mirror of
https://github.com/saitohirga/WSJT-X.git
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125 lines
2.6 KiB
FortranFixed
125 lines
2.6 KiB
FortranFixed
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subroutine spec2d(data,jz,nstep,s2,nchan,nz,psavg0,sigma)
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C Computes 2d spectrogram for FSK441 single-tone search and waterfall
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C display.
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parameter (NFFT=256)
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parameter (NR=NFFT+2)
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parameter (NH=NFFT/2)
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parameter (NQ=NFFT/4)
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real data(jz)
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real s2(nchan,nz)
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real x(NR)
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real w1(7),w2(7)
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real psavg(128)
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real psavg0(128)
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real ps2(128)
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complex c(0:NH)
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common/acom/a1,a2,a3,a4
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common/fcom/s(3100),indx(3100)
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equivalence (x,c)
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save
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df=11025.0/NFFT
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C Compute the 2d spectrogram s2(nchan,nz). Note that in s2 the frequency
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C bins are shifted down 5 bins from their natural positions.
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call set(0.0,psavg,NH)
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do n=1,nz
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j=1 + (n-1)*nstep
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call move(data(j),x,NFFT)
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call xfft(x,NFFT)
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sum=0.
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do i=1,NQ
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s2(i,n)=real(c(5+i))**2 + imag(c(5+i))**2
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sum=sum+s2(i,n)
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enddo
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s(n)=sum/NQ
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C Accumulate average spectrum for the whole file.
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do i=1,nh
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psavg0(i) = psavg0(i)+ real(c(i))**2 + imag(c(i))**2
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enddo
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enddo
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C Normalize and save a copy of psavg0 for plotting. Roll off the
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C spectrum at 300 and 3000 Hz.
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do i=1,nh
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psavg0(i)=3.e-5*psavg0(i)/nz
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f=df*i
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fac=1.0
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if(f.lt.300.0) fac=f/300.0
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if(f.gt.3000.0) fac=max(0.00333,(3300.0-f)/300.0)
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psavg0(i)=(fac**2)*psavg0(i)
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enddo
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C Compute an average spectrum from the weakest 25% of time slices.
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call indexx(nz,s,indx)
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call zero(ps2,NQ)
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do j=1,nz/4
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k=indx(j)
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do i=1,NQ
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ps2(i+5)=ps2(i+5)+s2(i,k)
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enddo
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enddo
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ps2(1)=ps2(5)
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ps2(2)=ps2(5)
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ps2(3)=ps2(5)
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ps2(4)=ps2(5)
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sum=0.
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do i=6,59
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sum=sum+ps2(i)
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enddo
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C Compute a smoothed spectrum without local peaks, and find its max.
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smaxx=0.
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do i=4,NQ
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sum=0.
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do k=1,7
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w1(k)=ps2(i+k-4)
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sum=sum+w1(k)
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enddo
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ave=sum/7.0
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if(i.ge.14 .and. i.le.58) then
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call pctile(w1,w2,7,50,base)
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ave=0.25*(w2(1)+w2(2)+w2(3)+w2(4))
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endif
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psavg(i)=ave
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smaxx=max(psavg(i),smaxx)
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enddo
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C Save scale factors for flattening spectra of pings.
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a1=1.0
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a2=psavg(nint(2*441/df))/psavg(nint(3*441/df))
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a3=psavg(nint(2*441/df))/psavg(nint(4*441/df))
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a4=psavg(nint(2*441/df))/psavg(nint(5*441/df))
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afac=4.0/(a1+a2+a3+a4)
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a1=afac*a1
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a2=afac*a2
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a3=afac*a3
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a4=afac*a4
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C Normalize 2D spectrum by the average based on weakest 25% of time
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C slices, smoothed, and with local peaks removed.
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do i=1,NQ
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do j=1,nz
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s2(i,j)=s2(i,j)/max(psavg(i+5),0.01*smaxx)
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enddo
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enddo
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C Find average of active spectral region, over the whole file.
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sum=0.
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do i=9,52
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do j=1,nz
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sum=sum+s2(i,j)
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enddo
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enddo
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sigma=sum/(44*nz)
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return
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end
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