OFFICIAL - 2011 UAV Outback Challenge Forum - Page 20 - RC Groups
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Aug 14, 2011, 10:16 PM
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Quote:
Originally Posted by BazDaddy
Im SO interested to see how this works out for you guys! Please keep me posted!
We certainly will! We happen to have someone on our team who works with a WISP using these modems for long range links, and he has got good stability. We are also building an antenna tracking system for the ground station, and we are probably also going to have some sort of tracking in the plane.

If we end up with an omni in the plane then we'll at least use a servo to keep it pointing straight down. We're also investigating the possibility of small directional antennas that we could use in the plane to get full tracking.

I'll post details on my blog or our mailing list as we do tests.

We won't be completely reliant on this link however. We will also have a 900MHz link and will be able to complete the mission with just that. It would just mean we wouldn't have a video stream, and we'd only have low-res versions of the images the cameras are seeing at the ground station.

Cheers, Tridge
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Aug 15, 2011, 03:30 AM
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What radios are you using for your 900mhz link?
Aug 15, 2011, 03:46 AM
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Quote:
Originally Posted by BazDaddy
What radios are you using for your 900mhz link?
We're still deciding on that. We've got Xbee900Pros, but those don't have the range we want. We also have some larger 900MHz radios that one of the team members had from a previous project (I don't know the name of them, sorry, they are ones used for a surveying project he worked on). Those radios have a serial interface, like the Xbees do.

We're also considering getting the ubiquity RocketM900 radios. Those would give us some good bandwidth on 900MHz, and we've been very impressed with the 5.8GHz ubiquity radios, so going with the same brand for the 900MHz link is tempting. The downside is that its ethernet, and we had planned on having higher robustness by making the 5.8GHz be an ethernet bridge, while using serial direct into the APMs for the 900MHz. That would mean that even if our pandaboard died completely in flight, we'd still have control via the 900MHz link (the pandaboard is the one with the ethernet interface and connection to the ethernet switch). The M900 is quite heavy, but our Mugin can carry a big load. Maybe we'll end up with an ethernet to serial adapter and the M900s. Or maybe we'll just do both links into the pandaboard and rely on the DroneCell for direct link into the APM should the pandaboard die.

So it's fair to say that we're not completely sure which 900MHz radio we will use yet. Suggestions are welcome!

Cheers, Tridge
Aug 15, 2011, 03:56 AM
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chancesAU's Avatar
I use XTend 900 modems, tracked my plane down into a pine forest one day, lucky to get it back. Last GPS coord's were within 1meter of the UAV.
Omni's on both ends.
Aug 15, 2011, 04:02 AM
Registered Crasher
Bilox's Avatar
Quote:
Originally Posted by chancesAU
I use XTend 900 modems, tracked my plane down into a pine forest one day, lucky to get it back. Last GPS coord's were within 1meter of the UAV.
Omni's on both ends.
You can get them from here with C-tick!
Aug 15, 2011, 04:50 AM
Registered User
tridge

are you using the standard 50mw pro 900 xbee? I was looking at getting the XBee Pro 900 XSC RPSMA they have the 100mw radios in them. what sort of range were u getting out the 50mw ones?

thanks for the link biloxthecat, do you have any idea on the price as they dont have that on the website?
Aug 15, 2011, 04:59 AM
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Bilox's Avatar
Quote:
Originally Posted by BazDaddy
tridge

are you using the standard 50mw pro 900 xbee? I was looking at getting the XBee Pro 900 XSC RPSMA they have the 100mw radios in them. what sort of range were u getting out the 50mw ones?

thanks for the link biloxthecat, do you have any idea on the price as they dont have that on the website?
Can't remember exactly, I think they were around $220 ish? (2009)
Aug 15, 2011, 05:00 AM
Registered User
also where are you getting your Mugin kits from?
Aug 15, 2011, 06:05 AM
Registered User
Quote:
Originally Posted by BazDaddy
tridge
are you using the standard 50mw pro 900 xbee? I was looking at getting the XBee Pro 900 XSC RPSMA they have the 100mw radios in them. what sort of range were u getting out the 50mw ones?
yep, we have the 50mW ones. We haven't done long range testing on them, as we really don't think they will be good enough for the range we need for the competition, so we've been concentrating on testing the 5.8GHz radios so far (even with those we've only tested to 5.2km so far).

Cheers, Tridge
Aug 16, 2011, 03:09 AM
Registered User
Team TGIF will also be using XTend 900 modules for telemetry. The manual we have ( http://www.sparkfun.com/datasheets/W...ductmanual.pdf ) and on page 70 states that the conditions of the c-tick certification: "Regulations in Australia stipulate a maximum of 30 dBm EIRP (Effective Isotropic Radiated Power). The EIRP equals the sum (in dBm) of power output, antenna gain and cable loss and cannot not exceed 30 dBm." Just though you'd all like to know. :-)
Buzz (TGIF Team Leader).
ps... <hi everyone>
Aug 16, 2011, 08:40 AM
Registered User
Quote:
Originally Posted by davidbuzz
Team TGIF will also be using XTend 900 modules for telemetry.
I'm curious what you and others are using for video. The 5.14 request for a video stream is partly what prompted us to into go down the IP video route. If other teams aren't doing IP video, then what are you doing? I guess you could do a low power analog video transmission (carefully choosing power and band to meet the regulations and avoid your telemetry/command frequencies) and use a big antenna on the ground to pick it up. Is that how you are doing things?

Cheers, Tridge
Aug 16, 2011, 08:58 AM
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TeamSAR_2011's Avatar
We use COFDM technology for video and 900mhz for command and control comm.
Aug 16, 2011, 10:51 AM
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What COFDM system are you using?
Aug 16, 2011, 04:14 PM
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mboland's Avatar
Quote:
Originally Posted by TeamSAR_2011
We use COFDM technology for video and 900mhz for command and control comm.
What frequency ( and class license ) are you using for your COFDM?
Aug 17, 2011, 12:57 AM
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Dr Strangelove's Avatar
Quote:
Originally Posted by davidbuzz
Team TGIF will also be using XTend 900 modules for telemetry. The manual we have ( http://www.sparkfun.com/datasheets/W...ductmanual.pdf ) and on page 70 states that the conditions of the c-tick certification: "Regulations in Australia stipulate a maximum of 30 dBm EIRP (Effective Isotropic Radiated Power). The EIRP equals the sum (in dBm) of power output, antenna gain and cable loss and cannot not exceed 30 dBm." Just though you'd all like to know. :-)
Buzz (TGIF Team Leader).
ps... <hi everyone>
You may also want to have a think about teh number of hopping channels. The channels that are permissable to hop over there on some 900s are not the same as those permissable to hope here on 900.

Dr S


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