Which of the following can cause radio frequency interference?
The correct answer is D: All these choices are correct. Fundamental overload, harmonics, and spurious emissions can all cause radio frequency interference (RFI). Fundamental overload occurs when a strong signal overloads a receiver's front-end. Harmonics are integer multiples of the fundamental frequency (2nd harmonic = 2×, 3rd harmonic = 3×, etc.) that can interfere with other services. Spurious emissions are unwanted signals at frequencies other than the intended frequency, including harmonics, intermodulation products, and parasitic oscillations. For amateur radio operators, understanding all sources of interference is essential for legal operation and good neighbor relations. Proper station setup, filtering, and operation help minimize interference.
Exam Tip
All three cause interference: fundamental overload, harmonics, and spurious emissions. When you see 'all of the above' and all options are correct, that's usually the answer. All are valid sources of RFI.
Memory Aid
"All three cause RFI: Fundamental overload, Harmonics, Spurious emissions. Think 'A'll 'H'armful 'S'ignals cause interference. All are valid sources of RFI."
Real-World Application
Your 2-meter transmission might cause interference in three ways: (1) Fundamental overload - your 146 MHz signal overloads a nearby receiver, (2) Harmonics - your 2nd harmonic at 292 MHz interferes with UHF services, (3) Spurious emissions - unwanted signals from your transmitter interfere with other frequencies. Proper filtering, good station setup, and correct operation minimize all three types of interference.
Key Concepts
Why Other Options Are Wrong
Option A (Fundamental overload): While correct, this is incomplete. Harmonics and spurious emissions also cause interference, so the complete answer includes all three.
Option B (Harmonics): While correct, this is incomplete. Fundamental overload and spurious emissions also cause interference.
Option C (Spurious emissions): While correct, this is incomplete. Fundamental overload and harmonics also cause interference.
题目解析
The correct answer is D: All these choices are correct. Fundamental overload, harmonics, and spurious emissions can all cause radio frequency interference (RFI). Fundamental overload occurs when a strong signal overloads a receiver's front-end. Harmonics are integer multiples of the fundamental frequency (2nd harmonic = 2×, 3rd harmonic = 3×, etc.) that can interfere with other services. Spurious emissions are unwanted signals at frequencies other than the intended frequency, including harmonics, intermodulation products, and parasitic oscillations. For amateur radio operators, understanding all sources of interference is essential for legal operation and good neighbor relations. Proper station setup, filtering, and operation help minimize interference.
考试技巧
All three cause interference: fundamental overload, harmonics, and spurious emissions. When you see 'all of the above' and all options are correct, that's usually the answer. All are valid sources of RFI.
记忆口诀
All three cause RFI: Fundamental overload, Harmonics, Spurious emissions. Think 'A'll 'H'armful 'S'ignals cause interference. All are valid sources of RFI.
实际应用示例
Your 2-meter transmission might cause interference in three ways: (1) Fundamental overload - your 146 MHz signal overloads a nearby receiver, (2) Harmonics - your 2nd harmonic at 292 MHz interferes with UHF services, (3) Spurious emissions - unwanted signals from your transmitter interfere with other frequencies. Proper filtering, good station setup, and correct operation minimize all three types of interference.
错误选项分析
Option A (Fundamental overload): While correct, this is incomplete. Harmonics and spurious emissions also cause interference, so the complete answer includes all three. Option B (Harmonics): While correct, this is incomplete. Fundamental overload and spurious emissions also cause interference. Option C (Spurious emissions): While correct, this is incomplete. Fundamental overload and harmonics also cause interference.
知识点
RF interference, Fundamental overload, Harmonics, Spurious emissions
Verified Content
Question from official FCC Technician Class question pool. Explanation reviewed by licensed amateur radio operators.