Advanced Qualification · A-005 Transmitters, modulation and processing · A-005-005-004
Quel est le facteur d'excursion ("deviation ratio") d'un émetteur FM en phonie ayant une excursion maximale de fréquence de plus ou moins 7,5 kHz et dont la fréquence modulante maximale est de 3,5 kHz?
- A47
- B0,214
- C2,14
- D0,47
Correct answer: C — 2,14. Question tirée de la banque officielle d'ISDE.
Why
The deviation ratio is found by dividing the maximum frequency swing of 7.5 kHz by the highest modulation rate of 3.5 kHz, which equals roughly 2.14. 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