2016-09-30 11:56:55 -04:00
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subroutine msk144_freq_search(cdat,fc,if1,if2,delf,nframes,navmask,cb, &
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2016-09-30 21:30:41 -04:00
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cdat2,xmax,bestf,cs,xccs)
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2016-09-30 11:56:55 -04:00
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parameter (NSPM=864,NZ=7*NSPM)
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complex cdat(NZ)
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complex cdat2(NZ)
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complex c(NSPM) !Coherently averaged complex data
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complex ct2(2*NSPM)
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complex cs(NSPM)
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complex cb(42) !Complex waveform for sync word
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complex cc(0:NSPM-1)
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real xcc(0:NSPM-1)
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real xccs(0:NSPM-1)
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integer navmask(nframes) !Tells which frames to average
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navg=sum(navmask)
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n=nframes*NSPM
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fac=1.0/(48.0*sqrt(float(navg)))
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2016-10-03 13:08:02 -04:00
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do ifr=if1,if2 !Find freq that maximizes sync
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2016-09-30 11:56:55 -04:00
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ferr=ifr*delf
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call tweak1(cdat,n,-(fc+ferr),cdat2)
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c=0
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sumw=0.
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do i=1,nframes
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ib=(i-1)*NSPM+1
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ie=ib+NSPM-1
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if(navmask(i).eq.1) c=c + cdat2(ib:ie)
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enddo
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cc=0
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ct2(1:NSPM)=c
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ct2(NSPM+1:2*NSPM)=c
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do ish=0,NSPM-1
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cc(ish)=dot_product(ct2(1+ish:42+ish)+ct2(337+ish:378+ish),cb(1:42))
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enddo
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xcc=abs(cc)
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xb=maxval(xcc)*fac
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if(xb.gt.xmax) then
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xmax=xb
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bestf=ferr
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cs=c
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xccs=xcc
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endif
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enddo
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return
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end subroutine msk144_freq_search
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