Deep Dive: G8A01
The correct answer is B: By changing an oscillator's frequency directly with a digital control signal. How direct binary FSK modulation is generated is by changing an oscillator's frequency directly with a digital control signal. FSK (Frequency Shift Keying) directly shifts the oscillator frequency based on digital data. For amateur radio operators, this is how digital FSK works. Understanding this helps when operating digital modes.
Why Other Answers Are Wrong
Option A: Incorrect. FSK isn't generated by keying FM transmitter with sub-audible tone - that's tone signaling, not FSK. Sub-audible tones aren't FSK. Option C: Incorrect. FSK isn't generated by using transceiver's computer interface to change frequencies - that's frequency control, not modulation. Computer interface isn't for modulation. Option D: Incorrect. FSK isn't generated by reconfiguring CW keying input as tone generator - that's CW keying, not FSK. CW keying isn't FSK.
Exam Tip
Direct binary FSK = change oscillator frequency with digital control signal. Think 'F'SK = 'F'requency 'S'hift 'K'eying = 'F'requency 'S'hifts with 'K'eying. FSK directly shifts oscillator frequency based on digital data. Not sub-audible tone, not computer interface, not CW keying - just direct frequency control.
Memory Aid
Direct binary FSK = change oscillator frequency with digital control signal. Think 'F'SK = 'F'requency 'S'hifts with 'K'eying. FSK directly shifts oscillator frequency based on digital data. Direct frequency control method.
Real-World Example
Direct binary FSK: A digital control signal (0 or 1) directly changes the oscillator frequency. For '0', oscillator is at one frequency; for '1', oscillator shifts to another frequency. This is direct FSK - the oscillator frequency is directly controlled by the digital signal. This is how FSK modulation works.
Source & Coverage
Question Pool: 2023-2027 Question Pool
Subelement: G8A
Reference: 2023-2027 Question Pool · G8 - Signals and Emissions
Key Concepts
Verified Content
Question from the official FCC General Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the G8A topic.