Siirtymäavainmodulaatio

Siirtymäavainmodulaatio, often translated as shift key modulation or more generally as frequency shift keying (FSK), is a digital modulation technique used to transmit digital data by varying the frequency of a carrier signal. In FSK, binary data is represented by discrete shifts in the carrier frequency. For instance, a '0' bit might be represented by one frequency, and a '1' bit by a different frequency. This change in frequency is detected at the receiving end to reconstruct the original digital signal.

The simplest form of FSK is binary FSK (BFSK), which uses two distinct frequencies. More advanced versions can utilize more than two frequencies to achieve higher data rates, a concept known as M-ary FSK, where M represents the number of possible frequencies. FSK is relatively simple to implement and is known for its robustness against noise and interference, making it suitable for applications where signal integrity is critical but high data rates are not the primary concern. It finds applications in various communication systems, including radio modems, barcode scanners, and some older telecommunications systems. The spectrum efficiency of FSK is generally lower compared to other digital modulation schemes like phase-shift keying (PSK) or quadrature amplitude modulation (QAM).