Beat-frequency Oscillator is an oscillator used to set up audible beat frequencies with an incoming received signal and installed in the intermediate-frequency (IF) stages of a superheterodyne communications receiver. For single-sideband (SSB) reception, the BFO is set at the frequency of the received suppressed carrier. In continuous-wave (CW) Morse code reception, the BFO is set at a frequency that differs from that of the incoming signal by about 400 to 1000 Hz. The resulting tone has an audio frequency equal to the difference between the BFO frequency and the received signal carrier frequency. For reception of frequency-shift keyed (FSK) signals, the BFO is set to such a frequency that the resulting audio beat notes are appropriate for the mark and space inputs of a terminal unit or modem. Abbreviation, BFO.
See also, Beat frequency, Tickler Oscillator, Feedback Oscillator