How is a frequency counter primarily used?

A frequency counter is primarily used to measure the time between events, specifically to determine the frequency of an incoming signal. It achieves this by counting the number of cycles of the signal within a given time frame, which allows for accurate frequency measurements expressed in hertz (Hz). This capability is essential in various applications, such as telecommunications and electronic testing, where knowing the frequency of signals is critical for system functionality and reliability.

In contrast, the other options highlight different functions that do not align with the primary purpose of a frequency counter. Measuring voltage levels involves using a voltmeter, calibrating instruments typically requires a calibration standard or signal generator, and increasing signal strength pertains to the functions of amplifiers or signal boosters. Consequently, the use of a frequency counter distinctly focuses on quantifying the frequency and timing aspects of signals rather than these other measurement or enhancement functions.