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In subtractft8.f90: refine DT for early decodes before subtracting them from dd().
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Joe Taylor
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1d159a18c7
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ff46c5a0c4
@ -418,7 +418,7 @@ subroutine ft8b(dd0,newdat,nQSOProgress,nfqso,nftx,ndepth,nzhsym,lapon, &
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endif
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nbadcrc=0 ! If we get this far: valid codeword, valid (i3,n3), nonquirky message.
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call get_ft8_tones_from_77bits(message77,itone)
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if(lsubtract) call subtractft8(dd0,itone,f1,xdt)
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if(lsubtract) call subtractft8(dd0,itone,f1,xdt,.false.)
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! write(21,3001) nzhsym,npasses,nqsoprogress,ipass,iaptype,lsubtract, &
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! f1,xdt,msg37(1:22); flush(21)
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!3001 format(5i3,L3,f7.1,f7.2,2x,a22)
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@ -1,66 +1,113 @@
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subroutine subtractft8(dd,itone,f0,dt)
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subroutine subtractft8(dd0,itone,f0,dt,ldt)
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! Subtract an ft8 signal
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!
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! Measured signal : dd(t) = a(t)cos(2*pi*f0*t+theta(t))
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! Subtract an ft8 signal. If ldt==.true., refine DT first.
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! Raw data : dd(t) = a(t)cos(2*pi*f0*t+theta(t))
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! Reference signal : cref(t) = exp( j*(2*pi*f0*t+phi(t)) )
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parameter (NMAX=15*12000,NFRAME=1920*79)
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real dd(NMAX),dd0(NMAX)
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complex cref(NFRAME)
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logical ldt
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! Generate complex reference waveform
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call gen_ft8wave(itone,79,1920,2.0,12000.0,f0,cref,xjunk,1,NFRAME)
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if(ldt) then !Are we refining DT ?
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sqa=sqf(dd0,cref,f0,dt,ldt,-300,dd) !Yes
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sqb=sqf(dd0,cref,f0,dt,ldt,300,dd)
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endif
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sq0=sqf(dd0,cref,f0,dt,ldt,0,dd) !Do the subtraction with idt=0
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if(ldt) then
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call peakup(sqa,sq0,sqb,dx)
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if(abs(dx).gt.1.0) goto 100 !No acceptable minimum: do not subtract
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i1=nint(300.0*dx) !First approximation of better idt
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sqa=sqf(dd0,cref,f0,dt,ldt,i1-60,dd)
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sqb=sqf(dd0,cref,f0,dt,ldt,i1+60,dd)
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sq0=sqf(dd0,cref,f0,dt,ldt,i1,dd)
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call peakup(sqa,sq0,sqb,dx)
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if(abs(dx).gt.1.0) then !No acceptable minimum
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sq0=sqf(dd0,cref,f0,dt,ldt,0,dd) !Use idt=0 for subtraction
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go to 100
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endif
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i2=nint(60.0*dx) + i1 !Best estimate of idt
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sq0=sqf(dd0,cref,f0,dt,ldt,i2,dd) !Do the subtraction with idt=i2
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endif
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100 dd0=dd !Return dd0 with signal subtracted
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return
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end subroutine subtractft8
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real function sqf(dd0,cref,f0,dt,ldt,idt,dd)
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! Raw data : dd0(t) = a(t)cos(2*pi*f0*t+theta(t))
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! Reference signal : cref(t) = exp( j*(2*pi*f0*t+phi(t)) )
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! Complex amp : cfilt(t) = LPF[ dd(t)*CONJG(cref(t)) ]
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! Subtract : dd(t) = dd(t) - 2*REAL{cref*cfilt}
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use timer_module, only: timer
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! Subtract : dd(t) = dd0(t) - 2*REAL{cref*cfilt}
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parameter (NMAX=15*12000,NFRAME=1920*79)
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parameter (NFFT=NMAX,NFILT=1400)
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real*4 dd(NMAX), window(-NFILT/2:NFILT/2), xjunk
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complex cref,camp,cfilt,cw
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integer itone(79)
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logical first
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parameter (NFFT=NMAX,NFILT=2800)
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real dd(NMAX),dd0(NMAX)
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real window(-NFILT/2:NFILT/2)
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real x(NFFT+2)
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complex cx(0:NFFT/2),cref(NFRAME)
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complex camp,cfilt,cw,z
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logical first,ldt
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data first/.true./
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common/heap8/cref(NFRAME),camp(NMAX),cfilt(NMAX),cw(NMAX),xjunk(NFRAME)
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save first
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nstart=dt*12000+1
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nsym=79
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nsps=1920
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fs=12000.0
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icmplx=1
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bt=2.0
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call gen_ft8wave(itone,nsym,nsps,bt,fs,f0,cref,xjunk,icmplx,NFRAME)
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camp=0.
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do i=1,nframe
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id=nstart-1+i
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if(id.ge.1.and.id.le.NMAX) camp(i)=dd(id)*conjg(cref(i))
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enddo
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common/heap8/camp(NMAX),cfilt(NMAX),cw(NMAX)
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equivalence (x,cx)
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save first,/heap8/
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if(first) then
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! Create and normalize the filter
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pi=4.0*atan(1.0)
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fac=1.0/float(nfft)
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sum=0.0
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sumw=0.0
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do j=-NFILT/2,NFILT/2
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window(j)=cos(pi*j/NFILT)**2
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sum=sum+window(j)
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sumw=sumw+window(j)
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enddo
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cw=0.
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cw(1:NFILT+1)=window/sum
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cw(1:NFILT+1)=window/sumw
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cw=cshift(cw,NFILT/2+1)
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call four2a(cw,nfft,1,-1,1)
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cw=cw*fac
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first=.false.
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endif
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cfilt=0.0
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nstart=dt*12000+1 + idt
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camp=0.
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dd=dd0
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do i=1,nframe
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j=nstart-1+i
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if(j.ge.1.and.j.le.NMAX) camp(i)=dd(j)*conjg(cref(i))
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enddo
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cfilt(1:nframe)=camp(1:nframe)
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cfilt(nframe+1:)=0.0
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call four2a(cfilt,nfft,1,-1,1)
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cfilt(1:nfft)=cfilt(1:nfft)*cw(1:nfft)
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call four2a(cfilt,nfft,1,1,1)
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! Subtract the reconstructed signal
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x=0.
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do i=1,nframe
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j=nstart+i-1
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if(j.ge.1 .and. j.le.NMAX) dd(j)=dd(j)-2*REAL(cfilt(i)*cref(i))
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if(j.ge.1 .and. j.le.NMAX) then
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z=cfilt(i)*cref(i)
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dd(j)=dd(j)-2.0*real(z) !Subtract the reconstructed signal
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x(i)=dd(j)
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endif
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enddo
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sq=0.
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if(ldt) then
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call four2a(cx,NFFT,1,-1,0) !Forward FFT, r2c
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df=12000.0/NFFT
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ia=(f0-1.5*6.25)/df
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ib=(f0+8.5*6.25)/df
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do i=ia,ib
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sq=sq + real(cx(i))*real(cx(i)) + aimag(cx(i))*aimag(cx(i))
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enddo
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endif
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sqf=sq
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return
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end subroutine subtractft8
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end function sqf
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@ -77,7 +77,7 @@ contains
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endif
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if(nzhsym.eq.50 .and. ndec_early.ge.1) then
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do i=1,ndec_early
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call subtractft8(dd,itone_save(1,i),f1_save(i),xdt_save(i))
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call subtractft8(dd,itone_save(1,i),f1_save(i),xdt_save(i),.true.)
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enddo
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endif
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ifa=nfa
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