why they put all the heavy crap like serial port on it and make huge pcb isn’t it suppose to be light

Posted at 3:25 pm on Jul 10th, 2009 by therian

I did something like that a few years ago… http://www.GeoCities.com/Almost_There_Weather_Balloon/

Posted at 4:12 pm on Jul 10th, 2009 by AlmostThere

There is something very off about that photo, like its a really bad photoshop job.

Posted at 4:44 pm on Jul 10th, 2009 by D

hehe.. i am working on something like this.

So far the plan is to have it relay back data optically via an RF based pointer (locks in on a local radio station)

Ideally it would use a mobile phone camera with a bit banging routine to write the data directly to an SD card with one of those 512kbit RAM 8 pin chips featured a while back.
Koff Saleae Logic /koff :)
-A

Posted at 4:54 pm on Jul 10th, 2009 by conundrum

“we are wondering if an implementation of the Nyquist sampling theorem is in use at all.”

I haven’t the faintest idea what you mean here. The balloon goes up, and then it hurtles back down. You only make measurements on the way up. Which frequency are you concerned about?

Posted at 5:18 pm on Jul 10th, 2009 by jeisch

“we are wondering if an implementation of the Nyquist sampling theorem is in use at all.”

“we” are wondering if you’re sure you know what the nyquist sampling theorem actually means…

Posted at 6:18 pm on Jul 10th, 2009 by hex4def6

That was snarkier than it had to be.

But your sampling rate doesn’t have to correspond in any way to your data storage rate. If you’re sampling a thermistor, and need one second intervals, you could be free to sampling it at 250ksps (or whatever), and do an averaging on it.

If you actually wanted to measure a frequency, then the nyquist thereom comes into play in terms of sampling rate. I doubt you’d want to simply capture the waveform though. it’d be much better to do an fft on it, and store the resultant amplitudes of the frequencies of interest.

Posted at 6:30 pm on Jul 10th, 2009 by hex4def6

I agree the photo looks wrong but I don’t think it was to be misleading. It looks like the photo was taken from the side, then stretched to provide a more top-down perspective…. or something like that.

Posted at 6:37 pm on Jul 10th, 2009 by MattieShoes

“we are wondering if an implementation of the Nyquist sampling theorem is in use at all.”

hihi,
you do not know that every sampler has already the Nyquist sampling theorem built in.
and that is free !

Posted at 7:32 pm on Jul 10th, 2009 by timour

The photo was resampled to 450×254. I could have cropped it but that would be lossy.

About the sampling theorem, i was just hinting around that periodic events are likely to alias which would render some of the data useless. I probably should have said something about sampling EM wave shifting to clear that up a bit.

Yes you could also do fourier transformation, if you have the cpu to back it up. In some cases you can cheat with power series approximations, if you don’t have enough cpu for hard realtime DFT/FFT and can justify a loss of precision /obviously based on the series terms/

It can be hard getting some of the ideas across on the blog without diving deep in the prerequisites. Anyway the thing is based on a Basicstamp so we can’t expect too much from it other than control.

Posted at 7:46 pm on Jul 10th, 2009 by Steve Watkins

Basically a single board computer tied to a balloon.

A better, and get this, easier, implementation can be done with parallax propeller chips; you could even drastically reduce board space and cost by using them.

A typical embedded CMOS camera censor is going to be useless for this without customized optics, and you can’t legally broadcast anything from it with out a high level ham license.

I’d personally use it for Digital Radio Mondiale research or signal rebroadcasting. It might be good for amateur climate research too on a budget.

Posted at 12:30 am on Jul 11th, 2009 by TJHooker

Test

Posted at 6:47 pm on Jul 11th, 2009 by cyry

The flight ocmputer isn’t all that heavy. It’s a concept board for larger and heavier BalloonSats. I have an article about in The Citizen Scientist. It permits several people/teams to design experiments and share a single airframe. The additional serial port allows a GPS to be connected so things like altitude data can be collected (something not often done on a BalloonSat mission). The image is taken at an angle and rescaled.

There are other, smaller designs on my website (these are kits) for single experiment, single team BalloonSats. Check nearsys.com/catalog

Posted at 1:14 pm on Jul 12th, 2009 by L. Paul Verhage

programming_pat@yahoo.com.au

Posted at 9:35 pm on Jul 14th, 2009 by lol