Fm definition

Also known as frequency-shift keying (FSK). A signal modulation technique in which the frequency of the analog carrier sine wave is varied to distinguish between a 1 bit and a 0 bit. For example, FM is the sole technique used in low-speed, Hayes-compatible modems. When no bits are transmitted, the carrier is at a reference frequency of 1700 Hz. A unibit FM technique impresses one bit on each baud by shifting the carrier to 2200 Hz when transmitting a 1 bit, and to 1200 Hz when transmitting a 0 bit. At 2400 baud, therefore, the transmission rate is 2400 bps.The benefits of dibit transmission can be realized by defining four frequencies, with each sine wave or set of sine waves representing a 2-bit pattern (00, 01, 10, and 11).Thereby, at 2400 baud, the transmission rate is 4800 bps. Figure F-3 illustrates unibit frequency modulation, with the carrier waveform modulated to a relatively high frequency to represent a 1 bit and to a relatively low frequency to represent a 0 bit. FM often is used in conjunction with amplitude modulation (AM) and phase-shift keying (PSK). A variation on the FSK theme is Gaussian frequency-shift keying (GFSK), which is used in DECT and Bluetooth wireless networks. See also AM, analog, Bluetooth, carrier, DECT, GFSK, modulation, PSK, sine wave, and transmission rate.

Abbreviation for Fathom.

(chemistry) Symbol for fermium.

The ccTLD for Federated States of Micronesia as assigned by the IANA.