WSJT-X/lib/symspec.f90

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subroutine symspec(k,ntrperiod,nsps,ndiskdat,nb,nbslider,pxdb,s,f0a,df3, &
ihsym,nzap,slimit,lstrong)
! Input:
! k pointer to the most recent new data
! ntrperiod T/R sequence length, minutes
! nsps samples per symbol (12000 Hz)
! ndiskdat 0/1 to indicate if data from disk
! nb 0/1 status of noise blanker (off/on)
! nbslider NB setting, 0-100
! Output:
! pxdb power (0-60 dB)
! s spectrum for waterfall display
! ihsym index number of this half-symbol (1-322)
! nzap number of samples zero'ed by noise blanker
! slimit NB scale adjustment
! lstrong true if strong signal at this freq
parameter (NMAX=1800*12000) !Total sample intervals per 30 minutes
parameter (NDMAX=1800*1500) !Sample intervals at 1500 Hz rate
parameter (NSMAX=22000) !Max length of saved spectra
parameter (NFFT1=1024)
parameter (NFFT2=1024,NFFT2A=NFFT2/8)
parameter (MAXFFT3=32768)
real*4 s(NSMAX),w(NFFT1),w3(MAXFFT3)
real*4 stmp(NFFT2/2)
real*4 x0(NFFT1),x1(NFFT1)
real*4 x2(NFFT1+105)
real*4 xx(NMAX)
complex cx(0:MAXFFT3-1)
logical*1 lstrong(0:1023) !Should be (0:512)
integer*2 id2
complex c0
common/jt9com/id2(NMAX),ss(184,NSMAX),savg(NSMAX),c0(NDMAX), &
nutc,npts8,junk(20)
data rms/999.0/,k0/99999999/,ntrperiod0/0/,nfft3z/0/
save
if(ntrperiod.eq.1) nfft3=1024
if(ntrperiod.eq.2) nfft3=2048
if(ntrperiod.eq.5) nfft3=6144
if(ntrperiod.eq.10) nfft3=12288
if(ntrperiod.eq.30) nfft3=32768
jstep=nsps/16
if(k.gt.NMAX) go to 999
if(k.lt.nfft3) then
ihsym=0
go to 999 !Wait for enough samples to start
endif
if(nfft3.ne.nfft3z) then
pi=4.0*atan(1.0)
do i=1,nfft3
w3(i)=2.0*(sin(i*pi/nfft3))**2 !Window for nfft3
enddo
stmp=0.
nfft3z=nfft3
endif
if(k.lt.k0) then
ja=-3*jstep
savg=0.
ihsym=0
k1=0
k8=0
x2=0.
if(ndiskdat.eq.0) id2(k+1:60*ntrperiod*12000)=0
endif
k0=k
nzap=0
sigmas=1.0*(10.0**(0.01*nbslider)) + 0.7
peaklimit=sigmas*max(10.0,rms)
faclim=3.0
px=0.
df2=12000.0/NFFT2
nwindow=2
! nwindow=0 !### No windowing ###
kstep1=NFFT1
if(nwindow.ne.0) kstep1=NFFT1/2
fac=2.0/NFFT1
nblks=(k-k1)/kstep1
do nblk=1,nblks
j=k1+1
do i=1,NFFT1
x0(i)=id2(k1+i)
enddo
call timf2(x0,k,NFFT1,nwindow,nb,peaklimit,faclim,x1, &
slimit,lstrong,px,nzap)
! Mix at 1500 Hz, lowpass at +/-750 Hz, and downsample to 1500 Hz complex.
x2(106:105+kstep1)=x1(1:kstep1)
call fil3(x2,kstep1+105,c0(k8+1),n2)
x2(1:105)=x1(kstep1-104:kstep1) !Save 105 trailing samples
k1=k1+kstep1
k8=k8+kstep1/8
enddo
npts8=k8
ja=ja+jstep !Index of first sample
nsum=nblks*kstep1 - nzap
!###
! if(nzap/178.lt.50 .and. (ndiskdat.eq.0 .or. ihsym.lt.280)) then
if(nsum.le.0) nsum=1
rms=sqrt(px/nsum)
! endif
pxdb=0.
if(rms.gt.0.0) pxdb=20.0*log10(rms)
if(pxdb.gt.60.0) pxdb=60.0
!###
! if(ja.lt.0 .or. npts8.lt.ja+nfft3) go to 999
if(ja.gt.0) then
do i=0,nfft3-1 !Copy data into cx
cx(i)=c0(ja+i+1)
enddo
ihsym=ihsym+1
cx(0:nfft3-1)=w3(1:nfft3)*cx(0:nfft3-1) !Apply window w3
call four2a(cx,nfft3,1,1,1) !Third forward FFT (X)
n=min(184,ihsym)
df3=1500.0/nfft3
i0=nint(-500.0/df3)
iz=min(NSMAX,nint(1000.0/df3))
fac=(1.0/nfft3)**2
do i=1,iz
j=i0+i-1
if(j.lt.0) j=j+nfft3
sx=fac*(real(cx(j))**2 + aimag(cx(j))**2)
ss(n,i)=sx
savg(i)=savg(i) + sx
s(i)=sx
enddo
endif
999 continue
! write(71,3003) k,nsps,ihsym,nfft3,pxdb,df3,s(250)
!3003 format(4i9,3f11.3)
! flush(71)
return
end subroutine symspec