Time-variant system
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A time-variant system is a system whose output response depends on moment of observation as well as moment of input signal application.[1] In other words, a time delay or time advance of input not only shifts the output signal in time but also changes other parameters and behavior. Time variant systems respond differently to the same input at different times. The opposite is true for time invariant systems (TIV).
Overview
There are many well developed
The following things can be said about a time-variant system:
- It has explicit dependence on time.
- It does not have an impulse response in the normal sense. The system can be characterized by an impulse response except the impulse response must be known at each and every time instant[dubious ].
- It is not stationary[clarification needed]
Linear time-variant systems
Linear-time variant (LTV) systems are the ones whose parameters vary with time according to previously specified laws. Mathematically, there is a well defined dependence of the system over time and over the input parameters that change over time.
In order to solve time-variant systems, the algebraic methods consider initial conditions of the system i.e. whether the system is zero-input or non-zero input system.
Examples of time-variant systems
The following time varying systems cannot be modelled by assuming that they are time invariant:
- The Earth's thermodynamic response to incoming Solar irradiance varies with time due to changes in the Earth's albedo and the presence of greenhouse gases in the atmosphere.[2][3]
- decimation operation[dubious].
See also
References
- ISBN 978-0470851043.
- ISSN 1996-1073.
- .