Basic Qualification · B-003 Station assembly, practice and safety · B-003-005-008
In an SSB/CW receiver, what is the purpose of the signal produced by the beat frequency oscillator (BFO)?
- A It is mixed with the incoming signal to produce the intermediate frequency
- B It drives the automatic gain control circuit to maintain a constant audio level
- C It is fed to the receiver input to provide band edge markers
- D It is mixed with the IF to recover the transmitted modulation
Correct answer: D — It is mixed with the IF to recover the transmitted modulation. From the official ISED question bank, verified word for word.
Why
In single-sideband and Morse code reception, the incoming radio signal lacks the carrier wave needed to create audible sound. The full explanation — and one for every question — is in Pro.
Practise this section
Building a station safely: power supplies, grounding, RF exposure, lightning, feedline routing, and what a transmitter, receiver and transceiver actually do.