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Generate an average Signal Strength

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Remember the last 8 signal strengths for each aircraft and average them
for --interactive display. This produces a less jittery indication.
This commit is contained in:
Malcolm Robb 2013-04-30 18:03:30 +01:00
parent a296f2783f
commit 9783b4786a
1 changed files with 26 additions and 21 deletions
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47
dump1090.c
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@ -137,31 +137,30 @@ struct client {
int buflen; /* Amount of data on buffer. */ int buflen; /* Amount of data on buffer. */
}; };
/* Structure used to describe an aircraft in iteractive mode. */ // Structure used to describe an aircraft in iteractive mode
struct aircraft { struct aircraft {
uint32_t addr; /* ICAO address */ uint32_t addr; // ICAO address
char flight[9]; /* Flight number */ char flight[9]; // Flight number
unsigned char signalLevel; /* Signal Amplitude */ unsigned char signalLevel[8]; // Last 8 Signal Amplitudes
int altitude; /* Altitude */ int altitude; // Altitude
int speed; /* Velocity computed from EW and NS components. */ int speed; // Velocity computed from EW and NS components
int track; /* Angle of flight. */ int track; // Angle of flight
time_t seen; /* Time at which the last packet was received. */ time_t seen; // Time at which the last packet was received
long messages; /* Number of Mode S messages received. */ long messages; // Number of Mode S messages received
int modeA; /* Squawk */ int modeA; // Squawk
int modeC; /* Altitude */ int modeC; // Altitude
long modeAcount; /* Mode A Squawk hit Count */ long modeAcount; // Mode A Squawk hit Count
long modeCcount; /* Mode C Altitude hit Count */ long modeCcount; // Mode C Altitude hit Count
int modeACflags; /* Flags for mode A/C recognition */ int modeACflags; // Flags for mode A/C recognition
/* Encoded latitude and longitude as extracted by odd and even // Encoded latitude and longitude as extracted by odd and even CPR encoded messages
* CPR encoded messages. */
int odd_cprlat; int odd_cprlat;
int odd_cprlon; int odd_cprlon;
int even_cprlat; int even_cprlat;
int even_cprlon; int even_cprlon;
double lat, lon; /* Coordinated obtained from CPR encoded data. */ double lat, lon; // Coordinated obtained from CPR encoded data
int sbsflags; int sbsflags;
uint64_t odd_cprtime, even_cprtime; uint64_t odd_cprtime, even_cprtime;
struct aircraft *next; /* Next aircraft in our linked list. */ struct aircraft *next; // Next aircraft in our linked list
}; };
/* Program global state. */ /* Program global state. */
@ -2139,6 +2138,8 @@ struct aircraft *interactiveCreateAircraft(struct modesMessage *mm) {
a->addr = mm->addr; a->addr = mm->addr;
a->flight[0] = '\0'; a->flight[0] = '\0';
memset(a->signalLevel, mm->signalLevel, 8); // First time, initialise everything
// to the first signal strength
a->speed = 0; a->speed = 0;
a->track = 0; a->track = 0;
a->odd_cprlat = 0; a->odd_cprlat = 0;
@ -2482,9 +2483,9 @@ struct aircraft *interactiveReceiveData(struct modesMessage *mm) {
} }
} }
a->signalLevel[a->messages & 7] = mm->signalLevel;// replace the 8th oldest signal strength
a->seen = time(NULL); a->seen = time(NULL);
a->messages++; a->messages++;
a->signalLevel = mm->signalLevel;
if (mm->msgtype == 0 || mm->msgtype == 4 || mm->msgtype == 20) { if (mm->msgtype == 0 || mm->msgtype == 4 || mm->msgtype == 20) {
if ( (a->modeCcount) // if we've a modeCcount already if ( (a->modeCcount) // if we've a modeCcount already
@ -2637,7 +2638,11 @@ void interactiveShowData(void) {
a->addr, a->flight, fl, gs, tt, squawk, msgs, (int)(now - a->seen)); a->addr, a->flight, fl, gs, tt, squawk, msgs, (int)(now - a->seen));
} else { } else {
char mode[5] = " \0"; char mode[5] = " \0";
unsigned char * pSig = a->signalLevel;
unsigned int signalAverage = (pSig[0] + pSig[1] + pSig[2] + pSig[3] +
pSig[4] + pSig[5] + pSig[6] + pSig[7] + 3) >> 3;
if ((flags & MODEAC_MSG_FLAG) == 0) { if ((flags & MODEAC_MSG_FLAG) == 0) {
mode[0] = 'S'; mode[0] = 'S';
} else if (flags & MODEAC_MSG_MODEA_ONLY) { } else if (flags & MODEAC_MSG_MODEA_ONLY) {
@ -2648,7 +2653,7 @@ void interactiveShowData(void) {
printf("%06x %-4s %-4s %-8s %5d %3d %3d %7.03f %8.03f %3d %5d %2d\n", printf("%06x %-4s %-4s %-8s %5d %3d %3d %7.03f %8.03f %3d %5d %2d\n",
a->addr, mode, squawk, a->flight, altitude, speed, a->track, a->addr, mode, squawk, a->flight, altitude, speed, a->track,
a->lat, a->lon, a->signalLevel, msgs, (int)(now - a->seen)); a->lat, a->lon, signalAverage, msgs, (int)(now - a->seen));
} }
count++; count++;
} }