mirror of https://github.com/saitohirga/WSJT-X.git
463 lines
14 KiB
Fortran
463 lines
14 KiB
Fortran
subroutine detectmsk32(cbig,n,mycall,partnercall,lines,nmessages,nutc)
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use timer_module, only: timer
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parameter (NSPM=192, NPTS=3*NSPM, MAXSTEPS=7500, NFFT=3*NSPM, MAXCAND=40)
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character*4 rpt(0:31)
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character*6 mycall,partnercall
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character*22 msg,hashmsg,msgreceived,allmessages(20)
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character*80 lines(100)
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complex cbig(n)
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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(NFFT)
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complex cb(42) !Complex waveform for sync word
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complex cbr(42) !Complex waveform for reversed sync word
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complex cfac,cca,ccb
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complex cc(NPTS)
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complex ccr(NPTS)
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complex cc1(NPTS)
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complex cc2(NPTS)
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complex ccr1(NPTS)
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complex ccr2(NPTS)
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complex bb(6)
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integer s8(8),s8r(8),hardbits(32)
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integer, dimension(1) :: iloc
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integer ihammd(0:4096-1)
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integer indices(MAXSTEPS)
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integer ipeaks(10)
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integer ig24(0:4096-1)
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integer likelymessages(0:31)
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logical qsocontext
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logical ismask(NFFT)
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real cbi(42),cbq(42)
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real cd(0:4095)
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real detmet(-2:MAXSTEPS+3)
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real detfer(MAXSTEPS)
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real rcw(12)
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real dd(NPTS)
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real ddr(NPTS)
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real ferrs(MAXCAND)
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real pp(12) !Half-sine pulse shape
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real snrs(MAXCAND)
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real times(MAXCAND)
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real tonespec(NFFT)
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real*8 dt, df, fs, pi, twopi
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real softbits(32)
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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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data s8r/1,0,1,1,0,0,0,1/
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data rpt /'-04 ','-03 ','-02 ','-01 ','00 ','01 ','02 ','03 ','04 ', &
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'05 ','06 ','07 ','08 ','09 ','10 ', &
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'R-04','R-03','R-02','R-01','R00','R01','R02','R03','R04', &
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'R05','R06','R07','R08','R09','R10', &
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'RRR ','73 '/
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save df,first,cb,cbr,fs,pi,twopi,dt,s8,rcw,pp,nmatchedfilter,ig24
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if(first) then
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nmatchedfilter=1
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! define half-sine pulse and raised-cosine edge window
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pi=4d0*datan(1d0)
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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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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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pp(i)=sin(angle)
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rcw(i)=(1-cos(angle))/2
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enddo
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! define the sync word waveforms
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s8=2*s8-1
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cbq(1:6)=pp(7:12)*s8(1)
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cbq(7:18)=pp*s8(3)
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cbq(19:30)=pp*s8(5)
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cbq(31:42)=pp*s8(7)
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cbi(1:12)=pp*s8(2)
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cbi(13:24)=pp*s8(4)
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cbi(25:36)=pp*s8(6)
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cbi(37:42)=pp(1:6)*s8(8)
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cb=cmplx(cbi,cbq)
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s8r=2*s8r-1
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cbq(1:6)=pp(7:12)*s8r(1)
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cbq(7:18)=pp*s8r(3)
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cbq(19:30)=pp*s8r(5)
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cbq(31:42)=pp*s8r(7)
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cbi(1:12)=pp*s8r(2)
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cbi(13:24)=pp*s8r(4)
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cbi(25:36)=pp*s8r(6)
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cbi(37:42)=pp(1:6)*s8r(8)
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cbr=cmplx(cbi,cbq)
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call golay24_table(ig24)
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first=.false.
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endif
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! Define the 32 likely messages
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do irpt=0,31
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hashmsg=trim(mycall)//' '//trim(partnercall)//' '//rpt(irpt)
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call fmtmsg(hashmsg,iz)
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call hash(hashmsg,22,ihash)
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ihash=iand(ihash,127)
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ig=32*ihash + irpt
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likelymessages(irpt)=ig
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! write(*,*) irpt,hashmsg,ig,ig24(ig)
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enddo
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qsocontext=.false.
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! Fill the detmet, detferr arrays
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nstepsize=48 ! 4ms steps
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nstep=(n-NPTS)/nstepsize
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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+nstepsize*(istp-1)
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ne=ns+NPTS-1
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if( ne .gt. n ) exit
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ctmp=cmplx(0.0,0.0)
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ctmp(1:NPTS)=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=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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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(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(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+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( 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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detmet(istp)=max(ah,al)
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detfer(istp)=ferr
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! write(*,*) istp,ilpk,ihpk,ah,al
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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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xmed=detmet(indices(nstep/4))
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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 i=1,nstep
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!write(77,*) i,detmet(i),detfer(i)
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!enddo
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do ip=1,MAXCAND ! 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. 4.0) ) exit
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if( abs(detfer(il)) .le. 100.0 ) then
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ndet=ndet+1
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times(ndet)=((il-1)*nstepsize+NPTS/2)*dt
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ferrs(ndet)=detfer(il)
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snrs(ndet)=12.0*log10(detmet(il))/2-9.0
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endif
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detmet(max(1,il-5):min(nstep,il+5))=0.0
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! detmet(il)=0.0
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enddo
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! do ip=1,ndet
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! write(*,*) ip,times(ip),snrs(ip),ferrs(ip)
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! enddo
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nmessages=0
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allmessages=char(0)
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lines=char(0)
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imsgbest=-99
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nbadsyncbest=99
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cdbest=1e32
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cdratbest=0.0
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do ip=1,ndet !run through the candidates and try to sync/demod/decode
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imid=times(ip)*fs
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if( imid .lt. NPTS/2 ) imid=NPTS/2
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if( imid .gt. n-NPTS/2 ) imid=n-NPTS/2
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t0=times(ip)
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cdat=cbig(imid-NPTS/2+1:imid+NPTS/2)
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ferr=ferrs(ip)
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nsnr=snrs(ip)
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! remove coarse freq error - should now be within a few Hz
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call tweak1(cdat,NPTS,-(1500+ferr),cdat)
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! attempt frame synchronization
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! correlate with sync word waveforms
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ccr=0
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ccr1=0
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ccr2=0
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do i=1,NPTS-(32*6+41)
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ccr1(i)=sum(cdat(i:i+41)*conjg(cbr))
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ccr2(i)=sum(cdat(i+32*6:i+32*6+41)*conjg(cbr))
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enddo
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ccr=ccr1+ccr2
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ddr=abs(ccr1)*abs(ccr2)
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crmax=maxval(abs(ccr))
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! Find 6 largest peaks
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do ipk=1,6
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iloc=maxloc(abs(ccr))
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ic1=iloc(1)
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iloc=maxloc(ddr)
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ic2=iloc(1)
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ipeaks(ipk)=ic1
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ccr(max(1,ic1-7):min(NPTS-32*6-41,ic1+7))=0.0
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enddo
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do ipk=1,2
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! we want ic to be the index of the first sample of the frame
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ic0=ipeaks(ipk)
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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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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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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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do id=1,1 ! slicer dither.
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if( id .eq. 1 ) is=0
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if( id .eq. 2 ) is=-1
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if( id .eq. 3 ) is=1
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! Adjust frame index to place peak of bb at desired lag
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ic=ic0+ibb+is
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if( ic .lt. 1 ) ic=ic+NSPM
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! Estimate fine frequency error.
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cca=sum(cdat(ic:ic+41)*conjg(cb))
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if( ic+32*6+41 .le. NPTS ) then
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ccb=sum(cdat(ic+32*6:ic+32*6+41)*conjg(cb))
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cfac=ccb*conjg(cca)
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ferr2=atan2(imag(cfac),real(cfac))/(twopi*32*6*dt)
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else
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ccb=sum(cdat(ic-32*6:ic-32*6+41)*conjg(cb))
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cfac=cca*conjg(ccb)
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ferr2=atan2(imag(cfac),real(cfac))/(twopi*32*6*dt)
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endif
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! Final estimate of the carrier frequency - returned to the calling program
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fest=1500+ferr+ferr2
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do idf=0,6 ! frequency jitter
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if( idf .eq. 0 ) then
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deltaf=0.0
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elseif( mod(idf,2) .eq. 0 ) then
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deltaf=4*idf
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else
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deltaf=-4*(idf+1)
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endif
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! Remove fine frequency error
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call tweak1(cdat,NPTS,-(ferr2+deltaf),cdat2)
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! place the beginning of frame at index NSPM+1
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cdat2=cshift(cdat2,ic-(NSPM+1))
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do iav=1,8 ! Frame averaging patterns
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if( iav .eq. 1 ) then
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c=cdat2(NSPM+1:2*NSPM)
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elseif( iav .eq. 2 ) then
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c=cdat2(NSPM-95:NSPM+96)
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c=cshift(c,-96)
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elseif( iav .eq. 3 ) then
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c=cdat2(2*NSPM-95:2*NSPM+96)
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c=cshift(c,-96)
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elseif( iav .eq. 4 ) then
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c=cdat2(1:NSPM)
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elseif( iav .eq. 5 ) then
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c=cdat2(2*NSPM+1:3*NSPM)
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elseif( iav .eq. 6 ) then
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c=cdat2(1:NSPM)+cdat2(NSPM+1:2*NSPM)
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elseif( iav .eq. 7 ) then
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c=cdat2(NSPM+1:2*NSPM)+cdat2(2*NSPM+1:3*NSPM)
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elseif( iav .eq. 8 ) then
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c=cdat2(1:NSPM)+cdat2(NSPM+1:2*NSPM)+cdat2(2*NSPM+1:3*NSPM)
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endif
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! Estimate final frequency error and carrier phase.
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cca=sum(c(1:1+41)*conjg(cb))
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phase0=atan2(imag(cca),real(cca))
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do ipha=1,3
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if( ipha.eq.2 ) phase0=phase0-20*pi/180.0
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if( ipha.eq.3 ) phase0=phase0+20*pi/180.0
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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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if( nmatchedfilter .eq. 0 ) then
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! sample to get softsamples
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do i=1, 16
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softbits(2*i-1)=imag(c(1+(i-1)*12))
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softbits(2*i)=real(c(7+(i-1)*12))
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enddo
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else
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! matched filter -
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softbits(1)=sum(imag(c(1:6))*pp(7:12))+sum(imag(c(NSPM-5:NSPM))*pp(1:6))
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softbits(2)=sum(real(c(1:12))*pp)
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do i=2,16
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softbits(2*i-1)=sum(imag(c(1+(i-1)*12-6:1+(i-1)*12+5))*pp)
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softbits(2*i)=sum(real(c(7+(i-1)*12-6:7+(i-1)*12+5))*pp)
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enddo
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endif
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! sync word hard error weight is a good discriminator for
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! frames that have reasonable probability of decoding
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hardbits=0
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do i=1, 32
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if( softbits(i) .ge. 0.0 ) then
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hardbits(i)=1
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endif
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enddo
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nbadsync1=(8-sum( (2*hardbits(1:8)-1)*s8r ) )/2
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nbadsync=nbadsync1
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if( nbadsync .gt. 3 ) cycle
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! normalize the softsymbols before submitting to decoder
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sav=sum(softbits)/32
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s2av=sum(softbits*softbits)/32
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ssig=sqrt(s2av-sav*sav)
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softbits=softbits/ssig
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if( qsocontext ) then
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! search 32 likely messages only, using correlation discrepancy
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cd=1e6
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ihammd=99
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do i=0,31
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ncw=ig24(likelymessages(i))
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cd(i)=0.0
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ihammd(i)=0
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do ii=1,24
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ib=iand(1,ishft(ncw,1-ii))
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ib=2*ib-1
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if( ib*softbits(ii+8) .lt. 0 ) cd(i)=cd(i)+abs(softbits(ii+8))
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if( ib*(2*hardbits(ii+8)-1) .lt. 0 ) ihammd(i)=ihammd(i)+1
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enddo
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enddo
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else
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! exhaustive search decoder, using correlation discrepancy
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cd=1e6
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ihammd=99
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do i=0,4096-1
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ncw=ig24(i)
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cd(i)=0.0
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ihammd(i)=0
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do ii=1,24
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ib=iand(1,ishft(ncw,1-ii))
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ib=2*ib-1
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if( ib*softbits(ii+8) .lt. 0 ) cd(i)=cd(i)+abs(softbits(ii+8))
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if( ib*(2*hardbits(ii+8)-1) .lt. 0 ) ihammd(i)=ihammd(i)+1
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enddo
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enddo
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endif
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cdm=minval(cd)
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iloc=minloc(cd)
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imsg=iloc(1)-1
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cd(imsg)=1e6
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cdm2=minval(cd)
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iloc=minloc(cd)
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imsg2=iloc(1)-1
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cdrat=cdm2/(cdm+0.001)
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! if( cdrat .gt. cdratbest ) then
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if( cdm .lt. cdbest ) then
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cdratbest = cdrat
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cdbest = cdm
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imsgbest = imsg
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iavbest = iav
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ipbest = ip
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ipkbest = ipk
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idfbest = idf
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idbest = id
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iphabest = ipha
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nbadsyncbest = nbadsync
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if( ( ihammd(imsgbest)+nbadsyncbest .le. 4 ) .and. ( (cdratbest .gt. 100.0) .and. (cdbest .le. 0.05) ) ) goto 999
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endif
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enddo ! phase loop
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enddo ! frame averaging loop
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enddo ! frequency dithering loop
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enddo ! sample-time dither loop
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enddo ! peak loop
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! write(78,1001) nutc,t0,nsnr,ic,ipk,is,idf,iav,deltaf,fest,ferr,ferr2,ffin,bba,bbp,nbadsync, &
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! phase0,msgreceived
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! call flush(78)
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!1001 format(i6.6,f8.2,i5,i5,i5,i5,i5,i5,f8.2,f8.2,f8.2,f8.2,f8.2,f10.2,f8.2,i5,f8.2,2x,a22)
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enddo
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999 continue
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msgreceived=' '
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if( imsgbest .gt. 0 ) then
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if( ( ihammd(imsgbest)+nbadsyncbest .le. 4 ) .and. (cdratbest .gt. 50.0) .and. (cdbest .le. 0.05) ) then
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if( qsocontext ) then
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nrxrpt=iand(likelymessages(imsgbest),31)
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nrxhash=(likelymessages(imsgbest)-nrxrpt)/32
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imessage=likelymessages(imsgbest)
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else
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nrxrpt=iand(imsgbest,31)
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nrxhash=(imsgbest-nrxrpt)/32
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imessage=imsgbest
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endif
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! See if this message has a hash that is expected for a message sent to mycall by partnercall
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hashmsg=trim(mycall)//' '//trim(partnercall)//' '//rpt(nrxrpt)
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call fmtmsg(hashmsg,iz)
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call hash(hashmsg,22,ihash)
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ihash=iand(ihash,127)
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if( nrxhash .eq. ihash ) then
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nmessages=1
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write(msgreceived,'(a1,a,1x,a,a1,1x,a4)') "<",trim(mycall),trim(partnercall),">",rpt(nrxrpt)
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write(lines(nmessages),1020) nutc,nsnr,t0,nint(fest),msgreceived
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1020 format(i6.6,i4,f5.1,i5,' & ',a22)
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! write(*,1022) nutc,ipbest,times(ipbest),snrs(ipbest),fest,nrxrpt,nrxhash, &
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! rpt(nrxrpt),imessage,ig24(imessage),ihammd(imsgbest), &
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! cdbest,cdratbest,nbadsyncbest,ipkbest,idbest,idfbest,iavbest,iphabest
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endif
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endif
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endif
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!1022 format(i4.4,2x,i4,f8.3,f8.2,f8.2,i6,i6,a6,i8,i10,i4,f8.2,f8.2,i5,i5,i5,i5,i5,i5)
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return
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end subroutine detectmsk32
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