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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 2016-06-22 02:29:37 +00:00
parent 0bd4a2363a
commit 403f16d296
3 changed files with 68 additions and 37 deletions
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4
lib/analytic.f90
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@ -13,7 +13,7 @@ subroutine analytic(d,npts,nfft,c)
nh=nfft/2
if(nfft.ne.nfft0) then
t=1.0/2000.0
beta=0.6
beta=0.1
pi=4.0*atan(1.0)
do i=1,nh+1
ff=(i-1)*df
@ -23,7 +23,7 @@ subroutine analytic(d,npts,nfft,c)
if(abs(f).gt.(1-beta)/(2*t) .and. abs(f).le.(1+beta)/(2*t)) then
h(i)=0.5*(1+cos((pi*t/beta )*(abs(f)-(1-beta)/(2*t))))
endif
h(i)=sqrt(h(i))
! h(i)=sqrt(h(i))
enddo
nfft0=nfft
endif

100
lib/detectmsk144.f90
View File

@ -1,7 +1,7 @@
subroutine detectmsk144(cbig,n,pchk_file,lines,nmessages,nutc)
use timer_module, only: timer
parameter (NSPM=864, NPTS=3*NSPM, MAXSTEPS=1500)
parameter (NSPM=864, NPTS=3*NSPM, MAXSTEPS=1700, NFFT=NSPM)
character*22 msgreceived,allmessages(20)
character*80 lines(100)
character*512 pchk_file,gen_file
@ -9,7 +9,7 @@ subroutine detectmsk144(cbig,n,pchk_file,lines,nmessages,nutc)
complex cdat(NPTS) !Analytic signal
complex cdat2(NPTS)
complex c(NSPM)
complex ctmp(6000)
complex ctmp(NFFT)
complex cb(42) !Complex waveform for sync word
complex cfac,cca,ccb
complex cc(NPTS)
@ -21,17 +21,18 @@ subroutine detectmsk144(cbig,n,pchk_file,lines,nmessages,nutc)
integer*1 decoded(80)
integer indices(MAXSTEPS)
integer ipeaks(10)
logical ismask(6000)
logical ismask(NFFT)
real cbi(42),cbq(42)
real detmet(-2:MAXSTEPS+3)
real detfer(MAXSTEPS)
real tonespec(6000)
real hannwindow(NPTS)
real rcw(12)
real dd(NPTS)
real ferrs(20)
real pp(12) !Half-sine pulse shape
real snrs(20)
real times(20)
real tonespec(NFFT)
real*8 dt, df, fs, pi, twopi
real softbits(144)
real*8 unscrambledsoftbits(128)
@ -39,7 +40,7 @@ subroutine detectmsk144(cbig,n,pchk_file,lines,nmessages,nutc)
logical first
data first/.true./
data s8/0,1,1,1,0,0,1,0/
save df,first,cb,fs,nfft,pi,twopi,dt,s8,rcw,pp
save df,first,cb,fs,pi,twopi,dt,s8,rcw,pp,hannwindow
if(first) then
nmatchedfilter=1
@ -51,8 +52,7 @@ subroutine detectmsk144(cbig,n,pchk_file,lines,nmessages,nutc)
twopi=8d0*datan(1d0)
fs=12000.0
dt=1.0/fs
nfft=6000 !using a zero-padded fft to get 2 Hz bins
df=fs/nfft
df=fs/NFFT
do i=1,12
angle=(i-1)*pi/12.0
@ -60,6 +60,10 @@ subroutine detectmsk144(cbig,n,pchk_file,lines,nmessages,nutc)
rcw(i)=(1-cos(angle))/2
enddo
do i=1,NPTS
hannwindow(i)=0.5*(1-cos(twopi*(i-1)/NPTS))
enddo
! define the sync word waveform
s8=2*s8-1
cbq(1:6)=pp(7:12)*s8(1)
@ -76,66 +80,87 @@ subroutine detectmsk144(cbig,n,pchk_file,lines,nmessages,nutc)
endif
! fill the detmet, detferr arrays
nstep=(n-NSPM)/256
nstep=(n-NPTS)/216 ! 72ms/4=18ms steps
detmet=0
detmax=-999.99
detfer=-999.99
do istp=1,nstep
ns=1+256*(istp-1)
ne=ns+NPTS-1
ns=1+216*(istp-1)
ne=ns+NSPM-1
if( ne .gt. n ) exit
cdat=cbig(ns:ne)
ctmp=cmplx(0.0,0.0)
ctmp(1:NSPM)=cbig(ns:ne)
! Coarse carrier frequency sync - seek tones at 2000 Hz and 4000 Hz in
! squared signal spectrum.
! search range for coarse frequency error is +/- 100 Hz
ctmp=cmplx(0.0,0.0)
ctmp(1:NPTS)=cdat**2
ctmp=ctmp**2
ctmp(1:12)=ctmp(1:12)*rcw
ctmp(NPTS-11:NPTS)=ctmp(NPTS-11:NPTS)*rcw(12:1:-1)
call four2a(ctmp,nfft,1,-1,1)
ctmp(NSPM-11:NSPM)=ctmp(NSPM-11:NSPM)*rcw(12:1:-1)
! ctmp(1:NSPM)=ctmp(1:NSPM)*hannwindow
call four2a(ctmp,NFFT,1,-1,1)
tonespec=abs(ctmp)**2
i3800=3800/df+1
i4200=4200/df+1
ismask=.false.
ismask(1901:2101)=.true. ! high tone search window
ismask(i3800:i4200)=.true. ! high tone search window
iloc=maxloc(tonespec,ismask)
ihpk=iloc(1)
deltah=-real( (ctmp(ihpk-1)-ctmp(ihpk+1)) / (2*ctmp(ihpk)-ctmp(ihpk-1)-ctmp(ihpk+1)) )
ah=tonespec(ihpk)
i1800=1800/df+1
i2200=2200/df+1
ismask=.false.
ismask(901:1101)=.true. ! window for low tone
ismask(i1800:i2200)=.true. ! window for low tone
iloc=maxloc(tonespec,ismask)
ilpk=iloc(1)
deltal=-real( (ctmp(ilpk-1)-ctmp(ilpk+1)) / (2*ctmp(ilpk)-ctmp(ilpk-1)-ctmp(ilpk+1)) )
al=tonespec(ilpk)
fdiff=(ihpk-ilpk)*df
ferrh=(ihpk-2001)*df/2.0
ferrl=(ilpk-1001)*df/2.0
if( abs(fdiff-2000) .le. 16.0 ) then
fdiff=(ihpk+deltah-ilpk-deltal)*df
i2000=2000/df+1
i4000=4000/df+1
ferrh=(ihpk+deltah-i4000)*df/2.0
ferrl=(ilpk+deltal-i2000)*df/2.0
! if( abs(fdiff-2000) .le. 25.0 ) then
if( ah .ge. al ) then
ferr=ferrh
else
ferr=ferrl
endif
else
ferr=-999.99
endif
detmet(istp)=ah+al
! else
! ferr=-999.99
! endif
! detmet(istp)=ah+al
detmet(istp)=max(ah,al)
detfer(istp)=ferr
! if( detmet(istp) .gt. detmax ) then
! open(unit=77,file="tonespec.dat")
! do i=1,NFFT
! write(77,*) (i-1)*df,tonespec(i)
! enddo
! close(77)
! detmax=detmet(istp)
! endif
!write(*,*) ihpk,ilpk,deltah,deltal,ferrh,ferrl,fdiff
enddo ! end of detection-metric and frequency error estimation loop
call indexx(detmet(1:nstep),nstep,indices) !find median of detection metric vector
xmed=detmet(indices(nstep/2))
detmet=detmet/xmed ! noise floor of detection metric is 1.0
ndet=0
do ip=1,20 ! use something like the "clean" algorithm to find candidates
iloc=maxloc(detmet(1:nstep))
il=iloc(1)
if( (detmet(il) .lt. 1.5) .or. (abs(detfer(il)) .gt. 100.0) ) cycle
if( (detmet(il) .lt. 2.0) .or. (abs(detfer(il)) .gt. 100.0) ) cycle
ndet=ndet+1
times(ndet)=((il-1)*256+NPTS/2)*dt
times(ndet)=((il-1)*216+NSPM/2)*dt
ferrs(ndet)=detfer(il)
snrs(ndet)=10.0*log10(detmet(il))/2-5.0 !/2 because detmet is a 4th order moment
detmet(il-3:il+3)=0.0
! write(*,*) ndet,"snr ",snrs(ndet),"ferr ",ferrs(ndet)
enddo
nmessages=0
@ -182,14 +207,15 @@ subroutine detectmsk144(cbig,n,pchk_file,lines,nmessages,nutc)
! fine adjustment of sync index
do i=1,6
if( ic0+11+NSPM .le. NPTS ) then
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 )
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 )
else
bb(i) = sum( ( cdat(ic0+i-1+6:NPTS:6) * conjg( cdat(ic0+i-1:NPTS-6:6) ) )*2 )
bb(i) = sum( ( cdat(ic0+i-1+6:NPTS:6) * conjg( cdat(ic0+i-1:NPTS-6:6) ) )**2 )
endif
enddo
iloc=maxloc(abs(bb))
ibb=iloc(1)
bba=abs(bb(ibb))
bbp=atan2(-imag(bb(ibb)),-real(bb(ibb)))/(2*twopi*6*dt)
if( ibb .le. 3 ) ibb=ibb-1
if( ibb .gt. 3 ) ibb=ibb-7
@ -260,7 +286,7 @@ subroutine detectmsk144(cbig,n,pchk_file,lines,nmessages,nutc)
cfac=ccb*conjg(cca)
ffin=atan2(imag(cfac),real(cfac))/(twopi*56*6*dt)
phase0=atan2(imag(cca+ccb),real(cca+ccb))
! Remove phase error - want constellation rotated so that sample points lie on I/Q axes
cfac=cmplx(cos(phase0),sin(phase0))
c=c*conjg(cfac)
@ -293,7 +319,7 @@ subroutine detectmsk144(cbig,n,pchk_file,lines,nmessages,nutc)
nbadsync1=(8-sum( (2*hardbits(1:8)-1)*s8 ) )/2
nbadsync2=(8-sum( (2*hardbits(1+56:8+56)-1)*s8 ) )/2
nbadsync=nbadsync1+nbadsync2
if( nbadsync .gt. 6 ) cycle
if( nbadsync .gt. 4 ) cycle
! normalize the softsymbols before submitting to decoder
sav=sum(softbits)/144
@ -331,7 +357,7 @@ subroutine detectmsk144(cbig,n,pchk_file,lines,nmessages,nutc)
else
msgreceived=' '
ndither=-99 ! -99 is bad hash flag
! write(78,1001) nutc,t0,nsnr,ipk,is,idf,iav,deltaf,fest,ffin,nbadsync1,nbadsync2, &
! write(78,1001) nutc,t0,nsnr,ipk,is,idf,iav,deltaf,fest,ferr,ferr2,ffin,bba,bbp,nbadsync1,nbadsync2, &
! phase0,niterations,ndither,msgreceived
endif
endif
@ -343,9 +369,13 @@ subroutine detectmsk144(cbig,n,pchk_file,lines,nmessages,nutc)
msgreceived=' '
ndither=-98
999 continue
! write(78,1001) nutc,t0,nsnr,ipk,is,idf,iav,deltaf,fest,ffin,nbadsync1,nbadsync2, &
if( nmessages .ge. 1 ) then
! write(78,1001) nutc,t0,nsnr,ipk,is,idf,iav,deltaf,fest,ferr,ferr2,ffin,bba,bbp,nbadsync1,nbadsync2, &
! phase0,niterations,ndither,msgreceived
!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)
! call flush(78)
!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)
exit
endif
enddo
return
end subroutine detectmsk144

1
lib/msk144sim.f90
View File

@ -67,6 +67,7 @@ program msk144sim
call makepings(pings,NMAX,width,sig)
! call sgran()
do ifile=1,nfiles !Loop over requested number of files
write(fname,1002) ifile !Output filename
1002 format('000000_',i6.6)