Basic Qualification · B-008 Interference and suppression · B-008-004-002
What are harmonic emissions?
- A Unwanted signals that are combined with a 60 Hz hum
- B Unwanted signals caused by mixing with a nearby transmitter
- C Signals which cause skip propagation occur
- D Unwanted signals at frequencies which are multiples of the fundamental (operating) frequency
Correct answer: D — Unwanted signals at frequencies which are multiples of the fundamental (operating) frequency. From the official ISED question bank, verified word for word.
Why
Harmonic emissions happen when a transmitter sends out extra, unwanted signals at frequencies that are exact multiples of your main operating frequency, such as double or triple the intended rate. The full explanation — and one for every question — is in Pro.
Practise this section
When things interfere: harmonics, overload, RFI to and from your station, filters, ferrites and how to fix the neighbour's TV.