# systemreboot – blog

## The Quadrifilar Helix and APT Yet Again!

Jul 6, 2014

Manjunath and I have been meaning to do something these hols - you know, just something to feel a sense of satisfaction before diving into regular coursework and stuff next semester. So, we finally decided to attempt a quadrifilar helix for APT reception, and here we are!

Tags: radio, satellite, rtlsdr, sdr, weather, antenna, project

## Walk to Sankey Tank

Jun 1, 2014

Just a pleasant Sunday morning's walk to Sankey tank with Tarun and Vaibhav…

Tags: walk

## IISc Mess Subsidy Protests

Apr 11, 2014

On Thursday, April 10, the students of IISc protested the administration's proposal to cancel the mess subsidy. I myself participated and was witness to the proceedings. Here is a short account of the events of the day and a comparison of various newspaper reports on the incident.

Tags: iisc, musing

## APT Again!

Jul 31, 2013

It is quite possible for someone to ask why, in the age of the Internet and the Television, and realtime weather reports, we need APT images. But, you will never know the joy of building your own equipment, and receiving your very own satellite images, until you have actually done it!

Tags: radio, satellite, rtlsdr, sdr, weather

## Like Frogs in a Well

May 23, 2013

Simple visualizations (such as the one shown in the figure) of this curvature, typically appeal to a 2D fabric of space curved into a third dimension by the presence of a mass such as the earth. This curvature creates a three dimensional "well" into which other masses fall, thus resulting in what we perceive as gravity.

Tags: musing, physics

## Over the Arabian Sea

Feb 26, 2013

…here at last, we have these spectacular images - images that rained down from the sky! It's true that they are still imperfect, and rather noisy (a situation that I intend to fix soon). But, anyway, here they be recorded, before the miracle of the moment passes away…

## RC Phase Shift Oscillator - Oscillation Criteria

Jan 20, 2013

Maxima is a computer algebra system. That's kinda like a calculator that can do algebra instead of just numerical calculations! I let Maxima cut through all the algebra of the RC phase shift network. Lo and behold, here we have the results, achieved almost painlessly!

Tags: electronics, maxima

## CyanogenMod 9 on my HTC Explorer!

Jan 8, 2013

I often hear all this talk about how the Explorer is a "low end budget device", about how 600 MHz is just too slow, and so on. But frankly, I can only classify all this as sales talk, or perhaps uninformed talk. Ice Cream Sandwich is not in any way slow on the Explorer, all hardware works fine, and I would certainly recommend anyone with an Explorer flashing to CyanogenMod 9.

Tags: android, cyanogenmod

## Frogs, Humans and the Radio

Oct 1, 2012

…in effect, SSB radio is like shouting above the din of the noise existing in the band. The noise always exists in the band, and in order to be heard, one must shout above the noise.

## Halo around Sun in Coimbatore - August 3, 2012

Aug 12, 2012

Coimbatore witnessed a spectacular halo on August 3, 2012… Just wanted to put up a photograph of the halo by my friend Udhaya Kumar…

Tags: weather

## Line Codes - Matlab / GNU Octave Code

Jul 19, 2012

I came up with the following approach to do line coding without for loops. My approach involves a bit of system theory, modulo 2 arithmetic, and sometimes just tricks founded on simple coincidence. So one is advised to be a little careful while sifting through the logic. But ultimately, the code is terse and fairly elegant.

Tags: signals, matlab, octave, software

## Design of LC Oscillators - Capacitive Overload

Jun 30, 2012

If the frequency was high enough, the capacitor in the tank would draw too much current from the output of the amplifier, and the amplifier would overload killing its gain and bringing the whole system down…

Tags: electronics