Merge pull request #946 from Brumi-2021/noise_Signal_Generator_LFSR_polynomial_of_16_32_bits

Leaving only 1 Noise signal generator GUI option , (the best one , using  LFSR polynomial of 16 bits)

firmware/application/apps/ui_siggen.hpp

@@ -48,29 +48,27 @@ private:
 	void update_tone();
 	void on_tx_progress(const uint32_t progress, const bool done);
 	
-	const std::string shape_strings[9] = {
+	const std::string shape_strings[7] = {
-		"CW          ",
+		"CW-just carrier",
-		"Sine        ",
+		"Sine signal    ",
-		"Triangle    ",
+		"Triangle signal",
-		"Saw up      ",
+		"Saw up signal  ",
-		"Saw down    ",
+		"Saw down signal",
-		"Square      ",
+		"Square signal  ",
-		"Noise n20Khz",
+		"Noise signal   "	// using 16 bits LFSR register, 16 order polynomial feedback.
-		"Noise n10khz",
-		"Noise n5khz "
 	};
 	
 	bool auto_update { false };
 	
 	Labels labels {
-		{ { 6 * 8, 4 + 10 }, "Shape:", Color::light_grey() },
+		{ { 3 * 8, 4 + 10 }, "Shape:", Color::light_grey() },
-		{ { 7 * 8, 7 * 8 }, "Tone:      Hz", Color::light_grey() },
+		{ { 6 * 8, 7 * 8 }, "Tone:      Hz", Color::light_grey() },
 		{ { 22 * 8, 15 * 8 + 4 }, "s.", Color::light_grey() },
 		{ { 8 * 8, 20 * 8 }, "Modulation: FM", Color::light_grey() }
 	};
 	
 	ImageOptionsField options_shape {
-		{ 13 * 8, 4, 32, 32 },
+		{ 10 * 8, 4, 32, 32 },
 		Color::white(),
 		Color::black(),
 		{
@@ -80,14 +78,12 @@ private:
 			{ &bitmap_sig_saw_up, 3 },
 			{ &bitmap_sig_saw_down, 4 },
 			{ &bitmap_sig_square, 5 },
-			{ &bitmap_sig_noise, 6 },
+			{ &bitmap_sig_noise, 6 }
-			{ &bitmap_sig_noise, 7 },
-			{ &bitmap_sig_noise, 8 }
 		}
 	};
 	
 	Text text_shape {
-		{ 18 * 8, 4 + 10, 8 * 8, 16 },
+		{ 15 * 8, 4 + 10, 8 * 8, 16 },
 		""
 	};
 	
@@ -98,12 +94,12 @@ private:
 	};
 	
 	Button button_update {
-		{ 6 * 8, 10 * 8, 8 * 8, 3 * 8 },
+		{ 5 * 8, 10 * 8, 8 * 8, 3 * 8 },
 		"Update"
 	};
 	
 	Checkbox checkbox_auto {
-		{ 16 * 8, 10 * 8 },
+		{ 15 * 8, 10 * 8 },
 		4,
 		"Auto"
 	};

firmware/baseband/proc_siggen.cpp

@@ -61,23 +61,29 @@ void SigGenProcessor::execute(const buffer_c8_t& buffer) {
 			} else if (tone_shape == 5) {
 				// Square
 				sample = (((tone_phase & 0xFF000000) >> 24) & 0x80) ? 127 : -128;
-			} else if (tone_shape == 6) { // taps: 6 5; feedback polynomial: x^6 + x^5 + 1 , Periode  63 = 2^n-1,it generates armonincs n x 20Khz
+			} else if (tone_shape == 6) { 	
-				// White Noise generator, pseudo random noise generator, 8 bits linear-feedback shift register (LFSR) algorithm, variant Fibonacci.
+				// Noise generator, pseudo random noise generator, 16 bits linear-feedback shift register (LFSR) algorithm, variant Fibonacci.
 				// https://en.wikipedia.org/wiki/Linear-feedback_shift_register 
-        		bit = ((lfsr >> 2) ^ (lfsr >> 3)) & 1;	
+				// 16 bits LFSR .taps: 16, 15, 13, 4 ;feedback polynomial: x^16 + x^15 + x^13 + x^4 + 1
-		   		lfsr = (lfsr >> 1) | (bit << 7);
+				// Periode 65535= 2^n-1, quite continuous .  
-           		sample = lfsr;
+				if (counter == 0) {		// we slow down the shift register, because the pseudo random noise clock freq was too high for modulator.
-			} else if (tone_shape == 7) { // taps: 7 6; feedback polynomial:  x^7 + x^6 + 1 , Periode 127 = 2^n-1,it generates armonincs n x 10Khz 
+					bit_16 = ((lfsr_16 >> 0) ^ (lfsr_16 >> 1) ^ (lfsr_16 >> 3) ^ (lfsr_16 >> 4) ^ (lfsr_16 >> 12) & 1);
-				bit = ((lfsr >> 1) ^ (lfsr >> 2)) & 1;	
+        			lfsr_16 = (lfsr_16 >> 1) | (bit_16 << 15);
-				lfsr = (lfsr >> 1) | (bit << 7);
+					sample = (lfsr_16 & 0x00FF);					  // main pseudo random noise generator. 		
-           		sample = lfsr;
+				} 
-			} else if (tone_shape == 8) { //taps:8,6,5,4;feedback polynomial: x^8 + x^6 + x^5 + x^4 + 1,Periode 255= 2^n-1, armonics  n x 5khz
+				if (counter == 5) {		// after many empiric test, that combination mix of >>4 and >>5, gives a reasonable trade off white noise / good rf power level .
-				bit = ((lfsr >> 0) ^ (lfsr >> 2) ^ (lfsr >> 3) ^ (lfsr >> 4))  & 1;	
+					sample = ((lfsr_16 & 0b0000111111110000) >> 4);   // just changing the spectrum shape .
-        		lfsr = (lfsr >> 1) | (bit << 7);
+				}
-           		sample = lfsr;
+				if (counter == 10) {
-			} 
+					sample = ((lfsr_16 & 0b0001111111100000) >> 5);   // just changing the spectrum shape .
+				}
+				counter++;
+				if (counter ==15) {	
+					counter=0; 
+				}		 
+			}
 
-			if (tone_shape < 6) 	{
+			if (tone_shape < 6) 	{  // we are in periodic signals, we need tone phases update.
 				tone_phase += tone_delta;
 			}
 			
@@ -114,8 +120,8 @@ void SigGenProcessor::on_message(const Message* const msg) {
 			fm_delta = message.bw * (0xFFFFFFULL / 1536000);
 			tone_shape = message.shape;
 			
-			// lfsr = 0x54DF0119;
+			// lfsr = seed_value ;  		// Finally not used , init lfsr 8 bits.
-			 lfsr = seed_value ;  
+			 lfsr_16 = seed_value_16;	// init lfsr 16 bits.
 
 			configured = true;
 			break;

firmware/baseband/proc_siggen.hpp

@@ -42,11 +42,14 @@ private:
 	uint8_t tone_shape { };
     uint32_t sample_count { 0 };
     bool auto_off { };
-	int32_t phase { 0 }, sphase { 0 }, delta { 0 }; 	// they may have sign .
+	int32_t phase { 0 }, sphase { 0 }, delta { 0 }; 	// they may have sign in the pseudo random sample generation.
-	int8_t  sample { 0 }, re { 0 }, im { 0 };			// they may have sign .
+	int8_t  sample { 0 }, re { 0 }, im { 0 };			// they have sign + and -.
-    uint8_t seed_value = {0x56};   						// seed : any nonzero start state will work. 
+   	uint16_t seed_value_16 = {0xACE1};					// seed 16 bits lfsr : any nonzero start state will work. 
-	uint8_t lfsr { }, bit { };  						// bit must be 8-bit to allow bit<<7 later in the code */
+	uint16_t lfsr_16 { }, bit_16 { }; 					// bit must be 16-bit to allow bit<<15 later in the code */
-	
+	uint8_t counter {0};
+	// uint8_t seed_value = {0x56}; 					// Finally not used lfsr of 8 bits , seed 8blfsr : any nonzero start state will work. 
+	// uint8_t lfsr { }, bit { };  						// Finally not used lfsr of 8 bits , bit must be 8-bit to allow bit<<7 later in the code */
+
 	TXProgressMessage txprogress_message { };
 };