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https://github.com/saitohirga/WSJT-X.git
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97 lines
2.2 KiB
Fortran
97 lines
2.2 KiB
Fortran
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subroutine specjtms(k)
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! Starting code for a JTMS3 decoder.
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parameter (NSMAX=30*48000)
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parameter (NFFT=8192,NH=NFFT/2)
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integer*2 id
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real x(NFFT),w(NFFT)
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complex cx(NFFT),cx2(NFFT)
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complex covx(NH)
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real s1a(NH),s2a(580)
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logical first,window
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common/mscom/id(1440000),s1(215,703),s2(215,703)
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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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do i=1,nfft
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w(i)=(sin(i*pi/nfft))**2
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enddo
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df=48000.0/nfft
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ja=nint(2600.0)/df
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jb=nint(3400.0)/df
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iz=3000.0/df
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covx=0.
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window=.false.
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first=.false.
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endif
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ib=k
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ia=k-4095
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i0=ib-8191
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sq=0.
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do i=ia,ib
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sq=sq + (0.001*id(i))**2
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enddo
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write(13,1010) t,sq,db(sq)
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1010 format(3f12.3)
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if(k.lt.8192) return
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x(1:nfft)=0.001*id(i0:ib)
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! call analytic(x,nfft,nfft,s,cx)
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fac=2.0/nfft
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cx=fac*x
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if(window) cx=w*cx
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call four2a(cx,nfft,1,-1,1) !Forward c2c FFT
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do i=1,iz !Save spectrum for plot
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s1a(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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if(window) then
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cx(1:nh)=cx(1:nh)+covx(1:nh) !Add previous segment's 2nd half
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covx(1:nh)=cx(nh+1:nfft) !Save 2nd half
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endif
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t=k/48000.0
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cx2=cx*cx
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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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do j=ja,jb
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sq=1.e-6*(real(cx2(j))**2 + aimag(cx2(j))**2)
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s2a(j)=sq
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f=(j-1)*df
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if(sq.gt.spk0) then
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spk0=sq
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f0=0.5*(f-3000.0)
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phi0=atan2(aimag(cx2(j)),real(cx2(j)))
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endif
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write(15,1020) (j-1)*df,sq
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1020 format(f10.3,f12.3)
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enddo
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slimit=1.5
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if(spk0.gt.slimit) then
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write(*,1030) t,f0,phi0,spk0
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1030 format('t:',f6.2,' f0:',f7.1,' phi0:',f6.2,' spk0:',f8.1)
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do i=1,iz
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write(16,1040) i*df,s1a(i),db(s1a(i))
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1040 format(3f12.3)
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enddo
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do j=ja,jb
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f=(j-1)*df
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f0a=0.5*(f-3000.0)
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write(17,1050) f0a,s2a(j)
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1050 format(2f12.3)
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enddo
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endif
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end subroutine specjtms
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