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Better way to apply xdt to received signal.

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This commit is contained in:
Joe Taylor 2024-01-31 12:08:50 -05:00
parent efedc50fe1
commit a7ea051cb0
1 changed files with 8 additions and 29 deletions
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37
lib/superfox/synctest.f90
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@ -15,7 +15,6 @@ program synctest
complex cnoise(NMAX) !Complex noise
complex crcvd(NMAX) !Signal as received
complex c(0:NFFT-1)
complex w,wstep,w0,wstep0
integer ipk(2)
character fname*17,arg*12
character*1 line(-30:30),mark(0:5)
@ -42,8 +41,6 @@ program synctest
rms=100.
fsample=12000.0 !Sample rate (Hz)
twopi=8.0*atan(1.0)
tsync=NS*nsps/fsample
baud=12000.0/nsps !Keying rate, 11.719 baud for nsps=1024
h=default_header(12000,NMAX)
fname='000000_000001.wav'
@ -63,30 +60,11 @@ program synctest
bandwidth_ratio=2500.0/6000.0
sig=sqrt(2*bandwidth_ratio)*10.0**(0.05*snrdb)
if(snrdb.gt.90.0) sig=1.0
w0=1.0
w=1.0
a0=1500.0+ syncwidth/2.0 !Frequency at midpoint of LO waveform
a1=f0 + syncwidth/2.0 !Frequency at midpoint of sync waveform
a2=2.0*syncwidth/tsync !Frequency drift rate
! Generate complex LO and sync signal
x0=0.5*(nsync+1)
s=2.0/nsync
cdat=0.
i0=nint(60.0*nsps + xdt*12000.0)
do i=1,nsync
if(i.eq.nsync/2+1) a2=-a2 !Reverse sign of drift at midpoint
x=s*(i-x0)
dphi0=(a0 + x*a2) * (twopi/fsample)
wstep0=cmplx(cos(dphi0),sin(dphi0))
w0=w0*wstep0
dphi=(a1 + x*a2) * (twopi/fsample)
wstep=cmplx(cos(dphi),sin(dphi))
w=w*wstep
clo(i)=conjg(sig*w0)
cdat(i+i0)=sig*w
enddo
call gen_sfox(f0,fsample,syncwidth,cdat,clo)
cdat=sig*cdat
crcvd=0.
crcvd(1:NMAX)=cshift(cdat(1:NMAX),-nint(xdt*fsample)) + cnoise
dat=aimag(cdat(1:NMAX)) + xnoise !Add generated AWGN noise
fac=32767.0
@ -95,15 +73,13 @@ program synctest
write(10) h,iwave(1:NMAX) !Save the .wav file
close(10)
crcvd=0.
crcvd(1:NMAX)=cdat(1:NMAX) + cnoise
if(fspread.ne.0 .or. delay.ne.0) call watterson(crcvd,NMAX,NZ,fsample, &
delay,fspread)
ccf=0.
df=12000.0/NFFT !0.366211
i1=60*nsps
i1=ND1*nsps
do m=-MMAX,MMAX
lag=100*m
c(0:nsync-1)=crcvd(i1+1+lag:i1+nsync+lag)*clo(1:nsync)
@ -146,3 +122,6 @@ program synctest
1110 format('err:',f6.1,f12.2)
999 end program synctest
include 'gen_sfox.f90'