Introduction to Signals

The Concept of Frequency

A complex sinusoid V rotating in time IQ-plane and generating two real sinusoids

Wireless signals between two devices travel through the use of radio waves. A radio wave is an electromagnetic wave propagated by an antenna. Radio waves have different frequencies, and one can pick up a specific signal by tuning a radio…
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Some Signal Classifications

Plot of a quadratic signal with time

Some signals have specific properties which makes computations simpler. For example, Even and Odd A signal is called even (or symmetric) if     Flipping an even signal around amplitude axis results in the same signal. Examples of even signals…
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Discrete Frequency

Discrete frequency axis obtained by sampling the continuous frequency axis

We have talked about the concept of frequency and sampling a continuous-time signal to generate a discrete-time signal. Remember that the reason we work with discrete-time signals is that finite computer memory can store only a fixed number of time…
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Transforming a Signal

A signal plot with its present, now and future

Transforming a discrete-time signal — whether in time or amplitude — is certainly possible, and often in interesting ways. In practice, scaling and time shifting are the two most important signal modifications encountered. Scaling changes the values of dependent variable…
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DFT Examples

Magnitude and phase of the DFT of a rectangular signal for L = 7, N= 16 and starting sample shifted by one

Having covered the Discrete Fourier Transform (DFT) and the concept of phase, we discuss a few examples of DFTs of some basic signals that will help not only understand the Fourier transform but will also be useful in comprehending concepts…
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