Bærebølge

Bærebølge is a high‑frequency electromagnetic wave that serves as the carrier for information in radio and telecommunications. It provides a stable reference signal that is modulated by a baseband message, allowing voice, data, or video to be transmitted over distance. The carrier itself typically has a single, well-defined frequency and is perceived by the receiver as the tone around which the modulated signal varies.

Information is encoded onto the carrier through modulation. In analog systems, amplitude modulation (AM) varies the carrier’s amplitude, while frequency modulation (FM) or phase modulation (PM) varies its frequency or phase. Digital communications use more complex schemes that modulate the carrier with symbols representing bits, such as QAM or PSK, enabling higher data rates within the same bandwidth. The choice of modulation affects the required bandwidth, robustness to noise, and spectral efficiency.

Generation and reception are based on oscillator-based processes. A transmitter creates the carrier with an electronic oscillator and then modulates it before upconverting to the target radio frequency for transmission via an antenna. A receiver uses a demodulator to recover the baseband signal by removing or detecting the carrier’s modulation, followed by amplification and decoding.

The carrier frequency determines the radio band and propagation characteristics, while the modulation determines data rate and spectral footprint. Bærebølge is central to both analog and digital radio systems and to the broader concept of converting information into a form suitable for transmission over space, cables, or optical links.