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Various changes to JT65 decoding, all potentially temporary.

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1. Measure Doppler width by fitting a (modified) Lorentzian.
2. Don't call "slope" in sync65().
3. New definition of "sync1".
4. Get snr from sync1.


git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@6536 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
This commit is contained in:
Joe Taylor 2016-03-17 18:52:06 +00:00
parent 9f388b63dc
commit 533bb81220
8 changed files with 175 additions and 42 deletions
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2
CMakeLists.txt
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@ -309,6 +309,7 @@ set (wsjt_FSRCS
lib/fast9.f90
lib/fast_decode.f90
lib/fchisq.f90
lib/fchisq0.f90
lib/fchisq65.f90
lib/fftw3mod.f90
lib/fil3.f90
@ -362,6 +363,7 @@ set (wsjt_FSRCS
lib/jtmsk_decode.f90
lib/jtmsk_short.f90
lib/libration.f90
lib/lorentzian.f90
lib/lpf1.f90
lib/mixlpf.f90
lib/moondopjpl.f90

23
lib/fchisq0.f90 Normal file
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@ -0,0 +1,23 @@
real function fchisq0(y,npts,a)
real y(npts),a(4)
rewind 51
chisq = 0.
do i=1,npts
x=i
z=(x-a(3))/(0.5*a(4))
yfit=a(1)
if(abs(z).lt.3.0) then
d=1.0 + z*z
yfit=a(1) + a(2) * (1.0/d - 0.1)
endif
chisq=chisq + (y(i) - yfit)**2
! write(51,3001) i,y(i),yfit,y(i)-yfit
!3001 format(i5,3f10.4)
enddo
fchisq0=chisq
return
end function fchisq0

5
lib/fer65.f90
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@ -151,7 +151,10 @@ program fer65
dsnr=xsnr-snr
dfreq=xfreq-1500.0
if(ngood.eq.0) dsnr=0.
if(ngood.eq.0) then
dsnr=0.
dfreq=0.
endif
write(20,1100) snr,nsync,ngood,nbad,xsync,esync,dsnr,esnr, &
xdt,edt,dfreq,efreq,xdrift,edrift,xwidth,ewidth
1100 format(f5.1,2i6i4,2f6.1,f6.1,f5.1,f6.2,f5.2,6f5.1)

54
lib/jt65_decode.f90
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@ -124,6 +124,19 @@ contains
nfb=min(4000,nfqso+ntol)
thresh0=1.0
endif
df=12000.0/8192.0 !df = 1.465 Hz
if(single_decode) then
ia=max(1,nint(nfa/df)-100)
ib=min(NSZ,nint(nfb/df)+100)
nz=ib-ia+1
call lorentzian(savg(ia),nz,a)
baseline=a(1)
amp=a(2)
f0=(a(3)+ia-1)*df
width=a(4)*df
! write(*,3001) baseline,amp,f0,width
!3001 format(4f10.3)
endif
! robust = .false.: use float ccf. Only if ncand>50 fall back to robust (1-bit) ccf
! robust = .true. : use only robust (1-bit) ccf
@ -143,39 +156,7 @@ contains
! If a candidate was found within +/- ntol of nfqso, move it into ca(1).
call fqso_first(nfqso,ntol,ca,ncand)
df=12000.0/8192.0 !df = 1.465 Hz
width=0.
if(single_decode) then
ncand=1
smax=-1.e30
do i=151,NSZ-150
if(savg(i).gt.smax) then
smax=savg(i)
ipk=i
endif
! write(50,3001) i*df,savg(i)
!3001 format(2f12.3)
enddo
base=(sum(savg(ipk-149:ipk-50)) + sum(savg(ipk+51:ipk+150)))/200.0
stest=smax - 0.5*(smax-base)
ssum=savg(ipk)
do i=1,50
if(savg(ipk+i).lt.stest) exit
ssum=ssum + savg(ipk+i)
enddo
do i=1,50
if(savg(ipk-i).lt.stest) exit
ssum=ssum + savg(ipk-i)
enddo
ww=ssum/savg(ipk)
width=2
t=ww*ww - 5.67
if(t.gt.0.0) width=sqrt(t)
width=df*width
! print*,'Width:',width
endif
if(single_decode) ncand=1
nvec=ntrials
if(ncand.gt.75) then
! write(*,*) 'Pass ',ipass,' ncandidates too large ',ncand
@ -220,9 +201,10 @@ contains
nfreq=nint(freq+a(1))
ndrift=nint(2.0*a(2))
s2db=10.0*log10(sync2) - 35 !### empirical ###
if(width.gt.3) s2db=s2db + 2.1*sqrt(width-3.0) + 1.5 + &
0.11*(width-7.0) !### empirical^2 ###
! s2db=10.0*log10(sync2) - 35 !### empirical ###
! if(width.gt.3) s2db=s2db + 2.1*sqrt(width-3.0) + 1.5 + &
! 0.11*(width-7.0) !### empirical^2 ###
s2db=sync1 - 30.0
nsnr=nint(s2db)
if(nsnr.lt.-30) nsnr=-30
if(nsnr.gt.-1) nsnr=-1

4
lib/jt65_test.f90
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@ -58,8 +58,10 @@ contains
integer, intent(in) :: submode
integer, intent(in) :: aggression
integer nwidth
real t
nwidth=max(nint(width),2)
t=max(0.0,width*width-7.2)
nwidth=max(nint(sqrt(t)),2)
write(*,1010) utc,snr,dt,freq,decoded
1010 format(i4.4,i4,f5.1,i5,1x,'#',1x,a22)
write(13,1012) utc,nint(sync),snr,dt,freq,drift,nwidth, &

105
lib/lorentzian.f90 Normal file
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@ -0,0 +1,105 @@
subroutine lorentzian(y,npts,a)
! Input: y(npts); assume x(i)=i, i=1,npts
! Output: a(4)
! a(1) = baseline
! a(2) = amplitude
! a(3) = x0
! a(4) = width
real y(npts)
real a(4)
real deltaa(4)
real x(1000)
if(npts.gt.1000) stop 'Error in lorentzian'
a=0.
df=12000.0/8192.0 !df = 1.465 Hz
width=0.
ymax=-1.e30
do i=1,npts
if(y(i).gt.ymax) then
ymax=y(i)
ipk=i
endif
! write(50,3001) i,i*df,y(i)
!3001 format(i6,2f12.3)
enddo
! base=(sum(y(ipk-149:ipk-50)) + sum(y(ipk+51:ipk+150)))/200.0
base=(sum(y(1:20)) + sum(y(npts-19:npts)))/40.0
stest=ymax - 0.5*(ymax-base)
ssum=y(ipk)
do i=1,50
if(ipk+i.gt.npts) exit
if(y(ipk+i).lt.stest) exit
ssum=ssum + y(ipk+i)
enddo
do i=1,50
if(ipk-i.lt.1) exit
if(y(ipk-i).lt.stest) exit
ssum=ssum + y(ipk-i)
enddo
ww=ssum/y(ipk)
width=2
t=ww*ww - 5.67
if(t.gt.0.0) width=sqrt(t)
a(1)=base
a(2)=ymax-base
a(3)=ipk
a(4)=width
! Now find Lorentzian parameters
deltaa(1)=0.1
deltaa(2)=0.1
deltaa(3)=1.0
deltaa(4)=1.0
nterms=4
! Start the iteration
chisqr=0.
chisqr0=1.e6
do iter=1,5
do j=1,nterms
chisq1=fchisq0(y,npts,a)
fn=0.
delta=deltaa(j)
10 a(j)=a(j)+delta
chisq2=fchisq0(y,npts,a)
if(chisq2.eq.chisq1) go to 10
if(chisq2.gt.chisq1) then
delta=-delta !Reverse direction
a(j)=a(j)+delta
tmp=chisq1
chisq1=chisq2
chisq2=tmp
endif
20 fn=fn+1.0
a(j)=a(j)+delta
chisq3=fchisq0(y,npts,a)
if(chisq3.lt.chisq2) then
chisq1=chisq2
chisq2=chisq3
go to 20
endif
! Find minimum of parabola defined by last three points
delta=delta*(1./(1.+(chisq1-chisq2)/(chisq3-chisq2))+0.5)
a(j)=a(j)-delta
deltaa(j)=deltaa(j)*fn/3.
! write(*,4000) iter,j,a,chisq2
!4000 format(i1,i2,4f10.4,f11.3)
enddo
chisqr=fchisq0(y,npts,a)
! write(*,4000) 0,0,a,chisqr
if(chisqr/chisqr0.gt.0.99) go to 30
chisqr0=chisqr
enddo
30 ccfbest=ccfmax * (1378.125/fsample)**2
dtbest=dtmax
return
end subroutine lorentzian

2
lib/slope.f90
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@ -1,7 +1,7 @@
subroutine slope(y,npts,xpk)
! Remove best-fit slope from data in y(i). When fitting the straight line,
! ignore the peak around xpk +/- 2.
! ignore the peak around xpk +/- nhw
real y(npts)

22
lib/sync65.f90
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@ -31,7 +31,7 @@ subroutine sync65(ss,nfa,nfb,naggressive,ntol,nhsym,ca,ncand,nrobust)
do i=ia,ib
call xcor(ss,i,nhsym,nsym,lag1,lag2,ccfblue,ccf0,lagpk0,flip,fdot,nrobust)
! Remove best-fit slope from ccfblue and normalize so baseline rms=1.0
call slope(ccfblue(lag1),lag2-lag1+1,lagpk0-lag1+1.0)
! call slope(ccfblue(lag1),lag2-lag1+1,lagpk0-lag1+1.0)
ccfred(i)=ccfblue(lagpk0)
if(ccfred(i).gt.ccfmax) then
ccfmax=ccfred(i)
@ -43,6 +43,12 @@ subroutine sync65(ss,nfa,nfb,naggressive,ntol,nhsym,ca,ncand,nrobust)
ccfred(ia-1)=ccfred(ia)
ccfred(ib+1)=ccfred(ib)
! do i=1,NSZ
! ssum=sum(ss(1:322,i))/322.0
! write(61,3001) i*df,ccfred(i),ssum
! enddo
do i=ia,ib
freq=i*df
itry=0
@ -59,7 +65,7 @@ subroutine sync65(ss,nfa,nfb,naggressive,ntol,nhsym,ca,ncand,nrobust)
endif
if(itry.ne.0) then
call xcor(ss,i,nhsym,nsym,lag1,lag2,ccfblue,ccf0,lagpk,flip,fdot,nrobust)
call slope(ccfblue(lag1),lag2-lag1+1,lagpk-lag1+1.0)
! call slope(ccfblue(lag1),lag2-lag1+1,lagpk-lag1+1.0)
xlag=lagpk
if(lagpk.gt.lag1 .and. lagpk.lt.lag2) then
call peakup(ccfblue(lagpk-1),ccfmax,ccfblue(lagpk+1),dx2)
@ -70,10 +76,20 @@ subroutine sync65(ss,nfa,nfb,naggressive,ntol,nhsym,ca,ncand,nrobust)
ccfblue(lag2)=0.
ca(ncand)%freq=freq
ca(ncand)%dt=dtx
ca(ncand)%sync=ccfred(i)
! ca(ncand)%sync=ccfred(i)
ca(ncand)%sync=db(ccfred(i)) - 16.0
endif
if(ncand.eq.MAXCAND) return
enddo
! do i=1,NSZ
! write(52,3001) i*df,ccfred(i)
!3001 format(3f12.3)
! enddo
! do i=-10,58
! write(53,3002) i,i*2048.0/11025.0,ccfblue(i)
!3002 format(i6,2f12.3)
! enddo
return
end subroutine sync65