gmsk解调 matlab
时间: 2023-12-06 17:37:57 浏览: 34
以下是使用Matlab实现GMSK解调的代码示例:
```matlab
% 设置参数
fc = 1000; % 载波频率
fs = 8000; % 采样率
BT = 0.3; % 带限时间常数
Tb = 1/fs; % 采样时间间隔
Ts = 1/(2*fc); % 调制符号时间间隔
N = 1000; % 采样点数
% 生成GMSK调制信号
data = [1 0 1 1 0 0 1 0]; % 调制数据
phi = pi/2; % 初始相位
s = zeros(1, N); % 调制信号
for n = 1:length(data)
if data(n) == 1
phi = phi + pi*BT/Ts;
else
phi = phi - pi*BT/Ts;
end
s((n-1)*Ts/Tb+1:n*Ts/Tb) = sin(phi+(0:Ts/Tb-1)*pi/Ts);
end
% 加入高斯白噪声
Eb = sum(abs(s).^2)*Tb/length(s); % 平均比特能量
SNR = 10; % 信噪比
sigma = sqrt(Eb/(2*10^(SNR/10))); % 噪声标准差
r = s + sigma*randn(1, N); % 接收信号
% GMSK解调
phi_hat = zeros(1, N); % 估计的相位
for n = 2:N
phi_hat(n) = phi_hat(n-1) + 2*pi*BT/Ts*(r(n-1)*cos(phi_hat(n-1))-imag(hilbert(r(n-1))*sin(phi_hat(n-1))));
end
data_hat = zeros(1, length(data)); % 解调数据
for n = 1:length(data)
if phi_hat(n*Ts/Tb) > phi_hat((n-1)*Ts/Tb)
data_hat(n) = 1;
else
data_hat(n) = 0;
end
end
% 绘制图形
figure;
subplot(3, 1, 1);
plot(s);
title('GMSK调制信号');
subplot(3, 1, 2);
plot(r);
title('接收信号');
subplot(3, 1, 3);
plot(data_hat);
title('解调数据');
```