program t1

  parameter (NFFT=1024,NH=NFFT/2)
  real w(-24:24)
  real x(0:NFFT-1)
  complex cx(0:NH)
  equivalence (x,cx)

! FIR lowpass filter designed using ScopeFIR

! fsample     = 48000 Hz
! Ntaps       = 49
! fc          = 4500  Hz
! fstop       = 6000  Hz
! Ripple      = 1     dB
! Stop Atten  = 40    dB
! fout        = 12000 Hz
! Filter coefficients:
  data w/                                                                 &
        0.000861074040, 0.010051920210, 0.010161983649, 0.011363155076,   &
        0.008706594219, 0.002613872664,-0.005202883094,-0.011720748164,   &
       -0.013752163325,-0.009431602741, 0.000539063909, 0.012636767098,   &
        0.021494659597, 0.021951235065, 0.011564169382,-0.007656470131,   &
       -0.028965787341,-0.042637874109,-0.039203309748,-0.013153301537,   &
        0.034320769178, 0.094717832646, 0.154224604789, 0.197758325022,   &
        0.213715139513, 0.197758325022, 0.154224604789, 0.094717832646,   &
        0.034320769178,-0.013153301537,-0.039203309748,-0.042637874109,   &
       -0.028965787341,-0.007656470131, 0.011564169382, 0.021951235065,   &
        0.021494659597, 0.012636767098, 0.000539063909,-0.009431602741,   &
       -0.013752163325,-0.011720748164,-0.005202883094, 0.002613872664,   &
        0.008706594219, 0.011363155076, 0.010161983649, 0.010051920210,   &
        0.000861074040/

  x=0.
  do i=-24,24
     j=i
     if(j.lt.0) j=j+NFFT
     x(j)=w(i)
  enddo

  call four2a(x,NFFT,1,-1,0)                     !r2c FFT

  df=48000.0/NFFT
  do i=0,NH
     y=abs(cx(i))
     s=y*y
     f=i*df
     write(13,1000) f,y,s,db(s),cx(i)
1000 format(6f12.6)
  enddo

end program t1