Question
What is meant by the term “baseband” in radio communications?
Answer Options
- A) The lowest frequency band that the transmitter or receiver covers
- B) The frequency range occupied by a message signal prior to modulation
- C) The unmodulated bandwidth of the transmitted signal
- D) The basic oscillator frequency in an FM transmitter that is multiplied to increase the deviation and carrier frequency
Correct Answer: B
Explanation
In radio communications, the term baseband refers to the original, unmodulated information signal. This signal is the intelligence (voice, music, or digital data) that is to be transmitted and is always at a frequency lower than the radio frequency (\text{RF}) carrier wave.
Baseband is defined as the frequency range occupied by a message signal prior to modulation. For voice communication, the baseband is the audio frequency range (typically 300 \text{ Hz} to 3000 \text{ Hz}). For digital communication, it is the range occupied by the digital pulses or tones. This signal must be mixed or modulated onto an \text{RF} carrier for transmission over the air.
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