Tiny 19200 baud 5km radius radio modem - Page 2

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Re: Tiny 19200 baud 5km radius radio modem



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There are a number of small spread-spectrum systems that will do this,
but only line-of-sight. They are very expensive though.

Re: Tiny 19200 baud 5km radius radio modem



"swanny"



 **  Why did you reply to my post instead of the  OP's ??




..........  Phil



Re: Tiny 19200 baud 5km radius radio modem


On Thursday, in article

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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.

--
Paul Carpenter          | snipped-for-privacy@pcserviceselectronics.co.uk
<http://www.pcserviceselectronics.co.uk/ PC Services
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Re: Tiny 19200 baud 5km radius radio modem



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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.


Re: Tiny 19200 baud 5km radius radio modem


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

 

Re: Tiny 19200 baud 5km radius radio modem



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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


Re: Tiny 19200 baud 5km radius radio modem



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Check out the  Xtream series of radio modems from MaxStream.
http://www.maxstream.net



Re: Tiny 19200 baud 5km radius radio modem



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airplane)
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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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