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https://github.com/saitohirga/WSJT-X.git
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a93e55fef0
procedure; better window functions for some FFTs, resulting in better decoder performance; User-selectable colors for backgrounds of decoded messages. NB: more testing is desirable! git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@4951 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
61 lines
1.4 KiB
Fortran
61 lines
1.4 KiB
Fortran
subroutine symspec65(dd,npts,ss,nhsym,savg)
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! Compute JT65 symbol spectra at half-symbol steps
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parameter (NFFT=8192)
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parameter (NSZ=3413) !NFFT*5000/12000
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parameter (MAXHSYM=322)
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real*8 hstep
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real*4 dd(npts)
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real*4 ss(MAXHSYM,NSZ)
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real*4 savg(NSZ)
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real*4 x(NFFT)
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real*4 w(NFFT)
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complex c(0:NFFT/2)
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logical first
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common/refspec/dfref,ref(NSZ)
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equivalence (x,c)
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data first/.true./
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save /refspec/,first,w
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hstep=2048.d0*12000.d0/11025.d0 !half-symbol = 2229.116 samples
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nsps=nint(2*hstep)
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df=12000.0/NFFT
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nhsym=(npts-NFFT)/hstep
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savg=0.
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fac1=1.e-3
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if(first) then
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! Compute the FFT window
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pi=4.0*atan(1.0)
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width=0.25*nsps
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do i=1,NFFT
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z=(i-NFFT/2)/width
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w(i)=exp(-z*z)
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enddo
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first=.false.
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endif
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do j=1,nhsym
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i0=(j-1)*hstep
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x=fac1*w*dd(i0+1:i0+NFFT)
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call four2a(c,NFFT,1,-1,0) !r2c forward FFT
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do i=1,NSZ
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s=real(c(i))**2 + aimag(c(i))**2
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ss(j,i)=s
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savg(i)=savg(i)+s
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enddo
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enddo
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savg=savg/nhsym
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call flat65(ss,nhsym,MAXHSYM,NSZ,ref) !Flatten the 2d spectrum, saving
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dfref=df ! the reference spectrum ref()
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savg=savg/ref
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do j=1,nhsym
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ss(j,1:NSZ)=ss(j,1:NSZ)/ref
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enddo
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return
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end subroutine symspec65
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