Updated: Dec 9, 2025 | Source: 2024-2028 Question Pool | Topic: E4D
E4D06E4D

What is the term for the reduction in receiver sensitivity caused by a strong signal near the received frequency?

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Deep Dive: E4D06

The correct answer is C: Desensitization. What is the term for the reduction in receiver sensitivity caused by a strong signal near the received frequency is desensitization. Strong nearby signals reduce receiver sensitivity. For amateur radio operators, this is important for receiver performance. Understanding this helps when troubleshooting receivers.

Why Other Answers Are Wrong

Option A (Reciprocal mixing): Incorrect. Reciprocal mixing is LO phase noise mixing with adjacent signals, not reduction in sensitivity - desensitization is reduction in sensitivity. Reciprocal mixing isn't the term. Option B (Quieting): Incorrect. Quieting is FM receiver noise reduction, not reduction in sensitivity - desensitization is reduction in sensitivity. Quieting isn't the term. Option D (Cross modulation interference): Incorrect. Cross modulation is modulation transfer, not reduction in sensitivity - desensitization is reduction in sensitivity. Cross modulation isn't the term.

Exam Tip

Reduction in sensitivity from strong nearby signal = desensitization. Think 'D'esensitization = 'D'iminishes 'S'ensitivity. Strong nearby signals reduce receiver sensitivity. Not reciprocal mixing, not quieting, not cross modulation - just desensitization.

Memory Aid

Reduction in sensitivity from strong nearby signal = desensitization. Think 'D'esensitization = 'S'ensitivity 'R'eduction. Strong nearby signals reduce receiver sensitivity. Important for receiver performance.

Real-World Example

A strong signal near the received frequency: It causes a reduction in receiver sensitivity, which is called desensitization. The strong signal overloads the receiver front-end, reducing its ability to receive weak signals. This is the term - desensitization.

Source & Coverage

Question Pool: 2024-2028 Question Pool

Subelement: E4D

Reference: 2024-2028 Question Pool · E4 - Amateur Practices

Key Concepts

Reduction in receiver sensitivity Strong signal near received frequency Desensitization Receiver sensitivity

Verified Content

Question from the official FCC Extra Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the E4D topic.