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https://github.com/saitohirga/WSJT-X.git
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Use complex signal for fine sync and symbol demod. Lower sync threshold. Improved SNR estimate.
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@7757 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
This commit is contained in:
Steven Franke
parent
2687a308d6
commit
304cbaa672
@ -7,4 +7,4 @@ parameter (NSPS=2048) !Samples per symbol at 12000 S/s
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parameter (NZ=NSPS*NN) !Samples in full 15 s waveform (161,792)
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parameter (NMAX=15*12000) !Samples in iwave (180,000)
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parameter (NFFT1=2*NSPS, NH1=NFFT1/2) !Length of FFTs for symbol spectra
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parameter (NHSYM=2*NMAX/NSPS-1) !Number of symbol spectra (half-symbol steps)
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parameter (NHSYM=2*NMAX/NH1-1) !Number of symbol spectra (1/2-symbol steps)
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@ -1,37 +1,134 @@
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subroutine ft8b(s,nfqso,f1,xdt,nharderrors,dmin,nbadcrc,message)
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subroutine ft8b(dd0,s,nfqso,f1,xdt,nharderrors,dmin,nbadcrc,message,xsnr)
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use timer_module, only: timer
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include 'ft8_params.f90'
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parameter(NRECENT=10)
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parameter(NRECENT=10,NP2=2812)
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character*12 recent_calls(NRECENT)
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character message*22
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character message*22,msgsent*22
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real a(5)
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real s(NH1,NHSYM)
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real s1(0:7,ND)
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real s1(0:7,ND),s2(0:7,NN)
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real ps(0:7)
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real rxdata(3*ND),llr(3*ND) !Soft symbols
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real dd0(15*12000)
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integer*1 decoded(KK),apmask(3*ND),cw(3*ND)
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integer itone(NN)
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integer icos7(0:6)
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complex cd0(NP2)
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complex csync(0:6,32)
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complex ctwk(32)
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complex csymb(32)
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logical first
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data icos7/2,5,6,0,4,1,3/
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data first/.true./
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save first,twopi,fs2,dt2,taus,baud,csync
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if( first ) then
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twopi=8.0*atan(1.0)
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fs2=12000.0/64.0
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dt2=1/fs2
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taus=32*dt2
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baud=1/taus
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do i=0,6
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phi=0.0
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dphi=twopi*icos7(i)*baud*dt2
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do j=1,32
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csync(i,j)=cmplx(cos(phi),sin(phi))
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phi=mod(phi+dphi,twopi)
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enddo
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enddo
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first=.false.
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endif
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max_iterations=40
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norder=2
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! if(abs(nfqso-f1).lt.10.0) norder=3
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tstep=0.5*NSPS/12000.0
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df=12000.0/NFFT1
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call ft8_downsample(dd0,f1,cd0)
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i0=max(1,nint(f1/df))
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j0=nint(xdt/tstep)
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i0=xdt*fs2
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smax=0.0
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do idt=i0-16,i0+16
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sync=0
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do i=0,6
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i1=idt+i*32
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i2=i1+36*32
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i3=i1+72*32
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term1=0.0 ! this needs to be fixed...
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term2=0.0
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term3=0.0
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if( i1.ge.1 .and. i1+31.le.NP2 ) &
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term1=abs(sum(cd0(i1:i1+31)*conjg(csync(i,1:32))))
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if( i2.ge.1 .and. i2+31.le.NP2 ) &
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term2=abs(sum(cd0(i2:i2+31)*conjg(csync(i,1:32))))
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if( i3.ge.1 .and. i3+31.le.NP2 ) &
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term3=abs(sum(cd0(i3:i3+31)*conjg(csync(i,1:32))))
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sync=sync+term1+term2+term3
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enddo
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if( sync .gt. smax ) then
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smax=sync
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ibest=idt
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delfbest=delf
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ifbest=if
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endif
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enddo
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xdt2=ibest*dt2
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! peak up the frequency
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i0=xdt2*fs2
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smax=0.0
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do ifr=-5,5
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delf=ifr*0.5
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dphi=twopi*delf*dt2
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phi=0.0
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do i=1,32
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ctwk(i)=cmplx(cos(phi),sin(phi))
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phi=mod(phi+dphi,twopi)
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enddo
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sync=0.0
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do i=0,6
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i1=i0+i*32
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i2=i1+36*32
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i3=i1+72*32
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term1=0.0 ! this needs to be fixed...
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term2=0.0
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term3=0.0
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if( i1.ge.1 .and. i1+31.le.NP2 ) &
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term1=abs(sum(cd0(i1:i1+31)*conjg(ctwk*csync(i,1:32))))
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if( i2.ge.1 .and. i2+31.le.NP2 ) &
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term2=abs(sum(cd0(i2:i2+31)*conjg(ctwk*csync(i,1:32))))
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if( i3.ge.1 .and. i3+31.le.NP2 ) &
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term3=abs(sum(cd0(i3:i3+31)*conjg(ctwk*csync(i,1:32))))
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sync=sync+term1+term2+term3
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enddo
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if( sync .gt. smax ) then
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smax=sync
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delfbest=delf
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endif
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enddo
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a=0.0
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a(1)=-delfbest
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call twkfreq1(cd0,NP2,fs2,a,cd0)
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xdt=xdt2
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f1=f1+delfbest
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j=0
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ia=i0
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ib=i0+14
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do k=1,NN
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if(k.le.7) cycle
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if(k.ge.37 .and. k.le.43) cycle
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if(k.gt.72) cycle
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n=j0+2*(k-1)+1
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if(n.lt.1) cycle
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j=j+1
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s1(0:7,j)=s(ia:ib:2,n)
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enddo
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i1=ibest+(k-1)*32
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csymb=cd0(i1:i1+31)
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call four2a(csymb,32,1,-1,1)
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s2(0:7,k)=abs(csymb(1:8))
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enddo
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j=0
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do k=1,NN
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if(k.le.7) cycle
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if(k.ge.37 .and. k.le.43) cycle
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if(k.gt.72) cycle
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j=j+1
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s1(0:7,j)=s2(0:7,k)
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enddo
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do j=1,ND
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ps=s1(0:7,j)
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where (ps.gt.0.0) ps=log(ps)
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@ -56,9 +153,6 @@ subroutine ft8b(s,nfqso,f1,xdt,nharderrors,dmin,nbadcrc,message)
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llr=2.0*rxdata/(ss*ss)
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apmask=0
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cw=0
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! cw will be needed for subtraction.
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! dmin is the correlation discrepancy of a returned codeword - it is
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! used to select the best codeword within osd174.
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call timer('bpd174 ',0)
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call bpdecode174(llr,apmask,max_iterations,decoded,cw,nharderrors)
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call timer('bpd174 ',1)
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@ -67,17 +161,62 @@ subroutine ft8b(s,nfqso,f1,xdt,nharderrors,dmin,nbadcrc,message)
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call timer('osd174 ',0)
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call osd174(llr,norder,decoded,cw,nharderrors,dmin)
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call timer('osd174 ',1)
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! This threshold needs to be tuned. 99.0 should pass everything.
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if( dmin .gt. 99.0 ) nharderrors=-1
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endif
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nbadcrc=1
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message=' '
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xsnr=-99.0
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if(count(cw.eq.0).eq.174) go to 900 !Reject the all-zero codeword
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if(nharderrors.ge.0) call chkcrc12a(decoded,nbadcrc)
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if( nharderrors.ge.0 .and. dmin.le.30.0 .and. nharderrors .lt. 30) then
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call chkcrc12a(decoded,nbadcrc)
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else
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nharderrors=-1
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go to 900
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endif
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if(nbadcrc.eq.0) then
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call extractmessage174(decoded,message,ncrcflag,recent_calls,nrecent)
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call genft8(message,msgsent,itone)
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xsig=0.0
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xnoi=0.0
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do i=1,79
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xsig=xsig+s2(itone(i),i)**2
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ios=mod(itone(i)+4,7)
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xnoi=xnoi+s2(ios,i)**2
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enddo
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xsnr=xsig/xnoi-1.0
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if( xsnr .lt. 0.0 ) xsnr=0.005
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xsnr=10.0*log10(xsnr)-26.3
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endif
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900 continue
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return
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end subroutine ft8b
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subroutine ft8_downsample(dd,f0,c1)
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! Downconvert to complex data sampled at 187.5 Hz, 32 samples/symbol
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parameter (NMAX=15*12000,NFFT2=2812)
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complex c1(0:NFFT2-1)
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complex cx(0:NMAX/2-1)
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real dd(NMAX),x(NMAX)
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equivalence (x,cx)
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df=12000.0/NMAX
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x=dd
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call four2a(x,NMAX,1,-1,0) !r2c FFT to freq domain
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baud=12000.0/(32.0*64.0)
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i0=nint(f0/df)
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ft=f0+8.0*baud
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it=nint(ft/df)
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fb=f0-1.0*baud
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ib=nint(fb/df)
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k=0
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c1=cmplx(0.0,0.0)
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do i=ib,it
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c1(k)=cx(i)
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k=k+1
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enddo
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c1=cshift(c1,i0-ib)
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call four2a(c1,NFFT2,1,1,1) !c2c FFT back to time domain
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c1=c1/(NMAX*NFFT2)
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return
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end subroutine ft8_downsample
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@ -58,7 +58,7 @@ program ft8sim
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f0=(isig+2)*100.0
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phi=0.0
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k=-1 + nint(xdt/dt)
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do j=1,NN !Generate complex waveform
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do j=1,NN !Generate complex waveform
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dphi=twopi*(f0+itone(j)*baud)*dt
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if(k.eq.0) phi=-dphi
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do i=1,NSPS
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@ -69,12 +69,12 @@ program ft8sim
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if(k.ge.0 .and. k.lt.NMAX) c0(k)=cmplx(cos(xphi),sin(xphi))
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enddo
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enddo
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if(fspread.ne.0.0 .or. delay.ne.0.0) call watterson(c,NZ,fs,delay,fspread)
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if(fspread.ne.0.0 .or. delay.ne.0.0) call watterson(c,NMAX,fs,delay,fspread)
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c=c+c0
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enddo
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c=c*sig
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if(snrdb.lt.90) then
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do i=0,NZ-1 !Add gaussian noise at specified SNR
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do i=0,NMAX-1 !Add gaussian noise at specified SNR
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xnoise=gran()
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ynoise=gran()
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c(i)=c(i) + cmplx(xnoise,ynoise)
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@ -85,7 +85,6 @@ program ft8sim
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rms=100.0
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if(snrdb.ge.90.0) iwave(1:NMAX)=nint(fac*real(c))
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if(snrdb.lt.90.0) iwave(1:NMAX)=nint(rms*real(c))
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iwave(NZ+1:)=0
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h=default_header(12000,NMAX)
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write(fname,1102) ifile
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@ -80,7 +80,7 @@ subroutine sync8(iwave,nfa,nfb,nfqso,s,candidate,ncand)
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candidate0=0.
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k=0
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syncmin=4.0
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syncmin=1.5
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do i=1,100
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n=ia + indx(iz+1-i) - 1
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if(red(n).lt.syncmin) exit
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@ -33,10 +33,11 @@ contains
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real ss(1,1) !### dummy, to be removed ###
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real s(NH1,NHSYM)
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real candidate(3,100)
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real dd(15*12000)
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logical, intent(in) :: newdat, nagain
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integer*2 iwave(15*12000)
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character datetime*13,message*22
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this%callback => callback
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write(datetime,1001) nutc !### TEMPORARY ###
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1001 format("000000_",i6.6)
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@ -45,7 +46,8 @@ contains
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call sync8(iwave,nfa,nfb,nfqso,s,candidate,ncand)
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call timer('sync8 ',1)
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syncmin=4.0
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dd=iwave
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syncmin=2.0
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! rewind 51
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do icand=1,ncand
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sync=candidate(3,icand)
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@ -54,13 +56,15 @@ contains
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xdt=candidate(2,icand)
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nsnr=min(99,nint(10.0*log10(sync) - 25.5)) !### empirical ###
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call timer('ft8b ',0)
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call ft8b(s,nfqso,f1,xdt,nharderrors,dmin,nbadcrc,message)
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call ft8b(dd,s,nfqso,f1,xdt,nharderrors,dmin,nbadcrc,message,xsnr)
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nsnr=xsnr
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xdt=xdt-0.6
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call timer('ft8b ',1)
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if (associated(this%callback)) call this%callback(sync,nsnr,xdt, &
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f1,nbadcrc,message)
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! write(*,'(f7.2,i5,f7.2,f9.1,i5,f7.2,2x,a22)') sync,nsnr,xdt,f1,nharderrors,dmin,message
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! write(13,1110) datetime,0,nsnr,xdt,f1,nharderrors,dmin,message
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!1110 format(a13,2i4,f6.2,f7.1,i4,' ~ ',f6.2,2x,a22,' FT8')
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1110 format(a13,2i4,f6.2,f7.1,i4,' ~ ',f6.2,2x,a22,' FT8')
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! write(51,3051) xdt,f1,sync,dmin,nsnr,nharderrors,nbadcrc,message
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!3051 format(4f9.1,3i5,2x,a22)
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! flush(51)
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