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سؤال 109

What is the characteristic of the JT65 mode?

  1. Uses only a 65 Hz bandwidth
  2. Decodes signals with a very low signal-to-noise ratioپاسخ درست
  3. Symbol rate is 65 baud
  4. Permits fast-scan TV transmissions over narrow bandwidth

توضیح

JT65 was designed for moonbounce, where signals sit far below the noise, and its heavy forward error correction and slow symbol rate let it decode signals well below what the ear can hear. Its bandwidth is set by 65 tones and it is much slower than 65 baud, so the other descriptions do not fit.

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شروع تمرین
سؤال 109: What is the characteristic of the JT65 mode? · FCC Amateur Extra Class (Element 4) · Questena