[Space] aprs stuff

Christie Dudley longobord at gmail.com
Tue Jan 26 16:27:01 UTC 2010

Making comments inline.

On Mon, Jan 25, 2010 at 2:32 AM, <nils at shkoo.com> wrote:

> The Microamp 3 (http://www.byonics.com/microtrak/microamp.php) for $62
> looks useful to boost the radio output to 8 Watts.

I had been looking for something like this.  I'm kind of sitting on the
fence with it right now personally, though.  I think if we have a good
antenna with the right lobe pattern we should be OK.  If not... well, by all

Also, the TinyTrak 4 (http://www.byonics.com/tinytrak4/) for $75 looks
> like it has 5 analog inputs and 8 digital inputs.  It can include this
> data in the APRS reports, and has a builtin temperature sensor you can use
> for one of the inputs.  It looks polished and documented.
> On the downside, the tinytrak4 isn't open source (as opposed to
> opentracker+ I guess, where just the toolchain is closed source).

Yes, we'd talked about the tinytrak as well as the Opentracker+.  For this
go-round, we'll probably not be putting together a lot of sensors to feed
into it.  There's not only the concern that we won't get it back, but also
the fact that we have a very tight window to get this done.

Here are some other potential sensors, maybe not for the first run but
> they might supply some interesting data:
> http://www.sparkfun.com/commerce/product_info.php?products_id=9569
> http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=MPX5100A-ND
> http://www.sparkfun.com/commerce/product_info.php?products_id=8875

That geigertube looks particularly interesting.  We have discussed wanting
to measure radiation... on a subsequent run.  We plan to be making one of
these every month so there will be plenty of time to collect data.

It also might be worth including a beacon like one of these ($115) to help
> with recovery, like this one:
> http://bigredbee.com/BeeLine.htm

If we're talking about including a beacon, I think getting one of those that
they make for mountain climbers.  They sell for about $60 at HRO.  This is
particularly interesting to me, because I anticipate the antenna getting
smashed when it lands.  Of course, we probably need to know at least which
county it's landing in to get an idea of where to look for it.

If we have a dual-antenna USRP we can use with a chase team, that'll make
> the direction finding pretty easy.

How would this work better than the directional antennas I pointed out.
 Granted, we'd have to take a compass reading on these guys, but we should
get a really good idea, based on signal strength, of the "point and shoot".
 It's my understanding this is a popular solution for the "find the
transmitter" games they have at ham events.

> If we had 2 USRPs we could go a step further and do triangulation and get
> an estimated location instead of just a bearing. :)

Yes, but they'd need to be far enough apart to get good triangulation, which
would mean we'd need to be pretty far apart and close to the payload.  This
is why I suggested we build 2 of the unidirectional antennas.  What do you
think of those?

Here are some other do-it-yourself APRS trackers that might be useful for
> later launches, or just for general information on how APRS works inside:

Yeah, it's important to keep in mind that even though we pushed back the
launch date, we really only have 3 weekends left to prepare.  We still have
a lot of stuff to do.  It strikes me that our primary focus should be to
just get the stuff we know we'll need in and get it assembled, nailed down
and tested.  Although it's important to start talking about subsequent
launches and have stuff in the pipeline already for that.  I really like
that Geiger counter.

"The road of excess leads to the palace of wisdom." -- W. Blake.
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