So… I got myself a Raspberry Pi. Well, actually two, but maybe we try to take it a bit slower and follow things in, more or less, chronological order.

So, again, I got myself a Raspberry Pi.
Why did I do it? Because I really like streaming. As I have mentioned in “Finally my TV does all the stuff I want” the first thing I do with a DVD after buying is ripping it in  order to be able to play it without having to use the DVD.
But I also don’t really like watching movies on my PC, which is where streaming enters the stage.

In order to allow my family to enjoy those movies while I’m not at home, equally without using and potentially damaging my precious DVDs, I used to leave my PC running, which of course consumes a lot of electricity, most of the time for absolutely nothing. And of course I was limited in my options switching between Linux and Windows (which I use for gaming) if somebody was watching a movie, or my family couldn’t watch movies because I was playing something.

These were the reasons I got myself a Raspberry Pi. In order for it to just run and wait for somebody to want to watch a movie.
The setup for this is remarkably simple, a stock Raspbian image, MiniDLNA for streaming, and NFS in order to manage the files remotely. That works pretty nicely, even for two concurrently running clients. I haven’t tested more than two clients yet, but I guess at a certain point you’re quite likely going to be running into the Raspy hardware’s limits.

Not too long after that I had the idea that at some point (which, as of this writing, has yet to happen) I could try to compile my little Linux distribution EasyLFS (most notably mentioned here) on it. That certainly is something I’d like to try, especially since through ARM I get to work on an architecture that I haven’t run my system on yet. Kinda like when I started porting EasyLFS to 64 bit. As said, this didn’t happen yet, but quite likely is going to happen at some point.

On we go to the second (and currently last) Raspberry Pi that I have purchased. But I would like to ask for a little patience, as I would like to artificially inflate this post by telling you a little bit of background story. If you don’t care, feel free to skip the next 4 paragraphs.

So, here we go…
As time and weather allows I like to spend a considerable amount of my evenings on the balcony, star-gazing. As I also like taking photos, usually scenery and animals, it was logical that I’d want to take photos through my telescope as well. I got myself an adapter to connect my EOS to the telescope, and actually managed to get a few recognizable photos of Jupiter.

But planetary photography of course wasn’t enough. While Jupiter is an impressive sight I also wanted to be able to go for stuff like the Andromeda Galaxy, the Orion Nebula and other things that I added a step-motor to my telescope, in order to allow longer exposure times by rotating along with the stars. That’s where the problems really started.

I had never really lost the feeling that the camera was too heavy, and that its mirror-switch might have an effect on image quality. In addition to that I found that at certain angles the weight of the camera would slowly push down the telescope, making long-exposure imaging impossible. The reason for this was simple, hanging the heavy camera onto the telescope completely trashed the careful balancing I previously had done, for simplicity, done without having the camera attached.

Finally, in addition to all this I was never quite happy that my camera limited in the infrared, because of that IR-filter cameras usually have. Before getting the Raspberry Pi I actually considered getting a used EOS on eBay and having it modified or getting a IR-sensitive CCD camera. Both options amounted to a couple of hundred Euro, which I considered a bit expensive for starting out. That’s when the Raspberry Pi came into play. It’s light weight would allow me to balance the telescope with the Raspberry attached, preventing drift, and because I’d just stick the camera on top of the regular eye pieces I’d have more flexibility in optical zoom, which I didn’t have with the direct connection I had with the EOS. Finding out that there’s a Raspberry camera without that annoying IR-filter of course made the whole idea even more interesting.

(Continue here!)
The whole hardware (board, case, camera, power supply and SD-card) came in at about 100 Euro and at 5 MegaPixels I’d get a good enough resolution to take nice pictures. Now I have to be able to control the camera, preferably without having to connect a thousand cables to my telescope. The idea was to do it remotely, that way I’d also be able to stay in the living room on cold winter nights while still being able to watch the stars.

So I fired up Eclipse and wrote a pile of PHP. A web-service that controls the programs raspistill and raspivid and returns their output. For raspivid that of course means streaming, which still needs a bit of work as I’m still fighting delays. The other end is a web-client which acts as the interface to the user, both in terms of control and output. And since I’m already at it I figured I’d also write an Android client; because I want to, and because I can.

The current state of affairs is that I can take photos and stream video from the Raspberry Pi to my browser. The former works quite nicely, the latter is not quite satisfactory yet. The Android client is practically non-existent. Aside from a few classes more or less resembling their PHP-counterparts there’s not much there yet. But once I get the networking-code tested and confirmed working I’ll get cracking on the UI-end of things. At a certain point I’m quite likely gonna publish this project, as I usually do with stuff like that. The whole code will probably join my other projects on SourceForge and the Android client quite likely is gonna end up on Google Play.
Another idea I’d like to try out at some point is having the Raspberry turn into a wireless access point if it cannot connect to my WIFI at home, thus enabling me to put my telescope somewhere in the middle of nowhere and connect to it using my notebook or tablet.

Aside from the coding work there’s also still a bit of hardware tinkering to be done. I need a proper way to fix the camera to the eye piece, the first couple of tests I actually did with the telescope involved a lot of scotch tape, which isn’t what I’d call a permanent solution. I also want to get a battery pack for the Raspberry Pi, as then it’ll be completely without any wires going to the telescope.

All in all I am pretty happy with this project, which I dubbed TelescoPi, and the first test-images I took of Jupiter, as mentioned with a very questionable setup involving several meters of scotch tape, look quite promising, and actually better than what I managed with my EOS, which has three times the resolution the Raspberry camera has.

The things I’ve seen through my telescope thus far are truly amazing, and I am really looking forward to the things I’ll get to see and photograph once the whole thing is working as expected.

So, coming to an end, I am actually a really happy Raspberry Pi owner. Those two little boxes are performing great, and provide a lot of fun. And I’m actually considering if one might be a suitable first computer for my son. But even if not, I’m pretty sure at some point there’s gonna be more than just two of those little thingies in our household.

Thank you!
Dennis Wronka

Advertisements