Deep Dive: E4A01
The correct answer is A: Sampling rate of the analog-to-digital converter. Which of the following limits the highest frequency signal that can be accurately displayed on a digital oscilloscope is the sampling rate of the analog-to-digital converter. The sampling rate must be at least twice the signal frequency (Nyquist criterion). For amateur radio operators, this is important for test equipment. Understanding this helps when using oscilloscopes.
Why Other Answers Are Wrong
Option B: Incorrect. ADC reference frequency isn't the limiting factor - sampling rate is. Reference frequency isn't the limit. Option C: Incorrect. Q of the circuit isn't the limiting factor - sampling rate is. Circuit Q isn't the limit. Option D: Incorrect. Since B and C are not correct, 'all of the above' cannot be correct. Only sampling rate is the limit.
Exam Tip
Digital oscilloscope frequency limit = sampling rate of ADC. Think 'D'igital 'O'scilloscope = 'D'epends on 'O'versampling (sampling rate). The sampling rate must be at least twice the signal frequency (Nyquist criterion). Not reference frequency, not circuit Q - just sampling rate.
Memory Aid
Digital oscilloscope frequency limit = sampling rate of ADC. Think 'D'igital 'O'scilloscope = 'S'ampling 'R'ate. The sampling rate must be at least twice the signal frequency (Nyquist criterion). Important for test equipment.
Real-World Example
A digital oscilloscope: The highest frequency signal that can be accurately displayed is limited by the sampling rate of the analog-to-digital converter. According to the Nyquist criterion, the sampling rate must be at least twice the signal frequency. This is the limit - sampling rate of the ADC.
Source & Coverage
Question Pool: 2024-2028 Question Pool
Subelement: E4A
Reference: 2024-2028 Question Pool · E4 - Amateur Practices
Key Concepts
Verified Content
Question from the official FCC Extra Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the E4A topic.