45 lines
1.1 KiB
Python
45 lines
1.1 KiB
Python
import math
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import matplotlib.pyplot as plt
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import numpy as np
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def goertzel_sinusoid(freq, duration, sample_rate, amplitude):
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n = int(duration * sample_rate)
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omega = (2.0 * math.pi * freq) / sample_rate
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coeff = 2.0 * math.cos(omega)
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# Initialize state variables
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q1 = 1.0 # previous sample in sinusoid (1.0 for sample 1)
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q2 = 1.0 # previous previous sample (approximately 1.0 for sample 1)
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result = []
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for i in range(n):
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sample = coeff * q1 - q2
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q2 = q1
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q1 = sample
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result.append(sample * amplitude)
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return result
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def sinusoid(n, cycles=1):
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result = []
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for i in range(1, n+1):
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sample = math.cos(2.0 * cycles * math.pi * (i/n))
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result.append(sample)
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return result
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def main():
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cycles = 2
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signal = goertzel_sinusoid(cycles, 1, 1024, 1)
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reference = np.array(sinusoid(1024, cycles))
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error = reference - signal
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print("max error:", error.max())
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x = np.array(range(0, 1024))
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plt.plot(x, signal)
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plt.plot(x, reference)
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plt.plot(x, error)
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#plt.plot(x, error*1000/3)
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plt.show()
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if __name__ == "__main__":
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main()
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