Quadrature Amplitude Modulation (QAM)

A general QAM detector with respective waveforms at each block

We discussed earlier that Pulse Amplitude Modulation (PAM) transmits information through amplitude scaling of the pulse according to the symbol value. To understand QAM, we have to differentiate between baseband and passband signals. A baseband signal has a spectral magnitude…
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Finite Impulse Response (FIR) Filters

Time and frequency response of a lowpass FIR filter designed with Parks-McClellan algorithm for N=33

We learned in the concept of frequency that most signals of practical interest can be considered as a sum of complex sinusoids oscillating at different frequencies. The amplitudes and phases of these sinusoids shape the frequency contents of that signal…
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What is a System?

A system with input and output

In wireless communications and other applications of digital signal processing, we often want to modify a generated or acquired signal. A device or algorithm that performs some prescribed operations on an input signal to generate an output signal is called…
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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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