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68 lines
1.6 KiB
Fortran
68 lines
1.6 KiB
Fortran
program test_snr
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! Test an algorithm for measuring SNR of EME echoes.
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use wavhdr
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parameter (NMAX=27648) !27*1024
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parameter (NFFT=32768,NH=NFFT/2)
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parameter (NZ=4096)
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type(hdr) h !Header for the .wav file
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integer*2 id2(NMAX) !Buffer for Rx data
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complex c(0:NH)
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real x(NFFT)
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real s(8192)
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real sa(4096)
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real sb(4096)
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real red(4096)
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real blue(4096)
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character*80 infile
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equivalence (x,c)
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nargs=iargc()
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if(nargs.lt.1) then
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print*,'Usage: test_snr <infile>'
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go to 999
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endif
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call getarg(1,infile)
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i0=index(infile,'_')
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read(infile(1:i0-1),*) fspread0 !Generated Doppler spread
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read(infile(i0+1:i0+3),*) snrdb0 !Generated SNR
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open(10,file=trim(infile),status='old',access='stream')
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read(10) h
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npts=h%ndata/2
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npings=npts/NMAX
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nfsample=h%nsamrate
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df=12000.0/NFFT
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s=0.
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fac=1.0/NMAX
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do iping=1,npings
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read(10) id2(1:NMAX)
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x(1:NMAX)=fac*id2(1:NMAX)
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x(NMAX+1:)=0.
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call four2a(x,NFFT,1,-1,0)
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do i=1,8192 !Accumulate spectrum 0 - 3 kHz
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s(i)=s(i) + real(c(i))**2 + aimag(c(i))**2
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enddo
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enddo
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sa=s(2049:6144)
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sb=s(2049:6144)
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call echo_snr(sa,sb,fspread0,blue,red,snrdb,db_err,fpeak,snr_detect)
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nqual=min(10,int(snr_detect-4.0))
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write(*,1010) fspread0,snrdb0,snrdb,snrdb-snrdb0,db_err,fpeak, &
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snr_detect,nqual
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1010 format(5f6.1,2f7.1,i4)
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do i=1,8192
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write(12,1100) i*df,s(i)
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1100 format(f10.3,e15.6)
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enddo
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999 end program test_snr
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