Single-sideband modulation
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In radio communications, single-sideband modulation or single-sideband suppressed-carrier modulation is a type of signal modulation used to transmit information, such as an audio signal, by radio wave
A Collins KWM-1, an early Amateur Radio transceiver that featured SSB voice capability
Beat frequency oscillator
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In a radio receiver, a beat frequency oscillator or BFO is a dedicated oscillator used to create an audio frequency signal from Morse code radiotelegraphy transmissions to make them audible. The signa
Single-sideband modulation
…sideband must be frequency-shifted down to its original range of baseband frequencies, by using a product detector which mixes it with the output of a beat frequency oscillator (BFO). In other words, it is just another stage of heterodyning. For this to work, the BFO frequency must be exactly adjusted. If the BFO frequency is…
455 kHz BFO unit for SSB reception
Separate BFO oscillators were manufactured for receivers that didn't have them; a Rohde und Schwarz STI4032 from 1944.
One of the first crude examples of a BFO, the Goldschmidt tone wheel. Before vacuum tube oscillators were invented, the first CW receivers used a wheel with electrical contacts around its rim, spun at a high speed by a motor, to interrupt a current to create a radio frequency signal to beat with the incoming radio signal. This example, at the Tuckerton transatlantic receiving station in New Jersey in 1917, created a 40 kHz signal.