Happy New Year, everyone!
I'm trying to build a helicopter and now I'm thinking of the way to control it.
So, as far as I understand, if I have any RF link or a zigbee module, I'll put a receiver on a helicopter, connect it to Arduino and read data from it. What I don't understand is what is going to transmit data to the receiver..? Is it another Arduino, connected to the transmitter, or is it a special device? Or may be I can send signals straight from my laptop, if I'm going to use a wi-fi module, for example...
Can anyone clarify this stuff for me.. Thanks a lot.
You would use something like an arduino reading the positions of potentiometers representing the positions of the helicopter controls and transmit that to a receiver on the helicopter.
It depends on the transmitter and receiver you use.
A system-on-a-chip (like the XBee) which was a transmitter and receiver, analog input, digital input and digital output can work
without an additional uC. Using the Arduino makes it a easier
to program.
I have been making a board that combines an Arduino compatible
design with an XBee. See
http://wiblocks.luciani.org/ZB1/ZB1-index.html
There are some transmit and receive software examples on the site.
I would also recommend the O'Reilly book "Making Things Talk".
This book describes different wired and wireless ways to "make things
talk" (and listen 
(* jcl *)