WSJT-X/lib/ft4_decode.f90

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Fortran
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2019-04-02 12:21:03 -04:00
module ft4_decode
type :: ft4_decoder
procedure(ft4_decode_callback), pointer :: callback
contains
procedure :: decode
end type ft4_decoder
abstract interface
subroutine ft4_decode_callback (this,sync,snr,dt,freq,decoded,nap,qual)
import ft4_decoder
implicit none
class(ft4_decoder), intent(inout) :: this
real, intent(in) :: sync
integer, intent(in) :: snr
real, intent(in) :: dt
real, intent(in) :: freq
character(len=37), intent(in) :: decoded
integer, intent(in) :: nap
real, intent(in) :: qual
end subroutine ft4_decode_callback
end interface
contains
subroutine decode(this,callback,iwave,nQSOProgress,nfqso, &
nutc,nfa,nfb,ndepth,ncontest,mycall,hiscall)
use timer_module, only: timer
use packjt77
include 'ft4/ft4_params.f90'
class(ft4_decoder), intent(inout) :: this
procedure(ft4_decode_callback) :: callback
parameter (NSS=NSPS/NDOWN)
parameter (NZZ=18*3456)
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character message*37,msgsent*37,msg0*37
character c77*77
character*37 decodes(100)
character*512 data_dir,fname
character*17 cdatetime0
character*12 mycall,hiscall
character*12 mycall0,hiscall0
character*6 hhmmss
character*4 cqstr,cqstr0
complex cd2(0:NZZ/NDOWN-1) !Complex waveform
complex cb(0:NZZ/NDOWN-1+NN*NSS)
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complex cd(0:NN*NSS-1) !Complex waveform
complex ctwk(2*NSS),ctwk2(2*NSS,-16:16)
complex csymb(NSS)
complex cs(0:3,NN)
real s4(0:3,NN)
real bmeta(2*NN),bmetb(2*NN),bmetc(2*NN)
real a(5)
real llr(2*ND),llra(2*ND),llrb(2*ND),llrc(2*ND),llrd(2*ND)
real s2(0:255)
real candidate(3,100)
real savg(NH1),sbase(NH1)
integer apbits(2*ND)
integer apmy_ru(28),aphis_fd(28)
integer icos4a(0:3),icos4b(0:3),icos4c(0:3),icos4d(0:3)
integer*2 iwave(NZZ) !Raw received data
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integer*1 message77(77),rvec(77),apmask(2*ND),cw(2*ND)
integer*1 hbits(2*NN)
integer graymap(0:3)
integer ip(1)
integer nappasses(0:5) ! # of decoding passes for QSO States 0-5
integer naptypes(0:5,4) ! nQSOProgress, decoding pass
integer mcq(29)
integer mrrr(19),m73(19),mrr73(19)
logical nohiscall,unpk77_success
logical one(0:255,0:7) ! 256 4-symbol sequences, 8 bits
logical first, dobigfft
data icos4a/0,1,3,2/
data icos4b/1,0,2,3/
data icos4c/2,3,1,0/
data icos4d/3,2,0,1/
data graymap/0,1,3,2/
data msg0/' '/
data first/.true./
data mcq/0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0/
data mrrr/0,1,1,1,1,1,1,0,1,0,0,1,0,0,1,0,0,0,1/
data m73/0,1,1,1,1,1,1,0,1,0,0,1,0,1,0,0,0,0,1/
data mrr73/0,1,1,1,1,1,1,0,0,1,1,1,0,1,0,1,0,0,1/
data rvec/0,1,0,0,1,0,1,0,0,1,0,1,1,1,1,0,1,0,0,0,1,0,0,1,1,0,1,1,0, &
1,0,0,1,0,1,1,0,0,0,0,1,0,0,0,1,0,1,0,0,1,1,1,1,0,0,1,0,1, &
0,1,0,1,0,1,1,0,1,1,1,1,1,0,0,0,1,0,1/
save fs,dt,tt,txt,twopi,h,one,first,apbits,nappasses,naptypes, &
mycall0,hiscall0,msg0,cqstr0,ctwk2
this%callback => callback
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hhmmss=cdatetime0(8:13)
if(first) then
fs=12000.0/NDOWN !Sample rate after downsampling
dt=1/fs !Sample interval after downsample (s)
tt=NSPS*dt !Duration of "itone" symbols (s)
txt=NZ*dt !Transmission length (s) without ramp up/down
twopi=8.0*atan(1.0)
h=1.0
one=.false.
do i=0,255
do j=0,7
if(iand(i,2**j).ne.0) one(i,j)=.true.
enddo
enddo
do idf=-16,16
a=0.
a(1)=real(idf)
ctwk=1.
call twkfreq1(ctwk,2*NSS,fs/2.0,a,ctwk2(:,idf))
enddo
mrrr=2*mod(mrrr+rvec(59:77),2)-1
m73=2*mod(m73+rvec(59:77),2)-1
mrr73=2*mod(mrr73+rvec(59:77),2)-1
nappasses(0)=2
nappasses(1)=2
nappasses(2)=2
nappasses(3)=2
nappasses(4)=2
nappasses(5)=3
! iaptype
!------------------------
! 1 CQ ??? ??? (29 ap bits)
! 2 MyCall ??? ??? (29 ap bits)
! 3 MyCall DxCall ??? (58 ap bits)
! 4 MyCall DxCall RRR (77 ap bits)
! 5 MyCall DxCall 73 (77 ap bits)
! 6 MyCall DxCall RR73 (77 ap bits)
!********
naptypes(0,1:4)=(/1,2,0,0/) ! Tx6 selected (CQ)
naptypes(1,1:4)=(/2,3,0,0/) ! Tx1
naptypes(2,1:4)=(/2,3,0,0/) ! Tx2
naptypes(3,1:4)=(/3,6,0,0/) ! Tx3
naptypes(4,1:4)=(/3,6,0,0/) ! Tx4
naptypes(5,1:4)=(/3,1,2,0/) ! Tx5
mycall0=''
hiscall0=''
cqstr0=''
first=.false.
endif
if(cqstr.ne.cqstr0) then
i0=index(cqstr,' ')
if(i0.le.1) then
message='CQ A1AA AA01'
else
message='CQ '//cqstr(1:i0-1)//' A1AA AA01'
endif
i3=-1
n3=-1
call pack77(message,i3,n3,c77)
call unpack77(c77,1,msgsent,unpk77_success)
read(c77,'(29i1)') mcq
mcq=2*mod(mcq+rvec(1:29),2)-1
cqstr0=cqstr
endif
l1=index(mycall,char(0))
if(l1.ne.0) mycall(l1:)=" "
l1=index(hiscall,char(0))
if(l1.ne.0) hiscall(l1:)=" "
if(mycall.ne.mycall0 .or. hiscall.ne.hiscall0) then
apbits=0
apbits(1)=99
apbits(30)=99
apmy_ru=0
aphis_fd=0
if(len(trim(mycall)) .lt. 3) go to 10
nohiscall=.false.
hiscall0=hiscall
if(len(trim(hiscall0)).lt.3) then
hiscall0=mycall ! use mycall for dummy hiscall - mycall won't be hashed.
nohiscall=.true.
endif
message=trim(mycall)//' '//trim(hiscall0)//' RR73'
i3=-1
n3=-1
call pack77(message,i3,n3,c77)
call unpack77(c77,1,msgsent,unpk77_success)
if(i3.ne.1 .or. (message.ne.msgsent) .or. .not.unpk77_success) go to 10
read(c77,'(77i1)') message77
apmy_ru=2*mod(message77(1:28)+rvec(2:29),2)-1
aphis_fd=2*mod(message77(30:57)+rvec(29:56),2)-1
message77=mod(message77+rvec,2)
call encode174_91(message77,cw)
apbits=2*cw-1
if(nohiscall) apbits(30)=99
10 continue
mycall0=mycall
hiscall0=hiscall
endif
candidate=0.0
ncand=0
syncmin=1.2
maxcand=100
fa=nfa
fb=nfb
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call timer('getcand4',0)
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call getcandidates4(iwave,fa,fb,syncmin,nfqso,maxcand,savg,candidate, &
ncand,sbase)
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call timer('getcand4',1)
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ndecodes=0
dobigfft=.true.
do icand=1,ncand
f0=candidate(1,icand)
snr=candidate(3,icand)-1.0
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call timer('ft4_down',0)
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call ft4_downsample(iwave,dobigfft,f0,cd2) !Downsample to 32 Sam/Sym
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call timer('ft4_down',1)
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if(dobigfft) dobigfft=.false.
sum2=sum(cd2*conjg(cd2))/(real(NZZ)/real(NDOWN))
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if(sum2.gt.0.0) cd2=cd2/sqrt(sum2)
! Sample rate is now 12000/16 = 750 samples/second
do isync=1,2
if(isync.eq.1) then
idfmin=-12
idfmax=12
idfstp=3
ibmin=0
ibmax=800
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ibstp=4
else
idfmin=idfbest-4
idfmax=idfbest+4
idfstp=1
ibmin=max(0,ibest-5)
ibmax=min(ibest+5,NZZ/NDOWN-1)
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ibstp=1
endif
ibest=-1
smax=-99.
idfbest=0
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call timer('sync4d ',0)
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do idf=idfmin,idfmax,idfstp
do istart=ibmin,ibmax,ibstp
call sync4d(cd2,istart,ctwk2(:,idf),1,sync) !Find sync power
if(sync.gt.smax) then
smax=sync
ibest=istart
idfbest=idf
endif
enddo
enddo
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call timer('sync4d ',1)
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enddo
f0=f0+real(idfbest)
if( f0.le.10.0 .or. f0.ge.4990.0 ) cycle
! write(*,3002) smax,ibest/750.0,f0
!3002 format('b',3f8.2)
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call timer('ft4down ',0)
call ft4_downsample(iwave,dobigfft,f0,cb) !Final downsample, corrected f0
call timer('ft4down ',1)
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sum2=sum(abs(cb)**2)/(real(NSS)*NN)
if(sum2.gt.0.0) cb=cb/sqrt(sum2)
cd=cb(ibest:ibest+NN*NSS-1)
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call timer('four2a ',0)
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do k=1,NN
i1=(k-1)*NSS
csymb=cd(i1:i1+NSS-1)
call four2a(csymb,NSS,1,-1,1)
cs(0:3,k)=csymb(1:4)
s4(0:3,k)=abs(csymb(1:4))
enddo
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call timer('four2a ',1)
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! Sync quality check
is1=0
is2=0
is3=0
is4=0
do k=1,4
ip=maxloc(s4(:,k))
if(icos4a(k-1).eq.(ip(1)-1)) is1=is1+1
ip=maxloc(s4(:,k+33))
if(icos4b(k-1).eq.(ip(1)-1)) is2=is2+1
ip=maxloc(s4(:,k+66))
if(icos4c(k-1).eq.(ip(1)-1)) is3=is3+1
ip=maxloc(s4(:,k+99))
if(icos4d(k-1).eq.(ip(1)-1)) is4=is4+1
enddo
nsync=is1+is2+is3+is4 !Number of correct hard sync symbols, 0-16
if(smax .lt. 0.7 .or. nsync .lt. 8) cycle
do nseq=1,3 !Try coherent sequences of 1, 2, and 4 symbols
if(nseq.eq.1) nsym=1
if(nseq.eq.2) nsym=2
if(nseq.eq.3) nsym=4
nt=2**(2*nsym)
do ks=1,NN-nsym+1,nsym !87+16=103 symbols.
amax=-1.0
do i=0,nt-1
i1=i/64
i2=iand(i,63)/16
i3=iand(i,15)/4
i4=iand(i,3)
if(nsym.eq.1) then
s2(i)=abs(cs(graymap(i4),ks))
elseif(nsym.eq.2) then
s2(i)=abs(cs(graymap(i3),ks)+cs(graymap(i4),ks+1))
elseif(nsym.eq.4) then
s2(i)=abs(cs(graymap(i1),ks ) + &
cs(graymap(i2),ks+1) + &
cs(graymap(i3),ks+2) + &
cs(graymap(i4),ks+3) &
)
else
print*,"Error - nsym must be 1, 2, or 4."
endif
enddo
ipt=1+(ks-1)*2
if(nsym.eq.1) ibmax=1
if(nsym.eq.2) ibmax=3
if(nsym.eq.4) ibmax=7
do ib=0,ibmax
bm=maxval(s2(0:nt-1),one(0:nt-1,ibmax-ib)) - &
maxval(s2(0:nt-1),.not.one(0:nt-1,ibmax-ib))
if(ipt+ib.gt.2*NN) cycle
if(nsym.eq.1) then
bmeta(ipt+ib)=bm
elseif(nsym.eq.2) then
bmetb(ipt+ib)=bm
elseif(nsym.eq.4) then
bmetc(ipt+ib)=bm
endif
enddo
enddo
enddo
bmetb(205:206)=bmeta(205:206)
bmetc(201:204)=bmetb(201:204)
bmetc(205:206)=bmeta(205:206)
call normalizebmet(bmeta,2*NN)
call normalizebmet(bmetb,2*NN)
call normalizebmet(bmetc,2*NN)
hbits=0
where(bmeta.ge.0) hbits=1
ns1=count(hbits( 1: 8).eq.(/0,0,0,1,1,0,1,1/))
ns2=count(hbits( 67: 74).eq.(/0,1,0,0,1,1,1,0/))
ns3=count(hbits(133:140).eq.(/1,1,1,0,0,1,0,0/))
ns4=count(hbits(199:206).eq.(/1,0,1,1,0,0,0,1/))
nsync_qual=ns1+ns2+ns3+ns4
if(nsync_qual.lt. 20) cycle
scalefac=2.83
llra( 1: 58)=bmeta( 9: 66)
llra( 59:116)=bmeta( 75:132)
llra(117:174)=bmeta(141:198)
llra=scalefac*llra
llrb( 1: 58)=bmetb( 9: 66)
llrb( 59:116)=bmetb( 75:132)
llrb(117:174)=bmetb(141:198)
llrb=scalefac*llrb
llrc( 1: 58)=bmetc( 9: 66)
llrc( 59:116)=bmetc( 75:132)
llrc(117:174)=bmetc(141:198)
llrc=scalefac*llrc
apmag=maxval(abs(llra))*1.1
npasses=3+nappasses(nQSOProgress)
if(ncontest.ge.5) npasses=3 ! Don't support Fox and Hound
do ipass=1,npasses
if(ipass.eq.1) llr=llra
if(ipass.eq.2) llr=llrb
if(ipass.eq.3) llr=llrc
if(ipass.le.3) then
apmask=0
iaptype=0
endif
if(ipass .gt. 3) then
llrd=llrc
iaptype=naptypes(nQSOProgress,ipass-3)
! ncontest=0 : NONE
! 1 : NA_VHF
! 2 : EU_VHF
! 3 : FIELD DAY
! 4 : RTTY
! 5 : FOX
! 6 : HOUND
!
! Conditions that cause us to bail out of AP decoding
napwid=50
if(ncontest.le.4 .and. iaptype.ge.3 .and. (abs(f0-nfqso).gt.napwid) ) cycle
if(iaptype.ge.2 .and. apbits(1).gt.1) cycle ! No, or nonstandard, mycall
if(iaptype.ge.3 .and. apbits(30).gt.1) cycle ! No, or nonstandard, dxcall
if(iaptype.eq.1) then ! CQ or CQ TEST or CQ FD or CQ RU or CQ SCC
apmask=0
apmask(1:29)=1
llrd(1:29)=apmag*mcq(1:29)
endif
if(iaptype.eq.2) then ! MyCall,???,???
apmask=0
if(ncontest.eq.0.or.ncontest.eq.1) then
apmask(1:29)=1
llrd(1:29)=apmag*apbits(1:29)
else if(ncontest.eq.2) then
apmask(1:28)=1
llrd(1:28)=apmag*apbits(1:28)
else if(ncontest.eq.3) then
apmask(1:28)=1
llrd(1:28)=apmag*apbits(1:28)
else if(ncontest.eq.4) then
apmask(2:29)=1
llrd(2:29)=apmag*apmy_ru(1:28)
endif
endif
if(iaptype.eq.3) then ! MyCall,DxCall,???
apmask=0
if(ncontest.eq.0.or.ncontest.eq.1.or.ncontest.eq.2) then
apmask(1:58)=1
llrd(1:58)=apmag*apbits(1:58)
else if(ncontest.eq.3) then ! Field Day
apmask(1:56)=1
llrd(1:28)=apmag*apbits(1:28)
llrd(29:56)=apmag*aphis_fd(1:28)
else if(ncontest.eq.4) then ! RTTY RU
apmask(2:57)=1
llrd(2:29)=apmag*apmy_ru(1:28)
llrd(30:57)=apmag*apbits(30:57)
endif
endif
if(iaptype.eq.4 .or. iaptype.eq.5 .or. iaptype.eq.6) then
apmask=0
if(ncontest.le.4) then
apmask(1:91)=1 ! mycall, hiscall, RRR|73|RR73
if(iaptype.eq.6) llrd(1:91)=apmag*apbits(1:91)
endif
endif
llr=llrd
endif
max_iterations=40
message77=0
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call timer('bpdec174',0)
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call bpdecode174_91(llr,apmask,max_iterations,message77, &
cw,nharderror,niterations)
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call timer('bpdec174',1)
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if(sum(message77).eq.0) cycle
if( nharderror.ge.0 ) then
message77=mod(message77+rvec,2) ! remove rvec scrambling
write(c77,'(77i1)') message77(1:77)
call unpack77(c77,1,message,unpk77_success)
idupe=0
do i=1,ndecodes
if(decodes(i).eq.message) idupe=1
enddo
if(ibest.le.10 .and. message.eq.msg0) idupe=1 !Already decoded
if(idupe.eq.1) exit
ndecodes=ndecodes+1
decodes(ndecodes)=message
if(snr.gt.0.0) then
xsnr=10*log10(snr)-14.0
else
xsnr=-20.0
endif
nsnr=nint(max(-20.0,xsnr))
xdt=ibest/750.0 - 0.5
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call this%callback(sync,nsnr,xdt,f0,message,iaptype,qual)
if(ibest.ge.ibmax-15) msg0=message !Possible dupe candidate
exit
endif
enddo !Sequence estimation
enddo !Candidate list
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return
end subroutine decode
end module ft4_decode