From d857caa7f1a703731c69fdcdd1fdb6c7d0a99a7c Mon Sep 17 00:00:00 2001
From: Tom Rondeau <trondeau@vt.edu>
Date: Sun, 9 Sep 2012 14:34:08 -0400
Subject: digital: Fixes LMS and CMA equalizers.
filter: updated fir_filter_* by adding a method that allows the update of a single tap in the filter in a way that propagates to all of the aligned tap vectors. Mostly to support the adaptive equalizers.
---
gr-digital/lib/lms_dd_equalizer_cc_impl.cc | 59 ++++++++++++++++++++++++++----
1 file changed, 51 insertions(+), 8 deletions(-)
(limited to 'gr-digital/lib/lms_dd_equalizer_cc_impl.cc')
diff --git a/gr-digital/lib/lms_dd_equalizer_cc_impl.cc b/gr-digital/lib/lms_dd_equalizer_cc_impl.cc
index 6c217896c3..15008ca8e7 100644
--- a/gr-digital/lib/lms_dd_equalizer_cc_impl.cc
+++ b/gr-digital/lib/lms_dd_equalizer_cc_impl.cc
@@ -32,6 +32,8 @@
namespace gr {
namespace digital {
+ using namespace filter::kernel;
+
lms_dd_equalizer_cc::sptr
lms_dd_equalizer_cc::make(int num_taps, float mu, int sps,
constellation_sptr cnst)
@@ -47,25 +49,54 @@ namespace gr {
gr_make_io_signature(1, 1, sizeof(gr_complex)),
gr_make_io_signature(1, 1, sizeof(gr_complex)),
sps),
- filter::kernel::fir_filter_ccc(sps, std::vector<gr_complex>(num_taps, gr_complex(0,0))),
- d_cnst(cnst)
+ fir_filter_ccc(sps, std::vector<gr_complex>(num_taps, gr_complex(0,0))),
+ d_new_taps(num_taps, gr_complex(0,0)),
+ d_updated(false), d_cnst(cnst)
{
set_gain(mu);
if(num_taps > 0)
- d_taps[0] = 1.0;
- set_taps(d_taps);
+ d_new_taps[0] = 1.0;
+ fir_filter_ccc::set_taps(d_new_taps);
const int alignment_multiple =
volk_get_alignment() / sizeof(gr_complex);
set_alignment(std::max(1,alignment_multiple));
- set_history(num_taps+1);
+ set_history(num_taps);
}
lms_dd_equalizer_cc_impl::~lms_dd_equalizer_cc_impl()
{
}
+ void
+ lms_dd_equalizer_cc_impl::set_taps(const std::vector<gr_complex> &taps)
+ {
+ d_new_taps = taps;
+ d_updated = true;
+ }
+
+ std::vector<gr_complex>
+ lms_dd_equalizer_cc_impl::taps() const
+ {
+ return d_taps;
+ }
+
+ gr_complex
+ lms_dd_equalizer_cc_impl::error(const gr_complex &out)
+ {
+ gr_complex decision, error;
+ d_cnst->map_to_points(d_cnst->decision_maker(&out), &decision);
+ error = decision - out;
+ return error;
+ }
+
+ void
+ lms_dd_equalizer_cc_impl::update_tap(gr_complex &tap, const gr_complex &in)
+ {
+ tap += d_mu*conj(in)*d_error;
+ }
+
int
lms_dd_equalizer_cc_impl::work(int noutput_items,
gr_vector_const_void_star &input_items,
@@ -74,14 +105,26 @@ namespace gr {
const gr_complex *in = (const gr_complex *)input_items[0];
gr_complex *out = (gr_complex *)output_items[0];
+ if(d_updated) {
+ d_taps = d_new_taps;
+ set_history(d_taps.size());
+ d_updated = false;
+ return 0; // history requirements may have changed.
+ }
+
int j = 0;
- size_t l = d_taps.size();
+ size_t k, l = d_taps.size();
for(int i = 0; i < noutput_items; i++) {
out[i] = filter(&in[j]);
+ // Adjust taps
d_error = error(out[i]);
- for(size_t k=0; k < l; k++) {
- update_tap(d_taps[k], in[i+k]);
+ for(k = 0; k < l; k++) {
+ // Update tap locally from error.
+ update_tap(d_taps[k], in[j+k]);
+
+ // Update aligned taps in filter object.
+ fir_filter_ccc::update_tap(d_taps[k], k);
}
j += decimation();
--
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