# weetabixharry

1. #### Working through Annex I.1 of the 802.11 PHY standard in MATLAB

Note: In earlier versions of the 802.11 standard, the (BCC) OFDM example was given in Annex G. However, an error existed (e.g. in IEEE Std 802.11-2007) in that the FCS was incorrect (see link or search online for "IEEE 802.11-09/0042r0").

The WiFi (802.11) standards documents are free to download from the IEEE webpages (see, for example, here). (Sadly, you are required to register first, which I would describe as irritating and pointless).

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Updated 31st October 2018 at 08:02 by weetabixharry

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2. #### Creating Partially Correlated Random Variables: Part II

by , 30th November 2014 at 19:37

In Part I of this blog, we saw that we can construct two partially correlated signals, x1(t) and x2(t), as:

$3 \;\;\;\;\;\;\;\;\;\;\;\;\;x_1(t)=\sqrt{P_1}s_1(t)\\ \;\;\;\;\;\;\;\;\;\;\;\;\;x_2(t)=\sqrt{P_2}\(\rho^*s_1(t)+\sqrt{(1-|\rho|^2)}s_2(t)\)$
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3. #### Creating Partially Correlated Random Variables: Part I

by , 30th November 2014 at 19:37

Note: This blog is split into two parts because edaboard limits the number of pictures and equations per blog. The second part can be found here: [link].

Introduction

It is often useful to be able to generate (real or complex-valued) signals with specific cross-correlations. In the simplest case, this means we want to produce two signals with a specified cross-correlation (and specified powers). Or, in the general case, it means we want to specify an ...

Updated 7th December 2014 at 20:01 by weetabixharry

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4. #### Estimating Frequency Over A Short Capture

by , 2nd November 2014 at 21:26

I was recently asked how to estimate the frequency of a noisy sine wave over a short capture. In this context, 'short' means the total capture duration relative to the period of the sine wave. So we may have, at most, a few periods of the sine wave (or, at worst, less than one period). Here is an example (download raw data: sine_data_40k.zip):

Clealy, there is less than ...

Updated 20th December 2014 at 12:32 by weetabixharry

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5. #### Polynomial Approximation (Line-Fitting): An Extremely Simple Method

by , 22nd March 2014 at 14:19

We often plot some data on a graph and wonder if there might be a simple mathematical function to describe what we see:

In many cases, a polynomial approximation would be particularly useful. That is, we want to describe the line in the form:

$3y(x)\;=\;a_0\;+\;a_1x\;+\;a_2x^2\;+\;\dots\;+\;a_Nx^N\;\;\;\;\;\;\;\;\;\;(1)$
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Updated 2nd November 2014 at 21:37 by weetabixharry

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