用MATLAB实现完整2ASK调制,包含解调,滤波,抽样判决,误码率随信噪比变化
时间: 2024-03-15 14:45:26 浏览: 68
好的,下面是完整的2ASK调制和解调的MATLAB实现:
1. 定义调制参数
```matlab
f = 100; % 信号频率
fs = 1000; % 采样频率
T = 1/fs; % 采样时间间隔
A = 1; % 振幅
```
2. 生成数字序列
```matlab
bits = randi([0,1],1,1000); % 随机生成1000个二进制数字
```
3. 将数字序列转换为二进制振幅移位信号
```matlab
binary_signal = A*(2*bits-1);
```
4. 生成调制信号
```matlab
t = 0:T:(length(bits)*T-T); % 时间序列
carrier_signal = A*sin(2*pi*f*t); % 载波信号
modulated_signal = carrier_signal.*binary_signal; % 调制信号
```
5. 加入高斯白噪声
```matlab
SNR = 10; % 信噪比
noise = randn(1,length(modulated_signal)); % 生成高斯白噪声
noise = noise./sqrt(sum(noise.^2)/length(noise)); % 调整噪声的功率为1
noise = noise.*sqrt(sum(modulated_signal.^2)/(10^(SNR/10)*length(modulated_signal))); % 调整噪声的功率,使其符合指定的信噪比
noisy_signal = modulated_signal + noise; % 加入噪声后的信号
```
6. 解调
```matlab
demodulated_signal = noisy_signal.*carrier_signal; % 解调信号
[b,a] = butter(10,2*f/fs); % 10阶低通滤波器
filtered_signal = filter(b,a,demodulated_signal); % 滤波后的信号
```
7. 抽样判决
```matlab
sampled_signal = filtered_signal(1:10:end); % 以10倍采样率进行抽样
decisions = sampled_signal>0; % 判决
```
8. 统计误码率
```matlab
error_bits = sum(xor(bits,decisions)); % 错误比特数
BER = error_bits/length(bits); % 误码率
```
9. 绘制误码率随信噪比变化曲线
```matlab
SNR_range = 0:2:20; % 信噪比范围
BERs = zeros(1,length(SNR_range)); % 误码率数组
for i = 1:length(SNR_range)
SNR = SNR_range(i);
noise = randn(1,length(modulated_signal));
noise = noise./sqrt(sum(noise.^2)/length(noise));
noise = noise.*sqrt(sum(modulated_signal.^2)/(10^(SNR/10)*length(modulated_signal)));
noisy_signal = modulated_signal + noise;
demodulated_signal = noisy_signal.*carrier_signal;
filtered_signal = filter(b,a,demodulated_signal);
sampled_signal = filtered_signal(1:10:end);
decisions = sampled_signal>0;
error_bits = sum(xor(bits,decisions));
BERs(i) = error_bits/length(bits);
end
plot(SNR_range,BERs);
xlabel('信噪比(dB)');
ylabel('误码率');
title('2ASK调制误码率随信噪比变化曲线');
```
通过以上代码,就可以实现完整的2ASK调制、解调、滤波、抽样判决和误码率随信噪比变化曲线的MATLAB实现了。