WSJT-X/lib/decoder.f90

113 lines
3.0 KiB
Fortran
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subroutine decoder(ntrSeconds,ndepth,nRxLog,c0)
! Decoder for JT9. Can run stand-alone, reading data from *.wav files;
! or as the back end of wsjt-x, with data placed in a shared memory region.
! NB: For unknown reason, ***MUST*** be compiled by g95 with -O0 !!!
parameter (NMAX=1800*12000) !Total sample intervals per 30 minutes
parameter (NDMAX=1800*1500) !Sample intervals at 1500 Hz rate
parameter (NSMAX=22000) !Max length of saved spectra
character*22 msg
character*33 line
real*4 ccfred(NSMAX)
integer*1 i1SoftSymbols(207)
integer*2 id2
complex c0(NDMAX)
common/jt9com/ss(184,NSMAX),savg(NSMAX),id2(NMAX),nutc,ndiskdat, &
ntr,nfqso,nagain,newdat,npts8,nfb,ntol,kin,nsynced,ndecoded
logical first
data first/.true./
save
ntrMinutes=ntrSeconds/60
newdat=1
nsynced=0
ndecoded=0
limit=1000
if(ndepth.ge.2) limit=20000
if(ndepth.ge.3) limit=100000
nsps=0
if(ntrMinutes.eq.1) then
nsps=6912
df3=1500.0/2048.0
else if(ntrMinutes.eq.2) then
nsps=15360
df3=1500.0/2048.0
else if(ntrMinutes.eq.5) then
nsps=40960
df3=1500.0/6144.0
else if(ntrMinutes.eq.10) then
nsps=82944
df3=1500.0/12288.0
else if(ntrMinutes.eq.30) then
nsps=252000
df3=1500.0/32768.0
endif
if(nsps.eq.0) stop 'Error: bad TRperiod' !Better: return an error code###
! Now do the decoding
kstep=nsps/2
tstep=kstep/12000.0
! Get sync, approx freq
call sync9(ss,tstep,df3,ntol,nfqso,ccfred,ia,ib,ipk)
open(13,file='decoded.txt',status='unknown')
rewind 13
if(first) then
open(14,file='wsjtx_rx.log',status='unknown',position='append')
first=.false.
endif
if(iand(nRxLog,2).ne.0) rewind 14
if(iand(nRxLog,1).ne.0) then
! Write date and time to lu 14
endif
fgood=0.
df8=1500.0/(nsps/8)
sbest=0.
do i=ia,ib
f=(i-1)*df3
if((i.eq.ipk .or. ccfred(i).ge.3.0) .and. f.gt.fgood+10.0*df8) then
call spec9(c0,npts8,nsps,f,fpk,xdt,i1SoftSymbols)
call decode9(i1SoftSymbols,limit,nlim,msg)
snr=10.0*log10(ccfred(i)) - 10.0*log10(2500.0/df3) + 2.0
sync=ccfred(i) - 2.0
if(sync.lt.0.0) sync=0.0
nsync=sync
if(nsync.gt.10) nsync=10
nsnr=nint(snr)
width=0.0
if(ccfred(i).gt.sbest .and. fgood.eq.0.0) then
sbest=ccfred(i)
write(line,1010) nutc,nsync,nsnr,xdt,1000.0+fpk,width
if(nsync.gt.0) nsynced=1
endif
if(msg.ne.' ') then
write(13,1010) nutc,nsync,nsnr,xdt,1000.0+fpk,width,msg
1010 format(i4.4,i4,i5,f6.1,f8.2,f6.2,3x,a22)
write(14,1010) nutc,nsync,nsnr,xdt,1000.0+fpk,width,msg
fgood=f
nsynced=1
ndecoded=1
endif
endif
enddo
if(fgood.eq.0.0) then
write(13,1020) line
write(14,1020) line
1020 format(a33)
endif
call flush(13)
call flush(14)
close(13)
return
end subroutine decoder