# New to RF and need help finding suitable modules

#### mrjbones

Joined Mar 26, 2011
3
Hi all,

I need a pair of modules (rx/tx) for a small personal project. The following are my constraints...

1) Range: Should be reliable outside in the open at 300 feet.
2) Transmitter must be small. Preferably small enough to fit in a key fob.
3) Receiver should also be small but there is a little more wiggle room.
4) I'd prefer the receiver had an integrated antenna. No room for a long one at any rate.
5) Multiple rx/tx pairs may need to operate in the same area. It doesn't have to be secure or anything; transmitting a 4 or 8 bit ID (set with dip switches on both the rx/tx, maybe) would probably suffice.
6) Other than #5, the data that needs to be transmitted is very simple. I need to send a single pulse on any one of three channels at a time. Or any equivalent that will work (e.g. 2 bits serially.)
7) I need to interface with a PICAXE 08M on the receiver side.
8) I don't care much about frequency except that I need to abide by US laws and need a short antenna.
9) I'll need to build a bunch of these eventually so the lower the cost, the better. Ideally, price for each module would be less than $10 (i.e. less than$20 for a rx/tx pair.)

Thanks for any recommendations, advice, pointers, or assistance of any kind that you can provide.

Kind regards,
-j

#### mrjbones

Joined Mar 26, 2011
3
No help for the newb?

#### bertus

Joined Apr 5, 2008
20,566
Hello,

Did you have a look at the xBee?
They seem to reach 100 feet indoor and 300 feet outdoors.
This PDF uses it in combination with a picaxe:
http://www.rev-ed.co.uk/docs/axe210.pdf

Bertus