WSJT-X/lib/fil3.f90
Joe Taylor d397ed7bdf Add fil3.f90.
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@2654 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
2012-10-10 19:25:28 +00:00

160 lines
6.5 KiB
Fortran

subroutine fil3(x1,n1,c2,n2)
! FIR real-to-complex filter designed using 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
! fmix (HZ) 1500 Mixing frequency
! fout (Hz) 1500 Output sample rate
! Resulting passband is 1000 - 2000 Hz
! 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
real x1(n1)
complex z
complex c2(n1/NDOWN)
! Filter coefficients:
complex ca(-NH:NH)
data ca/ &
(-0.001818142144, 0.000000000000), &
(-0.000664066641,-0.000664066640), &
(-0.000000000000,-0.001044063550), &
( 0.000737290018,-0.000737290010), &
( 0.000908957610,-0.000000000000), &
( 0.000444156615, 0.000444156610), &
(-0.000000000000, 0.000202701460), &
( 0.000244876473,-0.000244876470), &
( 0.000978154552, 0.000000000000), &
( 0.001155650277, 0.001155650270), &
( 0.000000000000, 0.002243121590), &
(-0.001927618608, 0.001927618600), &
(-0.003006201675, 0.000000000000), &
(-0.002134087852,-0.002134087850), &
( 0.000000000000,-0.002717699570), &
( 0.001478946738,-0.001478946730), &
( 0.001162489032, 0.000000000000), &
(-0.000005589545,-0.000005589540), &
(-0.000000000000,-0.001321554800), &
( 0.001873767954,-0.001873767950), &
( 0.003843608784,-0.000000000000), &
( 0.003356874940, 0.003356874940), &
(-0.000000000000, 0.005218967040), &
(-0.003640348011, 0.003640348010), &
(-0.004470167307, 0.000000000000), &
(-0.002247131477,-0.002247131470), &
(-0.000000000000,-0.001335998900), &
(-0.000647656208, 0.000647656200), &
(-0.003386100636, 0.000000000000), &
(-0.004114456189,-0.004114456180), &
( 0.000000000000,-0.007939147960), &
( 0.006692816134,-0.006692816130), &
( 0.010145641899, 0.000000000000), &
( 0.006920770724, 0.006920770720), &
( 0.000000000000, 0.008285915750), &
(-0.003992321524, 0.003992321520), &
(-0.001995842303, 0.000000000000), &
( 0.001704388774, 0.001704388770), &
(-0.000000000000, 0.007202515550), &
(-0.008426458377, 0.008426458370), &
(-0.016028350845, 0.000000000000), &
(-0.013430355885,-0.013430355880), &
(-0.000000000000,-0.020297455950), &
( 0.013791263729,-0.013791263720), &
( 0.016298136197,-0.000000000000), &
( 0.007443596155, 0.007443596150), &
(-0.000000000000, 0.002223837360), &
( 0.005924356866,-0.005924356860), &
( 0.020854478160, 0.000000000000), &
( 0.024471928130, 0.024471928130), &
( 0.000000000000, 0.048909701460), &
(-0.044508219241, 0.044508219240), &
(-0.075874892030, 0.000000000000), &
(-0.061450241075,-0.061450241070), &
( 0.000000000000,-0.095332017640), &
( 0.071148679982,-0.071148679980), &
( 0.102420526192, 0.000000000000), &
( 0.071148679982, 0.071148679980), &
( 0.000000000000, 0.095332017640), &
(-0.061450241075, 0.061450241070), &
(-0.075874892030, 0.000000000000), &
(-0.044508219241,-0.044508219240), &
( 0.000000000000,-0.048909701460), &
( 0.024471928130,-0.024471928130), &
( 0.020854478160, 0.000000000000), &
( 0.005924356866, 0.005924356860), &
(-0.000000000000,-0.002223837360), &
( 0.007443596155,-0.007443596150), &
( 0.016298136197,-0.000000000000), &
( 0.013791263729, 0.013791263720), &
(-0.000000000000, 0.020297455950), &
(-0.013430355885, 0.013430355880), &
(-0.016028350845, 0.000000000000), &
(-0.008426458377,-0.008426458370), &
(-0.000000000000,-0.007202515550), &
( 0.001704388774,-0.001704388770), &
(-0.001995842303, 0.000000000000), &
(-0.003992321524,-0.003992321520), &
( 0.000000000000,-0.008285915750), &
( 0.006920770724,-0.006920770720), &
( 0.010145641899, 0.000000000000), &
( 0.006692816134, 0.006692816130), &
( 0.000000000000, 0.007939147960), &
(-0.004114456189, 0.004114456180), &
(-0.003386100636, 0.000000000000), &
(-0.000647656208,-0.000647656200), &
(-0.000000000000, 0.001335998900), &
(-0.002247131477, 0.002247131470), &
(-0.004470167307, 0.000000000000), &
(-0.003640348011,-0.003640348010), &
(-0.000000000000,-0.005218967040), &
( 0.003356874940,-0.003356874940), &
( 0.003843608784,-0.000000000000), &
( 0.001873767954, 0.001873767950), &
(-0.000000000000, 0.001321554800), &
(-0.000005589545, 0.000005589540), &
( 0.001162489032, 0.000000000000), &
( 0.001478946738, 0.001478946730), &
( 0.000000000000, 0.002717699570), &
(-0.002134087852, 0.002134087850), &
(-0.003006201675, 0.000000000000), &
(-0.001927618608,-0.001927618600), &
( 0.000000000000,-0.002243121590), &
( 0.001155650277,-0.001155650270), &
( 0.000978154552, 0.000000000000), &
( 0.000244876473, 0.000244876470), &
(-0.000000000000,-0.000202701460), &
( 0.000444156615,-0.000444156610), &
( 0.000908957610,-0.000000000000), &
( 0.000737290018, 0.000737290010), &
(-0.000000000000, 0.001044063550), &
(-0.000664066641, 0.000664066640), &
(-0.001818142144, 0.000000000000)/
save ca
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 + x1(j+k)*ca(j)
enddo
c2(i)=z
enddo
return
end subroutine fil3