% Frequency domain depiction of the GPS signal and thermal noise
% power

%Written by Kai Borre, October 1, 2005

f0 = 1.023e6;
delta_f = linspace(-15e6, 15e6, 999); % difference with respect to f0
noise_floor = 2*randn(1,length(delta_f))+db(2*1e-6);

figure(1);
h1 = plot(delta_f.*pi/2, db( (sinc(pi*delta_f/(2*f0))).^2./f0),...
                                                      'linewidth', 1.5,'linestyle','-');
hold on
h2 = plot(delta_f.*pi/2, noise_floor,'linewidth',1.5,'linestyle','--');
hleg = legend('GPS C/A','Noise floor, 2 MHz BW');
set(gca,'XTick',[-5*1e6  -1e6 0 1e6  5*1e6])
set(gca,'XTickLabel',{'-5','-1','0','1','5'})
axis([-5*f0 5*f0 -190 -80]);  
set(gca,'FontSize',16)
hold off
ylabel('Power  [dBm]')
xlabel('Frequency  [MHz]')
box off
legend('boxoff')
%title('Center Frequency 1575.42 MHz')

print -deps2 fig4_1
%%%%%%%%%%%%%%%%%%%%%% end fig41.m  %%%%%%%%%%%%%%%