diff options
| -rw-r--r-- | gnuradio-core/src/utils/Makefile.am | 1 | ||||
| -rw-r--r-- | gnuradio-core/src/utils/cic_comp_taps.m | 45 |
2 files changed, 46 insertions, 0 deletions
diff --git a/gnuradio-core/src/utils/Makefile.am b/gnuradio-core/src/utils/Makefile.am index a81e3ee98..78c80dab8 100644 --- a/gnuradio-core/src/utils/Makefile.am +++ b/gnuradio-core/src/utils/Makefile.am @@ -22,6 +22,7 @@ include $(top_srcdir)/Makefile.common EXTRA_DIST = \ + cic_comp_taps.m \ db_width.m \ filter_tools.m \ plot_freq_response.m \ diff --git a/gnuradio-core/src/utils/cic_comp_taps.m b/gnuradio-core/src/utils/cic_comp_taps.m new file mode 100644 index 000000000..e0e0c2ebd --- /dev/null +++ b/gnuradio-core/src/utils/cic_comp_taps.m @@ -0,0 +1,45 @@ +# +# Copyright 2008 Free Software Foundation, Inc. +# +# This file is part of GNU Radio +# +# GNU Radio is free software; you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation; either version 3, or (at your option) +# any later version. +# +# GNU Radio is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with GNU Radio; see the file COPYING. If not, write to +# the Free Software Foundation, Inc., 51 Franklin Street, +# Boston, MA 02110-1301, USA. +# + +# See Altera Application Note AN455 +# +# R = decimation factor, 8-256 +# Fc = passband (one-sided) cutoff frequency +# L = number of taps + +function taps = cic_comp_taps(R, Fc, L) + M = 1; %% Differential delay + N = 4; %% Number of stages + B = 18; %% Coeffi. Bit-width + Fs = 64e6; %% (High) Sampling freq in Hz before decimation + Fo = R*Fc/Fs; %% Normalized Cutoff freq; 0<Fo<=0.5/M; + p = 2e3; %% Granularity + s = 0.25/p; %% Step size + fp = [0:s:Fo]; %% Pass band frequency samples + fs = (Fo+s):s:0.5; %% Stop band frequency samples + f = [fp fs]*2; %% Normalized frequency samples; 0<=f<=1 + Mp = ones(1,length(fp)); %% Pass band response; Mp(1)=1 + Mp(2:end) = abs( M*R*sin(pi*fp(2:end)/R)./sin(pi*M*fp(2:end))).^N; + Mf = [Mp zeros(1,length(fs))]; + f(end) = 1; + h = fir2(L,f,Mf); %% Filter length L+1 + taps = h/sum(h); %% Floating point coefficients +endfunction |