Morse Code Reader

I wanted to make a Morse code reading application for some time now. Here's my first attempt, it listens to the signal through the phone's mic and translates it to text:



I'm sure there are all kinds of advanced signal processing techniques that I should be using, but for now I went with the simplest, most naive approach. And it sort of works, except when it doesn't. What I do is I keep an exponential moving average of the signal's volume and I decide that the signal is currently "high" when the average is above a threshold and "low" when it's below it. The threshold is set based on recent peak volume. Then I try to decide what the length of a dot and a dash is, interpret the input accordingly, and finally translate the dots and dashes to letters. The application adapts to changing volume and speed within reasonable limits (it should work up to about 40 WPM).



I was hesitant about putting the application on Android Market, as I only tested it on my phone and it quite often fails at translating Morse code. Then again, it's not like I have anything to lose by getting 1-star reviews and insulting comments, so why not.

Here's a Market link.

Page turner Mark II

I have improved my initial page turner design. Thanks to a third motor that repositions the rubber wheel between the left and right of the book, we can now turn pages in both directions!



The device is still manually operated and the problem of sometimes grabbing more than one page remains. But it is now less of a problem, because if we go a few pages too far, we can always go back.

Automatic page turner

Reading books is hard enough as it is. They're often long, boring and some don't even have any pictures in them. I decided to at least eliminate the physical effort of turning pages and constructed this little device:



At the moment it's not entirely automatic as I'm still controlling the individual motors manually (via Bluetooth from my phone, which is off-screen, because I'm also using it to shoot the video). The setup requires some tweaking for the exact size of the book and probably only works for a certain range of pages in the middle of the book. It also still sometimes grabs more than one page. But hey, it's a start. There's obviously room for improvement, for example it would be nice to be able to turn the pages in both directions. (Update: Here's an updated version that does that.)

NXT Remote Control

Two of my favorite toys right now are my Lego Mindstorms set and my Android phone. And thanks to the Bluetooth protocol I've found a way to combine them. Behold!



Since the video is quite blurry, here's a better view of the application's interface:



The third control scheme (not pictured), which I like to call the tank mode, allows you to control each motor separately and works best if your phone has true multitouch support (not just pinch-to-zoom).

Now I'm not saying my application is very unique, there are at least two others on the Android Market that do the same, including an official one from Lego. But hey, it's mine!

If you'd like to try it, below is a QR code that you can scan from your phone (or if you're reading this on your phone, just tap the code). And here's the application's AppBrain page. (It's free of course.)



Finally if you'd like to see the source code, it's over here at Google Code.

Paper clip spinning top

Today I'm going to show you how to make a spinning top from a paper clip. If you have a three year old niece or nephew, this is a trick you must learn.



You're going to need a paper clip and a pair of pliers. Also some cylindrical object is helpful, but not strictly necessary (I used a screwdriver handle). The paper clip can be any size, I used the bigger kind for demonstration, but the smaller ones work, too.



Supposedly the angle between the spokes must be 53 degrees for the center of gravity to be on the axis, but in my experience any roughly pac-man-like shape works. With a bit of tweaking you should get a top that spins for at least 30 seconds on a reasonably smooth surface.

Panoramic Quake 3

Running Google Earth on five screens is pretty cool, but we all know that the real test for any computer system is whether it can run Quake. Today I'm going to show you how to run Quake III Arena in a panoramic multiple screen configuration. Here's what my setup looks like:



And here's a video of me playing with some bots:



How do you make it work like that?

It turns out that it's actually easier than it seems, as Quake 3 already includes the view synchronization functionality, because it's needed for spectators. The only thing that we need in addition to that is a way to rotate the view a little to the left or to the right. This simple patch does exactly that, introducing a new console variable named cg_yawOffset.

You're going to need:

1. five monitors and five computers (or some other number)
2. a working copy of ioquake3 on each of them
3. my mod

(Technically, you don't need a separate machine for each screen, you could drive two or more screens from the same computer if you figure out how to make one instance of Quake 3 run in fullscreen on one monitor and another one on the other. Also, there's nothing ioquake3-specific about my mod, it's just that I used ioquake3 to compile it, so it uses the new QVM format, which doesn't work with vanilla Quake 3. If you want to make it work with vanilla Quake 3, you'll have to take my patch and compile it yourself.)

Unzip my mod and put the galaxy directory in your ioquake3 directory (it has to be on the same level as the baseq3 directory). Do it on every computer. The mod consists of QVM files and not native code, so it's platform independent and can't hurt your computer, so don't worry.

For simplicity I'm going to assume that you're going to play using the computer connected to the screen in the center, even though it doesn't have to be that way. The server is also going to run on it. On that computer, run ioquake3 with the following command line parameters:

+set fs_game galaxy +set sv_pure 0 +devmap q3dm7

(You can use some other map if you like.)

On the rest of the machines, just run ioquake3 as you normally would. Then connect to the server, either by typing \connect server_ip in the console (you'll have to know the server's IP address) or from the menu. Then become a spectator, by typing \team s in the console or from the menu (press Esc, choose start, then spectate). Then click the left mouse button (or whatever you have bound to +attack) until you're following the player from the master computer (center screen). All your screens should now be displaying the same view.

Time for the real magic. On each computer, type \cg_fov 45 in the console to set the field of view (use a number that matches the geometry of your setup, 45 degrees is what I used). Then on the first computer to the left of the master, type \cg_yawOffset 45. That will rotate the view 45 degrees to the left (if you used something other than 45 degrees for the FOV, use the same number here). On the second computer to the left, type \cg_yawOffset 90 and on the computers to the right, type \cg_yawOffset -45 and \cg_yawOffset -90. You should now have a nice panoramic Quake 3 configuration. Move around and see if everything works as it should.

You'll also want to disable the gun and the HUD on all screens except the master. To do that, type \cg_drawGun 0 and \cg_draw2D 0 in the console.

Oh, and by the way, if you don't have the full version of Quake 3, all of this works fine with the pak0.pk3 from the demo.

My ghetto Liquid Galaxy setup

Yesterday Google has published instructions on how to recreate their Liquid Galaxy immersive environment for Google Earth. Naturally I had to try it immediately. Unfortunately I don't have access to eight 55-inch monitors, so my setup is not quite as impressive as Google's, but still very neat:



Here it is in action: