WSJT-X/mtdecode.f
Joe Taylor 9590ff5f43 More code cleanup: silenced many g95 warning messages about variables "set
but not used".


git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/trunk@275 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
2006-09-06 19:51:52 +00:00

145 lines
4.1 KiB
Fortran

subroutine mtdecode(dat,jz,nz,MinSigdB,MinWidth,
+ NQRN,DFTolerance,istart,pick,cfile6,ps0)
C Decode Multi-Tone FSK441 mesages.
real dat(jz) !Raw audio data
integer NQRN
integer DFTolerance
logical pick
character*6 cfile6,cf*1
real sigdb(3100) !Detected signal in dB, sampled at 20 ms
real work(3100)
integer indx(3100)
real pingdat(3,100)
real ps(128)
real ps0(128)
character msg*40,msg3*3
character*90 line
common/ccom/nline,tping(100),line(100)
slim=MinSigdB
wmin=0.001*MinWidth * (19.95/20.0)
nf1=-DFTolerance
nf2=DFTolerance
msg3=' '
dt=1.0/11025.0
C Find signal power at suitable intervals to search for pings.
istep=221
dtbuf=istep/11025.
do n=1,nz
s=0.
ib=n*istep
ia=ib-istep+1
do i=ia,ib
s=s+dat(i)**2
enddo
sigdb(n)=s/istep
enddo
!#####################################################################
if(.not.pick) then
! Remove initial transient from sigdb
call indexx(nz,sigdb,indx)
imax=0
do i=1,50
if(indx(i).gt.50) go to 10
imax=max(imax,indx(i))
enddo
10 do i=1,50
if(indx(nz+1-i).gt.50) go to 20
imax=max(imax,indx(nz+1-i))
enddo
20 imax=imax+6 !Safety margin
base1=sigdb(indx(nz/2))
do i=1,imax
sigdb(i)=base1
enddo
endif
!##################################################################
call smooth(sigdb,nz)
C Remove baseline and one dB for good measure.
call pctile (sigdb,work,nz,50,base1)
do i=1,nz
sigdb(i)=dB(sigdb(i)/base1) - 1.0
enddo
call ping(sigdb,nz,dtbuf,slim,wmin,pingdat,nping)
C If this is a "mouse pick" and no ping was found, force a pseudo-ping
C at center of data.
if(pick.and.nping.eq.0) then
if(nping.le.99) nping=nping+1
pingdat(1,nping)=0.5*jz*dt
pingdat(2,nping)=0.16
pingdat(3,nping)=1.0
endif
bigpeak=0.
do iping=1,nping
C Find starting place and length of data to be analyzed:
tstart=pingdat(1,iping)
width=pingdat(2,iping)
peak=pingdat(3,iping)
mswidth=10*nint(100.0*width)
jj=(tstart-0.02)/dt
if(jj.lt.1) jj=1
jjz=nint((width+0.02)/dt)+1
jjz=min(jjz,jz+1-jj)
C Compute average spectrum of this ping.
call spec441(dat(jj),jjz,ps,f0)
C Decode the message.
msg=' '
call longx(dat(jj),jjz,ps,DFTolerance,noffset,msg,
+ msglen,bauderr)
qrnlimit=4.4*1.5**(5.0-NQRN)
if(NQRN.eq.0) qrnlimit=99.
if(msglen.eq.0) go to 100
C Assemble a signal report:
nwidth=0
if(width.ge.0.04) nwidth=1 !These might depend on NSPD
if(width.ge.0.12) nwidth=2
if(width.gt.1.00) nwidth=3
nstrength=6
if(peak.ge.11.0) nstrength=7
if(peak.ge.17.0) nstrength=8
if(peak.ge.23.0) nstrength=9
! if(peak.gt.5.0 .and.mswidth.ge.100) then
! call specsq(dat(jj),jjz,DFTolerance,0,noffset2)
! noffset=noffset2
! endif
C Discard this ping if DF outside tolerance limits or bauderr too big.
C (However, if the ping was mouse-picked, proceed anyway.)
if(.not.pick .and. ((noffset.lt.nf1 .or. noffset.gt.nf2) .or.
+ (abs(bauderr).gt.qrnlimit))) goto 100
C If it's the best ping yet, save the spectrum:
if(peak.gt.bigpeak) then
bigpeak=peak
do i=1,128
ps0(i)=ps(i)
enddo
endif
tstart=tstart + dt*(istart-1)
cf=' '
if(nline.le.99) nline=nline+1
tping(nline)=tstart
write(line(nline),1050) cfile6,tstart,mswidth,int(peak),
+ nwidth,nstrength,noffset,msg3,msg,cf
1050 format(a6,f5.1,i5,i3,1x,2i1,i5,1x,a3,1x,a40,1x,a1)
100 enddo
return
end