program t1 parameter (NSPM=1404) complex csig(0:NSPM-1) complex c(0:NSPM-1) complex cnoise(0:NSPM-1) complex cd(0:11,0:3) complex z,zmax integer itone(234) real r(234) real ss(0:3) character*12 arg nargs=iargc() if(nargs.ne.3) then print*,'Usage: t1 nsymtest snrdb iters' go to 999 endif call getarg(1,arg) read(arg,*) nsymtest call getarg(2,arg) read(arg,*) snrdb call getarg(3,arg) read(arg,*) iters call random_number(r) itone=0 where(r.gt.0.5) itone=1 twopi=8.0*atan(1.0) fmid=1500.0 f0=fmid-500. f1=fmid+500. dt=1.0/12000.0 phi=0. do n=0,3 k=-1 dphi=twopi*f0*dt if(n.ge.2) dphi=twopi*f1*dt do i=0,5 k=k+1 phi=phi+dphi if(phi.gt.twopi) phi=phi-twopi cd(k,n)=cmplx(cos(phi),sin(phi)) enddo dphi=twopi*f0*dt if(mod(n,2).eq.1) dphi=twopi*f1*dt do i=6,11 k=k+1 phi=phi+dphi if(phi.gt.twopi) phi=phi-twopi cd(k,n)=cmplx(cos(phi),sin(phi)) enddo enddo ! do k=0,11 ! write(13,1000) k,cd(k,0:3) !1000 format(i4,8f9.3) !enddo ! Generate signal waveform k=-1 phi=0. do j=1,234 dphi=twopi*f0*dt if(itone(j).eq.1) dphi=twopi*f1*dt do i=1,6 k=k+1 phi=phi+dphi if(phi.gt.twopi) phi=phi-twopi csig(k)=cmplx(cos(phi),sin(phi)) ! write(14,1000) k,csig(k) enddo enddo write(*,1010) 1010 format(' S/N (S+N)/N BER'/'----------------------') isnra=10 isnrb=-3 nsyms=234 do isnr=isnra,isnrb,-1 snr=10.0**(0.1*isnr) if(snrdb.ne.0.0) snr=10.0**(0.1*snrdb) fac=1.0/sqrt(snr) nsumerr=0 do iter=1,iters do i=0,NSPM-1 x=gran() y=gran() cnoise(i)=cmplx(x,y) enddo c=csig + fac*cnoise nerr=0 n1=2 nstep=2 iz=5 if(nsymtest.eq.2) then n1=3 nstep=1 iz=11 endif do j=1,nsyms smax=0. do n=0,n1,nstep s=0. k=6*(j-1) do i=0,iz s=s + aimag(c(k+i))*aimag(cd(i,n)) enddo ss(n)=s if(abs(s).gt.abs(smax)) then smax=s npk=n endif enddo sym=max(abs(ss(2)),abs(ss(3))) - max(abs(ss(0)),abs(ss(1))) ! ibit=npk/2 ibit=0 if(sym.ge.0.0) ibit=1 if(ibit.ne.itone(j)) nerr=nerr+1 enddo nsumerr=nsumerr+nerr enddo write(*,1020) 10.0*log10(snr),10.0*log10(snr+1.0), & float(nsumerr)/(nsyms*iters) 1020 format(f5.1,f7.1,f9.3) if(snrdb.ne.0.0) exit enddo 999 end program t1