186 lines
5.2 KiB
Fortran
186 lines
5.2 KiB
Fortran
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program fsk4sim
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parameter (ND=60) !Data symbols: LDPC (120,60), r=1/2
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parameter (NN=ND) !Total symbols (60)
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parameter (NSPS=57600) !Samples per symbol at 12000 sps
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parameter (NZ=NSPS*NN) !Samples in waveform (3456000)
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character*8 arg
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complex c(0:NZ-1) !Complex waveform
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complex cr(0:NZ-1)
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complex cs(NSPS,NN)
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complex cps(0:3)
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complex ct(0:2*NN-1)
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complex z,w,zsum
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real r(0:NZ-1)
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real s(NSPS,NN)
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real savg(NSPS)
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real tmp(NN) !For generating random data
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real xnoise(0:NZ-1) !Generated random noise
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real ps(0:3)
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integer id(NN) !Encoded 2-bit data (values 0-3)
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integer id2(NN) !Recovered data
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equivalence (r,cr)
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nnn=0
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nargs=iargc()
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if(nargs.ne.6) then
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print*,'Usage: fsk8sim f0 delay(ms) fspread(Hz) nts iters snr(dB)'
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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,*) f0 !Low tone frequency
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call getarg(2,arg)
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read(arg,*) delay
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call getarg(3,arg)
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read(arg,*) fspread
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call getarg(4,arg)
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read(arg,*) nts
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call getarg(5,arg)
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read(arg,*) iters
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call getarg(6,arg)
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read(arg,*) snrdb
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twopi=8.d0*atan(1.d0)
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fs=12000.d0
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dt=1.0/fs
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ts=NSPS*dt
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baud=1.d0/ts
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txt=NZ*dt
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bandwidth_ratio=2500.0/6000.0
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write(*,1000) baud,5*baud,txt,delay,fspread,nts
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1000 format('Baud:',f6.3,' BW:',f5.1,' TxT:',f5.1,' Delay:',f5.2, &
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' fSpread:',f5.2,' nts:',i3/)
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write(*,1004)
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1004 format(' SNR Sym Bit SER BER Sym Bit SER BER'/59('-'))
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isna=-25
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isnb=-40
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if(snrdb.ne.0.0) then
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isna=nint(snrdb)
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isnb=isna
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endif
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do isnr=isna,isnb,-1
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snrdb=isnr
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sig=sqrt(2*bandwidth_ratio) * 10.0**(0.05*snrdb)
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if(snrdb.gt.90.0) sig=1.0
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nhard1=0
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nhard2=0
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nbit1=0
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nbit2=0
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nh2=0
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nb2=0
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do iter=1,iters
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nnn=nnn+1
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id=0
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call random_number(tmp)
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where(tmp.ge.0.25 .and. tmp.lt.0.50) id=1
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where(tmp.ge.0.50 .and. tmp.lt.0.75) id=2
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where(tmp.ge.0.75) id=3
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call genfsk4(id,f0,nts,c) !Generate the 4-FSK waveform
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call watterson(c,delay,fspread)
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if(sig.ne.1.0) c=sig*c !Scale to requested SNR
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if(snrdb.lt.90) then
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do i=0,NZ-1 !Generate gaussian noise
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xnoise(i)=gran()
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enddo
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endif
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r(0:NZ-1)=real(c(0:NZ-1)) + xnoise !Add noise to signal
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call snr2_wsprlf(r,freq,snr2500,width,1)
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write(*,3001) freq,snr2500,width
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3001 format(40x,3f10.3)
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df=12000.0/(2*NSPS)
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! i0=nint(f0/df)
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! i0=nint((1500.0+freq)/df)
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i0=nint((f0+freq)/df)
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call spec4(r,cs,s,savg)
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do j=1,NN
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nlo=0
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nhi=0
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ps=s(i0:i0+6*nts:2*nts,j)
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cps=cs(i0:i0+6*nts:2*nts,j)
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if(max(ps(1),ps(3)).ge.max(ps(0),ps(2))) nlo=1
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if(max(ps(2),ps(3)).ge.max(ps(0),ps(1))) nhi=1
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id2(j)=2*nhi+nlo
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z=cps(id2(j))
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ct(j-1)=z
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enddo
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nh1=count(id.ne.id2)
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nb1=count(iand(id,1).ne.iand(id2,1)) + count(iand(id,2).ne.iand(id2,2))
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ct(NN:)=0.
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call four2a(ct,2*NN,1,-1,1)
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df2=baud/(2*NN)
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ct=cshift(ct,NN)
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ppmax=0.
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dfpk=0.
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do i=0,2*NN-1
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f=(i-NN)*df2
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pp=real(ct(i))**2 + aimag(ct(i))**2
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if(pp.gt.ppmax) then
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ppmax=pp
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dfpk=f
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endif
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enddo
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zsum=0.
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do j=1,NN
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phi=(j-1)*twopi*dfpk*ts
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w=cmplx(cos(phi),sin(phi))
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cps=cs(i0:i0+6*nts:2*nts,j)*conjg(w)
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z=cps(id2(j))
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ct(j)=z
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zsum=zsum+z
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write(12,1042) j,id(j),id2(j),20*ps,atan2(aimag(z),real(z)), &
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atan2(aimag(zsum),real(zsum)),zsum
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1042 format(3i2,6f8.3,2f8.1)
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enddo
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phi0=atan2(aimag(zsum),real(zsum))
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zsum=0.
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do j=1,NN
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phi=(j-1)*twopi*dfpk*ts + phi0
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w=cmplx(cos(phi),sin(phi))
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nlo=0
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nhi=0
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cps=cs(i0:i0+6*nts:2*nts,j)*conjg(w)
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ps=real(cps)
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if(max(ps(1),ps(3)).ge.max(ps(0),ps(2))) nlo=1
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if(max(ps(2),ps(3)).ge.max(ps(0),ps(1))) nhi=1
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id2(j)=2*nhi+nlo
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z=cps(id2(j))
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ct(j)=z
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zsum=zsum+z
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enddo
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nh2=count(id.ne.id2)
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nb2=count(iand(id,1).ne.iand(id2,1)) + count(iand(id,2).ne.iand(id2,2))
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nhard1=nhard1+nh1
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nhard2=nhard2+nh2
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nbit1=nbit1+nb1
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nbit2=nbit2+nb2
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fdiff=1500.0+freq - f0
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write(13,1040) snrdb,snr2500,f0,fdiff,width,nh1,nb1,nh2,nb2
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1040 format(2f7.1,f9.2,f7.2,f6.1,2(i8,i6))
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40 continue
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enddo
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ser1=float(nhard1)/(NN*iters)
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ser2=float(nhard2)/(NN*iters)
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ber1=float(nbit1)/(2*NN*iters)
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ber2=float(nbit2)/(2*NN*iters)
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write(*,1050) snrdb,nhard1,nbit1,ser1,ber1,nhard2,nbit2,ser2,ber2
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write(14,1050) snrdb,nhard1,nbit1,ser1,ber1,nhard2,nbit2,ser2,ber2
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1050 format(f6.1,2(2i5,2f8.4))
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enddo
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write(*,1060) NN*iters,2*NN*iters
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1060 format(59('-')/'Max: ',2i5)
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999 end program fsk4sim
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