For the purposes of this Chapter, “interference” shall mean any electrostatic or electromagnetic radiation of such magnitude that it will interfere with the reception by radio or television receiver of a broadcast signal from any radio or television station or any radio telephone transmitter when such broadcast signal is of local normal field strength. Radio or television receivers shall be of good engineering design, and in good operating condition, in establishing whether or not “interference” exists. This Chapter shall not be construed as regulating any device, appliance, equipment or apparatus used in interstate commerce in any case where such device, appliance, equipment or apparatus is licensed by the federal government.