Deep Dive: T8A02
The correct answer is A: FM or PM. FM (Frequency Modulation) or PM (Phase Modulation) is commonly used for VHF packet radio transmissions. Packet radio on VHF typically uses 1200 or 9600 baud AFSK (Audio Frequency Shift Keying), which is a form of FM. The digital data modulates an audio tone, which then frequency-modulates the RF carrier. For amateur radio operators, FM packet radio is the standard for VHF data communications, used for APRS, bulletin boards, and digital messaging. Understanding this helps when setting up packet radio stations.
Why Other Answers Are Wrong
Option B (SSB): Incorrect. SSB is used for voice and some digital modes on HF, but not typically for VHF packet radio. VHF packet uses FM. Option C (AM): Incorrect. AM is not commonly used for VHF packet radio. FM is the standard for VHF data communications. Option D (PSK): Incorrect. PSK is a digital modulation mode used on HF, not typically for VHF packet radio. VHF packet uses FM/PM.
Exam Tip
VHF packet radio = FM or PM. Think 'V'HF 'P'acket = 'V'oice band 'F'M. Packet radio on VHF uses FM modulation, typically 1200 or 9600 baud AFSK. SSB, AM, and PSK are used for other applications.
Memory Aid
VHF packet radio = FM or PM. Think 'V'HF 'P'acket = 'V'oice band 'F'M. Uses frequency modulation for digital data transmission on VHF bands.
Real-World Example
Your VHF packet radio station uses FM modulation. The TNC (Terminal Node Controller) generates audio tones (mark and space) that frequency-modulate your 2-meter transmitter. This FM signal carries the digital packet data. FM is ideal for VHF because it's less affected by noise and works well with the FM repeaters commonly used on VHF.
Source & Coverage
Question Pool: 2022-2026 Question Pool
Subelement: T8A
Reference: 2022-2026 Question Pool · T8 - Signals and emissions
Key Concepts
Verified Content
Question from the official FCC Technician Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the T8A topic.