From d7f5f09cb863d42d244b017baef04f6bf4c502f9 Mon Sep 17 00:00:00 2001
From: Jens Ahrensfeld <jens@jayfield.org>
Date: Wed, 9 Jan 2019 10:32:32 +0000
Subject: [PATCH] - use time constant for DC calculation - use time constant
 for Min/Max calculation - added AGC

git-svn-id: http://moon:8086/svn/software/trunk/projects/GnuRadio@394 b431acfa-c32f-4a4a-93f1-934dc6c82436
---
 gr-jay/lib/garage_impl.cc | 30 ++++++++++++++++++++----------
 gr-jay/lib/garage_impl.h  |  1 +
 2 files changed, 21 insertions(+), 10 deletions(-)

diff --git a/gr-jay/lib/garage_impl.cc b/gr-jay/lib/garage_impl.cc
index 7232ef0..4396e55 100644
--- a/gr-jay/lib/garage_impl.cc
+++ b/gr-jay/lib/garage_impl.cc
@@ -56,6 +56,7 @@ garage_impl::garage_impl(int sampleRate, int samplesPerSym, float kLoopFilter, f
 , m_vmax(0)
 , m_v_sig(0)
 , m_dc_corr(0)
+, m_agc_gain(1.0f)
 , m_lag_accu(0)
 , m_id_accu(0)
 , m_id_bit(0)
@@ -118,14 +119,19 @@ int garage_impl::general_work (int noutput_items, gr_vector_int &ninput_items, g
 	
 	// Do <+signal processing+>
 	int countReload = m_samplesPerSym-1;
-	float alpha_thr = 0.002f;
-	float hyst_thr = 0.1f;
+	const float alpha_thr = 0.01f;
+	const float alpha_dc = 0.002f;
+	const float hyst_thr = 0.1f;
+	const float agc_mu = 0.01f;
+	const float agc_target = 0.5f;
+	const float agc_gain_max = 10.0f;
+	const float k_lead = 1.0e-1f;
+	const float k_lag = 1.0e-4f;
+	const float rho_leak = 0.9999;
+
+	float err = 0;
 	float k_leadLag = m_kLoopFilter;
 	float loopThreshold = m_kThreshold;
-	float k_lead = 1.0e-1f;
-	float k_lag = 1.0e-4f;
-	float rho_leak = 0.9999;
-	float err = 0;
 	
 	float alpha_sig = 0.5f/m_samplesPerSym;
 	
@@ -134,22 +140,26 @@ int garage_impl::general_work (int noutput_items, gr_vector_int &ninput_items, g
 	{
 		// Get next interpolated sample
 		float i_f = m_i - (float)i_i;
-		float y = (1.f-i_f)*in[i_i] + i_f*in[i_i+1] - m_dc_corr;
+		float y = m_agc_gain * ((1.f-i_f)*in[i_i] + i_f*in[i_i+1] - m_dc_corr);
 		
 		// Calculate threshold
 		m_vmin *= rho;
 		m_vmax *= rho;
 		if (y < m_vmin)
 		{
-			m_vmin = y;
+			m_vmin = (1-alpha_thr)*m_vmin + alpha_thr*y;
 		}
 		else if (y > m_vmax)
 		{
-			m_vmax = y;
+			m_vmax = (1-alpha_thr)*m_vmax + alpha_thr*y;
 		}
 
+		// AGC
+		float agc_err = m_vmax - agc_target;
+		m_agc_gain = std::max(0.0f, std::min(agc_gain_max, m_agc_gain - agc_mu*agc_err));
+		
 		// Calculate DC offset correction
-		m_dc_corr += alpha_thr*(m_vmax + m_vmin);
+		m_dc_corr = (1-alpha_dc)*m_dc_corr + alpha_dc*(m_vmax + m_vmin);
 		
 		// Signal detection
 		float yd = std::abs(y)-m_vmax;
diff --git a/gr-jay/lib/garage_impl.h b/gr-jay/lib/garage_impl.h
index cde8dcb..9fe1cc9 100644
--- a/gr-jay/lib/garage_impl.h
+++ b/gr-jay/lib/garage_impl.h
@@ -42,6 +42,7 @@ class garage_impl : public garage
         float m_vmax;
         float m_v_sig;
         float m_dc_corr;
+		float m_agc_gain;
         float m_lag_accu;
         float m_id_accu;
         int m_id_bit;