Deep Dive: E4C03
The correct answer is C: Capture effect. What is the term for the suppression in an FM receiver of one signal by another stronger signal on the same frequency is capture effect. FM receivers capture the stronger signal and suppress the weaker one. For amateur radio operators, this is important for FM operation. Understanding this helps when operating FM.
Why Other Answers Are Wrong
Option A (Desensitization): Incorrect. Desensitization is reduction in receiver sensitivity, not suppression of weaker signal - capture effect is suppression. Desensitization isn't the term. Option B (Cross-modulation interference): Incorrect. Cross-modulation is modulation transfer, not suppression of weaker signal - capture effect is suppression. Cross-modulation isn't the term. Option D (Frequency discrimination): Incorrect. Frequency discrimination isn't the term - capture effect is suppression of weaker signal. Frequency discrimination isn't the term.
Exam Tip
FM suppression of weaker signal = capture effect. Think 'C'apture 'E'ffect = 'C'aptures 'E'stronger signal. FM receivers capture the stronger signal and suppress the weaker one. Not desensitization, not cross-modulation, not frequency discrimination - just capture effect.
Memory Aid
FM suppression of weaker signal = capture effect. Think 'C'apture 'E'ffect = 'S'tronger 'S'ignal wins. FM receivers capture the stronger signal and suppress the weaker one. Important for FM operation.
Real-World Example
In an FM receiver: When two signals are on the same frequency, the stronger signal suppresses (captures) the weaker one. This is called the capture effect. The receiver locks onto the stronger signal and ignores the weaker one. This is the term - capture effect.
Source & Coverage
Question Pool: 2024-2028 Question Pool
Subelement: E4C
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 E4C topic.