WSJT-X/lib/jtmsk_decode.f90
Joe Taylor be26c48f91 More progress on decoder for short JTMSK messages.
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@6462 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
2016-02-03 19:47:42 +00:00

116 lines
3.6 KiB
Fortran

subroutine jtmsk_decode(id2,narg,line)
! Decoder for JTMSK mode
parameter (NMAX=30*12000)
parameter (NFFTMAX=512*1024)
parameter (NSPM=1404) !Samples per JTMSK long message
integer*2 id2(0:NMAX) !Raw i*2 data, up to T/R = 30 s
real d(0:NMAX) !Raw r*4 data
real ty(NMAX/512) !Ping times
real yellow(NMAX/512)
complex c(NFFTMAX) !Complex (analytic) data
complex cdat(24000) !Short segments, up to 2 s
complex cdat2(24000)
integer narg(0:13) !Arguments passed from calling pgm
character*22 msg,msg0 !Decoded message
character*80 line(100) !Decodes passed back to caller
! Parameters from GUI are in narg():
nutc=narg(0) !UTC
npts=min(narg(1),NMAX) !Number of samples in id2 (12000 Hz)
newdat=narg(3) !1==> new data, compute symbol spectra
minsync=narg(4) !Lower sync limit
npick=narg(5)
t0=0.001*narg(6)
t1=0.001*narg(7)
maxlines=narg(8) !Max # of decodes to return to caller
nmode=narg(9)
nrxfreq=narg(10) !Target Rx audio frequency (Hz)
ntol=narg(11) !Search range, +/- ntol (Hz)
nhashcalls=narg(12)
nsnr0=-99
nline=0
line(1:100)(1:1)=char(0)
msg0=' '
msg=msg0
d(0:npts-1)=id2(0:npts-1)
rms=sqrt(dot_product(d(0:npts-1),d(0:npts-1))/npts)
!### Would it be better to set median rms to 1.0 ?
d(0:npts-1)=d(0:npts-1)/rms !Normalize so that rms=1.0
call mskdt(d,npts,ty,yellow,nyel)
nyel=min(nyel,5)
n=log(float(npts))/log(2.0) + 1.0
nfft=min(2**n,1024*1024)
call analytic(d,npts,nfft,c) !Convert to analytic signal and filter
nbefore=NSPM
nafter=4*NSPM
! Process ping list (sorted by S/N) from top down.
do n=1,nyel
ia=ty(n)*12000.0 - nbefore
if(ia.lt.1) ia=1
ib=ia + nafter
if(ib.gt.NFFTMAX) ib=NFFTMAX
iz=ib-ia+1
cdat2(1:iz)=c(ia:ib) !Select nlen complex samples
ja=ia/NSPM + 1
jb=ib/NSPM
t0=ia/12000.0
do itry=1,21
idf1=(itry/2) * 50
if(mod(itry,2).eq.1) idf1=-idf1
if(abs(idf1).gt.ntol) exit
fpk=idf1 + nrxfreq
call tweak1(cdat2,iz,1500.0-fpk,cdat)
call syncmsk(cdat,iz,jpk,ipk,idf,rmax,snr,metric,msg)
freq=fpk+idf
if(metric.eq.-9999) cycle !No output if no significant sync
t0=(ia+jpk)/12000.0
nsnr=nint(yellow(n)-2.0)
if(msg.eq.' ') then
call jtmsk_short(cdat,iz,narg,tbest,idfpk,msg)
endif
if(msg.ne.' ') then
if(msg.ne.msg0) then
nline=nline+1
nsnr0=-99
endif
if(nsnr.gt.nsnr0 .and. nline.gt.0) then
call rectify_msk(cdat2(jpk:jpk+NSPM-1),msg,freq2)
write(line(nline),1020) nutc,nsnr,t0,nint(freq2),msg
1020 format(i6.6,i4,f5.1,i5,' & ',a22)
nsnr0=nsnr
go to 900
endif
msg0=msg
if(nline.ge.maxlines) go to 900
endif
enddo
enddo
900 continue
nline=1
if(nline.eq.0) then
msg=' '
call jtmsk_short(c,npts,narg,tbest,idfpk,msg)
!### Needs work!
if(msg.ne.' ') then
nline=nline+1
j=nint(12000.0*tbest/512.0)
nsnr=nint(3*(yellow(j)-2.0))
write(line(nline),1020) nutc,nsnr,tbest,nrxfreq+idfpk,msg
endif
!###
endif
if(line(1)(1:6).eq.' ') line(1)(1:1)=char(0)
return
end subroutine jtmsk_decode