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.
Pure natural gas is colourless and odourless. This means if there is a leak people will not be able to detect it until it builds up enough to become explosive. For this reason a chemical called Mercaptan is added to the gas to make is smell. Mercaptan is harmless, non-toxic and has a strong rotten egg smell.