SparkFun Forums

[lapa678]

Hi there !

I'd like to ask you if you have any ideas for doing long range beacon. I'm mean just RF impulse of something, range about 5km, just to indicate presence ...

Is this simple task ? Any ideas ? I'll appreciate any help!
Cheers.
Tom

[stevech]

In the United States (FCC regulations) ...

I'd suggest using the unlicensed MURS band. It's VHF (good propagation in urban clutter) and permits several watts. THere are some modem boards available for $150 or so.

Second choice would be (in the US) the unlicensed 902-928 MHz band. With a yagi antenna and the 1W radios from Maxstream/Digi, you can get that kind of range, though not omni-directional.

[ke7eha]

YOu could use an APRS system. It includes position data, and relays for longer range potential. You will need at least a technician class amateur radio license, but getting one is very easy.

[lapa678]

Thanks for reply folks!
Isn't there some easier and cheaper solution for sending just a beacon ;p ?

I don't want to spend more then 150$ on system which allows me to send lots of data. But still, your ideas got me thinking though - thanks for reply!

Cheers,
Tom

[maokh]

Don't let the fancy FCC "MURS" band scare you.... they are just a handful of 151MHz frequencies right above the 2 meter ham radio band..The same band that contains the "color dot" frequencies or "(VHF) business band".

Its full of trash and noise, so don't expect to be the only one on the band. This could be good or bad. If you are outside of dense urban areas, its a bit more open.

You could build/modify an inexpensive transmitter that was fixed, maybe even crystal controlled, that transmitted a tone. You could even do CW for maximum "range" instead of a tone over FM. More power per Hz.

Your starting point would be the plethora of ham radio "fox hunt" or beacon designs and tuning it a few MHz higher. There are also a lot of existing ham radio boards that could be modified to operate on MURS since the bands are so close. A couple of recent handhelds even work on MURS and the ham band.

Also, a lot of companies are quite literally throwing away MURS gear and moving over to new digital systems, such as motorola's 900MHz digital radio system...