WSJT-X/lib/qra64a.f90
Joe Taylor 421524d88c Fix the broken S/N calculation for QRA64.
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@6888 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
2016-07-07 19:27:03 +00:00

148 lines
3.3 KiB
Fortran

subroutine qra64a(dd,nf1,nf2,nfqso,ntol,mycall_12,sync,nsnr,dtx,nfreq, &
decoded,nft)
use packjt
parameter (NFFT=2*6912,NH=NFFT/2,NZ=5760)
character decoded*22,mycall_12*12,mycall*6
character*1 mark(0:5),zplot(0:63)
logical ltext
integer icos7(0:6)
integer ipk(1)
integer jpk(1)
integer dat4(12)
real dd(60*12000)
real s(NZ)
real savg(NZ)
real blue(0:25)
real red0(NZ)
real red(NZ)
real x(NFFT)
complex cx(0:NH)
equivalence (x,cx)
data icos7/2,5,6,0,4,1,3/ !Costas 7x7 pattern
data mark/' ','.','-','+','X','$'/
common/qra64com/ss(NZ,194),s3(0:63,1:63),ccf(NZ,0:25)
save
decoded=' '
nft=99
nsnr=-30
nsps=6912
istep=nsps/2
nsteps=52*12000/istep - 2
ia=1-istep
savg=0.
df=12000.0/NFFT
do j=1,nsteps
ia=ia+istep
ib=ia+nsps-1
x(1:nsps)=1.2e-4*dd(ia:ib)
x(nsps+1:)=0.0
call four2a(x,nfft,1,-1,0) !r2c FFT
do i=1,NZ
s(i)=real(cx(i))**2 + aimag(cx(i))**2
enddo
ss(1:NZ,j)=s
savg=savg+s
enddo
savg=savg/nsteps
fa=max(nf1,nfqso-ntol)
fb=min(nf2,nfqso+ntol)
ia=nint(fa/df)
ib=nint(fb/df)
call pctile(savg(ia),ib-ia+1,45,base)
savg=savg/base - 1.0
ss=ss/base
red0=0.
fac=1.0/sqrt(21.0)
sync=0.
do if0=ia,ib
red0(if0)=0.
do j=0,25
t=-3.0
do n=0,6
i=if0 + 2*icos7(n)
t=t + ss(i,1+2*n+j) + ss(i,1+2*n+j+78) + ss(i,1+2*n+j+154)
enddo
ccf(if0,j)=fac*t
if(ccf(if0,j).gt.red0(if0)) then
red0(if0)=ccf(if0,j)
if(red0(if0).gt.sync) then
sync=red0(if0)
f0=if0*df
dtx=j*istep/12000.0 - 1.0
i0=if0
j0=j
endif
endif
enddo
enddo
red(ia:ib)=0.
rewind 73
do i=ia+3,ib-3
r1=red0(i)
red0(i)=0.
r0=max(red0(i-3),red0(i-2),red0(i+2),red0(i+3))
red0(i)=r1
red(i)=max(0.0,r1-r0)
write(73,3001) i*df,red(i),red0(i),r0
3001 format(4f12.3)
enddo
flush(73)
write(17) ia,ib,red(ia:ib)
close(17)
if0=nint(f0/df)
nfreq=nint(f0)
blue(0:25)=ccf(if0,0:25)
jpk=maxloc(blue)
xpk=jpk(1) + 1.0
call slope(blue,26,xpk)
! Insist on at least 10 correct hard decisions in the 21 Costas bins.
nhard=0
do n=0,6
ipk=maxloc(ss(i0:i0+63,1+j0+2*n)) - 1
i=abs(ipk(1)-2*icos7(n))
if(i.le.1) nhard=nhard+1
ipk=maxloc(ss(i0:i0+63,1+j0+2*n+78)) - 1
i=abs(ipk(1)-2*icos7(n))
if(i.le.1) nhard=nhard+1
ipk=maxloc(ss(i0:i0+63,1+j0+2*n+154)) - 1
i=abs(ipk(1)-2*icos7(n))
if(i.le.1) nhard=nhard+1
enddo
! print*,'a',nhard,nhard,nhard
if(nhard.lt.6) go to 900
do i=0,63
k=i0 + 2*i
jj=j0+13
do j=1,63
jj=jj+2
s3(i,j)=ss(k,jj)
if(j.eq.32) jj=jj+14 !Skip over the middle Costas array
enddo
enddo
if(sync.gt.1.0) nsnr=nint(10.0*log10(sync) - 38.0)
! if(sync.lt.12.8) go to 900 !### Temporary ###
mycall=mycall_12(1:6) !### May need fixing ###
call packcall(mycall,nmycall,ltext)
call qra64_dec(s3,nmycall,dat4,irc) !Attempt decoding
if(irc.ge.0) then
call unpackmsg(dat4,decoded) !Unpack the user message
call fmtmsg(decoded,iz)
nft=100 + irc
endif
900 return
end subroutine qra64a