mirror of https://github.com/saitohirga/WSJT-X.git
159 lines
4.1 KiB
Fortran
159 lines
4.1 KiB
Fortran
subroutine refspectrum(id2,bclear,brefspec,buseref,fname)
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! Input:
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! id2 i*2 Raw 16-bit integer data, 12000 Hz sample rate
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! brefspec logical True when accumulating a reference spectrum
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parameter (NFFT=6912,NH=NFFT/2,NPOLYLOW=400,NPOLYHIGH=2600)
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integer*2 id2(NFFT)
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logical*1 bclear,brefspec,buseref,blastuse
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real xs(0:NH-1) !Saved upper half of input chunk convolved with h(t)
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real x(0:NFFT-1) !Work array
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real*4 w(0:NFFT-1) !Window function
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real*4 s(0:NH) !Average spectrum
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real*4 fil(0:NH)
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real*8 xfit(1500),yfit(1500),sigmay(1500),a(5),chisqr !Polyfit arrays
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logical first
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complex cx(0:NH) !Complex frequency-domain work array
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complex cfil(0:NH)
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character*(*) fname
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common/spectra/syellow(6827),ref(0:NH),filter(0:NH)
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equivalence(x,cx)
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data first/.true./,blastuse/.false./
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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=0,NFFT-1
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ww=sin(i*pi/NFFT)
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w(i)=ww*ww/NFFT
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enddo
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nsave=0
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s=0.0
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filter=1.0
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xs=0.
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first=.false.
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endif
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if(bclear) s=0.
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if(brefspec) then
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x(0:NH-1)=0.001*id2(1:NH)
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x(NH:NFFT-1)=0.0
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call four2a(cx,NFFT,1,-1,0) !r2c FFT
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do i=1,NH
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s(i)=s(i) + real(cx(i))**2 + aimag(cx(i))**2
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enddo
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nsave=nsave+1
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fac0=0.9
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if(mod(nsave,4).eq.0) then
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df=12000.0/NFFT
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ia=nint(1000.0/df)
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ib=nint(2000.0/df)
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avemid=sum(s(ia:ib))/(ib-ia+1)
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do i=0,NH
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fil(i)=0.
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if(s(i).gt.0.0) then
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fil(i)=sqrt(avemid/s(i))
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endif
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enddo
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! Default range is 240 - 4000 Hz. For narrower filters, use frequencies
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! at which gain is -20 dB relative to 1500 Hz.
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ia=nint(240.0/df)
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ib=nint(4000.0/df)
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i0=nint(1500.0/df)
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do i=i0,ia,-1
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if(s(i)/s(i0).lt.0.01) exit
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enddo
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ia=i
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do i=i0,ib,1
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if(s(i)/s(i0).lt.0.01) exit
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enddo
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ib=i
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fac=fac0
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do i=ia,1,-1
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fac=fac*fac0
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fil(i)=fac*fil(i)
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enddo
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fac=fac0
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do i=ib,NH
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fac=fac*fac0
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fil(i)=fac*fil(i)
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enddo
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do iter=1,100 !### ??? ###
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call smo121(fil,NH)
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enddo
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do i=0,NH
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filter(i)=-60.0
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if(s(i).gt.0.0) filter(i)=20.0*log10(fil(i))
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enddo
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il=nint(NPOLYLOW/df)
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ih=nint(NPOLYHIGH/df)
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nfit=ih-il+1
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mode=0
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nterms=5
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do i=1,nfit
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xfit(i)=((i+il-1)*df-1500.0)/1000.0
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yfit(i)=fil(i+il-1)
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sigmay(i)=1.0
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enddo
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call polyfit(xfit,yfit,sigmay,nfit,nterms,mode,a,chisqr)
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open(16,file=fname,status='unknown')
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write(16,1003) NPOLYLOW,NPOLYHIGH,nterms,a
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1003 format(3i5,5e25.16)
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do i=1,NH
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freq=i*df
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ref(i)=db(s(i)/avemid)
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write(16,1005) freq,s(i),ref(i),fil(i),filter(i)
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1005 format(f10.3,e12.3,f12.6,e12.3,f12.6)
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enddo
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close(16)
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endif
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return
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endif
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if(buseref) then
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if(blastuse.neqv.buseref) then !just enabled so read filter
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fil=1.0
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open(16,file=fname,status='old',err=999)
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read(16,1003,err=20,end=999) ndummy,ndummy,nterms,a
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goto 30
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20 rewind(16) !allow for old style refspec.dat with no header
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30 do i=1,NH
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read(16,1005,err=999,end=999) freq,s(i),ref(i),fil(i),filter(i)
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enddo
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! Make the filter causal for overlap and add.
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cx(0)=0.0
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cx(1:NH)=fil(1:NH)/NFFT
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call four2a(cx,NFFT,1,1,-1)
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x=cshift(x,-400)
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x(800:NH)=0.0
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call four2a(cx,NFFT,1,-1,0)
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cfil=cx
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close(16)
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endif
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! Use overlap and add method to apply causal reference filter.
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x(0:NH-1)=id2(1:NH)
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x(NH:NFFT-1)=0.0
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x=x/NFFT
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call four2a(cx,NFFT,1,-1,0)
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cx=cfil*cx
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call four2a(cx,NFFT,1,1,-1)
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x(0:NH-1)=x(0:NH-1)+xs
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xs=x(NH:NFFT-1)
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id2(1:NH)=nint(x(0:NH-1))
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endif
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blastuse=buseref
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999 return
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end subroutine refspectrum
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