Advanced Qualification · A-005 Transmitters, modulation and processing · A-005-009-010
Why are received spread-spectrum signals so resistant to interference?
- AIf interference is detected by the receiver, it will signal the transmitter to change frequencies
- BThe high power used by a spread-spectrum transmitter keeps its signal from being easily overpowered
- CSignals not using the spectrum-spreading algorithm are suppressed in the receiver
- DThe receiver is always equipped with special digital signal processor (DSP) interference filter
Correct answer: C — Signals not using the spectrum-spreading algorithm are suppressed in the receiver. From the official ISED question bank, verified word for word.
Why
Spread-spectrum signals resist interference because the receiver only reconstructs the intended message if it follows the exact same spreading pattern; any signal that does not use this specific algorithm appears as low-level background noise and gets suppressed. The full explanation — and one for every question — is in Pro.
Practise this section
Transmitters, modulation and processing is section A-005 of the Advanced exam: Transmitters, modulation and processing: AM, FM, SSB, keying, speech processing, and the numbers behind occupied bandwidth.
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