You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: noiseOverlay.m
    path of file: ./repos/Frequency-Hopping/src
    
    the code of the file until where you have to start completion: function [ signalNoisy ] = noiseOverlay(sys, Hd, signal, noise, snr)
% @intro, 为信号叠加噪声
% sys@param, 系统参数结构体
% Hd@param, 滤波器结构体
% signal@param, 待叠加噪声的信号
% noise@param, 带限噪声
% signalNoisy@retrval, 叠加噪声后的带限信号

NOISE_POWER = sys.NOISE_POWER;      % 噪声功率

    
function [ signalNoisy ] = noiseOverlay(sys, Hd, signal, noise, snr)
% @intro, 为信号叠加噪声
% sys@param, 系统参数结构体
% Hd@param, 滤波器结构体
% signal@param, 待叠加噪声的信号
% noise@param, 带限噪声
% signalNoisy@retrval, 叠加噪声后的带限信号

NOISE_POWER = sys.NOISE_POWER;      % 噪声功率

% 信号滤波并移除滤波器带来的延时
filtDelay = Hd.filtDelay;                       % 滤波器引入的延时
signal = [signal; zeros(filtDelay, 1)];
filtSignal = filter(Hd.Hd , signal);               % 信号滤波
filtSignal = filtSignal(filtDelay+1 : end