WSJT-X/lib/decoder.f90

154 lines
4.1 KiB
Fortran
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subroutine decoder(ss,c0)
! Decoder for JT9.
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
real ss(184,NSMAX)
character*22 msg
character*33 line
character*80 fmt
character*20 datetime
real*4 ccfred(NSMAX)
logical ccfok(NSMAX)
integer*1 i1SoftSymbols(207)
integer*2 id2
integer ii(1)
complex c0(NDMAX)
complex c1(NDMAX)
common/npar/nutc,ndiskdat,ntrperiod,nfqso,newdat,npts8,nfa,nfb,ntol, &
kin,nzhsym,nsave,nagain,ndepth,nrxlog,nfsample,datetime
common/tracer/limtrace,lu
save
call timer('decoder ',0)
open(13,file='decoded.txt',status='unknown')
ntrMinutes=ntrperiod/60
newdat=1
nsynced=0
ndecoded=0
limit=5000
ccflim=4.0
if(ndepth.ge.2) then
limit=50000
ccflim=3.0
endif
if(ndepth.ge.3) then
limit=200000
ccflim=2.5
endif
nsps=0
if(ntrMinutes.eq.1) then
nsps=6912
df3=1500.0/2048.0
fmt='(i4.4,i4,i5,f6.1,f8.0,i4,3x,a22)'
else if(ntrMinutes.eq.2) then
nsps=15360
df3=1500.0/2048.0
fmt='(i4.4,i4,i5,f6.1,f8.1,i4,3x,a22)'
else if(ntrMinutes.eq.5) then
nsps=40960
df3=1500.0/6144.0
fmt='(i4.4,i4,i5,f6.1,f8.1,i4,3x,a22)'
else if(ntrMinutes.eq.10) then
nsps=82944
df3=1500.0/12288.0
fmt='(i4.4,i4,i5,f6.1,f8.2,i4,3x,a22)'
else if(ntrMinutes.eq.30) then
nsps=252000
df3=1500.0/32768.0
fmt='(i4.4,i4,i5,f6.1,f8.2,i4,3x,a22)'
endif
if(nsps.eq.0) stop 'Error: bad TRperiod' !Better: return an error code###
kstep=nsps/2
tstep=kstep/12000.0
do nqd=1,0,-1
if(nqd.eq.1) then
nfa1=nfqso-ntol
nfb1=nfqso+ntol
else
nfa1=nfa
nfb1=nfb
endif
call timer('sync9 ',0)
! Compute ccfred()
call sync9(ss,nzhsym,tstep,df3,nfa1,nfb1,ntol,nfqso,ccfred,ia,ib,ipk)
call timer('sync9 ',1)
ccfok=.false.
ccfok(max(ipk-1,1):min(ipk+1,NSMAX))=.true.
if(nqd.eq.1) then
ia1=ia
ib1=ib
else
do i=ia+9,ib-25
t1=ccfred(i)/(sum(ccfred(i-8:i-6)/3.0))
t2=ccfred(i)/(sum(ccfred(i+23:i+25)/3.0))
if(t1.ge.ccflim .and. t2.ge.ccflim) ccfok(i)=.true.
enddo
ccfok(ia1:ib1)=.false.
endif
nRxLog=0
fgood=0.
nsps8=nsps/8
df8=1500.0/nsps8
sbest=-1.0
dblim=db(864.0/nsps8) - 26.2
i1=max(nint((nfqso-1000)/df3 - 10),ia)
i2=min(nint((nfqso-1000)/df3 + 10),ib)
ii=maxloc(ccfred(i1:i2))
i00=ii(1) + i1 - 1
do i=ia,ib
f=(i-1)*df3
if(.not.ccfok(i)) cycle
if(nqd.eq.1 .or. &
(ccfred(i).ge.3.0 .and. abs(f-fgood).gt.10.0*df8)) then
call timer('decode9a',0)
fpk=1000.0 + df3*(i-1)
c1(1:npts8)=conjg(c0(1:npts8))
call decode9a(c1,npts8,nsps8,fpk,syncpk,snrdb,xdt,freq,drift, &
i1SoftSymbols)
call timer('decode9a',1)
call timer('decode9 ',0)
call decode9(i1SoftSymbols,limit,nlim,msg)
call timer('decode9 ',1)
sync=(syncpk+1)/4.0
if(sync.lt.0.0 .or. snrdb.lt.dblim-2.0) sync=0.0
nsync=sync
if(nsync.gt.10) nsync=10
nsnr=nint(snrdb)
ndrift=nint(drift/df3)
if(msg.ne.' ') then
write(*,fmt) nutc,nsync,nsnr,xdt,freq,ndrift,msg
write(13,fmt) nutc,nsync,nsnr,xdt,freq,ndrift,msg
fgood=f
nsynced=1
ndecoded=1
ccfok(max(ia,i-3):min(ib,i+11))=.false.
call flush(6)
endif
endif
enddo
call flush(6)
enddo
write(*,1010) nsynced,ndecoded
1010 format('<DecodeFinished>',2i4)
call flush(6)
close(13)
call timer('decoder ',1)
if(nstandalone.eq.0) call timer('decoder ',101)
return
end subroutine decoder