チョッパ

import numpy as np
import matplotlib.pyplot as plt
from scipy.signal import butter, filtfilt

# Time parameters
t = np.linspace(0, 1, 1000)  # 1 second with 1000 points

# Frequency parameters
sine_freq = 5  # Frequency of the sine wave (Hz)
triangle_freq = 10  # Frequency of the triangular wave (Hz)

# Generate a modulated sine wave (input signal)
modulated_sine_wave = np.sin(2 * np.pi * sine_freq * t)

# Generate a carrier triangular wave
carrier_triangle_wave = 2 * np.abs(2 * (t % (1 / triangle_freq)) * triangle_freq - 1) - 1

# Comparator output
comparator_output = modulated_sine_wave > carrier_triangle_wave

# LR circuit parameters
R = 10  # ohms
L = 0.01  # henry
dt = t[1] - t[0]

# Initialize voltage across the resistor
v_R = np.zeros_like(t)

# Calculate voltage across the resistor
for i in range(1, len(t)):
    di = (comparator_output[i] - v_R[i-1]/R) * dt / L
    v_R[i] = v_R[i-1] + di

# Apply a low-pass filter to the voltage across the resistor
def low_pass_filter(data, cutoff_freq, fs, order=5):
    nyquist = 0.5 * fs
    normal_cutoff = cutoff_freq / nyquist
    b, a = butter(order, normal_cutoff, btype='low', analog=False)
    y = filtfilt(b, a, data)
    return y

# Low-pass filter parameters
cutoff_freq = 1.0  # cutoff frequency of the low-pass filter (Hz)
fs = 1 / dt  # sampling frequency

# Apply the low-pass filter to the v_R signal
v_R_filtered = low_pass_filter(v_R, cutoff_freq, fs)

# Plotting
plt.figure(figsize=(12, 12))

plt.subplot(5, 1, 1)
plt.plot(t, modulated_sine_wave, label='Modulated Sine Wave')
plt.title('Modulated Sine Wave')
plt.xlabel('Time [s]')
plt.ylabel('Amplitude')
plt.grid(True)
plt.legend()

plt.subplot(5, 1, 2)
plt.plot(t, carrier_triangle_wave, label='Carrier Triangular Wave', color='orange')
plt.title('Carrier Triangular Wave')
plt.xlabel('Time [s]')
plt.ylabel('Amplitude')
plt.grid(True)
plt.legend()

plt.subplot(5, 1, 3)
plt.plot(t, comparator_output, label='Comparator Output', color='green')
plt.title('Comparator Output')
plt.xlabel('Time [s]')
plt.ylabel('Output')
plt.grid(True)
plt.legend()

plt.subplot(5, 1, 4)
plt.plot(t, v_R, label='Voltage across Resistor (v_R)', color='red')
plt.title('Voltage across Resistor (LR Circuit Output)')
plt.xlabel('Time [s]')
plt.ylabel('Voltage [V]')
plt.grid(True)
plt.legend()

plt.subplot(5, 1, 5)
plt.plot(t, v_R_filtered, label='Filtered Voltage across Resistor (v_R)', color='blue')
plt.title('Filtered Voltage across Resistor (Low-pass Filtered)')
plt.xlabel('Time [s]')
plt.ylabel('Voltage [V]')
plt.grid(True)
plt.legend()

plt.tight_layout()
plt.show()

import numpy as np
import matplotlib.pyplot as plt

# 定数の定義
fs = 1000  # サンプリング周波数
t = np.arange(0, 1, 1/fs)  # 時間ベクトル
f_input = 50  # 入力信号の周波数
f_lo = 200  # ローカルオシレータ信号の周波数

# 入力信号とローカルオシレータ信号の生成
input_signal = np.sin(2 * np.pi * f_input * t)
lo_signal = np.sign(np.sin(2 * np.pi * f_lo * t))  # スイッチング信号
lo_signal_dbm = np.sin(2 * np.pi * f_lo * t)

# スイッチングミキサ回路の出力の計算
mixer_output_switching = input_signal * lo_signal

# ダブルバランスドミキサ回路の出力の計算
mixer_output1 = input_signal * lo_signal_dbm
mixer_output2 = input_signal * (-lo_signal_dbm)
dbm_output = mixer_output1 - mixer_output2

# 結果のプロット
plt.figure(figsize=(12, 12))

plt.subplot(4, 1, 1)
plt.plot(t, input_signal, label='Input Signal')
plt.plot(t, lo_signal, label='Switching LO Signal', linestyle='--')
plt.plot(t, lo_signal_dbm, label='DBM LO Signal', linestyle='--')
plt.title('Input and LO Signals')
plt.xlabel('Time [s]')
plt.ylabel('Amplitude')
plt.legend()
plt.grid(True)

plt.subplot(4, 1, 2)
plt.plot(t, mixer_output_switching, label='Switching Mixer Output')
plt.title('Switching Mixer Output')
plt.xlabel('Time [s]')
plt.ylabel('Amplitude')
plt.legend()
plt.grid(True)

plt.subplot(4, 1, 3)
plt.plot(t, mixer_output1, label='DBM Mixer Output 1')
plt.plot(t, mixer_output2, label='DBM Mixer Output 2', linestyle='--')
plt.title('Double Balanced Mixer Intermediate Outputs')
plt.xlabel('Time [s]')
plt.ylabel('Amplitude')
plt.legend()
plt.grid(True)

plt.subplot(4, 1, 4)
plt.plot(t, dbm_output, label='DBM Output')
plt.title('Double Balanced Mixer Output')
plt.xlabel('Time [s]')
plt.ylabel('Amplitude')
plt.legend()
plt.grid(True)

plt.tight_layout()
plt.show()