mirror of https://github.com/saitohirga/WSJT-X.git
234 lines
5.7 KiB
Fortran
234 lines
5.7 KiB
Fortran
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program fsk4sim
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use wavhdr
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parameter (NR=4) !Ramp up, ramp down
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parameter (NS=12) !Sync symbols (2 @ Costas 4x4)
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parameter (ND=84) !Data symbols: LDPC (168,84), r=1/2
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parameter (NN=NR+NS+ND) !Total symbols (100)
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parameter (NSPS=2688) !Samples per symbol at 12000 sps
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parameter (NZ=NSPS*NN) !Samples in waveform (258048)
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parameter (NFFT=512*1024)
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parameter (NSYNC=NS*NSPS)
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type(hdr) header !Header for .wav file
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character*8 arg
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complex c(0:NFFT-1) !Complex waveform
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complex cf(0:NFFT-1)
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complex cs(0:NSYNC-1)
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complex ct(0:NSPS-1)
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complex csync(0:NSYNC-1)
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complex z
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real*8 twopi,dt,fs,baud,f0,dphi,phi
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real tmp(NN) !For generating random data
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real s(0:NFFT-1)
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! real s2(0:NFFT-1)
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real xnoise(NZ) !Generated random noise
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real ps(0:3)
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integer*2 iwave(NZ) !Generated waveform
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integer id(NN) !Encoded 2-bit data (values 0-3)
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integer icos4(4) !4x4 Costas array
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data icos4/0,1,3,2/
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nargs=iargc()
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if(nargs.ne.3) then
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print*,'Usage: fsk8sim f0 iters snr'
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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,*) iters
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call getarg(3,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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isna=-20
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isnb=-30
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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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bandwidth_ratio=2500.0/6000.0
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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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header=default_header(12000,NZ)
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open(10,file='000000_0001.wav',access='stream',status='unknown')
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nsyncerr=0
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nharderr=0
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nbiterr=0
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do iter=1,iters
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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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id(1:2)=icos4(3:4) !Ramp up
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id(45:48)=icos4 !Costas sync
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id(49:52)=icos4 !Costas sync
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id(53:56)=icos4 !Costas sync
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id(NN-1:NN)=icos4(1:2) !Ramp down
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! Generate sync waveform
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phi=0.d0
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k=-1
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do j=45,56
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dphi=twopi*(id(j)*baud)*dt
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do i=1,NSPS
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k=k+1
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phi=phi+dphi
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if(phi.gt.twopi) phi=phi-twopi
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xphi=phi
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csync(k)=cmplx(cos(xphi),-sin(xphi))
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enddo
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enddo
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! Generate the 4-FSK waveform
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x=0.
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c=0.
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phi=0.d0
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k=-1
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u=0.5
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do j=1,NN
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dphi=twopi*(f0 + id(j)*baud)*dt
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do i=1,NSPS
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k=k+1
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phi=phi+dphi
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if(phi.gt.twopi) phi=phi-twopi
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xphi=phi
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c(k)=cmplx(cos(xphi),sin(xphi))
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enddo
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enddo
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if(sig.ne.1.0) c=sig*c
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nh=NFFT/2
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df=12000.0/NFFT
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s=0.
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cf=c
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call four2a(cf,NFFT,1,-1,1) !Transform to frequency domain
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flo=f0-baud
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fhi=f0+4*baud
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do i=0,NFFT-1 !Remove spectral sidelobes
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f=i*df
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if(i.gt.nh) f=(i-nfft)*df
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if(f.le.flo .or. f.ge.fhi) cf(i)=0.
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s(i)=s(i) + real(cf(i))**2 + aimag(cf(i))**2
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enddo
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! s2=cshift(s,nh)
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! s2=s2/maxval(s2)
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! do i=0,NFFT-1
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! f=(i-nh)*df
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! write(13,1000) f,s2(i),10.0*log10(s2(i)+1.e-12)
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!1000 format(3f12.3)
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! enddo
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c=cf
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call four2a(c,NFFT,1,1,1) !Transform back to time domain
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c=c/nfft
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xnoise=0.
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if(snrdb.lt.90) then
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a=1.0/sqrt(2.0)
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do i=0,NZ-1
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xx=a*gran()
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yy=a*gran()
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c(i)=c(i) + cmplx(xx,yy) !Scale signal and add noise
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enddo
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endif
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fac=32767.0
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rms=100.0
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if(snrdb.ge.90.0) iwave(1:NZ)=nint(fac*aimag(c(0:NZ-1)))
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if(snrdb.lt.90.0) iwave(1:NZ)=nint(rms*aimag(c(0:NZ-1)))
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call set_wsjtx_wav_params(14.0,'JT65 ',1,30,iwave)
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write(10) header,iwave !Save the .wav file
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! do i=0,NZ-1
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! a=abs(c(i))
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! j=mod(i,NSPS)
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! write(14,1010) i*dt/ts,c(i),a
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!1010 format(4f12.6)
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! enddo
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ppmax=0.
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fpk=-99.
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xdt=-99.
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do j4=-40,40
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ia=(44+0.25*j4)*NSPS
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ib=ia+NSYNC-1
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cs=csync*c(ia:ib)
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call four2a(cs,NSYNC,1,-1,1) !Transform to frequency domain
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df1=12000.0/NSYNC
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fac=1.e-6
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do i=0,NSYNC/2
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pp=fac*(real(cs(i))**2 + aimag(cs(i))**2)
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if(pp.gt.ppmax) then
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fpk=i*df1
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xdt=0.25*j4*ts
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ppmax=pp
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endif
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! if(j4.eq.0) then
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! f=i*df1
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! write(16,1030) f,pp,10.0*log10(pp)
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!1030 format(3f15.3)
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! endif
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enddo
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enddo
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if(xdt.ne.0.0 .or. fpk.ne.1500.0) nsyncerr=nsyncerr+1
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ipk=0
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do j=1,NN
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ia=(j-1)*NSPS + 1
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ib=ia+NSPS
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pmax=0.
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do i=0,3
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f=fpk + i*baud
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call tweak1(c(ia:ib),NSPS,-f,ct)
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z=sum(ct)
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ps(i)=1.e-3*(real(z)**2 + aimag(z)**2)
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if(ps(i).gt.pmax) then
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ipk=i
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pmax=ps(i)
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endif
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enddo
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nlo=0
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nhi=0
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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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! if(ps(1)+ps(3).ge.ps(0)+ps(2)) nlo=1
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! if(ps(2)+ps(3).ge.ps(0)+ps(1)) nhi=1
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if(nlo.ne.iand(id(j),1)) nbiterr=nbiterr+1
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if(nhi.ne.iand(id(j)/2,1)) nbiterr=nbiterr+1
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if(ipk.ne.id(j)) nharderr=nharderr+1
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write(17,1040) j,ps,ipk,id(j),2*nhi+nlo,nhi,nlo,nbiterr
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1040 format(i3,4f12.1,6i4)
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enddo
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enddo
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fsyncerr=float(nsyncerr)/iters
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ser=float(nharderr)/(NN*iters)
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ber=float(nbiterr)/(2*NN*iters)
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write(*,1050) snrdb,nsyncerr,nharderr,nbiterr,fsyncerr,ser,ber
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write(18,1050) snrdb,nsyncerr,nharderr,nbiterr,fsyncerr,ser,ber
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1050 format(f6.1,3i6,3f10.6)
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enddo
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999 end program fsk4sim
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