matlab的QAM调制解调
时间: 2023-12-12 08:35:40 浏览: 28
以下是MATLAB中16QAM信号的调制和解调的示例代码:
1. 16QAM信号的调制
```matlab
% 设置参数
ps = 1e6; % 符号速率
fc = 2e6; % 载波频率
Fs = 8e6; % 采样频率
a = 0.8; % 滚降因子
N = 1024; % 采样点数
M = 16; % QAM调制阶数
% 生成随机数据
data = randi([0 M-1], 1, N);
% 将数据转换为16QAM符号
qamData = qammod(data, M);
% 生成基带信号
t = 0:1/Fs:(N/ps-1/Fs);
baseband = real(qamData).*cos(2*pi*fc*t) - imag(qamData).*sin(2*pi*fc*t);
% 过滤
h = rcosdesign(a, 6, Fs/ps);
txSignal = upfirdn(baseband, h, ps, Fs);
% 绘制时域波形
figure;
plot(t(1:100), txSignal(1:100));
xlabel('Time (s)');
ylabel('Amplitude');
title('16QAM Modulated Signal (Time Domain)');
% 绘制频谱
f = linspace(-Fs/2, Fs/2, length(txSignal));
spectrum = fftshift(abs(fft(txSignal)));
figure;
plot(f, spectrum);
xlabel('Frequency (Hz)');
ylabel('Magnitude');
title('16QAM Modulated Signal (Frequency Domain)');
```
2. 16QAM信号的解调
```matlab
% 设置参数
ps = 1e6; % 符号速率
fc = 2e6; % 载波频率
Fs = 8e6; % 采样频率
a = 0.8; % 滚降因子
N = 1024; % 采样点数
M = 16; % QAM调制阶数
% 生成随机数据
data = randi([0 M-1], 1, N);
% 将数据转换为16QAM符号
qamData = qammod(data, M);
% 生成基带信号
t = 0:1/Fs:(N/ps-1/Fs);
baseband = real(qamData).*cos(2*pi*fc*t) - imag(qamData).*sin(2*pi*fc*t);
% 过滤
h = rcosdesign(a, 6, Fs/ps);
txSignal = upfirdn(baseband, h, ps, Fs);
% 添加高斯白噪声
snr = 10; % 信噪比
rxSignal = awgn(txSignal, snr, 'measured');
% 解调
t = 0:1/Fs:(N/ps-1/Fs);
carrier = cos(2*pi*fc*t) - 1i*sin(2*pi*fc*t);
demodSignal = rxSignal .* carrier;
h = rcosdesign(a, 6, Fs/ps);
demodSignal = upfirdn(demodSignal, h, 1, ps);
% 将解调后的信号转换为数字信号
rxData = qamdemod(demodSignal, M);
% 计算误码率
[numErrors, ber] = biterr(data, rxData);
% 输出结果
fprintf('SNR = %d dB\n', snr);
fprintf('Bit Error Rate = %5.2e\n', ber);
% 绘制时域波形
figure;plot(t(1:100), demodSignal(1:100));
xlabel('Time (s)');
ylabel('Amplitude');
title('16QAM Demodulated Signal (Time Domain)');
% 绘制频谱
f = linspace(-Fs/2, Fs/2, length(demodSignal));
spectrum = fftshift(abs(fft(demodSignal)));
figure;
plot(f, spectrum);
xlabel('Frequency (Hz)');
ylabel('Magnitude');
title('16QAM Demodulated Signal (Frequency Domain)');
```