Transmitter and Receiver-- Proximity

I want to build this type of a circuit. Does Sparkfun offer the components that would help me achieve this. it is for a science fair project. Any links or suggestions appreciated!

http://www.maximintegrated.com/app-note … vp/id/5099

It could also be a simpler set up of a transmitter and receiver pair. I could use some help my knowledge is limited! :?

I don’t think that SF sells anything that would be simpler or easier than the setup you linked to.

Perhaps you could explain the goal of your project a little more ? What are you trying to demonstrate ?

Yes. It is a science fair project. Our goal is to have a transmitter beep once it gets a certain distance from a receiver located on the underside of a car seat (inside a car). Originally we modified a dog containment fence to achieve our goal but now as we progress we want to try to make one ourselves.

I think you want the receiver to beep when it get’s a certain distance from the transmitter. Which is in the car and which is on the move ? Is the distance to be outside of the car’s interior ? How repeatable and accurate must the distance be ? Would it be good enough to have the alarm beep when the separation was anywhere between X feet and 2X feet or must it be more defined, like between X +/- 0.05X ?

The RF modules SF sells are made to transmit data from station A to station B. The receiver at B might have a received signal strength indicator (RSSI) and that might be used similarly to what was done in your link. But there’s other components needed to setup the modules that make it a lot harder than the simple beacon transmitter and “receiver” that was in your link.

I would also advise you that using RF signal strength as a measure of distance from the transmitter is generally a pretty imprecise thing. The signal strength is a function of number of things, a lot of which you can’t control. A dog fence works because it doesn’t matter if Fido gets a warning 1 foot away or 5 feet away, just so long as he does get the warning before he crosses the “fence”.