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https://github.com/saitohirga/WSJT-X.git
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d91aed5aee
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
124 lines
3.2 KiB
Fortran
124 lines
3.2 KiB
Fortran
subroutine symspec(k,ntrperiod,nsps,ingain,nflatten,pxdb,s,df3,ihsym,npts8)
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! Input:
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! k pointer to the most recent new data
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! ntrperiod T/R sequence length, minutes
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! nsps samples per symbol, at 12000 Hz
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! ndiskdat 0/1 to indicate if data from disk
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! nb 0/1 status of noise blanker (off/on)
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! nbslider NB setting, 0-100
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! Output:
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! pxdb power (0-60 dB)
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! s() current spectrum for waterfall display
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! ihsym index number of this half-symbol (1-184)
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! jt9com
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! ss() JT9 symbol spectra at half-symbol steps
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! savg() average spectra for waterfall display
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include 'constants.f90'
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real*4 w3(MAXFFT3)
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real*4 s(NSMAX)
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real*4 ssum(NSMAX)
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real*4 xc(0:MAXFFT3-1)
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real*4 tmp(NSMAX)
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complex cx(0:MAXFFT3/2)
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integer*2 id2
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common/jt9com/ss(184,NSMAX),savg(NSMAX),id2(NMAX),nutc,ndiskdat, &
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ntr,mousefqso,newdat,npts8a,nfa,nfsplit,nfb,ntol,kin,nzhsym, &
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nsave,nagain,ndepth,ntxmode,nmode,junk(5)
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common/jt9w/syellow(NSMAX)
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data rms/999.0/,k0/99999999/,nfft3z/0/
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equivalence (xc,cx)
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save
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if(ntrperiod.eq.-999) stop !Silence compiler warning
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nfft3=16384 !df=12000.0/16384 = 0.732422
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jstep=nsps/2 !Step size = half-symbol in id2()
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if(k.gt.NMAX) go to 900
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if(k.lt.2048) then !(2048 was nfft3) (Any need for this ???)
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ihsym=0
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go to 900 !Wait for enough samples to start
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endif
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if(nfft3.ne.nfft3z) then
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! Compute new 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,nfft3
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z=(i-nfft3/2)/width
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w3(i)=exp(-z*z)
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enddo
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nfft3z=nfft3
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endif
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if(k.lt.k0) then !Start a new data block
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ja=0
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ssum=0.
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ihsym=0
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if(ndiskdat.eq.0) id2(k+1:)=0 !Needed to prevent "ghosts". Not sure why.
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endif
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gain=10.0**(0.1*ingain)
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sq=0.
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do i=k0+1,k
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x1=id2(i)
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sq=sq + x1*x1
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enddo
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sq=sq * gain
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rms=sqrt(sq/(k-k0))
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pxdb=0.
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if(rms.gt.0.0) pxdb=20.0*log10(rms)
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if(pxdb.gt.60.0) pxdb=60.0
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k0=k
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ja=ja+jstep !Index of first sample
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fac0=0.1
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do i=0,nfft3-1 !Copy data into cx
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j=ja+i-(nfft3-1)
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xc(i)=0.
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if(j.ge.1) xc(i)=fac0*id2(j)
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enddo
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if(ihsym.lt.184) ihsym=ihsym+1
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xc(0:nfft3-1)=w3(1:nfft3)*xc(0:nfft3-1) !Apply window w3
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call four2a(xc,nfft3,1,-1,0) !Real-to-complex FFT
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n=min(184,ihsym)
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df3=12000.0/nfft3 !JT9-1: 0.732 Hz = 0.42 * tone spacing
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! i0=nint(1000.0/df3)
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i0=0
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iz=min(NSMAX,nint(5000.0/df3))
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fac=(1.0/nfft3)**2
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do i=1,iz
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j=i0+i-1
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if(j.lt.0) j=j+nfft3
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sx=fac*(real(cx(j))**2 + aimag(cx(j))**2)
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ss(n,i)=sx
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ssum(i)=ssum(i) + sx
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s(i)=1000.0*gain*sx
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enddo
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savg=ssum/ihsym
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if(mod(n,10).eq.0) then
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mode4=36
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nsmo=min(10*mode4,150)
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nsmo=4*nsmo
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call flat1(savg,iz,nsmo,syellow)
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if(mode4.ge.9) call smo(syellow,iz,tmp,mode4)
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ia=500./df3
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ib=2700.0/df3
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smin=minval(syellow(ia:ib))
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smax=maxval(syellow(1:iz))
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syellow=(50.0/(smax-smin))*(syellow-smin)
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where(syellow<0) syellow=0.
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endif
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900 npts8=k/8
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return
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end subroutine symspec
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