2017-04-19 15:55:11 -04:00
|
|
|
subroutine getfc1(c,fc1)
|
|
|
|
|
|
|
|
|
|
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 c(0:NZ-1) !Complex waveform
|
|
|
|
|
complex c2(0:NFFT1-1) !Short spectra
|
|
|
|
|
real s(-NH1+1:NH1) !Coarse spectrum
|
|
|
|
|
|
|
|
|
|
nspec=NZ/NFFT1
|
|
|
|
|
fs=12000.0/72.0
|
|
|
|
|
df1=fs/NFFT1
|
|
|
|
|
s=0.
|
|
|
|
|
do k=1,nspec
|
|
|
|
|
ia=(k-1)*N2
|
|
|
|
|
ib=ia+N2-1
|
|
|
|
|
c2(0:N2-1)=c(ia:ib)
|
|
|
|
|
c2(N2:)=0.
|
|
|
|
|
call four2a(c2,NFFT1,1,-1,1)
|
|
|
|
|
do i=0,NFFT1-1
|
|
|
|
|
j=i
|
|
|
|
|
if(j.gt.NH1) j=j-NFFT1
|
|
|
|
|
s(j)=s(j) + real(c2(i))**2 + aimag(c2(i))**2
|
|
|
|
|
enddo
|
|
|
|
|
enddo
|
|
|
|
|
! call smo121(s,NFFT1)
|
|
|
|
|
smax=0.
|
|
|
|
|
ipk=0
|
|
|
|
|
fc1=0.
|
|
|
|
|
ia=nint(40.0/df1)
|
|
|
|
|
do i=-ia,ia
|
|
|
|
|
f=i*df1
|
|
|
|
|
if(s(i).gt.smax) then
|
|
|
|
|
smax=s(i)
|
|
|
|
|
ipk=i
|
|
|
|
|
fc1=f
|
|
|
|
|
endif
|
2017-04-20 15:21:54 -04:00
|
|
|
! write(51,3001) f,s(i),db(s(i))
|
2017-04-19 15:55:11 -04:00
|
|
|
! 3001 format(f10.3,e12.3,f10.3)
|
|
|
|
|
enddo
|
|
|
|
|
|
|
|
|
|
! The following is for testing SNR calibration:
|
|
|
|
|
! sp3n=(s(ipk-1)+s(ipk)+s(ipk+1)) !Sig + 3*noise
|
|
|
|
|
! base=(sum(s)-sp3n)/(NFFT1-3.0) !Noise per bin
|
|
|
|
|
! psig=sp3n-3*base !Sig only
|
|
|
|
|
! pnoise=(2500.0/df1)*base !Noise in 2500 Hz
|
|
|
|
|
! xsnrdb=db(psig/pnoise)
|
|
|
|
|
|
|
|
|
|
return
|
|
|
|
|
end subroutine getfc1
|
