Replies to This Discussion

Permalink Reply by William on April 14, 2009 at 4:05pm

Nothing?

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Permalink Reply by Michael on April 14, 2009 at 4:15pm

My advice would be to wait and see. It hasn't been released yet and don't forget that Chris and Jordi have the same xbee modules as you, so I am sure there will be a guide or something similar if this is the case. It is probably more likely that the 2.1 code will support a modem up to 57000, not require it to transmit at this speed.

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Permalink Reply by Reto on April 14, 2009 at 4:37pm

I think you won't be left alone with this problem. Many probably have bought Pro XSCs in North America and Pro 868s in Europe. I'm in the latter case. The problem with both are lower bandwidth compared to the shorter range Xbee. In the case of the XSC, I wonder how they could be integrated fruitfully for other purpose than just little up or downlink. they have only 9600 bps throughput data rate. The 868 is a little faster, with 24000 bps RF data rate, but it is still not possible to burst data through them continuously. With both, if you push them too hard with the data stream, they stop transmitting and wait for cooling down. A way to have them up transmitting longer is to cool the square chip on them as low as possible. In the airframe, you may leave the module apparent on the surface, or stick a heatsink on it. As to the ground module, the way I'll do in summer is probably coupling it to a CPU ventilator.
But anyhow, those are not RF modules which could be used for flying a plane remotely from the ground. For this you need the faster Pro 900 with 156 Kbps RF data rate, or the Pro 802.15.4 with 63mw and 250 kbps RF data rate (1 mile range).
By the way, do you or others know what is inside the latest Graupner MX16 and Mx22 IFS bidirectional "transmitters"??? A 2.4 GHz Xbee module!!! They probably know why!

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ModeratorPermalink Reply by Chris Anderson on April 14, 2009 at 11:08pm

Here are a few answers:

First, we're using different Xbee 900 Mhz modules (air, ground), which support 56,000, unlike the ones you have.

The baud rate in ArduPilot 2.1 cannot be slowed down to 9600, since the code is optimized to read the GPS in binary mode at a higher speed.

But your problems will probably be solved in ArduPilot 2.2, which will return to an NMEA parser running at 9600.

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Permalink Reply by William on April 15, 2009 at 4:20pm

Thanks, That is indeed good news!

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Permalink Reply by Matt on April 15, 2009 at 5:41pm

Chris,

what is involved with hooking up the ground station module? I couldn't see any forum discussion for how we wire it all up.

Thanks

Matt

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ModeratorPermalink Reply by Thomas J Coyle III on April 15, 2009 at 6:01pm

Matt,

Try this: http://www.ladyada.net/make/xbee/configure.html

Regards,
TCIII

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