mirror of https://github.com/saitohirga/WSJT-X.git
178 lines
5.7 KiB
Fortran
178 lines
5.7 KiB
Fortran
subroutine short65(data,jz,NFreeze,MouseDF,DFTolerance,
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+ mode65,nspecialbest,nstest,dfsh,iderrbest,idriftbest,
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+ snrdb,ss1,ss2,nwsh)
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C Checks to see if this might be a shorthand message.
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C This is done before zapping, downsampling, or normal decoding.
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parameter (NP2=60*11025) !Size of data array
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parameter (NFFT=16384) !FFT length
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parameter (NH=NFFT/2) !Step size
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parameter (NQ=NFFT/4) !Saved spectral points
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parameter (MAXSTEPS=60*11025/NH) !Max # of steps
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real data(jz)
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integer DFTolerance
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real s2(NH,MAXSTEPS) !2d spectrum
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real ss(NQ,4) !Save spectra in four phase bins
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real psavg(NQ)
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real sigmax(4) !Peak of spectrum at each phase
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real ss1(-224:224) !Lower magenta curve
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real ss2(-224:224) !Upper magenta curve
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real ssavg(-10:10)
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integer ipk(4) !Peak bin at each phase
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save
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nspecialbest=0 !Default return value
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nstest=0
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df=11025.0/NFFT
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C Do 16 k FFTs, stepped by 8k. (*** Maybe should step by 4k? ***)
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call zero(psavg,NQ)
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nsteps=(jz-NH)/(4*NH)
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nsteps=4*nsteps !Number of steps
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do j=1,nsteps
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k=(j-1)*NH + 1
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call ps(data(k),NFFT,s2(1,j)) !Get power spectra
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call add(psavg,s2(1,j),psavg,NQ)
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enddo
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call flat1(psavg,s2,NQ,nsteps,NH,MAXSTEPS)
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nfac=40*mode65
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dtstep=0.5/df
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fac=dtstep/(60.0*df)
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C Define range of frequencies to be searched
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fa= 670.46
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fb=1870.46
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ia=fa/df
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ib=fb/df + 4.1*nfac !Upper tone is above sync tone by 4*nfac*df Hz
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if(ib.gt.NQ) ib=NQ
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if(NFreeze.eq.1) then
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fa=max( 670.46,1270.46+MouseDF-DFTolerance)
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fb=min(1870.46,1270.46+MouseDF+DFTolerance)
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endif
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ia2=fa/df
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ib2=fb/df + 4.1*nfac !Upper tone is above sync tone by 4*nfac*df Hz
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if(ib2.gt.NQ) ib2=NQ
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C Find strongest line in each of the 4 phases, repeating for each drift rate.
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sbest=0.
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snrbest=0.
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idz=6.0/df !Is this the right drift range?
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do idrift=-idz,idz
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drift=idrift*df*60.0/49.04
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call zero(ss,4*NQ) !Clear the accumulating array
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do j=1,nsteps
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n=mod(j-1,4)+1
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k=nint((j-nsteps/2)*drift*fac) + ia
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call add(ss(ia,n),s2(k,j),ss(ia,n),ib-ia+1)
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enddo
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do n=1,4
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sigmax(n)=0.
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do i=ia2,ib2
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sig=ss(i,n)
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if(sig.ge.sigmax(n)) then
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ipk(n)=i
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sigmax(n)=sig
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if(sig.ge.sbest) then
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sbest=sig
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nbest=n
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fdotsh=drift
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endif
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endif
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enddo
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enddo
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n2best=nbest+2
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if(n2best.gt.4) n2best=nbest-2
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xdf=min(ipk(nbest),ipk(n2best))*df - 1270.46
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if(NFreeze.eq.1 .and. abs(xdf-mousedf).gt.DFTolerance) goto 10
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idiff=abs(ipk(nbest)-ipk(n2best))
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xk=float(idiff)/nfac
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k=nint(xk)
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iderr=nint((xk-k)*nfac)
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nspecial=0
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maxerr=nint(0.008*abs(idiff) + 0.51)
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if(abs(iderr).le.maxerr .and. k.ge.2 .and. k.le.4) nspecial=k
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if(nspecial.gt.0) then
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call getsnr(ss(ia2,nbest),ib2-ia2+1,snr1)
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call getsnr(ss(ia2,n2best),ib2-ia2+1,snr2)
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snr=0.5*(snr1+snr2)
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if(snr.gt.snrbest) then
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snrbest=snr
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nspecialbest=nspecial
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nstest=snr/2.0 - 2.0 !Threshold set here
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if(nstest.lt.0) nstest=0
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if(nstest.gt.10) nstest=10
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dfsh=nint(xdf)
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fdotbest=fdotsh
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iderrbest=iderr
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idiffbest=idiff
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idriftbest=idrift
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snrdb=db(snr) - db(2500.0/df) - db(sqrt(nsteps/4.0))+1.8
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n1=nbest
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n2=n2best
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ipk1=ipk(n1)
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ipk2=ipk(n2)
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endif
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endif
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if(nstest.eq.0) nspecial=0
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10 enddo
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if(nstest.eq.0) nspecialbest=0
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if(nstest.gt.0) then
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df4=4.0*df
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if(ipk1.gt.ipk2) then
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ntmp=n1
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n1=n2
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n2=ntmp
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ntmp=ipk1
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ipk1=ipk2
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ipk2=ntmp
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endif
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call zero(ss1,449)
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call zero(ss2,449)
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do i=ia2,ib2,4
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f=df*i
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k=nint((f-1270.46)/df4)
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if(k.ge.-224 .and. k.le.224) then
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ss1(k)=0.3 * (ss(i-2,n1) + ss(i-1,n1) + ss(i,n1) +
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+ ss(i+1,n1) + ss(i+2,n1))
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ss2(k)=0.3 * (ss(i-2,n2) + ss(i-1,n2) + ss(i,n2) +
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+ ss(i+1,n2) + ss(i+2,n2))
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endif
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enddo
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! kpk1=nint(0.25*ipk(n1)-472.0)
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kpk1=nint(0.25*ipk1-472.0)
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kpk2=kpk1 + nspecial*mode65*10
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ssmax=0.
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do i=-10,10
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ssavg(i)=ss1(kpk1+i) + ss2(kpk2+i)
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if(ssavg(i).gt.ssmax) then
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ssmax=ssavg(i)
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itop=i
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endif
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enddo
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base=0.25*(ssavg(-10)+ssavg(-9)+ssavg(9)+ssavg(10))
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shalf=0.5*(ssmax+base)
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do k=1,8
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if(ssavg(itop-k).lt.shalf) go to 110
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enddo
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k=8
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110 x=(ssavg(itop-(k-1))-shalf)/(ssavg(itop-(k-1))-ssavg(itop-k))
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do k=1,8
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if(ssavg(itop+k).lt.shalf) go to 120
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enddo
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k=8
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120 x=x+(ssavg(itop+(k-1))-shalf)/(ssavg(itop+(k-1))-ssavg(itop+k))
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nwsh=nint(x*df4)
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endif
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return
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end
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