Long Range Wireless Data Transmission

wolverine171 said:

I want to perform wireless communication between two microcontrollers. The distance that I am looking at is around 15-20 km. I have a string of data to be transmitted (need not necessarily be continuous).
One of my microcontrollers attached with the transmitter will be outside/roaming and the one at the receiver end would be stable.
I have been looking out for a few things and came across these two..
1. XBee Pro 900 XSC Wire - 15 mile range
2. XTend 900 1W RPSMA - 40 mile range

My question is that will this solve my data transmission problem ? and if anyone of knows a better module, can you please guide me.

---------- Post added at 03:13 ---------- Previous post was at 03:12 ----------

I am planning to use Arduino board

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• Ranges stated on promotional material are typically for line-of-sight with NO obstructions. This means that having the receiver radio inside your house (where the signal has to pass through walls) will decrease the data link's effective range.

• If your system is bi-directional (devices require handshaking in the protocol), then your system must be reciprocal (transmitter must be as strong as the receiver, so they can both be the "transmitter" during the exchange of data).

• If your system is uni-directional (transmitter only transmits; receiver only receives) then the transmitter needs to be high powered. This way, the transmitter creates a strong enough signal to cover the distance between the devices, and that the resulting signal at the receiver has a decent SNR. The better the signal-to-noise ratio, the more likely the receiver can correctly demodulate the data. In this scenario, the receiver doesn't ever transmit (uni-directional), so it doesn't need to have a (big) transmit amplifier (i.e. lower effective range).