FMkringkasting

FMkringkasting is a method of radio broadcasting that uses frequency modulation to transmit audio signals over the VHF radio spectrum. In contrast to amplitude modulation, FMkringkasting encodes the information in variations of the carrier frequency, which yields higher fidelity and resistance to amplitude noise. A typical FMkringkasting broadcast uses a channel width of about 200 kHz and operates in the VHF band from about 87.5 to 108.0 MHz in many regions, with exact frequencies and spacing set by regulators.

FMkringkasting was developed in the early 20th century, with significant contributions from American engineer Edwin Howard Armstrong in the 1930s and 1940s. It began to be adopted for music broadcasting in the 1950s and 1960s, eventually becoming the standard for high‑quality radio in many countries. The technology coexists with AM broadcasting, and in some markets with digital radio.

Stereo FMkringkasting introduces left and right channels by encoding a double sideband suppressed subcarrier at 38 kHz, synchronized by a 19 kHz pilot tone. The baseband audio is typically limited to about 15 kHz; RDS data can be transmitted at 57 kHz. Transmitters vary widely in power, from a few watts for local stations to tens or hundreds of kilowatts for larger coverage. Antenna height and terrain determine practical range.

FMkringkasting is generally line‑of‑sight; range depends on transmitter height and terrain. It offers high fidelity and noise immunity but requires more spectrum per station and can suffer from multipath distortion in built‑up areas.

Regulation of FMkringkasting is typically handled by national authorities that allocate bands, issue licenses, and set emission limits to manage interference. In recent decades digital radio options have emerged alongside FMkringkasting, but FM remains widely used for music and public‑service broadcasting.