7.6.m

估算并画出高斯脉冲的前15阶导函数的-10dB带宽。函数以下列变量为输入：a的最小值alphamin

%
% FUNCTION 7.6 : "cp0702_Gaussian_derivatives_
%  10dB_bandwidth"
%
% Analysis of -10 dB of the first 15 derivatives of the
%
% 'smp' samples of the Gaussian pulse are considered in
% the time interval 'Tmax - Tmin'
%
% The function receives as input:
% 1) the minimum value of the shape factor 'alphamin'
% 2) the increase step 'alphastep'
% 3) the number of values to be investigated
     'N_alphavalues'
%
% The function computes the ESDs of
% the first 15 derivatives of the Gaussian pulse for the
% 'alpha' value received as input,and then evaluates and
% plots the -10 dB bandwidth for each derivative
%
% Programmed by Luca De Nardis

function cp0702_Gaussian_derivatives_10dB_bandwidth(...
    alphamin,alphastep,N_alphavaluse)

% -----------------------------------------------
% Step Zero - Input parameters and initialization
% -----------------------------------------------

smp=4096;               % number of samples
alpha=alphamin;         % Gaussian pulse form factor
Tmin=-4e-9;             % lower time limit
Tmax=4e-9;              % upper time limit
threshold=-10;          % threshold (in dB) used to compute
                        % the bandwidth
                        
t=linspace(Tmin,Tmax,smp);% initialization of the time axis

dt=(Tmax - Tmin) / smp;   % sampling period

for j=1:N_alphavalues
    
    factor(j)=alpha;
    
    for i=1:15
        
% -------------------------------------------
% Step One - Pulse waveform in the time domain
% -------------------------------------------
        derivative(i,:)=...
            cp0702_analytical_waveforms(t,i,alpha);
        derivative(i,:)=derivative(i,:)/...
            max(abs(derivative(i,:)));
        
% -------------------------------------------
% Step Two - Analysis in the frequency domain and
%            evaluation of -10 dB bandwidth
% -------------------------------------------

         [Ess,f_high,f_low,BW] = ...
             cp0702_bandwidth(derivative(i,:),dt,threshold);
        minus10dbBand(i,j)=BW;
        
    end
    %increase of alpha value for the next step
    alpha = alpha + alphastep;
end

% -----------------------------
% Step Three - Graphical output
% -----------------------------

F=figure(1);
plot(factor,minus10dbBand');
axis([2e-10 12e-10 1e9 6e9]);
AX=gca;
set(AX,'FontSize',12);
X=xlabel('\alpha [s]');
set(X,'FontSize',14);
Y=ylabel('-10 dB Bandwidth [Hz]');
set(Y,'FontSize',14);
grid on 
derivebehaviour = {'Increasing differentiation order'};

text(7e-10, 3e9, derivebehaviour,'BankgroundColor',...
    [1 1 1]);