Deep Dive: T8A01
The correct answer is C: Single sideband. Single sideband (SSB) is a form of amplitude modulation (AM). SSB is derived from AM by suppressing the carrier and one sideband, leaving only one sideband (upper or lower) with the audio information. This is more efficient than full AM because it uses less bandwidth and power. For amateur radio operators, SSB is the primary voice mode on HF bands and is also used on VHF/UHF for weak-signal work. Understanding that SSB is a type of AM helps explain its characteristics and why it requires more complex receivers than FM.
Why Other Answers Are Wrong
Option A (Spread spectrum): Incorrect. Spread spectrum spreads the signal across a wide frequency range using techniques like frequency hopping or direct sequence. It's not a form of amplitude modulation. Option B (Packet radio): Incorrect. Packet radio is a digital communications mode using data packets, not amplitude modulation. It's a digital mode, not an analog AM mode. Option D (Phase shift keying): Incorrect. PSK is a digital modulation technique that shifts the phase of the carrier, not amplitude. It's phase modulation, not amplitude modulation.
Exam Tip
SSB = form of AM. Think 'S'ingle 'S'ideband = 'S'uppressed carrier 'A'M. SSB is AM with carrier and one sideband removed. Spread spectrum, packet radio, and PSK are different modulation types.
Memory Aid
SSB = Single Sideband = form of AM. Think 'S'ingle 'S'ideband = 'S'uppressed carrier 'A'M. AM with carrier and one sideband removed for efficiency.
Real-World Example
On 20 meters, most voice communications use SSB, which is a form of AM. Your transceiver generates an AM signal, then suppresses the carrier and one sideband, transmitting only the upper sideband. This is more efficient than full AM - it uses half the bandwidth and all the power goes into the information-carrying sideband, not the carrier.
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.