Is there any commercially available tiny (to be carried in model airplane) radio modems capable of communicating (full-dublex) at rate of 19200 baud (or faster) in a radius of up to 5km?
- posted
18 years ago
Is there any commercially available tiny (to be carried in model airplane) radio modems capable of communicating (full-dublex) at rate of 19200 baud (or faster) in a radius of up to 5km?
There are lots of things capable of many things, however what is IMPORTANT to know is
What country? This affects whether it is even legal to transmit at a suitable power level in that country for the distance or even enough bandwidth and modulation schemes for that baud rate.
Why 5km? As most countries have regulations about line of sight to model airplane that are radio controlled.
Why full duplex? You may be operating in bands that don't permit that for model aircraft.
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It may be that I live where there are very few trees, but I can see 5Km on any given day. Is there an actual distance limit in the U.S.
Brent S.
there appear to be radio modems on the license exempt 433MHz band which use
20-20mw. a search will produce lots of these products. if you have a directional aerial on the ground and a proper antenna on the other device, you will get the range if it is line of sight.i suggest that higher power could be used for the tx uplink where power considerations are less severe and a different frequency where interference is reduced to the plane.
note: lipd power limits are higher for some other freqs
For full duplex operation, you need two separate frequencies, one for uplink and the other for downlink. If you intend to put these frequencies on the same frequency band, you need very good filters to keep away the transmitter power from receiver. For sufficient selectivity, some form of cavity resonators would have to be used, which would be far too heavy for model airplane.
I would suggest using the aircraft control frequency (typically around
40 MHz depending on country) for uplink and perhaps 27 MHz or 2450 MHz for downlink, if it is allowed to operate airborne transmitters at these frequencies in your country.Paul
Check out the Xtream series of radio modems from MaxStream.
airplane)
I wonder whether you could hack a 900Mhz or 2.4Gig cordless phone. They work for a couple of km. No doubt, if you have them transmitting up in the sky, their range will be much better than on the ground.
Is this for a UAV project?
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