Archive for month: September, 2011

Apologies to Ken and Eric re: SSTV Challenge…

September 29, 2011 | Amateur Radio, SSTV | By: Mark VandeWettering

My face is red. I had claimed yesterday that nobody had tried to decode my SSTV challenge, when in fact both Ken and Eric decoded it. Eric was the first, who sent me this decode: It’s a bit noisy, because he just played the sound file on his laptop and decoded it on a PC […]

An impractical classic SSTV decoder…

September 28, 2011 | Amateur Radio, SSTV | By: Mark VandeWettering

A few days ago, I posted a .WAV file for a classic 8s SSTV image and asked if anyone could decode it. Nobody replied (I wasn’t surprised) so I set about writing my own demodulator. Since I’m inherently lazy, here was my idea: generate the complex signal using my previously debugged Hilbert transform code. Then, […]

Difficulties with the Hilbert Transform…

September 28, 2011 | Amateur Radio, Math, My Projects | By: Mark VandeWettering

Well, it wasn’t so much a difficulty with the Hilbert transform as a difficulty with my understanding. But with the help of my good friend Tom, my understanding was soon put right, and I thought it might make an interesting (in other words, horribly boring to anyone but myself) post, and at the very least, […]

Classic Black and White SSTV timings?

September 26, 2011 | Amateur Radio, SSTV | By: Mark VandeWettering

I was trying to determine the exact timings for the classic “8 second” black and white SSTV mode. Copthorne MacDonald suggests 15 lines per second, to make 120 lines in 8 seconds. The vertical sync pulse has a duration of 30ms, and the horizontal sync pulse duration is just 5ms. The sync frequency is 1200Hz, […]

“Classic” Black & White SSTV…

September 25, 2011 | Amateur Radio, SSTV | By: Mark VandeWettering

I haven’t had much time for actual experimentation, but I have spent some time researching and some more time thinking about how to properly implement and test analog SSTV modulators and demodulators. I haven’t made much actual progress, but I thought I’d document some of the information that I’ve discovered and my current thoughts. First […]

Experiments with SSTV in the presence of noise…

September 20, 2011 | Amateur Radio, SSTV | By: Mark VandeWettering

Last night while watching television, I decided to code up an SSTV modulator for the most popular US mode, which is reportedly Scottie 1. I had done most of the heavy lifting when I created a Robot36 encoder a few years ago, so I mostly cribbed the meat out of that code, and modified it […]

Thoughts on SSTV…

September 19, 2011 | Amateur Radio, Amateur Satellite | By: Mark VandeWettering

My recent playing with SSTV images coming from ARRISSat-1 have made me think a bit more about SSTV. I used two different applications to decode SSTV images (MMSSTV on Windows, and Multiscan on OS X), and got slightly different results in terms of performance from each. This leads me to ask “just what are the […]

Word Foto

September 15, 2011 | Photography, Photos | By: Mark VandeWettering

Courtesy of a new $1.99 app called Word Foto, I give you:

NOAA 19 recording, and atpdec…

September 14, 2011 | Amateur Radio, Amateur Satellite | By: Mark VandeWettering

Some of you may remember that I wrote my own APT satellite decoder. I ran across someone else who did the same: ATPDEC by Thierry Leconte (F4DWV) It has the same basic philosophy as my own crude efforts: hand it a WAV file, and it will find and produce the APT imagery from inside it. […]

Shortwave Pirate Radio

September 14, 2011 | Amateur Radio | By: Mark VandeWettering

I got pointed at this rather large collection of shortwave recordings which are archived on the website: Shortwave Pirate Radio : Free & Unlicensed Shortwave Radio Stations : Free Download & Streaming : Internet Archive They have many crazy recordings of radio pirates, some of which are pretty dull, but some of which were […]

Can we go beyond WSPR? An idea for beacon operations on amateur radio.

September 13, 2011 | Amateur Radio, Cryptography | By: Mark VandeWettering

I was interested in WSPR and visual MEPT oeprations for quite some time. I operated both a beacon and a QRSS aggregator on 30m for a while, but I grew a bit tired of it, and it’s been silent for a year or so. But I haven’t stopped thinking about them. In fact, I’ve had […]

Digital Research CP/M ® Operating System Manual

September 11, 2011 | Emulation | By: Mark VandeWettering

I found this manual to be informative as I continue my quest to making a properly functioning 8080 emulator. I’m learning lots, but still not quite there. This is just bookmarked for future reference. Digital Research CP/M ® Operating System Manual.

Morning ARISSat-1 SSTV

September 11, 2011 | Amateur Radio, Amateur Satellite | By: Mark VandeWettering

I overslept this morning, and woke up a scant 10 minutes before this morning’s good pass of ARISSat-1 was to begin. Still, all I had to do was go out to my car, grab my Arrow, and my HP laptop, and my trusty VX-3R, and I should be able to make it. I started pulling […]

8080 bottles of beer…

September 10, 2011 | Emulation | By: Mark VandeWettering

Okay, not 8080 bottles, but 99 bottles of beer anyway… [proof:~/adad] markv% ./adad ::: brainwagon 8080 emulator version 1.0 ::: 637 bytes of code loaded. 99 bottles of beer on the wall, 99 bottles of beer. Take one down, pass it around, 98 bottles of beer on the wall. 98 bottles of beer on the […]

Intel 8080 CPU Emulator (in Javascript, no less)

September 9, 2011 | Emulation | By: Mark VandeWettering

After getting a version of Tiny BASIC running on my emulator, I was scanning around to try to find something else to run. And, of course, when you look, you find all sorts of cool stuff. I happened across this cool page which is an 8080 emulator which is written in Javascript, and runs entirely […]