mirror of https://github.com/saitohirga/WSJT-X.git
147 lines
3.9 KiB
Fortran
147 lines
3.9 KiB
Fortran
subroutine sync4(dat,jz,ntol,nfqso,mode,mode4,minwidth,dtx,dfx,snrx, &
|
|
snrsync,flip,width)
|
|
|
|
! Synchronizes JT4 data, finding the best-fit DT and DF.
|
|
|
|
parameter (NFFTMAX=2520) !Max length of FFTs
|
|
parameter (NHMAX=NFFTMAX/2) !Max length of power spectra
|
|
parameter (NSMAX=525) !Max number of half-symbol steps
|
|
integer ntol !Range of DF search
|
|
real dat(jz)
|
|
real s2(NHMAX,NSMAX) !2d spectrum, stepped by half-symbols
|
|
real ccfblue(-5:540) !CCF with pseudorandom sequence
|
|
real ccfred(NHMAX) !Peak of ccfblue, as function of freq
|
|
real red(NHMAX) !Peak of ccfblue, as function of freq
|
|
integer ipk1(1)
|
|
integer nch(7)
|
|
logical savered
|
|
equivalence (ipk1,ipk1a)
|
|
data nch/1,2,4,9,18,36,72/
|
|
save
|
|
|
|
! Do FFTs of twice symbol length, stepped by half symbols. Note that
|
|
! we have already downsampled the data by factor of 2.
|
|
nsym=207
|
|
nfft=2520
|
|
nh=nfft/2
|
|
nq=nfft/4
|
|
nsteps=jz/nq - 1
|
|
df=0.5*11025.0/nfft
|
|
ftop=nfqso + 7*mode4*df
|
|
if(ftop.gt.11025.0/4.0) then
|
|
print*,'*** Rx Freq is set too high for this submode ***'
|
|
go to 900
|
|
endif
|
|
|
|
if(mode.eq.-999) width=0. !Silence compiler warning
|
|
|
|
do j=1,nsteps !Compute spectrum for each step, get average
|
|
k=(j-1)*nq + 1
|
|
call ps4(dat(k),nfft,s2(1,j))
|
|
enddo
|
|
|
|
! Set freq and lag ranges
|
|
ia=(nfqso-ntol)/df !Index of lowest tone, bottom of search range
|
|
ib=(nfqso+ntol)/df !Index of lowest tone, top of search range
|
|
iamin=nint(100.0/df)
|
|
if(ia.lt.iamin) ia=iamin
|
|
ibmax=nint(2700.0/df) - 6*mode4
|
|
if(ib.gt.ibmax) ib=ibmax
|
|
|
|
lag1=-5
|
|
lag2=59
|
|
syncbest=-1.e30
|
|
snrx=-26.0
|
|
ccfred=0.
|
|
red=0.
|
|
i0=nint(nfqso/df)
|
|
|
|
do ich=minwidth,7 !Find best width
|
|
kz=nch(ich)/2
|
|
savered=.false.
|
|
iaa=ia+kz
|
|
ibb=ib-kz
|
|
do i=iaa,ibb !Find best frequency channel for CCF
|
|
call xcor4(s2,i,nsteps,nsym,lag1,lag2,ich,mode4,ccfblue,ccf0, &
|
|
lagpk0,flip)
|
|
ccfred(i)=ccf0
|
|
|
|
! Find rms of the CCF, without main peak
|
|
call slope(ccfblue(lag1),lag2-lag1+1,lagpk0-lag1+1.0)
|
|
sync=abs(ccfblue(lagpk0))
|
|
! write(*,3000) ich,i,i*df,ccf0,sync,syncbest
|
|
!3000 format(2i5,4f12.3)
|
|
|
|
! Find best sync value
|
|
if(sync.gt.syncbest*1.03) then
|
|
ipk=i
|
|
lagpk=lagpk0
|
|
ichpk=ich
|
|
syncbest=sync
|
|
savered=.true.
|
|
endif
|
|
enddo
|
|
if(savered) red=ccfred
|
|
enddo
|
|
if(syncbest.lt.-1.e29) go to 900
|
|
ccfred=red
|
|
call pctile(ccfred(ia:ib),ib-ia+1,45,base)
|
|
ccfred=ccfred-base
|
|
|
|
dfx=ipk*df
|
|
|
|
! Peak up in time, at best whole-channel frequency
|
|
call xcor4(s2,ipk,nsteps,nsym,lag1,lag2,ichpk,mode4,ccfblue,ccfmax, &
|
|
lagpk,flip)
|
|
xlag=lagpk
|
|
if(lagpk.gt.lag1 .and. lagpk.lt.lag2) then
|
|
call peakup(ccfblue(lagpk-1),ccfmax,ccfblue(lagpk+1),dx2)
|
|
xlag=lagpk+dx2
|
|
endif
|
|
|
|
! Find rms of the CCF, without the main peak
|
|
call slope(ccfblue(lag1),lag2-lag1+1,xlag-lag1+1.0)
|
|
sq=0.
|
|
nsq=0
|
|
do lag=lag1,lag2
|
|
if(abs(lag-xlag).gt.2.0) then
|
|
sq=sq+ccfblue(lag)**2
|
|
nsq=nsq+1
|
|
endif
|
|
enddo
|
|
rms=sqrt(sq/nsq)
|
|
snrsync=max(0.0,db(abs(ccfblue(lagpk)/rms - 1.0)) - 4.5)
|
|
dt=2.0/11025.0
|
|
istart=xlag*nq
|
|
dtx=istart*dt
|
|
|
|
ipk1=maxloc(ccfred)
|
|
ccf10=0.5*maxval(ccfred)
|
|
do i=ipk1a,ia,-1
|
|
if(ccfred(i).le.ccf10) exit
|
|
enddo
|
|
i1=i
|
|
do i=ipk1a,ib
|
|
if(ccfred(i).le.ccf10) exit
|
|
enddo
|
|
nw=i-i1
|
|
width=nw*df
|
|
|
|
sq=0.
|
|
ns=0
|
|
iaa=max(ipk1a-10*nw,ia)
|
|
ibb=min(ipk1a+10*nw,ib)
|
|
jmax=2*mode4/3
|
|
do i=iaa,ibb
|
|
j=abs(i-ipk1a)
|
|
if(j.gt.nw .and. j.lt.jmax) then
|
|
sq=sq + ccfred(j)*ccfred(j)
|
|
ns=ns+1
|
|
endif
|
|
enddo
|
|
rms=sqrt(sq/ns)
|
|
snrx=10.0*log10(ccfred(ipk1a)/rms) - 41.2
|
|
|
|
900 return
|
|
end subroutine sync4
|