Application and development of GPS Beidou dual-mode technology--data analysis

In the previous article we introduced a few important concepts, then we will analyze the two-mode output log, before parsing we look at the significance of each important standard field. In the actual development of the author only used four of them, respectively, is GGA,GSA,GSV,RMC,GLL, of course, there are some other fields, feel some are repeating, according to the need to resolve the good. Here's a look at each:

$xxgga, (1) , (2), (3), (4), (5), (6), (7), (8), (9), M, (Ten), M, (one), (a) *hh (CR) (LF) The corresponding meanings are: (1) Location UTC time: 05:09 01 seconds (2) Latitude (format ddmm.mmmm : DD degrees, Mm.mmmm points), (3) N/S (north or south latitude): Latitude 39 degrees 31.4449 minutes, (4) Longitude (format dddmm.mmmm: DDD degree, mm.mmmm), (5) e/w (longitude or west longitude): East longitude 116 degrees 43.5123 minutes; (6 ) mass factor (0= no positioning, 1= real-time gps,2= differential GPS): 1= real-time GPs, (7) Number of satellites available (0~8): number of satellites available = 07, (8) horizontal accuracy factor (1.0~99.9), horizontal precision factor =1.4, (9) Antenna elevation (sea level, 　　-9999.9~99999.9, Unit: m); antenna elevation =76.2m); 　　(10) Height of the earth ellipsoid relative to sea level ( -999.9~9999.9, Unit: m): -7.0m; 　　(11) Differential GPS data age, real-time GPS No: none; 　　(12) Differential reference station number (0000~1023), real-time GPS without: none; * Sum check field; HH sum check number: (CR) (LF) carriage return, newline. 

 $XXGSA, <1>,<2>,<3>,<3>,<3>,<3>,<3>,<3>,<3>,<3>,<3>, <3>,<3>,<3>,<4>,<5>,<6>*hh<CR><LF><1> mode, m= Manual, a= automatic <2 > Positioning type, 1 = no positioning, 2=2d positioning, 3=3d location <3> PRN Code (pseudo-Random noise code), the satellite number being used to solve the position (01~32, the preceding 0 will also be transmitted). <4> Pdop positional accuracy factor (0.5~99.9) <5> Hdop horizontal precision factor (0.5~99.9) <6> Vdop Vertical precision factor (0.5~99.9) 

 $XXGSV,< 1>,<2>,<3>,<4>,<5>,<6>,<7>,... <4>,<5>,<6>,<7>*hh Total number of <CR><LF><1> GSV statements <2> number of GSV in this sentence <3> total number of visible satellites (00~12, 0 in front will also be transmitted) <4> The PRN code (pseudo-Random Noise Code) (01~32, the front 0 will also be transmitted) <5> satellite elevation (00~90度, the front 0 will also be transmitted) <6> satellite azimuth (000~359度, front 0 will also be transmitted) <7> signal-to-noise ratio (00~ 99dB, no tracking to the satellite when empty, the front of 0 will also be transmitted) Note:<4>,<5>,<6>,<7> information will be displayed in accordance with each satellite, each GSV statement can display up to 4 satellite information. Other satellite information will be output in the next sequence of NMEA0183 statements. 

 $XXRMC, <1>,<2>,<3>,<4>,<5>,<6>,<7>,<8>,<9>,<10>,<11 >,<12>*hh<CR><LF><1> UTC Time, HHMMSS (Hours/minute) format <2> positioning State, a= effective positioning, v= invalid location <3> The latitude ddmm.mmmm (in degrees) format (the front 0 will also be transmitted) <4> latitude hemisphere n (Northern hemisphere) or S (Southern hemisphere) <5> longitude dddmm.mmmm (in degrees) format (front 0 will also be transmitted) <6> Longitude hemisphere E (longitude) or W (west longitude) <7> Ground rate (000.0~999.9 section, front 0 will also be transmitted) <8> ground heading (000.0~359.9 degree, True North as reference, front 0 will also be transmitted) <9> UTC date, Ddmmyy (Sun Moon year) format <10> declination (000.0~180.0 degree, front 0 will also be transmitted) <11> declination direction, E (east) or W (West) <12> mode indication (only NMEA0183 3.00 version output, a= autonomous positioning, d= differential, e= estimation, n= data Invalid) 

$XXGLL,<1>,<2>,<3>,<4>,<5>,<6>,<7>*hh<cr><lf><1> The latitude ddmm.mmmm (in degrees) format (the front 0 will also be transmitted) <2> latitude hemisphere n (Northern hemisphere) or S (Southern hemisphere) <3> longitude dddmm.mmmm (in degrees) format (front 0 will also be transmitted) <4> Longitude hemisphere E (longitude) or W (West longitude) <5> UTC time, HHMMSS (hour/minute) format <6> positioning State, a= effective positioning, v= invalid location <7> mode indication (NMEA0183 3.00 version output only, a= autonomous positioning, D = differential, e= estimation, n= data Invalid)

All of these instructions are fixed, that is, the NMEA0183 protocol is well established. Above in Gga these beginning, the author used xx to blur the data head, is because the single GPS module comes out of the GP start, but if it is a dual-mode gga may be gngga,gsa and GSV words need to distinguish between GPs or Beidou, if the GPS is the general or with GPGSV, Beidou words may be bdgsv, of course, this data header needs to be based on specific modules, many modules can also be ordered to modify the data header. Here's a look at a valid two-mode log:

$GNGGA, 033327.000,2234.6973,n,11355.2708,e,1,14,0.7,55.57,m,-2.7,m,0.0,0000,1.3*70$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

From GGA,GLL can analyze its position, Gsv,gsa can see how many active satellites, its prn,snr, azimuth, there is no star calendar, and so on, the following look at the two-mode display pictures, the situation of each visible satellite:

The above satellite information is the actual road test when the screenshot down, antenna matching can also be optimized a bit, the SNR will be better. The next article describes some of the management information for the Android section location.

Application and development of GPS Beidou dual-mode technology--data analysis