What process combines two signals in a non-linear circuit to produce unwanted spurious outputs?
The correct answer is A: Intermodulation. The process that combines two signals in a non-linear circuit to produce unwanted spurious outputs is intermodulation. Intermodulation (IMD) occurs when signals mix in non-linear circuits, creating unwanted products. For amateur radio operators, this is a common source of interference. Understanding this helps when troubleshooting interference.
Exam Tip
Unwanted spurious outputs from non-linear mixing = intermodulation. Think 'I'ntermodulation = 'I'nterfering 'M'ixing 'D'istortion. Intermodulation occurs when signals mix in non-linear circuits, creating unwanted products. Not heterodyning (intentional), not detection, not rolloff - just intermodulation.
Memory Aid
"Unwanted spurious outputs from non-linear mixing = intermodulation. Think 'I'ntermodulation = 'I'nterfering 'M'ixing. Intermodulation occurs when signals mix in non-linear circuits, creating unwanted products. Common source of interference."
Real-World Application
Two strong signals enter a non-linear amplifier. Intermodulation occurs - the signals mix, producing unwanted spurious outputs (e.g., 2F1-F2, 2F2-F1). These spurious signals can interfere with other frequencies. Intermodulation is a common source of interference in non-linear circuits. This is why linearity is important.
Key Concepts
Why Other Options Are Wrong
Option B (Heterodyning): Incorrect. Heterodyning is intentional mixing in linear mixers, not unwanted spurious outputs from non-linear circuits - intermodulation is unwanted mixing. Heterodyning is intentional.
Option C (Detection): Incorrect. Detection is extracting modulation from a signal, not producing spurious outputs - intermodulation produces unwanted products. Detection is different.
Option D (Rolloff): Incorrect. Rolloff is filter attenuation rate, not spurious output production - intermodulation produces unwanted products. Rolloff is different.
题目解析
The correct answer is A: Intermodulation. The process that combines two signals in a non-linear circuit to produce unwanted spurious outputs is intermodulation. Intermodulation (IMD) occurs when signals mix in non-linear circuits, creating unwanted products. For amateur radio operators, this is a common source of interference. Understanding this helps when troubleshooting interference.
考试技巧
Unwanted spurious outputs from non-linear mixing = intermodulation. Think 'I'ntermodulation = 'I'nterfering 'M'ixing 'D'istortion. Intermodulation occurs when signals mix in non-linear circuits, creating unwanted products. Not heterodyning (intentional), not detection, not rolloff - just intermodulation.
记忆口诀
Unwanted spurious outputs from non-linear mixing = intermodulation. Think 'I'ntermodulation = 'I'nterfering 'M'ixing. Intermodulation occurs when signals mix in non-linear circuits, creating unwanted products. Common source of interference.
实际应用示例
Two strong signals enter a non-linear amplifier. Intermodulation occurs - the signals mix, producing unwanted spurious outputs (e.g., 2F1-F2, 2F2-F1). These spurious signals can interfere with other frequencies. Intermodulation is a common source of interference in non-linear circuits. This is why linearity is important.
错误选项分析
Option B (Heterodyning): Incorrect. Heterodyning is intentional mixing in linear mixers, not unwanted spurious outputs from non-linear circuits - intermodulation is unwanted mixing. Heterodyning is intentional. Option C (Detection): Incorrect. Detection is extracting modulation from a signal, not producing spurious outputs - intermodulation produces unwanted products. Detection is different. Option D (Rolloff): Incorrect. Rolloff is filter attenuation rate, not spurious output production - intermodulation produces unwanted products. Rolloff is different.
知识点
Intermodulation, Non-linear circuit, Spurious outputs, IMD
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.