RF modules with encoding?

Hi, all:-

I'm looking for a small, and low power, pair of RF modules (send and receive, only one-way communication) that could be used to send a couple of messages (specifically, "ON" and "OFF" commands) with encoding so that stray RF won't cause it to malfunction (the consquences are expensive, and possibly even dangerous). Maybe something in the ISM band. If the transmitter works off a key fob with a button cell, all the better. It would be nice if there was no local oscillator or other leakage of signals from the receiver. There will probably be a number of receivers and a single transmitter. Range is not an issue (a few dozen meters is fine).

It doesn't have to be really secure against deliberate attempts to spoof the code, just against accidental actuation.

Any suggestions?

Best regards, Spehro Pefhany

Check out the X-10 key fobs. Really cheap. Their receivers are IMHO not very good so you'll have to roll your own.

Spehro Pefhany wrote in news: snipped-for-privacy@4ax.com:

I have heard of some (like Holtek perhaps), although they do no more than gate the carrier on and off based on the logic you feed them, and present a signal at the receiver based on the status of that logic signal entering the trasnmitter. Error correction and that would be don by the logic you supply on either side. That said, you could use simple remote control transmitter chips or a micro in the trasnmitter, and a micro to decode, if no direct decoder IC is available..

Thanks, Tony, they look decent.

Best regards,

Best regards, Spehro Pefhany

innews: snipped-for-privacy@4ax.com:

I second the recommendation for Linx Technologies. You can get Holtek-encoded keyfob transmitters with 1 to 5 buttons off the shelf and pair them with their KH2 receiver/decoder modules for very cheap and Digi-Key stocks them. Be aware, though, that Linx requires you purchase one of their evaluation kits before they will sell to you direct anything not already FCC approved (ie - you can buy the keyfobs but not the matching receivers without first buying a stupid ev kit).

-Jeff

Don't you have to stand back farther than that? Or is the operator expendable...

It's almost the reverse situation of what you are thinking...