Miscellaneous Archives

March 7, 2022 Miscellaneous

DSP and the Humand Mind

It is relatively straightforward to establish the power and potential of human organs. The results are deterministic and not much different than animals. For example, my arm or leg can move only within a certain range and perform a limited number of known tasks. On the other hand, the possibilities with the mind are unlimited. For example, it can plan and execute a drilling mission to dig tunnels in the moons Titan and Europa, all the while sitting here on planet earth! We can say that the mind is the most mysterious organ not only in the human body but in the entire universe. There are some similarities between the functioning of the mind and Digital Signal Processing (DSP) techniques

December 29, 2020 Miscellaneous / Wireless/SDR

CDMA or OFDM

Reading about interference cancellation techniques today, I recalled an interesting article by Sridhar Vembu titled Two Philosophies in CDMA: A Stroll Down Memory Lane. Vembu is the founder and CEO of Zoho Corporation, a venture which has turned him into a billionaire. He spent time both in academia (at Princeton) and in industry (at Qualcomm) working with the likes of Sergio Verdu in one camp and Andrew Viterbi in the other. Here are some excerpts from his article which is not available online anymore at the time of this writing. I have now worked a little over 10 years in the industry, after getting my PhD. In my very first year of work at Qualcomm, I noticed how even when

February 16, 2021 Miscellaneous

How Errors Lead to New Discoveries

In the book "Where Good Ideas Come From", the author Steven Johnson mentions some stories on how errors lead to new scientific breakthroughs which I think would be interesting for radio/wireless enthusiasts. The first among them is what laid the foundation for electronics and radio broadcasting. Audion (Triode) Vacuum Tube In the summer of 1900 a twenty-seven-year-old aspiring inventor named Lee de Forest moved to Chicago, rented a one-room apartment on Washington Boulevard, and took a day job translating foreign articles on wireless technology for Western Electrician magazine. The translation work was informative: a major exposition on wireless technology that had just been held in Paris guaranteed a constant flow of interesting new research papers across the Atlantic. But de

Plots for positive integer powers of x in 3D

June 26, 2020 DSP / Miscellaneous

A Real-Imaginative Guide to Complex Numbers

June 18, 2020 On a cold morning in August 2015, I narrowly missed a train to my office in Melbourne city. With nothing else to do in the next 20 minutes, my mind wandered towards an intuitive view of complex numbers, something that has puzzled me since long. In particular, I wanted to seek answers to the following questions. (a) What is the role of the number $\sqrt{-1}$ in mathematics? What sets it apart from other impossible numbers, e.g., a number $k$ such that $|k|=-1$? (The origins of this question might lie in how I cut apple slices for my kids as compared to my wife, see the figure below. I guess that many other dads also take this path

Bandwidth, power and DSP correspond to the traditional trio of raw materials, energy and knowledge

October 21, 2020 DSP / Miscellaneous / Wireless/SDR

Why Building an SDR Requires DSP Expertise

In an introduction to signals, we discussed the idea that the any activities around us, starting from subatomic particles to massive societal networks, are generating signals all the time. Since mathematics is the language of the universe and digital signals are nothing but quantized number sequences, it is fair to say that the workings of the universe can be mapped to an infinitely large set of signals. With these number sequences in hand, an electronic computer can process the signals and either extract the information about the surrounding real world phenomena or even better influence its target environment. We saw a simple example of this shift in the comparison between a correlator and a matched filter. After the great advancement