Enimmäistaajuuspoikkeama

Enimmäistaajuuspoikkeama, often translated as maximum frequency deviation, is a key parameter in frequency modulation (FM) radio broadcasting. It specifies the maximum extent to which the carrier frequency of an FM signal can deviate from its center frequency. This deviation is directly proportional to the amplitude of the modulating audio signal.

In FM broadcasting, the maximum frequency deviation is standardized to ensure consistent audio quality and efficient use of the allocated bandwidth. For the FM broadcast band in most of the world, this value is typically set at 75 kilohertz (kHz). This means the carrier frequency can swing up to 75 kHz above or below its assigned center frequency. This deviation is what carries the audio information. A stronger audio signal causes a larger frequency deviation, while a weaker signal causes a smaller deviation.

The concept of maximum frequency deviation is crucial for receiver design, as it determines the capture range and selectivity of the receiver. It also plays a role in spectrum management, as the total bandwidth occupied by an FM signal is related to its maximum frequency deviation and the highest modulating audio frequency. The Carson's rule is often used to estimate the bandwidth of an FM signal, which is approximately twice the sum of the maximum frequency deviation and the highest modulating audio frequency.