Quote:
Originally Posted by Astrodetect
Esteban I wanted to ask you what is the difference between off resonance and BFO?
Thanks
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Hi Astrodetect,
BFO and Off-resonance detectors are closely related, as they both rely on a metal target causing the TX oscillator to shift in frequency. In the BFO the TX signal is mixed with the output from a second internal oscillator (known as the local oscillator) to produce a beat frequency in the audio range. When the TX frequency changes, the audo note also changes. However, in the Off-resonance detector, the TX output is fed into a tuned circuit that is tuned off-resonance. The output of this circuit gives an amplitude change which can be used to trigger an audio output or a meter. So the only "audible" difference is that the BFO has a constant threshold tone that changes in frequency, whereas the Off-resonance detector can be silent search and only beeps when a certain threshold is reached. They both have about the same sensitivity to metal targets.