WSJT-X/lib/fsk4hf/msksoftsym.f90

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subroutine msksoftsym(zz,aa,bb,id,nterms,ierror,rxdata,nhard0,nhard, &
nhardsync0,nhardsync)
parameter (KK=84) !Information bits (72 + CRC12)
parameter (ND=168) !Data symbols: LDPC (168,84), r=1/2
parameter (NS=65) !Sync symbols (2 x 26 + Barker 13)
parameter (NR=3) !Ramp up/down
parameter (NN=NR+NS+ND) !Total symbols (236)
parameter (NSPS=16) !Samples per MSK symbol (16)
parameter (N2=2*NSPS) !Samples per OQPSK symbol (32)
parameter (N13=13*N2) !Samples in central sync vector (416)
parameter (NZ=NSPS*NN) !Samples in baseband waveform (3760)
parameter (NFFT1=4*NSPS,NH1=NFFT1/2)
complex zz(NS+ND) !Complex symbol values (intermediate)
complex z,z0
real rxdata(ND) !Soft symbols
real aa(20),bb(20) !Fitted polyco's
integer id(NS+ND) !NRZ values (+/-1) for Sync and Data
integer ierror(NS+ND)
n=0
ierror=0
do j=1,117
xx=j*2.0/117.0 - 1.0
yii=1.
yqq=0.
if(nterms.gt.0) then
yii=aa(1)
yqq=bb(1)
do i=2,nterms
yii=yii + aa(i)*xx**(i-1)
yqq=yqq + bb(i)*xx**(i-1)
enddo
endif
z0=cmplx(yii,yqq)
z=zz(j)*conjg(z0)
p=real(z)
if(abs(id(j)).eq.2) then
if(real(z)*id(j).lt.0) then !Sync bit
nhardsync=nhardsync+1
nhardsync0=nhardsync0+1
ierror(j)=2
endif
else
n=n+1 !Data bit
rxdata(n)=p
ierr=0
if(id(j)*p.lt.0) then
ierr=1
ierror(j)=1
endif
nhard0=nhard0+ierr
nhard=nhard+ierr
endif
enddo
do j=118,233
xx=(j-116.5)*2.0/117.0 - 1.0
yii=1.
yqq=0.
if(nterms.gt.0) then
yii=aa(1)
yqq=bb(1)
do i=2,nterms
yii=yii + aa(i)*xx**(i-1)
yqq=yqq + bb(i)*xx**(i-1)
enddo
endif
z0=cmplx(yii,yqq)
z=zz(j)*conjg(z0)
p=aimag(z)
n=n+1
rxdata(n)=p
ierr=0
if(id(j)*p.lt.0) then
ierr=1
ierror(j)=1
endif
nhard0=nhard0+ierr
nhard=nhard+ierr
enddo
return
end subroutine msksoftsym