WSJT-X/lib/fsk4hf/ft4d.f90

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9.5 KiB
Fortran
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program ft4d
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use crc
use packjt77
include 'ft4_params.f90'
character arg*8,message*37,c77*77,infile*80,fname*16,datetime*11
character*37 decodes(100)
character*120 data_dir
character*90 dmsg
complex cd2(0:NMAX/16-1) !Complex waveform
complex cb(0:NMAX/16-1)
complex cd(0:76*20-1) !Complex waveform
complex csum,cterm
complex ctwk(80),ctwk2(80)
complex csymb(20)
complex cs(0:3,NN)
real s4(0:3,NN)
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real*8 fMHz
real ps(0:8191),psbest(0:8191)
real bmeta(152),bmetb(152),bmetc(152)
real s(NH1,NHSYM)
real a(5)
real llr(128),llr2(128),llra(128),llrb(128),llrc(128)
real s2(0:255)
real candidate(3,100)
real savg(NH1),sbase(NH1)
integer ihdr(11)
integer icos4(0:3)
integer*2 iwave(NMAX) !Generated full-length waveform
integer*1 message77(77),apmask(128),cw(128)
integer*1 hbits(152),hbits1(152),hbits3(152)
integer*1 s12(12)
integer graymap(0:3)
integer ip(1)
logical unpk77_success
logical one(0:511,0:7) ! 256 4-symbol sequences, 8 bits
data s12/1,1,1,2,2,2,2,2,2,1,1,1/
data icos4/0,1,3,2/
data graymap/0,1,3,2/
save one
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fs=12000.0/NDOWN !Sample rate
dt=1/fs !Sample interval after downsample (s)
tt=NSPS*dt !Duration of "itone" symbols (s)
baud=1.0/tt !Keying rate for "itone" symbols (baud)
txt=NZ*dt !Transmission length (s)
twopi=8.0*atan(1.0)
h=1.0 !h=0.8 seems to be optimum for AWGN sensitivity (not for fading)
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one=.false.
do i=0,255
do j=0,7
if(iand(i,2**j).ne.0) one(i,j)=.true.
enddo
enddo
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nargs=iargc()
if(nargs.lt.1) then
print*,'Usage: ft4d [-a <data_dir>] [-f fMHz] file1 [file2 ...]'
go to 999
endif
iarg=1
data_dir="."
call getarg(iarg,arg)
if(arg(1:2).eq.'-a') then
call getarg(iarg+1,data_dir)
iarg=iarg+2
endif
call getarg(iarg,arg)
if(arg(1:2).eq.'-f') then
call getarg(iarg+1,arg)
read(arg,*) fMHz
iarg=iarg+2
endif
ncoh=1
do ifile=iarg,nargs
call getarg(ifile,infile)
j2=index(infile,'.wav')
open(10,file=infile,status='old',access='stream')
read(10,end=999) ihdr,iwave
read(infile(j2-4:j2-1),*) nutc
datetime=infile(j2-11:j2-1)
close(10)
candidate=0.0
ncand=0
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nfqso=1500
nfa=500
nfb=2700
syncmin=1.0
maxcand=100
! call syncft4(iwave,nfa,nfb,syncmin,nfqso,maxcand,s,candidate,ncand,sbase)
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call getcandidates4(iwave,375.0,3000.0,0.2,2200.0,100,savg,candidate,ncand,sbase)
ndecodes=0
do icand=1,ncand
f0=candidate(1,icand)-1.5*37.5
xsnr=1.0
if( f0.le.375.0 .or. f0.ge.(5000.0-375.0) ) cycle
call ft4_downsample(iwave,f0,cd2) ! downsample from 320 Sa/Symbol to 20 Sa/Symbol
sum2=sum(cd2*conjg(cd2))/(20.0*76)
if(sum2.gt.0.0) cd2=cd2/sqrt(sum2)
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! 750 samples/second here
ibest=-1
smax=-99.
dfbest=-1.
do idf=-90,+90,5
df=idf
a=0.
a(1)=df
ctwk=1.
call twkfreq1(ctwk,80,fs,a,ctwk2)
do istart=0,315
call sync4d(cd2,istart,ctwk2,1,sync)
if(sync.gt.smax) then
smax=sync
ibest=istart
dfbest=df
endif
enddo
enddo
f0=f0+dfbest
!f0=1443.75
call ft4_downsample(iwave,f0,cb) ! downsample from 320s/Symbol to 20s/Symbol
sum2=sum(abs(cb)**2)/(20.0*76)
if(sum2.gt.0.0) cb=cb/sqrt(sum2)
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!ibest=208
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cd=cb(ibest:ibest+76*20-1)
do k=1,NN
i1=(k-1)*20
csymb=cd(i1:i1+19)
call four2a(csymb,20,1,-1,1)
cs(0:3,k)=csymb(1:4)/1e2
s4(0:3,k)=abs(csymb(1:4))
enddo
! sync quality check
is1=0
is2=0
is3=0
do k=1,4
ip=maxloc(s4(:,k))
if(icos4(k-1).eq.(ip(1)-1)) is1=is1+1
ip=maxloc(s4(:,k+36))
if(icos4(k-1).eq.(ip(1)-1)) is2=is2+1
ip=maxloc(s4(:,k+72))
if(icos4(k-1).eq.(ip(1)-1)) is3=is3+1
enddo
! hard sync sum - max is 12
nsync=is1+is2+is3
do nseq=1,3
if(nseq.eq.1) nsym=1
if(nseq.eq.2) nsym=2
if(nseq.eq.3) nsym=4
nt=2**(2*nsym)
do ks=1,76,nsym
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.152) 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
call normalizebmet(bmeta,152)
call normalizebmet(bmetb,152)
call normalizebmet(bmetc,152)
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( 73: 80).eq.(/0,0,0,1,1,0,1,1/))
ns3=count(hbits(145:152).eq.(/0,0,0,1,1,0,1,1/))
nsync_qual=ns1+ns2+ns3
sigma=0.7
llra(1:64)=bmeta(9:72)
llra(65:128)=bmeta(81:144)
llra=2*llra/sigma**2
llrb(1:64)=bmetb(9:72)
llrb(65:128)=bmetb(81:144)
llrb=2*llrb/sigma**2
llrc(1:64)=bmetc(9:72)
llrc(65:128)=bmetc(81:144)
llrc=2*llrc/sigma**2
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do isd=1,3
if(isd.eq.1) llr=llra
if(isd.eq.2) llr=llrb
if(isd.eq.3) llr=llrc
apmask=0
max_iterations=40
do ibias=0,0
llr2=llr
if(ibias.eq.1) llr2=llr+0.4
if(ibias.eq.2) llr2=llr-0.4
call bpdecode128_90(llr2,apmask,max_iterations,message77,cw,nharderror,niterations)
if(nharderror.ge.0) exit
enddo
if(sum(message77).eq.0) cycle
if( nharderror.ge.0 ) then
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(idupe.eq.1) cycle
ndecodes=ndecodes+1
decodes(ndecodes)=message
nsnr=nint(xsnr)
write(*,1212) datetime(8:11),nsnr,ibest/750.0,f0,message,'*',nharderror,nsync_qual,isd,niterations
1212 format(a4,i4,2x,f5.3,f11.1,2x,a22,a1,i5,i5,i5,i5)
endif
enddo ! sequence estimation
enddo !candidate list
enddo !files
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write(*,1120)
1120 format("<DecodeFinished>")
999 end program ft4d
subroutine getbitmetric(ib,ps,ns,xmet)
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real ps(0:ns-1)
xm1=0
xm0=0
do i=0,ns-1
if( iand(i/ib,1) .eq. 1 .and. ps(i) .gt. xm1 ) xm1=ps(i)
if( iand(i/ib,1) .eq. 0 .and. ps(i) .gt. xm0 ) xm0=ps(i)
enddo
xmet=xm1-xm0
return
end subroutine getbitmetric
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subroutine downsample4(ci,f0,co)
parameter(NI=144*160,NH=NI/2,NO=NI/16) ! downsample from 200 samples per symbol to 10
complex ci(0:NI-1),ct(0:NI-1)
complex co(0:NO-1)
fs=12000.0
df=fs/NI
ct=ci
call four2a(ct,NI,1,-1,1) !c2c FFT to freq domain
i0=nint(f0/df)
ct=cshift(ct,i0)
co=0.0
co(0)=ct(0)
b=8.0
do i=1,NO/2
arg=(i*df/b)**2
filt=exp(-arg)
co(i)=ct(i)*filt
co(NO-i)=ct(NI-i)*filt
enddo
co=co/NO
call four2a(co,NO,1,1,1) !c2c FFT back to time domain
return
end subroutine downsample4
subroutine ft4_downsample(iwave,f0,c)
! Input: i*2 data in iwave() at sample rate 12000 Hz
! Output: Complex data in c(), sampled at 1200 Hz
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include 'ft4_params.f90'
parameter (NFFT2=NMAX/16)
integer*2 iwave(NMAX)
complex c(0:NMAX/16-1)
complex c1(0:NFFT2-1)
complex cx(0:NMAX/2)
real x(NMAX)
equivalence (x,cx)
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BW=6.0*75
df=12000.0/NMAX
x=iwave
call four2a(x,NMAX,1,-1,0) !r2c FFT to freq domain
ibw=nint(BW/df)
i0=nint(f0/df)
c1=0.
c1(0)=cx(i0)
do i=1,NFFT2/2
arg=(i-1)*df/bw
win=exp(-arg*arg)
c1(i)=cx(i0+i)*win
c1(NFFT2-i)=cx(i0-i)*win
enddo
c1=c1/NFFT2
call four2a(c1,NFFT2,1,1,1) !c2c FFT back to time domain
c=c1(0:NMAX/16-1)
return
end subroutine ft4_downsample