Advanced Qualification · A-005 Transmitters, modulation and processing · A-005-005-008
Some types of deviation meters work on the principle of:
- Aa carrier null and multiplying the modulation frequency by the modulation index
- Bdetecting the frequencies in the sidebands
- Cthe amplitude of power in the sidebands
- Da carrier peak and dividing by the modulation index
Correct answer: A — a carrier null and multiplying the modulation frequency by the modulation index. From the official ISED question bank, verified word for word.
Why
Some deviation meters find the exact point where the main carrier signal disappears, known as a carrier null, and then calculate the frequency shift by multiplying the modulation frequency by the modulation index. 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.
Drill A-005 — free, no account