Question
What is the most common frequency shift for RTTY emissions in the amateur HF bands?
Answer Options
- A) 85 Hz
- B) 170 Hz
- C) 425 Hz
- D) 850 Hz
Correct Answer: B
Explanation
Radio Teletype (RTTY) uses Frequency-Shift Keying (FSK), where two distinct frequencies are used to represent the mark and space states. The difference between these two frequencies is called the frequency shift. On the amateur HF bands, the most common and internationally accepted frequency shift for RTTY operation is 170 \text{Hz}.
Although other shifts like 850 \text{Hz} were common decades ago, 170 \text{Hz} is the current de facto standard. Adhering to this narrow shift is essential for digital mode compatibility, ensuring that the receiving station’s decoder can correctly interpret the transmitted signal.
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