Thanks for all the replies
In terms of the data, its really just basic on / off commands for now, nothing fancy yet (till I learn)
But I would like multiple transmitters / receivers running (with in about 10m of each other, so I don't want 1 pair triggering a pair on a different system. Likewise, the neighbors wont be happy if the signals start interfering with the TV or wifi etc. lol
I dont know enough about RF to know if my concerns are valid
Rusty, okay, that is clearer now. Basic on/off stuff. Why not have a look at
http://www.rapidonline.com/Electrical-Power/AM-FM-System-Modules/Transmitters-Receivers and download some of the datasheets - you can a lot from browsing through these. Then, as you come across aspects that are unclear, do as Stan suggests and research the topics on the internet. A basic radio switching unit such as
http://www.rapidonline.com/Electrical-Power/AM-Transmitters-and-Receivers-for-Embedded-Radio-Control-122241 will be easy to understand and to implement. You can interface the receiver to a PICAXE chip very easily and that will give you the pairing of transmitters and receivers that you are looking for, it should not interfere with any other equipment and the units will definitely not trigger each other unless you have paired them up. You can set up an arrangement with one-to-one; many(transmitters that is)-to-one(receiver) or one-to-many. All you have to do is to ground the "learn" pin on the receiver, press a button on the transmitter, watch for acknowledge LED on the receiver and the pairing is complete. The devices have all the security of a remote car lock...which is pretty much what they are! Like remote car keys in multi-story car park, the remote will trigger the receiver and not interfere with anyone else. Range is 100 metres or so, less of course inside a building.
Now that is a cast-iron way of getting the pairing etc. done for you and, as you are using certified transmitters and receivers you are safe from messing anybody else around with spurious transmissions. But that route will get a system working quickly; you may not get a lot of understanding of radio data transmission out of it. If you want to learn more about the basic methods, then buy a simple serial transmitter and receiver pair such as
http://www.picaxe.com/Hardware/Add-on-Modules/433MHz-Radio-Transmitter-and-Receiver-Pair/ and match these up with the circuit kit
http://www.picaxe.com/Hardware/Add-on-Modules/RF-Connect-Radio-Boards/.
If you use a simple transmitter with a serial interface you can use a preamble, referred to as a qualifier, in the serial data sent to ensure that the receiver - or at least the PICAXE that is connected to it, will only respond to the proper data. Have a look at the Serial in command in PICAXE MANUAL 2: SERIN pin,baudmode,(qualifier,qualifier...),{#}variable,{#}variable...
Then internet learn about Manchester Encoding. This is a method that reduces errors in transmitted radio data. You can find out more about this in the PICAXE datasheet
www.rev-ed.co.uk/docs/axe213.pdf where you will learn about a chip that does the Manchester Encoding - the NKM2401.
Now you will understand more of the methods of sending RF data and ensuring accurate reception, this will take you into the latest PICAXE way of doing things using the RFOUT and RFIN commands, whereby the Manchester encoding is done by the PICAXE.
Also, have a look at the latest PICAXE transceivers the ERF units -
http://www.techsupplies.co.uk/epages/Store.sf/en_GB/?ObjectPath=/Shops/Store.TechSupplies/Products/RFA020. These nifty little units work really well at short range.
Lots to learn, much fun to be had; good kit to be constructed! Hope this helps.