diff --git a/openrtx/include/protocols/M17/M17Modulator.h b/openrtx/include/protocols/M17/M17Modulator.h
new file mode 100644
index 00000000..d64947c3
--- /dev/null
+++ b/openrtx/include/protocols/M17/M17Modulator.h
@@ -0,0 +1,115 @@
+/***************************************************************************
+ * Copyright (C) 2021 by Federico Amedeo Izzo IU2NUO, *
+ * Niccolò Izzo IU2KIN *
+ * Frederik Saraci IU2NRO *
+ * Silvano Seva IU2KWO *
+ * *
+ * 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 3 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, see *
+ ***************************************************************************/
+
+#ifndef M17_MODULATOR_H
+#define M17_MODULATOR_H
+
+#ifndef __cplusplus
+#error This header is C++ only!
+#endif
+
+#include
+#include
+
+/**
+ * Modulator device for M17 protocol.
+ */
+class M17Modulator
+{
+public:
+
+ /**
+ * Constructor.
+ */
+ M17Modulator();
+
+ /**
+ * Destructor.
+ */
+ ~M17Modulator();
+
+ /**
+ * Allocate buffers for baseband audio generation and initialise modulator.
+ */
+ void init();
+
+ /**
+ * Shutdown modulator and deallocate data buffers.
+ */
+ void terminate();
+
+ /**
+ * Generate and transmit the baseband signal obtained by 4FSK modulation of
+ * a given block of data.
+ *
+ * @param sync: synchronisation word to be prepended to data block.
+ * @param data: data block to be transmitted.
+ */
+ void send(const std::array< uint8_t, 2 >& sync,
+ const std::array< uint8_t, 46 >& data);
+
+private:
+
+ /**
+ * Generate baseband stream from symbol stream.
+ */
+ void generateBaseband();
+
+ /**
+ * Emit the baseband stream towards the output stage, platform dependent.
+ */
+ void emitBaseband();
+
+ /**
+ * Utility function to encode a given byte of data into 4FSK symbols. Each
+ * byte is encoded in four symbols.
+ *
+ * @param value: value to be encoded in 4FSK symbols.
+ * @return std::array containing the four symbols obtained by 4FSK encoding.
+ */
+ inline std::array< int8_t, 4 > byteToSymbols(uint8_t value)
+ {
+ static constexpr int8_t LUT[] = { +1, +3, -1, -3};
+ std::array< int8_t, 4 > symbols;
+
+ symbols[3] = LUT[value & 0x03];
+ value >>= 2;
+ symbols[2] = LUT[value & 0x03];
+ value >>= 2;
+ symbols[1] = LUT[value & 0x03];
+ value >>= 2;
+ symbols[0] = LUT[value & 0x03];
+
+ return symbols;
+ }
+
+ static constexpr size_t M17_RTX_SAMPLE_RATE = 48000;
+ static constexpr size_t M17_FRAME_SAMPLES = 1920;
+ static constexpr size_t M17_FRAME_SYMBOLS = 192;
+
+ using dataBuffer_t = std::array< int16_t, M17_FRAME_SAMPLES >;
+
+ std::array< int16_t, M17_FRAME_SYMBOLS > symbols;
+ int16_t *baseband_buffer; ///< Buffer for baseband audio handling.
+ dataBuffer_t *activeBuffer; ///< Half baseband buffer, in transmission.
+ dataBuffer_t *idleBuffer; ///< Half baseband buffer, free for processing.
+};
+
+#endif /* M17_MODULATOR_H */
diff --git a/openrtx/src/protocols/M17/M17Modulator.cpp b/openrtx/src/protocols/M17/M17Modulator.cpp
new file mode 100644
index 00000000..b40e5dcb
--- /dev/null
+++ b/openrtx/src/protocols/M17/M17Modulator.cpp
@@ -0,0 +1,174 @@
+/***************************************************************************
+ * Copyright (C) 2021 by Federico Amedeo Izzo IU2NUO, *
+ * Niccolò Izzo IU2KIN *
+ * Frederik Saraci IU2NRO *
+ * Silvano Seva IU2KWO *
+ * *
+ * 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 3 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, see *
+ ***************************************************************************/
+
+#include
+#include
+#include
+#include
+#include
+
+#if defined(PLATFORM_MD3x0) || defined(PLATFORM_MDUV3x0)
+#include
+#elif defined(PLATFORM_LINUX)
+#include
+#endif
+
+/*
+ * Coefficients for M17 RRC filter
+ */
+const auto rrc_taps = std::experimental::make_array
+(
+ -0.009265784007800534, -0.006136551625729697, -0.001125978562075172,
+ 0.004891777252042491, 0.01071805138282269, 0.01505751553351295,
+ 0.01679337935001369, 0.015256245142156299, 0.01042830577908502,
+ 0.003031522725559901, -0.0055333532968188165, -0.013403099825723372,
+ -0.018598682349642525, -0.01944761739590459, -0.015005271935951746,
+ -0.0053887880354343935, 0.008056525910253532, 0.022816244158307273,
+ 0.035513467692208076, 0.04244131815783876, 0.04025481153629372,
+ 0.02671818654865632, 0.0013810216516704976, -0.03394615682795165,
+ -0.07502635967975885, -0.11540977897637611, -0.14703962203941534,
+ -0.16119995609538576, -0.14969512896336504, -0.10610329539459686,
+ -0.026921412469634916, 0.08757875030779196, 0.23293327870303457,
+ 0.4006012210123992, 0.5786324696325503, 0.7528286479934068,
+ 0.908262741447522, 1.0309661131633199, 1.1095611856548013,
+ 1.1366197723675815, 1.1095611856548013, 1.0309661131633199,
+ 0.908262741447522, 0.7528286479934068, 0.5786324696325503,
+ 0.4006012210123992, 0.23293327870303457, 0.08757875030779196,
+ -0.026921412469634916, -0.10610329539459686, -0.14969512896336504,
+ -0.16119995609538576, -0.14703962203941534, -0.11540977897637611,
+ -0.07502635967975885, -0.03394615682795165, 0.0013810216516704976,
+ 0.02671818654865632, 0.04025481153629372, 0.04244131815783876,
+ 0.035513467692208076, 0.022816244158307273, 0.008056525910253532,
+ -0.0053887880354343935, -0.015005271935951746, -0.01944761739590459,
+ -0.018598682349642525, -0.013403099825723372, -0.0055333532968188165,
+ 0.003031522725559901, 0.01042830577908502, 0.015256245142156299,
+ 0.01679337935001369, 0.01505751553351295, 0.01071805138282269,
+ 0.004891777252042491, -0.001125978562075172, -0.006136551625729697,
+ -0.009265784007800534
+);
+
+/*
+ * FIR implementation of the RRC filter for baseband audio generation.
+ */
+static Fir< std::tuple_size< decltype(rrc_taps) >::value > rrc(rrc_taps);
+
+
+M17Modulator::M17Modulator()
+{
+
+}
+
+M17Modulator::~M17Modulator()
+{
+ terminate();
+}
+
+void M17Modulator::init()
+{
+ /*
+ * Allocate a chunk of memory to contain two complete buffers for baseband
+ * audio. Split this chunk in two separate blocks for double buffering using
+ * placement new.
+ */
+
+ baseband_buffer = new int16_t[2 * M17_FRAME_SAMPLES];
+ activeBuffer = new (baseband_buffer) dataBuffer_t;
+ int16_t *ptr = baseband_buffer + activeBuffer->size();
+ idleBuffer = new (ptr) dataBuffer_t;
+}
+
+void M17Modulator::terminate()
+{
+ // Delete the buffers and deallocate memory.
+ activeBuffer->~dataBuffer_t();
+ idleBuffer->~dataBuffer_t();
+ delete[] baseband_buffer;
+}
+
+void M17Modulator::send(const std::array< uint8_t, 2 >& sync,
+ const std::array< uint8_t, 46 >& data)
+{
+ auto sync1 = byteToSymbols(sync[0]);
+ auto sync2 = byteToSymbols(sync[1]);
+
+ auto it = std::copy(sync1.begin(), sync1.end(), symbols.begin());
+ it = std::copy(sync2.begin(), sync2.end(), it);
+
+ for(size_t i = 0; i < data.size(); i++)
+ {
+ auto sym = byteToSymbols(data[i]);
+ it = std::copy(sym.begin(), sym.end(), it);
+ }
+
+ generateBaseband();
+ emitBaseband();
+}
+
+void M17Modulator::generateBaseband()
+{
+ idleBuffer->fill(0);
+ for(size_t i = 0; i < symbols.size(); i++)
+ {
+ idleBuffer->at(i * 10) = symbols[i];
+ }
+
+ for(size_t i = 0; i < idleBuffer->size(); i++)
+ {
+ float elem = static_cast< float >(idleBuffer->at(i));
+ idleBuffer->at(i) = static_cast< int16_t >(rrc(elem) * 7168.0);
+ }
+}
+
+#if defined(PLATFORM_MD3x0) || defined(PLATFORM_MDUV3x0)
+void M17Modulator::emitBaseband()
+{
+ dsp_pwmCompensate(idleBuffer->data(), idleBuffer->size());
+ dsp_invertPhase(idleBuffer->data(), idleBuffer->size());
+
+ for(size_t i = 0; i < M17_FRAME_SAMPLES; i++)
+ {
+ int32_t pos_sample = idleBuffer->at(i) + 32768;
+ uint16_t shifted_sample = pos_sample >> 8;
+ idleBuffer->at(i) = shifted_sample;
+ }
+
+ toneGen_waitForStreamEnd();
+ std::swap(idleBuffer, activeBuffer);
+
+ toneGen_playAudioStream(reinterpret_cast< uint16_t *>(activeBuffer->data()),
+ activeBuffer->size(), M17_RTX_SAMPLE_RATE);
+}
+#elif defined(PLATFORM_LINUX)
+void M17Modulator::emitBaseband()
+{
+ std::swap(idleBuffer, activeBuffer);
+
+ FILE *outfile = fopen("/tmp/m17_output.raw", "ab");
+
+ for(auto s : *activeBuffer)
+ {
+ fwrite(&s, sizeof(s), 1, outfile);
+ }
+
+ fclose(outfile);
+}
+#else
+void M17Modulator::emitBaseband() { }
+#endif