WSJT-X/libm65/jtmsk.f90
Joe Taylor 5079669e49 Now have a properly functioning stand-along decoder for JTMSK.
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/jtms3@2529 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
2012-07-19 18:01:14 +00:00

73 lines
2.4 KiB
Fortran

subroutine jtmsk(dat,npts,cfile6,tpk,mswidth,ndb,nrpt,Nfreeze, &
ntol,MouseDF,pick,mycall)
! Decode a JTMSK ping
parameter (NZ=2*48000)
real dat(npts) !Raw data
complex cdat(NZ) !Analytic form of signal
character*6 cfile6 !FileID
logical pick
character*12 mycall
real s(NZ) !Power spectrum
real s2(0:63,400)
real r(60000)
complex cw(168,0:63) !Complex waveforms for all codewords
complex cwb(168) !Complex waveform for <space>
logical first
character msg*400,msg29*29
data first/.true./
save first,cw,cwb
save cdat !Fix its address, for four2
if(first) call setupmsk(cw,cwb) !Calculate waveforms for codewords
first=.false.
nsps=24 !Samples per symbol
f0=1000.0 !Nominal frequency for bit=0
n=log(float(npts))/log(2.0) + 1.0
nfft1=2**n !FFT length
call analytic(dat,npts,nfft1,s,cdat) !Convert to analytic signal
call mskdf(cdat,npts,tpk,nfft1,f0,nfreeze,mousedf,ntol, &
dfx,snrsq2) !Get DF
sq2lim=7.0
if(pick) sq2lim=5.0
if(snrsq2.lt.sq2lim) go to 900 !Reject non-JTMS signals
call tweak1(cdat,npts,-dfx,cdat) !Mix to standard frequency
call syncmsk(cdat,npts,cwb,r,i1) !Get character sync
call lenmsk(r,npts,msglen) !Find message length
s2=0.
nchar=(npts-168+1-i1)/168
if(nchar.gt.400) nchar=400
call decodemsk(cdat,npts,cw,i1,nchar,s2,msg) !Decode the message
ia=1
if(nchar.ge.40) ia=min(nchar/3,nchar-28)
ib=min(ia+28,nchar) !Can better limits ia, ib be found?
msg29=adjustl(msg(ia:ib))
msg=adjustl(msg)
ib=min(nchar,45)
ndf=nint(dfx)
nchk=max(20,nint(1.5*msglen))
if(msglen.eq.0 .or. nchar.lt.nchk .or. pick) then
write(*,1110) cfile6,tpk,mswidth,ndb,nrpt,ndf,msg(1:45)
1110 format(a6,f5.1,i5,i3,1x,i2.2,i5,5x,a45)
endif
if(msglen.gt.0 .and. nchar.ge.nchk) then
call foldmsk(s2,msglen,nchar,mycall,msg,msg29) !Decode folded message
write(*,1120) cfile6,tpk,mswidth,ndb,nrpt,ndf,msg29
1120 format(a6,f5.1,i5,i3,1x,i2.2,i5,5x,a29,11x,'*')
endif
900 continue
return
end subroutine jtmsk