73 lines
3.1 KiB
Plaintext
73 lines
3.1 KiB
Plaintext
|
subroutine fil3c(c1,n1,c2,n2)
|
||
|
|
|
||
|
|
! FIR complex-to-complex low-pass filter designed with ScopeFIR
|
||
|
|
!
|
||
|
|
!-----------------------------------------------
|
||
|
|
! fsample (Hz) 12000 Input sample rate
|
||
|
|
! Ntaps 113 Number of filter taps
|
||
|
|
! fc (Hz) 500 Cutoff frequency
|
||
|
|
! fstop (Hz) 750 Lower limit of stopband
|
||
|
|
! Ripple (dB) 0.2 Ripple in passband
|
||
|
|
! Stop Atten (dB) 50 Stopband attenuation
|
||
|
|
! fout (Hz) 1500 Output sample rate
|
||
|
|
|
||
|
|
! Suggest calling with n1 = 8*n2 + 105, where n2 is the desired number
|
||
|
|
! of 1500 Hz output samples.
|
||
|
|
|
||
|
|
parameter (NTAPS=113)
|
||
|
|
parameter (NH=NTAPS/2)
|
||
|
|
parameter (NDOWN=8) !Downsample ratio = 1/8
|
||
|
|
complex c1(n1)
|
||
|
|
complex c2(n1/NDOWN)
|
||
|
|
complex z
|
||
|
|
|
||
|
|
! Filter coefficients:
|
||
|
|
real a(-NH:NH)
|
||
|
|
data a/ &
|
||
|
|
-0.001818142144,-0.000939132050,-0.001044063556,-0.001042685542, &
|
||
|
|
-0.000908957610,-0.000628132309,-0.000202701465, 0.000346307629, &
|
||
|
|
0.000978154552, 0.001634336295, 0.002243121592, 0.002726064379, &
|
||
|
|
0.003006201675, 0.003018055983, 0.002717699575, 0.002091546534, &
|
||
|
|
0.001162489032,-0.000007904811,-0.001321554806,-0.002649908053, &
|
||
|
|
-0.003843608784,-0.004747338068,-0.005218967042,-0.005148229529, &
|
||
|
|
-0.004470167307,-0.003177923811,-0.001335998901, 0.000915924193, &
|
||
|
|
0.003386100636, 0.005818719744, 0.007939147967, 0.009465071347, &
|
||
|
|
0.010145641899, 0.009787447819, 0.008285915754, 0.005645995244, &
|
||
|
|
0.001995842303,-0.002410369720,-0.007202515555,-0.011916811719, &
|
||
|
|
-0.016028350845,-0.018993391440,-0.020297455955,-0.019503792208, &
|
||
|
|
-0.016298136197,-0.010526834635,-0.002223837363, 0.008378305829, &
|
||
|
|
0.020854478160, 0.034608532659, 0.048909701463, 0.062944127288, &
|
||
|
|
0.075874892030, 0.086903764340, 0.095332017649, 0.100619428175, &
|
||
|
|
0.102420526192, 0.100619428175, 0.095332017649, 0.086903764340, &
|
||
|
|
0.075874892030, 0.062944127288, 0.048909701463, 0.034608532659, &
|
||
|
|
0.020854478160, 0.008378305829,-0.002223837363,-0.010526834635, &
|
||
|
|
-0.016298136197,-0.019503792208,-0.020297455955,-0.018993391440, &
|
||
|
|
-0.016028350845,-0.011916811719,-0.007202515555,-0.002410369720, &
|
||
|
|
0.001995842303, 0.005645995244, 0.008285915754, 0.009787447819, &
|
||
|
|
0.010145641899, 0.009465071347, 0.007939147967, 0.005818719744, &
|
||
|
|
0.003386100636, 0.000915924193,-0.001335998901,-0.003177923811, &
|
||
|
|
-0.004470167307,-0.005148229529,-0.005218967042,-0.004747338068, &
|
||
|
|
-0.003843608784,-0.002649908053,-0.001321554806,-0.000007904811, &
|
||
|
|
0.001162489032, 0.002091546534, 0.002717699575, 0.003018055983, &
|
||
|
|
0.003006201675, 0.002726064379, 0.002243121592, 0.001634336295, &
|
||
|
|
0.000978154552, 0.000346307629,-0.000202701465,-0.000628132309, &
|
||
|
|
-0.000908957610,-0.001042685542,-0.001044063556,-0.000939132050, &
|
||
|
|
-0.001818142144/
|
||
|
|
save a
|
||
|
|
|
||
|
|
n2=(n1-NTAPS+NDOWN)/NDOWN
|
||
|
|
k0=NH-NDOWN+1
|
||
|
|
|
||
|
|
! Loop over all output samples
|
||
|
|
do i=1,n2
|
||
|
|
z=0.
|
||
|
|
k=k0 + NDOWN*i
|
||
|
|
do j=-NH,NH
|
||
|
|
z=z + c1(j+k)*a(j)
|
||
|
|
enddo
|
||
|
|
c2(i)=z
|
||
|
|
enddo
|
||
|
|
|
||
|
|
return
|
||
|
|
end subroutine fil3c
|