User`s guide

Signal Concepts
3-3
Signal Concepts
Simulink models can process both discrete-time and continuous-time signals,
although models that are built with the DSP Blockset are often intended to
process only discrete-time signals. The next few sections cover the following
topics:
•“Discrete-Time Signals” – A brief introduction to some of the common
terminology used for discrete-time signals, and a discussion of how
discrete-time signals are represented within Simulink
•“Continuous-Time Signals” – An explanation of how continuous-time signals
are treated by various blocks in the DSP Blockset
•“Multichannel Signals” – A description of how multichannel signals are
represented in Simulink
•“Benefits of Frame-Based Processing” – An explanation of how frame-based
processing achieves higher throughput rates
Discrete-Time Signals
A discrete-time signal is a sequence of values that correspond to particular
instants in time. The time instants at which the signal is defined are the
signal’s sample times, and the associated signal values are the signal’s samples.
Traditionally, a discrete-time signal is considered to be undefined at points in
time between the sample times. For a periodically sampled signal, the equal
interval between any pair of consecutive sample times is the signal’s sample
period, T
s
. The sample rate, F
s
, is the reciprocal of the sample period, or 1/T
s
.
The sample rate is the number of samples in the signal per second.
For example, the 7.5-second triangle wave segment below has a sample period
of 0.5 seconds, and sample times of 0.0, 0.5, 1.0, 1.5, ...,7.5. The sample rate of
the sequence is therefore 1/0.5, or 2 Hz.
time (s)
T
s
12345670