[Noisebridge-discuss] spacebridge balloon launch appears to have succeeded

Mikolaj Habryn dichro at rcpt.to
Tue Feb 9 20:24:25 UTC 2010


On Tue, Feb 9, 2010 at 11:48 AM, Mitch Altman <maltman23 at hotmail.com> wrote:
> Great photos!  And way interesting to watch the video pop out through the
> clouds.  :)  Is there a way to know how high up it went?  How did you get
> the cameras back?

We had two GPSes onboard. The one that was known to work above 60k
feet was connected to the APRS tracker and radio, but didn't log any
data locally. That was the single position report that we got at
around 61k feet.

The other GPS was internal to the Android phone, and, as we suspected,
it cut out at around 60k feet due to the common anti-cruise-missile
provisions. However, our Android code was also furiously logging all
the other sensors on the phone, including the accelerometer.
Processing this turns out to be a bear - it appears that either the
hardware or the interface software runs a smoothing filter over the
data before it's presented to the application, and we were running way
outside the envelope that it was expecting, so the data shows huge
discontinuities (eg, 1500 feet of vertical ascent in a second) between
smooth gradients which are probably largely fictional.

When the GPS cut out we were rising at at least 1200 feet per minute
(which is a good match for anecdotally reported terminal ascent
velocity for other people's launches), and the accelerometer data
(although also rubbish due to unknown noise sources) shows a definite
dip about 311 seconds later, so we're calling that the burst point.
a+b*c gives us about 67k feet with confidence, possibly above 70k
depending on how you process the noisy source data.

Next time I'll give you a more confident answer :)

m.

>
> Mitch.
>
>
> --------------------
>> From: dichro at rcpt.to
>> Date: Tue, 9 Feb 2010 10:00:34 -0800
>> To: rachel at xtreme.com
>> CC: noisebridge-discuss at lists.noisebridge.net
>> Subject: Re: [Noisebridge-discuss] spacebridge balloon launch appears to
>> have succeeded
>>
>> On Mon, Feb 8, 2010 at 11:15 AM, Rachel McConnell <rachel at xtreme.com>
>> wrote:
>> > I see where you got this camera thing sorted out:
>> > http://www.flickr.com/photos/genriel/sets/72157623376093724/
>>
>> Those are from the camera that our new best friends from
>> http://spaceballoonproject.blogspot.com/ provided, actually. The
>> camera I was asking about we just pointed down and started recording
>> video at launch - http://www.youtube.com/watch?v=go56JzqoFK0 - which
>> turned out so well (until it ran into a max filesize problem, grumble)
>> that I think we're just going to glue flip video cameras all over the
>> outside of the next one.
>>
>> (there's a longer version out there somewhere with a few minutes of
>> black screen with puzzled and slightly comic debate about how to
>> attach payload to a giant balloon - we weren't quite perfectly
>> prepared ;)
>>
>> > AWESOME PICS.  Anything up somewhere to read about this yet?
>>
>> http://dichro.blogspot.com/2010/02/declaring-weeks-advance-notice-of.html
>> is the first, I think. More will surely come.
>>
>> m.
>>
>> >
>> > Rachel
>> >
>> > Mikolaj Habryn wrote:
>> >> On Fri, Feb 5, 2010 at 10:55 AM, Martin Bogomolni
>> >> <martinbogo at gmail.com> wrote:
>> >>> Can't you roll back the firmware of the SD400 using the links provided
>> >>> on chdk.wikia.com?
>> >>
>> >> Not entirely sure - but will look into it tomorrow. Although the
>> >> firmware images are there, I didn't see a way of getting them onto the
>> >> camera.
>> >>
>> >> m.
>> >>
>> >>> On Fri, Feb 5, 2010 at 12:17 AM, Mikolaj Habryn <dichro at rcpt.to>
>> >>> wrote:
>> >>>> I bought a Canon camera off ebay to use on the spacebridge balloon
>> >>>> launch this Sunday, but it turns out to have a firmware version on it
>> >>>> that's too recent to work with CHDK (and therefore support time lapse
>> >>>> shooting). Does anyone have a superfluous Canon (compatible with CHDK
>> >>>> - list on the right-hand side of http://chdk.wikia.com/) that they'd
>> >>>> be willing to swap for this SD400?
>> >>>>
>> >>>> (I'd ask for a loan, but there's a reasonable chance of never getting
>> >>>> it back :)
>> >>>>
>> >>>> m.
>> >>>> _______________________________________________
>> >>>> Noisebridge-discuss mailing list
>> >>>> Noisebridge-discuss at lists.noisebridge.net
>> >>>> https://www.noisebridge.net/mailman/listinfo/noisebridge-discuss
>> >>>>
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>> >
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