问周期傅里叶变换信号的频域

EN

import scipy as sp
import math
import numpy as np
from scipy import signal
from scipy import fft
import matplotlib.pyplot as plt


paynowString = "00020101021126380009SG.PAYNOW010100211+658128992803010520400005303702545800.005802SG59006009Singapore620401006304"

characters = []

def split(word):
    return [char for char in word]

characters = split(paynowString)
print(characters)

ascii_characters = [ord(char) for char in characters]
print(ascii_characters)

positive_x_domain = np.zeros(9*len(ascii_characters))

rhs = []
xr = list(positive_x_domain)
for i in range(len(ascii_characters)):
    rhs = rhs + xr[i*9:(i*9+9)]+[ascii_characters[i]]
positive_x_domain = rhs + xr[(i+9)*9:]
positive_x_domain = np.asarray(positive_x_domain)
print(positive_x_domain)

negative_x_domain = np.flip(positive_x_domain)
print(negative_x_domain)

origin = np.array([0])

x_domain = np.concatenate((negative_x_domain, origin), axis = None)
x_domain = np.concatenate((x_domain, positive_x_domain), axis = None)
print(x_domain)


plt.plot(np.arange((-(len(x_domain)-1)/2), ((len(x_domain)-1)/2)+1), x_domain)
plt.margins(0.1, 0.1)
plt.xlabel('Time [samples]')
plt.ylabel('Amplitude')
plt.grid(True)
plt.show()

sound_wave = fft.ifft(x_domain)

plt.plot((-(len(x_domain)-1)/2), (((len(x_domain)-1)/2)+1), sound_wave)
plt.margins(0.1, 0.1)
plt.xlabel('Time [samples]')
plt.ylabel('Amplitude')
plt.axis([-0.1, 2500, -0.1, 1])
plt.grid(True)
plt.show()
#end of sending the sound wave