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ec33088d69
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/jtms3@2508 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
89 lines
1.8 KiB
Fortran
89 lines
1.8 KiB
Fortran
subroutine specjtms(k,px,pxsmo,spk0,f0)
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! Starting code for a JTMS3 decoder.
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parameter (NSMAX=30*48000)
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parameter (MAXFFT=8192)
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integer*2 id
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real x(MAXFFT)
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complex cx(MAXFFT),cx2(MAXFFT)
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logical first
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common/mscom/id(1440000),s1(215),s2(215)
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data first/.true./
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save
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if(first) then
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pi=4.0*atan(1.0)
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twopi=2.0*pi
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kstep=2048
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first=.false.
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sqsmo=0.
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endif
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t=k/48000.0
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nfft=4096
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df=48000.0/nfft
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nh=nfft/2
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ib=k
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ia=k-kstep+1
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i0=k-nfft+1
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sq=0.
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do i=ia,ib
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d=id(i)
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sq=sq + d*d
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enddo
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sq=sq/2048.0
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sqsmo=0.95*sqsmo + 0.05*sq
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rms=sqrt(sq)
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px=db(sq) - 23.0
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pxsmo=db(sqsmo) - 23.0
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! write(13,1010) t,rms,sq,px,pxsmo
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!1010 format(5f12.3)
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if(k.lt.nfft) return
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x(1:nfft)=id(i0:ib)
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fac=0.002/nfft
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cx=fac*x
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call four2a(cx,nfft,1,-1,1) !Forward c2c FFT
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iz=nint(2500.0/df)
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do i=1,iz !Save spectrum for plot
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s1(i)=real(cx(i+1))**2 + aimag(cx(i+1))**2
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enddo
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cx(1)=0.5*cx(1)
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cx(nh+2:nfft)=0.
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call four2a(cx,nfft,1,1,1) !Inverse c2c FFT
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cx2(1:nfft)=cx(1:nfft)*cx(1:nfft)
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cx2(nfft+1:)=0.0
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nfft=8192
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df=48000.0/nfft
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call four2a(cx2,nfft,1,-1,1) !Forward c2c FFT of cx2
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spk0=0.
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j0=nint(2.0*1428.57/df)
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ja=j0-107
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jb=j0+107
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do j=ja,jb
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sq=1.e-4*(real(cx2(j))**2 + aimag(cx2(j))**2)
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s2(j-ja+1)=sq
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if(sq.gt.spk0) then
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spk0=sq
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f=(j-1)*df
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f0=0.5*(f-3000.0)
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phi0=0.5*atan2(aimag(cx2(j)),real(cx2(j)))
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endif
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enddo
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spk0=0.5*db(spk0) - 7.0
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! write(14,3001) k/2048,spk0,f0,phi0
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!3001 format(i8,3f12.3)
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call flush(14)
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return
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end subroutine specjtms
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