dword.dk

About a week ago I announced the initial release of my new small utility “dutree”. For an explanation of the purpose of the program, see the previous post. It was still missing an important feature that I wanted, namely gauges displaying the relative disk usage for the listed entries. This feature has now been implemented, and it is available in the new version 0.1.1. I also added an option for specifying a maximum depth for the listed entries. This makes it a lot easier to get an overview if there are many subdirectories and files. Click here to download the dutree source code.

I would like to announce that I have released a new simple command line utility that I call “dutree”. As the name suggests, it’s an alternative to du (a tool for summarizing disk usage), but it displays the results in a tree. This is not a big step up, I know, but I plan to add a column with gauges visually indicating the size of the entries compared to the total. I personally find that a much better presentation for getting a fast impression of the disk space used.

It’s a piece of software I have been missing many times in the past, but I never got around to implementing it. Now I used it as an opportunity for getting acquainted with some of the Boost libraries that I haven’t used a lot before. In particular dutree uses the following Boost libraries: Filesystem, Bind, Function, Lambda, and Iterator. I agree this might be a little overkill for such a small program (dependency wise, not performance), but knowing these very useful libraries makes for more effective development in other projects, so I think it pays off in the end.

This initial release is mainly for people who know how to build stuff themselves. A better build environment is planned for a future release. Click here to download the dutree source code.

Normally I wouldn’t write here about what I do at university, but this is so exciting that I have to share it — videos below. Since September me and my group at Aalborg University (AAU) have been working on a project called GENSO (Global Educational Network for Satellite Operations). It’s an international project supported by ESA, NASA, JAXA, and other space agencies, and lots of people participate. For our project this semester at AAU we’ve been developing a ground station server for GENSO.

Maybe a short introduction to what GENSO is about would help. A basic problem when communicating with satellites is that you’re only able to talk/listen to a satellite while it’s over the horizon. GENSO aims to solve that problem by establishing a network of ground stations all over the world which are connected via the Internet. Using the network you will be able to communicate with your satellite whenever it’s above any GENSO ground station, and not only your own. Better yet, the GENSO network will collect data from your satellite autonomously whenever it passes over a ground station, and send a pass report to you with the data received.

GENSO is in its alpha test phase, and only downlink is implemented, i.e. you can’t transmit. But still tracking satellites requires lots of stuff going on at the ground station, like predicting when satellites are passing, controlling antenna rotators and modems, and setting Doppler corrected frequencies on radios during a pass etc. This and more is what the ground station server is taking care of.

The cool thing about it is that now the project has reached a state where you can actually just start the ground station server, leave the server and the hardware alone, go somewhere else and wait for data rolling in once a satellite is over the ground station. We even implemented a live audio stream that you can connect to during the pass to hear what is received by the radio.

We already made a number of successful proof of concept passes at workshop V here in Aalborg back in early November. (Actually the picture to the right shows the participants at the workshop enjoying a celebratory roof-beer while the ground station is controlling the antenna behind us during a pass.) But not until now the system has been running completely autonomously exclusively on the hardware available at the AAU ground station.

What I’d like to show you is a couple of videos showing part of a CO-57 pass over the AAU ground station. I followed the pass from my computer at home, and no human interaction with the ground station was taking place.

Videos:
Video 1 (5.36MB) | Video 2 (33.2MB)

Pictures:

What you see on the screen in the videos and on the pictures above is: Upper left: Web-cam in the radio room at AAU. Lower left: GPredict running locally (just to see which satellites are available). Upper right: Debug output from the ground station server (setting azimuth, elevation, and radio frequency). Lower right: The GUI of the ground station server showing the passes that are scheduled within the next hour at the bottom. (The red bar to the left indicates the current pass.)

I’m still alive, although it’s been 5 months since my last post. I’ve been busy with university and work the last couple of months, so there hasn’t been much time for Ogre or other projects lately.

Anyway, just for the fun of it, I recently bought Olympus SDK to play with controlling my (rather old) C-5060WZ from the PC. It’s not the best piece of software I’ve seen, but it wasn’t that expensive either and seems to work just fine. It allows you to control much of the camera’s functions programmatically from the PC, i.e. setting focal length and lots of other settings, capturing pictures, and downloading/managing picture files etc.

Inspired by BBC’s Planet Earth, where they show e.g. plants growing in fast motion, I hacked together a small application capturing a picture of a small candle every 15 seconds. You can see a video of the result by clicking on the picture to the right of this text. The 33 seconds of video are made from 264 pictures taken during a period of about 1½ hour. Then there was no more space left on the CF card in the camera. Next time I’ll have to delete the pictures after having downloaded them - and find a more interesting scene.

I’ve updated my Depth of Field demo to support Direct3D in addition to OpenGL, and fixed a crash on ATI cards. Click here to download source code for Linux and Windows. There’s also a binary demo for Windows available.

Hi, and welcome to my new weblog. I figured using a weblog for maintaining a little site as this one would be a lot easier than hacking around with those old .html files all the time. So here it is. Still a bit work in progress, though.

To check out my software projects that used to reside here on the front page, just use the links under Software in the pages list to the right.