doctorsab Writing on science, experiments, stories, and how-tos by doctorsab. 2026-10-25T00:00:00Z https://doctorsab.in/ Srikrishna Acharya The Kalman Filter: Guessing Well From Noisy Sensors 2026-10-25T00:00:00Z https://doctorsab.in/posts/the-kalman-filter-guessing-well-from-noisy-sensors/ The Kalman filter blends a model's prediction with noisy measurements to estimate what a system is really doing, and it has quietly steered everything from Apollo to today's drones. CORNET: Testing Robots and Networks Together 2026-10-23T00:00:00Z https://doctorsab.in/posts/cornet-testing-robots-and-networks-together/ CORNET runs network and robot simulators from one config, making cyber-physical systems research easier to run, reproduce and compare. The ₹36 Lakh Lesson: Winning 70%, Losing Everything 2026-10-23T00:00:00Z https://doctorsab.in/posts/the-36-lakh-lesson-winning-70-losing-everything/ I won seven trades out of ten for six years and still lost ₹36 lakh. Here's how, and how I'm climbing out. Setting up a PPP interface with a GPRS shield on a Raspberry Pi 2015-04-29T00:00:00Z https://doctorsab.in/posts/gprs-shield-raspberry-pi/ Two files, a chat script, and a stable device name, so a Telit GPRS shield can bring up ppp0. The Hope Project 2014-02-05T00:00:00Z https://doctorsab.in/posts/the-hope-project/ In 2014 Mr P. Suresh asked for a loan so Gnana Jyothi Public School could repair its building. The appeal was fully funded. My first interview 2010-09-29T13:02:00Z https://doctorsab.in/posts/my-first-interview/ An Army interview, an orange shirt, a seven-hour wait, and an answer I regretted on the way out. I want to live, Mommy 2010-09-29T12:59:00Z https://doctorsab.in/posts/i-want-to-live-mommy/ A letter in a child's voice, written after the child did not get to be born. Google Transliteration 2010-04-25T00:00:00Z https://doctorsab.in/posts/google-transliteration/ Type in English and read the word in Telugu, Hindi, Tamil, and other languages, from Google Labs and from the offline IME. Incredible white 2010-04-02T00:53:00Z https://doctorsab.in/posts/incredible-white/ A short list of names and phrases that begin with white, from a butterfly to a kind of noise. Brain facts 2010-04-02T00:51:00Z https://doctorsab.in/posts/brain-facts/ Weight, speed, oxygen, and a few other numbers for an ordinary human brain. Brain drain and brain gain 2010-04-02T00:50:00Z https://doctorsab.in/posts/brain-drain-and-brain-gain/ Skilled people leave one country and arrive in another. One side calls it a drain. The other calls it a gain. Technology — the best of 2009 2010-04-02T00:42:00Z https://doctorsab.in/posts/technology-best-of-2009/ Four machines that stood out in 2009: two netbooks, a pocket camcorder, Windows 7, and a MacBook Pro. Encounter 2010-03-19T00:00:00Z https://doctorsab.in/posts/encounter/ A paper presentation, a girl named Ashwini, and a conversation that ended when the events were cancelled. I will preserve these moments 2009-10-16T00:00:00Z https://doctorsab.in/posts/i-will-preserve-these-moments/ The evening I won my first paper presentation, and what the work had tasted like. How Mahatma became Mahatma 2009-10-01T00:00:00Z https://doctorsab.in/posts/how-mahatma-became-mahatma/ A short note on why Gandhi's name travelled farther than his own country. Attitudinal problems 2009-03-18T00:00:00Z https://doctorsab.in/posts/attitudinal-problems/ An attitude is a label we put on behaviour we dislike, and naming the behaviour works better than naming the attitude. It's all a game 2009-01-12T00:00:00Z https://doctorsab.in/posts/its-all-a-game/ A short argument about meat, money, trust, and why being cheated is treated as the worse offence. Let's get it started 2009-01-11T00:00:00Z https://doctorsab.in/posts/lets-get-it-started/ I waited too long to start the blog, then a presentation and a thin downline taught me what I had actually been missing.