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.
In their natural state, LPG (Propane and Butane) and Natural Gas (Methane) are all odourless gases. The distinctive smell that people associate with these gases is actually added to them as a safety measure. For many decades, the gaseous fuels industry has added odourants to LPG and Natural Gas so that people can detect gas leaks with nothing more than their noses.