Time variant

arhzzz's picture


Joined: Apr 19, 2020

Replies: 0
Time variant
April 19, 2020 - 10:26pm

Hey guys im having a problem with this signal 

y(t) = Re{sin(t)x(t)}+ Im{jcos(t)x∗(t)} 


I need to check it if it is Time-invariant or time Time-variant is and im not sure how to do it. Maybe someone could help



jaksonlee's picture


Joined: Nov 07, 2019

Replies: 122
A time-variant system is a
April 20, 2020 - 5:31pm

time-variant system is a system whose output response depends on moment of observation as well as moment of input signal application. Time variant systems respond differently to the same input at different times. The opposite is true for time invariant systems.

There are many well developed techniques for dealing with the response of linear time invariant systems, such as Laplace and Fourier transforms. However, these techniques are not strictly valid for time-varying systems. A system undergoing slow time variation in comparison to its time constants can usually be considered to be time invariant: they are close to time invariant on a small scale. An example of this is the aging and wear of electronic components, which happens on a scale of years, and thus does not result in any behaviour qualitatively different from that observed in a time invariant system: day-to-day, they are effectively time invariant, though year to year, the parameters may change. Other linear time variant systems may behave more like nonlinear systems, if the system changes quickly – significantly differing between measurements.