Cheap long range communication?

Question

The communication would be used for communicating between a computer and a Raspberry Pi/arduino board. The range should be about 500m in city area, and the data rate some kB/s.

In the RF segment there is the xbee pro which would be perfect, but is a bit too pricy for this project.

On the other hand there is the GSM network. Which has a much higher range than RF and higher data rate. But the data is expensive.

What would be good communication solution?

EDIT1:

The location of the devices is not fixed.

EDIT2:

It seems that at that price range it is not possible to get a suitable communication system.

Making a custom RF system would probably cut down the costs, but how much work is it and what should one be aware when building/projecting it?

What data rate are you looking for at 500m and have you considered directional antennas and a much lower power output than xbee pro — Andy aka, Jul 24 '13 at 21:32
The location of the devices is not fixed, they move. So its not an option. Added this info to the question. — user2613971, Jul 24 '13 at 22:20
What exactly do you mean by "too pricey"? What is your cost requirement? — Joe Hass, Jul 25 '13 at 11:10
Sub 100$ would be nice to have. The project emphasis is on low cost. — user2613971, Jul 25 '13 at 16:00
If it was possible, and even cheap, to have clean wireless communication over 500 meters in the city, everyone would be doing it. And, at that point, it would no longer be possible. Everyone's receiver would pick up everyone else's transmitter from a 500m radius, resulting in chaos. 500 m in a crowded area is big enough that licensing is needed to reserve bands. — Kaz, Jul 29 '13 at 18:52
Ahem: http://electronics.stackexchange.com/questions/1149/wireless-communication-over-long-distances — John U, Jul 30 '13 at 08:15

score 2 · Accepted Answer · answered Jul 29 '13 at 21:20

Making a custom RF system would probably cut down the costs

No, it would not. Developing robust RF systems takes a lot of engineering, because it's a really hard problem. Digi, the maker of Xbee, can slice that cost across a large number of modules, so the cost-per-module is going to be very low.

However, if the budget is $100, then you can easily use two Xbee Pros. Even at retail, with external antenna, an Xbee Pro costs < $50 each, and you only need two to get a bidirectional link. Keep the data rate low (9600 bps, say) to keep distance long and interference tolerance high. Still, depending on the city, and the RF landscape, that may or may not be enough to do 500 meters.

If the Xbee is not sufficiently robust for you, the best option would be to go with cellular data, and pay the monthly charges.

Cheap long range communication?

1 Answers1