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138 lines
4.9 KiB
138 lines
4.9 KiB
/*
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* RadioIQMixer_F32
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* 8 April 2020 Bob Larkin
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* With much credit to:
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* Chip Audette (OpenAudio) Feb 2017
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* and of course, to PJRC for the Teensy and Teensy Audio Library
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*
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* A basic building block is a pair of mixers fed in parallel with the
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* LO going to the mixers at the same frequency, but differing in phase
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* by 90 degrees. This provides two outputs I and Q that are offset in
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* frequency but also 90 degrees apart in phase. The LO are included
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* in the block, but there are no post-mixing filters.
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*
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* The frequency is set by .frequency(float freq_Hz)
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* Particularly for use in transmitting, there is provision for varying
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* the phase between the sine and cosine oscillators. Technically this is no
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* longer sin and cos, but that is what real hardware needs.
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*
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* The output levels are 0.5 times the input level.
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*
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* Status: Tested in doSimple==1
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* Tested in FineFreqShift_OA.ino, T3.6 and T4.0
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*
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* Inputs: 0 is signal
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* Outputs: 0 is I 1 is Q
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*
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* Functions, available during operation:
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* void frequency(float32_t fr) Sets BFO frequency Hz
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* void iqmPhaseS(float32_t ps) Sets Phase of Sine in radians
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* void phaseS_C_r(float32_t pc) Sets relative phase of Cosine in radians, approximately pi/2
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* void amplitudeC(float32_t a) Sets relative amplitude of Sine, approximately 1.0
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* void useSimple(bool s) Faster if 1, but no phase/amplitude adjustment
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* void setSampleRate_Hz(float32_t fs_Hz) Allows dynamic sample rate change for this function
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*
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* Time: T3.6 For an update of a 128 sample block, doSimple=1, 46 microseconds
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* T4.0 For an update of a 128 sample block, doSimple=1, 20 microseconds
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*/
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#ifndef _radioIQMixer_f32_h
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#define _radioIQMixer_f32_h
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#include "AudioStream_F32.h"
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#include "arm_math.h"
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#include "mathDSP_F32.h"
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class RadioIQMixer_F32 : public AudioStream_F32 {
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//GUI: inputs:2, outputs:2 //this line used for automatic generation of GUI node
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//GUI: shortName: IQMixer
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public:
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// Option of AudioSettings_F32 change to block size or sample rate:
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RadioIQMixer_F32(void) : AudioStream_F32(1, inputQueueArray_f32) {
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// Defaults
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}
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RadioIQMixer_F32(const AudioSettings_F32 &settings) : AudioStream_F32(1, inputQueueArray_f32) {
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setSampleRate_Hz(settings.sample_rate_Hz);
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block_size = settings.audio_block_samples;
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}
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void frequency(float32_t fr) { // Frequency in Hz
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freq = fr;
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if (freq < 0.0f) freq = 0.0f;
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else if (freq > sample_rate_Hz/2.0f) freq = sample_rate_Hz/2.0f;
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phaseIncrement = 512.0f * freq / sample_rate_Hz;
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}
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/* Externally, phase comes in the range (0,2*M_PI) keeping with C math functions
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* Internally, the full circle is represented as (0.0, 512.0). This is
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* convenient for finding the entry to the sine table.
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*/
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void iqmPhaseS(float32_t a) {
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while (a < 0.0f) a += MF_TWOPI;
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while (a > MF_TWOPI) a -= MF_TWOPI;
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phaseS = 512.0f * a / MF_TWOPI;
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doSimple = false;
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return;
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}
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// phaseS_C_r is the number of radians that the cosine output leads the
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// sine output. The default is M_PI_2 = pi/2 = 1.57079633 radians,
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// corresponding to 90.00 degrees cosine leading sine.
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void iqmPhaseS_C(float32_t a) {
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while (a < 0.0f) a += MF_TWOPI;
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while (a > MF_TWOPI) a -= MF_TWOPI;
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// Internally a full circle is 512.00 of phase
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phaseS_C = 512.0f * a / MF_TWOPI;
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doSimple = false;
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return;
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}
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// The amplitude, a, is the peak, as in zero-to-peak. This produces outputs
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// ranging from -a to +a. Both outputs are the same amplitude.
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void iqmAmplitude(float32_t a) {
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amplitude_pk = a;
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doSimple = false;
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return;
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}
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// Speed up calculations by setting phaseS_C=90deg, amplitude=1
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void useSimple(bool s) {
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doSimple = s;
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if(doSimple) {
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phaseS_C = 128.0f;
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amplitude_pk = 1.0f;
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}
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return;
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}
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void setSampleRate_Hz(float32_t fs_Hz) {
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// Check freq range
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if (freq > sample_rate_Hz/2.0f) freq = sample_rate_Hz/2.f;
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// update phase increment for new frequency
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phaseIncrement = 512.0f * freq / fs_Hz;
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}
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void showError(uint16_t e) { // Serial.print errors in update()
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errorPrintIQM = e;
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}
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virtual void update(void);
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private:
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audio_block_f32_t *inputQueueArray_f32[1];
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float32_t freq = 1000.0f;
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float32_t phaseS = 0.0f;
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float32_t phaseS_C = 128.00; // 512.00 is 360 degrees
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float32_t amplitude_pk = 1.0f;
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float32_t sample_rate_Hz = AUDIO_SAMPLE_RATE_EXACT;
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float32_t phaseIncrement = 512.00f * freq /sample_rate_Hz;
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uint16_t block_size = AUDIO_BLOCK_SAMPLES;
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uint16_t errorPrintIQM = 0; // Normally off
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// if only freq() is used, the complexities of phase, phaseS_C,
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// and amplitude are not used, speeding up the sin and cos:
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bool doSimple = true;
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};
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#endif
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