Spread Spectrum Archives - GaussianWaves

Maximum-length sequence (m-sequence) generator

Mathuranathan — Mon, 24 Sep 2018 08:16:28 +0000

Key focus: Model and simulate m-sequence generator using Galois linear feedback shift registers (LFSR) that implement linear recursion. Plot correlation properties. Maximum-length sequences (also called as m-sequences or pseudo random (PN) sequences) are constructed based on Galois field theory which is an extensive topic in itself. A detailed treatment on the subject of Galois field theory ... Read more

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Gold code generator using LFSRs

Mathuranathan — Tue, 09 Jun 2015 10:12:41 +0000

Focus of this article is to discuss the details of Gold code generator using preferred pair m-sequences, implemented using linear feedback shift registers (LFSR). Finally we plot and investigate correlation properties of the generated Gold codes. Introduction In a multi-user environment (like spread spectrum, CDMA ) large number of codes with good correlation properties, is ... Read more

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Walsh Hadamard Code – Matlab Simulation

Mathuranathan — Thu, 03 Mar 2011 02:47:00 +0000

The following is a function to generate a Walsh Hadamard Matrix of given codeword size. The codeword size has to be a power of 2. function [H]=generateHadamardMatrix(codeSize) %[H]=generateHadamardMatrix(codeSize); % Function to generate Walsh-Hadamard Matrix where "codeSize" is the code % length of walsh code. The first matrix gives us two codes; 00, 01. The second ... Read more

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Codes used in CDMA

Mathuranathan — Mon, 28 Feb 2011 05:36:00 +0000

IS-95 CDMA Standard uses three types of codes namely 1) Long code 2) Short code and 3) Walsh Hadamard codes. Long Code: Long codes run at 1.2288 Mb/s and are 42 bits longs (created using a 42 bits LFSR register). It takes approx 41.2 days to repeat a long code at this rate. It is ... Read more

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Spread Spectrum Communications – Introduction

Mathuranathan — Tue, 28 Sep 2010 07:41:00 +0000

Spread spectrum system, originally developed for military applications, is extremely resistant to unauthorized detection, jamming, interference and noise. It converts a narrowband signal to wideband signal by the means of spreading. Standards like WiFi and bluetooth use spread spectrum technology such as direct sequence spread spectrum and frequency hopping spread spectrum respectively. Spread spectrum techniques ... Read more

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