Deep Dive: G7C05
The correct answer is D: Variable output frequency with the stability of a crystal oscillator. A characteristic of a direct digital synthesizer (DDS) is variable output frequency with the stability of a crystal oscillator. DDS generates frequencies digitally while maintaining crystal oscillator stability. For amateur radio operators, this provides precise, stable frequency generation. Understanding this helps when using modern transceivers.
Why Other Answers Are Wrong
Option A: Incorrect. DDS doesn't have extremely narrow tuning range - DDS can tune over wide ranges. Narrow range isn't a characteristic. Option B: Incorrect. DDS doesn't have relatively high-power output - DDS generates low-level signals that need amplification. High power isn't a characteristic. Option C: Incorrect. DDS doesn't necessarily produce pure sine wave output - DDS can have spurious signals. Pure sine wave isn't guaranteed.
Exam Tip
DDS characteristic = variable frequency with crystal stability. Think 'D'DS = 'D'igital 'D'irect 'S'ynthesizer = 'V'ariable 'F'requency with 'S'tability. DDS generates frequencies digitally while maintaining crystal oscillator stability. Not narrow range, not high power, not pure sine - just variable frequency with stability.
Memory Aid
DDS characteristic = variable frequency with crystal stability. Think 'D'DS = 'V'ariable 'F'requency with 'S'tability. DDS generates frequencies digitally while maintaining crystal oscillator stability. Key DDS advantage.
Real-World Example
A DDS in a modern transceiver: You can tune across a wide frequency range (e.g., entire HF band), and the frequency is as stable as a crystal oscillator. DDS generates frequencies digitally (variable) while maintaining crystal stability. This is a key advantage of DDS - variable frequency with crystal stability.
Source & Coverage
Question Pool: 2023-2027 Question Pool
Subelement: G7C
Reference: 2023-2027 Question Pool · G7 - Practical Circuits
Key Concepts
Verified Content
Question from the official FCC General Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the G7C topic.