Mercurial > forge
view main/comm/inst/prbs_generator.m @ 5670:503f32effbf7 octave-forge
Fix permission of prbs_*.m scripts
author | rlaboiss |
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date | Fri, 22 May 2009 12:48:17 +0000 |
parents | 5e329301ac7c |
children | 7e364201a793 |
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## ## (C) 2006 Muthiah Annamalai <muthuspost@gmail.com> ## ## Implement book keeping for a Pseudo-Random Binary Sequence ( PRBS ) ## also called as a Linear Feedback Shift Register. ## ## Given a polynomial create a PRBS structure for that polynomial. ## Now all we need is to just create this polynomial and make it work. ## polynomial must be a vector containing the powers of x and an optional ## value 1. eg: x^3 + x^2 + x + 1 must be written as [3 2 1 0] ## all the coefficients are either 1 or 0. It generates only a Binary \ ## sequence, and the generator polynomial need to be only a binary ## polynomial in GF(2). ## ## connections, contains a struct of vectors where each vector is the ## connection list mapping its vec(2:end) elements to the vec(1) output. ## ## Example: If you had a PRBS shift register like the diagram ## below with 4 registers we use representation by polynomial ## of [ 1 2 3 4], and feedback connections between [ 1 3 4 ]. ## The output PRBS sequence is taken from the position 4. ## ## +---+ +----+ +---+ +---+ ## | D |----| D |---| D |---| D | ## +---+ +----+ +---+ +---+ ## | | | ## \ / / ## [+]---------------+------+ ## 1 + 0.D + 1.D^2 + 1.D^3 ## ## The code to implement this PRBS with a start state of [1 0 1 1] ## will be: ## ## prbs=prbs_generator([1 3 4],{[1 3 4]},[1 0 1 1]); ## x = prbs_sequence(prbs) #gives 15 ## ## prbs_iterator( prbs, 15 ) #15 binary digits seen ## [ 1 1 0 1 0 1 1 1 1 0 0 0 1 0 0 ] ## ## See Also: This function is to be used along with functions ## prbs_iterator, and prbs_sequence. ## function prbs=prbs_generator(polynomial,connections,initstate) prbs.reglen=max(polynomial); prbs.polynomial=polynomial; prbs.sregs=initstate; prbs.connections=connections; prbs.conlen=length(connections); return end