Question
What is the standard sideband for JT65, JT9, FT4, or FT8 digital signal when using AFSK?
Answer Options
- A) LSB
- B) USB
- C) DSB
- D) SSB
Correct Answer: B
Explanation
The popular WSJT-X suite of weak-signal digital modes, including JT65, JT9, FT4, and FT8, are transmitted using Audio Frequency-Shift Keying (AFSK) via an Single Sideband (SSB) transceiver. The standard convention for these modes on HF is to operate the transceiver in Upper Sideband (USB), regardless of the band.
Although the general HF convention is LSB below 10 \text{MHz} and USB above 10 \text{MHz}, these specific weak-signal modes are universally operated in USB on all bands. This is due to the way the software interprets the audio tones and ensures that the total signal bandwidth is placed correctly in the amateur band and is compatible with other users of the software.
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