Transceiver52M: Update noise measurement calculation

Previous removal of the energy detector requirement broke
the noise level calculation loop. The previous adaptive
approach was finicky - noticably at high gain levels. Since
we no longer use the energy threshold for primary burst gating,
we can return to a simpler world.

In the new approach, we compute a running average of energy
levels and track them with a noise vector. A timeslot that
passes the correlator threshold is a valid burst. These are
not used in the noise calculation. Everything else is
considered noise and used to compute the noise level with
respect to full scale input level, which for almost all
supported devices is 2^15.

Signed-off-by: Thomas Tsou <tom@tsou.cc>

1 files changed, 29 insertions, 0 deletions

diff --git a/Transceiver52M/radioVector.cpp b/Transceiver52M/radioVector.cpp
index f20d97a..043effa 100644
--- a/Transceiver52M/radioVector.cpp
+++ b/Transceiver52M/radioVector.cpp
@@ -41,6 +41,35 @@ bool radioVector::operator>(const radioVector& other) const
 	return mTime > other.mTime;
 }
 
+noiseVector::noiseVector(size_t n)
+{
+	this->resize(n);
+	it = this->begin();
+}
+
+float noiseVector::avg()
+{
+	float val = 0.0;
+
+	for (int i = 0; i < size(); i++)
+		val += (*this)[i];
+
+	return val / (float) size();
+}
+
+bool noiseVector::insert(float val)
+{
+	if (!size())
+		return false;
+
+	if (it == this->end())
+		it = this->begin();
+
+	*it++ = val;
+
+	return true;
+}
+
 unsigned VectorFIFO::size()
 {
 	return mQ.size();