WSJT-X/lib/mskrtd.f90
Steven Franke f210e47cd5 MSK144:
1. Clean up mskrtd to remove unused variables.
2. Re-instate Rx frequency spinbox in MSK144 mode to allow decoding of off-frequency signals with small FTol. Make changes needed to pass Rx Freq in to fortran routines. 
3. Enable realtime decoder for testing. Auto sequence does not yet work when realtime decoding is enabled. There are probably other bugs as well.




git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@7109 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
2016-09-25 00:16:29 +00:00

160 lines
4.6 KiB
Fortran

subroutine mskrtd(id2,nutc0,tsec,ntol,nrxfreq,line)
! Real-time decoder for MSK144.
! Analysis block size = NZ = 7168 samples, t_block = 0.597333 s
! Called from hspec() at half-block increments, about 0.3 s
parameter (NZ=7168) !Block size
parameter (NSPM=864) !Number of samples per message frame
parameter (NFFT1=8192) !FFT size for making analytic signal
parameter (NPATTERNS=4) !Number of frame averaging patterns to try
character*3 decsym !"&" for mskspd or "^" for long averages
character*22 msgreceived !Decoded message
character*22 msglast !!! temporary - used for dupechecking
character*80 line !Formatted line with UTC dB T Freq Msg
complex cdat(NFFT1) !Analytic signal
complex c(NSPM) !Coherently averaged complex data
complex ct(NSPM)
integer*2 id2(NZ) !Raw 16-bit data
integer iavmask(8)
integer iavpatterns(8,NPATTERNS)
integer npkloc(10)
integer nav(6)
real d(NFFT1)
real pow(8)
real xmc(NPATTERNS)
logical first
data first/.true./
data nav/1,2,3,5,7,9/
data iavpatterns/ &
1,1,1,1,0,0,0,0, &
0,0,1,1,1,1,0,0, &
1,1,1,1,1,0,0,0, &
1,1,1,1,1,1,1,0/
data xmc/2.0,4.5,2.5,3.5/ !Used to label decode with time at center of averaging mask
save first,t03,t12,nutc00,pnoise,nsnrlast,msglast
if(first) then
t03=0.0
t12=0.0
nutc00=nutc0
pnoise=-1.0
first=.false.
endif
fc=nrxfreq
!!! Dupe checking should probaby be moved to mainwindow.cpp
if( nutc00 .ne. nutc0 ) then ! reset dupe checker
msglast=' '
nsnrlast=-99
nutc00=nutc0
endif
tframe=float(NSPM)/12000.0
line=char(0)
msgreceived=' '
max_iterations=10
niterations=0
d(1:NZ)=id2
rms=sqrt(sum(d(1:NZ)*d(1:NZ))/NZ)
if(rms.lt.1.0) return
fac=1.0/rms
d(1:NZ)=fac*d(1:NZ)
d(NZ+1:NFFT1)=0.
call analytic(d,NZ,NFFT1,cdat) !Convert to analytic signal and filter
! Calculate average power for each frame and for the entire block.
! If decode is successful, largest power will be taken as signal+noise.
! If no decode, entire-block average will be used to update noise estimate.
pmax=-99
do i=1,8
ib=(i-1)*NSPM+1
ie=ib+NSPM-1
pow(i)=dot_product(cdat(ib:ie),cdat(ib:ie))*rms**2
if( pow(i) .gt. pmax ) then
pmax=pow(i)
endif
enddo
pavg=sum(pow)/8.0
! Short ping decoder uses squared-signal spectrum to determine where to
! center a 3-frame analysis window and attempts to decode each of the
! 3 frames along with 2- and 3-frame averages.
np=8*NSPM
call msk144spd(cdat,np,ntol,nsuccess,msgreceived,fc,fest,tdec)
if( nsuccess .eq. 1 ) then
tdec=tsec+tdec
decsym=' & '
goto 999
endif
! If short ping decoder doesn't find a decode, then 4-, 5-, and 7-frame averages
! spanning the first 7 frames of the block.
do iavg=1,NPATTERNS
iavmask=iavpatterns(1:8,iavg)
navg=sum(iavmask)
ndf=nint(7.0/navg)
npeaks=2
call msk144sync(cdat(1:8*NSPM),8,ntol,ndf,iavmask,npeaks,fc,fest,npkloc,nsyncsuccess,c)
if( nsyncsuccess .eq. 0 ) cycle
do ipk=1,npeaks
do is=1,3
ic0=npkloc(ipk)
if(is.eq.2) ic0=max(1,ic0-1)
if(is.eq.3) ic0=min(NSPM,ic0+1)
ct=cshift(c,ic0-1)
call msk144decodeframe(ct,msgreceived,ndecodesuccess)
if(ndecodesuccess .gt. 0) then
tdec=tsec+xmc(iavg)*tframe
decsym=' ^ '
goto 999
endif
enddo !Slicer dither
enddo !Peak loop
enddo
msgreceived=' '
! no decode - update noise level used for calculating displayed snr.
if( pnoise .lt. 0 ) then ! initialize noise level
pnoise=pavg
elseif( pavg .gt. pnoise ) then ! noise level is slow to rise
pnoise=0.9*pnoise+0.1*pavg
elseif( pavg .lt. pnoise ) then ! and quick to fall
pnoise=pavg
endif
return
999 continue
! successful decode - estimate snr !!! noise estimate needs work
if( pnoise .gt. 0.0 ) then
snr0=10.0*log10(pmax/pnoise-1.0)
else
snr0=0.0
endif
nsnr=nint(snr0)
!!!! Temporary - dupe check. Only print if new message, or higher snr.
if( msgreceived .eq. msglast .and. nsnr .le. nsnrlast ) return
msglast=msgreceived
nsnrlast=nsnr
if( nsnr .lt. -8 ) nsnr=-8
if( nsnr .gt. 24 ) nsnr=24
write(line,1020) nutc0,nsnr,tdec,nint(fest),decsym,msgreceived,char(0)
1020 format(i6.6,i4,f5.1,i5,a3,a22,a1)
return
end subroutine mskrtd