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RadioIQMixer_F32.h
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RadioIQMixer_F32.h
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/*
* RadioIQMixer_F32.h
*
* 8 April 2020 Bob Larkin
* With much credit to:
* Chip Audette (OpenAudio) Feb 2017
* and of course, to PJRC for the Teensy and Teensy Audio Library
*
* This quadrature mixer block is suitable for both transmit and receive.
*
* A basic building block is a pair of mixers with the
* LO going to the mixers at the same frequency, but differing in phase
* by 90 degrees. This provides two outputs I and Q that are offset in
* frequency but also 90 degrees apart in phase. The LO are included
* in the block, but there are no post-mixing filters.
*
* The frequency is set by .frequency(float freq_Hz)
* There is provision for varying
* the phase between the sine and cosine oscillators. Technically this is no
* longer sin and cos, but that is what real hardware needs.
*
* The amplitudeC(a) allows balancing of I and Q channels.
*
* The output levels are 0.5 times the input level, unless adjusted by
* gainOut(g).
*
* Status: Tested in doSimple==1
* Tested in FineFreqShift_OA.ino, T3.6 and T4.0
*
* Inputs: 0 is signal
* Outputs: 0 is I 1 is Q
*
* Functions, available during operation:
* void frequency(float32_t fr) Sets LO frequency Hz
* void iqmPhaseS(float32_t ps) Sets Phase of Sine in radians
* void phaseS_C_r(float32_t pc) Sets relative phase of Cosine in radians, approximately pi/2
* void amplitudeC(float32_t a) Sets relative amplitude of I output
* void useSimple(bool s) Faster if 1, but no phase/amplitude adjustment
* void setSampleRate_Hz(float32_t fs_Hz) Allows dynamic sample rate change for this function
* void useTwoChannel(bool 2Ch) Uses 2 input cannels, I & Q, if true. Apr 2021
* void setGainOut(float32_t gainO) Sets gain after mixers. Often a value of 2.0 makes the
* block lossless. For both doSimple and not doSimple.
*
* Time: T3.6 For an update of a 128 sample block, doSimple=true, 46 microseconds
* T4.0 For an update of a 128 sample block, doSimple=true, 20 microseconds
*
* Rev Apr2021 Allowed for 2-channel I-Q input. Defaults to 1 Channel. "real."
* Rev 30Jan23 Corrected setSampleRate_Hz(sr) to do so! RSL
* Rev 2 Feb 2023 Added gainOut, with or without doSimple. RSL
*/
#ifndef _radioIQMixer_f32_h
#define _radioIQMixer_f32_h
#include "AudioStream_F32.h"
#include "arm_math.h"
#include "mathDSP_F32.h"
class RadioIQMixer_F32 : public AudioStream_F32 {
//GUI: inputs:2, outputs:2 //this line used for automatic generation of GUI node
//GUI: shortName: IQMixer
public:
// Option of AudioSettings_F32 change to block size or sample rate:
RadioIQMixer_F32(void) : AudioStream_F32(2, inputQueueArray_f32) {
// Defaults
}
RadioIQMixer_F32(const AudioSettings_F32 &settings) : AudioStream_F32(2, inputQueueArray_f32) {
setSampleRate_Hz(settings.sample_rate_Hz);
block_size = settings.audio_block_samples;
}
void frequency(float32_t fr) { // LO Frequency in Hz
freq = fr;
if (freq < 0.0f) freq = 0.0f;
else if (freq > sample_rate_Hz/2.0f) freq = sample_rate_Hz/2.0f;
phaseIncrement = 512.0f * freq / sample_rate_Hz;
}
/* Externally, phase comes in the range (0,2*M_PI) keeping with C math functions
* For convenience internally, the full circle is represented as (0.0, 512.0).
* This function allows multiple mixers to be phase coordinated (stop
* interrupts when setting).
*/
void iqmPhaseS(float32_t a) {
while (a < 0.0f) a += MF_TWOPI;
while (a > MF_TWOPI) a -= MF_TWOPI;
phaseS = 512.0f * a / MF_TWOPI;
doSimple = false;
return;
}
// phaseS_C_r is the number of radians that the cosine output leads the
// sine output. The default is M_PI_2 = pi/2 = 1.57079633 radians,
// corresponding to 90.00 degrees cosine leading sine.
// This is used to correct hardware phase unbalance
void iqmPhaseS_C(float32_t a) {
while (a < 0.0f) a += MF_TWOPI;
while (a > MF_TWOPI) a -= MF_TWOPI;
// Internally a full circle is 512.00 of phase
phaseS_C = 512.0f * a / MF_TWOPI;
doSimple = false;
return;
}
// Sets the gain g for the I channel.
// The Q channel is always 1.0. This is used to correct hardware
// amplitude unbalance.
void iqmAmplitude(float32_t g) {
amplitude_pk = g;
doSimple = false;
return;
}
// Channel 0 (left) is real for single input, or is I for
// complex input. With twoChannel===true channel 1 is Q.
void useTwoChannel(bool _2Ch) {
twoChannel = _2Ch;
}
// Speed up calculations by setting phaseS_C=90deg, amplitude=1
void useSimple(bool s) {
doSimple = s;
if(doSimple) {
phaseS_C = 128.0f;
amplitude_pk = 1.0f;
}
return;
}
void setGainOut(float32_t _gainO) { // Rev 2023
gainOut = _gainO;
}
void setSampleRate_Hz(float32_t fs_Hz) {
sample_rate_Hz = fs_Hz; // Added 30Jan23 RSL
// Check freq range
if (freq > sample_rate_Hz/2.0f) freq = sample_rate_Hz/2.f;
// update phase increment for new frequency
phaseIncrement = 512.0f * freq / sample_rate_Hz;
}
void showError(uint16_t e) { // Serial.print errors in update()
errorPrintIQM = e;
}
virtual void update(void);
private:
audio_block_f32_t *inputQueueArray_f32[2];
float32_t freq = 1000.0f;
float32_t phaseS = 0.0f;
float32_t phaseS_C = 128.00; // 512.00 is 360 degrees
float32_t amplitude_pk = 1.0f;
float32_t sample_rate_Hz = AUDIO_SAMPLE_RATE_EXACT;
float32_t phaseIncrement = 512.00f * freq /sample_rate_Hz;
float32_t gainOut = 1.0f;
uint16_t block_size = AUDIO_BLOCK_SAMPLES;
uint16_t errorPrintIQM = 0; // Normally off
bool doSimple = true;
bool twoChannel = false; // Activates 2 channels for I-Q input
};
#endif