From 612be3956603941f6cf530c090eba02d26d33bcd Mon Sep 17 00:00:00 2001
From: Tom Rondeau <trondeau@vt.edu>
Date: Wed, 10 Aug 2011 22:35:17 -0400
Subject: digital: updated constellation receiver to use loop bandwidth and
damping factor instead of setting alpha and beta independently. Also cleaning
up Costas loop a bit more.
---
.../lib/digital_constellation_receiver_cb.cc | 135 ++++++++++++++++++++-
1 file changed, 129 insertions(+), 6 deletions(-)
(limited to 'gr-digital/lib/digital_constellation_receiver_cb.cc')
diff --git a/gr-digital/lib/digital_constellation_receiver_cb.cc b/gr-digital/lib/digital_constellation_receiver_cb.cc
index 56385f11e6..e2b6bf1d80 100644
--- a/gr-digital/lib/digital_constellation_receiver_cb.cc
+++ b/gr-digital/lib/digital_constellation_receiver_cb.cc
@@ -40,28 +40,151 @@
digital_constellation_receiver_cb_sptr
digital_make_constellation_receiver_cb(digital_constellation_sptr constell,
- float alpha, float beta,
- float fmin, float fmax)
+ float loop_bw, float fmin, float fmax)
{
return gnuradio::get_initial_sptr(new digital_constellation_receiver_cb (constell,
- alpha, beta,
+ loop_bw,
fmin, fmax));
}
static int ios[] = {sizeof(char), sizeof(float), sizeof(float), sizeof(float)};
static std::vector<int> iosig(ios, ios+sizeof(ios)/sizeof(int));
digital_constellation_receiver_cb::digital_constellation_receiver_cb (digital_constellation_sptr constellation,
- float alpha, float beta,
- float fmin, float fmax)
+ float loop_bw, float fmin, float fmax)
: gr_block ("constellation_receiver_cb",
gr_make_io_signature (1, 1, sizeof (gr_complex)),
gr_make_io_signaturev (1, 4, iosig)),
+ d_freq(0), d_max_freq(fmax), d_min_freq(fmin), d_phase(0),
d_constellation(constellation),
- d_alpha(alpha), d_beta(beta), d_freq(0), d_max_freq(fmax), d_min_freq(fmin), d_phase(0),
d_current_const_point(0)
{
if (d_constellation->dimensionality() != 1)
throw std::runtime_error ("This receiver only works with constellations of dimension 1.");
+
+ // Set the damping factor for a critically damped system
+ d_damping = sqrtf(2.0f)/2.0f;
+
+ // Set the bandwidth, which will then call update_gains()
+ set_loop_bandwidth(loop_bw);
+}
+
+
+/*******************************************************************
+ SET FUNCTIONS
+*******************************************************************/
+
+void
+digital_constellation_receiver_cb::set_loop_bandwidth(float bw)
+{
+ if(bw < 0) {
+ throw std::out_of_range ("digital_constellation_receiver_cb: invalid bandwidth. Must be >= 0.");
+ }
+
+ d_loop_bw = bw;
+ update_gains();
+}
+
+void
+digital_constellation_receiver_cb::set_damping_factor(float df)
+{
+ if(df < 0 || df > 1.0) {
+ throw std::out_of_range ("digital_constellation_receiver_cb: invalid damping factor. Must be in [0,1].");
+ }
+
+ d_damping = df;
+ update_gains();
+}
+
+void
+digital_constellation_receiver_cb::set_alpha(float alpha)
+{
+ if(alpha < 0 || alpha > 1.0) {
+ throw std::out_of_range ("digital_constellation_receiver_cb: invalid alpha. Must be in [0,1].");
+ }
+ d_alpha = alpha;
+}
+
+void
+digital_constellation_receiver_cb::set_beta(float beta)
+{
+ if(beta < 0 || beta > 1.0) {
+ throw std::out_of_range ("digital_constellation_receiver_cb: invalid beta. Must be in [0,1].");
+ }
+ d_beta = beta;
+}
+
+void
+digital_constellation_receiver_cb::set_frequency(float freq)
+{
+ if(freq > d_max_freq)
+ d_freq = d_min_freq;
+ else if(freq < d_min_freq)
+ d_freq = d_max_freq;
+ else
+ d_freq = freq;
+}
+
+void
+digital_constellation_receiver_cb::set_phase(float phase)
+{
+ d_phase = phase;
+ while(d_phase>M_TWOPI)
+ d_phase -= M_TWOPI;
+ while(d_phase<-M_TWOPI)
+ d_phase += M_TWOPI;
+}
+
+
+/*******************************************************************
+ GET FUNCTIONS
+*******************************************************************/
+
+
+float
+digital_constellation_receiver_cb::get_loop_bandwidth() const
+{
+ return d_loop_bw;
+}
+
+float
+digital_constellation_receiver_cb::get_damping_factor() const
+{
+ return d_damping;
+}
+
+float
+digital_constellation_receiver_cb::get_alpha() const
+{
+ return d_alpha;
+}
+
+float
+digital_constellation_receiver_cb::get_beta() const
+{
+ return d_beta;
+}
+
+float
+digital_constellation_receiver_cb::get_frequency() const
+{
+ return d_freq;
+}
+
+float
+digital_constellation_receiver_cb::get_phase() const
+{
+ return d_phase;
+}
+
+/*******************************************************************
+*******************************************************************/
+
+void
+digital_constellation_receiver_cb::update_gains()
+{
+ float denom = (1.0 + 2.0*d_damping*d_loop_bw + d_loop_bw*d_loop_bw);
+ d_alpha = (4*d_damping*d_loop_bw) / denom;
+ d_beta = (4*d_loop_bw*d_loop_bw) / denom;
}
void
--
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