README
1#
2# Copyright 2002 Free Software Foundation, Inc.
3#
4# This file is part of GNU Radio
5#
6# GNU Radio is free software; you can redistribute it and/or modify
7# it under the terms of the GNU General Public License as published by
8# the Free Software Foundation; either version 3, or (at your option)
9# any later version.
10#
11# GNU Radio is distributed in the hope that it will be useful,
12# but WITHOUT ANY WARRANTY; without even the implied warranty of
13# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14# GNU General Public License for more details.
15#
16# You should have received a copy of the GNU General Public License
17# along with GNU Radio; see the file COPYING. If not, write to
18# the Free Software Foundation, Inc., 51 Franklin Street,
19# Boston, MA 02110-1301, USA.
20#
21
22
23This file contains the source for gen_interpolator_taps, a program
24which generates optimal interpolator taps for a fractional
25interpolator.
26
27The ideal interpolator requires an infinite tap FIR filter to
28realize. We design a separate 8 tap filter for each value of mu,
29the fractional delay, that we are interested in. The taps are
30selected such that the mean squared error between the ideal frequency
31response and the approximation is mininimized over all frequencies of
32interest. In this implementation we define ``frequencies of
33interest'' as those from -B to +B, where B = 1/(4*Ts), where Ts is the
34sampling period.
35
36For a detailed look at what this is all about, please see Chapter 9 of
37"Digital Communication Receivers: Synchronization, Channel Estimation
38and Signal Processing" by Meyr, Moeneclaey and Fechtel, ISBN 0-471-50275-8
39
40NOTE, if you're running gen_interpolator_taps and it seg faults in
41RANDOM, you're probably using g77-2.96. The fix is to use g77 3.0 or later
42
43 cd <top_of_build_tree>
44 rm config.cache
45 export F77=g77-3.0.4
46 ./configure
47 make
48