WSJT-X/lib/spec66.f90
2020-08-01 09:24:59 -04:00

45 lines
1.3 KiB
Fortran

subroutine spec66(c0,s3)
parameter (LL=3*64) !Frequency channels
parameter (NN=63) !Data symbols
parameter (NSPS=960) !Samples per symbol at 6000 Hz
parameter (NMAX=85*NSPS)
complex c0(0:NMAX-1) !Synchrinized complex data
complex cs(0:NSPS-1) !Complex symbol spectrum
real s3(LL,NN) !Synchronized symbol spectra
real xbase0(LL),xbase(LL)
fac=1.0/NSPS
ja=-NSPS
do j=1,NN
ja=ja+NSPS
if(mod(ja/NSPS,4).eq.0) ja=ja+NSPS
jb=ja+NSPS-1
cs=fac*c0(ja:jb)
call four2a(cs,NSPS,1,-1,1) !c2c FFT to frequency
do ii=1,LL
i=ii-65
if(i.lt.0) i=i+NSPS
s3(ii,j)=real(cs(i))**2 + aimag(cs(i))**2
enddo
enddo
df=6000.0/NSPS
do i=1,LL
call pctile(s3(i,1:NN),NN,45,xbase0(i)) !Get baseline for passband shape
enddo
nh=9
xbase(1:nh-1)=sum(xbase0(1:nh-1))/(nh-1.0)
xbase(LL-nh+1:LL)=sum(xbase0(LL-nh+1:LL))/(nh-1.0)
do i=nh,LL-nh
xbase(i)=sum(xbase0(i-nh+1:i+nh))/(2*nh+1) !Smoothed passband shape
enddo
do i=1,LL
s3(i,1:NN)=s3(i,1:NN)/(xbase(i)+0.001) !Apply frequency equalization
enddo
return
end subroutine spec66