Posted by Jerald Brady on April 23, 2009 at 4:21pm
Hello all. I have been reading a lot of posts on these forums for awhile now as I'm trying to construct my own system which can send both flight data (speed, GPS data, etc.) and live video from the air. I am considering getting a 1.3GHz receiver and transmitter for the video from RangeVideo and a 900 MHz XBee Pro 900 for the flight data. I am pretty new to the entire radio frequency side of things though so I was writing to get some clarification.1) Do you need a Technician class radio license to operate any item in the 900 MHz band? What are the frequencies that are allowed for general public use (in the U.S.)?2) Is there a certain power level that is restricted without licensing? I read Technicians can go up to 1.5 KiloWatts but I'm not sure about general users.3) I am getting a video tx/rx on a different frequency from the flight data tx/rx because I was worried about interference. Is it possible to get them at the same frequency and not effect the transmissions?Thanks for all your help!!
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I believe the general rule for power is 10mw or less does not require a license, and you'll almost certainly need more power than that. Fortunately, the technicians license is very easy to get these days (no more Morse code), and there are plenty of online study guides.
As for frequencies, obviously it's best to use different freqs for everything, but that's getting hard to do. For example, I use 2.4 GHz for the radio, 900 MHz for video, which leaves me without a clear choice for the XBee.
Replies
Here's a chart that shows the US frequency allocation- http://www.ntia.doc.gov/osmhome/allochrt.pdf
I believe the general rule for power is 10mw or less does not require a license, and you'll almost certainly need more power than that. Fortunately, the technicians license is very easy to get these days (no more Morse code), and there are plenty of online study guides.
As for frequencies, obviously it's best to use different freqs for everything, but that's getting hard to do. For example, I use 2.4 GHz for the radio, 900 MHz for video, which leaves me without a clear choice for the XBee.
Rusty