UTC(universal time, coordinated) of position fix)

　　2: A --> Status is ok (Data status (A=good, V=navigation receiver warning))

　　3: 3725.3433 (North/South in Latitude Hemisphere)

　　4: N --> North (North/South)

　　5: 12205.7920 (Current Longitude)

　　6: W --> West (East/West in Longitude Hemisphere)

　　7: 0.08 --> 0.08 knots/second (Direction: North/West) (Speed over ground in knots)

　　8: 149.46 --> sth. like SouthEast (Direction of travel N:0°, E:90°, S:180°, W:270°)

　　9: 061007 --> 6th October, 2007 (UT(universal time) DateStamp)

　　10: <empty> (Magnetic variation degrees (Easterly var. subtracts from true course))