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https://github.com/saitohirga/WSJT-X.git
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111 lines
3.0 KiB
FortranFixed
111 lines
3.0 KiB
FortranFixed
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subroutine avemsg6m(s2db,nz,nslim,NFixLen,cfile6,lcum,
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+ f0,lumsg,npkept)
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C Attempts to find message length and then decodes an average message.
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real s2db(0:43,nz)
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real s2dc(0:43,22)
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real wgt(22)
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real acf(0:430)
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logical lcum
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character*43 pua
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character*6 cfile6
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character*22 avemsg,blanks
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data pua/'0123456789., /#?$ABCDEFGHIJKLMNOPQRSTUVWXYZ'/
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data blanks/' '/
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data twopi/6.283185307/
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data offset/20.6/
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C Adjustable sig limit, depending on length of data to average.
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nslim2=nslim - 9 + 4.0*log10(624.0/nz) !### +10 was here
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k=0
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sum=0.
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nsum=0
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do j=1,nz
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if(mod(j,3).eq.1) then
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sum=sum+s2db(0,j) !Measure avg sig strength for sync tone
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nsum=nsum+1
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else
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k=k+1
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call move(s2db(0,j),s2db(0,k),44) !Save data spectra
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endif
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enddo
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sig=sum/nsum !Signal strength estimate
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nsig=nint(db(sig)-offset)
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C Most of the time in this routine is in this loop.
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kz=k
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do lag=0,kz-1
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sum=0.
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do j=1,kz-lag
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do i=0,43
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sum=sum+s2db(i,j)*s2db(i,j+lag)
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enddo
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enddo
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acf(lag)=sum
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enddo
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acf0=acf(0)
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do lag=0,kz-1
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acf(lag)=acf(lag)/acf0
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enddo
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lmsg1=NFixLen/256
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lmsg2=NFixLen-256*lmsg1
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if(mod(lmsg1,2).eq.1) lmsg1=lmsg1+1
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if(mod(lmsg2,2).eq.1) lmsg2=lmsg2+1
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smax=-1.e9
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do ip=4,22,2 !Compute periodogram for allowed msg periods
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if(NFixLen.ne.0 .and. ip.ne.4 .and. ip.ne.lmsg1
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+ .and. ip.ne.lmsg2) go to 5
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f=1.0/ip
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s=0.
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do lag=0,kz-1
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s=s+acf(lag)*cos(twopi*f*lag)
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enddo
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if(s.gt.smax) then
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smax=s
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msglen=ip !Save best message length
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endif
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5 enddo
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C Average the symbols from s2db into s2dc.
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call zero(s2dc,44*22)
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call zero(wgt,22)
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do j=1,kz
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k=mod(j-1,msglen)+1
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call add(s2db(0,j),s2dc(0,k),s2dc(0,k),44)
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wgt(k)=wgt(k)+1.0
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enddo
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do j=1,msglen !Hard-decode the avg msg,
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smax=-1.e9 !picking max bin for each char
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do i=1,43
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s2dc(i,j)=s2dc(i,j)/wgt(j)
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if(s2dc(i,j).gt.smax) then
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smax=s2dc(i,j)
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ipk=i
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endif
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enddo
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k=mod(ipk,3)
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i=ipk
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avemsg(j:j)=pua(i:i)
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enddo
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ndf0=nint(f0-1076.66)
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do i=1,msglen
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if(avemsg(i:i).eq.' ') goto 10
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enddo
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go to 20
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10 avemsg=avemsg(i+1:msglen)//avemsg(1:i)
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20 if(nsig.gt.nslim2) then
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npkept=npkept+1
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avemsg=avemsg(1:msglen)//blanks
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write(lumsg,1020) cfile6,nsig,ndf0,avemsg,msglen
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if(lcum) write(21,1020) cfile6,nsig,ndf0,avemsg,msglen
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1020 format(a6,8x,i6,i5,7x,a22,19x,'*',i4)
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endif
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return
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end
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