Radio waves travel 186,000 miles in one second (at the speed of light).
Analog radio signals cause characteristic changes, or modulations, in the radio waves that carry them: amplitude modulation (AM) and frequency modulation (FM). An old technology compared to newer digital signals such as satellite and high definition radio, differences that distinguish analog radio from digital radio include signal characteristics, sound clarity and cost.
Type of Signal Transmission
Carrier waves -- invisible forms of electricity and magnetism that travel wirelessly from radio broadcasting stations to radio receivers -- transmit AM, FM and digital HD radio programs. Digital signals transmit via pulses or digits of binary code, a language based on the numbers 0 and 1, before decoding.
Clarity of Sound
FM analog radio signals encounter interference when large objects such as mountains or buildings enter the intended path of travel, and cannot bend, unlike AM analog signals. An interrupted analog signal results in a crackling, unclear radio station. Digital radio signals generally don't experience interference errors, although bad weather can severely affect satellite stations.
Cost
Most perks have a catch. Satellite radio plays very few commercials, but there's a subscription fee and you must buy a satellite specific receiver. While free, traditional AM/FM radio and HD radio include commercial advertisements. To hear HD radio, you need a specific HD receiver. Digital HD receivers can play both analog and HD radio stations, but traditional analog receivers can stream only AM/FM stations.
Tags: analog radio, radio signals, radio include, specific receiver