91 lines
1.9 KiB
Fortran
91 lines
1.9 KiB
Fortran
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program genmet
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! Generate metric table for M-FSK modulation.
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character*12 arg
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real*4 r(0:255)
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integer hist(2,-128:128)
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data hist/514*0/,idum/-1/
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lim(x)=min(127,max(-128,nint(scale*x)))
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nargs=iargc()
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if(nargs.ne.5) then
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print*,'Usage: genmet ncoh nadd m0 snr iters'
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go to 999
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endif
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call getarg(1,arg)
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read(arg,*) ncoh
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call getarg(2,arg)
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read(arg,*) nadd
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call getarg(3,arg)
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read(arg,*) m0
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call getarg(4,arg)
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read(arg,*) snr
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call getarg(5,arg)
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read(arg,*) iters
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ntones=2**m0
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xm0=m0
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scale=5.0
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fac=sqrt(1.0/nadd)
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s=sqrt(10.0**(0.1*snr))
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hist=0
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nerr=0
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call sgran()
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do iter=1,iters
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do i=0,ntones-1
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r(i)=0.
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do n=1,nadd
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x1=0.707*gran()
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y1=0.707*gran()
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if(i.eq.0) x1=x1+s
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if(ncoh.eq.0) r(i)=r(i) + x1*x1 + y1*y1
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if(ncoh.ne.0) r(i)=r(i) + x1
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enddo
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r(i)=fac*r(i)
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enddo
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do m=0,m0-1
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n=2**m
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r1=0.
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r2=0.
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do i=0,ntones-1
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if(iand(i,n).ne.0) r1=max(r1,r(i))
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if(iand(i,n).eq.0) r2=max(r2,r(i))
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enddo
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don=r2-r1
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doff=r1-r2
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if(don.lt.0.0) nerr=nerr+1
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j1=lim(doff)
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hist(1,j1)=hist(1,j1)+1
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j2=lim(don)
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hist(2,j2)=hist(2,j2)+1
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enddo
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enddo
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do i=-128,127
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write(13,1010) i/scale,hist(1,i)/(xm0*iters),hist(2,i)/(xm0*iters)
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1010 format(f8.3,2f12.9)
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enddo
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ber=nerr/(xm0*iters)
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write(*,1020) nadd,m0,snr,ber
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1020 format('nadd:',i3,' m0:',i2,' snr: 'f5.1,' BER:',f8.3)
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xln2=log(2.0)
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do i=-128,127
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p1=hist(2,i)/(xm0*iters)
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p0=hist(1,i)/(xm0*iters)
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if(p0+p1.eq.0.0 .and. i.lt.0) p0=1.e-6
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if(p0+p1.eq.0.0 .and. i.gt.0) p1=1.e-6
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xlhd0=log(max(0.001,2.0*p0/(p0+p1)))/xln2
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xlhd1=log(max(0.001,2.0*p1/(p0+p1)))/xln2
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write(14,1012) i/scale,xlhd0,xlhd1,p0/(p0+p1),p1/(p0+p1)
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1012 format(f7.1,2f8.3,2f9.6)
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enddo
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999 end program genmet
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