MATLAB SIGNAL PROCESSING TOOLBOX 6 Instrukcja Użytkownika Pobierz pdf (Strona 12)

2 Basic Signal Processing Concepts

2-4

Waveform Generation: Time Vectors and Sinusoids

Most toolbox functions require you to begin with a vector representing a time base.

Consider generating data with a 1000 Hz sample frequency, for example. An appropriate

time vector is

t = (0:0.001:1)';

where the MATLAB colon operator creates a 1001-element row vector that represents

time running from 0 to 1 s in steps of 1 ms. The transpose operator (') changes the row

vector into a column; the semicolon (;) tells MATLAB to compute, but not display the

result.

Given t, you can create a sample signal y consisting of two sinusoids, one at 50 Hz and

one at 120 Hz with twice the amplitude.

y = sin(2*pi*50*t) + 2*sin(2*pi*120*t);

The new variable y, formed from vector t, is also 1001 elements long. You can add

normally distributed white noise to the signal and plot the first 50 points using

rng default;

yn = y + 0.5*randn(size(t));

plot(t(1:50),yn(1:50))

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MATLAB SIGNAL PROCESSING TOOLBOX 6 Instrukcja Użytkownika Strona 12