diff options
| author | jcorgan <jcorgan@221aa14e-8319-0410-a670-987f0aec2ac5> | 2006-08-03 04:51:51 +0000 |
|---|---|---|
| committer | jcorgan <jcorgan@221aa14e-8319-0410-a670-987f0aec2ac5> | 2006-08-03 04:51:51 +0000 |
| commit | 5d69a524f81f234b3fbc41d49ba18d6f6886baba (patch) | |
| tree | b71312bf7f1e8d10fef0f3ac6f28784065e73e72 /gnuradio-core/src/utils/db_width.m | |
Houston, we have a trunk.
git-svn-id: http://gnuradio.org/svn/gnuradio/trunk@3122 221aa14e-8319-0410-a670-987f0aec2ac5
Diffstat (limited to 'gnuradio-core/src/utils/db_width.m')
| -rw-r--r-- | gnuradio-core/src/utils/db_width.m | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/gnuradio-core/src/utils/db_width.m b/gnuradio-core/src/utils/db_width.m new file mode 100644 index 0000000000..c12dfd1ccc --- /dev/null +++ b/gnuradio-core/src/utils/db_width.m @@ -0,0 +1,35 @@ +% +% Copyright 2001 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 2, 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., 59 Temple Place - Suite 330, +% Boston, MA 02111-1307, USA. + +%% find the N-dB width of the given filter +%% E.g., to find the 3-dB width, use width = db_width (taps, -3.0) +%% the result is normalized to nyquist == 1 + +function width = db_width (taps, db) + [H,w] = freqz (taps, 1, 4096); + Habs = abs(H); + max_H = max(Habs); + min_H = min(Habs); + threshold = max_H * 10^(db/20); + if (min_H > threshold) + error ("The %g dB point is never reached", db); + end + above = Habs >= threshold; + width = sum(above) / length (above); |