2013-05-14 14:29:01 +00:00
|
|
|
subroutine downsam9(c0,npts8,nsps8,newdat,nspsd,fpk,c2,nz2)
|
2012-11-27 15:38:03 +00:00
|
|
|
|
|
|
|
|
!Downsample to nspsd samples per symbol, info centered at fpk
|
|
|
|
|
|
|
|
|
|
parameter (NMAX=128*31500)
|
|
|
|
|
complex c0(0:npts8-1)
|
|
|
|
|
complex c1(0:NMAX-1)
|
|
|
|
|
complex c2(0:4096-1)
|
2012-11-27 16:48:50 +00:00
|
|
|
real s(1000)
|
2013-05-14 14:29:01 +00:00
|
|
|
save
|
2012-11-27 15:38:03 +00:00
|
|
|
|
|
|
|
|
nfft1=128*nsps8 !Forward FFT length
|
|
|
|
|
nh1=nfft1/2
|
|
|
|
|
df1=1500.0/nfft1
|
2013-05-14 14:29:01 +00:00
|
|
|
|
|
|
|
|
if(newdat.eq.1) then
|
|
|
|
|
fac=1.e-4
|
|
|
|
|
do i=0,npts8-1,2
|
|
|
|
|
c1(i)=fac*conjg(c0(i))
|
|
|
|
|
c1(i+1)=-fac*conjg(c0(i+1))
|
2012-11-27 16:48:50 +00:00
|
|
|
enddo
|
2013-05-14 14:29:01 +00:00
|
|
|
c1(npts8:)=0. !Zero the rest of c1
|
|
|
|
|
call four2a(c1,nfft1,1,-1,1) !Forward FFT
|
|
|
|
|
|
|
|
|
|
nadd=1.0/df1
|
|
|
|
|
j=250/df1
|
|
|
|
|
s=0.
|
|
|
|
|
do i=1,1000
|
|
|
|
|
do n=1,nadd
|
|
|
|
|
j=j+1
|
|
|
|
|
s(i)=s(i)+real(c1(j))**2 + aimag(c1(j))**2
|
|
|
|
|
enddo
|
|
|
|
|
! write(37,3001) i+1000,s(i),db(s(i)),nadd
|
|
|
|
|
!3001 format(i5,2f12.3,i8)
|
|
|
|
|
enddo
|
|
|
|
|
call pctile(s,1000,40,avenoise)
|
|
|
|
|
endif
|
|
|
|
|
|
2012-11-27 15:38:03 +00:00
|
|
|
ndown=nsps8/16 !Downsample factor
|
|
|
|
|
nfft2=nfft1/ndown !Backward FFT length
|
|
|
|
|
nh2=nfft2/2
|
|
|
|
|
|
|
|
|
|
fshift=fpk-1500.0
|
|
|
|
|
i0=nh1 + fshift/df1
|
2012-11-27 17:10:28 +00:00
|
|
|
fac=sqrt(1.0/avenoise)
|
2012-11-27 15:38:03 +00:00
|
|
|
do i=0,nfft2-1
|
|
|
|
|
j=i0+i
|
|
|
|
|
if(i.gt.nh2) j=j-nfft2
|
2012-11-27 16:48:50 +00:00
|
|
|
c2(i)=fac*c1(j)
|
2012-11-27 15:38:03 +00:00
|
|
|
enddo
|
|
|
|
|
|
|
|
|
|
call four2a(c2,nfft2,1,1,1) !Backward FFT
|
|
|
|
|
|
|
|
|
|
nspsd=nsps8/ndown
|
|
|
|
|
nz2=npts8/ndown
|
|
|
|
|
|
|
|
|
|
return
|
|
|
|
|
end subroutine downsam9
|
