mirror of
https://github.com/saitohirga/WSJT-X.git
synced 2024-11-03 16:01:18 -05:00
ea1f4962d7
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/map65@1541 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
120 lines
3.9 KiB
Fortran
120 lines
3.9 KiB
Fortran
subroutine filbig(id,nmax,f0,newdat,c4a,c4b,n4)
|
|
|
|
C Filter and downsample complex data for X and Y polarizations,
|
|
C stored in array id(4,nmax). Output is downsampled from 96000 Hz
|
|
C to 1500 Hz, and the low-pass filter has f_cutoff = 375 Hz and
|
|
C f_stop = 750 Hz.
|
|
|
|
parameter (NFFT1=5376000,NFFT2=77175)
|
|
integer*2 id(4,nmax) !Input data
|
|
complex c4a(NFFT2),c4b(NFFT2) !Output data
|
|
complex ca(NFFT1),cb(NFFT1) !FFTs of input
|
|
real*8 df
|
|
C Impulse response of filter (one side)
|
|
real halfpulse(8)
|
|
complex cfilt(NFFT2)
|
|
!Filter (complex; imag = 0)
|
|
real rfilt(NFFT2) !Filter (real)
|
|
integer plan1,plan2,plan3,plan4,plan5
|
|
logical first
|
|
include 'fftw3.f'
|
|
equivalence (rfilt,cfilt)
|
|
data first/.true./
|
|
data halfpulse/114.97547150,36.57879257,-20.93789101,
|
|
+ 5.89886379,1.59355187,-2.49138308,0.60910773,-0.04248129/
|
|
save
|
|
|
|
if(nmax.lt.0) go to 900
|
|
if(first) then
|
|
npatience=1
|
|
nflags=FFTW_ESTIMATE
|
|
if(npatience.eq.1) nflags=FFTW_ESTIMATE_PATIENT
|
|
if(npatience.eq.2) nflags=FFTW_MEASURE
|
|
if(npatience.eq.3) nflags=FFTW_PATIENT
|
|
if(npatience.eq.4) nflags=FFTW_EXHAUSTIVE
|
|
C Plan the FFTs just once
|
|
call sfftw_plan_dft_1d_(plan1,NFFT1,ca,ca,
|
|
+ FFTW_BACKWARD,nflags)
|
|
call sfftw_plan_dft_1d_(plan2,NFFT1,cb,cb,
|
|
+ FFTW_BACKWARD,nflags)
|
|
call sfftw_plan_dft_1d_(plan3,NFFT2,c4a,c4a,
|
|
+ FFTW_FORWARD,nflags)
|
|
call sfftw_plan_dft_1d_(plan4,NFFT2,c4b,c4b,
|
|
+ FFTW_FORWARD,nflags)
|
|
call sfftw_plan_dft_1d_(plan5,NFFT2,cfilt,cfilt,
|
|
+ FFTW_BACKWARD,nflags)
|
|
|
|
C Convert impulse response to filter function
|
|
do i=1,NFFT2
|
|
cfilt(i)=0.
|
|
enddo
|
|
fac=0.00625/NFFT1
|
|
cfilt(1)=fac*halfpulse(1)
|
|
do i=2,8
|
|
cfilt(i)=fac*halfpulse(i)
|
|
cfilt(NFFT2+2-i)=fac*halfpulse(i)
|
|
enddo
|
|
call sfftw_execute_(plan5)
|
|
|
|
base=cfilt(NFFT2/2+1)
|
|
do i=1,NFFT2
|
|
rfilt(i)=real(cfilt(i))-base
|
|
enddo
|
|
|
|
df=96000.d0/NFFT1
|
|
first=.false.
|
|
endif
|
|
|
|
C When new data comes along, we need to compute a new "big FFT"
|
|
C If we just have a new f0, continue with the existing ca and cb.
|
|
|
|
if(newdat.ne.0) then
|
|
nz=min(nmax,NFFT1)
|
|
do i=1,nz
|
|
ca(i)=cmplx(float(int(id(1,i))),float(int(id(2,i))))
|
|
cb(i)=cmplx(float(int(id(3,i))),float(int(id(4,i))))
|
|
enddo
|
|
|
|
if(nmax.lt.NFFT1) then
|
|
do i=nmax+1,NFFT1
|
|
ca(i)=0.
|
|
cb(i)=0.
|
|
enddo
|
|
endif
|
|
call sfftw_execute_(plan1)
|
|
call sfftw_execute_(plan2)
|
|
newdat=0
|
|
endif
|
|
|
|
C NB: f0 is the frequency at which we want our filter centered.
|
|
C i0 is the bin number in ca and cb closest to f0.
|
|
|
|
i0=nint(f0/df) + 1
|
|
nh=NFFT2/2
|
|
do i=1,nh !Copy data into c4a and c4b,
|
|
j=i0+i-1 !and apply the filter function
|
|
c4a(i)=rfilt(i)*ca(j)
|
|
c4b(i)=rfilt(i)*cb(j)
|
|
enddo
|
|
do i=nh+1,NFFT2
|
|
j=i0+i-1-NFFT2
|
|
if(j.lt.1) j=j+NFFT1 !NFFT1 was NFFT2
|
|
c4a(i)=rfilt(i)*ca(j)
|
|
c4b(i)=rfilt(i)*cb(j)
|
|
enddo
|
|
|
|
C Do the short reverse transform, to go back to time domain.
|
|
call sfftw_execute_(plan3)
|
|
call sfftw_execute_(plan4)
|
|
n4=min(nmax/64,NFFT2)
|
|
go to 999
|
|
|
|
900 call sfftw_destroy_plan_(plan1)
|
|
call sfftw_destroy_plan_(plan2)
|
|
call sfftw_destroy_plan_(plan3)
|
|
call sfftw_destroy_plan_(plan4)
|
|
call sfftw_destroy_plan_(plan5)
|
|
|
|
999 return
|
|
end
|