T7A04: Receiver selectivity: Term describes the ability of a receiver

Q: Which term describes the ability of a receiver to discriminate between multiple signals?

The correct answer is C: Selectivity. The correct answer is Selectivity. Selectivity describes the ability of a receiver to discriminate between multiple signals - to separate a desired signal from unwanted nearby signals. Selectivity is determined by the receiver's filters, particularly the IF (intermediate frequency) filters, which determine how narrow the receiver's response is. High selectivity means the receiver can separate closely spaced signals, while low selectivity means it might receive multiple signals simultaneously. For amateur radio operators, good selectivity is essential when operating in crowded band conditions, near strong local stations, or when trying to copy weak signals near strong ones. Selectivity is different from sensitivity (ability to detect weak signals) and is measured by the receiver's bandwidth and filter characteristics.

Updated: Dec 9, 2025 | Source: 2022-2026 Question Pool | Topic: T7A

T7A04T7A

Which term describes the ability of a receiver to discriminate between multiple signals?

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Deep Dive: T7A04

The correct answer is Selectivity. Selectivity describes the ability of a receiver to discriminate between multiple signals - to separate a desired signal from unwanted nearby signals. Selectivity is determined by the receiver's filters, particularly the IF (intermediate frequency) filters, which determine how narrow the receiver's response is. High selectivity means the receiver can separate closely spaced signals, while low selectivity means it might receive multiple signals simultaneously. For amateur radio operators, good selectivity is essential when operating in crowded band conditions, near strong local stations, or when trying to copy weak signals near strong ones. Selectivity is different from sensitivity (ability to detect weak signals) and is measured by the receiver's bandwidth and filter characteristics.

Why Other Answers Are Wrong

Option A (Discrimination ratio): Incorrect. This is not a standard receiver specification. While it sounds similar to selectivity, the correct term is 'selectivity.' Option B (Sensitivity): Incorrect. Sensitivity describes the ability to detect weak signals, not to separate multiple signals. It's about signal detection, not signal separation. Option D (Harmonic distortion): Incorrect. Harmonic distortion measures how much the receiver adds unwanted harmonics to the signal. It's a quality metric, not a measure of signal separation ability.

Exam Tip

Selectivity = separating signals. Think 'S'electivity = 'S'electing one signal from many. Sensitivity detects weak signals, selectivity separates signals. The key word is 'discriminate between multiple signals.'

Memory Aid

Selectivity = Selecting one signal from many. Think 'S'electivity = 'S'eparating 'S'ignals. Different from sensitivity (detecting weak signals).

Real-World Example

When operating on a crowded 2-meter repeater frequency, your receiver's selectivity determines whether you can copy the desired signal or if nearby strong signals interfere. A receiver with good selectivity (narrow filters) can separate signals only 5 kHz apart, while poor selectivity might allow interference from signals 20 kHz away. This is crucial in urban areas with many active stations.

Source & Coverage

Question Pool: 2022-2026 Question Pool

Subelement: T7A

Reference: 2022-2026 Question Pool · T7 - Practical circuits

Key Concepts

Receiver selectivity Signal discrimination Filter bandwidth Receiver performance

Verified Content

Question from the official FCC Technician Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the T7A topic.