About

Hello and welcome to Wireless Pi.

I am Qasim Chaudhari and here is some background on how this website started.

Background


One day at work, my friend Azam gave me Digital Communications – A Discrete-Time Approach written by Michael Rice. Reading a few pages of his book ignited a spark in my heart and made me wonder how could something be so beautiful and coherent. It was like poetry. The preface introduced me to fred harris and his book Multirate Signal Processing for Communication Systems. I read them multiple times and always found myself asking why these concepts seem complicated when they could be explained in a much easier manner. I realized that grandmasters usually focus more on exploring the exciting stuff than making it easier for others to comprehend. Since I had this coherent picture of the art of DSP applied to the science of wireless communications in my mind (or so I thought), I started writing about these topics myself.

During the past decade, I have worked in different universities and organizations, each time on a new project. This helped me in making new connections between seemingly disparate concepts and distinguishing the forest from the trees. It was surprising to discover that more knowledge actually takes less space in our minds. In words of Richard Feynman in The Pleasure of Finding Things Out:

“In the case of the chess game, the rules become more complicated as you go along, but in the physics, when you discover new things, it looks more simple. It appears on the whole to be more complicated, because we learn about a greater experience, that is, we learn about more particles and new things, and so the laws look complicated again. But if you realize that all the time what’s kind of wonderful is that, as we expand our experience into wilder and wilder regions of experience, every once in a while we have these integrations in which everything is pulled together in a unification, which turns out to be simpler than it looked before.”

Some biography


After obtaining a PhD in Electrical Engineering from Texas A&M University, I have mostly worked on DSP algorithms development for real world demonstrations of wireless systems such as a MIMO-OFDM testbed, a low-SNR receiver and phase of arrival based localization. As a dad of 3 kids, my time is spent on slowly emptying the queue of projects that entertain me the most.

I have spent some time of my life in a failed attempt to find the holy grail of DSP + wireless communications, i.e., extracting the range of a wireless device from a general communications signal itself (no separate communication and localization signals). This failure led me to the discovery that this goal can be accomplished for some particular modulation schemes. My current venture is to bring such experimental results from indoor multipath channels out in the real world for IEEE 802.15.4 (e.g., ZigBee) devices.

Stay in touch


On this website, I write about DSP, SDR and wireless communications in general. I am publishing several new articles on signal processing techniques and baseband algorithms for PHY design of digital wireless systems in the coming months. To receive them, you can subscribe via email here.

Or if you want to ask a specific question, you can contact me directly.

An Easy Visual Guide to SDR

Learn about SDR and wireless communications through (a) great visualizations, (b) simple mathematics and (c) answers to a lot of `why' questions. See the sample contents below.
Download the Free Contents
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There are 26 letters in English language and countless rules. The language of signal processing is simpler.

- It has only 1 letter: a sample at time 0. From there, we can build any discrete-time signal on which our 1s and 0s can be mapped.

- It has one major rule which is repeatedly employed for demapping the received signal to bits.


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