Things always seem to get "too complicated" as soon as one asks about RF links.

What about a simple half-duplex link to take the place of a cable? Let's say we want to switch the light in the garage on/off without using a cable. We have a box in the garage and we have a box in the house. We want to send a signal to the box in the garage that contains enough information so the box in the garage will know what we want. The box in the house, 10 meters away, gets its instructions in a predetermined (not relevant here) way, and we want to send a distinct signal to the box in the garage, sitting inside, on the window ledge, within line-of-sight of the corresponding box in the house telling it to turn on the lights, which it is able to do by means not relevant to this discussion. We'd like this to be moderately robust, so that the neighbor's car or furnace don't cause the lights to come on or shut off, and we'd like not to set off the neighbors' alarms, or open their garage doors, or ours.

We don't need a costly and complicated protocol (e.g. zigbee) for this, do we? It's just a signal to turn on/off the lights.

What does one have to buy? How does one use it? what are the limits on information bandwidth, on range, etc? What does it cost, in units, in hundreds, and at 1k units per week? HOw long does it take to get 'em? ... (you get the picture)

We've seen little <$5/unit in unit quantity, transmitters and receivers, as well as transceivers, mentioned. Are they adequate? What should one watch out for?

I've seen several threads here that wind up saying, Buy this, or that..." but never go into implementation details and never compare cost, reliability, capabilities, etc.

Surely someone knows enough about this to "spell it out."

I'd like very much to know whether there's a low-cost way to do this sort of thing at the most basic level that actually works.

Experience has taught me that the people who sell this sort of stuff either (a) don't speak English well enough to describe their products or (b) are not well-enough-versed to answer questions.

In my case, I'd want to tell the remote box, "It's me, so you should listen ... Here's the code ... Did you understand that?" and get an acknowledgment back, since I can't see the garage light from the house.

RE