Updated: Dec 9, 2025 | Source: 2024-2028 Question Pool | Topic: E2D
E2D07E2D

What digital protocol is used by APRS?

Deep Dive: E2D07

The correct answer is C: AX.25. What digital protocol is used by APRS is AX.25. APRS uses the AX.25 packet radio protocol. For amateur radio operators, this is important for APRS operation. Understanding this helps when operating APRS.

Why Other Answers Are Wrong

Option A (PACTOR): Incorrect. PACTOR isn't used by APRS - APRS uses AX.25. PACTOR isn't the protocol. Option B (QAM): Incorrect. QAM isn't a packet protocol - APRS uses AX.25 packet protocol. QAM isn't the protocol. Option D (AMTOR): Incorrect. AMTOR isn't used by APRS - APRS uses AX.25. AMTOR isn't the protocol.

Exam Tip

APRS protocol = AX.25. Think 'A'PRS = 'A'X.25. APRS uses the AX.25 packet radio protocol. Not PACTOR, not QAM, not AMTOR - just AX.25.

Memory Aid

APRS protocol = AX.25. Think 'A'PRS = 'A'X.25. APRS uses the AX.25 packet radio protocol. Important for APRS operation.

Real-World Example

APRS (Automatic Packet Reporting System): It uses the AX.25 digital protocol. AX.25 is a packet radio protocol based on X.25. APRS packets are formatted according to AX.25. This is the protocol - AX.25 is used by APRS.

Source & Coverage

Question Pool: 2024-2028 Question Pool

Subelement: E2D

Reference: 2024-2028 Question Pool · E2 - Operating Procedures

Key Concepts

APRS Digital protocol AX.25 Packet radio

Verified Content

Question from the official FCC Extra Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the E2D topic.