python

Array pattern multiplication of phased array antennas

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Antenna models — reading order Maxwell’s equations Retarded potentials Near-field / far-field boundary Far-field retarded potentials Array pattern multiplication (this article) Dipole power gain patterns Introduction Take one element’s radiation vector \(\mathbf{F}\), place \(N\) identical copies at positions \(\mathbf{l}_i\) with weights \(a_i\), and the far-field total factors as \(\mathbf{F}\,A\). That is pattern multiplication: the step … Read more

Matplotlib histogram and estimated PDF in Python

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Key focus: Shown with examples: let’s estimate and plot the probability density function of a random variable using Python’s Matplotlib histogram function. This post contains interactive python code which you can execute in the browser itself. Generation of random variables with required probability distribution characteristic is of paramount importance in simulating a communication system. Let’s … Read more

Linear regression using python – demystified

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Key focus: Let’s demonstrate basics of univariate linear regression using Python SciPy functions. Train the model and use it for predictions. Linear regression model Regression is a framework for fitting models to data. At a fundamental level, a linear regression model assumes linear relationship between input variables ($latex x$) and the output variable ($latex y$). … Read more

Generating simulated dataset for regression problems

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Key focus: Generating simulated dataset for regression problems using sklearn make_regression function (Python 3) is discussed in this article. Problem statement Suppose, a survey is conducted among the employees of a company. In that survey, the salary and the years of experience of the employees are collected. The aim of this data collection is to … Read more

Plot audio file as time series using Scipy python

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Often the most basic step in signal processing of audio files, one would like to visualize an audio sample file as time-series data. Audio sounds can be thought of as an one-dimensional vector that stores numerical values corresponding to each sample. The time-series plot is a two dimensional plot of those sample values as a … Read more

Plot FFT using Python – FFT of sine wave & cosine wave

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FFT Lab path:Complex DFT, bins & fftshift → Magnitude & phase → Spectral leakage → Plot: Matlab / PythonTool: FFT bin frequency & resolution calculator Key focus: Learn how to plot FFT of sine wave and cosine wave using Python. Understand FFTshift. Plot one-sided, double-sided and normalized spectrum using FFT. Introduction Numerous texts are available … Read more

Fibonacci sequence in python – a short tutorial

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Key focus: Learn to generate Fibonacci sequence using Python. Python 3 is used in this tutorial. Fibonacci series is a sequence of numbers 0,1,1,2,3,5,8,13,… Let’s digress a bit from signal processing and brush up basic some concepts in python programming. Why python? Python is an incredibly versatile programming language that is used for everything from … Read more

Phase demodulation via Hilbert transform: Hands-on

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Analytic Signal Lab (same on every page in this path) 1. Hilbert / FFT → 2. Envelope & IF → 3. Phase demodulation (you are here) Tools: Hilbert / analytic signal demo Key focus: Demodulation of phase modulated signal by extracting instantaneous phase can be done using Hilbert transform. Hands-on demo in Python & Matlab. … Read more