**Sampling a signal**

- To sample a signal in MATLAB, generate a time vector at the appropiate
rate, and use this to generate the signal. Plot using the
`stem`function. For example:% Sample the sinusoid x = sin(2 pi f t), where f = 2 kHz. % Let x1 be the signal sampled at 10 kHz. % Let x2 be the signal sampled at 3 kHz. f = 2000; T = 1/f; tmin = 0; tmax = 5*T; % Plot 5 cycles dt1 = 1/10000; dt2 = 1/3000; t1 = tmin:dt1:tmax; t2 = tmin:dt2:tmax; x1 = sin(2*pi*f*t1); x2 = sin(2*pi*f*t2); subplot(211) stem(t1,x1); subplot(212) stem(t2,x2);

- It is useful to plot the continuous time signal on the same plot.
All signals in MATLAB are discrete-time, but they will look like
continuous-time signals if the sampling rate is much higher than the Nyquist
rate:
% Sample the sinusoid x = sin(2 pi f t), where f = 2 kHz, and plot the sampled % signals over the continuous-time signal. % Let x1 be the signal sampled at 10 kHz. % Let x2 be the signal sampled at 3 kHz. f = 2000; T = 1/f; tmin = 0; tmax = 5*T; dt = T/100; dt1 = 1/10000; dt2 = 1/3000; t = tmin:dt:tmax; t1 = tmin:dt1:tmax; t2 = tmin:dt2:tmax; x = sin(2*pi*f*t); x1 = sin(2*pi*f*t1); x2 = sin(2*pi*f*t2); subplot(211) plot(t,x,'r'); hold on stem(t1,x1); subplot(212) plot(t,x,'r'); hold on stem(t2,x2);