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adding altitude and UDP out
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@diehardsk
diehardsk authored Jan 25, 2023
1 parent 7a0eeb9 commit 5adba88
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8 changes: 5 additions & 3 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -9,15 +9,17 @@ Following data is relevant for both types:
- Windfinding is provided by Radiotheodolite system

## DECODING
These decoders are based on [rs92mod.c](https://github.com/rs1729/RS/blob/master/demod/mod/rs92mod.c) and [rs41mod.c](https://github.com/rs1729/RS/blob/master/demod/mod/rs41mod.c) code by zilog80. They require FM demodulated WAV audio by default. This might be a wave file record or stream provided by [SOX](https://sourceforge.net/projects/sox/) from pipe or from PC audio comming out of SDR application. Output is text and/or json data.
These decoders are based on [rs92mod.c](https://github.com/rs1729/RS/blob/master/demod/mod/rs92mod.c) and [rs41mod.c](https://github.com/rs1729/RS/blob/master/demod/mod/rs41mod.c) code by zilog80. They require FM demodulated WAV audio by default. This might be a wave file record or stream provided by [SOX](https://sourceforge.net/projects/sox/) from pipe or from PC audio comming out of SDR application. Output is text and/or json data. It allows sending json over UDP at the same time.

Example of using SoX in windows to stream from virtual audio device:
```
SOX_PATH\sox -q -t waveaudio "CABLE Output" -t wav - 2>nul | RS92D.exe
```
Wave audio file decoding with signal inversion and JSON output:
Wave audio file decoding and reporting number of corrected frame bytes (Linux):
```
RS41D --invert --jsnonly record.wav
./RS41D --eccn record.wav
```
![output](images/test_and_options.png)

## RADIOSONDE HUNTING
Tracking and physically finding radiosonde that does not transmit its position is challenging. Received air pressure data gives us approximate altitude and also allows us to calculate vertical speed. If we know launch location, it is possible to estimate impact location using wind forecast data. RS92-D battery operation time is ~4.5 hours. But the major problem would be that we basically need a direct line of sight to receive signal.
Expand Down
214 changes: 185 additions & 29 deletions RS41D.c
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,10 @@
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <sys/socket.h>
#include <netdb.h>
#include <unistd.h>
#include <time.h>

#ifdef CYGWIN
#include <fcntl.h> // cygwin: _setmode()
Expand Down Expand Up @@ -64,15 +68,26 @@ typedef struct {
i8_t jsn; // JSON output
i8_t slt; // silent (only raw/json)
i8_t dbg;
i8_t udp;
i8_t arx;
} option_t;

typedef struct {
char *host;
char *port;
int sfd;
time_t ip_time;
} hostcfg_t;
static hostcfg_t hostcfg;

typedef struct {
int msglen;
int msgpos;
int parpos;
} rscfg_t;

static rscfg_t cfg_rs41 = { 240-6-24, 6+24, 6 };
static char *key[10], *val[10];
static char ecnt;

#define BITS (1+8+1) // 10

Expand Down Expand Up @@ -136,9 +151,9 @@ typedef struct {
int out;
int frnr;
char id[9];
double alt;
float T; float RH; float TH;
float P;
i32_t alt;
ui32_t crc;
ui8_t frame[FRAME_LEN];
ui8_t calibytes[51*16];
Expand All @@ -160,9 +175,9 @@ typedef struct {
int jsn_freq; // freq/kHz (SDR)
float batt; // battery voltage (V)
ui16_t conf_fw; // firmware
ui16_t conf_kt; // kill timer (sec)
ui16_t conf_bt; // burst timer (sec)
ui16_t conf_cd; // kill countdown (sec) (kt or bt)
i16_t conf_kt; // kill timer (sec)
i16_t conf_bt; // burst timer (sec)
i16_t conf_cd; // kill countdown (sec) (kt or bt)
ui8_t conf_bk; // burst kill
ui8_t burst; // burst detected (by sonde)
char rstyp[9]; // RS41-SG, RS41-SGP
Expand Down Expand Up @@ -225,6 +240,57 @@ static int i2(ui8_t *bytes) { // 16bit signed int
return val;
}

static int send_UDP(char *message) {
struct addrinfo hints;
struct addrinfo *result, *rp;
int s;
size_t len;
double elap_minutes;
time_t time_now = time(NULL);

elap_minutes = difftime(time_now, hostcfg.ip_time)/60;
if (hostcfg.sfd == -1 || elap_minutes > 60) { //max once per hour
fprintf(stderr, "resolving IP.. ");
if (hostcfg.sfd != -1)
close(hostcfg.sfd);
memset(&hints, 0, sizeof(struct addrinfo));
hints.ai_family = AF_UNSPEC; /* Allow IPv4 or IPv6 */
hints.ai_socktype = SOCK_DGRAM; /* Datagram socket */
hints.ai_flags = 0;
hints.ai_protocol = 0; /* Any protocol */

s = getaddrinfo(hostcfg.host, hostcfg.port, &hints, &result);
if (s != 0) {
fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(s));
freeaddrinfo(result);
return -1;
}
for (rp = result; rp != NULL; rp = rp->ai_next) {
hostcfg.sfd = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
if (hostcfg.sfd == -1)
continue;
if (connect(hostcfg.sfd, rp->ai_addr, rp->ai_addrlen) != -1)
break; /* Success */
close(hostcfg.sfd);
hostcfg.sfd = -1;
}
if (rp == NULL) { /* No address succeeded */
fprintf(stderr, "could not connect to host\n");
freeaddrinfo(result);
return -2;
}
freeaddrinfo(result);
hostcfg.ip_time = time(NULL);
fprintf(stderr, "success\n");
}

len = strlen(message);
if (write(hostcfg.sfd, message, len) != len) {
fprintf(stderr, "Unable to send UDP message\n");
return -3;
}
}

static int crc16(gpx_t *gpx, int start, int len) {
int crc16poly = 0x1021;
int rem = 0xFFFF, i, j;
Expand Down Expand Up @@ -321,7 +387,7 @@ static int get_SondeID(gpx_t *gpx, int crc, int ofs) {
memset(gpx->rstyp, 0, 9);
gpx->freq = 0;
gpx->conf_fw = 0;
gpx->conf_bt = 0;
gpx->conf_bt = -1;
gpx->conf_bk = 0;
gpx->conf_cd = -1;
gpx->conf_kt = -1;
Expand All @@ -330,6 +396,7 @@ static int get_SondeID(gpx_t *gpx, int crc, int ofs) {
gpx->T = -273.15f;
gpx->RH = -1.0f;
gpx->P = -1.0f;
gpx->alt = -10000;
// new ID:
memcpy(gpx->id, sondeid_bytes, 8);
gpx->id[8] = '\0';
Expand Down Expand Up @@ -499,6 +566,41 @@ static float get_P(gpx_t *gpx, ui32_t f, ui32_t f1, ui32_t f2, int fx)
}
// ---------------------------------------------------------------------------------------
//
// Altitude calculation using barometric formula for standard atmosphere
static int calc_PAlt(gpx_t *gpx) {
float Pb, Tb, Lb, hb, RgM = 8.31446/(9.80665*0.0289644);
float pressure = gpx->P; //hPa

if (pressure <= 0.0f) return -1;
if (pressure < 8.6802) {
Pb = 8.6802;
Tb = 228.65;
Lb = 0.0028;
hb = 32000.0;
}
else if (pressure < 54.7489) {
Pb = 54.7489;
Tb = 216.65;
Lb = 0.001;
hb = 20000.0;
}
else if (pressure < 226.321) {
Pb = 226.321;
Tb = 216.65;
Lb = 0.0;
hb = 11000.0;
}
else {
Pb = 1013.25;
Tb = 288.15;
Lb = -0.0065;
hb = 0.0;
}

if (Lb == 0.0) gpx->alt = round(hb - RgM*Tb*log(pressure/Pb));
else gpx->alt = round(hb + Tb/Lb*(pow(pressure/Pb, -RgM*Lb)-1.0));
return 0;
}


static int get_PTU(gpx_t *gpx, int ofs, int pck) {
Expand Down Expand Up @@ -559,6 +661,7 @@ static int get_PTU(gpx_t *gpx, int ofs, int pck) {
}
gpx->P = P;

calc_PAlt(gpx);

if (gpx->option.dbg == 1 && (gpx->crc & crc_PTU)==0)
{
Expand All @@ -577,7 +680,7 @@ static int get_PTU(gpx_t *gpx, int ofs, int pck) {
printf(" TH:%.2f ", TH);
}
printf("\n");
printf(" %9.2f ; %6.1f ; %6.1f ", gpx->alt, gpx->ptu_Rf1, gpx->ptu_Rf2);
printf(" %6.1f ; %6.1f ", gpx->ptu_Rf1, gpx->ptu_Rf2);
printf("; %10.6f ; %10.6f ; %10.6f ", gpx->ptu_calT1[0], gpx->ptu_calT1[1], gpx->ptu_calT1[2]);
//printf("; %8d ; %8d ; %8d ", meas[0], meas[1], meas[2]);
printf("; %10.6f ; %10.6f ", gpx->ptu_calH[0], gpx->ptu_calH[1]);
Expand Down Expand Up @@ -727,6 +830,7 @@ static int prn_ptu(gpx_t *gpx) {
if (gpx->P > 0.0) {
if (gpx->P < 100.0) fprintf(stdout, " P=%.2fhPa ", gpx->P);
else fprintf(stdout, " P=%.1fhPa ", gpx->P);
if (gpx->alt > -10000) fprintf(stdout, " alt=%dm ", gpx->alt);
}

// dew point
Expand All @@ -749,7 +853,7 @@ static int print_position(gpx_t *gpx, int ec) {
int err = 0, err0 = 0;
int out;
int ofs_ptu = 0, pck_ptu = 0;
if (gpx->option.slt) out = 0; else out = 1;
if (gpx->option.slt || gpx->option.jsn==2) out = 0; else out = 1;

if ( ec >= 0 )
{
Expand Down Expand Up @@ -819,43 +923,81 @@ static int print_position(gpx_t *gpx, int ec) {

if (out) fprintf(stdout, "\n");

if (gpx->option.jsn) {
if (gpx->option.jsn || gpx->option.udp) {
// Print out telemetry data as JSON
if (!err && !err0) {
char str[200], sentence[1000];
char *ver_jsn = NULL;
fprintf(stdout, "{ \"type\": \"%s\"", "RS41");
fprintf(stdout, ", \"frame\": %d, \"id\": \"%s\", \"bt\": %d, \"cd\": %d, \"batt\": %.2f, \"burst\": %d",
gpx->frnr, gpx->id, gpx->conf_bt, gpx->conf_cd, gpx->batt, gpx->burst);
sprintf(sentence, "{\"type\":\"RS41\", \"subtype\":\"RS41-D\"");
sprintf(str, ", \"frame\":%d, \"id\":\"%s\", \"batt\":%.2f, \"burst\":%d",
gpx->frnr, gpx->id, gpx->batt, gpx->burst);
strcat(sentence, str);
if (gpx->conf_bt >= 0) {
sprintf(str, ", \"bt\":%d", gpx->conf_bt );
strcat(sentence, str);
}
if (gpx->conf_cd >= 0) {
sprintf(str, ", \"cd\":%d", gpx->conf_cd );
strcat(sentence, str);
}
if (gpx->option.ptu) {
float _RH = gpx->RH;
if (gpx->T > -273.0) {
fprintf(stdout, ", \"temp\": %.1f", gpx->T );
sprintf(str, ", \"temp\":%.1f", gpx->T );
strcat(sentence, str);
}
if (_RH > -0.5) {
fprintf(stdout, ", \"humidity\": %.1f", _RH );
sprintf(str, ", \"humidity\":%.1f", _RH );
strcat(sentence, str);
}
if (gpx->P > 0.0) {
fprintf(stdout, ", \"pressure\": %.2f", gpx->P );
sprintf(str, ", \"pressure\":%.2f", gpx->P );
strcat(sentence, str);
}
if (gpx->alt >-10000 || gpx->option.arx) {
sprintf(str, ", \"alt\":%d", gpx->alt);
strcat(sentence, str);
}
}
fprintf(stdout, ", \"subtype\": \"%s\"", "RS41-D" );
if (gpx->jsn_freq > 0) { // rs41-frequency: gpx->freq
int fq_kHz = gpx->jsn_freq;
if (gpx->freq > 0) fq_kHz = gpx->freq;
fprintf(stdout, ", \"freq\": %d", fq_kHz);
sprintf(str, ", \"freq\":%d", fq_kHz);
strcat(sentence, str);
}

// Include frequency derived from subframe information if available.
if (gpx->freq > 0) {
fprintf(stdout, ", \"tx_frequency\": %d", gpx->freq );
sprintf(str, ", \"tx_frequency\":%d", gpx->freq );
strcat(sentence, str);
}
if (gpx->option.arx) {
time_t now;
now = time(NULL);
char dt_now[sizeof "2023-01-01T07:35:00Z"];
strftime(dt_now, sizeof dt_now, "%FT%TZ", gmtime(&now));
sprintf(str, ", \"datetime\":\"%s\", \"lat\":0.0, \"lon\":0.0", dt_now );
strcat(sentence, str);
}

#ifdef VER_JSN_STR
ver_jsn = VER_JSN_STR;
#endif
if (ver_jsn && *ver_jsn != '\0') fprintf(stdout, ", \"version\": \"%s\"", ver_jsn);
fprintf(stdout, " }\n");
if (gpx->option.jsn<2) fprintf(stdout, "\n");
if (ver_jsn && *ver_jsn != '\0') {
sprintf(str, ", \"version\":\"%s\"", ver_jsn);
strcat(sentence, str);
}
for (int i = 0; i < ecnt; i++) {
sprintf(str, ", \"%s\":\"%s\"", key[i], val[i]);
strcat(sentence, str);
}
strcat(sentence, "}");
if (!gpx->option.slt && gpx->option.jsn) {
fprintf(stdout, "%s", sentence); //JSON string to sdout
fprintf(stdout, "\n");
}
if (!gpx->option.slt && gpx->option.jsn==1) fprintf(stdout, "\n");
if (gpx->option.udp) //UDP packet
send_UDP(sentence);
}
}
}
Expand Down Expand Up @@ -1012,7 +1154,6 @@ int main(int argc, char *argv[]) {
#endif
setbuf(stdout, NULL);


fpname = argv[0];
++argv;
while ((*argv) && (!fileloaded)) {
Expand All @@ -1027,12 +1168,14 @@ int main(int argc, char *argv[]) {
fprintf(stderr, " --ths <x> (peak threshold; default=%.1f)\n", thres);
fprintf(stderr, " --json (adds JSON output)\n");
fprintf(stderr, " --jsnonly (exclusively JSON out)\n");
fprintf(stderr, " -u <host> <port> (UDP JSON output)\n");
return 0;
}
else if ( (strcmp(*argv, "-v") == 0) ) { }
else if ( (strcmp(*argv, "--sub") == 0) ) { gpx.option.sub = 1; }
else if ( (strcmp(*argv, "--aux") == 0) ) { }
else if (strcmp(*argv, "--jsnonly") == 0) { gpx.option.jsn = 2; gpx.option.slt = 1;}
else if (strcmp(*argv, "--json") == 0) { gpx.option.jsn = 1;}
else if (strcmp(*argv, "--jsnonly") == 0) { gpx.option.jsn = 2;}
else if (strcmp(*argv, "--eccn") == 0) { gpx.option.ecn = 1; }
else if (strcmp(*argv, "--ptu" ) == 0) { gpx.option.ptu = 1; }
else if (strcmp(*argv, "--dewp") == 0) { gpx.option.dwp = 1; }
Expand All @@ -1042,9 +1185,6 @@ int main(int argc, char *argv[]) {
else if ( (strcmp(*argv, "-i") == 0) || (strcmp(*argv, "--invert") == 0) ) {
gpx.option.inv = 1;
}
else if (strcmp(*argv, "--json") == 0) {
gpx.option.jsn = 1;
}
else if (strcmp(*argv, "--jsn_cfq") == 0) {
int frq = -1; // center frequency / Hz
++argv;
Expand Down Expand Up @@ -1102,9 +1242,9 @@ int main(int argc, char *argv[]) {
option_min = 1;
}
*/
else if (strcmp(*argv, "--dbg" ) == 0) { gpx.option.dbg = 1; }
else if (strcmp(*argv, "--dbg" ) == 0) { gpx.option.dbg = 1; }
else if (strcmp(*argv, "--rawhex") == 0) { rawhex = 2; } // raw hex input
else if (strcmp(*argv, "-") == 0) {
/* else if (strcmp(*argv, "-") == 0) {
int sample_rate = 0, bits_sample = 0, channels = 0;
++argv;
if (*argv) sample_rate = atoi(*argv); else return -1;
Expand All @@ -1120,6 +1260,22 @@ int main(int argc, char *argv[]) {
pcm.nch = channels;
option_pcmraw = 1;
}
*/ else if (strcmp(*argv, "-u") == 0) {
gpx.option.udp = 1;
hostcfg.sfd = -1;
++argv;
if (*argv) hostcfg.host = *argv; else return -1;
++argv;
if (*argv) hostcfg.port = *argv; else return -1;
}
else if (strcmp(*argv, "--autorx") == 0) { gpx.option.arx = 1;}
else if (strcmp(*argv, "--add") == 0) {
++argv;
if (*argv) key[ecnt] = *argv; else return -1;
++argv;
if (*argv) val[ecnt] = *argv; else return -1;
++ecnt;
}
else {
fp = fopen(*argv, "rb");
if (fp == NULL) {
Expand Down
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