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Correct the FT8 downsample factor to be exactly 1/64.

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git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@7779 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
This commit is contained in:
Joe Taylor 2017-07-03 19:01:38 +00:00
parent e1b2bdef06
commit 4bce86d61e
2 changed files with 17 additions and 11 deletions
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26
lib/fsk4hf/ft8b.f90
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@ -13,7 +13,7 @@ subroutine ft8b(dd0,nfqso,f1,xdt,nharderrors,dmin,nbadcrc,message,xsnr)
integer*1 decoded(KK),apmask(3*ND),cw(3*ND) integer*1 decoded(KK),apmask(3*ND),cw(3*ND)
integer itone(NN) integer itone(NN)
integer icos7(0:6) integer icos7(0:6)
complex cd0(NP2) complex cd0(3125)
complex csync(0:6,32) complex csync(0:6,32)
complex ctwk(32) complex ctwk(32)
complex csymb(32) complex csymb(32)
@ -193,30 +193,34 @@ subroutine ft8_downsample(dd,f0,c1)
! Downconvert to complex data sampled at 187.5 Hz, 32 samples/symbol ! Downconvert to complex data sampled at 187.5 Hz, 32 samples/symbol
parameter (NMAX=15*12000,NFFT2=2812) parameter (NMAX=15*12000)
parameter (NFFT1=200000,NFFT2=3125) !200000/64 = 3125
complex c1(0:NFFT2-1) complex c1(0:NFFT2-1)
complex cx(0:NMAX/2) complex cx(0:NFFT1/2)
real dd(NMAX),x(NMAX) real dd(NMAX),x(NFFT1)
equivalence (x,cx) equivalence (x,cx)
save x save x
df=12000.0/NMAX df=12000.0/NFFT1
x=dd x(1:NMAX)=dd
call four2a(cx,NMAX,1,-1,0) !r2c FFT to freq domain x(NMAX+1:NFFT1)=0. !Zero-pad the x array
baud=12000.0/(32.0*64.0) call four2a(cx,NFFT1,1,-1,0) !r2c FFT to freq domain
baud=12000.0/2048.0
i0=nint(f0/df) i0=nint(f0/df)
ft=f0+8.0*baud ft=f0+8.0*baud
it=min(nint(ft/df),NMAX/2-1) it=min(nint(ft/df),NFFT1/2)
fb=f0-1.0*baud fb=f0-1.0*baud
ib=max(1,nint(fb/df)) ib=max(1,nint(fb/df))
k=0 k=0
c1=cmplx(0.0,0.0) c1=0.
do i=ib,it do i=ib,it
c1(k)=cx(i) c1(k)=cx(i)
k=k+1 k=k+1
enddo enddo
c1=cshift(c1,i0-ib) c1=cshift(c1,i0-ib)
call four2a(c1,NFFT2,1,1,1) !c2c FFT back to time domain call four2a(c1,NFFT2,1,1,1) !c2c FFT back to time domain
c1=c1/(NMAX*NFFT2) fac=1.0/sqrt(float(NFFT1)*NFFT2)
c1=fac*c1
return return
end subroutine ft8_downsample end subroutine ft8_downsample

2
lib/refspectrum.f90
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@ -25,6 +25,8 @@ subroutine refspectrum(id2,id2b,kk,bclear,brefspec,buseref,fname)
data first/.true./,blastuse/.false./ data first/.true./,blastuse/.false./
save save
print*,fname
if(first) then if(first) then
pi=4.0*atan(1.0) pi=4.0*atan(1.0)
do i=0,NFFT-1 do i=0,NFFT-1