Revert "Merge branch 'M17_AX25_FM'"

This reverts commit e1427e3e37, reversing
changes made to bcdba292eb.

IIRDirectForm1Filter.h

@@ -1,50 +0,0 @@
-/*
- *   Copyright (C) 2015-2020 by Jonathan Naylor G4KLX
- *   Copyright (C) 2020 by Geoffrey Merck - F4FXL KC3FRA
- *
- *   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; either version 2 of the License, or
- *   (at your option) any later version.
- *
- *   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 for more details.
- *
- *   You should have received a copy of the GNU General Public License
- *   along with this program; if not, write to the Free Software
- *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
- */
-
-#if !defined(IIRDIRECTFORM1FILTER_H)
-#define	IIRDIRECTFORM1FILTER_H
-
-class CIIRDirectForm1Filter
-{
-public:
-  CIIRDirectForm1Filter(float b0, float b1, float b2, float, float a1, float a2, float additionalGaindB);
-  float filter(float sample);
-  void reset();
-
-private:
-// delay line
-  float m_x2; // x[n-2]
-  float m_y2; // y[n-2]
-  float m_x1; // x[n-1]
-  float m_y1; // y[n-1]
-  
-  // coefficients
-  // FIR
-  float m_b0;
-  float m_b1;
-  float m_b2;
-  // IIR
-  float m_a1;
-  float m_a2;
-
-  float m_additionalGainLin;
-};
-
-
-#endif