Which of the following is a measure of the quality of an analog-to-digital converter?
The correct answer is A: Total harmonic distortion. Total harmonic distortion (THD) is a measure of the quality of an analog-to-digital converter. THD measures how much the ADC's output differs from a perfect representation of the input, expressed as distortion products.
THD is the ratio of the sum of all harmonic distortion components to the fundamental signal. Lower THD means better ADC quality - the converter produces less distortion. THD is typically expressed as a percentage or in decibels. High-quality ADCs have very low THD (less than 0.01% or -80 dB). THD is an important specification because it tells you how accurately the ADC represents the input signal without adding unwanted harmonics.
Exam Tip
ADC quality measure = Total harmonic distortion. Remember: Total harmonic distortion (THD) is a key measure of ADC quality. Lower THD means better, more accurate conversion.
Memory Aid
"**A**DC **Q**uality = **T**otal **H**armonic **D**istortion (think 'AQ = THD')"
Real-World Application
You're evaluating ADCs for your SDR project. One ADC has 0.01% THD, while another has 0.1% THD. The first ADC is higher quality - it produces less distortion and more accurately represents the input signal. THD tells you how much the ADC's output deviates from a perfect representation due to harmonic distortion.
FCC Part 97.3Key Concepts
Why Other Options Are Wrong
Option B: Incorrect. Peak envelope power is a transmitter specification, not an ADC quality measure. It describes maximum power output, not conversion quality.
Option C: Incorrect. Reciprocal mixing is a receiver problem where local oscillator noise mixes with strong signals, not an ADC quality measure.
Option D: Incorrect. Power factor is an AC power system specification, not an ADC quality measure.
题目解析
The correct answer is A: Total harmonic distortion. Total harmonic distortion (THD) is a measure of the quality of an analog-to-digital converter. THD measures how much the ADC's output differs from a perfect representation of the input, expressed as distortion products. THD is the ratio of the sum of all harmonic distortion components to the fundamental signal. Lower THD means better ADC quality - the converter produces less distortion. THD is typically expressed as a percentage or in decibels. High-quality ADCs have very low THD (less than 0.01% or -80 dB). THD is an important specification because it tells you how accurately the ADC represents the input signal without adding unwanted harmonics.
考试技巧
ADC quality measure = Total harmonic distortion. Remember: Total harmonic distortion (THD) is a key measure of ADC quality. Lower THD means better, more accurate conversion.
记忆口诀
**A**DC **Q**uality = **T**otal **H**armonic **D**istortion (think 'AQ = THD')
实际应用示例
You're evaluating ADCs for your SDR project. One ADC has 0.01% THD, while another has 0.1% THD. The first ADC is higher quality - it produces less distortion and more accurately represents the input signal. THD tells you how much the ADC's output deviates from a perfect representation due to harmonic distortion.
错误选项分析
Option B: Incorrect. Peak envelope power is a transmitter specification, not an ADC quality measure. It describes maximum power output, not conversion quality. Option C: Incorrect. Reciprocal mixing is a receiver problem where local oscillator noise mixes with strong signals, not an ADC quality measure. Option D: Incorrect. Power factor is an AC power system specification, not an ADC quality measure.
知识点
Total harmonic distortion, THD, ADC quality, Distortion measurement
Verified Content
Question from official FCC Extra Class question pool. Explanation reviewed by licensed amateur radio operators.