import numpy as np
import matplotlib.pyplot as plt
from dtk.process import freq_spectrum

sample_rate = 1000
duration = 1.0
time = np.linspace(0.0, duration, num=int(duration*sample_rate) + 1)

low_freq = 2.0*np.sin(5.0*2.0*np.pi*time)  # 5 Hz * 2 pi rad / cycle
high_freq = np.sin(50.0*2.0*np.pi*time)  # 50 Hz * 2 pi rad / cycle

fig, ax = plt.subplots(layout='constrained')
ax.plot(time, low_freq + high_freq)
ax.set_xlim((0.0, 0.4))
ax.set_xlabel('Time [s]')
ax.set_ylabel('Amplitude')