Representing Signals
Numeric Arrays
The central data construct in the MATLAB environment is
the numeric array, an ordered collection of real
or complex numeric data with two or more dimensions. The basic data
objects of signal processing (one-dimensional signals or sequences,
multichannel signals, and two-dimensional signals) are all naturally
suited to array representation.
Back to Top
Vector Representation
MATLAB represents ordinary one-dimensional sampled
data signals, or sequences, as vectors.
Vectors are 1-by-n or n-by-1
arrays, where n is the number of samples in the
sequence. One way to introduce a sequence is to enter it as a list
of elements at the command prompt. The statement
x = [4 3 7 -9 1];
creates a simple five-element real sequence in a row vector.
Transposition turns the sequence into a column vector
x = x';
resulting in
x =
4
3
7
-9
1
Column orientation is preferable for single channel signals
because it extends naturally to the multichannel case. For multichannel
data, each column of a matrix represents one channel. Each row of
such a matrix then corresponds to a sample point. A three-channel
signal that consists of x, 2x,
and x/π is
y = [x 2*x x/pi]
This results in
y =
4.0000 8.0000 1.2732
3.0000 6.0000 0.9549
7.0000 14.0000 2.2282
-9.0000 -18.0000 -2.8648
1.0000 2.0000 0.3183
If the sequence has complex-valued elements, the transpose operator
takes the conjugate of the sequence elements. To transform a complex-valued
row vector into a column vector without taking conjugates:
x=[1-i 3+i 2+3*i 4-2*i]; %1X4
x=x.'; %4X1
Back to Top
 | Basic Signal Processing Concepts | | Waveform Generation: Time Vectors and Sinusoids |  |
Includes the most popular MATLAB recorded presentations with Q&A sessions led by MATLAB experts.
Get the Interactive Kit
Store 
