Question
What is the purpose of using a prescaler with a frequency counter?
Answer Options
- A) Amplify low-level signals for more accurate counting
- B) Multiply a higher frequency signal so a low-frequency counter can display the operating frequency
- C) Prevent oscillation in a low-frequency counter circuit
- D) Reduce the signal frequency to within the counter’s operating range
Correct Answer: D
Explanation
A frequency counter’s ability to measure extremely high frequencies is often limited by the maximum speed of its internal digital logic circuits. While an operator may need to measure a signal in the gigahertz range (e.g., in a microwave circuit), the counter’s internal counting stage may only be rated for a few hundred megahertz.
The purpose of a prescaler is to act as a preliminary frequency divider. It takes the very high input frequency and uses high-speed divider circuits (often specialized ICs) to reduce the signal frequency to within the counter’s operating range. For example, a \div 10 prescaler allows a 500 MHz counter to measure signals up to 5 GHz. The counter then applies the multiplication factor to the displayed count to show the true input frequency.
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