*Question G8C11:
How are the two separate frequencies of a Frequency Shift Keyed (FSK) signal identified?*  

*Correct Answer is  D: Mark and space*  

### AI Response: (may contain errors)  

To identify the two separate frequencies of a Frequency Shift Keyed (FSK) signal, we use the terms "mark" and "space." 

### Explanation of the Correct Answer:
- **Mark and Space**: 
  - In FSK, the "mark" frequency represents a binary '1', while the "space" frequency represents a binary '0'. This modulation technique shifts the frequency of the carrier signal between these two distinct frequencies to convey digital information.

### Why the Other Choices are Incorrect:
- **A: Dot and dash**: 
  - This terminology is associated with Morse code, not FSK. Morse code uses short and long signals (dots and dashes) to represent letters and numbers, which is unrelated to frequency shifts.
  
- **B: On and off**: 
  - This choice refers to a simple on-off keying (OOK) method, where the signal is either present (on) or absent (off). It does not involve frequency changes, which are central to FSK.
  
- **C: High and low**: 
  - While this could describe signal levels, it does not accurately represent the frequency shifts in FSK. FSK specifically uses distinct frequencies rather than just high or low signal levels.

### Summary:
In FSK, the two frequencies are specifically termed "mark" and "space," which directly relate to the binary data being transmitted. Understanding these terms is crucial for recognizing how FSK modulation works in amateur radio communications.