Advanced Qualification · A-005 Transmitters, modulation and processing · A-005-005-001
In an FM phone signal having a maximum frequency deviation of 3000 Hz either side of the carrier frequency, what is the modulation index, when the modulating frequency is 1000 Hz?
- A0.3
- B3000
- C1000
- D3
Correct answer: D — 3. From the official ISED question bank, verified word for word.
Why
The modulation index is simply the ratio of how far the frequency swings to how fast it swings. 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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