77 lines
2.4 KiB
Plaintext
77 lines
2.4 KiB
Plaintext
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subroutine cpolyfit(c,pp,id,maxn,aa,bb,zz,nhardsync)
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parameter (KK=84) !Information bits (72 + CRC12)
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parameter (ND=168) !Data symbols: LDPC (168,84), r=1/2
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parameter (NS=65) !Sync symbols (2 x 26 + Barker 13)
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parameter (NR=3) !Ramp up/down
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parameter (NN=NR+NS+ND) !Total symbols (236)
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parameter (NSPS=16) !Samples per MSK symbol (16)
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parameter (N2=2*NSPS) !Samples per OQPSK symbol (32)
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parameter (N13=13*N2) !Samples in central sync vector (416)
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parameter (NZ=NSPS*NN) !Samples in baseband waveform (3760)
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parameter (NFFT1=4*NSPS,NH1=NFFT1/2)
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complex c(0:NZ-1) !Complex waveform
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complex zz(NS+ND) !Complex symbol values (intermediate)
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complex z,z0
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real x(NS),yi(NS),yq(NS) !For complex polyfit
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real pp(2*NSPS) !Shaped pulse for OQPSK
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real aa(20),bb(20) !Fitted polyco's
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integer id(NS+ND) !NRZ values (+/-1) for Sync and Data
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ib=NSPS-1
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ib2=N2-1
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n=0
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do j=1,117 !First-pass demodulation
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ia=ib+1
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ib=ia+N2-1
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zz(j)=sum(pp*c(ia:ib))/NSPS
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if(abs(id(j)).eq.2) then !Save all sync symbols
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n=n+1
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x(n)=float(ia+ib)/NZ - 1.0
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yi(n)=real(zz(j))*0.5*id(j)
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yq(n)=aimag(zz(j))*0.5*id(j)
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! write(54,1225) n,x(n),yi(n),yq(n)
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!1225 format(i5,3f12.4)
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endif
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if(j.le.116) then
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zz(j+117)=sum(pp*c(ia+NSPS:ib+NSPS))/NSPS
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endif
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enddo
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aa=0.
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bb=0.
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nterms=0
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chisqa=0.
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chisqb=0.
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if(maxn.gt.0) then
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npts=n
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mode=0
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nterms=maxn
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call polyfit4(x,yi,yi,npts,nterms,mode,aa,chisqa)
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call polyfit4(x,yq,yq,npts,nterms,mode,bb,chisqb)
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endif
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nhardsync=0
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do j=1,117
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if(abs(id(j)).ne.2) cycle
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xx=j*2.0/117.0 - 1.0
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yii=1.
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yqq=0.
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if(nterms.gt.0) then
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yii=aa(1)
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yqq=bb(1)
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do i=2,nterms
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yii=yii + aa(i)*xx**(i-1)
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yqq=yqq + bb(i)*xx**(i-1)
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enddo
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endif
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z0=cmplx(yii,yqq)
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z=zz(j)*conjg(z0)
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p=real(z)
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if(p*id(j).lt.0) nhardsync=nhardsync+1
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enddo
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return
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end subroutine cpolyfit
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