WSJT-X/lib/msk144sync.f90
Steven Franke 665b8dc85a More work on real-time decoder for msk144.
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@7107 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
2016-09-22 19:42:05 +00:00

107 lines
2.3 KiB
Fortran

subroutine msk144sync(cdat,n,ntol,ndf,navmask,npeaks,fest,npklocs,nsuccess,c)
parameter (NSPM=864)
complex cdat(n)
complex cdat2(n)
complex c(NSPM) !Coherently averaged complex data
complex ct2(2*NSPM)
complex cs(NSPM)
complex cb(42) !Complex waveform for sync word
complex cc(0:NSPM-1)
integer s8(8)
integer iloc(1)
integer npklocs(npeaks)
integer navmask(8) ! defines which frames to average
real cbi(42),cbq(42)
real pkamps(npeaks)
real xcc(0:NSPM-1)
real xccs(0:NSPM-1)
real pp(12) !Half-sine pulse shape
logical first
data first/.true./
data s8/0,1,1,1,0,0,1,0/
save first,cb,fs,pi,twopi,dt,s8,pp
! call system_clock(count0,clkfreq)
if(first) then
pi=4.0*atan(1.0)
twopi=8.0*atan(1.0)
fs=12000.0
dt=1.0/fs
do i=1,12 !Define half-sine pulse
angle=(i-1)*pi/12.0
pp(i)=sin(angle)
enddo
! Define the sync word waveforms
s8=2*s8-1
cbq(1:6)=pp(7:12)*s8(1)
cbq(7:18)=pp*s8(3)
cbq(19:30)=pp*s8(5)
cbq(31:42)=pp*s8(7)
cbi(1:12)=pp*s8(2)
cbi(13:24)=pp*s8(4)
cbi(25:36)=pp*s8(6)
cbi(37:42)=pp(1:6)*s8(8)
cb=cmplx(cbi,cbq)
first=.false.
endif
navg=sum(navmask)
xmax=0.0
bestf=0.0
do ifr=-ntol,ntol,ndf !Find freq that maximizes sync
ferr=ifr
call tweak1(cdat,n,-(1500+ferr),cdat2)
c=0
do i=1,8
ib=(i-1)*NSPM+1
ie=ib+NSPM-1
if( navmask(i) .eq. 1 ) then
c(1:NSPM)=c(1:NSPM)+cdat2(ib:ie)
endif
enddo
cc=0
ct2(1:NSPM)=c
ct2(NSPM+1:2*NSPM)=c
do ish=0,NSPM-1
cc(ish)=dot_product(ct2(1+ish:42+ish)+ct2(336+ish:377+ish),cb(1:42))
enddo
xcc=abs(cc)
xb=maxval(xcc)/(48.0*sqrt(float(navg)))
if(xb.gt.xmax) then
xmax=xb
bestf=ferr
cs=c
xccs=xcc
endif
enddo
fest=1500+bestf
c=cs
xcc=xccs
! Find npeaks largest peaks
do ipk=1,npeaks
iloc=maxloc(xcc)
ic2=iloc(1)
npklocs(ipk)=ic2
pkamps(ipk)=xcc(ic2-1)
xcc(max(0,ic2-7):min(NSPM-1,ic2+7))=0.0
enddo
if( xmax .lt. 0.7 ) then
nsuccess=0
else
nsuccess=1
endif
return
end subroutine msk144sync