Changes to Mode A/C/S matchup code
Try to improve the matching of ModeA/C codes to Known Mode-S
This commit is contained in:
Malcolm Robb
parent
25f92e54ba
commit
2acb0947f0
98
dump1090.c
98
dump1090.c
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@ -75,6 +75,10 @@
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#define MODEAC_MSG_SQUELCH_LEVEL 0x07FF /* Average signal strength limit */
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#define MODEAC_MSG_FLAG (1<<0)
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#define MODEAC_MSG_MODES_HIT (1<<1)
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#define MODEAC_MSG_MODEA_HIT (1<<2)
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#define MODEAC_MSG_MODEC_HIT (1<<3)
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#define MODEAC_MSG_MODEA_ONLY (1<<4)
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#define MODEAC_MSG_MODEC_OLD (1<<5)
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#define MODES_PREAMBLE_US 8 /* microseconds = bits */
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#define MODES_PREAMBLE_SAMPLES (MODES_PREAMBLE_US * 2)
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@ -286,9 +290,6 @@ struct modesMessage {
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int um; /* Request extraction of downlink request. */
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int modeA; /* 13 bits identity (Squawk). */
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// DF32 ModeA & Mode C
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int modeC; /* Decoded Mode C */
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/* Fields used by multiple message types. */
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int altitude, unit;
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};
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@ -1005,7 +1006,7 @@ int detectModeA(uint16_t *m, struct modesMessage *mm)
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}
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// Input format is : 00:A4:A2:A1:00:B4:B2:B1:00:C4:C2:C1:00:D4:D2:D1
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int ModeAToModeC(unsigned int ModeA )
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int ModeAToModeC(unsigned int ModeA)
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{
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unsigned int FiveHundreds = 0;
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unsigned int OneHundreds = 0;
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@ -1062,10 +1063,6 @@ void decodeModeAMessage(struct modesMessage *mm, int ModeA)
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// Flag ident in flight status
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mm->fs = ModeA & 0x0080;
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// Convert ModeA to ModeC and use as an altitude
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mm->modeC = ModeAToModeC(ModeA);
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mm->altitude = mm->modeC * 100;
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// Not much else we can tell from a Mode A/C reply.
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// Just fudge up a few bits to keep other code happy
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mm->crcok = 1;
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@ -1543,7 +1540,6 @@ void decodeModesMessage(struct modesMessage *mm, unsigned char *msg) {
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if (mm->msgtype == 0 || mm->msgtype == 4 ||
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mm->msgtype == 16 || mm->msgtype == 20) {
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mm->altitude = decodeAC13Field(msg, &mm->unit);
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mm->modeC = (mm->altitude + 49) / 100;
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}
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/* Decode extended squitter specific stuff. */
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@ -1567,7 +1563,6 @@ void decodeModesMessage(struct modesMessage *mm, unsigned char *msg) {
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mm->fflag = msg[6] & (1<<2);
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mm->tflag = msg[6] & (1<<3);
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mm->altitude = decodeAC12Field(msg,&mm->unit);
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mm->modeC = (mm->altitude + 49) / 100;
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mm->raw_latitude = ((msg[6] & 3) << 15) |
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(msg[7] << 7) |
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(msg[8] >> 1);
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@ -1742,9 +1737,10 @@ void displayModesMessage(struct modesMessage *mm) {
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if (mm->fs & 0x0080) {
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printf(" Mode A : %04x IDENT\n", mm->modeA);
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} else {
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int modeC = ModeAToModeC(mm->modeA);
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printf(" Mode A : %04x\n", mm->modeA);
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if (mm->altitude >= -1300)
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{printf(" Mode C : %d feet\n", mm->altitude);}
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if (modeC >= -13)
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{printf(" Mode C : %d feet\n", (modeC * 100));}
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}
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} else {
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@ -2170,10 +2166,19 @@ struct aircraft *interactiveCreateAircraft(struct modesMessage *mm) {
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a->sbsflags = 0;
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a->seen = time(NULL);
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a->messages = 0;
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if (mm->msgtype == 32) {
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a->modeACflags = MODEAC_MSG_FLAG;
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a->modeA = mm->modeA;
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a->modeC = ModeAToModeC(mm->modeA | mm->fs);
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a->altitude = a->modeC * 100;
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if (a->modeC < -12)
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{a->modeACflags |= MODEAC_MSG_MODEA_ONLY;}
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} else {
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a->modeACflags = 0;
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a->modeA = 0;
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a->modeC = 0;
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a->altitude = 0;
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}
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a->modeAcount = 0;
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a->modeCcount = 0;
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a->next = NULL;
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@ -2223,17 +2228,23 @@ void interactiveUpdateAircraftModeA(struct aircraft *a) {
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// First check for Mode-A <=> Mode-S Squawk matches
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if (a->modeA == b->modeA) { // If a 'real' Mode-S ICAO exists using this Mode-A Squawk
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b->modeAcount++;
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b->modeAcount = a->messages;
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a->modeACflags |= MODEAC_MSG_MODEA_HIT;
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if ( (b->modeAcount > 0) &&
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((b->modeCcount > 1) || (a->modeC < -12)) )
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( (b->modeCcount > 1)
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|| (a->modeACflags & MODEAC_MSG_MODEA_ONLY)) ) // Allow Mode-A only matches if this Mode-A is invalid Mode-C
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{a->modeACflags |= MODEAC_MSG_MODES_HIT;} // flag this ModeA/C probably belongs to a known Mode S
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}
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// Next check for Mode-C <=> Mode-S Altitude matches
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if (a->modeC == b->modeC) { // If a 'real' Mode S ICAO exists at this Mode-C Altitude
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b->modeCcount++;
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if ((b->modeAcount > 0) && (b->modeCcount > 1))
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{a->modeACflags |= MODEAC_MSG_MODES_HIT;} // flag this ModeA/C probably belongs to a known Mode S
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if ( (a->modeC == b->modeC ) // If a 'real' Mode-S ICAO exists at this Mode-C Altitude
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|| (a->modeC == b->modeC + 1) // or this Mode-C - 100 ft
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|| (a->modeC + 1 == b->modeC ) ) { // or this Mode-C + 100 ft
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b->modeCcount = a->messages;
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a->modeACflags |= MODEAC_MSG_MODEC_HIT;
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if ( (b->modeAcount > 0) &&
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(b->modeCcount > 1) )
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{a->modeACflags |= (MODEAC_MSG_MODES_HIT | MODEAC_MSG_MODEC_OLD);} // flag this ModeA/C probably belongs to a known Mode S
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}
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}
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b = b->next;
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@ -2247,8 +2258,8 @@ void interactiveUpdateAircraftModeS() {
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int flags = a->modeACflags;
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if (flags & MODEAC_MSG_FLAG) { // find any fudged ICAO records
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// clear the hit bit
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a->modeACflags = flags & ~MODEAC_MSG_MODES_HIT;
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// clear the current A,C and S hit bits ready for this attempt
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a->modeACflags = flags & ~(MODEAC_MSG_MODEA_HIT | MODEAC_MSG_MODEC_HIT | MODEAC_MSG_MODES_HIT);
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interactiveUpdateAircraftModeA(a); // and attempt to match them with Mode-S
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}
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@ -2488,28 +2499,29 @@ struct aircraft *interactiveReceiveData(struct modesMessage *mm) {
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if (mm->msgtype == 0 || mm->msgtype == 4 || mm->msgtype == 20) {
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if ( (a->modeCcount) // if we've a modeCcount already
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&& (a->modeC != mm->modeC ) // and Altitude has changed
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&& (a->modeC != mm->modeC + 1) // and Altitude not changed by +100 feet
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&& (a->modeC + 1 != mm->modeC ) ) // and Altitude not changes by -100 feet
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&& (a->altitude != mm->altitude ) ) // and Altitude has changed
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// && (a->modeC != mm->modeC + 1) // and Altitude not changed by +100 feet
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// && (a->modeC + 1 != mm->modeC ) ) // and Altitude not changes by -100 feet
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{a->modeCcount = 0;} //....zero the hit count
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a->altitude = mm->altitude;
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a->modeC = mm->modeC;
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a->modeC = (mm->altitude + 49) / 100;
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} else if(mm->msgtype == 5 || mm->msgtype == 21) {
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if (a->modeA != mm->modeA) {
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a->modeAcount = 0; // Squawk has changed, so zero the hit count
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}
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a->modeA = mm->modeA;
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} else if (mm->msgtype == 17) {
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if (mm->metype >= 1 && mm->metype <= 4) {
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memcpy(a->flight, mm->flight, sizeof(a->flight));
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} else if (mm->metype >= 9 && mm->metype <= 18) {
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if ( (a->modeCcount) // if we've a modeCcount already
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&& (a->modeC != mm->modeC ) // and Altitude has changed
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&& (a->modeC != mm->modeC + 1) // and Altitude not changed by +100 feet
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&& (a->modeC + 1 != mm->modeC ) ) // and Altitude not changes by -100 feet
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&& (a->altitude != mm->altitude ) ) // and Altitude has changed
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// && (a->modeC != mm->modeC + 1) // and Altitude not changed by +100 feet
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// && (a->modeC + 1 != mm->modeC ) ) // and Altitude not changes by -100 feet
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{a->modeCcount = 0;} //....zero the hit count
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a->altitude = mm->altitude;
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a->modeC = mm->modeC;
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a->modeC = (mm->altitude + 49) / 100;
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if (mm->fflag) {
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a->odd_cprlat = mm->raw_latitude;
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a->odd_cprlon = mm->raw_longitude;
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@ -2534,11 +2546,24 @@ struct aircraft *interactiveReceiveData(struct modesMessage *mm) {
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}
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}
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} else if(mm->msgtype == 32) {
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a->modeACflags = MODEAC_MSG_FLAG;
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a->modeA = mm->modeA;
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a->modeC = mm->modeC;
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a->altitude = mm->altitude;
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interactiveUpdateAircraftModeA(a);
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int flags = a->modeACflags;
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if ((flags & (MODEAC_MSG_MODEC_HIT | MODEAC_MSG_MODEC_OLD)) == MODEAC_MSG_MODEC_OLD) {
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//
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// This Mode-C doesn't currently hit any known Mode-S, but it used to because MODEAC_MSG_MODEC_OLD is
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// set So the aircraft it used to match has either changed altitude, or gone out of our receiver range
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//
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// We've now received this Mode-A/C again, so it must be a new aircraft. It could be another aircraft
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// at the same Mode-C altitude, or it could be a new airctraft with a new Mods-A squawk.
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//
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// To avoid masking this aircraft from the interactive display, clear the MODEAC_MSG_MODES_OLD flag
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// and set messages to 1;
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//
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a->modeACflags = flags & ~MODEAC_MSG_MODEC_OLD;
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a->messages = 1;
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}
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}
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return a;
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}
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@ -2573,9 +2598,10 @@ void interactiveShowData(void) {
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char gs[5] = " ";
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char spacer = '\0';
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if ( ((a->modeACflags & MODEAC_MSG_FLAG) == 0)
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|| (((a->modeACflags & MODEAC_MSG_MODES_HIT) == 0) && (altitude == 0) && (msgs > 4))
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|| (((a->modeACflags & MODEAC_MSG_MODES_HIT) == 0) && (msgs > 127)) ) {
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if ( (((a->modeACflags & (MODEAC_MSG_FLAG )) == 0 ) )
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|| (((a->modeACflags & (MODEAC_MSG_MODES_HIT | MODEAC_MSG_MODEA_ONLY)) == MODEAC_MSG_MODEA_ONLY) && (msgs > 4 ) )
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|| (((a->modeACflags & (MODEAC_MSG_MODES_HIT | MODEAC_MSG_MODEC_OLD )) == 0 ) && (msgs > 127) )
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) {
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/* Convert units to metric if --metric was specified. */
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if (Modes.metric) {
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