ARRL Technician Practice Exam

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Prepare for the ARRL Technician Exam. Study with flashcards and multiple choice questions, each question has hints and explanations. Get ready for your exam!

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What term is commonly used to describe the rapid fluttering sound sometimes heard from mobile stations that are moving while transmitting?

Picket fencing
Static noise
Interference reflection
Signal distortion

The correct answer is: Picket fencing

The term "picket fencing" is used to describe the phenomenon where a mobile station, while in motion, produces a rapid fluttering sound during transmission. This occurs due to the Doppler effect, where the frequency of the received signal varies as the mobile station moves towards or away from the receiving station. As the vehicle moves, the signal can fluctuate rapidly, creating a sound that resembles a fluttering or flickering pattern, akin to picket fences seen in a yard. This phenomenon is especially noticeable in VHF (Very High Frequency) and UHF (Ultra High Frequency) communications, where the effect is more pronounced due to the higher frequency involved. Recognizing this term is helpful for operators as it describes a common issue in mobile operations that can affect communication clarity and effectiveness.