// Part of BNC, a utility for retrieving decoding and // converting GNSS data streams from NTRIP broadcasters. // // Copyright (C) 2007 // German Federal Agency for Cartography and Geodesy (BKG) // http://www.bkg.bund.de // Czech Technical University Prague, Department of Geodesy // http://www.fsv.cvut.cz // // Email: euref-ip@bkg.bund.de // // This program is free software; you can redistribute it and/or // modify it under the terms of the GNU General Public License // as published by the Free Software Foundation, version 2. // // This program is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // // You should have received a copy of the GNU General Public License // along with this program; if not, write to the Free Software // Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. /* ------------------------------------------------------------------------- * BKG NTRIP Client * ------------------------------------------------------------------------- * * Class: RTCM3Decoder * * Purpose: RTCM3 Decoder * * Author: L. Mervart * * Created: 24-Aug-2006 * * Changes: * * -----------------------------------------------------------------------*/ #include #include #include #include #include #include "bits.h" #include "gnss.h" #include "RTCM3Decoder.h" #include "rtcm_utils.h" #include "bncconst.h" #include "bnccore.h" #include "bncutils.h" #include "bncsettings.h" using namespace std; // Error Handling //////////////////////////////////////////////////////////////////////////// void RTCM3Error(const char*, ...) { } // Constructor //////////////////////////////////////////////////////////////////////////// RTCM3Decoder::RTCM3Decoder(const QString& staID, bncRawFile* rawFile) : GPSDecoder() { _staID = staID; _rawFile = rawFile; connect(this, SIGNAL(newGPSEph(t_ephGPS)), BNC_CORE, SLOT(slotNewGPSEph(t_ephGPS))); connect(this, SIGNAL(newGlonassEph(t_ephGlo)), BNC_CORE, SLOT(slotNewGlonassEph(t_ephGlo))); connect(this, SIGNAL(newGalileoEph(t_ephGal)), BNC_CORE, SLOT(slotNewGalileoEph(t_ephGal))); connect(this, SIGNAL(newSBASEph(t_ephSBAS)), BNC_CORE, SLOT(slotNewSBASEph(t_ephSBAS))); connect(this, SIGNAL(newBDSEph(t_ephBDS)), BNC_CORE, SLOT(slotNewBDSEph(t_ephBDS))); _MessageSize = _SkipBytes = _BlockSize = _NeedBytes = 0; } // Destructor //////////////////////////////////////////////////////////////////////////// RTCM3Decoder::~RTCM3Decoder() { QMapIterator it(_coDecoders); while(it.hasNext()) { it.next(); delete it.value(); } } // //////////////////////////////////////////////////////////////////////////// bool RTCM3Decoder::DecodeRTCM3GPS(unsigned char* data, int size) { bool decoded = false; bncTime CurrentObsTime; int i, numsats, syncf, type; uint64_t numbits = 0, bitfield = 0; data += 3; /* header */ size -= 6; /* header + crc */ GETBITS(type, 12) SKIPBITS(12) /* id */ GETBITS(i,30) CurrentObsTime.set(i); if(_CurrentTime.valid() && CurrentObsTime != _CurrentTime) { decoded = true; _obsList.append(_CurrentObsList); _CurrentObsList.clear(); } _CurrentTime = CurrentObsTime; GETBITS(syncf,1) /* sync */ GETBITS(numsats,5) SKIPBITS(4) /* smind, smint */ while(numsats--) { int sv, code, l1range, amb=0; t_satObs CurrentObs; CurrentObs._time = CurrentObsTime; GETBITS(sv, 6) if(sv < 40) CurrentObs._prn.set('G', sv); else CurrentObs._prn.set('S', sv-20); t_frqObs *frqObs = new t_frqObs; /* L1 */ GETBITS(code, 1); frqObs->_rnxType2ch = code ? "1W" : "1C"; GETBITS(l1range, 24); GETBITSSIGN(i, 20); if((i&((1<<20)-1)) != 0x80000) { frqObs->_code = l1range*0.02; frqObs->_phase = (l1range*0.02+i*0.0005)/GPS_WAVELENGTH_L1; frqObs->_codeValid = frqObs->_phaseValid = true; } GETBITS(i, 7); frqObs->_slipCounter = i; if(type == 1002 || type == 1004) { GETBITS(amb,8); if(amb) { frqObs->_code += amb*299792.458; frqObs->_phase += (amb*299792.458)/GPS_WAVELENGTH_L1; } GETBITS(i, 8); if(i) { frqObs->_snr = i*0.25; frqObs->_snrValid = true; } } CurrentObs._obs.push_back(frqObs); if(type == 1003 || type == 1004) { frqObs = new t_frqObs; /* L2 */ GETBITS(code,2); switch(code) { case 3: frqObs->_rnxType2ch = "2W"; /* or "2Y"? */ break; case 2: frqObs->_rnxType2ch = "2W"; break; case 1: frqObs->_rnxType2ch = "2P"; break; case 0: frqObs->_rnxType2ch = "2X"; /* or "2S" or "2L"? */ break; } GETBITSSIGN(i,14); if((i&((1<<14)-1)) != 0x2000) { frqObs->_code = l1range*0.02+i*0.02+amb*299792.458; frqObs->_codeValid = true; } GETBITSSIGN(i,20); if((i&((1<<20)-1)) != 0x80000) { frqObs->_phase = (l1range*0.02+i*0.0005+amb*299792.458)/GPS_WAVELENGTH_L2; frqObs->_phaseValid = true; } GETBITS(i,7); frqObs->_slipCounter = i; if(type == 1004) { GETBITS(i, 8); if(i) { frqObs->_snr = i*0.25; frqObs->_snrValid = true; } } CurrentObs._obs.push_back(frqObs); } _CurrentObsList.push_back(CurrentObs); } if(!syncf) { decoded = true; _obsList.append(_CurrentObsList); _CurrentTime.reset(); _CurrentObsList.clear(); } return decoded; } #define RTCM3_MSM_NUMSIG 32 #define RTCM3_MSM_NUMSAT 64 #define RTCM3_MSM_NUMCELLS 96 /* arbitrary limit */ /** * Frequency numbers of GLONASS with an offset of 100 to detect unset values. * Gets filled by ephemeris and data blocks and shared between different streams. */ static int GLOFreq[RTCM3_MSM_NUMSAT]; /* * Storage structure to store frequency and RINEX ID assignment for MSM * message */ struct CodeData { double wl; const char *code; /* currently unused */ }; /** MSM signal types for GPS and SBAS */ static struct CodeData gps[RTCM3_MSM_NUMSIG] = { {0.0,0}, {GPS_WAVELENGTH_L1,"1C"}, {GPS_WAVELENGTH_L1,"1P"}, {GPS_WAVELENGTH_L1,"1W"}, {0.0,0}/*{GPS_WAVELENGTH_L1,"1Y"}*/, {0.0,0}, {0.0,0}, {GPS_WAVELENGTH_L2,"2C"}, {GPS_WAVELENGTH_L2,"2P"}, {GPS_WAVELENGTH_L2,"2W"}, {0.0,0}/*{GPS_WAVELENGTH_L2,"2Y"}*/, {0.0,0}, {0.0,0}, {0.0,0}, {GPS_WAVELENGTH_L2,"2S"}, {GPS_WAVELENGTH_L2,"2L"}, {GPS_WAVELENGTH_L2,"2X"}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {GPS_WAVELENGTH_L5,"5I"}, {GPS_WAVELENGTH_L5,"5Q"}, {GPS_WAVELENGTH_L5,"5X"}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {GPS_WAVELENGTH_L1,"1S"}, {GPS_WAVELENGTH_L1,"1L"}, {GPS_WAVELENGTH_L1,"1X"} }; /** * MSM signal types for GLONASS * * NOTE: Uses 0.0, 1.0 for wavelength as sat index dependence is done later! */ static struct CodeData glo[RTCM3_MSM_NUMSIG] = { {0.0,0}, {0.0,"1C"}, {0.0,"1P"}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {1.0,"2C"}, {1.0,"2P"}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0} }; /** MSM signal types for Galileo */ static struct CodeData gal[RTCM3_MSM_NUMSIG] = { {0.0,0}, {GAL_WAVELENGTH_E1,"1C"}, {GAL_WAVELENGTH_E1,"1A"}, {GAL_WAVELENGTH_E1,"1B"}, {GAL_WAVELENGTH_E1,"1X"}, {GAL_WAVELENGTH_E1,"1Z"}, {0.0,0}, {GAL_WAVELENGTH_E6,"6C"}, {GAL_WAVELENGTH_E6,"6A"}, {GAL_WAVELENGTH_E6,"6B"}, {GAL_WAVELENGTH_E6,"6X"}, {GAL_WAVELENGTH_E6,"6Z"}, {0.0,0}, {GAL_WAVELENGTH_E5B,"7I"}, {GAL_WAVELENGTH_E5B,"7Q"}, {GAL_WAVELENGTH_E5B,"7X"}, {0.0,0}, {GAL_WAVELENGTH_E5AB,"8I"}, {GAL_WAVELENGTH_E5AB,"8Q"}, {GAL_WAVELENGTH_E5AB,"8X"}, {0.0,0}, {GAL_WAVELENGTH_E5A,"5I"}, {GAL_WAVELENGTH_E5A,"5Q"}, {GAL_WAVELENGTH_E5A,"5X"}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, }; /** MSM signal types for QZSS */ static struct CodeData qzss[RTCM3_MSM_NUMSIG] = { {0.0,0}, {GPS_WAVELENGTH_L1,"1C"}, {0.0,0}, {0.0,0}, {0.0,0}, {GPS_WAVELENGTH_L1,"1Z"}, {0.0,0}, {0.0,0}, {QZSS_WAVELENGTH_LEX,"6S"}, {QZSS_WAVELENGTH_LEX,"6L"}, {QZSS_WAVELENGTH_LEX,"6X"}, {0.0,0}, {0.0,0}, {0.0,0}, {GPS_WAVELENGTH_L2,"2S"}, {GPS_WAVELENGTH_L2,"2L"}, {GPS_WAVELENGTH_L2,"2X"}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {GPS_WAVELENGTH_L5,"5I"}, {GPS_WAVELENGTH_L5,"5Q"}, {GPS_WAVELENGTH_L5,"5X"}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {GPS_WAVELENGTH_L1,"1D"}, {GPS_WAVELENGTH_L1,"1P"}, {GPS_WAVELENGTH_L1,"1X"} }; /** MSM signal types for Beidou/BDS */ static struct CodeData bds[RTCM3_MSM_NUMSIG] = { {0.0,0}, {BDS_WAVELENGTH_B1,"2I"}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {BDS_WAVELENGTH_B3,"6I"}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {BDS_WAVELENGTH_B2,"7I"}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, {0.0,0}, }; #define UINT64(c) c ## ULL // //////////////////////////////////////////////////////////////////////////// bool RTCM3Decoder::DecodeRTCM3MSM(unsigned char* data, int size) { bool decoded = false; int type, syncf, i; uint64_t numbits = 0, bitfield = 0; data += 3; /* header */ size -= 6; /* header + crc */ GETBITS(type, 12) SKIPBITS(12) /* id */ char sys; if(type >= 1121) sys = 'C'; else if(type >= 1111) sys = 'J'; else if(type >= 1101) sys = 'S'; else if(type >= 1091) sys = 'E'; else if(type >= 1081) sys = 'R'; else sys = 'G'; bncTime CurrentObsTime; if(sys == 'C') /* BDS */ { GETBITS(i,30) CurrentObsTime.setBDS(i); } else if(sys == 'R') /* GLONASS */ { SKIPBITS(3) GETBITS(i,27) /* tk */ CurrentObsTime.setTk(i); } else /* GPS style date */ { GETBITS(i,30) CurrentObsTime.set(i); } if(_CurrentTime.valid() && CurrentObsTime != _CurrentTime) { decoded = true; _obsList = _CurrentObsList; _CurrentObsList.clear(); } _CurrentTime = CurrentObsTime; GETBITS(syncf, 1) /** * Ignore unknown types except for sync flag * * We actually support types 1-3 in following code, but as they are missing * the full cycles and can't be used later we skip interpretation here already. */ if(type <= 1130 && (type % 10) >= 4 && (type % 10) <= 7) { int sigmask, numsat = 0, numsig = 0; uint64_t satmask, cellmask, ui; double rrmod[RTCM3_MSM_NUMSAT]; int rrint[RTCM3_MSM_NUMSAT], rdop[RTCM3_MSM_NUMSAT], extsat[RTCM3_MSM_NUMSAT]; int ll[RTCM3_MSM_NUMCELLS]/*, hc[RTCM3_MSM_NUMCELLS]*/; double cnr[RTCM3_MSM_NUMCELLS]; double cp[RTCM3_MSM_NUMCELLS], psr[RTCM3_MSM_NUMCELLS], dop[RTCM3_MSM_NUMCELLS]; SKIPBITS(3+7+2+2+1+3) GETBITS64(satmask, RTCM3_MSM_NUMSAT) /* http://gurmeetsingh.wordpress.com/2008/08/05/fast-bit-counting-routines/ */ for(ui = satmask; ui; ui &= (ui - 1) /* remove rightmost bit */) ++numsat; GETBITS(sigmask, RTCM3_MSM_NUMSIG) for(i = sigmask; i; i &= (i - 1) /* remove rightmost bit */) ++numsig; for(i = 0; i < RTCM3_MSM_NUMSAT; ++i) extsat[i] = 15; i = numsat*numsig; GETBITS64(cellmask, (unsigned)i) switch(type % 10) { case 1: case 2: case 3: /* partial data, already skipped above, but implemented for future expansion ! */ for(int j = numsat; j--;) GETFLOAT(rrmod[j], 10, 1.0/1024.0) break; case 4: case 6: for(int j = numsat; j--;) GETBITS(rrint[j], 8) for(int j = numsat; j--;) GETFLOAT(rrmod[j], 10, 1.0/1024.0) break; case 5: case 7: for(int j = numsat; j--;) GETBITS(rrint[j], 8) for(int j = numsat; j--;) GETBITS(extsat[j], 4) for(int j = numsat; j--;) GETFLOAT(rrmod[j], 10, 1.0/1024.0) for(int j = numsat; j--;) GETBITSSIGN(rdop[j], 14) break; } int numcells = numsat*numsig; /** Drop anything which exceeds our cell limit. Increase limit definition * when that happens. */ if(numcells <= RTCM3_MSM_NUMCELLS) { switch(type % 10) { case 1: for(int count = numcells; count--;) if(cellmask & (UINT64(1)<= 0 && !(sigmask&(1<<--j))) ; if(j < 0) { while(!(satmask&(UINT64(1)<<(--i)))) /* next satellite */ ; if(CurrentObs._obs.size() > 0) _CurrentObsList.push_back(CurrentObs); CurrentObs.clear(); CurrentObs._time = CurrentObsTime; if(sys == 'S') CurrentObs._prn.set(sys, 20-1+RTCM3_MSM_NUMSAT-i); else CurrentObs._prn.set(sys, RTCM3_MSM_NUMSAT-i); j = RTCM3_MSM_NUMSIG; while(!(sigmask&(1<<--j))) ; --numsat; } if(cellmask & (UINT64(1)<_rnxType2ch = cd.code; switch(type % 10) { case 1: if(psr[count] > -1.0/(1<<10)) { frqObs->_code = psr[count]*LIGHTSPEED/1000.0 +(rrmod[numsat])*LIGHTSPEED/1000.0; frqObs->_codeValid = true; } break; case 2: if(cp[count] > -1.0/(1<<8)) { frqObs->_phase = cp[count]*LIGHTSPEED/1000.0/cd.wl +(rrmod[numsat])*LIGHTSPEED/1000.0/cd.wl; frqObs->_phaseValid = true; frqObs->_slipCounter = ll[count]; } break; case 3: if(psr[count] > -1.0/(1<<10)) { frqObs->_code = psr[count]*LIGHTSPEED/1000.0 +(rrmod[numsat])*LIGHTSPEED/1000.0; frqObs->_codeValid = true; } if(cp[count] > -1.0/(1<<8)) { frqObs->_phase = cp[count]*LIGHTSPEED/1000.0/cd.wl +rrmod[numsat]*LIGHTSPEED/1000.0/cd.wl; frqObs->_phaseValid = true; frqObs->_slipCounter = ll[count]; } break; case 4: if(psr[count] > -1.0/(1<<10)) { frqObs->_code = psr[count]*LIGHTSPEED/1000.0 +(rrmod[numsat]+rrint[numsat])*LIGHTSPEED/1000.0; frqObs->_codeValid = true; } if(cp[count] > -1.0/(1<<8)) { frqObs->_phase = cp[count]*LIGHTSPEED/1000.0/cd.wl +(rrmod[numsat]+rrint[numsat])*LIGHTSPEED/1000.0/cd.wl; frqObs->_phaseValid = true; frqObs->_slipCounter = ll[count]; } frqObs->_snr = cnr[count]; frqObs->_snrValid = true; break; case 5: if(psr[count] > -1.0/(1<<10)) { frqObs->_code = psr[count]*LIGHTSPEED/1000.0 +(rrmod[numsat]+rrint[numsat])*LIGHTSPEED/1000.0; frqObs->_codeValid = true; } if(cp[count] > -1.0/(1<<8)) { frqObs->_phase = cp[count]*LIGHTSPEED/1000.0/cd.wl +(rrmod[numsat]+rrint[numsat])*LIGHTSPEED/1000.0/cd.wl; frqObs->_phaseValid = true; frqObs->_slipCounter = ll[count]; } frqObs->_snr = cnr[count]; frqObs->_snrValid = true; if(dop[count] > -1.6384) { frqObs->_doppler = -(dop[count]+rdop[numsat])/cd.wl; frqObs->_dopplerValid = true; } break; case 6: if(psr[count] > -1.0/(1<<10)) { frqObs->_code = psr[count]*LIGHTSPEED/1000.0 +(rrmod[numsat]+rrint[numsat])*LIGHTSPEED/1000.0; frqObs->_codeValid = true; } if(cp[count] > -1.0/(1<<8)) { frqObs->_phase = cp[count]*LIGHTSPEED/1000.0/cd.wl +(rrmod[numsat]+rrint[numsat])*LIGHTSPEED/1000.0/cd.wl; frqObs->_phaseValid = true; frqObs->_slipCounter = ll[count]; } frqObs->_snr = cnr[count]; frqObs->_snrValid = true; break; case 7: if(psr[count] > -1.0/(1<<10)) { frqObs->_code = psr[count]*LIGHTSPEED/1000.0 +(rrmod[numsat]+rrint[numsat])*LIGHTSPEED/1000.0; frqObs->_codeValid = true; } if(cp[count] > -1.0/(1<<8)) { frqObs->_phase = cp[count]*LIGHTSPEED/1000.0/cd.wl +(rrmod[numsat]+rrint[numsat])*LIGHTSPEED/1000.0/cd.wl; frqObs->_phaseValid = true; frqObs->_slipCounter = ll[count]; } frqObs->_snr = cnr[count]; frqObs->_snrValid = true; if(dop[count] > -1.6384) { frqObs->_doppler = -(dop[count]+rdop[numsat])/cd.wl; frqObs->_dopplerValid = true; } break; } CurrentObs._obs.push_back(frqObs); } } } if(CurrentObs._obs.size() > 0) _CurrentObsList.push_back(CurrentObs); } } else if((type % 10) < 3) { emit(newMessage(QString("%1: Block %2 contain partial data! Ignored!") .arg(_staID).arg(type).toAscii(), true)); } if(!syncf) { decoded = true; _obsList = _CurrentObsList; _CurrentTime.reset(); _CurrentObsList.clear(); } return decoded; } // //////////////////////////////////////////////////////////////////////////// bool RTCM3Decoder::DecodeRTCM3GLONASS(unsigned char* data, int size) { bool decoded = false; bncTime CurrentObsTime; int i, numsats, syncf, type; uint64_t numbits = 0, bitfield = 0; data += 3; /* header */ size -= 6; /* header + crc */ GETBITS(type, 12) SKIPBITS(12) /* id */ GETBITS(i,27) /* tk */ CurrentObsTime.setTk(i); if(_CurrentTime.valid() && CurrentObsTime != _CurrentTime) { decoded = true; _obsList.append(_CurrentObsList); _CurrentObsList.clear(); } _CurrentTime = CurrentObsTime; GETBITS(syncf,1) /* sync */ GETBITS(numsats,5) SKIPBITS(4) /* smind, smint */ while(numsats--) { int sv, code, l1range, amb=0, freq; t_satObs CurrentObs; CurrentObs._time = CurrentObsTime; GETBITS(sv, 6) CurrentObs._prn.set('R', sv); GETBITS(code, 1) GETBITS(freq, 5) GLOFreq[sv-1] = 100+freq-7; /* store frequency for other users (MSM) */ t_frqObs *frqObs = new t_frqObs; /* L1 */ frqObs->_rnxType2ch = code ? "1P" : "1C"; GETBITS(l1range, 25); GETBITSSIGN(i, 20); if((i&((1<<20)-1)) != 0x80000) { frqObs->_code = l1range*0.02; frqObs->_phase = (l1range*0.02+i*0.0005)/GLO_WAVELENGTH_L1(freq-7); frqObs->_codeValid = frqObs->_phaseValid = true; } GETBITS(i, 7); frqObs->_slipCounter = i; if(type == 1010 || type == 1012) { GETBITS(amb,7); if(amb) { frqObs->_code += amb*599584.916; frqObs->_phase += (amb*599584.916)/GLO_WAVELENGTH_L1(freq-7); } GETBITS(i, 8); if(i) { frqObs->_snr = i*0.25; frqObs->_snrValid = true; } } CurrentObs._obs.push_back(frqObs); if(type == 1011 || type == 1012) { frqObs = new t_frqObs; /* L2 */ GETBITS(code,2); switch(code) { case 3: frqObs->_rnxType2ch = "2P"; break; case 2: frqObs->_rnxType2ch = "2P"; break; case 1: frqObs->_rnxType2ch = "2P"; break; case 0: frqObs->_rnxType2ch = "2C"; break; } GETBITSSIGN(i,14); if((i&((1<<14)-1)) != 0x2000) { frqObs->_code = l1range*0.02+i*0.02+amb*599584.916; frqObs->_codeValid = true; } GETBITSSIGN(i,20); if((i&((1<<20)-1)) != 0x80000) { frqObs->_phase = (l1range*0.02+i*0.0005+amb*599584.916)/GLO_WAVELENGTH_L2(freq-7); frqObs->_phaseValid = true; } GETBITS(i,7); frqObs->_slipCounter = i; if(type == 1012) { GETBITS(i, 8); if(i) { frqObs->_snr = i*0.25; frqObs->_snrValid = true; } } CurrentObs._obs.push_back(frqObs); } _CurrentObsList.push_back(CurrentObs); } if(!syncf) { decoded = true; _obsList.append(_CurrentObsList); _CurrentTime.reset(); _CurrentObsList.clear(); } return decoded; } // //////////////////////////////////////////////////////////////////////////// bool RTCM3Decoder::DecodeGPSEphemeris(unsigned char* data, int size) { bool decoded = false; if(size == 67) { t_ephGPS eph; int i, week; uint64_t numbits = 0, bitfield = 0; data += 3; /* header */ size -= 6; /* header + crc */ SKIPBITS(12) eph._receptDateTime = currentDateAndTimeGPS(); GETBITS(i, 6) eph._prn.set('G', i); GETBITS(week, 10) week += 1024; GETBITS(i, 4) eph._ura = accuracyFromIndex(i, eph.type()); GETBITS(eph._L2Codes, 2) GETFLOATSIGN(eph._IDOT, 14, R2R_PI/(double)(1<<30)/(double)(1<<13)) GETBITS(eph._IODE, 8) GETBITS(i, 16) i <<= 4; eph._TOC.set(i*1000); GETFLOATSIGN(eph._clock_driftrate, 8, 1.0/(double)(1<<30)/(double)(1<<25)) GETFLOATSIGN(eph._clock_drift, 16, 1.0/(double)(1<<30)/(double)(1<<13)) GETFLOATSIGN(eph._clock_bias, 22, 1.0/(double)(1<<30)/(double)(1<<1)) GETBITS(eph._IODC, 10) GETFLOATSIGN(eph._Crs, 16, 1.0/(double)(1<<5)) GETFLOATSIGN(eph._Delta_n, 16, R2R_PI/(double)(1<<30)/(double)(1<<13)) GETFLOATSIGN(eph._M0, 32, R2R_PI/(double)(1<<30)/(double)(1<<1)) GETFLOATSIGN(eph._Cuc, 16, 1.0/(double)(1<<29)) GETFLOAT(eph._e, 32, 1.0/(double)(1<<30)/(double)(1<<3)) GETFLOATSIGN(eph._Cus, 16, 1.0/(double)(1<<29)) GETFLOAT(eph._sqrt_A, 32, 1.0/(double)(1<<19)) GETBITS(i, 16) i <<= 4; eph._TOEsec = i; bncTime t; t.set(i*1000); eph._TOEweek = t.gpsw(); /* week from HOW, differs from TOC, TOE week, we use adapted value instead */ if(eph._TOEweek > week + 1 || eph._TOEweek < week-1) /* invalid week */ return false; GETFLOATSIGN(eph._Cic, 16, 1.0/(double)(1<<29)) GETFLOATSIGN(eph._OMEGA0, 32, R2R_PI/(double)(1<<30)/(double)(1<<1)) GETFLOATSIGN(eph._Cis, 16, 1.0/(double)(1<<29)) GETFLOATSIGN(eph._i0, 32, R2R_PI/(double)(1<<30)/(double)(1<<1)) GETFLOATSIGN(eph._Crc, 16, 1.0/(double)(1<<5)) GETFLOATSIGN(eph._omega, 32, R2R_PI/(double)(1<<30)/(double)(1<<1)) GETFLOATSIGN(eph._OMEGADOT, 24, R2R_PI/(double)(1<<30)/(double)(1<<13)) GETFLOATSIGN(eph._TGD, 8, 1.0/(double)(1<<30)/(double)(1<<1)) GETBITS(eph._health, 6) GETBITS(eph._L2PFlag, 1) GETBITS(eph._fitInterval, 1) eph._TOT = 0.9999e9; emit newGPSEph(eph); decoded = true; } return decoded; } // //////////////////////////////////////////////////////////////////////////// bool RTCM3Decoder::DecodeGLONASSEphemeris(unsigned char* data, int size) { bool decoded = false; if(size == 51) { t_ephGlo eph; int sv, i, tk; uint64_t numbits = 0, bitfield = 0; data += 3; /* header */ size -= 6; /* header + crc */ SKIPBITS(12) eph._receptDateTime = currentDateAndTimeGPS(); GETBITS(sv, 6) eph._prn.set('R', sv); GETBITS(i, 5) eph._frequency_number = i-7; GLOFreq[sv-1] = 100+i-7; /* store frequency for other users (MSM) */ _gloFrq = QString("%1 %2").arg(eph._prn.toString().c_str()).arg(eph._frequency_number,2,'f',0); SKIPBITS(4) /* almanac healthy, almanac health ok, P1 */ GETBITS(i, 5) tk = i*60*60; GETBITS(i, 6) tk += i*60; GETBITS(i, 1) tk += i*30; eph._tki = tk < 3*60*60 ? tk-3*60*60+86400 : tk-3*60*60; GETBITS(eph._health, 1) SKIPBITS(1) /* P2 */ GETBITS(i, 7) eph._TOC.setTk(i*15*60*1000); /* tb */ GETFLOATSIGNM(eph._x_velocity, 24, 1.0/(double)(1<<20)) GETFLOATSIGNM(eph._x_pos, 27, 1.0/(double)(1<<11)) GETFLOATSIGNM(eph._x_acceleration, 5, 1.0/(double)(1<<30)) GETFLOATSIGNM(eph._y_velocity, 24, 1.0/(double)(1<<20)) GETFLOATSIGNM(eph._y_pos, 27, 1.0/(double)(1<<11)) GETFLOATSIGNM(eph._y_acceleration, 5, 1.0/(double)(1<<30)) GETFLOATSIGNM(eph._z_velocity, 24, 1.0/(double)(1<<20)) GETFLOATSIGNM(eph._z_pos, 27, 1.0/(double)(1<<11)) GETFLOATSIGNM(eph._z_acceleration, 5, 1.0/(double)(1<<30)) SKIPBITS(1) /* P3 */ GETFLOATSIGNM(eph._gamma, 11, 1.0/(double)(1<<30)/(double)(1<<10)) SKIPBITS(3) /* GLONASS-M P, GLONASS-M ln (third string) */ GETFLOATSIGNM(eph._tau, 22, 1.0/(double)(1<<30)) /* GLONASS tau n(tb) */ SKIPBITS(5) /* GLONASS-M delta tau n(tb) */ GETBITS(eph._E, 5) /* GETBITS(i, 1) / * GLONASS-M P4 */ /* GETBITS(i, 4) / * GLONASS-M Ft */ /* GETBITS(i, 11) / * GLONASS-M Nt */ /* GETBITS(i, 2) / * GLONASS-M M */ /* GETBITS(i, 1) / * GLONASS-M The Availability of Additional Data */ /* GETBITS(i, 11) / * GLONASS-M Na */ /* GETFLOATSIGNM(i, 32, 1.0/(double)(1<<30)/(double)(1<<1)) / * GLONASS tau c */ /* GETBITS(i, 5) / * GLONASS-M N4 */ /* GETFLOATSIGNM(i, 22, 1.0/(double)(1<<30)) / * GLONASS-M tau GPS */ /* GETBITS(i, 1) / * GLONASS-M ln (fifth string) */ unsigned year, month, day; eph._TOC.civil_date(year, month, day); eph._gps_utc = gnumleap(year, month, day); eph._tt = eph._TOC; eph._xv(1) = eph._x_pos * 1.e3; eph._xv(2) = eph._y_pos * 1.e3; eph._xv(3) = eph._z_pos * 1.e3; eph._xv(4) = eph._x_velocity * 1.e3; eph._xv(5) = eph._y_velocity * 1.e3; eph._xv(6) = eph._z_velocity * 1.e3; emit newGlonassEph(eph); decoded = true; } return decoded; } // //////////////////////////////////////////////////////////////////////////// bool RTCM3Decoder::DecodeQZSSEphemeris(unsigned char* data, int size) { bool decoded = false; if(size == 67) { t_ephGPS eph; int i, week; uint64_t numbits = 0, bitfield = 0; data += 3; /* header */ size -= 6; /* header + crc */ SKIPBITS(12) eph._receptDateTime = currentDateAndTimeGPS(); GETBITS(i, 4) eph._prn.set('J', i); GETBITS(i, 16) i <<= 4; eph._TOC.set(i*1000); GETFLOATSIGN(eph._clock_driftrate, 8, 1.0/(double)(1<<30)/(double)(1<<25)) GETFLOATSIGN(eph._clock_drift, 16, 1.0/(double)(1<<30)/(double)(1<<13)) GETFLOATSIGN(eph._clock_bias, 22, 1.0/(double)(1<<30)/(double)(1<<1)) GETBITS(eph._IODE, 8) GETFLOATSIGN(eph._Crs, 16, 1.0/(double)(1<<5)) GETFLOATSIGN(eph._Delta_n, 16, R2R_PI/(double)(1<<30)/(double)(1<<13)) GETFLOATSIGN(eph._M0, 32, R2R_PI/(double)(1<<30)/(double)(1<<1)) GETFLOATSIGN(eph._Cuc, 16, 1.0/(double)(1<<29)) GETFLOAT(eph._e, 32, 1.0/(double)(1<<30)/(double)(1<<3)) GETFLOATSIGN(eph._Cus, 16, 1.0/(double)(1<<29)) GETFLOAT(eph._sqrt_A, 32, 1.0/(double)(1<<19)) GETBITS(i, 16) i <<= 4; eph._TOEsec = i; bncTime t; t.set(i); GETFLOATSIGN(eph._Cic, 16, 1.0/(double)(1<<29)) GETFLOATSIGN(eph._OMEGA0, 32, R2R_PI/(double)(1<<30)/(double)(1<<1)) GETFLOATSIGN(eph._Cis, 16, 1.0/(double)(1<<29)) GETFLOATSIGN(eph._i0, 32, R2R_PI/(double)(1<<30)/(double)(1<<1)) GETFLOATSIGN(eph._Crc, 16, 1.0/(double)(1<<5)) GETFLOATSIGN(eph._omega, 32, R2R_PI/(double)(1<<30)/(double)(1<<1)) GETFLOATSIGN(eph._OMEGADOT, 24, R2R_PI/(double)(1<<30)/(double)(1<<13)) GETFLOATSIGN(eph._IDOT, 14, R2R_PI/(double)(1<<30)/(double)(1<<13)) GETBITS(eph._L2Codes, 2) GETBITS(week, 10) week += 1024; eph._TOEweek = t.gpsw(); /* week from HOW, differs from TOC, TOE week, we use adapted value instead */ if(eph._TOEweek > week + 1 || eph._TOEweek < week-1) /* invalid week */ return false; GETBITS(i, 4) if(i <= 6) eph._ura = ceil(10.0*pow(2.0, 1.0+i/2.0))/10.0; else eph._ura = ceil(10.0*pow(2.0, i/2.0))/10.0; GETBITS(eph._health, 6) GETFLOATSIGN(eph._TGD, 8, 1.0/(double)(1<<30)/(double)(1<<1)) GETBITS(eph._IODC, 10) GETBITS(eph._fitInterval, 1) eph._TOT = 0.9999e9; eph._L2PFlag = 0; /* does not exist for QZSS */ emit newGPSEph(eph); decoded = true; } return decoded; } // //////////////////////////////////////////////////////////////////////////// bool RTCM3Decoder::DecodeSBASEphemeris(unsigned char* data, int size) { bool decoded = false; if(size == 35) { t_ephSBAS eph; int i; uint64_t numbits = 0, bitfield = 0; data += 3; /* header */ size -= 6; /* header + crc */ SKIPBITS(12) eph._receptDateTime = currentDateAndTimeGPS(); GETBITS(i, 6) eph._prn.set('S', 20+i); GETBITS(eph._IODN, 8) GETBITS(i, 13) i <<= 4; eph._TOC.setTOD(i*1000); GETBITS(i, 4) eph._ura = accuracyFromIndex(i, eph.type()); GETFLOATSIGN(eph._x_pos, 30, 0.08) GETFLOATSIGN(eph._y_pos, 30, 0.08) GETFLOATSIGN(eph._z_pos, 25, 0.4) GETFLOATSIGN(eph._x_velocity, 17, 0.000625) GETFLOATSIGN(eph._y_velocity, 17, 0.000625) GETFLOATSIGN(eph._z_velocity, 18, 0.004) GETFLOATSIGN(eph._x_acceleration, 10, 0.0000125) GETFLOATSIGN(eph._y_acceleration, 10, 0.0000125) GETFLOATSIGN(eph._z_acceleration, 10, 0.0000625) GETFLOATSIGN(eph._agf0, 12, 1.0/(1<<30)/(1<<1)) GETFLOATSIGN(eph._agf1, 8, 1.0/(1<<30)/(1<<10)) eph._TOW = 0.9999E9; eph._health = 0; emit newSBASEph(eph); decoded = true; } return decoded; } // //////////////////////////////////////////////////////////////////////////// bool RTCM3Decoder::DecodeGalileoEphemeris(unsigned char* data, int size) { bool decoded = false; uint64_t numbits = 0, bitfield = 0; int i; data += 3; /* header */ size -= 6; /* header + crc */ GETBITS(i, 12) if((i == 1046 && size == 61) || (i == 1045 && size == 60)) { t_ephGal eph; eph._receptDateTime = currentDateAndTimeGPS(); eph._inav = (i == 1046); eph._fnav = (i == 1045); GETBITS(i, 6) eph._prn.set('E', i, eph._inav ? 1 : 0); GETBITS(eph._TOEweek, 12) GETBITS(eph._IODnav, 10) GETBITS(i, 8) eph._SISA = accuracyFromIndex(i, eph.type()); GETFLOATSIGN(eph._IDOT, 14, R2R_PI/(double)(1<<30)/(double)(1<<13)) GETBITSFACTOR(i, 14, 60) eph._TOC.set(1024+eph._TOEweek, i); GETFLOATSIGN(eph._clock_driftrate, 6, 1.0/(double)(1<<30)/(double)(1<<29)) GETFLOATSIGN(eph._clock_drift, 21, 1.0/(double)(1<<30)/(double)(1<<16)) GETFLOATSIGN(eph._clock_bias, 31, 1.0/(double)(1<<30)/(double)(1<<4)) GETFLOATSIGN(eph._Crs, 16, 1.0/(double)(1<<5)) GETFLOATSIGN(eph._Delta_n, 16, R2R_PI/(double)(1<<30)/(double)(1<<13)) GETFLOATSIGN(eph._M0, 32, R2R_PI/(double)(1<<30)/(double)(1<<1)) GETFLOATSIGN(eph._Cuc, 16, 1.0/(double)(1<<29)) GETFLOAT(eph._e, 32, 1.0/(double)(1<<30)/(double)(1<<3)) GETFLOATSIGN(eph._Cus, 16, 1.0/(double)(1<<29)) GETFLOAT(eph._sqrt_A, 32, 1.0/(double)(1<<19)) GETBITSFACTOR(eph._TOEsec, 14, 60) /* FIXME: overwrite value, copied from old code */ eph._TOEsec = eph._TOC.gpssec(); GETFLOATSIGN(eph._Cic, 16, 1.0/(double)(1<<29)) GETFLOATSIGN(eph._OMEGA0, 32, R2R_PI/(double)(1<<30)/(double)(1<<1)) GETFLOATSIGN(eph._Cis, 16, 1.0/(double)(1<<29)) GETFLOATSIGN(eph._i0, 32, R2R_PI/(double)(1<<30)/(double)(1<<1)) GETFLOATSIGN(eph._Crc, 16, 1.0/(double)(1<<5)) GETFLOATSIGN(eph._omega, 32, R2R_PI/(double)(1<<30)/(double)(1<<1)) GETFLOATSIGN(eph._OMEGADOT, 24, R2R_PI/(double)(1<<30)/(double)(1<<13)) GETFLOATSIGN(eph._BGD_1_5A, 10, 1.0/(double)(1<<30)/(double)(1<<2)) if(eph._inav) { /* set unused F/NAV values */ eph._E5aHS = 0.0; eph._e5aDataInValid = false; GETFLOATSIGN(eph._BGD_1_5B, 10, 1.0/(double)(1<<30)/(double)(1<<2)) GETBITS(eph._E5bHS, 2) GETBITS(eph._e5bDataInValid, 1) GETBITS(eph._E1_bHS, 2) GETBITS(eph._e1DataInValid, 1) } else { /* set unused I/NAV values */ eph._BGD_1_5B = 0.0; eph._E5bHS = 0.0; eph._E1_bHS = 0.0; eph._e1DataInValid = false; eph._e5bDataInValid = false; GETBITS(eph._E5aHS, 2) GETBITS(eph._e5aDataInValid, 1) } eph._TOT = 0.9999e9; emit newGalileoEph(eph); decoded = true; } return decoded; } // //////////////////////////////////////////////////////////////////////////// bool RTCM3Decoder::DecodeBDSEphemeris(unsigned char* data, int size) { bool decoded = false; if(size == 70) { t_ephBDS eph; int i; uint64_t numbits = 0, bitfield = 0; data += 3; /* header */ size -= 6; /* header + crc */ SKIPBITS(12) eph._receptDateTime = currentDateAndTimeGPS(); GETBITS(i, 6) eph._prn.set('C', i); SKIPBITS(13) /* week */ GETBITS(i, 4) eph._URA = accuracyFromIndex(i, eph.type()); GETFLOATSIGN(eph._IDOT, 14, R2R_PI/(double)(1<<30)/(double)(1<<13)) GETBITS(eph._AODE, 5) GETBITS(i, 17) i <<= 3; eph._TOC.setBDS(i*1000); GETFLOATSIGN(eph._clock_driftrate, 11, 1.0/(double)(1<<30)/(double)(1<<30)/(double)(1<<6)) GETFLOATSIGN(eph._clock_drift, 22, 1.0/(double)(1<<30)/(double)(1<<20)) GETFLOATSIGN(eph._clock_bias, 24, 1.0/(double)(1<<30)/(double)(1<<3)) GETBITS(eph._AODC, 5) GETFLOATSIGN(eph._Crs, 18, 1.0/(double)(1<<6)) GETFLOATSIGN(eph._Delta_n, 16, R2R_PI/(double)(1<<30)/(double)(1<<13)) GETFLOATSIGN(eph._M0, 32, R2R_PI/(double)(1<<30)/(double)(1<<1)) GETFLOATSIGN(eph._Cuc, 18, 1.0/(double)(1<<30)/(double)(1<<1)) GETFLOAT(eph._e, 32, 1.0/(double)(1<<30)/(double)(1<<3)) GETFLOATSIGN(eph._Cus, 18, 1.0/(double)(1<<30)/(double)(1<<1)) GETFLOAT(eph._sqrt_A, 32, 1.0/(double)(1<<19)) GETBITS(i, 17) i <<= 3; eph._TOEsec = i; eph._TOE.setBDS(i*1000); GETFLOATSIGN(eph._Cic, 18, 1.0/(double)(1<<30)/(double)(1<<1)) GETFLOATSIGN(eph._OMEGA0, 32, R2R_PI/(double)(1<<30)/(double)(1<<1)) GETFLOATSIGN(eph._Cis, 18, 1.0/(double)(1<<30)/(double)(1<<1)) GETFLOATSIGN(eph._i0, 32, R2R_PI/(double)(1<<30)/(double)(1<<1)) GETFLOATSIGN(eph._Crc, 18, 1.0/(double)(1<<6)) GETFLOATSIGN(eph._omega, 32, R2R_PI/(double)(1<<30)/(double)(1<<1)) GETFLOATSIGN(eph._OMEGADOT, 24, R2R_PI/(double)(1<<30)/(double)(1<<13)) GETFLOATSIGN(eph._TGD1, 10, 0.0000000001) GETFLOATSIGN(eph._TGD2, 10, 0.0000000001) GETBITS(eph._SatH1, 1) eph._TOW = 0.9999E9; emit newBDSEph(eph); decoded = true; } return decoded; } // //////////////////////////////////////////////////////////////////////////// bool RTCM3Decoder::DecodeAntenna(unsigned char* data, int size) { char *antenna; int antnum; uint64_t numbits = 0, bitfield = 0; data += 4; /* header */ size -= 6; /* header + crc */ SKIPBITS(12) GETSTRING(antnum,antenna) _antType.push_back(antenna); return true; } // //////////////////////////////////////////////////////////////////////////// bool RTCM3Decoder::DecodeAntennaPosition(unsigned char* data, int size) { int type; uint64_t numbits = 0, bitfield = 0; double x, y, z; data += 3; /* header */ size -= 6; /* header + crc */ GETBITS(type, 12) _antList.push_back(t_antInfo()); _antList.back().type = t_antInfo::ARP; SKIPBITS(22) GETBITSSIGN(x, 38) _antList.back().xx = x * 1e-4; SKIPBITS(2) GETBITSSIGN(y, 38) _antList.back().yy = y * 1e-4; SKIPBITS(2) GETBITSSIGN(z, 38) _antList.back().zz = z * 1e-4; if(type == 1006) { double h; GETBITS(h, 16) _antList.back().height = h * 1e-4; _antList.back().height_f = true; } _antList.back().message = type; return true; } // //////////////////////////////////////////////////////////////////////////// t_irc RTCM3Decoder::Decode(char* buffer, int bufLen, vector& errmsg) { bool decoded = false; errmsg.clear(); while(bufLen && _MessageSize < sizeof(_Message)) { int l = sizeof(_Message) - _MessageSize; if(l > bufLen) l = bufLen; memcpy(_Message+_MessageSize, buffer, l); _MessageSize += l; bufLen -= l; buffer += l; int id; while((id = GetMessage())) { /* reset station ID for file loading as it can change */ if(_rawFile) _staID = _rawFile->staID(); /* store the id into the list of loaded blocks */ _typeList.push_back(id); /* SSR I+II data handled in another function, already pass the * extracted data block. That does no harm, as it anyway skip everything * else. */ if((id >= 1057 && id <= 1068) || (id >= 1240 && id <= 1270)) { if (!_coDecoders.contains(_staID.toAscii())) _coDecoders[_staID.toAscii()] = new RTCM3coDecoder(_staID); RTCM3coDecoder* coDecoder = _coDecoders[_staID.toAscii()]; if(coDecoder->Decode(reinterpret_cast(_Message), _BlockSize, errmsg) == success) { decoded = true; } } else if(id >= 1070 && id <= 1229) /* MSM */ { if(DecodeRTCM3MSM(_Message, _BlockSize)) decoded = true; } else { switch(id) { case 1001: case 1003: emit(newMessage(QString("%1: Block %2 contain partial data! Ignored!") .arg(_staID).arg(id).toAscii(), true)); break; /* no use decoding partial data ATM, remove break when data can be used */ case 1002: case 1004: if(DecodeRTCM3GPS(_Message, _BlockSize)) decoded = true; break; case 1009: case 1011: emit(newMessage(QString("%1: Block %2 contain partial data! Ignored!") .arg(_staID).arg(id).toAscii(), true)); break; /* no use decoding partial data ATM, remove break when data can be used */ case 1010: case 1012: if(DecodeRTCM3GLONASS(_Message, _BlockSize)) decoded = true; break; case 1019: if(DecodeGPSEphemeris(_Message, _BlockSize)) decoded = true; break; case 1020: if(DecodeGLONASSEphemeris(_Message, _BlockSize)) decoded = true; break; case 1043: if(DecodeSBASEphemeris(_Message, _BlockSize)) decoded = true; break; case 1044: if(DecodeQZSSEphemeris(_Message, _BlockSize)) decoded = true; break; case 1045: case 1046: if(DecodeGalileoEphemeris(_Message, _BlockSize)) decoded = true; break; case RTCM3ID_BDS: if(DecodeBDSEphemeris(_Message, _BlockSize)) decoded = true; break; case 1007: case 1008: case 1033: DecodeAntenna(_Message, _BlockSize); break; case 1005: case 1006: DecodeAntennaPosition(_Message, _BlockSize); break; } } } } return decoded ? success : failure; }; // //////////////////////////////////////////////////////////////////////////// uint32_t RTCM3Decoder::CRC24(long size, const unsigned char *buf) { uint32_t crc = 0; int i; while(size--) { crc ^= (*buf++) << (16); for(i = 0; i < 8; i++) { crc <<= 1; if(crc & 0x1000000) crc ^= 0x01864cfb; } } return crc; } // //////////////////////////////////////////////////////////////////////////// int RTCM3Decoder::GetMessage(void) { unsigned char *m, *e; int i; m = _Message+_SkipBytes; e = _Message+_MessageSize; _NeedBytes = _SkipBytes = 0; while(e-m >= 3) { if(m[0] == 0xD3) { _BlockSize = ((m[1]&3)<<8)|m[2]; if(e-m >= static_cast(_BlockSize+6)) { if(static_cast((m[3+_BlockSize]<<16)|(m[3+_BlockSize+1]<<8) |(m[3+_BlockSize+2])) == CRC24(_BlockSize+3, m)) { _BlockSize +=6; _SkipBytes = _BlockSize; break; } else ++m; } else { _NeedBytes = _BlockSize; break; } } else ++m; } if(e-m < 3) _NeedBytes = 3; /* copy buffer to front */ i = m - _Message; if(i && m < e) memmove(_Message, m, static_cast(_MessageSize-i)); _MessageSize -= i; return !_NeedBytes ? ((_Message[3]<<4)|(_Message[4]>>4)) : 0; } // Time of Corrections ////////////////////////////////////////////////////////////////////////////// int RTCM3Decoder::corrGPSEpochTime() const { return _coDecoders.size() > 0 ? _coDecoders.begin().value()->corrGPSEpochTime() : -1; }