[dorkbotpdx-blabber] Radio Gurus!

[dave madden]

Any radio gurus in the community? A bad, bad person told me some
interesting stuff about GPS, and now I'm wondering if it'd be possible
for me to learn more on my own, or if it's Black Magic that only old
ham-radio guys can understand.

For example, if I bought a MAX2654 amplifier and hooked it up to an
antenna, would I get anything interesting on the output? What
subsequent devices or equipment would I need to see the interesting
thing? How many steps from there to, say, a highly-accurate PPS clock?
(I don't mind dropping a do-it-all chip in, but I'm kind of interested
in having access all along the signal chain, too.)

Thanks!
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patents, copyrights & trademarks for engineers
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[Jared Boone]

On Jul 30, 2010, at 5:36 PM, dave madden wrote:

> For example, if I bought a MAX2654 amplifier and hooked it up to an antenna, would I get anything interesting on the output? What subsequent devices or equipment would I need to see the interesting thing? How many steps from there to, say, a highly-accurate PPS clock? (I don't mind dropping a do-it-all chip in, but I'm kind of interested in having access all along the signal chain, too.)

I'm so there! I'm happy to talk at length about disassembling GPS signals. To start with, have a look at this:

http://www.sparkfun.com/commerce/product_info.php?products_id=8238

A device that I believe downconverts the 1.575GHz signal to baseband and samples it at a few megasamples a second. It wouldn't be too difficult to build your own device to do something similar (and a lot of other fun things). In fact, I'm working on something that could do that...

Of course, they (GPS module manufacturers) are happy to sell you PPS-oriented GPS modules. Have a look at some of the U-Blox modules. But where's the fun in that?

- Jared

[dave madden]

On 07/30/2010 05:44 PM, Jared Boone wrote:

> http://www.sparkfun.com/commerce/product_info.php?products_id=8238

Interesting, but as a certifiable Cheap Bastard, it's not possible for
there to be enough stuff on a 1"x3" board that I'll fork out $450 for it
(whereas I'm pretty likely to fork out that much, or more, for the
opportunity to build such a board myself, and learn a lot in the process!)

Sounds like it's pretty close to the thing I want to end up with at the
end of the day, though.

> In fact, I'm working on something that could do
> that...

I am intrigued, and wish to subscribe to your newsletter... :-)

I'll look for you at the next Dorkbot Monday (or perhaps you should look
for me.) I'll be the guy with -- if I'm successful over the weekend --
a dummy LPC2148 isochronous USB device spewing data to a GTK app on an
Alienware laptop. And a beer. Definitely with a beer.

--
mersenne law llc -- www.mersenne.com -- IP law
patents, copyrights & trademarks for engineers

[Jared Boone]

Excellent. I'll be the guy you recognize as a Dorkbot regular but who never seems to talk to anyone. And I'll most likely have an alcohol-fortified cider beverage. And pie, if they have any this week... Mmmm, pie.

Oh, I know a few things about USB. So if your weekend project doesn't work out, perhaps we can put our heads together and fix it.

- Jared