From 54e947e394dcd2bbff2b49968adf7b0861f0851b Mon Sep 17 00:00:00 2001
From: Tom Rondeau <trondeau@vt.edu>
Date: Wed, 31 Oct 2012 11:42:07 -0400
Subject: analog: adding simple_squelch block to gr-analog with QA and GRC.
---
gr-analog/lib/simple_squelch_cc_impl.cc | 106 ++++++++++++++++++++++++++++++++
1 file changed, 106 insertions(+)
create mode 100644 gr-analog/lib/simple_squelch_cc_impl.cc
(limited to 'gr-analog/lib/simple_squelch_cc_impl.cc')
diff --git a/gr-analog/lib/simple_squelch_cc_impl.cc b/gr-analog/lib/simple_squelch_cc_impl.cc
new file mode 100644
index 0000000000..02ccc535da
--- /dev/null
+++ b/gr-analog/lib/simple_squelch_cc_impl.cc
@@ -0,0 +1,106 @@
+/* -*- c++ -*- */
+/*
+ * Copyright 2005,2010,2012 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.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "simple_squelch_cc_impl.h"
+#include <gr_io_signature.h>
+#include <cmath>
+
+namespace gr {
+ namespace analog {
+
+ simple_squelch_cc::sptr
+ simple_squelch_cc::make(double threshold_db, double alpha)
+ {
+ return gnuradio::get_initial_sptr
+ (new simple_squelch_cc_impl(threshold_db, alpha));
+ }
+
+ simple_squelch_cc_impl::simple_squelch_cc_impl(double threshold_db, double alpha)
+ : gr_sync_block("simple_squelch_cc",
+ gr_make_io_signature(1, 1, sizeof(gr_complex)),
+ gr_make_io_signature(1, 1, sizeof(gr_complex))),
+ d_unmuted(false), d_iir(alpha)
+ {
+ set_threshold(threshold_db);
+ }
+
+ simple_squelch_cc_impl::~simple_squelch_cc_impl()
+ {
+ }
+
+ void
+ simple_squelch_cc_impl::set_threshold(double decibels)
+ {
+ // convert to absolute threshold (mag squared)
+ d_threshold = std::pow(10.0, decibels/10);
+ }
+
+ double
+ simple_squelch_cc_impl::threshold() const
+ {
+ return 10 * log10(d_threshold);
+ }
+
+ void
+ simple_squelch_cc_impl::set_alpha(double alpha)
+ {
+ d_iir.set_taps(alpha);
+ }
+
+ std::vector<float>
+ simple_squelch_cc_impl::squelch_range() const
+ {
+ std::vector<float> r(3);
+ r[0] = -50.0; // min FIXME
+ r[1] = +50.0; // max FIXME
+ r[2] = (r[1] - r[0]) / 100; // step size
+
+ return r;
+ }
+
+ int
+ simple_squelch_cc_impl::work(int noutput_items,
+ gr_vector_const_void_star &input_items,
+ gr_vector_void_star &output_items)
+ {
+ const gr_complex *in = (const gr_complex*)input_items[0];
+ gr_complex *out = (gr_complex*)output_items[0];
+
+ for(int i = 0; i < noutput_items; i++) {
+ double mag_sqrd = in[i].real()*in[i].real() + in[i].imag()*in[i].imag();
+ double f = d_iir.filter(mag_sqrd);
+ if(f >= d_threshold)
+ out[i] = in[i];
+ else
+ out[i] = 0;
+ }
+
+ d_unmuted = d_iir.prev_output() >= d_threshold;
+ return noutput_items;
+ }
+
+ } /* namespace analog */
+} /* namespace gr */
--
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