COFDM

COFDM is the modulation scheme underpinning DAB radio, DAB+, DVB-T digital television, and several mobile-TV standards. It splits the transmitted signal across many closely-spaced orthogonal subcarriers, spreading the information across frequency. Even if specific subcarriers are wiped out by multipath interference or fading: a frequent problem for mobile reception: the error-correction coding embedded in COFDM recovers the original data.

The engineering elegance of COFDM is why digital terrestrial broadcast works robustly in cars, buses, and trains. Analog FM fades, crackles, and distorts when a driver passes through a tunnel or under an overpass; COFDM simply blanks out momentarily and resumes with no audible artefacts. This resilience is the single biggest practical advantage of digital-terrestrial broadcast over analog.