Question
What type of modulation is used by JT65?
Answer Options
- A) Multitone AFSK
- B) PSK
- C) RTTY
- D) QAM
Correct Answer: A
Explanation
JT65 is a highly specialized weak-signal digital mode designed to communicate under extreme noise conditions, such as EME. It relies on transmitting a very narrow-band signal that changes frequency multiple times during its 60-second transmission period to encode the message data.
The type of modulation used by JT65 is Multitone AFSK (Audio Frequency-Shift Keying). The ‘65’ in its name refers to the fact that it uses 65 tones, where the information is conveyed by shifting the audio frequency between these 65 discrete tones. This combination of AFSK over a standard SSB transmitter allows the powerful decoding software to exploit the frequency diversity for reliable data recovery.
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