69 lines
1.7 KiB
Plaintext
69 lines
1.7 KiB
Plaintext
real function fchisq65(cx,npts,fsample,nflip,a,ccfmax,dtmax)
|
|
|
|
use timer_module, only: timer
|
|
|
|
parameter (NMAX=60*12000) !Samples per 60 s
|
|
complex cx(npts)
|
|
real a(5)
|
|
complex w,wstep,z
|
|
real ss(3000)
|
|
complex csx(0:NMAX/8)
|
|
data twopi/6.283185307/a1,a2,a3/99.,99.,99./
|
|
save
|
|
|
|
call timer('fchisq65',0)
|
|
baud=11025.0/4096.0
|
|
nsps=nint(fsample/baud) !Samples per symbol
|
|
nsph=nsps/2 !Samples per half-symbol
|
|
ndiv=16 !Output ss() steps per symbol
|
|
nout=ndiv*npts/nsps
|
|
dtstep=1.0/(ndiv*baud) !Time per output step
|
|
|
|
if(a(1).ne.a1 .or. a(2).ne.a2 .or. a(3).ne.a3) then
|
|
a1=a(1)
|
|
a2=a(2)
|
|
a3=a(3)
|
|
|
|
! Mix and integrate the complex signal
|
|
csx(0)=0.
|
|
w=1.0
|
|
x0=0.5*(npts+1)
|
|
s=2.0/npts
|
|
do i=1,npts
|
|
x=s*(i-x0)
|
|
if(mod(i,100).eq.1) then
|
|
p2=1.5*x*x - 0.5
|
|
dphi=(a(1) + x*a(2) + p2*a(3)) * (twopi/fsample)
|
|
wstep=cmplx(cos(dphi),sin(dphi))
|
|
endif
|
|
w=w*wstep
|
|
csx(i)=csx(i-1) + w*cx(i)
|
|
enddo
|
|
endif
|
|
|
|
! Compute whole-symbol powers at 1/16-symbol steps.
|
|
fac=1.e-4
|
|
do i=1,nout
|
|
j=nsps+(i-1)*nsps/16 !steps by 8 samples (1/16 of a symbol)
|
|
k=j-nsps
|
|
ss(i)=0.
|
|
if(k.ge.0 .and. j.le.npts) then
|
|
z=csx(j)-csx(k) ! difference over span of 128 pts
|
|
ss(i)=fac*(real(z)**2 + aimag(z)**2)
|
|
endif
|
|
enddo
|
|
|
|
ccfmax=0.
|
|
call timer('ccf2 ',0)
|
|
call ccf2(ss,nout,nflip,ccf,xlagpk)
|
|
call timer('ccf2 ',1)
|
|
if(ccf.gt.ccfmax) then
|
|
ccfmax=ccf
|
|
dtmax=xlagpk*dtstep
|
|
endif
|
|
fchisq65=-ccfmax
|
|
call timer('fchisq65',1)
|
|
|
|
return
|
|
end function fchisq65
|