mirror of
https://github.com/saitohirga/WSJT-X.git
synced 2024-11-30 08:08:39 -05:00
d91aed5aee
procedure; better window functions for some FFTs, resulting in better decoder performance; User-selectable colors for backgrounds of decoded messages. NB: more testing is desirable! git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@4951 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
61 lines
1.4 KiB
Fortran
61 lines
1.4 KiB
Fortran
subroutine symspec65(dd,npts,ss,nhsym,savg)
|
|
|
|
! Compute JT65 symbol spectra at half-symbol steps
|
|
|
|
parameter (NFFT=8192)
|
|
parameter (NSZ=3413) !NFFT*5000/12000
|
|
parameter (MAXHSYM=322)
|
|
real*8 hstep
|
|
real*4 dd(npts)
|
|
real*4 ss(MAXHSYM,NSZ)
|
|
real*4 savg(NSZ)
|
|
real*4 x(NFFT)
|
|
real*4 w(NFFT)
|
|
complex c(0:NFFT/2)
|
|
logical first
|
|
common/refspec/dfref,ref(NSZ)
|
|
equivalence (x,c)
|
|
data first/.true./
|
|
save /refspec/,first,w
|
|
|
|
hstep=2048.d0*12000.d0/11025.d0 !half-symbol = 2229.116 samples
|
|
nsps=nint(2*hstep)
|
|
df=12000.0/NFFT
|
|
nhsym=(npts-NFFT)/hstep
|
|
savg=0.
|
|
fac1=1.e-3
|
|
|
|
if(first) then
|
|
! Compute the FFT window
|
|
pi=4.0*atan(1.0)
|
|
width=0.25*nsps
|
|
do i=1,NFFT
|
|
z=(i-NFFT/2)/width
|
|
w(i)=exp(-z*z)
|
|
enddo
|
|
first=.false.
|
|
endif
|
|
|
|
do j=1,nhsym
|
|
i0=(j-1)*hstep
|
|
x=fac1*w*dd(i0+1:i0+NFFT)
|
|
call four2a(c,NFFT,1,-1,0) !r2c forward FFT
|
|
do i=1,NSZ
|
|
s=real(c(i))**2 + aimag(c(i))**2
|
|
ss(j,i)=s
|
|
savg(i)=savg(i)+s
|
|
enddo
|
|
enddo
|
|
savg=savg/nhsym
|
|
|
|
call flat65(ss,nhsym,MAXHSYM,NSZ,ref) !Flatten the 2d spectrum, saving
|
|
dfref=df ! the reference spectrum ref()
|
|
|
|
savg=savg/ref
|
|
do j=1,nhsym
|
|
ss(j,1:NSZ)=ss(j,1:NSZ)/ref
|
|
enddo
|
|
|
|
return
|
|
end subroutine symspec65
|