mirror of
https://github.com/saitohirga/WSJT-X.git
synced 2024-10-05 03:26:53 -04:00
04c4b99a53
the JTMS of WSJT9. Modulation changed to BPSK, speed increased from 1378.125 to 2000 baud. git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/jtms3@2505 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
186 lines
4.6 KiB
Fortran
186 lines
4.6 KiB
Fortran
subroutine specjtms(k)
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! Starting code for a JTMS3 decoder.
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parameter (NSMAX=30*48000)
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parameter (NFFT=16384,NH=NFFT/2)
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character*22 decoded
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character*72 c72
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integer*2 id
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real x(NFFT),w(NFFT)
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real p(24)
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real rsent(258),softsym(683),sym2(258)
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integer nsum(24)
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complex cx(NFFT),cx2(NFFT),cx0(NFFT)
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complex covx(NH)
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real s1a(NH),s2a(NH)
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integer mettab(0:255,0:1) !Metric table
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integer data4a(9) !Decoded data (8-bit byte values)
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integer data4(12) !Decoded data (6-bit byte values)
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integer*1 data1(13)
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integer*1 isync(43)
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integer*1 chansym1(258),datsym2(215)
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logical first,window
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integer*1 i1
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equivalence (i1,i4)
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common/mscom/id(1440000),s1(215,703),s2(215,703)
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data first/.true./
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save
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if(first) then
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pi=4.0*atan(1.0)
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twopi=2.0*pi
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do i=1,nfft
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w(i)=(sin(i*pi/nfft))**2
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enddo
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df=48000.0/nfft
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ja=nint(2600.0)/df
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jb=nint(3400.0)/df
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iz=3000.0/df
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covx=0.
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kstep=4096
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read(10,3001) rsent
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3001 format(50f1.0)
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do i=1,258,6
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rsent(i)=0.
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enddo
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rsent=2.0*rsent - 1.0
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open(11,file='bpskmetrics.dat',status='old')
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bias=0.5
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scale=20.0
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do i=0,255
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read(11,*) xjunk,x0,x1
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mettab(i,0)=nint(scale*(x0-bias))
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mettab(i,1)=nint(scale*(x1-bias))
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enddo
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close(11)
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window=.false.
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first=.false.
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endif
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ib=k
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ia=k-kstep+1
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i0=k-nfft+1
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sq=0.
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do i=ia,ib
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sq=sq + (0.001*id(i))**2
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enddo
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write(13,1010) t,sq,db(sq)
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1010 format(3f12.3)
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if(k.lt.nfft) return
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x(1:nfft)=0.001*id(i0:ib)
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fac=2.0/nfft
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cx=fac*x
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if(window) cx=w*cx
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call four2a(cx,nfft,1,-1,1) !Forward c2c FFT
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do i=1,iz !Save spectrum for plot
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s1a(i)=real(cx(i+1))**2 + aimag(cx(i+1))**2
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enddo
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cx(1)=0.5*cx(1)
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cx(nh+2:nfft)=0.
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call four2a(cx,nfft,1,1,1) !Inverse c2c FFT
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if(window) then
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cx(1:nh)=cx(1:nh)+covx(1:nh) !Add previous segment's 2nd half
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covx(1:nh)=cx(nh+1:nfft) !Save 2nd half
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endif
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t=k/48000.0
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cx2=cx*cx
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call four2a(cx2,nfft,1,-1,1) !Forward c2c FFT of cx2
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spk0=0.
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do j=ja,jb
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sq=1.e-6*(real(cx2(j))**2 + aimag(cx2(j))**2)
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s2a(j)=sq
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f=(j-1)*df
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if(sq.gt.spk0) then
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spk0=sq
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f0=0.5*(f-3000.0)
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phi0=0.5*atan2(aimag(cx2(j)),real(cx2(j)))
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endif
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write(15,1020) f,sq
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1020 format(f10.3,f12.3)
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enddo
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slimit=2.5
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! if(spk0.gt.slimit) then
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if(abs(spk0-43.5).lt.0.1) then
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write(*,1030) t,f0,phi0,spk0
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1030 format('t:',f6.2,' f0:',f7.1,' phi0:',f6.2,' spk0:',f8.1)
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phi=phi0
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phi=3.9 !### test ###
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dphi=twopi*(f0+1500.0 -1.1)/48000.0
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p=0.
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nsum=0
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do i=1,nfft
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phi=phi+dphi
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if(phi.gt.twopi) phi=phi-twopi
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cx0(i)=cx(i)*cmplx(cos(phi),-sin(phi))
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pha=atan2(aimag(cx0(i)),real(cx0(i)))
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! write(18,1060) i,cx0(i),pha
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!1060 format(i6,5f12.3)
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j=mod(i-1,24) + 1
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! p(j)=p(j)+abs(cx0(i))
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p(j)=p(j) + real(cx0(i))**2 + aimag(cx0(i))**2
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nsum(j)=nsum(j)+1
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enddo
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do i=1,24
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p(i)=p(i)/nsum(i)
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write(20,1070) i,p(i)
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1070 format(i6,f12.3)
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enddo
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do i=19,nfft,24
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amp=abs(cx0(i))
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pha=atan2(aimag(cx0(i)),real(cx0(i)))
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j=(i+23)/24
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write(21,1060) j,cx0(i),pha,pha+twopi,amp
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1060 format(i6,5f12.3)
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softsym(j)=real(cx0(i))
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enddo
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! do iter=1,5
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rsent=cshift(rsent,86)
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lagmax=nfft/24 - 258
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do lag=0,lagmax
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sum=dot_product(rsent,softsym(lag+1:lag+258))
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if(abs(sum).gt.smax) then
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smax=abs(sum)
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lagpk=lag
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endif
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write(22,1080) lag,sum
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1080 format(i3,f12.3)
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enddo
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! rsent=cshift(rsent,43)
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! enddo
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do i=1,258
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j=mod(i-1+2580,258) + 1
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prod=rsent(j)*softsym(lagpk+i)
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nchsym=nint(0.5*(rsent(j)+1.0))
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write(23,1090) i,prod,rsent(j),softsym(lagpk+i),j,nchsym,lagpk+i
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1090 format(i5,3f10.3,3i5)
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enddo
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sym2=softsym(lagpk+1:lagpk+258)
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sym2=cshift(sym2,-86)
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do i=1,258
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i4=128 + nint(6.0*sym2(i))
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if(i4.lt.0) i4=0
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if(i4.gt.255) i4=255
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chansym1(i)=i1
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write(24,2001) i,sym2(i),i4,chansym1(i)
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2001 format(i6,f8.3,2i6)
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enddo
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endif
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end subroutine specjtms
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