What is the difference between an analog & a digital radio signal?

Written by bekah snyder
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What is the difference between an analog & a digital radio signal?
Radio waves travel 186,000 miles in one second (at the speed of light). (Radio image by Francesca from Fotolia.com)

Analogue 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 analogue 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 analogue radio signals encounter interference when large objects such as mountains or buildings enter the intended path of travel, and cannot bend, unlike AM analogue signals. An interrupted analogue 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.


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 analogue and HD radio stations, but traditional analogue receivers can stream only AM/FM stations.

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