Question
Which types of modulation are used for amateur television DVB-T signals?
Answer Options
- A) FM and FSK
- B) QAM and QPSK
- C) AM and OOK
- D) All these choices are correct
Correct Answer: B
Explanation
Digital Video Broadcasting - Terrestrial (DVB-T) is the digital standard often adopted by amateur television (ATV) operators because it is spectrally efficient and designed for robust reception. Unlike older analog TV, DVB-T relies entirely on digital modulation schemes that efficiently pack data into the RF carrier.
The modulation types used for DVB-T signals are complex phase and amplitude schemes, specifically QAM (Quadrature Amplitude Modulation) and QPSK (Quadrature Phase-Shift Keying). QAM varies both the phase and amplitude of the carrier to transmit multiple bits per symbol, while QPSK varies only the phase. These high-order digital modulation schemes maximize the amount of video and audio data that can be carried within the limited amateur frequency allocation.
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