WSJT-X/lib/softsym.f90
Joe Taylor 79538977c7 Further improvements to JT9 decoder.
Better AFC (wider range of possible drifts; more accurate DT alignment).
Better definition of metric tables used by Fano decoder.
Zero-centeres soft symbols, instead of offset +128.
Tuned several empirical parameters.


git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@5004 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
2015-03-04 17:07:15 +00:00

49 lines
1.3 KiB
Fortran

subroutine softsym(id2,npts8,nsps8,newdat,fpk,syncpk,snrdb,xdt, &
freq,drift,a3,schk,i1SoftSymbols)
! Compute the soft symbols
complex c2(0:1440-1)
complex c3(0:1440-1)
complex c5(0:1440-1)
real a(3)
integer*1 i1SoftSymbolsScrambled(207)
integer*1 i1SoftSymbols(207)
include 'jt9sync.f90'
nspsd=16
ndown=nsps8/nspsd
! Mix, low-pass filter, and downsample to 16 samples per symbol
call timer('downsam9',0)
call downsam9(id2,npts8,nsps8,newdat,nspsd,fpk,c2,nz2)
call timer('downsam9',1)
call peakdt9(c2,nz2,nsps8,nspsd,c3,nz3,xdt) !Find DT
fsample=1500.0/ndown
a=0.
call timer('afc9 ',0)
call afc9(c3,nz3,fsample,a,syncpk) !Find deltaF, fDot, fDDot
call timer('afc9 ',1)
freq=fpk - a(1)
drift=-2.0*a(2)
a3=a(3)
a(3)=0.
call timer('twkfreq ',0)
call twkfreq(c3,c5,nz3,fsample,a) !Correct for delta f, f1, f2 ==> a(1:3)
call timer('twkfreq ',1)
! Compute soft symbols (in scrambled order)
call timer('symspec2',0)
call symspec2(c5,nz3,nsps8,nspsd,fsample,freq,drift,snrdb,schk, &
i1SoftSymbolsScrambled)
call timer('symspec2',1)
! Remove interleaving
call interleave9(i1SoftSymbolsScrambled,-1,i1SoftSymbols)
return
end subroutine softsym