What term specifies a filter’s maximum ability to reject signals outside its passband?
The correct answer is D: Ultimate rejection. The term that specifies a filter's maximum ability to reject signals outside its passband is ultimate rejection. Ultimate rejection measures how well a filter blocks out-of-band signals. For amateur radio operators, this is important for filter performance. Understanding this helps when evaluating filters.
Exam Tip
Filter stopband rejection = ultimate rejection. Think 'U'ltimate 'R'ejection = 'U'ltimate 'R'emoval of out-of-band signals. Ultimate rejection measures how well filter blocks out-of-band signals. Not notch depth, not rolloff (slope), not insertion loss (passband) - just ultimate rejection.
Memory Aid
"Filter stopband rejection = ultimate rejection. Think 'U'ltimate 'R'ejection = 'U'ltimate 'R'emoval. Ultimate rejection measures how well filter blocks out-of-band signals. Key filter performance parameter."
Real-World Application
A filter has 60 dB ultimate rejection. This means out-of-band signals are attenuated by at least 60 dB. Ultimate rejection measures the filter's maximum ability to reject signals outside its passband. Higher ultimate rejection means better out-of-band rejection. This is a key filter performance parameter.
Key Concepts
Why Other Options Are Wrong
Option A (Notch depth): Incorrect. Notch depth is for notch filters (rejection at a specific frequency), not general stopband rejection. Notch depth is different.
Option B (Rolloff): Incorrect. Rolloff is the rate of attenuation (dB per octave), not the maximum rejection. Rolloff is the slope, not the ultimate value.
Option C (Insertion loss): Incorrect. Insertion loss is passband attenuation, not stopband rejection. Insertion loss is for in-band signals, not out-of-band.
题目解析
The correct answer is D: Ultimate rejection. The term that specifies a filter's maximum ability to reject signals outside its passband is ultimate rejection. Ultimate rejection measures how well a filter blocks out-of-band signals. For amateur radio operators, this is important for filter performance. Understanding this helps when evaluating filters.
考试技巧
Filter stopband rejection = ultimate rejection. Think 'U'ltimate 'R'ejection = 'U'ltimate 'R'emoval of out-of-band signals. Ultimate rejection measures how well filter blocks out-of-band signals. Not notch depth, not rolloff (slope), not insertion loss (passband) - just ultimate rejection.
记忆口诀
Filter stopband rejection = ultimate rejection. Think 'U'ltimate 'R'ejection = 'U'ltimate 'R'emoval. Ultimate rejection measures how well filter blocks out-of-band signals. Key filter performance parameter.
实际应用示例
A filter has 60 dB ultimate rejection. This means out-of-band signals are attenuated by at least 60 dB. Ultimate rejection measures the filter's maximum ability to reject signals outside its passband. Higher ultimate rejection means better out-of-band rejection. This is a key filter performance parameter.
错误选项分析
Option A (Notch depth): Incorrect. Notch depth is for notch filters (rejection at a specific frequency), not general stopband rejection. Notch depth is different. Option B (Rolloff): Incorrect. Rolloff is the rate of attenuation (dB per octave), not the maximum rejection. Rolloff is the slope, not the ultimate value. Option C (Insertion loss): Incorrect. Insertion loss is passband attenuation, not stopband rejection. Insertion loss is for in-band signals, not out-of-band.
知识点
Filter rejection, Ultimate rejection, Stopband, Filter performance
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.