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More work on msk144 decoder.
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@6791 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
This commit is contained in:
Steven Franke
parent
c1348777ea
commit
8b011a83e6
@ -13,7 +13,7 @@ subroutine analytic(d,npts,nfft,c)
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nh=nfft/2
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if(nfft.ne.nfft0) then
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t=1.0/2000.0
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beta=0.6
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beta=0.1
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pi=4.0*atan(1.0)
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do i=1,nh+1
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ff=(i-1)*df
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@ -23,7 +23,7 @@ subroutine analytic(d,npts,nfft,c)
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if(abs(f).gt.(1-beta)/(2*t) .and. abs(f).le.(1+beta)/(2*t)) then
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h(i)=0.5*(1+cos((pi*t/beta )*(abs(f)-(1-beta)/(2*t))))
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endif
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h(i)=sqrt(h(i))
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! h(i)=sqrt(h(i))
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enddo
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nfft0=nfft
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endif
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@ -1,7 +1,7 @@
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subroutine detectmsk144(cbig,n,pchk_file,lines,nmessages,nutc)
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use timer_module, only: timer
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parameter (NSPM=864, NPTS=3*NSPM, MAXSTEPS=1500)
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parameter (NSPM=864, NPTS=3*NSPM, MAXSTEPS=1700, NFFT=NSPM)
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character*22 msgreceived,allmessages(20)
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character*80 lines(100)
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character*512 pchk_file,gen_file
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@ -9,7 +9,7 @@ subroutine detectmsk144(cbig,n,pchk_file,lines,nmessages,nutc)
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complex cdat(NPTS) !Analytic signal
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complex cdat2(NPTS)
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complex c(NSPM)
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complex ctmp(6000)
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complex ctmp(NFFT)
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complex cb(42) !Complex waveform for sync word
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complex cfac,cca,ccb
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complex cc(NPTS)
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@ -21,17 +21,18 @@ subroutine detectmsk144(cbig,n,pchk_file,lines,nmessages,nutc)
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integer*1 decoded(80)
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integer indices(MAXSTEPS)
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integer ipeaks(10)
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logical ismask(6000)
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logical ismask(NFFT)
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real cbi(42),cbq(42)
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real detmet(-2:MAXSTEPS+3)
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real detfer(MAXSTEPS)
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real tonespec(6000)
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real hannwindow(NPTS)
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real rcw(12)
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real dd(NPTS)
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real ferrs(20)
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real pp(12) !Half-sine pulse shape
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real snrs(20)
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real times(20)
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real tonespec(NFFT)
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real*8 dt, df, fs, pi, twopi
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real softbits(144)
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real*8 unscrambledsoftbits(128)
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@ -39,7 +40,7 @@ subroutine detectmsk144(cbig,n,pchk_file,lines,nmessages,nutc)
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logical first
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data first/.true./
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data s8/0,1,1,1,0,0,1,0/
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save df,first,cb,fs,nfft,pi,twopi,dt,s8,rcw,pp
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save df,first,cb,fs,pi,twopi,dt,s8,rcw,pp,hannwindow
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if(first) then
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nmatchedfilter=1
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@ -51,8 +52,7 @@ subroutine detectmsk144(cbig,n,pchk_file,lines,nmessages,nutc)
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twopi=8d0*datan(1d0)
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fs=12000.0
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dt=1.0/fs
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nfft=6000 !using a zero-padded fft to get 2 Hz bins
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df=fs/nfft
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df=fs/NFFT
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do i=1,12
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angle=(i-1)*pi/12.0
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@ -60,6 +60,10 @@ subroutine detectmsk144(cbig,n,pchk_file,lines,nmessages,nutc)
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rcw(i)=(1-cos(angle))/2
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enddo
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do i=1,NPTS
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hannwindow(i)=0.5*(1-cos(twopi*(i-1)/NPTS))
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enddo
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! define the sync word waveform
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s8=2*s8-1
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cbq(1:6)=pp(7:12)*s8(1)
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@ -76,66 +80,87 @@ subroutine detectmsk144(cbig,n,pchk_file,lines,nmessages,nutc)
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endif
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! fill the detmet, detferr arrays
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nstep=(n-NSPM)/256
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nstep=(n-NPTS)/216 ! 72ms/4=18ms steps
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detmet=0
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detmax=-999.99
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detfer=-999.99
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do istp=1,nstep
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ns=1+256*(istp-1)
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ne=ns+NPTS-1
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ns=1+216*(istp-1)
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ne=ns+NSPM-1
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if( ne .gt. n ) exit
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cdat=cbig(ns:ne)
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ctmp=cmplx(0.0,0.0)
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ctmp(1:NSPM)=cbig(ns:ne)
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! Coarse carrier frequency sync - seek tones at 2000 Hz and 4000 Hz in
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! squared signal spectrum.
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! search range for coarse frequency error is +/- 100 Hz
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ctmp=cmplx(0.0,0.0)
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ctmp(1:NPTS)=cdat**2
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ctmp=ctmp**2
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ctmp(1:12)=ctmp(1:12)*rcw
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ctmp(NPTS-11:NPTS)=ctmp(NPTS-11:NPTS)*rcw(12:1:-1)
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call four2a(ctmp,nfft,1,-1,1)
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ctmp(NSPM-11:NSPM)=ctmp(NSPM-11:NSPM)*rcw(12:1:-1)
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! ctmp(1:NSPM)=ctmp(1:NSPM)*hannwindow
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call four2a(ctmp,NFFT,1,-1,1)
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tonespec=abs(ctmp)**2
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i3800=3800/df+1
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i4200=4200/df+1
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ismask=.false.
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ismask(1901:2101)=.true. ! high tone search window
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ismask(i3800:i4200)=.true. ! high tone search window
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iloc=maxloc(tonespec,ismask)
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ihpk=iloc(1)
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deltah=-real( (ctmp(ihpk-1)-ctmp(ihpk+1)) / (2*ctmp(ihpk)-ctmp(ihpk-1)-ctmp(ihpk+1)) )
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ah=tonespec(ihpk)
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i1800=1800/df+1
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i2200=2200/df+1
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ismask=.false.
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ismask(901:1101)=.true. ! window for low tone
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ismask(i1800:i2200)=.true. ! window for low tone
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iloc=maxloc(tonespec,ismask)
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ilpk=iloc(1)
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deltal=-real( (ctmp(ilpk-1)-ctmp(ilpk+1)) / (2*ctmp(ilpk)-ctmp(ilpk-1)-ctmp(ilpk+1)) )
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al=tonespec(ilpk)
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fdiff=(ihpk-ilpk)*df
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ferrh=(ihpk-2001)*df/2.0
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ferrl=(ilpk-1001)*df/2.0
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if( abs(fdiff-2000) .le. 16.0 ) then
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fdiff=(ihpk+deltah-ilpk-deltal)*df
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i2000=2000/df+1
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i4000=4000/df+1
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ferrh=(ihpk+deltah-i4000)*df/2.0
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ferrl=(ilpk+deltal-i2000)*df/2.0
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! if( abs(fdiff-2000) .le. 25.0 ) then
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if( ah .ge. al ) then
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ferr=ferrh
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else
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ferr=ferrl
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endif
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else
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ferr=-999.99
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endif
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detmet(istp)=ah+al
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! else
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! ferr=-999.99
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! endif
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! detmet(istp)=ah+al
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detmet(istp)=max(ah,al)
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detfer(istp)=ferr
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! if( detmet(istp) .gt. detmax ) then
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! open(unit=77,file="tonespec.dat")
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! do i=1,NFFT
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! write(77,*) (i-1)*df,tonespec(i)
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! enddo
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! close(77)
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! detmax=detmet(istp)
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! endif
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!write(*,*) ihpk,ilpk,deltah,deltal,ferrh,ferrl,fdiff
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enddo ! end of detection-metric and frequency error estimation loop
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call indexx(detmet(1:nstep),nstep,indices) !find median of detection metric vector
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xmed=detmet(indices(nstep/2))
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detmet=detmet/xmed ! noise floor of detection metric is 1.0
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ndet=0
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do ip=1,20 ! use something like the "clean" algorithm to find candidates
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iloc=maxloc(detmet(1:nstep))
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il=iloc(1)
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if( (detmet(il) .lt. 1.5) .or. (abs(detfer(il)) .gt. 100.0) ) cycle
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if( (detmet(il) .lt. 2.0) .or. (abs(detfer(il)) .gt. 100.0) ) cycle
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ndet=ndet+1
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times(ndet)=((il-1)*256+NPTS/2)*dt
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times(ndet)=((il-1)*216+NSPM/2)*dt
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ferrs(ndet)=detfer(il)
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snrs(ndet)=10.0*log10(detmet(il))/2-5.0 !/2 because detmet is a 4th order moment
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detmet(il-3:il+3)=0.0
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! write(*,*) ndet,"snr ",snrs(ndet),"ferr ",ferrs(ndet)
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enddo
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nmessages=0
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@ -182,14 +207,15 @@ subroutine detectmsk144(cbig,n,pchk_file,lines,nmessages,nutc)
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! fine adjustment of sync index
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do i=1,6
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if( ic0+11+NSPM .le. NPTS ) then
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bb(i) = sum( ( cdat(ic0+i-1+6:ic0+i-1+6+NSPM:6) * conjg( cdat(ic0+i-1:ic0+i-1+NSPM:6) ) )*2 )
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bb(i) = sum( ( cdat(ic0+i-1+6:ic0+i-1+6+NSPM:6) * conjg( cdat(ic0+i-1:ic0+i-1+NSPM:6) ) )**2 )
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else
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bb(i) = sum( ( cdat(ic0+i-1+6:NPTS:6) * conjg( cdat(ic0+i-1:NPTS-6:6) ) )*2 )
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bb(i) = sum( ( cdat(ic0+i-1+6:NPTS:6) * conjg( cdat(ic0+i-1:NPTS-6:6) ) )**2 )
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endif
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enddo
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iloc=maxloc(abs(bb))
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ibb=iloc(1)
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bba=abs(bb(ibb))
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bbp=atan2(-imag(bb(ibb)),-real(bb(ibb)))/(2*twopi*6*dt)
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if( ibb .le. 3 ) ibb=ibb-1
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if( ibb .gt. 3 ) ibb=ibb-7
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@ -260,7 +286,7 @@ subroutine detectmsk144(cbig,n,pchk_file,lines,nmessages,nutc)
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cfac=ccb*conjg(cca)
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ffin=atan2(imag(cfac),real(cfac))/(twopi*56*6*dt)
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phase0=atan2(imag(cca+ccb),real(cca+ccb))
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! Remove phase error - want constellation rotated so that sample points lie on I/Q axes
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cfac=cmplx(cos(phase0),sin(phase0))
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c=c*conjg(cfac)
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@ -293,7 +319,7 @@ subroutine detectmsk144(cbig,n,pchk_file,lines,nmessages,nutc)
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nbadsync1=(8-sum( (2*hardbits(1:8)-1)*s8 ) )/2
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nbadsync2=(8-sum( (2*hardbits(1+56:8+56)-1)*s8 ) )/2
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nbadsync=nbadsync1+nbadsync2
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if( nbadsync .gt. 6 ) cycle
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if( nbadsync .gt. 4 ) cycle
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! normalize the softsymbols before submitting to decoder
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sav=sum(softbits)/144
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@ -331,7 +357,7 @@ subroutine detectmsk144(cbig,n,pchk_file,lines,nmessages,nutc)
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else
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msgreceived=' '
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ndither=-99 ! -99 is bad hash flag
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! write(78,1001) nutc,t0,nsnr,ipk,is,idf,iav,deltaf,fest,ffin,nbadsync1,nbadsync2, &
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! write(78,1001) nutc,t0,nsnr,ipk,is,idf,iav,deltaf,fest,ferr,ferr2,ffin,bba,bbp,nbadsync1,nbadsync2, &
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! phase0,niterations,ndither,msgreceived
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endif
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endif
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@ -343,9 +369,13 @@ subroutine detectmsk144(cbig,n,pchk_file,lines,nmessages,nutc)
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msgreceived=' '
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ndither=-98
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999 continue
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! write(78,1001) nutc,t0,nsnr,ipk,is,idf,iav,deltaf,fest,ffin,nbadsync1,nbadsync2, &
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if( nmessages .ge. 1 ) then
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! write(78,1001) nutc,t0,nsnr,ipk,is,idf,iav,deltaf,fest,ferr,ferr2,ffin,bba,bbp,nbadsync1,nbadsync2, &
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! phase0,niterations,ndither,msgreceived
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!1001 format(i6.6,f8.2,i4,i4,i4,i4,i4,f8.2,f8.2,f8.2,i4,i4,f8.2,i5,i5,2x,a22)
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! call flush(78)
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!1001 format(i6.6,f8.2,i4,i4,i4,i4,i4,f8.2,f8.2,f8.2,f8.2,f8.2,f8.2,f8.2,i4,i4,f8.2,i5,i5,2x,a22)
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exit
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endif
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enddo
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return
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end subroutine detectmsk144
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@ -67,6 +67,7 @@ program msk144sim
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call makepings(pings,NMAX,width,sig)
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! call sgran()
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do ifile=1,nfiles !Loop over requested number of files
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write(fname,1002) ifile !Output filename
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1002 format('000000_',i6.6)
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