用matlab画出高斯白噪声信道下，信噪比-10dB-5dB中以下单型FM0码 ( M = 0 ) 和复型FM0码 ( M=1, 2, 3)的误码率对比图

在MATLAB中，我们可以使用通信系统工具箱来模拟高斯白噪声信道下的FM0编码，并计算不同信噪比（SNR）下的误码率（BER）。以下是一个示例代码，展示了如何生成单型FM0码（M=0）和复型FM0码（M=1, 2, 3）在不同信噪比下的误码率对比图。

% 清空环境变量和命令窗口
clear;
clc;

% 设置信噪比范围 (-10dB 到 -5dB)
snr_range = -10:0.5:-5; % dB

% 初始化误码率数组
ber_unipolar = zeros(length(snr_range), 1);
ber_bipolar = zeros(length(snr_range), 1);
ber_quadbipolar = zeros(length(snr_range), 1);
ber_octalbipolar = zeros(length(snr_range), 1);

% 循环遍历每个信噪比值
for i = 1:length(snr_range)
    snr_linear = 10^(snr_range(i)/10); % 将dB转换为线性值
    
    % 生成随机比特流
    data = randi([0 1], 1, 1000); % 假设发送1000个比特
    
    % 对数据进行FM0编码
    encoded_data_unipolar = fm0mod(data, 0, 'Coding', 'Unipolar');
    encoded_data_bipolar = fm0mod(data, 1, 'Coding', 'Bipolar');
    encoded_data_quadbipolar = fm0mod(data, 2, 'Coding', 'QuadBipolar');
    encoded_data_octalbipolar = fm0mod(data, 3, 'Coding', 'OctalBipolar');
    
    % 添加高斯白噪声
    noisy_data_unipolar = awgn(encoded_data_unipolar, snr_linear, 'measured');
    noisy_data_bipolar = awgn(encoded_data_bipolar, snr_linear, 'measured');
    noisy_data_quadbipolar = awgn(encoded_data_quadbipolar, snr_linear, 'measured');
    noisy_data_octalbipolar = awgn(encoded_data_octalbipolar, snr_linear, 'measured');
    
    % 解码并计算误码率
    decoded_data_unipolar = fm0demod(noisy_data_unipolar, 0);
    decoded_data_bipolar = fm0demod(noisy_data_bipolar, 1);
    decoded_data_quadbipolar = fm0demod(noisy_data_quadbipolar, 2);
    decoded_data_octalbipolar = fm0demod(noisy_data_octalbipolar, 3);
    
    ber_unipolar(i) = biterr(data, decoded_data_unipolar) / length(data);
    ber_bipolar(i) = biterr(data, decoded_data_bipolar) / length(data);
    ber_quadbipolar(i) = biterr(data, decoded_data_quadbipolar) / length(data);
    ber_octalbipolar(i) = biterr(data, decoded_data_octalbipolar) / length(data);
end

% 绘制误码率对比图
figure;
plot(snr_range, ber_unipolar, '-o', snr_range, ber_bipolar, '-s', ...
     snr_range, ber_quadbipolar, '-d', snr_range, ber_octalbipolar, '-x');
legend('Unipolar FM0', 'Bipolar FM0', 'QuadBipolar FM0', 'OctalBipolar FM0');
title('FM0 Code BER vs SNR');
xlabel('SNR (dB)');
ylabel('Bit Error Rate');
grid on;