RF remotes generally work this way: The originating signal is sent from the remote as RF (radio frequency.) In the case of the MX-950 in my theater that's 418MHz, a very stable and reliable frequency band.
By nature, propane is clear and contains no scent at all. For safety purposes propane. companies add a substance known as ethyl-mercaptan to the propane fuel. Ethyl-. mercaptan has a strong rotten egg, or skunk-like scent, which allows the consumer to. smell it in the case of a leak.
Hard to describe the smell -- a little like propane, but also a hint of garbage smell. We do have propane gas, but the area where it smells we shut off that line and we still get the smell. We have a 13-year-old house that has been waterproofed. We have treated the basement with an ozone generator, so we don't think it is mold.