What is meant by the term “baseband” in radio communications?
The correct answer is B: The frequency range occupied by a message signal prior to modulation. What is meant by the term 'baseband' in radio communications is the frequency range occupied by a message signal prior to modulation. Baseband is the original signal before modulation. For amateur radio operators, this is important for modulation theory. Understanding this helps when working with modulation.
Exam Tip
Baseband in radio communications = frequency range occupied by message signal prior to modulation. Think 'B'aseband = 'B'efore modulation (message signal). Baseband is the original signal before modulation. Not lowest frequency band, not unmodulated bandwidth, not oscillator frequency - just message signal before modulation.
Memory Aid
"Baseband in radio communications = frequency range occupied by message signal prior to modulation. Think 'B'aseband = 'B'efore modulation. Baseband is the original signal before modulation. Important for modulation theory."
Real-World Application
The term 'baseband' in radio communications: It means the frequency range occupied by a message signal prior to modulation. For example, audio signals (300-3000 Hz) are baseband before being modulated onto an RF carrier. This is what baseband means - message signal before modulation.
Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. Lowest frequency band that transmitter/receiver covers isn't baseband - baseband is message signal before modulation. Lowest frequency band isn't baseband.
Option C: Incorrect. Unmodulated bandwidth of transmitted signal isn't baseband - baseband is message signal before modulation. Unmodulated bandwidth isn't baseband.
Option D: Incorrect. Basic oscillator frequency multiplied to increase deviation isn't baseband - baseband is message signal before modulation. Oscillator frequency isn't baseband.
题目解析
The correct answer is B: The frequency range occupied by a message signal prior to modulation. What is meant by the term 'baseband' in radio communications is the frequency range occupied by a message signal prior to modulation. Baseband is the original signal before modulation. For amateur radio operators, this is important for modulation theory. Understanding this helps when working with modulation.
考试技巧
Baseband in radio communications = frequency range occupied by message signal prior to modulation. Think 'B'aseband = 'B'efore modulation (message signal). Baseband is the original signal before modulation. Not lowest frequency band, not unmodulated bandwidth, not oscillator frequency - just message signal before modulation.
记忆口诀
Baseband in radio communications = frequency range occupied by message signal prior to modulation. Think 'B'aseband = 'B'efore modulation. Baseband is the original signal before modulation. Important for modulation theory.
实际应用示例
The term 'baseband' in radio communications: It means the frequency range occupied by a message signal prior to modulation. For example, audio signals (300-3000 Hz) are baseband before being modulated onto an RF carrier. This is what baseband means - message signal before modulation.
错误选项分析
Option A: Incorrect. Lowest frequency band that transmitter/receiver covers isn't baseband - baseband is message signal before modulation. Lowest frequency band isn't baseband. Option C: Incorrect. Unmodulated bandwidth of transmitted signal isn't baseband - baseband is message signal before modulation. Unmodulated bandwidth isn't baseband. Option D: Incorrect. Basic oscillator frequency multiplied to increase deviation isn't baseband - baseband is message signal before modulation. Oscillator frequency isn't baseband.
知识点
Term, Baseband, Radio communications, Frequency range, Message signal, Prior to modulation
Verified Content
Question from official FCC Extra Class question pool. Explanation reviewed by licensed amateur radio operators.