最近在调试GPS北斗双模，目前已经都调试通了，下面就来说一下涉及的几个关键词。
GPS: GPS是英文Global Positioning System（全球定位系统）的简称。GPS起始于1958年美国军方的一个项目，1964年投入使用。20世纪70年代，美国陆海空三军联合研制了新一代卫星定位系统GPS 。主要目的是为陆海空三大领域提供实时、全天候和全球性的导航服务，并用于情报搜集、核爆监测和应急通讯等一些军事目的，经过20余年的研究实验，耗资300亿美元，到1994年，全球覆盖率高达98%的24颗GPS卫星星座己布设完成。
NMEA协议：做导航定位方面的通讯协议，一般都指的NMEA0813，它是NMEA协议的一种，NMEA是为了在不同的全球定位系统导航设备中建立统一的海事无线电技术委员会（BTCM）标准，是国际海洋电子协会（National Marine Electronics Association，NMEA）定义的接收机输出信息标准。它有几个关键的标准语句如下：
$GPGGA (GGA2Global Positioning System Fix Data)
$GPGLL (Geographic Position – Latitude/Longitude)
$GPGSA (GPS DOP and active satellites)
$GPGSV (Satellites in view)
$GPRMC (Recommended Minimum Navigation Information)
$GPVTG (Track made good and Ground speed)
北斗：北斗即北斗卫星导航系统﹝BeiDou Navigation Satellite System，英文缩写BDS﹞是中国正在实施的自主发展、独立运行的全球卫星导航系统。系统建设目标是：建成独立自主、开放兼容、技术先进、稳定可靠的覆盖全球的北斗卫星导航系统，促进卫星导航产业链形成，形成完善的国家卫星导航应用产业支撑、推广和保障体系，推动卫星导航在国民经济社会各行业的广泛应用。
以上资料都是来至于网上资料，稍微整理了一下。也稍稍打下也基础。
GPS北斗模块输出的都是符合NMEA0183协议的语句，这些语句的格式都是确定了的，这样大家接收到以后才能解析好，下面贴一段双模输出的log看看，有个初步印象：
$GNGGA,033318.000,2234.6973,N,11355.2708,E,1,12,0.8,55.57,M,-2.7,M,0.0,0000,1.4*72 $GNGLL,2234.6973,N,11355.2708,E,033318.000,A,0*3E $GPGSA,A,3,05,02,13,10,17,12,06,25,09,26,,,1.5,0.8,1.4,0.8*3C $BDGSA,A,3,03,04,,,,,,,,,,,1.5,0.8,1.4,0.8*27 $GPGSV,3,1,10,10,56,021,42,05,55,255,44,02,46,340,42,06,41,043,39*75 $GPGSV,3,2,10,13,40,140,42,12,34,276,41,17,33,131,41,09,23,054,34*70 $GPGSV,3,3,10,26,13,184,33,25,11,309,35*78 $BDGSV,2,1,06,08,73,098,35,03,62,188,35,09,59,241,25,01,49,130,22*6D $BDGSV,2,2,06,04,32,111,34,10,03,198,34*68 $GNRMC,033318.000,A,2234.6973,N,11355.2708,E,0.000,50.711,281114,,,A*45 $RUANT,2*42 $GNGGA,033319.000,2234.6973,N,11355.2708,E,1,13,0.8,55.57,M,-2.7,M,0.0,0000,1.4*72 $GNGLL,2234.6973,N,11355.2708,E,033319.000,A,0*3F $GPGSA,A,3,05,13,02,10,17,12,06,25,09,26,,,1.5,0.8,1.4,0.8*3C $BDGSA,A,3,03,04,01,,,,,,,,,,1.5,0.8,1.4,0.8*26 $GPGSV,3,1,10,10,56,021,41,05,55,255,44,02,46,340,41,06,41,043,39*75 $GPGSV,3,2,10,13,40,140,41,12,34,276,41,17,33,131,41,09,23,054,34*73 $GPGSV,3,3,10,26,13,184,33,25,11,309,35*78 $BDGSV,1,1,04,03,62,188,34,01,49,130,22,04,32,111,33,10,03,198,34*62 $GNRMC,033319.000,A,2234.6973,N,11355.2708,E,0.000,50.711,281114,,,A*44 $RUANT,2*42 $GNGGA,033320.000,2234.6973,N,11355.2708,E,1,13,0.8,55.57,M,-2.7,M,0.0,0000,1.4*78 $GNGLL,2234.6973,N,11355.2708,E,033320.000,A,0*35 $GPGSA,A,3,05,13,02,10,17,12,06,25,09,26,,,1.5,0.8,1.4,0.8*3C $BDGSA,A,3,03,04,01,,,,,,,,,,1.5,0.8,1.4,0.8*26 $GPGSV,3,1,10,10,56,021,41,05,55,255,44,02,46,340,41,06,41,043,39*75 $GPGSV,3,2,10,13,40,140,41,12,34,276,41,17,33,131,41,09,23,054,34*73 $GPGSV,3,3,10,26,13,184,33,25,11,309,35*78 $BDGSV,1,1,04,03,62,188,34,01,49,130,23,04,32,111,32,10,03,198,33*65 $GNRMC,033320.000,A,2234.6973,N,11355.2708,E,0.000,50.711,281114,,,A*4E $RUANT,2*42 $GNGGA,033321.000,2234.6973,N,11355.2708,E,1,13,0.7,55.57,M,-2.7,M,0.0,0000,1.3*71 $GNGLL,2234.6973,N,11355.2708,E,033321.000,A,0*34 $GPGSA,A,3,05,13,02,10,17,12,06,25,09,26,,,1.5,0.7,1.3,0.8*34 $BDGSA,A,3,01,03,04,,,,,,,,,,1.5,0.7,1.3,0.8*2E $GPGSV,3,1,10,10,56,021,41,05,55,255,44,02,46,340,41,06,41,043,39*75 $GPGSV,3,2,10,13,40,140,41,12,34,276,41,17,33,131,41,09,23,054,34*73 $GPGSV,3,3,10,26,13,184,34,25,11,309,35*7F $BDGSV,1,1,04,03,62,188,39,01,49,130,33,04,32,111,37,10,03,198,33*6C $GNRMC,033321.000,A,2234.6973,N,11355.2708,E,0.000,50.711,281114,,,A*4F $RUANT,2*42 $GNGGA,033322.000,2234.6973,N,11355.2708,E,1,13,0.7,55.57,M,-2.7,M,0.0,0000,1.3*72 $GNGLL,2234.6973,N,11355.2708,E,033322.000,A,0*37 $GPGSA,A,3,05,02,13,10,17,12,06,25,09,26,,,1.5,0.7,1.3,0.8*34 $BDGSA,A,3,01,03,04,,,,,,,,,,1.5,0.7,1.3,0.8*2E $GPGSV,3,1,10,10,56,021,41,05,55,255,44,02,46,340,42,06,41,043,39*76 $GPGSV,3,2,10,13,40,140,42,12,34,276,41,17,33,131,41,09,23,054,34*70 $GPGSV,3,3,10,26,13,184,34,25,11,309,35*7F $BDGSV,1,1,04,03,62,188,39,01,49,130,32,04,32,111,38,10,03,198,34*65 $GNRMC,033322.000,A,2234.6973,N,11355.2708,E,0.000,50.711,281114,,,A*4C $RUANT,2*42 $GNGGA,033323.000,2234.6973,N,11355.2708,E,1,13,0.7,55.57,M,-2.7,M,0.0,0000,1.3*73 $GNGLL,2234.6973,N,11355.2708,E,033323.000,A,0*36 $GPGSA,A,3,05,02,13,10,17,12,06,26,25,09,,,1.5,0.7,1.3,0.8*34 $BDGSA,A,3,01,03,04,,,,,,,,,,1.5,0.7,1.3,0.8*2E $GPGSV,3,1,10,10,56,021,41,05,55,255,44,02,46,340,42,06,41,043,39*76 $GPGSV,3,2,10,13,40,140,42,12,34,276,41,17,33,131,41,09,23,054,34*70 $GPGSV,3,3,10,26,13,184,35,25,11,309,35*7E $BDGSV,1,1,04,03,62,188,39,01,49,130,31,04,32,111,37,10,03,198,34*69 $GNRMC,033323.000,A,2234.6973,N,11355.2708,E,0.000,50.711,281114,,,A*4D $RUANT,2*42 $GNGGA,033324.000,2234.6973,N,11355.2708,E,1,12,0.8,55.57,M,-2.7,M,0.0,0000,1.4*7D $GNGLL,2234.6973,N,11355.2708,E,033324.000,A,0*31 $GPGSA,A,3,05,02,13,10,12,17,06,26,25,09,,,1.5,0.8,1.4,0.8*3C $BDGSA,A,3,03,04,,,,,,,,,,,1.5,0.8,1.4,0.8*27 $GPGSV,3,1,10,10,56,021,42,05,55,255,44,02,46,340,42,06,41,043,39*75 $GPGSV,3,2,10,13,40,140,42,12,34,276,41,17,33,131,42,09,23,054,35*72 $GPGSV,3,3,10,26,13,184,36,25,11,309,35*7D $BDGSV,1,1,04,08,73,098,37,03,62,188,39,04,32,111,37,10,03,198,34*6C $GNRMC,033324.000,A,2234.6973,N,11355.2708,E,0.000,50.711,281114,,,A*4A $RUANT,2*42 $GNGGA,033325.000,2234.6973,N,11355.2708,E,1,12,0.8,55.57,M,-2.7,M,0.0,0000,1.4*7C $GNGLL,2234.6973,N,11355.2708,E,033325.000,A,0*30 $GPGSA,A,3,05,02,13,12,17,10,06,26,25,09,,,1.5,0.8,1.4,0.8*3C $BDGSA,A,3,03,04,,,,,,,,,,,1.5,0.8,1.4,0.8*27 $GPGSV,3,1,10,10,56,021,42,05,55,255,44,02,46,340,42,06,41,043,39*75 $GPGSV,3,2,10,13,40,140,42,12,34,276,42,17,33,131,42,09,23,054,35*71 $GPGSV,3,3,10,26,13,184,36,25,11,309,35*7D $BDGSV,2,1,05,08,73,098,38,03,62,188,39,09,59,241,41,04,32,111,38*6C $BDGSV,2,2,05,10,03,198,34*58 $GNRMC,033325.000,A,2234.6973,N,11355.2708,E,0.000,50.711,281114,,,A*4B $RUANT,2*42 $GNGGA,033326.000,2234.6973,N,11355.2708,E,1,12,0.8,55.57,M,-2.7,M,0.0,0000,1.4*7F $GNGLL,2234.6973,N,11355.2708,E,033326.000,A,0*33 $GPGSA,A,3,05,02,13,10,17,12,06,26,25,09,,,1.5,0.8,1.4,0.8*3C $BDGSA,A,3,03,04,,,,,,,,,,,1.5,0.8,1.4,0.8*27 $GPGSV,3,1,10,10,56,021,42,05,55,255,45,02,46,340,42,06,41,043,39*74 $GPGSV,3,2,10,13,40,140,42,12,34,276,42,17,33,131,42,09,23,054,35*71 $GPGSV,3,3,10,26,13,184,37,25,11,309,35*7C $BDGSV,2,1,06,03,62,188,40,09,59,241,40,01,49,130,41,04,32,111,38*6D $BDGSV,2,2,06,05,23,255,37,10,03,198,34*69 $GNRMC,033326.000,A,2234.6973,N,11355.2708,E,0.000,50.711,281114,,,A*48 $RUANT,2*42 $GNGGA,033327.000,2234.6973,N,11355.2708,E,1,14,0.7,55.57,M,-2.7,M,0.0,0000,1.3*70 $GNGLL,2234.6973,N,11355.2708,E,033327.000,A,0*32 $GPGSA,A,3,05,02,13,10,17,12,06,26,25,09,,,1.5,0.7,1.3,0.8*34 $BDGSA,A,3,01,03,04,05,,,,,,,,,1.5,0.7,1.3,0.8*2B $GPGSV,3,1,10,10,55,021,42,05,55,256,45,02,47,341,43,13,41,139,42*71 $GPGSV,3,2,10,06,41,044,39,12,34,275,42,17,32,132,42,09,22,053,35*7A $GPGSV,3,3,10,26,14,184,37,25,11,308,35*7A $BDGSV,2,1,06,03,62,188,41,01,49,130,41,02,34,247,35,04,32,111,39*69 $BDGSV,2,2,06,05,23,255,37,10,03,198,35*68 $GNRMC,033327.000,A,2234.6973,N,11355.2708,E,0.000,50.711,281114,,,A*49 $RUANT,2*42 $GNGGA,033328.000,2234.6973,N,11355.2708,E,1,14,0.7,55.57,M,-2.7,M,0.0,0000,1.3*7F $GNGLL,2234.6973,N,11355.2708,E,033328.000,A,0*3D $GPGSA,A,3,05,02,13,10,17,12,06,26,25,09,,,1.5,0.7,1.3,0.8*34 $BDGSA,A,3,01,03,04,05,,,,,,,,,1.5,0.7,1.3,0.8*2B $GPGSV,3,1,10,10,55,021,42,05,55,256,45,02,47,341,43,13,41,139,42*71 $GPGSV,3,2,10,06,41,044,39,12,34,275,42,17,32,132,42,09,22,053,35*7A $GPGSV,3,3,10,26,14,184,38,25,11,308,35*75 $BDGSV,2,1,06,03,62,188,40,01,49,130,41,02,34,247,36,04,32,111,38*6A $BDGSV,2,2,06,05,23,255,36,10,03,198,35*69 $GNRMC,033328.000,A,2234.6973,N,11355.2708,E,0.000,50.711,281114,,,A*46 $RUANT,2*42下一篇文章来解析这些log。