Thanks both Bill and Joe, that is certainly a very worthwhile improvement, thanks to the team for the effort! I will read everything with interest.
Regards Conrad PA5Y ________________________________ From: Joe Taylor <j...@princeton.edu> Sent: 17 July 2019 15:33 To: WSJT software development Subject: Re: [wsjt-devel] GMSK waveform generation details Hi Conrad, On 7/17/2019 4:09 AM, Conrad PA5Y wrote: > Hello Joe I am quite interested to learn more about the GMSK waveform > generation, where can I read more about it and the implementation in > WSJT-X and the advantages. A good place to start would be our document describing FT4 during its early development, especially pages 3 and 4: http://physics.princeton.edu/pulsar/k1jt/FT4_Protocol.pdf Bill gave you pointers to the code that generates GMSK waveforms for FT4 and FT8. Main advantages: - constant envelope waveform, - peak-to-average power ratio = 1.0 - very clean spectrum Plots of spectral measurements you may find interesting: http://physics.princeton.edu/pulsar/k1jt/rtty_ft8_ft4_spec.png http://physics.princeton.edu/pulsar/k1jt/FT8_FSK_GFSK.png For comparison, the first plot shows spectra of a standard RTTY signal, FT8 as generated with WSJT-X 2.0, FT8 with WSJT-X 2.1, and FT4. The second plot shows examples of FSK and GFSK versions of FT8, captured from on-the-air signals. The signals happen to have nearly identical strengths. The much cleaner spectrum of the new FT8 is easy to see on the waterfall as well as the graphed spectrum. -- 73, Joe, K1JT _______________________________________________ wsjt-devel mailing list wsjt-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/wsjt-devel
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