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OpenAudio_ArduinoLibrary/radioNoiseBlanker_F32.h

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/* radioNoiseBlanker_F32.h
* 15 May 2020 Bob Larkin
*
* Thanks to PJRC and Pau Stoffregen for the Teensy processor, Teensyduino
* and Teensy Audio. Thanks to Chip Audette for the F32 extension
* work. Alll of that makes this possible. Bob
*
* Copyright (c) 2020 Bob Larkin
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice, development funding notice, and this permission
* notice shall be included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
/*
* An I-F signal comes in with occassional noise pulses. This block watches for
* the pulses and turns off the I-F while the pulse exists. In order to
* be as smart as possible this looks ahead by a number of samples, nAnticipation.
* Likewise, the I-F is left off for nDecay samples after the pulse ends.
* Various methods could be to be used to "turn off" the i-f,
* including replacement with waveforms.
* As of this initial write, zeros are used in the waveform.
*
* A threshold can be adjusted via setNB(). This is compared with the
* average rectified voltage being received. If this is too small, like 1.5
* or 2.0, we will be loosing data by blanking. If we set it too high, like 20.0,
* we will not blank noise pulses. Experiments will find a god setting.
* With a sine wave input and no impulse noise, the average rectified signal
* should be about 0.637. To catch the top of that requires a threshold of
* 1/0.637 = 1.57. That would seem to be a very minimal threshold setting.
*
* Status: Tested on computer data
* Functions:
* setNB( ... ); // See below
* showError(e); // e=1 means to print update() error messages
* enable(runNB); // When runNB=false the signals bypasses the update() processing
* Examples:
* TestNoiseBlanker1.ino 128 data for plotting and examination
* Time: Update() of 128 samples 32 microseconds
*/
#ifndef _radio_noise_blanker_f32_h
#define _radio_noise_blanker_f32_h
#include "AudioStream_F32.h"
#include "arm_math.h"
#define RUNNING_SUM_SIZE 125
class radioNoiseBlanker_F32 : public AudioStream_F32 {
//GUI: inputs:1, outputs:1 //this line used for automatic generation of GUI node
//GUI: shortName: NoiseBlanker
public:
// Option of AudioSettings_F32 change to block size (no sample rate dependent variables here):
radioNoiseBlanker_F32(void) : AudioStream_F32(1, inputQueueArray_f32) {
block_size = AUDIO_BLOCK_SAMPLES;
}
radioNoiseBlanker_F32(const AudioSettings_F32 &settings) : AudioStream_F32(1, inputQueueArray_f32) {
block_size = settings.audio_block_samples;
}
void enable(bool _runNB) {
runNB = _runNB;
}
void setNoiseBlanker(float32_t _threshold, uint16_t _nAnticipation, uint16_t _nDecay) {
if (_threshold < 0.0) threshold = 0.0;
else threshold = _threshold/(float32_t)RUNNING_SUM_SIZE;
if(_nAnticipation < 1) nAnticipation = 1;
else if (_nAnticipation >125) nAnticipation = 125;
else nAnticipation = _nAnticipation;
if (_nDecay < 1) nDecay = 1;
else if (_nDecay > 10) nDecay = 10; // Is this handled OK at end of block?
else nDecay = _nDecay;
}
void showError(uint16_t e) { // This is for debug
errorPrint = e;
}
void update(void);
private:
uint16_t block_size = AUDIO_BLOCK_SAMPLES;
// Input data pointers
audio_block_f32_t *inputQueueArray_f32[1];
// Control error printing in update() 0=No print
uint16_t errorPrint = 0;
// To look ahead we need a delay of up to 128 samples. Too much removes good data.
// Too little enters noise pulse data to the output. This can be a simple circular
// buffer if we make the buffer a power of 2 in length and binary-truncate the index.
// Choose 2^8 = 256.
float32_t delayData[256]; // The circular delay line
uint16_t in_index = 0; // Pointer to next block update entry
// And a mask to make the circular buffer limit to a power of 2
uint16_t delayBufferMask = 0X00FF;
// Three variables to allow .INO control of Noise Blanker
float32_t threshold = 1.0E6f; // Start disabled
uint16_t nAnticipation = 5;
uint16_t nDecay = 8;
int16_t pulseTime = -9999; // Tracks nAnticipation and nDecay
bool gateOn = true; // Signals going through NB
float32_t runningSum = 0.0;
bool runNB = false;
};
#endif