Advanced Qualification · A-006 Receivers · A-006-002-005
The BFO is off-set slightly (500 - 1 500 Hz) from the incoming signal to the detector. This is required:
- A to provide additional amplification
- B to protect the incoming signal from interference
- C to beat with the incoming signal
- D to pass the signal without interruption
Correct answer: C — to beat with the incoming signal. From the official ISED question bank, verified word for word.
Why
The BFO, or Beat Frequency Oscillator, is tuned slightly off the incoming signal so the two frequencies mix inside the receiver. The full explanation — and one for every question — is in Pro.
Practise this section
Receivers: superheterodyne design, selectivity, sensitivity, images, AGC and noise.