Sine Sweep(正弦掃頻信號)

本文主要參考：https://blog.csdn.net/okobul1/article/details/46415287

 

讀後記錄如下：

1. Sine sweep波的函數

sweep(t) = sin(2*PI*f0*(k^t-1)/log(k))

2. python的代碼

from math import * 
import array
import matplotlib.pyplot as plt
import wave

def sinesweep(f0, f1, sweeptime, samplingrate, peak): 
    k = exp(log(float(f1)/f0)/sweeptime)
    data_len = sweeptime * samplingrate
    data = array.array('i',[0]*data_len)
    dt = 1.0/samplingrate
    t = 0.0 
    p = 2*pi*f0/log(k)
    for i in range(data_len):
        data[data_len-i-1] = int(peak*sin( p*(pow(k,t)-1) ))
        t += dt 
    return data

def sindata(f0, time, samplingrate, peak): 
    data = [int(peak*sin(2*pi*f0*x/samplingrate)) for x in xrange(int(time*samplingrate))] 
    return array.array('h', data)

if 1:
    SAMPLING_RATE = 44100 
    SWEEP_TIME = 2
    F0 = 20 
    F1 = 20000 
    PEAK = 0x2000 
    data = sinesweep(F0, F1, SWEEP_TIME, SAMPLING_RATE, PEAK) 
    plt.title("sweep data")
    plt.plot(data)
    plt.show()
if 1 :
    f = wave.open("sweep.wav","wb")
    f.setnchannels(1) # mono wave 
    f.setsampwidth(2) # 16bit 
    f.setframerate(SAMPLING_RATE) #sampling rate 
    f.writeframes(data)
    f.close()

3.運行結果