Added basic APRS transmit

Added goertzel algo
Updated binary

firmware/baseband/dsp_goertzel.cpp

@@ -0,0 +1,56 @@
+/*
+ * Copyright (C) 2014 Jared Boone, ShareBrained Technology, Inc.
+ * Copyright (C) 2018 Furrtek
+ *
+ * This file is part of PortaPack.
+ *
+ * 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, 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; see the file COPYING.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#include "dsp_goertzel.hpp"
+
+#include "complex.hpp"
+#include "sine_table.hpp"
+
+namespace dsp {
+
+GoertzelDetector::GoertzelDetector(
+	const float frequency,
+	const uint32_t sample_rate
+) {
+	coefficient = 2.0 * sin_f32((2.0 * pi * frequency / sample_rate) - pi / 2.0);
+}
+
+float GoertzelDetector::execute(
+	const buffer_s16_t& src
+) {
+
+	const size_t count = src.count;
+	
+	for (size_t i = 0; i < count; i++) {
+		s[2] = s[1];
+		s[1] = s[0];
+		s[0] = src.p[i] + coefficient * s[1] - s[2];
+	}
+
+	const uint32_t sq0 = s[0] * s[0];
+	const uint32_t sq1 = s[1] * s[1];
+	float magnitude = __builtin_sqrtf(sq0 + sq1 - s[0] * s[1] * coefficient);
+
+	return magnitude;
+}
+
+} /* namespace dsp */