产生一个按键按下对应的信号，加入一定的高斯白噪声，并解码检测出来。设计GUI界面模拟按键界面。(GUI MATLAB code for gui.fig
%　　　GUI, by itself, creates a new GUI or raises the existing
%　　　singleton*.
%
%　　　H = GUI returns the handle to a new GUI or the handle to
%　　　the existing singleton*.
%
%　　　GUI('CALLBACK',hObject,eventData,handles,...) calls the local
%　　　function named CALLBACK in EXP_2.M with the given input arguments.
%
%　　　GUI('Property','Value',...) creates a new GUI or raises the
%　　　existing singleton*.　Starting from the left, property value pairs are
%　　　applied to the GUI before gui_OpeningFcn gets called.　An
%　　　unrecognized property name or invalid value makes property application
%　　　stop.　All inputs are passed to gui_OpeningFcn via varargin.)