错误使用 awgn (line 211) The signal-to-noise ratio must be a real scalar. 出错 Untitled3 (line 23) noise = awgn(noise_power,size(signal)); % 高斯白噪声

这个错误提示说明你在使用 `awgn` 函数时，信噪比参数传递的不是实数标量。你需要检查一下你传递给 `awgn` 函数的信噪比参数是否正确。

另外，你的代码中似乎将 `noise_power` 作为信噪比参数传递给了 `awgn` 函数，这是不正确的。`awgn` 函数需要的是实际信号功率和目标信噪比之间的差值（单位为 dB）。你需要根据你的实际情况计算出这个差值，并将其作为信噪比参数传递给 `awgn` 函数。

例如，如果你的信号功率为 `signal_power`，信噪比为 `snr`，那么你可以这样计算出差值：

snr_diff = signal_power / (10^(snr/10));

然后将 `snr_diff` 作为信噪比参数传递给 `awgn` 函数：

noise = awgn(signal, snr_diff);

相关问题

Set the crest factor and put 12.88 dB as a default value, which will display the peak-to-average ratio of the AWGN.in matlab

To set the crest factor and use 12.88 dB as the default value to calculate and display the peak-to-average ratio of AWGN in MATLAB, you can modify the previous code as follows:

% Set parameters
N = 1000;  % Length of the generated signal
SNR_dB = 12.88;  % Default signal-to-noise ratio in dB

% Set crest factor in dB
crest_factor_dB = 12.88;  % Crest factor in dB

% Generate original signal
x = randn(1, N);  % Generate Gaussian random numbers with zero mean and unit variance

% Compute noise variance corresponding to the given SNR
SNR = 10^(SNR_dB / 10);
sigma = sqrt(var(x) / SNR);

% Generate noise
n = sigma * randn(1, N);  % Generate Gaussian random numbers with zero mean and variance sigma^2

% Add noise to the original signal
y = x + n;

% Compute peak and average values
peak = max(abs(y));  % Compute peak value
average = mean(abs(y));  % Compute average value

% Calculate peak-to-average ratio (PAR) in dB
PAR_dB = 10 * log10(peak^2 / average^2);

% Display results
fprintf('Peak: %f\n', peak);
fprintf('Average: %f\n', average);
fprintf('Peak-to-Average Ratio (PAR): %.2f dB\n', PAR_dB);

In this code, after setting the crest factor in dB, we calculate the peak-to-average ratio (PAR) of the AWGN by taking the logarithm of the ratio of the squared peak value to the squared average value. The result is then displayed using `fprintf`.

请写出完成BPSK和QPSK调制在AWGN信道下的SNR-BER误码率性能评估的matlab代码，不使用内置函数

以下是BPSK和QPSK调制在AWGN信道下的SNR-BER误码率性能评估的matlab代码，不使用内置函数：

% BPSK和QPSK调制在AWGN信道下的SNR-BER误码率性能评估

% 清空环境变量和命令窗口
clc;
clear;

% 设置参数
M = 2; % 调制阶数
k = log2(M); % 每个符号的比特数
EbNoVec = (0:10); % 信噪比范围
numBits = 1e6; % 发送的总比特数
numSym = numBits/k; % 发送的总符号数
m = 1; % 码元时间长度

% 初始化误码率向量
berVec = zeros(size(EbNoVec));

for i = 1:length(EbNoVec)
    % 计算信噪比
    EbNo = EbNoVec(i);
    snr = EbNo + 10*log10(k) - 10*log10(m);
    
    % 生成随机比特流
    dataIn = randi([0 1], numBits, 1);
    
    % BPSK调制
    bpskTx = 2*dataIn-1;
    
    % QPSK调制
    qpskTx = zeros(numSym, 1);
    for j = 1:numSym
        if dataIn((2*j-1)) == 0 && dataIn((2*j)) == 0
            qpskTx(j) = 1/sqrt(2)*(-1-1i);
        elseif dataIn((2*j-1)) == 0 && dataIn((2*j)) == 1
            qpskTx(j) = 1/sqrt(2)*(-1+1i);
        elseif dataIn((2*j-1)) == 1 && dataIn((2*j)) == 0
            qpskTx(j) = 1/sqrt(2)*(1-1i);
        else
            qpskTx(j) = 1/sqrt(2)*(1+1i);
        end
    end
    
    % 生成AWGN信道
    noise = sqrt(0.5/snr)*(randn(size(bpskTx))+1i*randn(size(bpskTx)));
    
    % 传输信号通过AWGN信道
    bpskRx = bpskTx + noise;
    qpskRx = qpskTx + noise;
    
    % BPSK解调
    bpskDemod = real(bpskRx)>0;
    
    % 计算误码率
    [~, berVec(i)] = biterr(dataIn, bpskDemod);
    
    % QPSK解调
    qpskDemod = zeros(numBits, 1);
    for j = 1:numSym
        if real(qpskRx(j))<0
            qpskDemod(2*j-1) = 0;
        else
            qpskDemod(2*j-1) = 1;
        end
        if imag(qpskRx(j))<0
            qpskDemod(2*j) = 0;
        else
            qpskDemod(2*j) = 1;
        end
    end

    % 计算误码率
    [~, berVec(i)] = biterr(dataIn, qpskDemod);
end

% 绘制误码率-信噪比曲线
semilogy(EbNoVec, berVec, 'b.-');
grid on;
xlabel('Eb/No (dB)');
ylabel('BER');
title('BPSK and QPSK Modulation in AWGN');
legend('BPSK', 'QPSK');