Extra exam question E4E01
Subelement E4, AMATEUR PRACTICES· Group E4E
What problem can occur when using an automatic notch filter (ANF) to remove interfering carriers while receiving CW signals?
- A.Removal of the CW signal as well as the interfering carrier (correct answer)
- B.Any nearby signal passing through the DSP system will overwhelm the desired signal
- C.Excessive ringing
- D.All these choices are correct
WhyAn automatic notch filter used to remove interfering carriers while receiving CW can end up removing the CW signal itself. An automatic notch filter tuned to remove an interfering carrier can end up removing a CW signal too, since to the DSP algorithm a steady CW tone looks essentially identical to the kind of narrow, continuous carrier the filter is designed to notch out, answer A. Nearby signals overwhelming the desired one and excessive ringing are different, separate DSP-related issues, not what specifically happens when an ANF misidentifies a CW signal as an interfering carrier.
Published 2026-08-28 · Last updated 2026-08-28 · Question text is verbatim from the 2024-2028 NCVEC Element 4 pool (public domain); the explanation above is original writing, see our methodology.
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