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All entries for Thursday 21 September 2006

## September 21, 2006

### System Identification Toolbox

This week, I am supposed to master the art of System Identification using the SI Toolbox of Matlab. My Senioe Design project will apparently be based heavily on it.

Since I have been doing loads of Fourier Related stuff it is nice for me to remind myself what does it really mean to be looking into a signal from the Frequency Domain…

Frequency domain is a term used to describe the analysis of mathematical functions or signals with respect to frequency. Speaking non-technically, a time domain graph shows how a signal changes over time, whereas a frequency domain graph shows how much of the signal lies within each given frequency band over a range of frequencies. A frequency domain representation can also include information on the phase shift that must be applied to each sinusoid in order to be able to recombine the frequency components to recover the original time signal. The frequency domain relates to the Fourier transform or Fourier series by decomposing a function into an infinite or finite number of frequencies. This is based on the concept of fourier series which is that any waveform can be expressed as a sum of sinusoids (sometimes infinitely many.)

*Wiki Defination*