SNR, P and L std, float storage

Store the SNR as a float, rather than a uint16_t, avoiding the scaling
and rounding at each access.

The comnav and tersus decoders were not even using the SNR_UNIT for
scaling, perhaps another encoding, but assume scaling is not need when
stored as a float.

Store the P and L std in the float format. Makes better use of the
input format, without lossly compression. Avoids having to do the
encoding and decoding to the compressed format at each use.

Implement the compressed encoding in RINEX input and output. Easier to
make changes in one location here, and avoids this lossy compression
on other paths.

This uses a little extra storage, but if this is an issue then it
might be better to abstract a compressed encoding into accessor
functions than to have this distributed to each use. The P and L std
might be made a compilation option.

ublox: decode_trkmeas is estimating Lstd so have it respect the
-RCVSTDS option.

unicore: was not initialising P and L std.

app/consapp/rtkrcv/rtkrcv.c

@@ -868,7 +868,7 @@ static void probserv(vt_t *vt, int nf)
         for (j=0;j<nf;j++) vt_printf(vt,"%13.3f",obs[i].P[j]);
         for (j=0;j<nf;j++) vt_printf(vt,"%14.3f",obs[i].L[j]);
         for (j=0;j<nf;j++) vt_printf(vt,"%8.1f" ,obs[i].D[j]);
-        for (j=0;j<nf;j++) vt_printf(vt,"%3.0f" ,obs[i].SNR[j]*SNR_UNIT);
+        for (j=0;j<nf;j++) vt_printf(vt,"%3.0f" ,obs[i].SNR[j]);
         for (j=0;j<nf;j++) vt_printf(vt,"%2d"   ,obs[i].LLI[j]);
         vt_printf(vt,"\n");
     }

app/qtapp/rtknavi_qt/mondlg.cpp

@@ -1066,7 +1066,7 @@ void MonitorDialog::showObservations()
             else ui->tWConsole->item(i, j++)->setText("-");
         }
         for (k = 0; k < NFREQ + nex; k++) {
-            if (obs[i].SNR[k]) ui->tWConsole->item(i, j++)->setText(QString::number(obs[i].SNR[k] * SNR_UNIT, 'f', 1));
+            if (obs[i].SNR[k]) ui->tWConsole->item(i, j++)->setText(QString::number(obs[i].SNR[k], 'f', 1));
             else ui->tWConsole->item(i, j++)->setText("-");
         }
         for (k = 0; k < NFREQ + nex; k++)

app/qtapp/rtkplot_qt/plotcmn.cpp

@@ -342,7 +342,7 @@ QColor Plot::observationColor(const obsd_t *obs, double az, double el, QVariant
         if (obs->L[freq-1] == 0.0 && obs->P[freq-1] == 0.0) {
             return Qt::black;
         }
-        color = snrColor(obs->SNR[freq-1] * SNR_UNIT);
+        color = snrColor(obs->SNR[freq-1]);
     } else {  // code
         for (i = 0; i < NFREQ + NEXOBS; i++) {
             if (!strcmp(code2obs(obs->code[i]), qPrintable(obstype.toString()))) break;
@@ -353,7 +353,7 @@ QColor Plot::observationColor(const obsd_t *obs, double az, double el, QVariant
         if (obs->L[i] == 0.0 && obs->P[i] == 0.0) {
             return Qt::black;
         }
-        color = snrColor(obs->SNR[i] * SNR_UNIT);
+        color = snrColor(obs->SNR[i]);
     }
 
     // check against elevation mask

app/qtapp/rtkplot_qt/plotdata.cpp

@@ -1032,7 +1032,7 @@ void Plot::saveSnrMp(const QString &file)
                 time2str(timeadd(gpst2utc(time), 9 * 3600.0), tstr, 1);
             }
             data = QString("%1 %2 %3 %4 %5 %6f\n").arg(tstr).arg(sat, 6).arg(azimuth[j] * R2D, 8, 'f', 1)
-                       .arg(elevation[j] * R2D, 8, 'f', 1).arg(observation.data[j].SNR[k] * SNR_UNIT, 9, 'f', 2).arg(!multipath[k] ? 0.0 : multipath[k][j], 10, 'f', 4);
+                       .arg(elevation[j] * R2D, 8, 'f', 1).arg(observation.data[j].SNR[k], 9, 'f', 2).arg(!multipath[k] ? 0.0 : multipath[k][j], 10, 'f', 4);
             fp.write(data.toLatin1());
         }
     }

app/qtapp/rtkplot_qt/plotdraw.cpp

@@ -1509,7 +1509,7 @@ void Plot::drawSky(QPainter &c, int level)
                     if (obs->P[j] == 0.0 && obs->L[j] == 0.0)
                         s += "-- ";
                     else
-                        s += QStringLiteral("%1 ").arg(obs->SNR[j] * SNR_UNIT, 2, 'f', 0, QChar('0'));
+                        s += QStringLiteral("%1 ").arg(obs->SNR[j], 2, 'f', 0, QChar('0'));
                 }
 
                 // LLI
@@ -1532,7 +1532,7 @@ void Plot::drawSky(QPainter &c, int level)
                 if (obs->P[freq - 1] == 0.0 && obs->L[freq - 1] == 0.0)
                     s += "---- ";
                 else
-                    s += QStringLiteral("%1 ").arg(obs->SNR[freq - 1] * SNR_UNIT, 4, 'f', 1);
+                    s += QStringLiteral("%1 ").arg(obs->SNR[freq - 1], 4, 'f', 1);
 
                 // LLI
                 if (obs->L[freq-1] == 0.0)
@@ -1554,7 +1554,7 @@ void Plot::drawSky(QPainter &c, int level)
                 if (obs->P[j] == 0.0 && obs->L[j] == 0.0)
                     s += "---- ";
                 else
-                    s += QStringLiteral("%1 ").arg(obs->SNR[j] * SNR_UNIT, 4, 'f', 1);
+                    s += QStringLiteral("%1 ").arg(obs->SNR[j], 4, 'f', 1);
 
                 // LLI
                 if (obs->L[j] == 0.0)
@@ -1861,12 +1861,12 @@ void Plot::drawSnr(QPainter &c, int level)
                         }
                         if (idx >= NFREQ + NEXOBS) continue;
                     }
-                    if (obs->SNR[idx] * SNR_UNIT <= 0.0) continue;  // skip negative SNR
+                    if (obs->SNR[idx] <= 0.0) continue;  // skip negative SNR
 
                     // calculate position
                     x[n] = timePosition(obs->time);
                     if (panel == 0) {  // SNR
-                        y[n] = obs->SNR[idx] * SNR_UNIT;
+                        y[n] = obs->SNR[idx];
                         col[n] = plotOptDialog->getMarkerColor(0, 4);
                     } else if (panel == 1) {  // multipath
                         if (!multipath[idx] || multipath[idx][j] == 0.0) continue;
@@ -1878,7 +1878,7 @@ void Plot::drawSnr(QPainter &c, int level)
                         if (simulatedObservation)
                             col[n] = sysColor(obs->sat);
                         else
-                            col[n] = snrColor(obs->SNR[idx] * SNR_UNIT);
+                            col[n] = snrColor(obs->SNR[idx]);
 
                         if (elevation[j] > 0.0 && elevation[j] < plotOptDialog->getElevationMask() * D2R) col[n] = plotOptDialog->getMarkerColor(0, 0);
                     }
@@ -2059,10 +2059,10 @@ void Plot::drawSnrE(QPainter &c, int level)
                     }
                     if (idx >= NFREQ + NEXOBS) continue;
                 }
-                if (obs->SNR[idx] * SNR_UNIT <= 0.0) continue;
+                if (obs->SNR[idx] <= 0.0) continue;
 
                 x[0][n[0]] = x[1][n[1]] = elevation[j] * R2D;
-                y[0][n[0]] = obs->SNR[idx] * SNR_UNIT;
+                y[0][n[0]] = obs->SNR[idx];
                 y[1][n[1]] = !multipath[idx] ? 0.0 : multipath[idx][j];
 
                 col[0][n[0]] = col[1][n[1]] = (elevation[j] > 0.0 && elevation[j] < plotOptDialog->getElevationMask() * D2R) ?\
@@ -2340,7 +2340,7 @@ void Plot::drawResidual(QPainter &c, int level)
                 y[0][m[0]] = solstat->resp;
                 y[1][m[1]] = solstat->resc;
                 y[2][m[2]] = solstat->el * R2D;
-                y[3][m[3]] = solstat->snr * SNR_UNIT;
+                y[3][m[3]] = solstat->snr;
 
                 if (!(solstat->flag >> 5)) q = 0;          // invalid
                 else if ((solstat->flag & 7) <= 1) q = 2;  // float

app/winapp/rtknavi/mondlg.cpp

@@ -1004,7 +1004,7 @@ void __fastcall TMonitorDialog::ShowObs(void)
 			else       Tbl->Cells[j++][i+1]="-";
 		}
 		for (k=0;k<NFREQ+nex;k++) {
-			if (obs[i].SNR[k]) Tbl->Cells[j++][i+1]=s.sprintf("%.1f",obs[i].SNR[k]*SNR_UNIT);
+			if (obs[i].SNR[k]) Tbl->Cells[j++][i+1]=s.sprintf("%.1f",obs[i].SNR[k]);
 			else               Tbl->Cells[j++][i+1]=s.sprintf("-");
 		}
 		for (k=0;k<NFREQ+nex;k++) {

app/winapp/rtkplot/plotcmn.cpp

@@ -342,7 +342,7 @@ TColor __fastcall TPlot::ObsColor(const obsd_t *obs, double az, double el)
         if (obs->L[freq-1]==0.0&&obs->P[freq-1]==0.0) {
             return clBlack;
         }
-        color=SnrColor(obs->SNR[freq-1]*SNR_UNIT);
+        color=SnrColor(obs->SNR[freq-1]);
     }
     else {
         for (i=0;i<NFREQ+NEXOBS;i++) {
@@ -354,7 +354,7 @@ TColor __fastcall TPlot::ObsColor(const obsd_t *obs, double az, double el)
         if (obs->L[i]==0.0&&obs->P[i]==0.0) {
             return clBlack;
         }
-        color=SnrColor(obs->SNR[i]*SNR_UNIT);
+        color=SnrColor(obs->SNR[i]);
     }
     if (el<ElMask*D2R||(ElMaskP&&el<ElMaskData[(int)(az*R2D+0.5)])) {
         return HideLowSat?clBlack:MColor[0][0];

app/winapp/rtkplot/plotdata.cpp

@@ -1047,7 +1047,7 @@ void __fastcall TPlot::SaveSnrMp(AnsiString file)
                 time2str(timeadd(gpst2utc(time),9*3600.0),tstr,1);
             }
             fprintf(fp,"%s %6s %8.1f %8.1f %9.2f %10.4f\n",tstr,sat,Az[j]*R2D,
-                    El[j]*R2D,Obs.data[j].SNR[k]*SNR_UNIT,!Mp[k]?0.0:Mp[k][j]);
+                    El[j]*R2D,Obs.data[j].SNR[k],!Mp[k]?0.0:Mp[k][j]);
         }
     }
     fclose(fp);

app/winapp/rtkplot/plotdraw.cpp

@@ -1346,7 +1346,7 @@ void __fastcall TPlot::DrawSky(int level)
                 ustr+=" ";
                 for (j=0;j<NFREQ;j++) {
                     if (obs->P[j]==0.0&&obs->L[j]==0.0) ustr+="-- ";
-                    else ustr+=ss.sprintf("%02.0f ",obs->SNR[j]*SNR_UNIT);
+                    else ustr+=ss.sprintf("%02.0f ",obs->SNR[j]);
                 }
                 for (j=0;j<NFREQ;j++) {
                     if (obs->L[j]==0.0) ustr+="-";
@@ -1360,7 +1360,7 @@ void __fastcall TPlot::DrawSky(int level)
                               obs->P[freq-1]==0.0?"-":"C",obs->L[freq-1]==0.0?"-":"L",
                               obs->D[freq-1]==0.0?"-":"D");
                 if (obs->P[freq-1]==0.0&&obs->L[freq-1]==0.0) ustr+="---- ";
-                else ustr+=ss.sprintf("%4.1f ",obs->SNR[freq-1]*SNR_UNIT);
+                else ustr+=ss.sprintf("%4.1f ",obs->SNR[freq-1]);
                 if (obs->L[freq-1]==0.0) ustr+=" -";
                 else ustr+=ss.sprintf("%2d",obs->LLI[freq-1]);
             }
@@ -1373,7 +1373,7 @@ void __fastcall TPlot::DrawSky(int level)
                                  obs->P[j]==0.0?"-":"C",obs->L[j]==0.0?"-":"L",
                                  obs->D[j]==0.0?"-":"D");
                 if (obs->P[j]==0.0&&obs->L[j]==0.0) ustr+="---- ";
-                else ustr+=ss.sprintf("%4.1f ",obs->SNR[j]*SNR_UNIT);
+                else ustr+=ss.sprintf("%4.1f ",obs->SNR[j]);
                 if (obs->L[j]==0.0) ustr+=" -";
                 else ustr+=ss.sprintf("%2d",obs->LLI[j]);
             }
@@ -1644,11 +1644,11 @@ void __fastcall TPlot::DrawSnr(int level)
                         }
                         if (k>=NFREQ+NEXOBS) continue;
                     }
-                    if (obs->SNR[k]*SNR_UNIT<=0.0) continue;
+                    if (obs->SNR[k]<=0.0) continue;
 
                     x[n]=TimePos(obs->time);
                     if (i==0) {
-                        y[n]=obs->SNR[k]*SNR_UNIT;
+                        y[n]=obs->SNR[k];
                         col[n]=MColor[0][4];
                     }
                     else if (i==1) {
@@ -1659,7 +1659,7 @@ void __fastcall TPlot::DrawSnr(int level)
                     else {
                         y[n]=El[j]*R2D;
                         if (SimObs) col[n]=SysColor(obs->sat);
-                        else col[n]=SnrColor(obs->SNR[k]*SNR_UNIT);
+                        else col[n]=SnrColor(obs->SNR[k]);
                         if (El[j]>0.0&&El[j]<ElMask*D2R) col[n]=MColor[0][0];
                     }
                     if (timediff(time,obs->time)==0.0&&np<MAXSAT) {
@@ -1801,10 +1801,10 @@ void __fastcall TPlot::DrawSnrE(int level)
                     }
                     if (k>=NFREQ+NEXOBS) continue;
                 }
-                if (obs->SNR[k]*SNR_UNIT<=0.0) continue;
+                if (obs->SNR[k]<=0.0) continue;
 
                 x[0][n[0]]=x[1][n[1]]=El[j]*R2D;
-                y[0][n[0]]=obs->SNR[k]*SNR_UNIT;
+                y[0][n[0]]=obs->SNR[k];
                 y[1][n[1]]=!Mp[k]?0.0:Mp[k][j];
 
                 col[0][n[0]]=col[1][n[1]]=
@@ -2042,7 +2042,7 @@ void __fastcall TPlot::DrawRes(int level)
                 y[0][m[0]]=p->resp;
                 y[1][m[1]]=p->resc;
                 y[2][m[2]]=p->el*R2D;
-                y[3][m[3]]=p->snr*SNR_UNIT;
+                y[3][m[3]]=p->snr;
                 if      (!(p->flag>>5))  q=0; // invalid
                 else if ((p->flag&7)<=1) q=2; // float
                 else if ((p->flag&7)<=3) q=1; // fixed

src/pntpos.c

@@ -65,12 +65,12 @@ static double varerr(const prcopt_t *opt, const ssat_t *ssat, const obsd_t *obs,
     /* var = R^2*(a^2 + (b^2/sin(el) + c^2*(10^(0.1*(snr_max-snr_rover)))) + (d*rcv_std)^2) */
     varr=SQR(opt->err[1])+SQR(opt->err[2])/sin(el);
     if (opt->err[6]>0.0) {  /* if snr term not zero */
-        snr_rover=(ssat)?SNR_UNIT*ssat->snr_rover[0]:opt->err[5];
+        snr_rover=(ssat)?ssat->snr_rover[0]:opt->err[5];
         varr+=SQR(opt->err[6])*pow(10,0.1*MAX(opt->err[5]-snr_rover,0));
     }
     varr*=SQR(opt->eratio[0]);
     if (opt->err[7]>0.0) {
-        varr+=SQR(opt->err[7]*0.01*(1<<(obs->Pstd[0]+5)));  /* 0.01*2^(n+5) m */
+        varr+=SQR(opt->err[7]*obs->Pstd[0]);
     }
     if (opt->ionoopt==IONOOPT_IFLC) varr*=SQR(3.0); /* iono-free */
     return SQR(fact)*varr;
@@ -98,12 +98,12 @@ static int snrmask(const obsd_t *obs, const double *azel, const prcopt_t *opt)
 {
     int f2;
 
-    if (testsnr(0,0,azel[1],obs->SNR[0]*SNR_UNIT,&opt->snrmask)) {
+    if (testsnr(0,0,azel[1],obs->SNR[0],&opt->snrmask)) {
         return 0;
     }
     if (opt->ionoopt==IONOOPT_IFLC) {
         f2=seliflc(opt->nf,satsys(obs->sat,NULL));
-        if (testsnr(0,f2,azel[1],obs->SNR[f2]*SNR_UNIT,&opt->snrmask)) return 0;
+        if (testsnr(0,f2,azel[1],obs->SNR[f2],&opt->snrmask)) return 0;
     }
     return 1;
 }

src/ppp.c

@@ -360,8 +360,8 @@ static double varerr(int sat, int sys, double el, double snr_rover,
         var+=e*e*(pow(10,0.1*MAX(snr_max-snr_rover,0)));
     }
     if (opt->err[7]>0.0) {   /* add rcvr stdevs term */
-        if (code) var+=SQR(opt->err[7]*0.01*(1<<(obs->Pstd[frq]+5))); /* 0.01*2^(n+5) */
-        else var+=SQR(opt->err[7]*obs->Lstd[frq]*0.004*0.2); /* 0.004 cycles -> m) */
+        if (code) var+=SQR(opt->err[7]*obs->Pstd[frq]);
+        else var+=SQR(opt->err[7]*obs->Lstd[frq]*0.2);
     }
     /* FIXME: the scaling factor is not 3 for other signals/constellations than GPS L1/L2 */
     var*=(opt->ionoopt==IONOOPT_IFLC)?SQR(3.0):1.0;
@@ -414,7 +414,7 @@ static void corr_meas(const obsd_t *obs, const nav_t *nav, const double *azel,
         /* skip if low SNR or missing observations */
         freq[i]=sat2freq(obs->sat,obs->code[i],nav);
         if (freq[i]==0.0||obs->L[i]==0.0||obs->P[i]==0.0) continue;
-        if (testsnr(0,0,azel[1],obs->SNR[i]*SNR_UNIT,&opt->snrmask)) continue;
+        if (testsnr(0,0,azel[1],obs->SNR[i],&opt->snrmask)) continue;
 
         /* antenna phase center and phase windup correction */
         L[i]=obs->L[i]*CLIGHT/freq[i]-dants[i]-dantr[i]-phw*CLIGHT/freq[i];
@@ -1045,7 +1045,7 @@ static int ppp_res(int post, const obsd_t *obs, int n, const double *rs,
 
             /* variance */
             var[nv]=varerr(sat,sys,azel[1+i*2],
-                    SNR_UNIT*rtk->ssat[sat-1].snr_rover[frq],
+                    rtk->ssat[sat-1].snr_rover[frq],
                     j,opt,obs+i);
             var[nv] +=vart+SQR(C)*vari+var_rs[i];
             if (sys==SYS_GLO&&code==1) var[nv]+=VAR_GLO_IFB;

src/rcv/binex.c

@@ -976,16 +976,16 @@ static uint8_t *decode_bnx_7f_05_obs(raw_t *raw, uint8_t *buff, int sat,
         }
         if (k<0) {
             data->P[i]=data->L[i]=0.0;
-            data->D[i]=0.0f;
-            data->SNR[i]=data->LLI[i]=0;
+            data->D[i]=data->SNR[i]=0.0;
+            data->LLI[i]=0;
             data->code[i]=CODE_NONE;
         }
         else {
             freq=code2freq(sys,codes[code[k]],fcn);
             data->P[i]=range[k];
             data->L[i]=phase[k]*freq/CLIGHT;
             data->D[i]=dopp[k];
-            data->SNR[i]=(uint16_t)(cnr[k]/SNR_UNIT+0.5);
+            data->SNR[i]=cnr[k];
             data->code[i]=codes[code[k]];
             data->LLI[i]=slip[k]?1:0;
             mask[k]=1;
@@ -997,16 +997,16 @@ static uint8_t *decode_bnx_7f_05_obs(raw_t *raw, uint8_t *buff, int sat,
         }
         if (k>=nobs) {
             data->P[i]=data->L[i]=0.0;
-            data->D[i]=0.0f;
-            data->SNR[i]=data->LLI[i]=0;
+            data->D[i]=data->SNR[i]=0.0;
+            data->LLI[i]=0;
             data->code[i]=CODE_NONE;
         }
         else {
             freq=code2freq(sys,codes[code[k]],fcn);
             data->P[i]=range[k];
             data->L[i]=phase[k]*freq/CLIGHT;
             data->D[i]=dopp[k];
-            data->SNR[i]=(uint16_t)(cnr[k]/SNR_UNIT+0.5);
+            data->SNR[i]=cnr[k];
             data->code[i]=codes[code[k]];
             data->LLI[i]=slip[k]?1:0;
             mask[k]=1;

src/rcv/comnav.c

@@ -84,8 +84,8 @@ static int obsindex(obs_t *obs, gtime_t time, int sat)
     obs->data[i].sat=sat;
     for (j=0;j<NFREQ+NEXOBS;j++) {
         obs->data[i].L[j]=obs->data[i].P[j]=0.0;
-        obs->data[i].D[j]=0.0;
-        obs->data[i].SNR[j]=obs->data[i].LLI[j]=0;
+        obs->data[i].D[j]=obs->data[i].SNR[j]=0.0;
+        obs->data[i].LLI[j]=0;
         obs->data[i].code[j]=CODE_NONE;
     }
     obs->n++;
@@ -299,8 +299,7 @@ static int decode_rangecmpb(raw_t *raw)
             raw->obs.data[index].L  [pos]=adr;
             raw->obs.data[index].P  [pos]=psr;
             raw->obs.data[index].D  [pos]=(float)dop;
-            raw->obs.data[index].SNR[pos]=
-                0.0<=snr&&snr<255.0?(unsigned char)(snr*4.0+0.5):0;
+            raw->obs.data[index].SNR[pos]=0.0<=snr&&snr<255.0?snr:0;
             raw->obs.data[index].LLI[pos]=(unsigned char)lli;
             raw->obs.data[index].code[pos]=code;
 #if 0
@@ -388,8 +387,7 @@ static int decode_rangeb(raw_t *raw)
             raw->obs.data[index].L  [pos]=-adr;
             raw->obs.data[index].P  [pos]=psr;
             raw->obs.data[index].D  [pos]=(float)dop;
-            raw->obs.data[index].SNR[pos]=
-                0.0<=snr&&snr<255.0?(unsigned char)(snr*4.0+0.5):0;
+            raw->obs.data[index].SNR[pos]=0.0<=snr&&snr<255.0?snr:0;
             raw->obs.data[index].LLI[pos]=(unsigned char)lli;
             raw->obs.data[index].code[pos]=code;
 #if 0