Basic Qualification · B-008 Interference and suppression · B-008-005-005
Listening to shortwave on a low-cost software defined receiver (SDR), you hear several stations known to operate on much higher frequencies. What type of filter could help?
- A Band-pass
- B Band-reject
- C Low-pass
- D High-pass
Correct answer: C — Low-pass. From the official ISED question bank, verified word for word.
Why
A low-pass filter allows signals below a certain frequency to pass while blocking those above it. 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.