brainwagon

I’ve been doing a bunch of reading about digital ATV operations lately. I was originally motivated by hearing about the HamTV project aboard the ISS. Back in 2007, I got re-energized into ham radio by learning that for the 50th anniversary of Sputnik, the amateur satellite AO-51 would broadcast a cool message that I heard […]

I like it when my life’s experience and interests toss me an opportunity, and out of the blue last week I received an invitation to help with a class a colleague is trying to put together to help people build their own cameras, and he wondered if I could give an hour or so introduction […]

Nothing too exciting going on, but minor bits of code and play have been done, so I thought I’d update. First of all, there is a program for decoding SSTV on the Pi, called QSSTV. I don’t have a proper sound setup on the Pi yet, so I couldn’t test it live on the air, […]

Inspired by this webpage, I decided to write a simple zero-crossing analyzer, just like his. The code turns out to be remarkably simple, and would allow me to reverse engineer modes that aren’t adequately documented. I called this program “analyze”: [sourcecode lang=”C”] #include <stdio.h> #include <stdlib.h> #include <math.h> #include <sndfile.h> int main(int argc, char *argv[]) […]

Rob (AK6L) was interested in my recent experiments in slow scan television, but didn’t know much about color spaces. It’s an interesting topic on many fronts, and I thought I’d write a brief post about it here to explain it to those who may not be familiar. Consider this nice 320×240 test image of Wall-E […]

Previously, I had written an encoder for the Robot 36 SSTV mode. I chose this for a simple reason: it appears to be the most common mode used in downlinks from satellites, such as the ARISSat-1. It’s not a bad choice, and presents reasonable quality in just 36 seconds. Today, I decided that I should […]

So, this morning I played around a bit more with my Raspberry Pi code to try to see if I could make an SSTV beacon. The idea was to use two existing bits of code, raspistill and my own SSTV encoder (robot36), and glue them together with a small bit of Python. The code uses […]

Yesterday’s musings about SSTV using the Raspberry Pi has me thinking about creating a little SSTV beacon using the super-inexpensive (less than twenty dollars with charger) BF-888S HT from Baofeng. It’s hard to imagine a cheaper HT than this: it doesn’t even have a display. It has 16 channels, and announces which channel you are […]

Today I found an interesting Instructable on running SSTV on the Raspberry Pi. It uses an interesting bit of software which uses the Pi to directly generate an FM signal. Strictly speaking, I doubt this is a great idea without some outboard harmonic filtering, but it’s cool that it could be done. I recalled that […]

I’ve been taking a puppet making class, and I must admit, it’s been a lot of fun. Too much fun, in fact. I’ve been thinking about puppet making, watching puppet making videos, and scouring the web for inspiration and guidance. To date, I’ve only completed one puppet (his name is Gerfil, and he may still […]

A friend of mine was working on a programming exercise, and it turns it out was based on a chunk of math which I thought I should have seen before, but either have not seen or have forgotten. It’s basically that the products of all primes less than some number n is less than or […]

A while ago, Bill Meara from Soldersmoke brought Ashar Farhan’s new design, the Minima to my attention. The Minima is a general coverage transceiver which has a lot of cool features. It’s a superhet design which is Arduino based (actually, it incorporates a bare bones Arduino, which is little more than an Atmel ATMega328 chip.) […]

I’ve been playing around with the Raspberry Pi Camera for a number of different purposes, but one thing is pretty apparent right off: while the quality overall is quite good, it’s not very good in low light. Because at least part of my potential application is watching the night-time activities of wildlife (most likely my […]

First of all, let me get this off my chest: video over the web is a hideous Tower of Babel. With that basic complaint, let me start by saying that this project started with a Raspberry Pi and the Raspberry Pi Camera. Previously, I had used the Pi with a USB webcam and had connected […]

I was out running errands the other day, and found myself at Fry’s Electronics. I needed to pick up a VGA extension cable to replace one that had inexplicably become bad, and as I often do while wandering around, found myself doing a bit of window shopping. (Not Windows shopping, I’ve had enough of that.) […]