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Use quarter-symbol steps for time sync. Lower sync threshold. Implement subtraction and two pass decoding. Use osd2 only near nfqso. 

git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@7861 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
This commit is contained in:
Steven Franke 2017-07-12 21:49:39 +00:00
parent bfa2c73c6c
commit d8f9f385b4
8 changed files with 127 additions and 98 deletions
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2
lib/fsk4hf/bpdecode174.f90
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@ -1,4 +1,4 @@
subroutine bpdecode174(llr,apmask,maxiterations,decoded,cw,nharderror)
subroutine bpdecode174(llr,apmask,maxiterations,decoded,cw,nharderror,iter)
!
! A log-domain belief propagation decoder for the (174,87) code.
!

3
lib/fsk4hf/ft8_params.f90
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@ -7,5 +7,6 @@ parameter (NSPS=1920) !Samples per symbol at 12000 S/s
parameter (NZ=NSPS*NN) !Samples in full 15 s waveform (151,680)
parameter (NMAX=15*12000) !Samples in iwave (180,000)
parameter (NFFT1=2*NSPS, NH1=NFFT1/2) !Length of FFTs for symbol spectra
parameter (NHSYM=2*NMAX/NH1-1) !Number of symbol spectra (1/2-sym steps)
parameter (NSTEP=NSPS/4) !Rough time-sync step size
parameter (NHSYM=NMAX/NSTEP-1) !Number of symbol spectra (1/2-sym steps)
parameter (NDOWN=60) !Downsample factor

52
lib/fsk4hf/ft8b.f90
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@ -1,5 +1,5 @@
subroutine ft8b(dd0,newdat,nfqso,ndepth,icand,sync0,f1,xdt,apsym,nharderrors, &
dmin,nbadcrc,message,xsnr)
subroutine ft8b(dd0,newdat,nfqso,ndepth,lsubtract,icand,sync0,f1,xdt,apsym,nharderrors, &
dmin,nbadcrc,iap,ipass,message,xsnr)
use timer_module, only: timer
include 'ft8_params.f90'
@ -18,12 +18,12 @@ subroutine ft8b(dd0,newdat,nfqso,ndepth,icand,sync0,f1,xdt,apsym,nharderrors,
complex cd0(3200)
complex ctwk(32)
complex csymb(32)
logical newdat
logical newdat,lsubtract
data rr73/-1,1,1,1,1,1,1,-1,1,1,-1/
max_iterations=40
max_iterations=30
norder=2
if(ndepth.eq.3 .and. abs(nfqso-f1).lt.10.0) norder=3
nharderrors=-1
fs2=12000.0/NDOWN
dt2=1.0/fs2
twopi=8.0*atan(1.0)
@ -36,7 +36,7 @@ subroutine ft8b(dd0,newdat,nfqso,ndepth,icand,sync0,f1,xdt,apsym,nharderrors,
i0=nint(xdt*fs2) !Initial guess for start of signal
smax=0.0
do idt=i0-16,i0+16 !Search over +/- half a symbol
do idt=i0-8,i0+8 !Search over +/- one quarter symbol
call sync8d(cd0,idt,ctwk,0,sync)
if(sync.gt.smax) then
smax=sync
@ -109,30 +109,34 @@ subroutine ft8b(dd0,newdat,nfqso,ndepth,icand,sync0,f1,xdt,apsym,nharderrors,
rxdata=rxdata/rxsig
ss=0.84
llr=2.0*rxdata/(ss*ss)
! do iap=0,3
apmag=4.0
! do iap=0,1
do iap=0,0 !### Temporary ###
if(iap.eq.0) then
apmask=0
apmask(160:162)=1
llrap=llr
llrap(160:162)=5.0*apsym(73:75)/ss
llrap(160:162)=apmag*apsym(73:75)/ss
elseif(iap.eq.1) then
apmask=0
apmask(88:115)=1 ! mycall
apmask(144)=1 ! not free text
apmask(160:162)=1 ! 3 extra bits
llrap=0.0
llrap(88:115)=5.0*apsym(1:28)/ss
llrap(160:162)=5.0*apsym(73:75)/ss
llrap(88:115)=apmag*apsym(1:28)/ss
llrap(144)=-apmag/ss
llrap(160:162)=apmag*apsym(73:75)/ss
where(apmask.eq.0) llrap=llr
elseif(iap.eq.2) then
apmask=0
apmask(88:115)=1 ! mycall
apmask(116:143)=1 ! hiscall
apmask(144)=1 ! not free text
apmask(160:162)=1 ! 3 extra bits
llrap=0.0
llrap(88:143)=5.0*apsym(1:56)/ss
llrap(160:162)=5.0*apsym(73:75)/ss
llrap(88:143)=apmag*apsym(1:56)/ss
llrap(144)=-apmag/ss
llrap(160:162)=apmag*apsym(73:75)/ss
where(apmask.eq.0) llrap=llr
elseif(iap.eq.3) then
apmask=0
@ -141,26 +145,28 @@ subroutine ft8b(dd0,newdat,nfqso,ndepth,icand,sync0,f1,xdt,apsym,nharderrors,
apmask(144:154)=1 ! RRR or 73
apmask(160:162)=1 ! 3 extra bits
llrap=0.0
llrap(88:143)=5.0*apsym(1:56)/ss
llrap(144:154)=5.0*rr73/ss
llrap(160:162)=5.0*apsym(73:75)/ss
llrap(88:143)=apmag*apsym(1:56)/ss
llrap(144:154)=apmag*rr73/ss
llrap(160:162)=apmag*apsym(73:75)/ss
where(apmask.eq.0) llrap=llr
endif
cw=0
call timer('bpd174 ',0)
call bpdecode174(llrap,apmask,max_iterations,decoded,cw,nharderrors)
call bpdecode174(llrap,apmask,max_iterations,decoded,cw,nharderrors,niterations)
call timer('bpd174 ',1)
dmin=0.0
if(nharderrors.lt.0 .and. ndepth.ge.2) then
if(ndepth.eq.3 .and. abs(nfqso-f1).lt.10.0 .and. nharderrors.lt.0) then
call timer('osd174 ',0)
call osd174(llrap,norder,decoded,cw,nharderrors,dmin)
call osd174(llrap,apmask,norder,decoded,cw,nharderrors,dmin)
call timer('osd174 ',1)
endif
nbadcrc=1
message=' '
xsnr=-99.0
if(count(cw.eq.0).eq.174) cycle !Reject the all-zero codeword
if( nharderrors.ge.0 .and. dmin.le.30.0 .and. nharderrors .lt. 30) then
! if( nharderrors.ge.0 .and. dmin.le.30.0 .and. nharderrors .lt. 30) then
!*** These thresholds should probably be dependent on nap
if( nharderrors.ge.0 .and. dmin.le.50.0 .and. nharderrors .lt. 50) then
call chkcrc12a(decoded,nbadcrc)
else
nharderrors=-1
@ -169,7 +175,7 @@ subroutine ft8b(dd0,newdat,nfqso,ndepth,icand,sync0,f1,xdt,apsym,nharderrors,
if(nbadcrc.eq.0) then
call extractmessage174(decoded,message,ncrcflag,recent_calls,nrecent)
call genft8(message,msgsent,msgbits,itone)
! call subtractft8(dd0,itone,f1,xdt2)
if(lsubtract) call subtractft8(dd0,itone,f1,xdt2)
xsig=0.0
xnoi=0.0
do i=1,79
@ -181,8 +187,8 @@ subroutine ft8b(dd0,newdat,nfqso,ndepth,icand,sync0,f1,xdt,apsym,nharderrors,
if( xnoi.gt.0 .and. xnoi.lt.xsig ) xsnr=xsig/xnoi-1.0
xsnr=10.0*log10(xsnr)-27.0
if( xsnr .lt. -24.0 ) xsnr=-24.0
! write(50,3050) icand,sync0,f1,xdt,nharderrors,dmin,message,iap
!3050 format(i3,3f10.3,i5,f10.3,2x,a22,i3)
! write(50,3050) icand,sync0,f1,xdt,xsnr,nharderrors,niterations,dmin,iap,ipass,message
!3050 format(i3,4f10.3,i5,i5,f10.3,i4,i4,2x,a22)
return
endif
enddo

38
lib/fsk4hf/osd174.f90
View File

@ -1,9 +1,10 @@
subroutine osd174(llr,norder,decoded,cw,nhardmin,dmin)
subroutine osd174(llr,apmask,norder,decoded,cw,nhardmin,dmin)
!
! An ordered-statistics decoder for the (174,87) code.
!
include "ldpc_174_87_params.f90"
integer*1 apmask(N),apmaskr(N)
integer*1 gen(K,N)
integer*1 genmrb(K,N),g2(N,K)
integer*1 temp(K),m0(K),me(K),mi(K)
@ -36,6 +37,8 @@ endif
! re-order received vector to place systematic msg bits at the end
rx=llr(colorder+1)
apmaskr=apmask(colorder+1)
! hard decode the received word
hdec=0
@ -91,6 +94,7 @@ hdec=hdec(indices) ! hard decisions from received symbols
m0=hdec(1:K) ! zero'th order message
absrx=absrx(indices)
rx=rx(indices)
apmaskr=apmaskr(indices)
s1=sum(absrx(1:K))
s2=sum(absrx(K+1:N))
@ -110,22 +114,24 @@ do iorder=1,norder
mi(K-iorder+1:K)=1
iflag=0
do while(iflag .ge. 0 )
dpat=sum(mi*absrx(1:K))
nt=nt+1
if( dpat .lt. thresh ) then ! reject unlikely error patterns
me=ieor(m0,mi)
call mrbencode(me,ce,g2,N,K)
nxor=ieor(ce,hdec)
dd=sum(nxor*absrx)
if( dd .lt. dmin ) then
dmin=dd
cw=ce
nhardmin=sum(nxor)
thresh=rho*dmin
if(all(iand(apmaskr(1:K),mi).eq.0)) then ! reject patterns with ap bits
dpat=sum(mi*absrx(1:K))
nt=nt+1
if( dpat .lt. thresh ) then ! reject unlikely error patterns
me=ieor(m0,mi)
call mrbencode(me,ce,g2,N,K)
nxor=ieor(ce,hdec)
dd=sum(nxor*absrx)
if( dd .lt. dmin ) then
dmin=dd
cw=ce
nhardmin=sum(nxor)
thresh=rho*dmin
endif
else
nrejected=nrejected+1
endif
else
nrejected=nrejected+1
endif
endif
! get the next test error pattern, iflag will go negative
! when the last pattern with weight iorder has been generated
call nextpat(mi,k,iorder,iflag)

2
lib/fsk4hf/subtractft8.f90
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@ -10,7 +10,7 @@ subroutine subtractft8(dd,itone,f0,dt)
use timer_module, only: timer
parameter (NMAX=15*12000,NFRAME=1920*79)
parameter (NFFT=NMAX,NFILT=400)
parameter (NFFT=NMAX,NFILT=1400)
real*4 dd(NMAX), window(-NFILT/2:NFILT/2)
complex cref,camp,cfilt,cw
integer itone(79)

50
lib/fsk4hf/sync8.f90
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@ -1,7 +1,7 @@
subroutine sync8(dd,nfa,nfb,nfqso,s,candidate,ncand)
subroutine sync8(dd,nfa,nfb,syncmin,nfqso,s,candidate,ncand)
include 'ft8_params.f90'
parameter (JZ=31) !DT up to +/- 2.5 s
parameter (JZ=62) !DT up to +/- 1.25 s
complex cx(0:NH1)
real s(NH1,NHSYM)
real savg(NH1)
@ -18,16 +18,13 @@ subroutine sync8(dd,nfa,nfb,nfqso,s,candidate,ncand)
data icos7/2,5,6,0,4,1,3/ !Costas 7x7 tone pattern
equivalence (x,cx)
! Compute symbol spectra at half-symbol steps.
! Compute symbol spectra, stepping by NSTEP steps.
savg=0.
istep=NSPS/2 !960
tstep=istep/12000.0 !0.08 s
tstep=NSTEP/12000.0
df=12000.0/NFFT1 !3.125 Hz
! Compute symbol spectra at half-symbol steps
fac=1.0/300.0
do j=1,NHSYM
ia=(j-1)*istep + 1
ia=(j-1)*NSTEP + 1
ib=ia+NSPS-1
x(1:NSPS)=fac*dd(ia:ib)
x(NSPS+1:)=0.
@ -45,21 +42,23 @@ subroutine sync8(dd,nfa,nfb,nfqso,s,candidate,ncand)
ia=max(1,nint(nfa/df))
ib=nint(nfb/df)
nssy=NSPS/NSTEP ! # steps per symbol
nfos=NFFT1/NSPS ! # frequency bin oversampling factor
do i=ia,ib
do j=-JZ,JZ
t=0.
t0=0.
do n=0,6
k=j+2*n
if(k.ge.1) then
t=t + s(i+2*icos7(n),k)
t0=t0 + sum(s(i:i+12:2,k))
k=j+nssy*n
if(k.ge.1.and.k.le.NHSYM) then
t=t + s(i+nfos*icos7(n),k)
t0=t0 + sum(s(i:i+nfos*6:nfos,k))
endif
t=t + s(i+2*icos7(n),k+72)
t0=t0 + sum(s(i:i+12:2,k+72))
t=t + s(i+nfos*icos7(n),k+nssy*36)
t0=t0 + sum(s(i:i+nfos*6:nfos,k+nssy*36))
if(k+144.le.NHSYM) then
t=t + s(i+2*icos7(n),k+144)
t0=t0 + sum(s(i:i+12:2,k+144))
t=t + s(i+nfos*icos7(n),k+nssy*72)
t0=t0 + sum(s(i:i+nfos*6:nfos,k+nssy*72))
endif
enddo
t0=(t0-t)/6.0
@ -84,8 +83,7 @@ subroutine sync8(dd,nfa,nfb,nfqso,s,candidate,ncand)
candidate0=0.
k=0
syncmin=2.0
do i=1,100
do i=1,200
n=ia + indx(iz+1-i) - 1
if(red(n).lt.syncmin) exit
if(k.lt.200) k=k+1
@ -115,13 +113,21 @@ subroutine sync8(dd,nfa,nfb,nfqso,s,candidate,ncand)
fac=20.0/maxval(s)
s=fac*s
! Sort by sync
! call indexx(candidate0(3,1:ncand),ncand,indx)
! Sort by frequency
call indexx(candidate0(1,1:ncand),ncand,indx)
k=1
! do i=ncand,1,-1
do i=1,ncand
j=indx(i)
candidate(1,i)=abs(candidate0(1,j))
candidate(2,i)=candidate0(2,j)
candidate(3,i)=candidate0(3,j)
if( candidate0(3,j) .ge. syncmin ) then
candidate(1,k)=abs(candidate0(1,j))
candidate(2,k)=candidate0(2,j)
candidate(3,k)=candidate0(3,j)
k=k+1
endif
enddo
ncand=k-1
return
end subroutine sync8

76
lib/ft8_decode.f90
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@ -24,17 +24,18 @@ contains
subroutine decode(this,callback,iwave,nfqso,newdat,nutc,nfa, &
nfb,nagain,ndepth,nsubmode,mycall12,hiscall12,hisgrid6)
!use wavhdr
! use wavhdr
use timer_module, only: timer
include 'fsk4hf/ft8_params.f90'
!type(hdr) h
! type(hdr) h
class(ft8_decoder), intent(inout) :: this
procedure(ft8_decode_callback) :: callback
real s(NH1,NHSYM)
real candidate(3,200)
real dd(15*12000)
logical, intent(in) :: newdat, nagain
logical, intent(in) :: nagain
logical newdat,lsubtract
character*12 mycall12, hiscall12
character*6 hisgrid6
integer*2 iwave(15*12000)
@ -50,38 +51,47 @@ contains
call ft8apset(mycall12,hiscall12,hisgrid6,apsym)
dd=iwave
call timer('sync8 ',0)
call sync8(dd,nfa,nfb,nfqso,s,candidate,ncand)
call timer('sync8 ',1)
syncmin=2.0
do icand=1,ncand
sync=candidate(3,icand)
if(sync.lt.syncmin) cycle
f1=candidate(1,icand)
xdt=candidate(2,icand)
nsnr0=min(99,nint(10.0*log10(sync) - 25.5)) !### empirical ###
call timer('ft8b ',0)
call ft8b(dd,newdat,nfqso,ndepth,icand,sync,f1,xdt,apsym,nharderrors, &
dmin,nbadcrc,message,xsnr)
nsnr=xsnr
xdt=xdt-0.6
call timer('ft8b ',1)
if (associated(this%callback)) call this%callback(sync,nsnr,xdt, &
! For now:
! ndepth=1: no subtraction, 1 pass, belief propagation only
! ndepth=2: subtraction, 2 passes, belief propagation only
! ndepth=3: subtraction, 2 passes, bp+osd2 at and near nfqso
if(ndepth.eq.1) npass=1
if(ndepth.ge.2) npass=2
do ipass=1,npass
newdat=.true. ! Is this a problem? I hijacked newdat.
if(ipass.eq.1) then
lsubtract=.true.
if(ndepth.eq.1) lsubtract=.false.
syncmin=1.3
else
lsubtract=.false.
syncmin=1.3
endif
call timer('sync8 ',0)
call sync8(dd,nfa,nfb,syncmin,nfqso,s,candidate,ncand)
call timer('sync8 ',1)
do icand=1,ncand
sync=candidate(3,icand)
f1=candidate(1,icand)
xdt=candidate(2,icand)
nsnr0=min(99,nint(10.0*log10(sync) - 25.5)) !### empirical ###
call timer('ft8b ',0)
call ft8b(dd,newdat,nfqso,ndepth,lsubtract,icand,sync,f1,xdt,apsym,nharderrors, &
dmin,nbadcrc,iap,ipass,message,xsnr)
nsnr=xsnr
xdt=xdt-0.6
call timer('ft8b ',1)
if (associated(this%callback)) call this%callback(sync,nsnr,xdt, &
f1,nbadcrc,message)
! write(*,'(f7.2,i5,f7.2,f9.1,i5,f7.2,2x,a22)') sync,nsnr,xdt,f1,nharderrors,dmin,message
! write(13,1110) datetime,0,nsnr,xdt,f1,nharderrors,dmin,message
!1110 format(a13,2i4,f6.2,f7.1,i4,' ~ ',f6.2,2x,a22,' FT8')
! write(51,3051) xdt,f1,sync,dmin,nsnr,nharderrors,nbadcrc,message
!3051 format(4f9.1,3i5,2x,a22)
! flush(51)
enddo
!h=default_header(12000,NMAX)
!open(10,file='subtract.wav',status='unknown',access='stream')
!iwave=nint(dd)
!write(10) h,iwave
!close(10)
return
enddo
! h=default_header(12000,NMAX)
! open(10,file='subtract.wav',status='unknown',access='stream')
! iwave=nint(dd)
! write(10) h,iwave
! close(10)
enddo
return
end subroutine decode
end module ft8_decode

2
lib/jt9.f90
View File

@ -262,7 +262,7 @@ program jt9
shared_data%params%ndepth=ndepth
shared_data%params%dttol=3.
shared_data%params%minsync=0 !### TEST ONLY
! shared_data%params%minsync=0 !### TEST ONLY
! shared_data%params%nfqso=1500 !### TEST ONLY
! mycall="G3WDG " !### TEST ONLY
! hiscall="VK7MO " !### TEST ONLY