A Unit Impulse in Continuous-Time

Width of a sinc signal increases and approaches a constant, just like an eagle spreading its wings

This post treats the signals in continuous time which is different than the approach I adopted in my book. The book deals exclusively in discrete time. A unit impulse is defined as     The result is an impulse with…
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The Fundamental Problem of Synchronization

Phase jumps at every zero crossing from modulating data onto the carrier phase for a QPSK waveform

We have seen in the effect of phase rotation that the matched filter outputs do not map back perfectly onto the expected constellation, even in the absence of noise and no other distortion. Unless this rotation is small enough, it…
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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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