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Permalink Reply by wayne garris on May 17, 2008 at 11:38am

yes it would work but the baud rate is usually slow and you have to pay for the service. there is also the iridium system that can be used with cloudcaps AP . why do you say you can find this in a junk yard? is this what on-star uses?

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Permalink Reply by Cole on May 17, 2008 at 11:50am

If you look at some factory vehicles they come with factory XM Satellite Radio. A product similar to this one would be on vehicles (mainly GM) form about 2002 or 2003 onward. The easiest ones to get to are in Chevy/GMC trucks and SUV's, which are located right behind the glove box. At the same time you could use a TERK XM Direct box that you can buy at car electronics store as well, or at least I think you could becuase it does the same thing, basically.

So if I wanted to go with the iridium systems the ones on this page would be a better choice, correct?

http://www.satcomstore.com/satellite-modem.aspx

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Permalink Reply by wayne garris on May 17, 2008 at 1:05pm

the modems @ satcomstore look nice.but about a xm reciever im a little confused . xm is for one way com and if that was good for your uses how would you be able to send info to it ?wouldnt you have to be an xm broadcaster?im all for pulling hi-tech stuff out of junkyards , great place to find kevlar(airbags)

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Permalink Reply by Cole on May 17, 2008 at 2:35pm

Yeah I had always believed that Satellite Radio was a two way process (they need your radio ID to activate, so I just figured it would communicate this to their Satellites, oh well) so when I read the page at the link above, I made an assumption that this unit was a satellite radio transceiver, but I was obviously wrong.

However I did find a site that says you can make a gps receiver out of an onstar computer, so if I make a UAV about the size of a predator drone I can use it! :)

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Permalink Reply by wayne garris on May 17, 2008 at 3:12pm

sure but for $100 you can get a 32 channel 5 hz update unit .way better performance then what you will find on a car or cellphone ect . but sure you could make a junkyard uav , sounds cool !! i got a friend who hacks sattlite tv . its not two way, the signal is scrambled and you have to have a decoder.
the satellite modem @ satcom would work great for command and control but you cant send much info over them

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Permalink Reply by Tom Kent on May 27, 2008 at 7:31am

Unfortunately this modem works with orbcomm's network, which is not a real-time system. The way it works, is that a modem (such as the one you linked to) stores up data until a satellite comes within range. It will then upload its data to the satellite. The satellite will store the data onboard until it comes within range of a ground station, which can then downloads it from the satellite and sends it to you over the internet.

I'm not aware of any ability to send traffic in the opposite direction using Orbcomm's network, although the modem lists a set of receive frequencies in its spec, so that may be a possibility.

Though this system was designed for scenarios such as tracking shipping containers on the back of semis and such, it could be possible to use in a UAV for some many-hour flights. One possibility would be getting status updates from a UAV flying across an ocean, where there are obviously no ground stations to send telemetry to. If you want to do something like this though, you would need to be sure to coordinate your flight so that there are satellites in range at the appropriate times, and that they will have an opportunity for a downlink soon after the pass.

In my mind realtime systems such as Iridium could be far more exciting for UAV developers, especially when combined with standard cell phone network systems, so that you'd only be paying for satellite access when you really need it.

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Permalink Reply by johnsonrik on November 22, 2010 at 10:33pm

A "modem" stands for "modulator-demodulator". A satellite modem's main function is to transform an input bitstream to a radio signal and vice versa. There are some devices that include only a demodulator (and no modulator, thus only allowing data to be downloaded by satellite) that are also referred to as "satellite modems". These devices are used in satellite Internet access (in this case uploaded data is transferred through a conventional PSTN modem or an ADSL modem).

Flight to

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