WSJT-X/lib/decoder.f90
Joe Taylor c35b1c13ad Go back to old version of pctile, using a full sort.
Better calc of snrdb, especially for strong signals.


git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@2719 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
2012-11-12 18:28:28 +00:00

123 lines
3.2 KiB
Fortran

subroutine decoder(ntrSeconds,ndepth,nRxLog,c00)
! Decoder for JT9.
! 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
character*80 fmt
real*4 ccfred(NSMAX)
integer*1 i1SoftSymbols(207)
integer*2 id2
complex c0(NDMAX),c00(NDMAX)
common/jt9com/ss0(184,NSMAX),savg(NSMAX),id2(NMAX),nutc0,ndiskdat, &
ntr,nfqso,newdat,npts80,nfb,ntol,kin,nsynced,ndecoded
common/jt9comB/ss(184,NSMAX),c0
logical first
data first/.true./
save
if(newdat.ne.0) then
ss=ss0
c0=c00
nutc=nutc0
npts8=npts80
endif
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
fmt='(i4.4,i4,i5,f6.1,f8.0,f6.2,3x,a22)'
else if(ntrMinutes.eq.2) then
nsps=15360
df3=1500.0/2048.0
fmt='(i4.4,i4,i5,f6.1,f8.1,f6.2,3x,a22)'
else if(ntrMinutes.eq.5) then
nsps=40960
df3=1500.0/6144.0
fmt='(i4.4,i4,i5,f6.1,f8.1,f6.2,3x,a22)'
else if(ntrMinutes.eq.10) then
nsps=82944
df3=1500.0/12288.0
fmt='(i4.4,i4,i5,f6.1,f8.2,f6.2,3x,a22)'
else if(ntrMinutes.eq.30) then
nsps=252000
df3=1500.0/32768.0
fmt='(i4.4,i4,i5,f6.1,f8.2,f6.2,3x,a22)'
endif
if(nsps.eq.0) stop 'Error: bad TRperiod' !Better: return an error code###
kstep=nsps/2
tstep=kstep/12000.0
call sync9(ss,tstep,df3,ntol,nfqso,ccfred,ia,ib,ipk) ! Get sync, approx freq
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,snrdb,i1SoftSymbols)
call decode9(i1SoftSymbols,limit,nlim,msg)
! snr=10.0*log10(ccfred(i)) - 10.0*log10(2500.0/df3) + 2.0
snr=snrdb
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,fmt) nutc,nsync,nsnr,xdt,1000.0+fpk,width
if(nsync.gt.0) nsynced=1
endif
if(msg.ne.' ') then
write(13,fmt) nutc,nsync,nsnr,xdt,1000.0+fpk,width,msg
write(14,fmt) 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