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100 lines
2.7 KiB
Fortran
100 lines
2.7 KiB
Fortran
subroutine avecho(id2,ndop,nfrit,nauto,nqual,f1,xlevel,snrdb,db_err, &
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dfreq,width,bDiskData)
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integer TXLENGTH
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parameter (TXLENGTH=27648) !27*1024
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parameter (NFFT=32768,NH=NFFT/2)
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parameter (NZ=4096)
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integer*2 id2(34560) !Buffer for Rx data
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real sa(NZ) !Avg spectrum relative to initial Doppler echo freq
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real sb(NZ) !Avg spectrum with Dither and changing Doppler removed
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integer nsum !Number of integrations
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real dop0 !Doppler shift for initial integration (Hz)
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real dop !Doppler shift for current integration (Hz)
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real s(8192)
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real x(NFFT)
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integer ipkv(1)
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logical ex
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logical*1 bDiskData
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complex c(0:NH)
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equivalence (x,c),(ipk,ipkv)
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common/echocom/nclearave,nsum,blue(NZ),red(NZ)
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common/echocom2/fspread_self,fspread_dx
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save dop0,sa,sb
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fspread=fspread_dx !### Use the predicted Doppler spread ###
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if(bDiskData) fspread=width
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if(nauto.eq.1) fspread=fspread_self
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inquire(file='fspread.txt',exist=ex)
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if(ex) then
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open(39,file='fspread.txt',status='old')
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read(39,*) fspread
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close(39)
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endif
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fspread=min(max(0.04,fspread),700.0)
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width=fspread
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dop=ndop
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sq=0.
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do i=1,TXLENGTH
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x(i)=id2(i)
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sq=sq + x(i)*x(i)
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enddo
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xlevel=10.0*log10(sq/TXLENGTH)
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if(nclearave.ne.0) nsum=0
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if(nsum.eq.0) then
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dop0=dop !Remember the initial Doppler
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sa=0. !Clear the average arrays
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sb=0.
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endif
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x(TXLENGTH+1:)=0.
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x=x/TXLENGTH
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call four2a(x,NFFT,1,-1,0)
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df=12000.0/NFFT
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do i=1,8192 !Get spectrum 0 - 3 kHz
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s(i)=real(c(i))**2 + aimag(c(i))**2
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enddo
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fnominal=1500.0 !Nominal audio frequency w/o doppler or dither
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ia=nint((fnominal+dop0-nfrit)/df)
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ib=nint((f1+dop-nfrit)/df)
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if(ia.lt.2048 .or. ib.lt.2048 .or. ia.gt.6144 .or. ib.gt.6144) then
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snrdb=0.
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db_err=0.
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dfreq=0.
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go to 900
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endif
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nsum=nsum+1
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do i=1,NZ
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sa(i)=sa(i) + s(ia+i-2048) !Center at initial doppler freq
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sb(i)=sb(i) + s(ib+i-2048) !Center at expected echo freq
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enddo
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call echo_snr(sa,sb,fspread,blue,red,snrdb,db_err,dfreq,snr_detect)
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nqual=snr_detect-2
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if(nqual.lt.0) nqual=0
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if(nqual.gt.10) nqual=10
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! Scale for plotting
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redmax=maxval(red)
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fac=10.0/max(redmax,10.0)
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blue=fac*blue
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red=fac*red
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nsmo=max(0.0,0.25*width/df)
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do i=1,nsmo
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call smo121(red,NZ)
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call smo121(blue,NZ)
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enddo
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ia=200.0/df
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ib=400.0/df
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call pctile(red(ia:ib),ib-ia+1,50,bred)
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red=red-bred
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call pctile(blue(ia:ib),ib-ia+1,50,bblue)
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blue=blue-bblue
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900 call sleep_msec(10) !Avoid the "blue Decode button" syndrome
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return
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end subroutine avecho
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