It would be easy to disable the power to the radio completely, but it would take a modifciation to all existing radios. Granted the mod would be easy physically, but probably not mentally. People are a little apprenhensive to let you cut into their radios.

I was trying to make a first run attempt at this and I think it would see resistance if it was too different from the existing way.
My idea of the card was to try to replicate the clothespin, I think later versions by smarter folks than me will ultimately lead to more sophisticated units being built.

This is hopefully friendly enough that a lot of people would consider trying it. Considering I want to change an established way of doing something, thats often enough task on it's own. I also wanted to keep it as cheap as possible. Of course, I think it should be madatory at all fields.

I already bought some old traffic lights to use as the display if somebody wants to try a permanent installation. Traffic lights seem like a natural to me since we all know them as information signs anyway, plus they are weatherproof.

I really appreciate your input on this.

Scott