Question
What is the characteristic of the JT65 mode?
Answer Options
- A) Uses only a 65 Hz bandwidth
- B) Decodes signals with a very low signal-to-noise ratio
- C) Symbol rate is 65 baud
- D) Permits fast-scan TV transmissions over narrow bandwidth
Correct Answer: B
Explanation
JT65, also developed by Joe Taylor (K1JT), was originally designed for Earth-Moon-Earth (EME) communication but became popular on HF for extreme weak-signal DXing. The mode is characterized by long, synchronized 60-second transmission cycles and a unique modulation structure that includes sophisticated Forward Error Correction (FEC).
Due to this design, the key characteristic of JT65 is its ability to decode signals with a very low signal-to-noise ratio (SNR), often deep below the noise floor. A station can successfully decode a signal that is imperceptible to the human ear on SSB or CW. This sensitivity makes it highly effective for marginal propagation conditions.
This topic was automatically created to facilitate community discussion about this exam question. Feel free to share study tips, memory tricks, or additional explanations!