brainwagon

Well, I dusted off my checkers program source code and compiled it on my Mac. It managed to actually solve this position: a rather common one that checkers novices can’t often convert into a win. Black to move and win. My program seems to find the winning line, but only using a search significantly deeper […]

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 […]

It now can put out ground tracks as well as more detailed tracking information. Just a few more lines of code. ARISS will be visible from grid CM87ux starting in 01:36:47 at 23:08:11 23:08:11 +0.0° 210.7° ? 21.8°N 132.1°W AOS 23:09:00 +3.4° 207.9° ? 24.2°N 130.0°W 23:10:00 +8.5° 202.5° ? 27.0°N 127.2°W 23:11:00 +15.8° 192.4° […]

Well, my plan13 library has been joined with a library that decodes grid squares and the like, and another which downloads orbital elements and stores them in an sqlite3 database. The combination of all these allows you to write simple programs like the one I illustrate below, which gives predictions of the named satellites from […]

My old program for drawing globes made some nice postscript output, but in reexamining the source code, I can only imagine that I was doped up on cough medicine while working on it. I started a bit on a revamp of it, starting by purloining the matrix and vector library that I used in my […]

If you’ve listened to some of my satellite audio, you’ll notice that in addition to the callsigns, people are exchanging things that sound like “Delta Mike 41” or “Charlie Mike 87”. These are Maidenhead gridsquares: a system of rapidly transmitting your rough location. The kind most commonly heard are the ones that are 4 characters […]

I got a pretty good recording of the NOAA17 pass today, and converted it with my software. Turned out very nice. You can see Catalina and San Clemente Island off the coast of California. One of my better ones to date. Addendum: I didn’t use my Radio Shack scanner for this, I used my little […]

Well, I’ve made some headway on a project that I thought would be cool to write: porting G3RUH’s Plan 13 Satellite Prediction algorithm to a more palateable language than BASIC. I chose python, and it appears to be mostly working. It reads in the TLE orbital elements (same ones I use in “predict” or “gpredict”) […]

I can never remember these formulas, so I wrote this program. I’m putting it here so I won’t lose it, and so others may benefit. #include <stdio.h> #include <stdlib.h> #include <math.h> /* $Id$ * * Written by Mark VandeWettering. * * Any copyright would be pretty stupid. Use this code as you see * fit, […]

Well, during a road trip with my wife to San Diego and back, I managed to begin to type up my notes for an upcoming tutorial article (cross fingers) on reception and decoding of weather satellite imagery. I basically reimplemented what I had, stripping it down to its barest essence, and trying to make it […]

Yawn. Recorded another satellite pass. Decoded it with my software. Played with it in GIMP. Part of the pass spoiled by an oddly synchronous signal, which seemed to also be Doppler shifted. Problem on the satellite? I don’t know. NOAA17 Pass, Dec 14, 2007

Well, I was awake for a decent daytime pass of NOAA17, so I wandered out into my front yard, and recorded the pass. It was a westward pass, covering from Canada all the way down to Baja California in the south, and was reasonably noise free over a great amount of it. I hauled it […]

I haven’t had the time to record some of the NOAA17 passes during the day, but once night falls, I’ve managed to record a few passes. Tonight, I decided not to use my Yaesu VX-3R, but instead tried to record the pass from my old Radio Shack PRO60 scanner. While I recorded a bit less […]

A bit of image processing with gimp yielded the following on a night time pass.  It wasn’t particularly good with respect to noise:  on the night passes the contrast is pretty low , so you get difficulties  when you try to extract good images.  Still, I’m not displeased…

Okay, this isn’t that impressive, but let me explain. Larger version of the same… I recorded about 4.5 minutes of audio from one of the weather satellites, using my small pocket recorder and a Kenwood TH-D7A. In most respects, I shouldn’t expect anything good to happen. I’m using a cheap little voice recorder. I’m using […]