用MATLAB写代码对2FSK和2ASK抗噪性能分析画出误码率曲线

以下是MATLAB程序示例：

% 2FSK and 2ASK BER performance analysis
clear all;
close all;
clc;

% Modulation parameters
M = 2; % Number of symbols
fs = 100e3; % Sampling frequency
fc = 10e3; % Carrier frequency
T = 1/fs; % Sampling period
Tsym = 1e-3; % Symbol period
Nsym = round(Tsym/T); % Samples per symbol
fc1 = fc + 500; % Frequency of symbol 1
fc2 = fc - 500; % Frequency of symbol 2
A = 1; % Amplitude of symbols

% Channel parameters
SNRdB = 0:2:20; % SNR values in dB
SNR = 10.^(SNRdB/10); % SNR values in linear scale
sigma = sqrt(1./(2*SNR)); % Standard deviation of noise

% Generate random binary data
Nbits = 1e6; % Number of bits
data = randi([0 1],Nbits,1);

% Generate 2FSK modulated signal
t = (0:Nsym*Nbits-1)*T; % Time vector
s = A*cos(2*pi*fc1*t + 2*pi*(cumsum(data)*fc2*Tsym))); % 2FSK modulated signal

% Generate 2ASK modulated signal
s_ask = A*(2*data-1).*cos(2*pi*fc*t); % 2ASK modulated signal

% Add Gaussian noise to the signals
r_fsk = bsxfun(@plus,s(:),sigma(:).*randn(Nsym*Nbits,length(SNR))); % 2FSK signal with added noise
r_ask = bsxfun(@plus,s_ask(:),sigma(:).*randn(Nsym*Nbits,length(SNR))); % 2ASK signal with added noise

% Demodulate the signals
data_fsk = zeros(Nbits,length(SNR)); % Demodulated data for 2FSK
data_ask = zeros(Nbits,length(SNR)); % Demodulated data for 2ASK
for ii=1:length(SNR)
    % 2FSK demodulation
    demod_fsk = abs(hilbert(r_fsk(:,ii)).*exp(-1j*2*pi*fc1*t)); % Envelope detection and phase synchronization
    data_fsk(:,ii) = demod_fsk(Nsym:Nsym:end) > A/2; % Decision based on threshold
    
    % 2ASK demodulation
    demod_ask = r_ask(:,ii).*cos(2*pi*fc*t); % Amplitude detection
    data_ask(:,ii) = demod_ask(Nsym:Nsym:end) > 0; % Decision based on threshold
end

% Compute BER for 2FSK and 2ASK
BER_fsk = sum(xor(data,data_fsk))/Nbits; % Bit error rate for 2FSK
BER_ask = sum(xor(data,data_ask))/Nbits; % Bit error rate for 2ASK

% Plot BER vs SNR curves
figure;
semilogy(SNRdB,BER_fsk,'-o','LineWidth',2);
hold on;
semilogy(SNRdB,BER_ask,'-*','LineWidth',2);
grid on;
xlabel('SNR (dB)');
ylabel('Bit Error Rate');
legend('2FSK','2ASK');
title('BER vs SNR for 2FSK and 2ASK');

该程序生成随机二进制数据，并使用2FSK和2ASK对其进行调制。为了模拟噪声通道，程序添加了高斯白噪声。接下来，程序对接收信号进行解调，并计算误码率（BER）。

最后，程序绘制了2FSK和2ASK的BER vs SNR曲线。