ARRL Technician Practice Exam

What is the name of a circuit that generates a signal of a desired frequency?

1. Modulator

2. Demodulator

3. Oscillator

4. Amplifier

The correct answer is: Oscillator

An oscillator is a circuit designed specifically to generate a signal at a desired frequency. It achieves this by converting direct current (DC) energy into an alternating current (AC) signal, which oscillates between positive and negative values. Oscillators can produce various waveforms, including sine, square, and triangular waves, depending on the design and components used. In communication systems, oscillators play a crucial role in generating carrier waves for modulation, enabling the transmission and reception of information over radio frequencies. Their precise frequency generation is vital for ensuring effective communication. In contrast, other devices like modulators and demodulators serve different purposes. Modulators combine information signals with carrier waves, while demodulators extract information from modulated signals. Amplifiers, on the other hand, are used to increase the power of a signal but do not generate frequencies on their own. Thus, the oscillator is distinct for its primary function of creating signals at specified frequencies.