BFM demod: apply de-emphasis

2026-06-05 07:24:44 -04:00 · 2015-12-08 02:00:30 +01:00
parent 2f8fda7137
commit e533997dbe
6 changed files with 138 additions and 22 deletions
@@ -0,0 +1,50 @@
+///////////////////////////////////////////////////////////////////////////////////
+// Copyright (C) 2015 F4EXB                                                      //
+// written by Edouard Griffiths                                                  //
+//                                                                               //
+// 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 <http://www.gnu.org/licenses/>.          //
+///////////////////////////////////////////////////////////////////////////////////
+
+#ifndef INCLUDE_DSP_FILTERRC_H_
+#define INCLUDE_DSP_FILTERRC_H_
+
+#include "dsp/dsptypes.h"
+
+/** First order low-pass IIR filter for real-valued signals. */
+class LowPassFilterRC
+{
+public:
+
+    /**
+     * Construct 1st order low-pass IIR filter.
+     *
+     * timeconst :: RC time constant in seconds (1 / (2 * PI * cutoff_freq)
+     */
+    LowPassFilterRC(Real timeconst);
+
+    /**
+     * Reconfigure filter with new time constant
+     */
+    void configure(Real timeout);
+
+    /** Process samples. */
+    void process(const Real& sample_in, Real& sample_out);
+
+private:
+    Real m_timeconst;
+    Real m_y1;
+    Real m_a1;
+    Real m_b0;
+};
+
+#endif /* INCLUDE_DSP_FILTERRC_H_ */