ARRL Technician Practice Exam

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Prepare for the ARRL Technician Exam. Access flashcards and multiple choice questions with detailed explanations. Get ready to become a certified amateur radio operator!

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Which of the following types of emission has the narrowest bandwidth?

The correct answer is: CW

The type of emission with the narrowest bandwidth is continuous wave (CW). CW is essentially a method of transmitting information by turning a radio wave on and off, which allows it to occupy a very slim frequency range. This characteristic results in a very narrow bandwidth compared to other types of modulation. For example, FM (frequency modulation) has a wider bandwidth due to the changing frequency of the carrier wave in relation to the amplitude of the input signal. AM (amplitude modulation) also has a wider bandwidth because it involves varying the amplitude of the carrier wave, resulting in the need for more frequency space to accommodate the sidebands. Single Sideband (SSB) is a form of AM that also reduces bandwidth by eliminating one of the sidebands and the carrier, but it still inherently requires a broader bandwidth than CW because of the way it modulates the signal. Therefore, CW stands out as the most bandwidth-efficient mode, making it the correct answer.