Git-Mirrors/portapack-mayhem
1
0
Fork 0
mirror of https://github.com/eried/portapack-mayhem.git synced 2025-08-01 11:06:30 -04:00
Code Issues Projects Releases Packages Wiki Activity

Finally Noise Signal with best option 16 bit LFSR

Browse source
This commit is contained in:
Brumi-2021 2023-05-02 21:29:35 +02:00
parent 804fa0d3c4
commit d77102426a
3 changed files with 26 additions and 30 deletions
Download patch file Download diff file Expand all files Collapse all files

32
firmware/baseband/proc_siggen.cpp
View file

@ -61,21 +61,9 @@ 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
// White Noise generator, pseudo random noise generator, 8 bits linear-feedback shift register (LFSR) algorithm, variant Fibonacci.
} else if (tone_shape == 6) { // White Noise generator, pseudo random noise generator, 8 bits linear-feedback shift register (LFSR) algorithm, variant Fibonacci.
// https://en.wikipedia.org/wiki/Linear-feedback_shift_register
bit = ((lfsr >> 2) ^ (lfsr >> 3)) & 1;
lfsr = (lfsr >> 1) | (bit << 7);
sample = lfsr;
} 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 = ((lfsr >> 1) ^ (lfsr >> 2)) & 1;
lfsr = (lfsr >> 1) | (bit << 7);
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
bit = ((lfsr >> 0) ^ (lfsr >> 2) ^ (lfsr >> 3) ^ (lfsr >> 4)) & 1;
lfsr = (lfsr >> 1) | (bit << 7);
sample = lfsr;
} else if (tone_shape == 9) { // 16 bits LFSR .taps: 16, 15, 13, 4 ;feedback polynomial: x^16 + x^15 + x^13 + x^4 + 1
// 16 bits LFSR .taps: 16, 15, 13, 4 ;feedback polynomial: x^16 + x^15 + x^13 + x^4 + 1
// Periode 65535= 2^n-1, harmonics every < 1Khz , quite continuous .
if (counter == 0) {
bit_16 = ((lfsr_16 >> 0) ^ (lfsr_16 >> 1) ^ (lfsr_16 >> 3) ^ (lfsr_16 >> 4) ^ (lfsr_16 >> 12) & 1);
@ -87,6 +75,20 @@ void SigGenProcessor::execute(const buffer_c8_t& buffer) {
counter = 0;
}
}
/* else if (tone_shape == 7) { // 8 bit options, finally not used-
bit = ((lfsr >> 2) ^ (lfsr >> 3)) & 1; // taps: 6 5; feedback polynomial: x^6 + x^5 + 1 , Periode 63 = 2^n-1,it generates armonincs n x 20Khz
lfsr = (lfsr >> 1) | (bit << 7);
sample = lfsr;
} else if (tone_shape == 8) { // taps: 7 6; feedback polynomial: x^7 + x^6 + 1 , Periode 127 = 2^n-1,it generates armonincs n x 10Khz
bit = ((lfsr >> 1) ^ (lfsr >> 2)) & 1;
lfsr = (lfsr >> 1) | (bit << 7);
sample = lfsr;
} else if (tone_shape == 9) { //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
bit = ((lfsr >> 0) ^ (lfsr >> 2) ^ (lfsr >> 3) ^ (lfsr >> 4)) & 1;
lfsr = (lfsr >> 1) | (bit << 7);
sample = lfsr; } */
if (tone_shape < 6) {
tone_phase += tone_delta;
@ -125,7 +127,7 @@ void SigGenProcessor::on_message(const Message* const msg) {
fm_delta = message.bw * (0xFFFFFFULL / 1536000);
tone_shape = message.shape;
lfsr = seed_value ; // init lfsr 8 bits.
// lfsr = seed_value ; // Finally not used , init lfsr 8 bits.
lfsr_16 = seed_value_16; // init lfsr 16 bits.
configured = true;