WSJT-X/lib/fsk4hf/ft8b.f90
Steven Franke bbbcae9233 Add variables lapon and napwid to control ap decoding. Reconfigure the logic for AP decoding and ordered-statistics decoding.
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@7933 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
2017-07-22 03:01:09 +00:00

283 lines
9.3 KiB
Fortran

subroutine ft8b(dd0,newdat,nfqso,ndepth,lapon,napwid,lsubtract,iaptype,icand, &
sync0,f1,xdt,apsym,nharderrors,dmin,nbadcrc,iap,ipass,iera,message,xsnr)
use timer_module, only: timer
include 'ft8_params.f90'
parameter(NRECENT=10,NP2=2812)
character message*22,msgsent*22
character*12 recent_calls(NRECENT)
real a(5)
real s1(0:7,ND),s2(0:7,NN)
real ps(0:7)
real rxdata(3*ND),rxdatap(3*ND)
real llr(3*ND),llra(3*ND),llr0(3*ND),llrap(3*ND) !Soft symbols
real dd0(15*12000)
integer*1 decoded(KK),apmask(3*ND),cw(3*ND)
integer*1 msgbits(KK)
integer apsym(KK),rr73(11),cq(28)
integer itone(NN)
complex cd0(3200)
complex ctwk(32)
complex csymb(32)
logical newdat,lsubtract,lapon
data rr73/-1,1,1,1,1,1,1,-1,1,1,-1/
data cq/1,1,1,1,1,-1,1,-1,-1,-1,-1,-1,1,-1,-1,-1,-1,-1,1,1,-1,-1,-1,1,1,-1,-1,1/
max_iterations=30
nharderrors=-1
fs2=12000.0/NDOWN
dt2=1.0/fs2
twopi=8.0*atan(1.0)
delfbest=0.
ibest=0
call timer('ft8_down',0)
call ft8_downsample(dd0,newdat,f1,cd0) !Mix f1 to baseband and downsample
call timer('ft8_down',1)
i0=nint((xdt+0.5)*fs2) !Initial guess for start of signal
smax=0.0
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
ibest=idt
endif
enddo
xdt2=ibest*dt2 !Improved estimate for DT
! Now peak up in frequency
i0=nint(xdt2*fs2)
smax=0.0
do ifr=-5,5 !Search over +/- 2.5 Hz
delf=ifr*0.5
dphi=twopi*delf*dt2
phi=0.0
do i=1,32
ctwk(i)=cmplx(cos(phi),sin(phi))
phi=mod(phi+dphi,twopi)
enddo
call sync8d(cd0,i0,ctwk,1,sync)
if( sync .gt. smax ) then
smax=sync
delfbest=delf
endif
enddo
a=0.0
a(1)=-delfbest
call twkfreq1(cd0,NP2,fs2,a,cd0)
xdt=xdt2
f1=f1+delfbest !Improved estimate of DF
call sync8d(cd0,i0,ctwk,2,sync)
j=0
do k=1,NN
i1=ibest+(k-1)*32
csymb=cmplx(0.0,0.0)
if( i1.ge.1 .and. i1+31 .le. NP2 ) csymb=cd0(i1:i1+31)
call four2a(csymb,32,1,-1,1)
s2(0:7,k)=abs(csymb(1:8))
enddo
j=0
do k=1,NN
if(k.le.7) cycle
if(k.ge.37 .and. k.le.43) cycle
if(k.gt.72) cycle
j=j+1
s1(0:7,j)=s2(0:7,k)
enddo
do j=1,ND
ps=s1(0:7,j)
where (ps.gt.0.0) ps=log(ps)
r1=max(ps(1),ps(3),ps(5),ps(7))-max(ps(0),ps(2),ps(4),ps(6))
r2=max(ps(2),ps(3),ps(6),ps(7))-max(ps(0),ps(1),ps(4),ps(5))
r4=max(ps(4),ps(5),ps(6),ps(7))-max(ps(0),ps(1),ps(2),ps(3))
i4=3*j-2
i2=3*j-1
i1=3*j
rxdata(i4)=r4
rxdata(i2)=r2
rxdata(i1)=r1
rxdatap(i4)=r4
rxdatap(i2)=r2
rxdatap(i1)=r1
! When bits 88:115 are set as ap bits, bit 115 lives in symbol 39 along
! with no-ap bits 116 and 117. Take care of metrics for bits 116 and 117.
! if(j.eq.39) then ! take care of bits that live in symbol 39
! if(apsym(28).lt.0) then
! rxdatap(i2)=max(ps(2),ps(3))-max(ps(0),ps(1))
! rxdatap(i1)=max(ps(1),ps(3))-max(ps(0),ps(2))
! else
! rxdatap(i2)=max(ps(6),ps(7))-max(ps(4),ps(5))
! rxdatap(i1)=max(ps(5),ps(7))-max(ps(4),ps(6))
! endif
! endif
! When bits 116:143 are set as ap bits, bit 115 lives in symbol 39 along
! with ap bits 116 and 117. Take care of metric for bit 115.
if(j.eq.39) then ! take care of bit 115
iii=2*(apsym(29)+1)/2 + (apsym(30)+1)/2 ! known values of bits 116 & 117
if(iii.eq.0) rxdatap(i4)=ps(4)-ps(0)
if(iii.eq.1) rxdatap(i4)=ps(5)-ps(1)
if(iii.eq.2) rxdatap(i4)=ps(6)-ps(2)
if(iii.eq.3) rxdatap(i4)=ps(7)-ps(3)
endif
! bit 144 lives in symbol 48 and will be 1 if it is set as an ap bit.
! take care of metrics for bits 142 and 143
if(j.eq.48) then ! bit 144 is always 1
rxdatap(i4)=max(ps(5),ps(7))-max(ps(1),ps(3))
rxdatap(i2)=max(ps(3),ps(7))-max(ps(1),ps(5))
endif
! bit 154 lives in symbol 52 and will be 0 if it is set as an ap bit
! take care of metrics for bits 155 and 156
if(j.eq.52) then ! bit 154 will be 0 if it is set as an ap bit.
rxdatap(i2)=max(ps(2),ps(3))-max(ps(0),ps(1))
rxdatap(i1)=max(ps(1),ps(3))-max(ps(0),ps(2))
endif
enddo
rxav=sum(rxdata)/(3.0*ND)
rx2av=sum(rxdata*rxdata)/(3.0*ND)
var=rx2av-rxav*rxav
if( var .gt. 0.0 ) then
rxsig=sqrt(var)
else
rxsig=sqrt(rx2av)
endif
rxdata=rxdata/rxsig
! Let's just assume that rxsig is OK for rxdatap too...
rxdatap=rxdatap/rxsig
ss=0.84
llr0=2.0*rxdata/(ss*ss)
llra=2.0*rxdatap/(ss*ss) ! llr's for use with ap
apmag=4.0
! If DxCall exists, only do "MyCall DxCall ???" for candidates within nfqso +/- napwid
nap=0
if(lapon.and.(ndepth.eq.3).and.(iaptype.eq.1 .or. (iaptype.eq.2.and.abs(nfqso-f1).le.napwid))) nap=2
if(lapon.and.(ndepth.eq.3).and.iaptype.eq.2.and.abs(nfqso-f1).gt.napwid) nap=1
do iap=0,nap !### Temporary ###
nera=1
if(iap.eq.0) nera=3
do iera=1,nera
llr=llr0
nblank=0
if(nera.eq.3 .and. iera.eq.1) nblank=0
if(nera.eq.3 .and. iera.eq.2) nblank=24
if(nera.eq.3 .and. iera.eq.3) nblank=48
if(nblank.gt.0) llr(1:nblank)=0.
if(iap.eq.0) then
apmask=0
! apmask(160:162)=1
llrap=llr
! llrap(160:162)=apmag*apsym(73:75)/ss
endif
if(iaptype.eq.1) then
if(iap.eq.1) then ! look for plain CQ
apmask=0
apmask(88:115)=1 ! plain CQ
apmask(144)=1 ! not free text
! apmask(160:162)=1 ! 3 extra bits
llrap=llr
llrap(88:115)=apmag*cq/ss
llrap(116:117)=llra(116:117)
llrap(142:143)=llra(142:143)
llrap(144)=-apmag/ss
! llrap(160:162)=apmag*apsym(73:75)/ss
endif
if(iap.eq.2) then ! look for mycall
apmask=0
apmask(88:115)=1 ! mycall
apmask(144)=1 ! not free text
! apmask(160:162)=1 ! 3 extra bits
llrap=llr
llrap(88:115)=apmag*apsym(1:28)/ss
llrap(116:117)=llra(116:117)
llrap(142:143)=llra(142:143)
llrap(144)=-apmag/ss
! llrap(160:162)=apmag*apsym(73:75)/ss
endif
endif
if(iaptype.eq.2) then
if(iap.eq.1) then ! look for dxcall
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=llr
! llrap(88:143)=apmag*apsym(1:56)/ss
llrap(115)=llra(115)
llrap(116:143)=apmag*apsym(29:56)/ss
llrap(144)=-apmag/ss
! llrap(160:162)=apmag*apsym(73:75)/ss
endif
if(iap.eq.2) then ! look mycall, dxcall
apmask=0
apmask(88:115)=1 ! mycall
apmask(116:143)=1 ! hiscall
apmask(144)=1 ! not free text
! apmask(144:154)=1 ! RRR or 73
! apmask(160:162)=1 ! 3 extra bits
llrap=llr
llrap(88:143)=apmag*apsym(1:56)/ss
llrap(144)=-apmag/ss
! llrap(144:154)=apmag*rr73/ss
! llrap(155:156)=llra(155:156)
! llrap(160:162)=apmag*apsym(73:75)/ss
endif
endif
cw=0
call timer('bpd174 ',0)
call bpdecode174(llrap,apmask,max_iterations,decoded,cw,nharderrors, &
niterations)
call timer('bpd174 ',1)
dmin=0.0
if(ndepth.eq.3 .and. nharderrors.lt.0) then
norder=1
if(abs(nfqso-f1).le.napwid) norder=2 !Decode using norder=2 within napwid of nfqso.
call timer('osd174 ',0)
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(any(decoded(75:75).ne.0)) cycle !Reject if any of the 3 extra bits are nonzero
if(nharderrors.ge.0 .and. nharderrors+dmin.lt.60.0 .and. &
.not.(sync.lt.2.0 .and. nharderrors.gt.35) .and. &
.not.(iap.gt.0 .and. nharderrors.gt.39) .and. &
.not.(iera.ge.2 .and. nharderrors.gt.30) &
) then
call chkcrc12a(decoded,nbadcrc)
else
nharderrors=-1
cycle
endif
if(nbadcrc.eq.0) then
call extractmessage174(decoded,message,ncrcflag,recent_calls,nrecent)
call genft8(message,msgsent,msgbits,itone)
if(lsubtract) call subtractft8(dd0,itone,f1,xdt2)
xsig=0.0
xnoi=0.0
do i=1,79
xsig=xsig+s2(itone(i),i)**2
ios=mod(itone(i)+4,7)
xnoi=xnoi+s2(ios,i)**2
enddo
xsnr=0.001
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
return
endif
enddo
enddo
return
end subroutine ft8b