Change baseband floats to normalize at +/-1.0.

firmware/baseband/audio_compressor.cpp

@@ -40,8 +40,7 @@ float GainComputer::operator()(const float x) const {
 void FeedForwardCompressor::execute_in_place(const buffer_f32_t& buffer) {
 	constexpr float makeup_gain = std::pow(10.0f, (threshold - (threshold / ratio)) / -20.0f);
 	for(size_t i=0; i<buffer.count; i++) {
-		// TODO: Terrible hack here due to not normalizing float samples to +/-1.0.
+		buffer.p[i] = execute_once(buffer.p[i]) * makeup_gain;
-		buffer.p[i] = execute_once(buffer.p[i] * (1.0f / 32768.0f)) * (makeup_gain * 32768.0f);
 	}
 }
 

firmware/baseband/audio_output.cpp

@@ -46,7 +46,7 @@ void AudioOutput::write(
 ) {
 	std::array<float, 32> audio_f;
 	for(size_t i=0; i<audio.count; i++) {
-		audio_f[i] = audio.p[i];
+		audio_f[i] = audio.p[i] * ki;
 	}
 	write(buffer_f32_t {
 		audio_f.data(),
@@ -89,7 +89,7 @@ void AudioOutput::on_block(
 void AudioOutput::fill_audio_buffer(const buffer_f32_t& audio) {
 	auto audio_buffer = audio::dma::tx_empty_buffer();
 	for(size_t i=0; i<audio_buffer.count; i++) {
-		const int32_t sample_int = audio.p[i];
+		const int32_t sample_int = audio.p[i] * k;
 		const int32_t sample_saturated = __SSAT(sample_int, 16);
 		audio_buffer.p[i].left = audio_buffer.p[i].right = sample_saturated;
 	}

firmware/baseband/audio_output.hpp

@@ -44,6 +44,9 @@ public:
 	void write(const buffer_f32_t& audio);
 
 private:
+	static constexpr float k = 32768.0f;
+	static constexpr float ki = 1.0f / k;
+
 	BlockDecimator<float, 32> block_buffer { 1 };	
 
 	IIRBiquadFilter hpf;

firmware/baseband/audio_stats_collector.cpp

@@ -42,8 +42,8 @@ bool AudioStatsCollector::update_stats(const size_t sample_count, const size_t s
 	const size_t samples_per_update = sampling_rate * update_interval;
 
 	if( count >= samples_per_update ) {
-		statistics.rms_db = complex16_mag_squared_to_dbv_norm(squared_sum / count);
+		statistics.rms_db = mag2_to_dbv_norm(squared_sum / count);
-		statistics.max_db = complex16_mag_squared_to_dbv_norm(max_squared);
+		statistics.max_db = mag2_to_dbv_norm(max_squared);
 		statistics.count = count;
 
 		squared_sum = 0;

firmware/baseband/channel_stats_collector.hpp

@@ -49,7 +49,7 @@ public:
 
 		if( count >= samples_per_update ) {
 			const float max_squared_f = max_squared;
-			const int32_t max_db = complex16_mag_squared_to_dbv_norm(max_squared_f);
+			const int32_t max_db = mag2_to_dbv_norm(max_squared_f * (1.0f / (32768.0f * 32768.0f)));
 			callback({ max_db, count });
 
 			max_squared = 0;

firmware/baseband/dsp_demodulate.cpp

@@ -42,8 +42,8 @@ buffer_f32_t AM::execute(
 		const uint32_t sample1 = *__SIMD32(src_p)++;
 		const uint32_t mag_sq0 = __SMUAD(sample0, sample0);
 		const uint32_t mag_sq1 = __SMUAD(sample1, sample1);
-		*(dst_p++) = __builtin_sqrtf(mag_sq0);
+		*(dst_p++) = __builtin_sqrtf(mag_sq0) * k;
-		*(dst_p++) = __builtin_sqrtf(mag_sq1);
+		*(dst_p++) = __builtin_sqrtf(mag_sq1) * k;
 	}
 
 	return { dst.p, src.count, src.sampling_rate };
@@ -57,10 +57,10 @@ buffer_f32_t SSB::execute(
 	const auto src_end = &src.p[src.count];
 	auto dst_p = dst.p;
 	while(src_p < src_end) {
-		*(dst_p++) = (src_p++)->real();
+		*(dst_p++) = (src_p++)->real() * k;
-		*(dst_p++) = (src_p++)->real();
+		*(dst_p++) = (src_p++)->real() * k;
-		*(dst_p++) = (src_p++)->real();
+		*(dst_p++) = (src_p++)->real() * k;
-		*(dst_p++) = (src_p++)->real();
+		*(dst_p++) = (src_p++)->real() * k;
 	}
 
 	return { dst.p, src.count, src.sampling_rate };
@@ -99,8 +99,8 @@ buffer_f32_t FM::execute(
 		const auto t0 = multiply_conjugate_s16_s32(s0, z);
 		const auto t1 = multiply_conjugate_s16_s32(s1, s0);
 		z = s1;
-		*(dst_p++) = angle_precise(t0) * k;
+		*(dst_p++) = angle_precise(t0) * kf;
-		*(dst_p++) = angle_precise(t1) * k;
+		*(dst_p++) = angle_precise(t1) * kf;
 	}
 	z_ = z;
 
@@ -122,9 +122,9 @@ buffer_s16_t FM::execute(
 		const auto t0 = multiply_conjugate_s16_s32(s0, z);
 		const auto t1 = multiply_conjugate_s16_s32(s1, s0);
 		z = s1;
-		const int32_t theta0_int = angle_approx_0deg27(t0) * k;
+		const int32_t theta0_int = angle_approx_0deg27(t0) * ks16;
 		const int32_t theta0_sat = __SSAT(theta0_int, 16);
-		const int32_t theta1_int = angle_approx_0deg27(t1) * k;
+		const int32_t theta1_int = angle_approx_0deg27(t1) * ks16;
 		const int32_t theta1_sat = __SSAT(theta1_int, 16);
 		*__SIMD32(dst_p)++ = __PKHBT(
 			theta0_sat,
@@ -143,7 +143,8 @@ void FM::configure(const float sampling_rate, const float deviation_hz) {
 	 * Maximum delta-theta (output of atan2) at maximum deviation frequency:
 	 * delta_theta_max = 2 * pi * deviation / sampling_rate
 	 */
-	k = static_cast<float>(32767.0f / (2.0 * pi * deviation_hz / sampling_rate));
+	kf = static_cast<float>(1.0f / (2.0 * pi * deviation_hz / sampling_rate));
+	ks16 = 32767.0f * kf;
 }
 
 }

firmware/baseband/dsp_demodulate.hpp

@@ -33,6 +33,9 @@ public:
 		const buffer_c16_t& src,
 		const buffer_f32_t& dst
 	);
+
+private:
+	static constexpr float k = 1.0f / 32768.0f;
 };
 
 class SSB {
@@ -41,6 +44,9 @@ public:
 		const buffer_c16_t& src,
 		const buffer_f32_t& dst
 	);
+
+private:
+	static constexpr float k = 1.0f / 32768.0f;
 };
 
 class FM {
@@ -59,7 +65,8 @@ public:
 
 private:
 	complex16_t::rep_type z_ { 0 };
-	float k { 0 };
+	float kf { 0 };
+	float ks16 { 0 };
 };
 
 } /* namespace demodulate */

firmware/baseband/spectrum_collector.cpp

@@ -117,8 +117,8 @@ void SpectrumCollector::update() {
 			// Three point Hamming window.
 			const auto corrected_sample = channel_spectrum[i] * 0.54f
 				+ (channel_spectrum[(i-1) & 0xff] + channel_spectrum[(i+1) & 0xff]) * -0.23f;
-			const auto mag2 = magnitude_squared(corrected_sample);
+			const auto mag2 = magnitude_squared(corrected_sample * (1.0f / 32768.0f));
-			const float db = complex16_mag_squared_to_dbv_norm(mag2);
+			const float db = mag2_to_dbv_norm(mag2);
 			constexpr float mag_scale = 5.0f;
 			const unsigned int v = (db * mag_scale) + 255.0f;
 			spectrum.db[i] = std::max(0U, std::min(255U, v));

firmware/common/utility.cpp

@@ -82,15 +82,14 @@ float fast_pow2(const float val) {
 	return u.f;
 }
 
-float complex16_mag_squared_to_dbv_norm(const float c16_mag_squared) {
+float mag2_to_dbv_norm(const float mag2) {
-	constexpr float input_component_max = 32768;
+	constexpr float mag2_max = 1.0f;
-	constexpr float mag2_max = (input_component_max * input_component_max) * 2;
 	constexpr float mag2_log2_max = std::log2(mag2_max);
 	constexpr float log_mag2_mag_factor = 0.5f;
 	constexpr float log2_log10_factor = std::log10(2.0f);
 	constexpr float log10_dbv_factor = 20.0f;
 	constexpr float mag2_to_db_factor = log_mag2_mag_factor * log2_log10_factor * log10_dbv_factor;
-	return (fast_log2(c16_mag_squared) - mag2_log2_max) * mag2_to_db_factor;
+	return (fast_log2(mag2) - mag2_log2_max) * mag2_to_db_factor;
 }
 
 /* GCD implementation derived from recursive implementation at

firmware/common/utility.hpp

@@ -72,7 +72,7 @@ constexpr size_t log_2(const size_t n, const size_t p = 0) {
 float fast_log2(const float val);
 float fast_pow2(const float val);
 
-float complex16_mag_squared_to_dbv_norm(const float c16_mag_squared);
+float mag2_to_dbv_norm(const float mag2);
 
 inline float magnitude_squared(const std::complex<float> c) {
 	const auto r = c.real();