README change

1 files changed, 40 insertions, 0 deletions

diff --git a/gnuradio-core/src/utils/plotfft.m b/gnuradio-core/src/utils/plotfft.m
new file mode 100644
index 000000000..20a2efd4c
--- /dev/null
+++ b/gnuradio-core/src/utils/plotfft.m
@@ -0,0 +1,40 @@
+#
+# 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 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.
+#
+
+function plotfft (data, sample_rate)
+
+  if (nargin == 1)
+    sample_rate = 1.0;
+  endif;
+
+  if ((m = nargchk (1,2,nargin)))
+    usage (m);
+  endif;
+
+  len = length(data);
+  s = fft (data.*kaiser(len, 5));
+
+  incr = sample_rate/len;
+  min_x = -sample_rate/2;
+  max_x = sample_rate/2 - incr;
+  plot (min_x:incr:max_x, abs(fftshift(s)));
+
+endfunction