Updated: Dec 9, 2025 | Source: 2023-2027 Question Pool | Topic: G8C
G8C11G8C

How are the two separate frequencies of a Frequency Shift Keyed (FSK) signal identified?

Deep Dive: G8C11

The correct answer is D: Mark and space. The two separate frequencies of a Frequency Shift Keyed (FSK) signal are identified as mark and space. Mark and space are the traditional terms for the two FSK frequencies (mark = one frequency, space = the other). For amateur radio operators, this is standard FSK terminology. Understanding this helps when operating FSK modes.

Why Other Answers Are Wrong

Option A (Dot and dash): Incorrect. Dot and dash are for CW (Morse code), not FSK - FSK uses mark and space frequencies. Dot/dash are different. Option B (On and off): Incorrect. On and off are too general - FSK uses specific frequency terms (mark and space). On/off aren't the FSK terms. Option C (High and low): Incorrect. High and low are too generic - FSK uses mark and space, not high/low. High/low aren't the standard FSK terms.

Exam Tip

FSK two frequencies = mark and space. Think 'F'SK = 'F'requency 'S'hift 'K'eying = 'M'ark and 'S'pace. Mark and space are the traditional terms for the two FSK frequencies. Not dot/dash (CW), not on/off, not high/low - just mark and space.

Memory Aid

FSK two frequencies = mark and space. Think 'F'SK = 'M'ark and 'S'pace. Mark and space are the traditional terms for the two FSK frequencies. Standard FSK terminology.

Real-World Example

An FSK signal: One frequency represents 'mark' (logical 1), another frequency represents 'space' (logical 0). The signal shifts between these two frequencies to encode data. Mark and space are the standard terms for FSK frequencies - this is how FSK signals are identified.

Source & Coverage

Question Pool: 2023-2027 Question Pool

Subelement: G8C

Reference: 2023-2027 Question Pool · G8 - Signals and Emissions

Key Concepts

FSK Mark and space Two frequencies Frequency shift keying

Verified Content

Question from the official FCC General Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the G8C topic.