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skytraq.c
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skytraq.c
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/*------------------------------------------------------------------------------
* skytraq.c : skytraq receiver dependent functions
*
* Copyright (C) 2009-2011 by T.TAKASU, All rights reserved.
*
* reference :
* [1] Skytraq, Application Note AN0023 Binary Message of SkyTraq Venus 6
* GPS Receiver, ver 1.4.8, August 21, 2008
* [2] Skytraq, Application Note AN0024 Raw Measurement Binary Message
* Extension of SkyTraq Venus 6 GPS Receiver, ver 0.5, October 9, 2009
*
* notes :
* The byte order of S1315F raw message is big-endian inconsistent to [1].
*
* version : $Revision:$
* history : 2009/10/10 1.0 new
* 2009/11/08 1.1 flip carrier-phase polarity for F/W 1.8.23-20091106
* 2011/05/27 1.2 add almanac decoding
* fix problem with ARM compiler
*-----------------------------------------------------------------------------*/
#include "rtklib.h"
#define STQSYNC1 0xA0 /* skytraq binary sync code 1 */
#define STQSYNC2 0xA1 /* skytraq binary sync code 2 */
#define ID_STQTIME 0xDC /* skytraq message id: measurement time info */
#define ID_STQRAW 0xDD /* skytraq message id: raw channel measurement */
#define ID_STQSFRB 0xE0 /* skytraq message id: subframe buffer data */
#define ID_RESTART 0x01 /* skytraq message id: system restart */
#define ID_CFGSERI 0x05 /* skytraq message id: configure serial port */
#define ID_CFGFMT 0x09 /* skytraq message id: configure message format */
#define ID_CFGRATE 0x12 /* skytraq message id: configure message rate */
static const char rcsid[]="$Id:$";
/* extract field (big-endian) ------------------------------------------------*/
#define U1(p) (*((unsigned char *)(p)))
#define I1(p) (*((char *)(p)))
static unsigned short U2(unsigned char *p)
{
unsigned char b[2];
b[0]=p[1]; b[1]=p[0];
return *(unsigned short *)b;
}
static unsigned int U4(unsigned char *p)
{
unsigned char b[4];
b[0]=p[3]; b[1]=p[2]; b[2]=p[1]; b[3]=p[0];
return *(unsigned int *)b;
}
static float R4(unsigned char *p)
{
unsigned char b[4];
b[0]=p[3]; b[1]=p[2]; b[2]=p[1]; b[3]=p[0];
return *(float *)b;
}
static double R8(unsigned char *p)
{
double value;
unsigned char *q=(unsigned char *)&value+7;
int i;
for (i=0;i<8;i++) *q--=*p++;
return value;
}
/* checksum ------------------------------------------------------------------*/
static unsigned char checksum(unsigned char *buff, int len)
{
unsigned char cs=0;
int i;
for (i=4;i<len-3;i++) {
cs^=buff[i];
}
return cs;
}
/* decode skytraq measurement time info --------------------------------------*/
static int decode_stqtime(raw_t *raw)
{
unsigned char *p=raw->buff+4;
double tow;
int week;
trace(4,"decode_stqtime: len=%d\n",raw->len);
raw->iod=U1(p+1);
week =U2(p+2);
tow =U4(p+4)*0.001;
raw->time=gpst2time(week,tow);
return 0;
}
/* decode skytraq raw channel mesurement -------------------------------------*/
static int decode_stqraw(raw_t *raw)
{
int i,j,iod,prn,sat,n=0,nsat;
unsigned char *p=raw->buff+4,ind;
trace(4,"decode_stqraw: len=%d\n",raw->len);
iod=U1(p+1);
if (iod!=raw->iod) {
trace(2,"stq raw iod error: iod=%d %d\n",iod,raw->iod);
return -1;
}
nsat=U1(p+2);
if (raw->len<8+23*nsat) {
trace(2,"stq raw length error: len=%d nsat=%d\n",raw->len,nsat);
return -1;
}
for (i=0,p+=3;i<nsat&&i<MAXOBS;i++,p+=23) {
ind =U1(p+22);
prn =U1(p);
raw->obs.data[n].SNR[0]=(unsigned char)(U1(p+1)*4.0+0.5);
raw->obs.data[n].P[0] =(ind&0x1)?R8(p+ 2):0.0;
raw->obs.data[n].L[0] =(ind&0x4)?R8(p+10):0.0;
raw->obs.data[n].D[0] =(ind&0x2)?R4(p+18):0.0f;
raw->obs.data[n].LLI[0]=(ind&0x8)?1:0; /* slip */
raw->obs.data[n].code[0]=CODE_L1C;
/* receiver dependent options */
if (strstr(raw->opt,"-invcp")) {
raw->obs.data[n].L[0]=-raw->obs.data[n].L[0];
}
if (prn>MAXPRNGPS) prn+=MINPRNSBS-38;
if (!(sat=satno(MINPRNSBS<=prn?SYS_SBS:SYS_GPS,prn))) {
trace(2,"stq raw satellite number error: prn=%d\n",prn);
continue;
}
raw->obs.data[n].time=raw->time;
raw->obs.data[n].sat =sat;
for (j=1;j<NFREQ;j++) {
raw->obs.data[n].L[j]=raw->obs.data[n].P[j]=0.0;
raw->obs.data[n].D[j]=0.0;
raw->obs.data[n].SNR[j]=raw->obs.data[n].LLI[j]=0;
raw->obs.data[n].code[j]=CODE_NONE;
}
n++;
}
raw->obs.n=n;
return n>0?1:0;
}
/* save subframe -------------------------------------------------------------*/
static int save_subfrm(int sat, raw_t *raw)
{
unsigned char *p=raw->buff+7,*q;
int i,id;
trace(4,"save_subfrm: sat=%2d\n",sat);
/* check navigation subframe preamble */
if (p[0]!=0x8B) {
trace(2,"stq subframe preamble error: 0x%02X\n",p[0]);
return 0;
}
id=(p[5]>>2)&0x7;
/* check subframe id */
if (id<1||5<id) {
trace(2,"stq subframe id error: id=%d\n",id);
return 0;
}
q=raw->subfrm[sat-1]+(id-1)*30;
for (i=0;i<30;i++) q[i]=p[i];
return id;
}
/* decode ephemeris ----------------------------------------------------------*/
static int decode_ephem(int sat, raw_t *raw)
{
eph_t eph={0};
trace(4,"decode_ephem: sat=%2d\n",sat);
if (decode_frame(raw->subfrm[sat-1] ,&eph,NULL,NULL,NULL,NULL)!=1||
decode_frame(raw->subfrm[sat-1]+30,&eph,NULL,NULL,NULL,NULL)!=2||
decode_frame(raw->subfrm[sat-1]+60,&eph,NULL,NULL,NULL,NULL)!=3) return 0;
if (eph.iode==raw->nav.eph[sat-1].iode) return 0; /* unchanged */
eph.sat=sat;
raw->nav.eph[sat-1]=eph;
raw->ephsat=sat;
return 2;
}
/* decode almanac and ion/utc ------------------------------------------------*/
static int decode_alm1(int sat, raw_t *raw)
{
trace(4,"decode_alm1 : sat=%2d\n",sat);
decode_frame(raw->subfrm[sat-1]+90,NULL,raw->nav.alm,raw->nav.ion_gps,
raw->nav.utc_gps,&raw->nav.leaps);
return 0;
}
/* decode almanac ------------------------------------------------------------*/
static int decode_alm2(int sat, raw_t *raw)
{
trace(4,"decode_alm2 : sat=%2d\n",sat);
decode_frame(raw->subfrm[sat-1]+120,NULL,raw->nav.alm,NULL,NULL,NULL);
return 0;
}
/* decode skytraq subframe buffer --------------------------------------------*/
static int decode_stqsfrb(raw_t *raw)
{
int prn,sat,sys,id;
unsigned char *p=raw->buff+4;
trace(4,"decode_stqsfrb: len=%d\n",raw->len);
if (raw->len<40) {
trace(2,"stq subframe length error: len=%d\n",raw->len);
return -1;
}
prn=U1(p+1);
if (prn>MAXPRNGPS) prn+=MINPRNSBS-38;
if (!(sat=satno(MINPRNSBS<=prn?SYS_SBS:SYS_GPS,prn))) {
trace(2,"stq subframe satellite number error: prn=%d\n",prn);
return -1;
}
sys=satsys(sat,&prn);
if (sys==SYS_GPS) {
id=save_subfrm(sat,raw);
if (id==3) return decode_ephem(sat,raw);
if (id==4) return decode_alm1 (sat,raw);
if (id==5) return decode_alm2 (sat,raw);
return 0;
}
return 0;
}
/* decode skytraq message ----------------------------------------------------*/
static int decode_stq(raw_t *raw)
{
int type=U1(raw->buff+4);
unsigned char cs,*p=raw->buff+raw->len-3;
trace(3,"decode_stq: type=%02x len=%d\n",type,raw->len);
/* checksum */
cs=checksum(raw->buff,raw->len);
if (cs!=*p||*(p+1)!=0x0D||*(p+2)!=0x0A) {
trace(2,"stq checksum error: type=%02X cs=%02X tail=%02X%02X%02X\n",
type,cs,*p,*(p+1),*(p+2));
return -1;
}
sprintf(raw->msgtype,"SKYTRAQ: type=%02x len=%3d",type,raw->len);
switch (type) {
case ID_STQTIME: return decode_stqtime(raw);
case ID_STQRAW : return decode_stqraw (raw);
case ID_STQSFRB: return decode_stqsfrb(raw);
}
return 0;
}
/* sync code -----------------------------------------------------------------*/
static int sync_stq(unsigned char *buff, unsigned char data)
{
buff[0]=buff[1]; buff[1]=data;
return buff[0]==STQSYNC1&&buff[1]==STQSYNC2;
}
/* input skytraq raw message from stream ---------------------------------------
* fetch next skytraq raw data and input a mesasge from stream
* args : raw_t *raw IO receiver raw data control struct
* raw->opt : skytraq raw options
* "-invcp" : inversed polarity of carrier-phase
* unsigned char data I stream data (1 byte)
* return : status (-1: error message, 0: no message, 1: input observation data,
* 2: input ephemeris, 3: input sbas message,
* 9: input ion/utc parameter)
*-----------------------------------------------------------------------------*/
extern int input_stq(raw_t *raw, unsigned char data)
{
trace(5,"input_stq: data=%02x\n",data);
/* synchronize frame */
if (raw->nbyte==0) {
if (!sync_stq(raw->buff,data)) return 0;
raw->nbyte=2;
return 0;
}
raw->buff[raw->nbyte++]=data;
if (raw->nbyte==4) {
if ((raw->len=U2(raw->buff+2)+7)>MAXRAWLEN) {
trace(2,"stq message length error: len=%d\n",raw->len);
raw->nbyte=0;
return -1;
}
}
if (raw->nbyte<4||raw->nbyte<raw->len) return 0;
raw->nbyte=0;
/* decode skytraq raw message */
return decode_stq(raw);
}
/* input skytraq raw message from file -----------------------------------------
* fetch next skytraq raw data and input a message from file
* args : raw_t *raw IO receiver raw data control struct
* FILE *fp I file pointer
* return : status(-2: end of file, -1...9: same as above)
*-----------------------------------------------------------------------------*/
extern int input_stqf(raw_t *raw, FILE *fp)
{
int i,data;
trace(4,"input_stqf:\n");
/* synchronize frame */
if (raw->nbyte==0) {
for (i=0;;i++) {
if ((data=fgetc(fp))==EOF) return -2;
if (sync_stq(raw->buff,(unsigned char)data)) break;
if (i>=4096) return 0;
}
}
if (fread(raw->buff+2,1,2,fp)<2) return -2;
raw->nbyte=4;
if ((raw->len=U2(raw->buff+2)+7)>MAXRAWLEN) {
trace(2,"stq message length error: len=%d\n",raw->len);
raw->nbyte=0;
return -1;
}
if (fread(raw->buff+4,1,raw->len-4,fp)<(size_t)(raw->len-4)) return -2;
raw->nbyte=0;
/* decode skytraq raw message */
return decode_stq(raw);
}
/* generate skytraq binary message ---------------------------------------------
* generate skytraq binary message from message string
* args : char *msg I message string
* "RESTART [arg...]" system restart
* "CFG-SERI [arg...]" configure serial port propperty
* "CFG-FMT [arg...]" configure output message format
* "CFG-RATE [arg...]" configure binary measurement output rates
* unsigned char *buff O binary message
* return : length of binary message (0: error)
* note : see reference [1][2] for details.
*-----------------------------------------------------------------------------*/
extern int gen_stq(const char *msg, unsigned char *buff)
{
const char *hz[]={"1Hz","2Hz","4Hz","5Hz","10Hz","20Hz",""};
unsigned char *q=buff;
char mbuff[1024],*args[32],*p;
int i,n,narg=0;
trace(4,"gen_stq: msg=%s\n",msg);
strcpy(mbuff,msg);
for (p=strtok(mbuff," ");p&&narg<32;p=strtok(NULL," ")) {
args[narg++]=p;
}
*q++=STQSYNC1;
*q++=STQSYNC2;
if (!strcmp(args[0],"RESTART")) {
*q++=0;
*q++=15;
*q++=ID_RESTART;
*q++=narg>2?(unsigned char)atoi(args[1]):0;
for (i=1;i<15;i++) *q++=0; /* set all 0 */
}
else if (!strcmp(args[0],"CFG-SERI")) {
*q++=0;
*q++=4;
*q++=ID_CFGSERI;
for (i=1;i<4;i++) *q++=narg>i+1?(unsigned char)atoi(args[i]):0;
}
else if (!strcmp(args[0],"CFG-FMT")) {
*q++=0;
*q++=3;
*q++=ID_CFGFMT;
for (i=1;i<3;i++) *q++=narg>i+1?(unsigned char)atoi(args[i]):0;
}
else if (!strcmp(args[0],"CFG-RATE")) {
*q++=0;
*q++=8;
*q++=ID_CFGRATE;
if (narg>2) {
for (i=0;*hz[i];i++) if (!strcmp(args[1],hz[i])) break;
if (*hz[i]) *q++=i; else *q++=(unsigned char)atoi(args[1]);
}
else *q++=0;
for (i=2;i<8;i++) *q++=narg>i+1?(unsigned char)atoi(args[i]):0;
}
else return 0;
n=(int)(q-buff);
*q++=checksum(buff,n+3);
*q++=0x0D;
*q=0x0A;
return n+3;
}