The way the information and parity is encoded is specially designed for the maximum probability of being able to recover the originally transmitted message accurately from the minimum amount of received signal energy.ĬW uses on-off modulation, although it could use frequency shift keying. The receiving end uses very narrow filters implemented in the digital domain and integration for the length of each symbol (the tone being used is a symbol in this case) to ensure that the maximum wanted signal energy is recovered at the tone frequency. The difference between the modes include the number of tones, the rate of keying, the bandwidth, the amount of parity and other information added for detecting the signal, robustness of decoding, and the message information encoding. The output at any particular instant is a single frequency, the information is passed by shifting the frequency between a regularly spaced fixed set, also known as the channel symbol alphabet. Modes like WSPR, JT65, JT9, FT8, FT4, JT4, MSK144 that are available in the WSJT-X application all uses a frequency shift keying modulation. I'm new to Groups and am receiving lots of emails about other answers in the WSTX group, I have just started another Post named CAMERART, would you address any more replies to that address please? Then I'll unsubscribe from this one. I know that the DTMF CODEs are built up using 2x separate frequencies mixed together. Am I correct then than what I'm calling a stepped wave, is actually built up over time, by the TX/RX decoder, e,g, a DTMF CODE? Your explanation of a stepped wave, answers my question.
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