What is the characteristic of the JT65 mode?
The correct answer is B: Decodes signals with a very low signal-to-noise ratio. What is the characteristic of the JT65 mode is that it decodes signals with a very low signal-to-noise ratio. JT65 is designed for very weak signal work. For amateur radio operators, this is important for weak signal operation. Understanding this helps when operating JT65.
Exam Tip
JT65 characteristic = decodes signals with very low signal-to-noise ratio. Think 'J'T65 = 'J'ust 'T'iny signals (very weak). JT65 is designed for very weak signal work. Not 65 Hz bandwidth, not 65 baud, not fast-scan TV - just very low SNR decoding.
Memory Aid
"JT65 characteristic = decodes signals with very low signal-to-noise ratio. Think 'J'T65 = 'V'ery 'W'eak signals. JT65 is designed for very weak signal work. Important for weak signal operation."
Real-World Application
JT65 mode: It's designed to decode signals with a very low signal-to-noise ratio. JT65 can decode signals that are barely above the noise floor, making it ideal for weak signal work like EME, meteor scatter, or long-distance contacts. This is the characteristic - decodes signals with very low SNR.
Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. Uses only 65 Hz bandwidth isn't the characteristic - JT65 uses about 2.3 kHz bandwidth, not 65 Hz. 65 Hz bandwidth isn't correct.
Option C: Incorrect. Symbol rate is 65 baud isn't the characteristic - JT65 symbol rate is different, and the key characteristic is weak signal decoding. Symbol rate isn't the characteristic.
Option D: Incorrect. Permits fast-scan TV transmissions isn't correct - JT65 is a digital mode, not TV. Fast-scan TV isn't JT65.
题目解析
The correct answer is B: Decodes signals with a very low signal-to-noise ratio. What is the characteristic of the JT65 mode is that it decodes signals with a very low signal-to-noise ratio. JT65 is designed for very weak signal work. For amateur radio operators, this is important for weak signal operation. Understanding this helps when operating JT65.
考试技巧
JT65 characteristic = decodes signals with very low signal-to-noise ratio. Think 'J'T65 = 'J'ust 'T'iny signals (very weak). JT65 is designed for very weak signal work. Not 65 Hz bandwidth, not 65 baud, not fast-scan TV - just very low SNR decoding.
记忆口诀
JT65 characteristic = decodes signals with very low signal-to-noise ratio. Think 'J'T65 = 'V'ery 'W'eak signals. JT65 is designed for very weak signal work. Important for weak signal operation.
实际应用示例
JT65 mode: It's designed to decode signals with a very low signal-to-noise ratio. JT65 can decode signals that are barely above the noise floor, making it ideal for weak signal work like EME, meteor scatter, or long-distance contacts. This is the characteristic - decodes signals with very low SNR.
错误选项分析
Option A: Incorrect. Uses only 65 Hz bandwidth isn't the characteristic - JT65 uses about 2.3 kHz bandwidth, not 65 Hz. 65 Hz bandwidth isn't correct. Option C: Incorrect. Symbol rate is 65 baud isn't the characteristic - JT65 symbol rate is different, and the key characteristic is weak signal decoding. Symbol rate isn't the characteristic. Option D: Incorrect. Permits fast-scan TV transmissions isn't correct - JT65 is a digital mode, not TV. Fast-scan TV isn't JT65.
知识点
JT65 mode, Very low signal-to-noise ratio, Weak signals, JT65 characteristics
Verified Content
Question from official FCC Extra Class question pool. Explanation reviewed by licensed amateur radio operators.