Archive for month: August, 2010

Les Météores, René Descartes

August 31, 2010 | Amateur Science | By: Mark VandeWettering

I was hoping to find a copy of René Descartes treatment of rainbows as part of Project Gutenberg (hopefully in English) but no dice. It does appear that the Université de Québec has the work Les Météores as part of their online collection. It’s far too late for me to work on reading it (my […]

Somewhere… over the (simulated) rainbow…

August 31, 2010 | Amateur Science, Computer Graphics | By: Mark VandeWettering

A few days back, I simulated how light propagated in a single drop of water, but with a number of problems. First of all, it didn’t simulate the Fresnel equations, which describe how light is reflected and refracted at the interface between two media. This meant that in my simple model, no light is actually […]

APRS experiment: OpenTracker + Kenwood TH-D7A

August 30, 2010 | Amateur Radio | By: Mark VandeWettering

On Saturday, I decided that the missus and I needed to do two things: get out of the house and get some exercise, and test my OpenTracker. So, I thought that we’d drive out to Mount Diablo, get a hike around, and then see how well the combination of my TH-D7A and the OpenTracker worked. […]

Khan Academy

August 30, 2010 | Amateur Science, Links | By: Mark VandeWettering

I’ve seen the Khan Academy listed a couple of times before, but never really bothered to look at it again until today. I was confused about a minor issue in linear algebra (hey, it’s been 25 years since I took linear algebra) so I surfed over and found the lecture on null subspaces to be […]

Hydropower generator

August 30, 2010 | Amateur Science, Link of the Day | By: Mark VandeWettering

On hack-a-day today, I saw this interesting link to a small hydroelectric generator. I’ve been interested in DIY/non-centralized generation of electricity for quite a while (without actually developing any serious knowledge about it, mind you) so I found the idea rather interesting. Paul taps water from a stream and uses it to feed a 2 […]

iHAB Iowa High Altitude Balloon

August 28, 2010 | Amateur Radio, Amateur Satellite | By: Mark VandeWettering

I was on the #hamradio channel on IRC this morning where people were watghing the progress of the Iowa High Altitude Ballon (IHAB) operating with callsign W0OTM-4. We saw it drift up to an altitude of about 88K feet, before descending. They had a 20m beacon, an APRS beacon running on 2m, and a cellular […]

Lightning, slowed down by a factor of 300…

August 27, 2010 | Science | By: Mark VandeWettering

0.3 seconds of real time, stretched out to 90 seconds of video. Very cool.

On light in drops of water…

August 27, 2010 | Amateur Science | By: Mark VandeWettering

A couple of days ago, I linked to an article which talked about using a laser beam as a kind of microscopic projector. The collimated laser light passes into a small drop of water, and then casts the image of protozoa (or other small swimmers) onto the wall. Very cool, but I wasn’t entirely sure […]

Morning Commute with OpenTracker+

August 24, 2010 | Amateur Radio | By: Mark VandeWettering

So, this morning I decided to give my OpenTracker another run, both to get a feel for how some of the parameters worked, as well as just trying to find out how complete the coverage is here in the Bay Area. For this test, I first modified the APRS symbol to stop being the balloon […]

Laser Microscope

August 23, 2010 | Amateur Science | By: Mark VandeWettering

An interesting impromptu project: a laser pointer directed through a drop of water projects a large magnified image on the wall. – Laser Microscope. This reminded me of the setup that Gabor described decades ago for inline digital holography. I might have to give this a try sometime. httpv://

A Project from the Past: My OpenTracker+

August 23, 2010 | Amateur Radio | By: Mark VandeWettering

Over a year ago, I blogged that I had assembled a bit of amateur radio gear, the OpenTracker+. This little gadget has a couple of DB-9 ports on it. The first is used to connect to a GPS, and the other to a radio, such as my Kenwood TH-D7A. Together, they form a tracker: the […]

Twitter Test

August 19, 2010 | General | By: Mark VandeWettering

A recent upgrade broke twitter updates on my blog. If you read this on twitter, it means that it’s working again. Addendum: Sigh. Still broken. Working on it.

Old Glory, in Postscript

August 19, 2010 | My Projects, Toys and Gadgets | By: Mark VandeWettering

I needed a graphic of a flag that I could scale to whatever size I needed. About 10 minutes of Postscript hacking with the specifications in Wikipedia yielded the following results: Sadly, the syntax highlighter that I have here doesn’t know about PostScript, so I’ll just have to add it here. %!PS % % % […]

Pictures of the Blum Blum Shub Random number generator…

August 18, 2010 | Amateur Radio | By: Mark VandeWettering

A couple of years ago, I did a post about the Blum Blum Shub random number generator. I was watching Psych, and bored, so I decided to just make a picture of the random bits generated when I generated two 50 digit primes. Without further ado, or explanation, check it: There do indeed seem to […]

CUSF Landing Predictor 2.0

August 16, 2010 | Amateur Satellite | By: Mark VandeWettering

Cambridge University has an amazing webpage that provides a web based front end to a weather balloon flight prediction program. It can even save output in Google Earth’s KML format. Very cool, very useful, saved for future perusal. CUSF Landing Predictor 2.0.