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Make the sequence detector work for arbitrary frequency offsets. Assume drift=0 for now.

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git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@8396 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
This commit is contained in:
Steven Franke 2018-01-05 21:57:15 +00:00
parent 3ea288b97a
commit e8e2d57cc2
1 changed files with 21 additions and 10 deletions
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31
lib/wsprd/wsprd_exp.c
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@ -354,9 +354,9 @@ void noncoherent_sequence_detection(float *id, float *qd, long np,
int i, j, k, lag, k0, isign, itone, ib, b, nblock, nseq, imask;
float xi[512],xq[512];
float is[4][162],qs[4][162];
float is[4][162],qs[4][162],cf[4][162],sf[4][162],cm,sm,cmp,smp;
float p[512],totp,fac,xm1,xm0;
float c0[256],s0[256],c1[256],s1[256],c2[256],s2[256],c3[256],s3[256];
float c0[257],s0[257],c1[257],s1[257],c2[257],s2[257],c3[257],s3[257];
float dphi0, cdphi0, sdphi0, dphi1, cdphi1, sdphi1, dphi2, cdphi2, sdphi2,
dphi3, cdphi3, sdphi3;
float f0, fp, ss, fsum=0.0, f2sum=0.0, fsymb[162];
@ -366,7 +366,7 @@ void noncoherent_sequence_detection(float *id, float *qd, long np,
lag=*shift1;
nblock=*nblocksize;
nseq=1<<nblock;
for (i=0; i<162; i++) {
fp = f0 + (*drift1/2.0)*((float)i-81.0)/81.0;
if( i==0 || (fp != fplast) ) { // only calculate sin/cos if necessary
@ -391,7 +391,7 @@ void noncoherent_sequence_detection(float *id, float *qd, long np,
c2[0]=1; s2[0]=0;
c3[0]=1; s3[0]=0;
for (j=1; j<256; j++) {
for (j=1; j<257; j++) {
c0[j]=c0[j-1]*cdphi0 - s0[j-1]*sdphi0;
s0[j]=c0[j-1]*sdphi0 + s0[j-1]*cdphi0;
c1[j]=c1[j-1]*cdphi1 - s1[j-1]*sdphi1;
@ -401,9 +401,15 @@ void noncoherent_sequence_detection(float *id, float *qd, long np,
c3[j]=c3[j-1]*cdphi3 - s3[j-1]*sdphi3;
s3[j]=c3[j-1]*sdphi3 + s3[j-1]*cdphi3;
}
fplast = fp;
}
cf[0][i]=c0[256]; sf[0][i]=s0[256];
cf[1][i]=c1[256]; sf[1][i]=s1[256];
cf[2][i]=c2[256]; sf[2][i]=s2[256];
cf[3][i]=c3[256]; sf[3][i]=s3[256];
is[0][i]=0.0; qs[0][i]=0.0;
is[1][i]=0.0; qs[1][i]=0.0;
is[2][i]=0.0; qs[2][i]=0.0;
@ -427,13 +433,16 @@ void noncoherent_sequence_detection(float *id, float *qd, long np,
for (i=0; i<162; i=i+nblock) {
for (j=0;j<nseq;j++) {
xi[j]=0.0; xq[j]=0.0;
cm=1; sm=0;
isign=1;
for (ib=0; ib<nblock; ib++) {
b=(j&(1<<(nblock-1-ib)))>>(nblock-1-ib);
itone=pr3[i+ib]+2*b;
xi[j]=xi[j]+isign*is[itone][i+ib];
xq[j]=xq[j]+isign*qs[itone][i+ib];
isign=-isign;
xi[j]=xi[j]+is[itone][i+ib]*cm + qs[itone][i+ib]*sm;
xq[j]=xq[j]+qs[itone][i+ib]*cm - is[itone][i+ib]*sm;
cmp=cf[itone][i+ib]*cm - sf[itone][i+ib]*sm;
smp=sf[itone][i+ib]*cm + cf[itone][i+ib]*sm;
cm=cmp; sm=smp;
}
p[j]=xi[j]*xi[j]+xq[j]*xq[j];
p[j]=sqrt(p[j]);
@ -769,7 +778,8 @@ int main(int argc, char *argv[])
float minsync2=0.10; //Second sync limit
int iifac=8; //Step size in final DT peakup
int symfac=50; //Soft-symbol normalizing factor
int maxdrift=4; //Maximum (+/-) drift
// int maxdrift=4; //Maximum (+/-) drift
int maxdrift=0; //Maximum (+/-) drift
float minrms=52.0 * (symfac/64.0); //Final test for plausible decoding
delta=60; //Fano threshold step
float bias=0.45; //Fano metric bias (used for both Fano and stack algorithms)
@ -1188,6 +1198,7 @@ int main(int argc, char *argv[])
sync_and_demodulate(idat, qdat, npoints, symbols, &f1, ifmin, ifmax, fstep, &shift1,
lagmin, lagmax, lagstep, &drift1, symfac, &sync1, 1);
if(0) {
// refine drift estimate
fstep=0.0; ifmin=0; ifmax=0;
float driftp,driftm,syncp,syncm;
@ -1206,7 +1217,7 @@ int main(int argc, char *argv[])
drift1=driftm;
sync1=syncm;
}
}
tsync1 += (float)(clock()-t0)/CLOCKS_PER_SEC;
// fine-grid lag and freq search