15 years ago, I worked on RF garage door openers and was amazed to find how poor the range was compared with the bench measured sensitivity of the receivers. I learned that the EM smog is so bad in cities that receivers never get anywhere near their noise floor. The many strong carriers desensitise your receiver by creating IMD products and the weak mush brings up the broadband noise floor.
Right now, my ethernet switch puts lines on my TV screen.
Roger Lascelles