Archive for month: March, 2008

Nifty “demo” on an unusual platform

March 31, 2008 | General | By: Mark VandeWettering

There is a segment of the computer art culture which works on creating “demos”: short bits of combined computer animation and music which play on computers. They are often praised for being clever and short. They seemed to start back during the time of the Commodore 64 and other 8 bit computers. But check out […]

Homemade Transistors?

March 29, 2008 | Amateur Radio | By: Mark VandeWettering

My excursion into nostalgia has me researching homebrew transistors and tubes. Today, G3CWI mentioned this article about homebrewing transistors on the GQRP list. The method isn’t quite as “from scratch” as I would like: it basically uses the innards of a diode to make a point-contact transistor. Something that comes a bit closer to real […]

Internet Archive: The Radio Amateurs Hand Book (and more)

March 28, 2008 | Amateur Radio | By: Mark VandeWettering

Here is a link to Frederick Collins’ 1922 version of The Radio Amateurs Hand Book. Neat. Addendum: Radio telephony for amateurs also appears pretty cool. It was published in 1922, and includes a circuit for a regenerative receiver, which I recall was invented only around 1917. Addendum2: Can you tell I’m on a crystal radio […]

Working the QRP repeater on AO-51…

March 25, 2008 | Amateur Radio | By: Mark VandeWettering

This week, the powers that be have enabled the second repeater on AO-51 for use. Uplink is on 145.88 and the downlink is nominally on 435.150 in addition to the 145.92 and 435.300 which are its normal frequencies. Apparently not a lot of people know about this schedule change though, because the only person I […]

Bunny Torture…

March 23, 2008 | Link of the Day | By: Mark VandeWettering

Not real bunnies. Just chocolate bunnies. Happy Easter.

Low western pass of AO-51…

March 23, 2008 | General | By: Mark VandeWettering

I worked the fifteen degree pass to the west of AO-51 tonight. Not all that great, was hoping to get someone from Hawaii, but alas, nothing doing. Still, I got WB6YTE (whom I’ve worked before) and N7JK (who I don’t think I’ve worked before). Considering the low pass, my hand held arrow, low power and […]

I’m genuinely sad….

March 22, 2008 | General | By: Mark VandeWettering

I must admit, part of my fascination with computers and mathematics has to do with my early exposure to Martin Gardner’s absolutely fantastic Mathematical Games columns in Scientific American. As a grade school student, I remember reading these columns and through them, discovering for the first time the actual excitement of mathematics. It’s hard to […]

The FFT Demystified

March 21, 2008 | Math | By: Mark VandeWettering

Here is a good explanation of the FFT. I have used FFT libraries before, but I never really bothered to code one myself. The FFT Demystified.

HF SDR receiver designs…

March 19, 2008 | Amateur Radio | By: Mark VandeWettering

This link came across the softrock mailing list. Preserved for its many cool ideas! HF SDR receiver ideas from YU1LM

Courteous AO-51 Operation

March 18, 2008 | Amateur Radio | By: Mark VandeWettering

I like working AO-51. It’s the easiest of the easy satellites, with strong signals, little fading, and is workable with small handheld antennas or mobile rigs of the sort that many hams already have. Unfortunately, it’s not always the most courteous place to operate. All sorts of impolite operation seems to be the norm, especially […]

Jörg’s useful and ugly FXT page

March 17, 2008 | Computer Science | By: Mark VandeWettering

Well, my excursion into FFT multiplication the other day left me with some more interesting questions, including trying to find out more information about the integer version of the FFT called the NTT (number theoretic transform). Instead of computing the transform to an orthogonal basis consisting of the complex roots of unity, the NTT transforms […]

Sunday Afternoon AO-27 Pass

March 16, 2008 | Amateur Radio | By: Mark VandeWettering

It has been quite some time since I worked AO-27: the passes usually occur in the early morning and early afternoon, which isn’t all that convenient for me. But today I happened to be around for the pass, so I gave it a try: March 16, 2008 pass on AO-27 Worked W6ZQ, DM42 (which I […]

2^32582657-1 is prime

March 15, 2008 | Math, My Projects | By: Mark VandeWettering

In fact, at the moment, it’s the largest known prime, with over 9.8 million digits. As part of my pi day celebration yesterday, I was trying to review how I might speed up my C code which calculates pi to large numbers of digits. Most of the fast ways rely on fast multiplication, utilizing the […]

Tomorrow is pi-day….

March 13, 2008 | Math | By: Mark VandeWettering

Tomorrow is 3/14, known as pi day, or Albert Einstein’s birthday. How better to celebrate than with a script in pi-thon? #!/usr/bin/env python from itertools import islice def g(q, r, t, i): while True: u, y =3*(3*i+1)*(3*i+2), (q*(27*i-12)+5*r) // (5 * t) yield y q, r, t, i = 10*q*i*(2*i-1), 10*u*(q*(5*i-2)+r-y*t), t*u, i+1 def pig(): […]

AO-51 pass…

March 12, 2008 | Amateur Radio | By: Mark VandeWettering

Nice high pass this evening, got a few people. Pass seemed a bit tougher than normal, I was waving the antenna around alot trying to get the best polarization. Worked: N6TWW CM98 Mike K7WJS DM41 KI6NUG Heard WB7AEA, but he seemed deaf to my appeals…. AO-51 on March 12, 2008