www.pudn.com > MATLAB.rar > VCO_plot_dbc_per_hz.m, change:2010-01-07,size:779b


% Plot simulation results with log x axis.  
% Plot only + freq terms. 
% Per common practice, do not show carrier term. 
% Plot 1/f for reference, plus measured, plus specification  
% Copywrite 2004-2010 The MathWorks, Inc. 
index_start = 3;              % move out from carrier at DC and fft window effects 
Frame_Length = length(Normalized_Spectrum); 
Fvec_meas = Spectrum_dF*((index_start-1):Frame_Length/2); 
 
h2  =  findobj('Tag','plot_VCO'); 
if isempty(h2)  
   h2 =  figure('Tag','plot_VCO') 
else 
   figure(h2) 
end 
 
semilogx(Fvec_meas,10*log10(Normalized_Spectrum(index_start:(Frame_Length/2+1))),.... 
         Fvec,Lvec,'o'); 
xlabel('Hz from Carrier'); ylabel('dBc/Hz'); grid on; 
legend('Measured', 'specification'); 
axis([Fvec(1),Fvec_meas(end),-130,-30])