Reconfigure to optimize decoder for MF/LF (high coherence) channels.

This commit is contained in:
Steven Franke 2020-08-19 14:10:28 -05:00 committed by Bill Somerville
parent 7cb5511ed0
commit 782c779392
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2 changed files with 10 additions and 14 deletions

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@ -105,7 +105,7 @@ subroutine get_fst4_bitmetrics(cd,nss,hmod,nmax,nhicoh,bitmetrics,s4,badsync)
csum=csum+cs(graymap(ntone),ks+j)*cterm
cterm=cterm*conjg(cp(graymap(ntone)))
enddo
s2(i)=abs(csum)**2
s2(i)=abs(csum)
enddo
ipt=1+(ks-1)*2
if(nsym.eq.1) ibmax=1

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@ -275,12 +275,8 @@ contains
fb=min(4800,nfb)
endif
if(hmod.eq.1) then
if(ntrperiod.eq.15) minsync=1.15
if(ntrperiod.gt.15) minsync=1.25
elseif(hmod.gt.1) then
minsync=1.2
endif
if(ntrperiod.eq.15) minsync=1.15
! Get first approximation of candidate frequencies
call get_candidates_fst4(c_bigfft,nfft1,nsps,hmod,fs,fa,fb, &
@ -788,13 +784,13 @@ contains
iploc=ia+im(1)-1 !Index of CCF peak
pval=s2(iploc) !Peak value
if(pval.lt.minsync) exit
! do i=-3,+3 !Remove 0.9 of a model CCF at
! k=iploc+2*hmod*i !this frequency from s2()
! if(k.ge.ia .and. k.le.ib) then
! s2(k)=max(0.,s2(k)-0.9*pval*xdb(i))
! endif
! enddo
s2(max(1,iploc-2*hmod*3):min(nnw,iploc+2*hmod*3))=0.0
do i=-3,+3 !Remove 0.9 of a model CCF at
k=iploc+2*hmod*i !this frequency from s2()
if(k.ge.ia .and. k.le.ib) then
s2(k)=max(0.,s2(k)-0.9*pval*xdb(i))
endif
enddo
! s2(max(1,iploc-2*hmod*3):min(nnw,iploc+2*hmod*3))=0.0
ncand=ncand+1
candidates(ncand,1)=df2*iploc !Candidate frequency
candidates(ncand,2)=pval !Rough estimate of SNR