Advanced Qualification · A-005 Transmitters, modulation and processing · A-005-006-005
What type of circuit varies the tuning of an amplifier tank circuit to produce FM signals?
- AA balanced modulator
- BA double balanced mixer
- CAn audio modulator
- DA phase modulator
Correct answer: D — A phase modulator. From the official ISED question bank, verified word for word.
Why
A phase modulator creates frequency modulation by shifting the phase of the carrier wave in step with the audio signal, which effectively changes the frequency over time. 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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