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In submode JT65C, downsample the data twice: once so that sync tone

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goes to f=0, once so it goes to -355.297 Hz.


git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@6504 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
This commit is contained in:
Joe Taylor 2016-03-02 19:44:09 +00:00
parent ce24320476
commit e762cba31e
1 changed files with 10 additions and 2 deletions
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12
lib/decode65a.f90
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@ -8,7 +8,8 @@ subroutine decode65a(dd,npts,newdat,nqd,f0,nflip,mode65,ntrials, &
parameter (NMAX=60*12000) !Samples per 60 s
real*4 dd(NMAX) !92 MB: raw data from Linrad timf2
complex cx(NMAX/8) !Data at 1378.125 samples/s
complex cx(NMAX/8) !Data at 1378.125 sps
complex cx1(NMAX/8) !Data at 1378.125 sps, offset by 355.3 Hz
complex c5x(NMAX/32) !Data at 344.53125 Hz
complex c5a(512)
real s2(66,126)
@ -23,6 +24,7 @@ subroutine decode65a(dd,npts,newdat,nqd,f0,nflip,mode65,ntrials, &
! Mix sync tone to baseband, low-pass filter, downsample to 1378.125 Hz
call timer('filbig ',0)
call filbig(dd,npts,f0,newdat,cx,n5,sq0)
if(mode65.eq.4) call filbig(dd,npts,f0+355.297852,newdat,cx1,n5,sq0)
call timer('filbig ',1)
! NB: cx has sample rate 12000*77125/672000 = 1378.125 Hz
@ -42,6 +44,7 @@ subroutine decode65a(dd,npts,newdat,nqd,f0,nflip,mode65,ntrials, &
dtbest=dtbest+0.003628 ! remove decimation filter and coh. integrator delay
dt=dtbest !return new, improved estimate of dt
sync2=3.7e-4*ccfbest/sq0 !Constant is empirical
if(mode65.eq.4) cx=cx1
! Apply AFC corrections to the time-domain signal
! Now we are back to using the 1378.125 Hz sample rate, enough to
@ -71,7 +74,12 @@ subroutine decode65a(dd,npts,newdat,nqd,f0,nflip,mode65,ntrials, &
do i=1,66
jj=i
if(mode65.eq.2) jj=2*i-1
if(mode65.eq.4) jj=4*i-3
if(mode65.eq.4) then
! jj=4*i-3
ff=4*(i-1)*df - 355.297852
jj=nint(ff/df)+1
if(jj.lt.1) jj=jj+512
endif
s2(i,k)=real(c5a(jj))**2 + aimag(c5a(jj))**2
enddo
enddo