Advanced Qualification · A-005 Transmitters, modulation and processing · A-005-004-010
Dans une transmission BLU en phonie, de combien de décibels la porteuse est-elle supprimée par rapport à la puissance crête de sortie?
- AAu moins 60 dB
- BAu moins 40 dB
- CPas plus de 20 dB
- DPas plus de 30 dB
Correct answer: B — Au moins 40 dB. Question tirée de la banque officielle d'ISDE.
Why
In a single-sideband phone transmission, the carrier is intentionally removed to save power and bandwidth, and regulations require it to be reduced by at least 40 decibels compared to the peak output. 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