diff --git a/sdrbase/CMakeLists.txt b/sdrbase/CMakeLists.txt
index 9a55e6dd8..0459c898c 100644
--- a/sdrbase/CMakeLists.txt
+++ b/sdrbase/CMakeLists.txt
@@ -40,6 +40,7 @@ set(sdrbase_SOURCES
dsp/nco.cpp
dsp/ncof.cpp
dsp/phaselock.cpp
+ dsp/phaselockcomplex.cpp
dsp/projector.cpp
dsp/samplesinkfifo.cpp
dsp/samplesourcefifo.cpp
@@ -146,6 +147,7 @@ set(sdrbase_HEADERS
dsp/ncof.h
dsp/phasediscri.h
dsp/phaselock.h
+ dsp/phaselockcomplex.h
dsp/projector.h
dsp/recursivefilters.h
dsp/samplesinkfifo.h
diff --git a/sdrbase/dsp/phaselockcomplex.cpp b/sdrbase/dsp/phaselockcomplex.cpp
new file mode 100644
index 000000000..1fedb512d
--- /dev/null
+++ b/sdrbase/dsp/phaselockcomplex.cpp
@@ -0,0 +1,137 @@
+///////////////////////////////////////////////////////////////////////////////////
+// Copyright (C) 2018 F4EXB //
+// written by Edouard Griffiths //
+// //
+// See: http://liquidsdr.org/blog/pll-howto/ //
+// Fixes filter registers saturation //
+// //
+// This program 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 as version 3 of the License, or //
+// //
+// This program 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 V3 for more details. //
+// //
+// You should have received a copy of the GNU General Public License //
+// along with this program. If not, see . //
+///////////////////////////////////////////////////////////////////////////////////
+
+#include
+#include
+#include "phaselockcomplex.h"
+
+PhaseLockComplex::PhaseLockComplex() :
+ m_a1(1.0),
+ m_a2(1.0),
+ m_b0(1.0),
+ m_b1(1.0),
+ m_b2(1.0),
+ m_v0(0.0),
+ m_v1(0.0),
+ m_v2(0.0),
+ m_deltaPhi(0.0),
+ m_phiHatLast(0.0),
+ m_phiHat(0.0),
+ m_y(1.0, 0.0),
+ m_yRe(1.0),
+ m_yIm(0.0),
+ m_freq(0.0)
+{
+}
+
+void PhaseLockComplex::computeCoefficients(Real wn, Real zeta, Real K)
+{
+ double t1 = K/(wn*wn); //
+ double t2 = 2*zeta/wn - 1/K; //
+
+ double b0 = 2*K*(1.+t2/2.0f);
+ double b1 = 2*K*2.;
+ double b2 = 2*K*(1.-t2/2.0f);
+
+ double a0 = 1 + t1/2.0f;
+ double a1 = -t1;
+ double a2 = -1 + t1/2.0f;
+
+ qDebug("PhaseLockComplex::computeCoefficients: b_raw: %f %f %f", b0, b1, b2);
+ qDebug("PhaseLockComplex::computeCoefficients: a_raw: %f %f %f", a0, a1, a2);
+
+ m_b0 = b0 / a0;
+ m_b1 = b1 / a0;
+ m_b2 = b2 / a0;
+
+ // a0 = 1.0 is implied
+ m_a1 = a1 / a0;
+ m_a2 = a2 / a0;
+
+ qDebug("PhaseLockComplex::computeCoefficients: b: %f %f %f", m_b0, m_b1, m_b2);
+ qDebug("PhaseLockComplex::computeCoefficients: a: 1.0 %f %f", m_a1, m_a2);
+
+ reset();
+}
+
+void PhaseLockComplex::reset()
+{
+ // reset filter accumulators and phase
+ m_v0 = 0.0f;
+ m_v1 = 0.0f;
+ m_v2 = 0.0f;
+ m_deltaPhi = 0.0f;
+ m_phiHatLast = 0.0f;
+ m_phiHat = 0.0f;
+ m_y.real(1.0);
+ m_y.real(0.0);
+ m_yRe = 1.0f;
+ m_yIm = 0.0f;
+ m_freq = 0.0f;
+}
+
+void PhaseLockComplex::feed(float re, float im)
+{
+ m_yRe = cos(m_phiHat);
+ m_yIm = sin(m_phiHat);
+ m_y.real(m_yRe);
+ m_y.imag(m_yIm);
+ std::complex x(re, im);
+ m_deltaPhi = std::arg(x * std::conj(m_y));
+
+ // advance buffer
+ m_v2 = m_v1; // shift center register to upper register
+ m_v1 = m_v0; // shift lower register to center register
+
+ // compute new lower register
+ m_v0 = m_deltaPhi - m_v1*m_a1 - m_v2*m_a2;
+
+ // compute new output
+ m_phiHat = m_v0*m_b0 + m_v1*m_b1 + m_v2*m_b2;
+
+ // prevent saturation
+ if (m_phiHat > 2.0*M_PI)
+ {
+ m_v0 *= (m_phiHat - 2.0*M_PI) / m_phiHat;
+ m_v1 *= (m_phiHat - 2.0*M_PI) / m_phiHat;
+ m_v2 *= (m_phiHat - 2.0*M_PI) / m_phiHat;
+ m_phiHat -= 2.0*M_PI;
+ }
+
+ if (m_phiHat < -2.0*M_PI)
+ {
+ m_v0 *= (m_phiHat + 2.0*M_PI) / m_phiHat;
+ m_v1 *= (m_phiHat + 2.0*M_PI) / m_phiHat;
+ m_v2 *= (m_phiHat + 2.0*M_PI) / m_phiHat;
+ m_phiHat += 2.0*M_PI;
+ }
+
+ m_freq = (m_phiHat - m_phiHatLast) / (2.0*M_PI);
+
+ if (m_freq < -1.0f) {
+ m_freq += 2.0f;
+ } else if (m_freq > 1.0f) {
+ m_freq -= 2.0f;
+ }
+
+ m_phiHatLast = m_phiHat;
+}
+
+
diff --git a/sdrbase/dsp/phaselockcomplex.h b/sdrbase/dsp/phaselockcomplex.h
new file mode 100644
index 000000000..de5479c51
--- /dev/null
+++ b/sdrbase/dsp/phaselockcomplex.h
@@ -0,0 +1,70 @@
+///////////////////////////////////////////////////////////////////////////////////
+// Copyright (C) 2018 F4EXB //
+// written by Edouard Griffiths //
+// //
+// See: http://liquidsdr.org/blog/pll-howto/ //
+// Fixes filter registers saturation //
+// //
+// This program 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 as version 3 of the License, or //
+// //
+// This program 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 V3 for more details. //
+// //
+// You should have received a copy of the GNU General Public License //
+// along with this program. If not, see . //
+///////////////////////////////////////////////////////////////////////////////////
+
+#ifndef SDRBASE_DSP_PHASELOCKCOMPLEX_H_
+#define SDRBASE_DSP_PHASELOCKCOMPLEX_H_
+
+#include "dsp/dsptypes.h"
+#include "export.h"
+
+/** General purpose Phase-locked loop using complex analytic signal input. */
+class SDRBASE_API PhaseLockComplex
+{
+public:
+ PhaseLockComplex();
+ /** Compute loop filter parameters (active PI design)
+ * \param wn PLL bandwidth relative to Nyquist frequency
+ * \param zeta PLL damping factor
+ * \param K PLL loop gain
+ * */
+ void computeCoefficients(Real wn, Real zeta, Real K);
+ void reset();
+ void feed(float re, float im);
+ const std::complex& getComplex() const { return m_y; }
+ float getReal() const { return m_yRe; }
+ float getImag() const { return m_yIm; }
+ bool locked() const { return (m_deltaPhi > -0.1) && (m_deltaPhi < 0.1); }
+ float getFrequency() const { return m_freq; }
+ float getDeltaPhi() const { return m_deltaPhi; }
+ float getPhiHat() const { return m_phiHat; }
+
+private:
+ // a0 = 1 is implied
+ float m_a1;
+ float m_a2;
+ float m_b0;
+ float m_b1;
+ float m_b2;
+ float m_v0;
+ float m_v1;
+ float m_v2;
+ float m_deltaPhi;
+ float m_phiHatLast;
+ float m_phiHat;
+ std::complex m_y;
+ float m_yRe;
+ float m_yIm;
+ float m_freq;
+
+};
+
+
+
+#endif /* SDRBASE_DSP_PHASELOCKCOMPLEX_H_ */