42 lines
1.4 KiB
C++
42 lines
1.4 KiB
C++
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#include <stdio.h>
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#include <math.h>
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// http://www.labbookpages.co.uk/audio/beamforming/delaySum.html
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// Number of freq points to calculate
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#define FREQ_RESOLUTION 500
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// Number of angle points to calculate
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#define ANGLE_RESOLUTION 500
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int main(void) {
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int numElements = 4; // Number of array elements
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double spacing = 0.2; // Element separation in metre
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double speedSound = 343.0; // m/s
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// Iterate through arrival angle points
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for (int32_t fff=0; fff<FREQ_RESOLUTION; ++fff) {
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double freq = 10000.0 * double(fff) / double(FREQ_RESOLUTION-1);
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for (int32_t aaa=0; aaa<ANGLE_RESOLUTION; ++aaa) {
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// Calculate the planewave arrival angle
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double angle = -90.0 + 180.0 * double(aaa) / double(ANGLE_RESOLUTION-1);
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double angleRad = M_PI * double(angle) / 180.0;
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double realSum = 0;
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double imagSum = 0;
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// Iterate through array elements
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for (iii=0; iii<numElements; ++iii) {
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// Calculate element position and wavefront delay
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double position = double(iii) * spacing;
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double delay = position * sin(angleRad) / speedSound;
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// Add Wave
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realSum += cos(2.0 * M_PI * freq * delay);
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imagSum += sin(2.0 * M_PI * freq * delay);
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}
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double output = sqrt(realSum * realSum + imagSum * imagSum) / numElements;
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double logOutput = 20.0 * log10(output);
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if (logOutput < -50.0) {
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logOutput = -50.0;
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}
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printf("%f %f %f\n", angle, freq, logOutput);
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}
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printf("\n");
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}
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return 0;
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}
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