Advanced Qualification · A-005 Transmitters, modulation and processing · A-005-009-011
How does the spread-spectrum technique of frequency hopping work?
- AIf interference is detected by the receiver, it will signal the transmitter to change frequency
- BIf interference is detected by the receiver, it will signal the transmitter to wait until the frequency is clear
- CA pseudo-random bit stream is used to shift the phase of an RF carrier very rapidly in a particular sequence
- DThe frequency of an RF carrier is changed very rapidly according to particular pseudo-random sequence
Correct answer: D — The frequency of an RF carrier is changed very rapidly according to particular pseudo-random sequence. From the official ISED question bank, verified word for word.
Why
Frequency hopping works by making the radio jump its carrier frequency many times per second following a secret, random-looking pattern known as a pseudo-random sequence. 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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