Deep Dive: E2D05
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.
Why Other Answers 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.
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 Example
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.
Source & Coverage
Question Pool: 2024-2028 Question Pool
Subelement: E2D
Reference: 2024-2028 Question Pool · E2 - Operating Procedures
Key Concepts
Verified Content
Question from the official FCC Extra Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the E2D topic.