View RSS Feed


Entries with no category

  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).


    Updated 31st October 2018 at 08:02 by weetabixharry

  2. Creating Partially Correlated Random Variables: Part II

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

  3. Creating Partially Correlated Random Variables: Part I

    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].


    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

  4. Estimating Frequency Over A Short Capture

    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:

    Clealy, there is less than ...

    Updated 20th December 2014 at 12:32 by weetabixharry

    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	short_sine_capture.png 
Views:	2141 
Size:	8.1 KB 
ID:	110929   Click image for larger version. 

Name:	pwelch_test.png 
Views:	700 
Size:	7.1 KB 
ID:	110931   Click image for larger version. 

Name:	short_pwelch.png 
Views:	828 
Size:	7.0 KB 
ID:	110937   Click image for larger version. 

Name:	short_sine_fit.png 
Views:	721 
Size:	10.2 KB 
ID:	110941  
  5. Polynomial Approximation (Line-Fitting): An Extremely Simple Method

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

    Click image for larger version. 

Name:	y=f(x).png 
Views:	1210 
Size:	14.0 KB 
ID:	103465

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


    Updated 2nd November 2014 at 21:37 by weetabixharry

Page 1 of 2 1 2 LastLast