mirror of https://github.com/saitohirga/WSJT-X.git
159 lines
3.9 KiB
Fortran
159 lines
3.9 KiB
Fortran
subroutine genjtms3(msg28,iwave,nwave)
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!subroutine genjtms3(msg28,iwave,cwave,isrch,nwave)
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! Generate a JTMS3 wavefile.
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parameter (NMAX=30*48000) !Max length of wave file
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integer*2 iwave(NMAX) !Generated wave file
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complex cwave(NMAX) !Alternative for searchms
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character*28 msg28 !User message
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character*29 msg
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character cc*64
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integer sentsym(203) !Transmitted symbols (0/1)
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real sentsam(4872) !Transmitted waveform
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real*8 dt,phi,f0,dphi,pi,twopi,samfac
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real p(0:420)
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real carrier(4872)
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real dat(4872),bb(4872),wave(4872)
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complex cdat(0:2436)
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logical first
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integer np(9)
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data np/5,7,9,11,13,17,19,23,29/ !Permissible message lengths
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! 1 2 3 4 5 6
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! 0123456789012345678901234567890123456789012345678901234567890123
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data cc/'0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ./?- _ @'/
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data samfac/1.d0/,first/.true./
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equivalence (dat,cdat)
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save
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sinc(x)=sin(pi*x)/(pi*x)
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if(first) then
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pi=4.d0*atan(1.d0)
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twopi=2.d0*pi
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x=0.
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dx=1.0/24.0
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width=3.0
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do i=1,420 !Generate the BPSK pulse shape
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x=x+dx
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fac=0.0
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if(x/width.lt.0.5*pi) then
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fac=(cos(x/width))**2
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ipz=i
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endif
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p(i)=fac*sinc(x)
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enddo
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p(0)=1.0
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f0=10000.d0/7.d0
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dt=1.d0/48000.d0
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dphi=twopi*f0*dt
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phi=0.d0
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do i=1,4872 !Generate the carrier
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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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carrier(i)=sin(xphi)
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enddo
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first=.false.
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endif
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msg=msg28//' ' !Extend to 29 characters
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do i=28,1,-1 !Find user's message length
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if(msg(i:i).ne.' ') go to 1
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enddo
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1 iz=i+1 !Add one for space at EOM
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msglen=iz
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if(isrch.ne.0) go to 3
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do i=1,9
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if(np(i).ge.iz) go to 2
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enddo
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i=8
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2 msglen=np(i)
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! Convert message to a bit sequence, 7 bits per character (6 + even parity)
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3 sentsym=0
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k=0
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do j=1,msglen
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if(msg(j:j).eq.' ') then
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i=58
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go to 5
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else
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do i=1,64
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if(msg(j:j).eq.cc(i:i)) go to 5
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enddo
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endif
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5 m=0
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do n=5,0,-1 !Each character gets 6 bits
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k=k+1
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sentsym(k)=iand(1,ishft(i-1,-n))
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m=m+sentsym(k)
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enddo
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k=k+1
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sentsym(k)=iand(m,1) !Insert bit for even parity
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enddo
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nsym=7*msglen !# symbols in message
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nsam=24*nsym !# samples in message
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bb(1:nsam)=0.
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do j=1,nsym
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fac=1.0
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if(sentsym(j).eq.0) fac=-1.0
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k0=24*j - 23
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do i=0,ipz
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k=k0+i
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if(k.gt.nsam) k=k-nsam
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bb(k)=bb(k) + fac*p(i)
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if(i.gt.0) then
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k=k0-i
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if(k.lt.1) k=k+nsam
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bb(k)=bb(k) + fac*p(i)
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endif
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enddo
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enddo
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sq=0.
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wmax=0.
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do i=1,nsam
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wave(i)=carrier(i)*bb(i)
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sq=sq + wave(i)**2
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wmax=max(wmax,abs(wave(i)))
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! write(15,3002) i*dt,bb(i),wave(i)
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!3002 format(f12.6,2f12.3)
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enddo
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rms=sqrt(sq/nsam)
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! print*,rms,wmax,wmax/rms
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fac=32767.0/wmax
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iwave(1:nsam)=fac*wave(1:nsam)
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! nwave=nsam
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nblk=30*48000/nsam
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do n=2,nblk
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i0=(n-1)*nsam
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iwave(i0+1:i0+nsam)=iwave(1:nsam)
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enddo
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nwave=i0+nsam
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! Compute the spectrum
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! nfft=nsam
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! df=48000.0/nfft
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! ib=4000.0/df
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! fac=10.0/nfft
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! dat(1:nfft)=fac*bb(1:nfft)
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! call four2a(dat,nfft,1,-1,0)
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! do i=0,ib
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! sq=real(cdat(i))**2 + aimag(cdat(i))**2
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! write(14,3010) i*df,sq,10.0*log10(sq)
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!3010 format(3f12.3)
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! enddo
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! if(isrch.eq.0) iwave(k+1:)=0
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! nwave=k
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return
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end subroutine genjtms3
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