// Part of dump1090, a Mode S message decoder for RTLSDR devices. // // mode_s.c: Mode S message decoding. // // Copyright (c) 2014-2016 Oliver Jowett // // This file is free software: you may copy, redistribute and/or modify it // under the terms of the GNU General Public License as published by the // Free Software Foundation, either version 2 of the License, or (at your // option) any later version. // // This file 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, see . // This file incorporates work covered by the following copyright and // permission notice: // // Copyright (C) 2012 by Salvatore Sanfilippo // // All rights reserved. // // Redistribution and use in source and binary forms, with or without // modification, are permitted provided that the following conditions are // met: // // * Redistributions of source code must retain the above copyright // notice, this list of conditions and the following disclaimer. // // * Redistributions in binary form must reproduce the above copyright // notice, this list of conditions and the following disclaimer in the // documentation and/or other materials provided with the distribution. // // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT // HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. #include "dump1090.h" /* for PRIX64 */ #include #include // // ===================== Mode S detection and decoding =================== // // // /* A timestamp that indicates the data is synthetic, created from a * multilateration result */ #define MAGIC_MLAT_TIMESTAMP 0xFF004D4C4154ULL //========================================================================= // // Given the Downlink Format (DF) of the message, return the message length in bits. // // All known DF's 16 or greater are long. All known DF's 15 or less are short. // There are lots of unused codes in both category, so we can assume ICAO will stick to // these rules, meaning that the most significant bit of the DF indicates the length. // int modesMessageLenByType(int type) { return (type & 0x10) ? MODES_LONG_MSG_BITS : MODES_SHORT_MSG_BITS ; } // //========================================================================= // // In the squawk (identity) field bits are interleaved as follows in // (message bit 20 to bit 32): // // C1-A1-C2-A2-C4-A4-ZERO-B1-D1-B2-D2-B4-D4 // // So every group of three bits A, B, C, D represent an integer from 0 to 7. // // The actual meaning is just 4 octal numbers, but we convert it into a hex // number tha happens to represent the four octal numbers. // // For more info: http://en.wikipedia.org/wiki/Gillham_code // static int decodeID13Field(int ID13Field) { int hexGillham = 0; if (ID13Field & 0x1000) {hexGillham |= 0x0010;} // Bit 12 = C1 if (ID13Field & 0x0800) {hexGillham |= 0x1000;} // Bit 11 = A1 if (ID13Field & 0x0400) {hexGillham |= 0x0020;} // Bit 10 = C2 if (ID13Field & 0x0200) {hexGillham |= 0x2000;} // Bit 9 = A2 if (ID13Field & 0x0100) {hexGillham |= 0x0040;} // Bit 8 = C4 if (ID13Field & 0x0080) {hexGillham |= 0x4000;} // Bit 7 = A4 //if (ID13Field & 0x0040) {hexGillham |= 0x0800;} // Bit 6 = X or M if (ID13Field & 0x0020) {hexGillham |= 0x0100;} // Bit 5 = B1 if (ID13Field & 0x0010) {hexGillham |= 0x0001;} // Bit 4 = D1 or Q if (ID13Field & 0x0008) {hexGillham |= 0x0200;} // Bit 3 = B2 if (ID13Field & 0x0004) {hexGillham |= 0x0002;} // Bit 2 = D2 if (ID13Field & 0x0002) {hexGillham |= 0x0400;} // Bit 1 = B4 if (ID13Field & 0x0001) {hexGillham |= 0x0004;} // Bit 0 = D4 return (hexGillham); } // //========================================================================= // // Decode the 13 bit AC altitude field (in DF 20 and others). // Returns the altitude, and set 'unit' to either UNIT_METERS or UNIT_FEET. // static int decodeAC13Field(int AC13Field, altitude_unit_t *unit) { int m_bit = AC13Field & 0x0040; // set = meters, clear = feet int q_bit = AC13Field & 0x0010; // set = 25 ft encoding, clear = Gillham Mode C encoding if (!m_bit) { *unit = UNIT_FEET; if (q_bit) { // N is the 11 bit integer resulting from the removal of bit Q and M int n = ((AC13Field & 0x1F80) >> 2) | ((AC13Field & 0x0020) >> 1) | (AC13Field & 0x000F); // The final altitude is resulting number multiplied by 25, minus 1000. return ((n * 25) - 1000); } else { // N is an 11 bit Gillham coded altitude int n = ModeAToModeC(decodeID13Field(AC13Field)); if (n < -12) { return INVALID_ALTITUDE; } return (100 * n); } } else { *unit = UNIT_METERS; // TODO: Implement altitude when meter unit is selected return INVALID_ALTITUDE; } } // //========================================================================= // // Decode the 12 bit AC altitude field (in DF 17 and others). // static int decodeAC12Field(int AC12Field, altitude_unit_t *unit) { int q_bit = AC12Field & 0x10; // Bit 48 = Q *unit = UNIT_FEET; if (q_bit) { /// N is the 11 bit integer resulting from the removal of bit Q at bit 4 int n = ((AC12Field & 0x0FE0) >> 1) | (AC12Field & 0x000F); // The final altitude is the resulting number multiplied by 25, minus 1000. return ((n * 25) - 1000); } else { // Make N a 13 bit Gillham coded altitude by inserting M=0 at bit 6 int n = ((AC12Field & 0x0FC0) << 1) | (AC12Field & 0x003F); n = ModeAToModeC(decodeID13Field(n)); if (n < -12) { return INVALID_ALTITUDE; } return (100 * n); } } // //========================================================================= // // Decode the 7 bit ground movement field PWL exponential style scale // static unsigned decodeMovementField(unsigned movement) { int gspeed; // Note : movement codes 0,125,126,127 are all invalid, but they are // trapped for before this function is called. if (movement > 123) gspeed = 199; // > 175kt else if (movement > 108) gspeed = ((movement - 108) * 5) + 100; else if (movement > 93) gspeed = ((movement - 93) * 2) + 70; else if (movement > 38) gspeed = ((movement - 38) ) + 15; else if (movement > 12) gspeed = ((movement - 11) >> 1) + 2; else if (movement > 8) gspeed = ((movement - 6) >> 2) + 1; else gspeed = 0; return (gspeed); } // Correct a decoded native-endian Address Announced field // (from bits 8-31) if it is affected by the given error // syndrome. Updates *addr and returns >0 if changed, 0 if // it was unaffected. static int correct_aa_field(uint32_t *addr, struct errorinfo *ei) { int i; int addr_errors = 0; if (!ei) return 0; for (i = 0; i < ei->errors; ++i) { if (ei->bit[i] >= 8 && ei->bit[i] <= 31) { *addr ^= 1 << (31 - ei->bit[i]); ++addr_errors; } } return addr_errors; } // The first bit (MSB of the first byte) is numbered 1, for consistency // with how the specs number them. // Extract one bit from a message. static inline __attribute__((always_inline)) unsigned getbit(unsigned char *data, unsigned bitnum) { unsigned bi = bitnum - 1; unsigned by = bi >> 3; unsigned mask = 1 << (7 - (bi & 7)); return (data[by] & mask) != 0; } // Extract some bits (firstbit .. lastbit inclusive) from a message. static inline __attribute__((always_inline)) unsigned getbits(unsigned char *data, unsigned firstbit, unsigned lastbit) { unsigned fbi = firstbit - 1; unsigned lbi = lastbit - 1; unsigned nbi = (lastbit - firstbit + 1); unsigned fby = fbi >> 3; unsigned lby = lbi >> 3; unsigned nby = (lby - fby) + 1; unsigned shift = 7 - (lbi & 7); unsigned topmask = 0xFF >> (fbi & 7); assert (fbi <= lbi); assert (nbi <= 32); assert (nby <= 5); if (nby == 5) { return ((data[fby] & topmask) << (32 - shift)) | (data[fby + 1] << (24 - shift)) | (data[fby + 2] << (16 - shift)) | (data[fby + 3] << (8 - shift)) | (data[fby + 4] >> shift); } else if (nby == 4) { return ((data[fby] & topmask) << (24 - shift)) | (data[fby + 1] << (16 - shift)) | (data[fby + 2] << (8 - shift)) | (data[fby + 3] >> shift); } else if (nby == 3) { return ((data[fby] & topmask) << (16 - shift)) | (data[fby + 1] << (8 - shift)) | (data[fby + 2] >> shift); } else if (nby == 2) { return ((data[fby] & topmask) << (8 - shift)) | (data[fby + 1] >> shift); } else if (nby == 1) { return (data[fby] & topmask) >> shift; } else { return 0; } } // Score how plausible this ModeS message looks. // The more positive, the more reliable the message is // 1000: DF 0/4/5/16/24 with a CRC-derived address matching a known aircraft // 1800: DF17/18 with good CRC and an address matching a known aircraft // 1400: DF17/18 with good CRC and an address not matching a known aircraft // 900: DF17/18 with 1-bit error and an address matching a known aircraft // 700: DF17/18 with 1-bit error and an address not matching a known aircraft // 450: DF17/18 with 2-bit error and an address matching a known aircraft // 350: DF17/18 with 2-bit error and an address not matching a known aircraft // 1600: DF11 with IID==0, good CRC and an address matching a known aircraft // 800: DF11 with IID==0, 1-bit error and an address matching a known aircraft // 750: DF11 with IID==0, good CRC and an address not matching a known aircraft // 375: DF11 with IID==0, 1-bit error and an address not matching a known aircraft // 1000: DF11 with IID!=0, good CRC and an address matching a known aircraft // 500: DF11 with IID!=0, 1-bit error and an address matching a known aircraft // 1000: DF20/21 with a CRC-derived address matching a known aircraft // 500: DF20/21 with a CRC-derived address matching a known aircraft (bottom 16 bits only - overlay control in use) // -1: message might be valid, but we couldn't validate the CRC against a known ICAO // -2: bad message or unrepairable CRC error static unsigned char all_zeros[14] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }; int scoreModesMessage(unsigned char *msg, int validbits) { int msgtype, msgbits, crc, iid; uint32_t addr; struct errorinfo *ei; if (validbits < 56) return -2; msgtype = getbits(msg, 1, 5); // Downlink Format msgbits = modesMessageLenByType(msgtype); if (validbits < msgbits) return -2; if (!memcmp(all_zeros, msg, msgbits/8)) return -2; crc = modesChecksum(msg, msgbits); switch (msgtype) { case 0: // short air-air surveillance case 4: // surveillance, altitude reply case 5: // surveillance, altitude reply case 16: // long air-air surveillance case 24: // Comm-D (ELM) case 25: // Comm-D (ELM) case 26: // Comm-D (ELM) case 27: // Comm-D (ELM) case 28: // Comm-D (ELM) case 29: // Comm-D (ELM) case 30: // Comm-D (ELM) case 31: // Comm-D (ELM) return icaoFilterTest(crc) ? 1000 : -1; case 11: // All-call reply iid = crc & 0x7f; crc = crc & 0xffff80; addr = getbits(msg, 9, 32); ei = modesChecksumDiagnose(crc, msgbits); if (!ei) return -2; // can't correct errors // see crc.c comments: we do not attempt to fix // more than single-bit errors, as two-bit // errors are ambiguous in DF11. if (ei->errors > 1) return -2; // can't correct errors // fix any errors in the address field correct_aa_field(&addr, ei); // validate address if (iid == 0) { if (icaoFilterTest(addr)) return 1600 / (ei->errors + 1); else return 750 / (ei->errors + 1); } else { if (icaoFilterTest(addr)) return 1000 / (ei->errors + 1); else return -1; } case 17: // Extended squitter case 18: // Extended squitter/non-transponder ei = modesChecksumDiagnose(crc, msgbits); if (!ei) return -2; // can't correct errors // fix any errors in the address field addr = getbits(msg, 9, 32); correct_aa_field(&addr, ei); if (icaoFilterTest(addr)) return 1800 / (ei->errors+1); else return 1400 / (ei->errors+1); case 20: // Comm-B, altitude reply case 21: // Comm-B, identity reply if (icaoFilterTest(crc)) return 1000; // Address/Parity #if 0 // This doesn't seem useful, as we mistake a lot of CRC errors // for overlay control if (icaoFilterTestFuzzy(crc)) return 500; // Data/Parity #endif return -2; default: // unknown message type return -2; } } // //========================================================================= // // Decode a raw Mode S message demodulated as a stream of bytes by detectModeS(), // and split it into fields populating a modesMessage structure. // static void decodeExtendedSquitter(struct modesMessage *mm); static void decodeCommB(struct modesMessage *mm); static char *ais_charset = "@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_ !\"#$%&'()*+,-./0123456789:;<=>?"; // return 0 if all OK // -1: message might be valid, but we couldn't validate the CRC against a known ICAO // -2: bad message or unrepairable CRC error int decodeModesMessage(struct modesMessage *mm, unsigned char *msg) { // Work on our local copy. memcpy(mm->msg, msg, MODES_LONG_MSG_BYTES); if (Modes.net_verbatim) { // Preserve the original uncorrected copy for later forwarding memcpy(mm->verbatim, msg, MODES_LONG_MSG_BYTES); } msg = mm->msg; // don't accept all-zeros messages if (!memcmp(all_zeros, msg, 7)) return -2; // Get the message type ASAP as other operations depend on this mm->msgtype = getbits(msg, 1, 5); // Downlink Format mm->msgbits = modesMessageLenByType(mm->msgtype); mm->crc = modesChecksum(msg, mm->msgbits); mm->correctedbits = 0; mm->addr = 0; // Do checksum work and set fields that depend on the CRC switch (mm->msgtype) { case 0: // short air-air surveillance case 4: // surveillance, altitude reply case 5: // surveillance, altitude reply case 16: // long air-air surveillance case 24: // Comm-D (ELM) case 25: // Comm-D (ELM) case 26: // Comm-D (ELM) case 27: // Comm-D (ELM) case 28: // Comm-D (ELM) case 29: // Comm-D (ELM) case 30: // Comm-D (ELM) case 31: // Comm-D (ELM) // These message types use Address/Parity, i.e. our CRC syndrome is the sender's ICAO address. // We can't tell if the CRC is correct or not as we don't know the correct address. // Accept the message if it appears to be from a previously-seen aircraft if (!icaoFilterTest(mm->crc)) { return -1; } mm->source = SOURCE_MODE_S; mm->addr = mm->crc; break; case 11: // All-call reply // This message type uses Parity/Interrogator, i.e. our CRC syndrome is CL + IC from the uplink message // which we can't see. So we don't know if the CRC is correct or not. // // however! CL + IC only occupy the lower 7 bits of the CRC. So if we ignore those bits when testing // the CRC we can still try to detect/correct errors. mm->IID = mm->crc & 0x7f; if (mm->crc & 0xffff80) { int addr; struct errorinfo *ei = modesChecksumDiagnose(mm->crc & 0xffff80, mm->msgbits); if (!ei) { return -2; // couldn't fix it } // see crc.c comments: we do not attempt to fix // more than single-bit errors, as two-bit // errors are ambiguous in DF11. if (ei->errors > 1) return -2; // can't correct errors mm->correctedbits = ei->errors; modesChecksumFix(msg, ei); // check whether the corrected message looks sensible // we are conservative here: only accept corrected messages that // match an existing aircraft. addr = getbits(msg, 9, 32); if (!icaoFilterTest(addr)) { return -1; } } mm->source = SOURCE_MODE_S_CHECKED; break; case 17: // Extended squitter case 18: { // Extended squitter/non-transponder struct errorinfo *ei; int addr1, addr2; // These message types use Parity/Interrogator, but are specified to set II=0 if (mm->crc != 0) { ei = modesChecksumDiagnose(mm->crc, mm->msgbits); if (!ei) { return -2; // couldn't fix it } addr1 = getbits(msg, 9, 32); mm->correctedbits = ei->errors; modesChecksumFix(msg, ei); addr2 = getbits(msg, 9, 32); // we are conservative here: only accept corrected messages that // match an existing aircraft. if (addr1 != addr2 && !icaoFilterTest(addr2)) { return -1; } } mm->source = SOURCE_ADSB; // TIS-B decoding will override this if needed break; } case 20: // Comm-B, altitude reply case 21: // Comm-B, identity reply // These message types either use Address/Parity (see DF0 etc) // or Data Parity where the requested BDS is also xored into the top byte. // So not only do we not know whether the CRC is right, we also don't know if // the ICAO is right! Ow. // Try an exact match if (icaoFilterTest(mm->crc)) { // OK. mm->source = SOURCE_MODE_S; mm->addr = mm->crc; break; } // BDS / overlay control just doesn't work out. return -1; // no good default: // All other message types, we don't know how to handle their CRCs, give up return -2; } // decode the bulk of the message // AA (Address announced) if (mm->msgtype == 11 || mm->msgtype == 17 || mm->msgtype == 18) { mm->AA = mm->addr = getbits(msg, 9, 32); } // AC (Altitude Code) if (mm->msgtype == 0 || mm->msgtype == 4 || mm->msgtype == 16 || mm->msgtype == 20) { mm->AC = getbits(msg, 20, 32); if (mm->AC) { // Only attempt to decode if a valid (non zero) altitude is present mm->altitude = decodeAC13Field(mm->AC, &mm->altitude_unit); if (mm->altitude != INVALID_ALTITUDE) mm->altitude_valid = 1; mm->altitude_source = ALTITUDE_BARO; } } // AF (DF19 Application Field) not decoded // CA (Capability) if (mm->msgtype == 11 || mm->msgtype == 17) { mm->CA = getbits(msg, 6, 8); switch (mm->CA) { case 0: mm->airground = AG_UNCERTAIN; break; case 4: mm->airground = AG_GROUND; break; case 5: mm->airground = AG_AIRBORNE; break; case 6: mm->airground = AG_UNCERTAIN; break; case 7: mm->airground = AG_UNCERTAIN; break; } } // CC (Cross-link capability) if (mm->msgtype == 0) { mm->CC = getbit(msg, 7); } // CF (Control field) if (mm->msgtype == 18) { mm->CF = getbits(msg, 5, 8); } // DR (Downlink Request) if (mm->msgtype == 4 || mm->msgtype == 5 || mm->msgtype == 20 || mm->msgtype == 21) { mm->DR = getbits(msg, 9, 13); } // FS (Flight Status) if (mm->msgtype == 4 || mm->msgtype == 5 || mm->msgtype == 20 || mm->msgtype == 21) { mm->FS = getbits(msg, 6, 8); mm->alert_valid = 1; mm->spi_valid = 1; switch (mm->FS) { case 0: mm->airground = AG_UNCERTAIN; break; case 1: mm->airground = AG_GROUND; break; case 2: mm->airground = AG_UNCERTAIN; mm->alert = 1; break; case 3: mm->airground = AG_GROUND; mm->alert = 1; break; case 4: mm->airground = AG_UNCERTAIN; mm->alert = 1; mm->spi = 1; break; case 5: mm->airground = AG_UNCERTAIN; mm->spi = 1; break; default: mm->spi_valid = 0; mm->alert_valid = 0; break; } } // ID (Identity) if (mm->msgtype == 5 || mm->msgtype == 21) { // Gillham encoded Squawk mm->ID = getbits(msg, 20, 32); if (mm->ID) { mm->squawk = decodeID13Field(mm->ID); mm->squawk_valid = 1; } } // KE (Control, ELM) if (mm->msgtype >= 24 && mm->msgtype <= 31) { mm->KE = getbit(msg, 4); } // MB (messsage, Comm-B) if (mm->msgtype == 20 || mm->msgtype == 21) { memcpy(mm->MB, &msg[4], 7); decodeCommB(mm); } // MD (message, Comm-D) if (mm->msgtype >= 24 && mm->msgtype <= 31) { memcpy(mm->MD, &msg[1], 10); } // ME (message, extended squitter) if (mm->msgtype == 17 || mm->msgtype == 18) { memcpy(mm->ME, &msg[4], 7); decodeExtendedSquitter(mm); } // MV (message, ACAS) if (mm->msgtype == 16) { memcpy(mm->MV, &msg[4], 7); } // ND (number of D-segment, Comm-D) if (mm->msgtype >= 24 && mm->msgtype <= 31) { mm->ND = getbits(msg, 5, 8); } // RI (Reply information, ACAS) if (mm->msgtype == 0 || mm->msgtype == 16) { mm->RI = getbits(msg, 14, 17); } // SL (Sensitivity level, ACAS) if (mm->msgtype == 0 || mm->msgtype == 16) { mm->SL = getbits(msg, 9, 11); } // UM (Utility Message) if (mm->msgtype == 4 || mm->msgtype == 5 || mm->msgtype == 20 || mm->msgtype == 21) { mm->UM = getbits(msg, 14, 19); } // VS (Vertical Status) if (mm->msgtype == 0 || mm->msgtype == 16) { mm->VS = getbit(msg, 6); if (mm->VS) mm->airground = AG_GROUND; else mm->airground = AG_UNCERTAIN; } if (!mm->correctedbits && (mm->msgtype == 17 || mm->msgtype == 18 || (mm->msgtype == 11 && mm->IID == 0))) { // No CRC errors seen, and either it was an DF17/18 extended squitter // or a DF11 acquisition squitter with II = 0. We probably have the right address. // We wait until here to do this as we may have needed to decode an ES to note // the type of address in DF18 messages. // NB this is the only place that adds addresses! icaoFilterAdd(mm->addr); } // MLAT overrides all other sources if (mm->remote && mm->timestampMsg == MAGIC_MLAT_TIMESTAMP) mm->source = SOURCE_MLAT; // all done return 0; } // Decode BDS2,0 carried in Comm-B or ES static void decodeBDS20(struct modesMessage *mm) { unsigned char *msg = mm->msg; mm->callsign[0] = ais_charset[getbits(msg, 41, 46)]; mm->callsign[1] = ais_charset[getbits(msg, 47, 52)]; mm->callsign[2] = ais_charset[getbits(msg, 53, 58)]; mm->callsign[3] = ais_charset[getbits(msg, 59, 64)]; mm->callsign[4] = ais_charset[getbits(msg, 65, 70)]; mm->callsign[5] = ais_charset[getbits(msg, 71, 76)]; mm->callsign[6] = ais_charset[getbits(msg, 77, 82)]; mm->callsign[7] = ais_charset[getbits(msg, 83, 88)]; mm->callsign[8] = 0; // Catch possible bad decodings since BDS2,0 is not // 100% reliable: accept only alphanumeric data mm->callsign_valid = 1; for (int i = 0; i < 8; ++i) { if (! ((mm->callsign[i] >= 'A' && mm->callsign[i] <= 'Z') || (mm->callsign[i] >= '0' && mm->callsign[i] <= '9') || mm->callsign[i] == ' ') ) { mm->callsign_valid = 0; break; } } } static void decodeESIdentAndCategory(struct modesMessage *mm) { // Aircraft Identification and Category unsigned char *me = mm->ME; mm->mesub = getbits(me, 6, 8); mm->callsign[0] = ais_charset[getbits(me, 9, 14)]; mm->callsign[1] = ais_charset[getbits(me, 15, 20)]; mm->callsign[2] = ais_charset[getbits(me, 21, 26)]; mm->callsign[3] = ais_charset[getbits(me, 27, 32)]; mm->callsign[4] = ais_charset[getbits(me, 33, 38)]; mm->callsign[5] = ais_charset[getbits(me, 39, 44)]; mm->callsign[6] = ais_charset[getbits(me, 45, 50)]; mm->callsign[7] = ais_charset[getbits(me, 51, 56)]; // A common failure mode seems to be to intermittently send // all zeros. Catch that here. mm->callsign_valid = (strcmp(mm->callsign, "@@@@@@@@") != 0); mm->category = ((0x0E - mm->metype) << 4) | mm->mesub; mm->category_valid = 1; } static void decodeESAirborneVelocity(struct modesMessage *mm, int check_imf) { // Airborne Velocity Message unsigned char *me = mm->ME; mm->mesub = getbits(me, 6, 8); if (check_imf && getbit(me, 9)) mm->addr |= MODES_NON_ICAO_ADDRESS; if (mm->mesub < 1 || mm->mesub > 4) return; unsigned vert_rate = getbits(me, 38, 46); if (vert_rate) { mm->vert_rate = (vert_rate - 1) * (getbit(me, 37) ? -64 : 64); mm->vert_rate_valid = 1; } mm->vert_rate_source = (getbit(me, 36) ? ALTITUDE_GNSS : ALTITUDE_BARO); switch (mm->mesub) { case 1: case 2: { unsigned ew_raw = getbits(me, 15, 24); unsigned ns_raw = getbits(me, 26, 35); if (ew_raw && ns_raw) { int ew_vel = (ew_raw - 1) * (getbit(me, 14) ? -1 : 1) * ((mm->mesub == 2) ? 4 : 1); int ns_vel = (ns_raw - 1) * (getbit(me, 25) ? -1 : 1) * ((mm->mesub == 2) ? 4 : 1); // Compute velocity and angle from the two speed components mm->speed = (unsigned) sqrt((ns_vel * ns_vel) + (ew_vel * ew_vel) + 0.5); mm->speed_valid = 1; if (mm->speed) { int heading = (int) (atan2(ew_vel, ns_vel) * 180.0 / M_PI + 0.5); // We don't want negative values but a 0-360 scale if (heading < 0) heading += 360; mm->heading = (unsigned) heading; mm->heading_source = HEADING_TRUE; mm->heading_valid = 1; } mm->speed_source = SPEED_GROUNDSPEED; } break; } case 3: case 4: { unsigned airspeed = getbits(me, 26, 35); if (airspeed) { mm->speed = (airspeed - 1) * (mm->mesub == 4 ? 4 : 1); mm->speed_source = getbit(me, 25) ? SPEED_TAS : SPEED_IAS; mm->speed_valid = 1; } if (getbit(me, 14)) { mm->heading = getbits(me, 15, 24); mm->heading_source = HEADING_MAGNETIC; mm->heading_valid = 1; } break; } } unsigned raw_delta = getbits(me, 50, 56); if (raw_delta) { mm->gnss_delta_valid = 1; mm->gnss_delta = (raw_delta - 1) * (getbit(me, 49) ? -25 : 25); } } static void decodeESSurfacePosition(struct modesMessage *mm, int check_imf) { // Surface position and movement unsigned char *me = mm->ME; if (check_imf && getbit(me, 21)) mm->addr |= MODES_NON_ICAO_ADDRESS; mm->airground = AG_GROUND; // definitely. mm->cpr_lat = getbits(me, 23, 39); mm->cpr_lon = getbits(me, 40, 56); mm->cpr_odd = getbit(me, 22); mm->cpr_nucp = (14 - mm->metype); mm->cpr_valid = 1; unsigned movement = getbits(me, 6, 12); if (movement > 0 && movement < 125) { mm->speed_valid = 1; mm->speed = decodeMovementField(movement); mm->speed_source = SPEED_GROUNDSPEED; } if (getbit(me, 13)) { mm->heading_valid = 1; mm->heading_source = HEADING_TRUE; mm->heading = getbits(me, 14, 20) * 360 / 128; } } static void decodeESAirbornePosition(struct modesMessage *mm, int check_imf) { // Airborne position and altitude unsigned char *me = mm->ME; if (check_imf && getbit(me, 8)) mm->addr |= MODES_NON_ICAO_ADDRESS; unsigned AC12Field = getbits(me, 9, 20); if (mm->metype == 0) { mm->cpr_nucp = 0; } else { // Catch some common failure modes and don't mark them as valid // (so they won't be used for positioning) mm->cpr_lat = getbits(me, 23, 39); mm->cpr_lon = getbits(me, 40, 56); if (AC12Field == 0 && mm->cpr_lon == 0 && (mm->cpr_lat & 0x0fff) == 0 && mm->metype == 15) { // Seen from at least: // 400F3F (Eurocopter ECC155 B1) - Bristow Helicopters // 4008F3 (BAE ATP) - Atlantic Airlines // 400648 (BAE ATP) - Atlantic Airlines // altitude == 0, longitude == 0, type == 15 and zeros in latitude LSB. // Can alternate with valid reports having type == 14 Modes.stats_current.cpr_filtered++; } else { // Otherwise, assume it's valid. mm->cpr_valid = 1; mm->cpr_odd = getbit(me, 22); if (mm->metype == 18 || mm->metype == 22) mm->cpr_nucp = 0; else if (mm->metype < 18) mm->cpr_nucp = (18 - mm->metype); else mm->cpr_nucp = (29 - mm->metype); } } if (AC12Field) {// Only attempt to decode if a valid (non zero) altitude is present mm->altitude = decodeAC12Field(AC12Field, &mm->altitude_unit); if (mm->altitude != INVALID_ALTITUDE) { mm->altitude_valid = 1; } mm->altitude_source = (mm->metype == 20 || mm->metype == 21 || mm->metype == 22) ? ALTITUDE_GNSS : ALTITUDE_BARO; } } static void decodeESTestMessage(struct modesMessage *mm) { unsigned char *me = mm->ME; mm->mesub = getbits(me, 6, 8); if (mm->mesub == 7) { // (see 1090-WP-15-20) int ID13Field = getbits(me, 9, 21); if (ID13Field) { mm->squawk_valid = 1; mm->squawk = decodeID13Field(ID13Field); } } } static void decodeESAircraftStatus(struct modesMessage *mm, int check_imf) { // Extended Squitter Aircraft Status unsigned char *me = mm->ME; mm->mesub = getbits(me, 6, 8); if (mm->mesub == 1) { // Emergency status squawk field int ID13Field = getbits(me, 12, 24); if (ID13Field) { mm->squawk_valid = 1; mm->squawk = decodeID13Field(ID13Field); } if (check_imf && getbit(me, 56)) mm->addr |= MODES_NON_ICAO_ADDRESS; } } static void decodeESTargetStatus(struct modesMessage *mm, int check_imf) { unsigned char *me = mm->ME; mm->mesub = getbits(me, 6, 7); // an unusual message: only 2 bits of subtype if (check_imf && getbit(me, 51)) mm->addr |= MODES_NON_ICAO_ADDRESS; if (mm->mesub == 0) { // Target state and status, V1 // TODO: need RTCA/DO-260A } else if (mm->mesub == 1) { // Target state and status, V2 mm->tss.valid = 1; mm->tss.sil_type = getbit(me, 8) ? SIL_PER_SAMPLE : SIL_PER_HOUR; mm->tss.altitude_type = getbit(me, 9) ? TSS_ALTITUDE_FMS : TSS_ALTITUDE_MCP; unsigned alt_bits = getbits(me, 10, 20); if (alt_bits == 0) { mm->tss.altitude_valid = 0; } else { mm->tss.altitude_valid = 1; mm->tss.altitude = (alt_bits - 1) * 32; } unsigned baro_bits = getbits(me, 21, 29); if (baro_bits == 0) { mm->tss.baro_valid = 0; } else { mm->tss.baro_valid = 1; mm->tss.baro = 800.0 + (baro_bits - 1) * 0.8; } mm->tss.heading_valid = getbit(me, 30); if (mm->tss.heading_valid) { // two's complement -180..+180, which is conveniently // also the same as unsigned 0..360 mm->tss.heading = getbits(me, 31, 39) * 180 / 256; } mm->tss.nac_p = getbits(me, 40, 43); mm->tss.nic_baro = getbit(me, 44); mm->tss.sil = getbits(me, 45, 46); mm->tss.mode_valid = getbit(me, 47); if (mm->tss.mode_valid) { mm->tss.mode_autopilot = getbit(me, 48); mm->tss.mode_vnav = getbit(me, 49); mm->tss.mode_alt_hold = getbit(me, 50); mm->tss.mode_approach = getbit(me, 52); } mm->tss.acas_operational = getbit(me, 53); } } static void decodeESOperationalStatus(struct modesMessage *mm, int check_imf) { unsigned char *me = mm->ME; mm->mesub = getbits(me, 6, 8); // Aircraft Operational Status if (check_imf && getbit(me, 56)) mm->addr |= MODES_NON_ICAO_ADDRESS; if (mm->mesub == 0 || mm->mesub == 1) { mm->opstatus.valid = 1; mm->opstatus.version = getbits(me, 41, 43); switch (mm->opstatus.version) { case 0: break; case 1: if (getbits(me, 25, 26) == 0) { mm->opstatus.om_acas_ra = getbit(me, 27); mm->opstatus.om_ident = getbit(me, 28); mm->opstatus.om_atc = getbit(me, 29); } if (mm->mesub == 0 && getbits(me, 9, 10) == 0 && getbits(me, 13, 14) == 0) { // airborne mm->opstatus.cc_acas = !getbit(me, 11); mm->opstatus.cc_cdti = getbit(me, 12); mm->opstatus.cc_arv = getbit(me, 15); mm->opstatus.cc_ts = getbit(me, 16); mm->opstatus.cc_tc = getbits(me, 17, 18); } else if (mm->mesub == 1 && getbits(me, 9, 10) == 0 && getbits(me, 13, 14) == 0) { // surface mm->opstatus.cc_poa = getbit(me, 11); mm->opstatus.cc_cdti = getbit(me, 12); mm->opstatus.cc_b2_low = getbit(me, 15); mm->opstatus.cc_lw_valid = 1; mm->opstatus.cc_lw = getbits(me, 21, 24); } mm->opstatus.nic_supp_a = getbit(me, 44); mm->opstatus.nac_p = getbits(me, 45, 48); mm->opstatus.sil = getbits(me, 51, 52); if (mm->mesub == 0) { mm->opstatus.nic_baro = getbit(me, 53); } else { mm->opstatus.track_angle = getbit(me, 53) ? ANGLE_TRACK : ANGLE_HEADING; } mm->opstatus.hrd = getbit(me, 54) ? HEADING_MAGNETIC : HEADING_TRUE; break; case 2: default: if (getbits(me, 25, 26) == 0) { mm->opstatus.om_acas_ra = getbit(me, 27); mm->opstatus.om_ident = getbit(me, 28); mm->opstatus.om_atc = getbit(me, 29); mm->opstatus.om_saf = getbit(me, 30); mm->opstatus.om_sda = getbits(me, 31, 32); } if (mm->mesub == 0 && getbits(me, 9, 10) == 0 && getbits(me, 13, 14) == 0) { // airborne mm->opstatus.cc_acas = getbit(me, 11); mm->opstatus.cc_1090_in = getbit(me, 12); mm->opstatus.cc_arv = getbit(me, 15); mm->opstatus.cc_ts = getbit(me, 16); mm->opstatus.cc_tc = getbits(me, 17, 18); mm->opstatus.cc_uat_in = getbit(me, 19); } else if (mm->mesub == 1 && getbits(me, 9, 10) == 0 && getbits(me, 13, 14) == 0) { // surface mm->opstatus.cc_poa = getbit(me, 11); mm->opstatus.cc_1090_in = getbit(me, 12); mm->opstatus.cc_b2_low = getbit(me, 15); mm->opstatus.cc_uat_in = getbit(me, 16); mm->opstatus.cc_nac_v = getbits(me, 17, 19); mm->opstatus.cc_nic_supp_c = getbit(me, 20); mm->opstatus.cc_lw_valid = 1; mm->opstatus.cc_lw = getbits(me, 21, 24); mm->opstatus.cc_antenna_offset = getbits(me, 33, 40); } mm->opstatus.nic_supp_a = getbit(me, 44); mm->opstatus.nac_p = getbits(me, 45, 48); mm->opstatus.sil = getbits(me, 51, 52); if (mm->mesub == 0) { mm->opstatus.gva = getbits(me, 49, 50); mm->opstatus.nic_baro = getbit(me, 53); } else { mm->opstatus.track_angle = getbit(me, 53) ? ANGLE_TRACK : ANGLE_HEADING; } mm->opstatus.hrd = getbit(me, 54) ? HEADING_MAGNETIC : HEADING_TRUE; mm->opstatus.sil_type = getbit(me, 55) ? SIL_PER_SAMPLE : SIL_PER_HOUR; break; } } } static void decodeExtendedSquitter(struct modesMessage *mm) { unsigned char *me = mm->ME; unsigned metype = mm->metype = getbits(me, 1, 5); unsigned check_imf = 0; // Check CF on DF18 to work out the format of the ES and whether we need to look for an IMF bit if (mm->msgtype == 18) { switch (mm->CF) { case 0: // ADS-B ES/NT devices that report the ICAO 24-bit address in the AA field break; case 1: // Reserved for ADS-B for ES/NT devices that use other addressing techniques in the AA field mm->addr |= MODES_NON_ICAO_ADDRESS; break; case 2: // Fine TIS-B message (formats are close enough to DF17 for our purposes) mm->source = SOURCE_TISB; check_imf = 1; break; case 3: // Coarse TIS-B airborne position and velocity. // TODO: decode me. // For now we only look at the IMF bit. mm->source = SOURCE_TISB; if (getbit(me, 1)) mm->addr |= MODES_NON_ICAO_ADDRESS; return; case 5: // TIS-B messages that relay ADS-B Messages using anonymous 24-bit addresses (format not explicitly defined, but it seems to follow DF17) mm->source = SOURCE_TISB; mm->addr |= MODES_NON_ICAO_ADDRESS; break; case 6: // ADS-B rebroadcast using the same type codes and message formats as defined for DF = 17 ADS-B messages check_imf = 1; break; default: // All others, we don't know the format. mm->addr |= MODES_NON_ICAO_ADDRESS; // assume non-ICAO return; } } switch (metype) { case 1: case 2: case 3: case 4: decodeESIdentAndCategory(mm); break; case 19: decodeESAirborneVelocity(mm, check_imf); break; case 5: case 6: case 7: case 8: decodeESSurfacePosition(mm, check_imf); break; case 0: // Airborne position, baro altitude only case 9: case 10: case 11: case 12: case 13: case 14: case 15: case 16: case 17: case 18: // Airborne position, baro case 20: case 21: case 22: // Airborne position, GNSS altitude (HAE or MSL) decodeESAirbornePosition(mm, check_imf); break; case 23: decodeESTestMessage(mm); break; case 24: // Reserved for Surface System Status break; case 28: decodeESAircraftStatus(mm, check_imf); break; case 29: decodeESTargetStatus(mm, check_imf); break; case 30: // Aircraft Operational Coordination break; case 31: decodeESOperationalStatus(mm, check_imf); break; default: break; } } static void decodeCommB(struct modesMessage *mm) { unsigned char *msg = mm->msg; // This is a bit hairy as we don't know what the requested register was if (getbits(msg, 33, 40) == 0x20) { // BDS 2,0 Aircraft Identification decodeBDS20(mm); } } static const char *df_names[33] = { /* 0 */ "Short Air-Air Surveillance", /* 1 */ NULL, /* 2 */ NULL, /* 3 */ NULL, /* 4 */ "Survelliance, Altitude Reply", /* 5 */ "Survelliance, Identity Reply", /* 6 */ NULL, /* 7 */ NULL, /* 8 */ NULL, /* 9 */ NULL, /* 10 */ NULL, /* 11 */ "All Call Reply", /* 12 */ NULL, /* 13 */ NULL, /* 14 */ NULL, /* 15 */ NULL, /* 16 */ "Long Air-Air ACAS", /* 17 */ "Extended Squitter", /* 18 */ "Extended Squitter (Non-Transponder)", /* 19 */ "Extended Squitter (Military)", /* 20 */ "Comm-B, Altitude Reply", /* 21 */ "Comm-B, Identity Reply", /* 22 */ "Military Use", /* 23 */ NULL, /* 24 */ "Comm-D Extended Length Message", /* 25 */ "Comm-D Extended Length Message", /* 26 */ "Comm-D Extended Length Message", /* 27 */ "Comm-D Extended Length Message", /* 28 */ "Comm-D Extended Length Message", /* 29 */ "Comm-D Extended Length Message", /* 30 */ "Comm-D Extended Length Message", /* 31 */ "Comm-D Extended Length Message", /* 32 */ "Mode A/C Reply", }; static const char *df_to_string(unsigned df) { if (df > 32) return "out of range"; if (!df_names[df]) return "reserved"; return df_names[df]; } static const char *altitude_unit_to_string(altitude_unit_t unit) { switch (unit) { case UNIT_FEET: return "ft"; case UNIT_METERS: return "m"; default: return "(unknown altitude unit)"; } } static const char *altitude_source_to_string(altitude_source_t source) { switch (source) { case ALTITUDE_BARO: return "barometric"; case ALTITUDE_GNSS: return "GNSS"; default: return "(unknown altitude source)"; } } static const char *airground_to_string(airground_t airground) { switch (airground) { case AG_GROUND: return "ground"; case AG_AIRBORNE: return "airborne"; case AG_INVALID: return "invalid"; case AG_UNCERTAIN: return "airborne?"; default: return "(unknown airground state)"; } } static const char *speed_source_to_string(speed_source_t speed) { switch (speed) { case SPEED_GROUNDSPEED: return "groundspeed"; case SPEED_IAS: return "IAS"; case SPEED_TAS: return "TAS"; default: return "(unknown speed type)"; } } static void print_hex_bytes(unsigned char *data, size_t len) { size_t i; for (i = 0; i < len; ++i) { printf("%02X", (unsigned)data[i]); } } static int esTypeHasSubtype(unsigned metype) { if (metype <= 18) { return 0; } if (metype >= 20 && metype <= 22) { return 0; } return 1; } static const char *esTypeName(unsigned metype, unsigned mesub) { switch (metype) { case 0: return "No position information (airborne or surface)"; case 1: case 2: case 3: case 4: return "Aircraft identification and category"; case 5: case 6: case 7: case 8: return "Surface position"; case 9: case 10: case 11: case 12: case 13: case 14: case 15: case 16: case 17: case 18: return "Airborne position (barometric altitude)"; case 19: switch (mesub) { case 1: return "Airborne velocity over ground, subsonic"; case 2: return "Airborne velocity over ground, supersonic"; case 3: return "Airspeed and heading, subsonic"; case 4: return "Airspeed and heading, supersonic"; default: return "Unknown"; } case 20: case 21: case 22: return "Airborne position (GNSS altitude)"; case 23: switch (mesub) { case 0: return "Test message"; case 7: return "National use / 1090-WP-15-20 Mode A squawk"; default: return "Unknown"; } case 24: return "Reserved for surface system status"; case 27: return "Reserved for trajectory change"; case 28: switch (mesub) { case 1: return "Emergency/priority status"; case 2: return "ACAS RA broadcast"; default: return "Unknown"; } case 29: switch (mesub) { case 1: return "Target state and status"; default: return "Unknown"; } case 31: // Aircraft Operational Status switch (mesub) { case 0: return "Aircraft operational status (airborne)"; case 1: return "Aircraft operational status (surface)"; default: return "Unknown"; } default: return "Unknown"; } } void displayModesMessage(struct modesMessage *mm) { int j; // Handle only addresses mode first. if (Modes.onlyaddr) { printf("%06x\n", mm->addr); return; // Enough for --onlyaddr mode } // Show the raw message. if (Modes.mlat && mm->timestampMsg) { printf("@%012" PRIX64, mm->timestampMsg); } else printf("*"); for (j = 0; j < mm->msgbits/8; j++) printf("%02x", mm->msg[j]); printf(";\n"); if (Modes.raw) { fflush(stdout); // Provide data to the reader ASAP return; // Enough for --raw mode } if (mm->msgtype < 32) printf("CRC: %06x\n", mm->crc); if (mm->correctedbits != 0) printf("No. of bit errors fixed: %d\n", mm->correctedbits); if (mm->signalLevel > 0) printf("RSSI: %.1f dBFS\n", 10 * log10(mm->signalLevel)); if (mm->score) printf("Score: %d\n", mm->score); if (mm->timestampMsg) { if (mm->timestampMsg == MAGIC_MLAT_TIMESTAMP) printf("This is a synthetic MLAT message.\n"); else printf("Time: %.2fus\n", mm->timestampMsg / 12.0); } switch (mm->msgtype) { case 0: printf("DF:0 addr:%06X VS:%u CC:%u SL:%u RI:%u AC:%u\n", mm->addr, mm->VS, mm->CC, mm->SL, mm->RI, mm->AC); break; case 4: printf("DF:4 addr:%06X FS:%u DR:%u UM:%u AC:%u\n", mm->addr, mm->FS, mm->DR, mm->UM, mm->AC); break; case 5: printf("DF:5 addr:%06X FS:%u DR:%u UM:%u ID:%u\n", mm->addr, mm->FS, mm->DR, mm->UM, mm->ID); break; case 11: printf("DF:11 AA:%06X IID:%u CA:%u\n", mm->AA, mm->IID, mm->CA); break; case 16: printf("DF:16 addr:%06x VS:%u SL:%u RI:%u AC:%u MV:", mm->addr, mm->VS, mm->SL, mm->RI, mm->AC); print_hex_bytes(mm->MV, sizeof(mm->MV)); printf("\n"); break; case 17: printf("DF:17 AA:%06X CA:%u ME:", mm->AA, mm->CA); print_hex_bytes(mm->ME, sizeof(mm->ME)); printf("\n"); break; case 18: printf("DF:18 AA:%06X CF:%u ME:", mm->AA, mm->CF); print_hex_bytes(mm->ME, sizeof(mm->ME)); printf("\n"); break; case 20: printf("DF:20 addr:%06X FS:%u DR:%u UM:%u AC:%u MB:", mm->addr, mm->FS, mm->DR, mm->UM, mm->AC); print_hex_bytes(mm->MB, sizeof(mm->MB)); printf("\n"); break; case 21: printf("DF:21 addr:%06x FS:%u DR:%u UM:%u ID:%u MB:", mm->addr, mm->FS, mm->DR, mm->UM, mm->ID); print_hex_bytes(mm->MB, sizeof(mm->MB)); printf("\n"); break; case 24: case 25: case 26: case 27: case 28: case 29: case 30: case 31: printf("DF:24 addr:%06x KE:%u ND:%u MD:", mm->addr, mm->KE, mm->ND); print_hex_bytes(mm->MD, sizeof(mm->MD)); printf("\n"); break; } printf(" %s", df_to_string(mm->msgtype)); if (mm->msgtype == 17 || mm->msgtype == 18) { if (esTypeHasSubtype(mm->metype)) { printf(" %s (%u/%u)", esTypeName(mm->metype, mm->mesub), mm->metype, mm->mesub); } else { printf(" %s (%u)", esTypeName(mm->metype, mm->mesub), mm->metype); } } printf("\n"); if (mm->addr & MODES_NON_ICAO_ADDRESS) { printf(" Other Address: %06X\n", mm->addr); } else { printf(" ICAO Address: %06X\n", mm->addr); } if (mm->airground != AG_INVALID) { printf(" Air/Ground: %s\n", airground_to_string(mm->airground)); } if (mm->altitude_valid) { printf(" Altitude: %d %s %s\n", mm->altitude, altitude_unit_to_string(mm->altitude_unit), altitude_source_to_string(mm->altitude_source)); } if (mm->gnss_delta_valid) { printf(" GNSS delta: %d ft\n", mm->gnss_delta); } if (mm->heading_valid) { printf(" Heading: %u\n", mm->heading); } if (mm->speed_valid) { printf(" Speed: %u kt %s\n", mm->speed, speed_source_to_string(mm->speed_source)); } if (mm->vert_rate_valid) { printf(" Vertical rate: %d ft/min %s\n", mm->vert_rate, altitude_source_to_string(mm->vert_rate_source)); } if (mm->squawk_valid) { printf(" Squawk: %04x\n", mm->squawk); } if (mm->callsign_valid) { printf(" Ident: %s\n", mm->callsign); } if (mm->category_valid) { printf(" Category: %02X\n", mm->category); } if (mm->msgtype == 17 || mm->msgtype == 18) { } if (mm->cpr_valid) { printf(" CPR odd flag: %s\n" " CPR NUCp/NIC: %u\n", mm->cpr_odd ? "odd" : "even", mm->cpr_nucp); if (mm->cpr_decoded) { printf(" CPR latitude: %.5f (%u)\n" " CPR longitude: %.5f (%u)\n" " CPR decoding: %s\n", mm->decoded_lat, mm->cpr_lat, mm->decoded_lon, mm->cpr_lon, mm->cpr_relative ? "local" : "global"); } else { printf(" CPR latitude: (%u)\n" " CPR longitude: (%u)\n" " CPR decoding: none\n", mm->cpr_lat, mm->cpr_lon); } } if (mm->opstatus.valid) { printf(" Aircraft Operational Status:\n"); printf(" Version: %d\n", mm->opstatus.version); printf(" Capability classes: "); if (mm->opstatus.cc_acas) printf("ACAS "); if (mm->opstatus.cc_cdti) printf("CDTI "); if (mm->opstatus.cc_1090_in) printf("1090IN "); if (mm->opstatus.cc_arv) printf("ARV "); if (mm->opstatus.cc_ts) printf("TS "); if (mm->opstatus.cc_tc) printf("TC=%d ", mm->opstatus.cc_tc); if (mm->opstatus.cc_uat_in) printf("UATIN "); if (mm->opstatus.cc_poa) printf("POA "); if (mm->opstatus.cc_b2_low) printf("B2-LOW "); if (mm->opstatus.cc_nac_v) printf("NACv=%d ", mm->opstatus.cc_nac_v); if (mm->opstatus.cc_nic_supp_c) printf("NIC-C=1 "); if (mm->opstatus.cc_lw_valid) printf("L/W=%d ", mm->opstatus.cc_lw); if (mm->opstatus.cc_antenna_offset) printf("GPS-OFFSET=%d ", mm->opstatus.cc_antenna_offset); printf("\n"); printf(" Operational modes: "); if (mm->opstatus.om_acas_ra) printf("ACASRA "); if (mm->opstatus.om_ident) printf("IDENT "); if (mm->opstatus.om_atc) printf("ATC "); if (mm->opstatus.om_saf) printf("SAF "); if (mm->opstatus.om_sda) printf("SDA=%d ", mm->opstatus.om_sda); printf("\n"); if (mm->opstatus.nic_supp_a) printf(" NIC-A: %d\n", mm->opstatus.nic_supp_a); if (mm->opstatus.nac_p) printf(" NACp: %d\n", mm->opstatus.nac_p); if (mm->opstatus.gva) printf(" GVA: %d\n", mm->opstatus.gva); if (mm->opstatus.sil) printf(" SIL: %d (%s)\n", mm->opstatus.sil, (mm->opstatus.sil_type == SIL_PER_HOUR ? "per hour" : "per sample")); if (mm->opstatus.nic_baro) printf(" NICbaro: %d\n", mm->opstatus.nic_baro); if (mm->mesub == 1) printf(" Heading type: %s\n", (mm->opstatus.track_angle == ANGLE_HEADING ? "heading" : "track angle")); printf(" Heading reference: %s\n", (mm->opstatus.hrd == HEADING_TRUE ? "true north" : "magnetic north")); } if (mm->tss.valid) { printf(" Target State and Status:\n"); if (mm->tss.altitude_valid) printf(" Target altitude: %s, %d ft\n", (mm->tss.altitude_type == TSS_ALTITUDE_MCP ? "MCP" : "FMS"), mm->tss.altitude); if (mm->tss.baro_valid) printf(" Altimeter setting: %.1f millibars\n", mm->tss.baro); if (mm->tss.heading_valid) printf(" Target heading: %d\n", mm->tss.heading); if (mm->tss.mode_valid) { printf(" Active modes: "); if (mm->tss.mode_autopilot) printf("autopilot "); if (mm->tss.mode_vnav) printf("VNAV "); if (mm->tss.mode_alt_hold) printf("altitude-hold "); if (mm->tss.mode_approach) printf("approach "); printf("\n"); } printf(" ACAS: %s\n", mm->tss.acas_operational ? "operational" : "NOT operational"); printf(" NACp: %d\n", mm->tss.nac_p); printf(" NICbaro: %d\n", mm->tss.nic_baro); printf(" SIL: %d (%s)\n", mm->tss.sil, (mm->opstatus.sil_type == SIL_PER_HOUR ? "per hour" : "per sample")); } printf("\n"); fflush(stdout); } // //========================================================================= // // When a new message is available, because it was decoded from the RTL device, // file, or received in the TCP input port, or any other way we can receive a // decoded message, we call this function in order to use the message. // // Basically this function passes a raw message to the upper layers for further // processing and visualization // void useModesMessage(struct modesMessage *mm) { struct aircraft *a; ++Modes.stats_current.messages_total; // Track aircraft state a = trackUpdateFromMessage(mm); // In non-interactive non-quiet mode, display messages on standard output if (!Modes.interactive && !Modes.quiet && (!Modes.show_only || mm->addr == Modes.show_only)) { displayModesMessage(mm); } // Feed output clients. // If in --net-verbatim mode, do this for all messages. // Otherwise, apply a sanity-check filter and only // forward messages when we have seen two of them. if (Modes.net) { if (Modes.net_verbatim || mm->msgtype == 32) { // Unconditionally send modesQueueOutput(mm, a); } else if (a->messages > 1) { // If this is the second message, and we // squelched the first message, then re-emit the // first message now. if (!Modes.net_verbatim && a->messages == 2) { modesQueueOutput(&a->first_message, a); } modesQueueOutput(mm, a); } } } // // ===================== Mode S detection and decoding =================== //