Hi Tomáš, Thanks for your message. Perhaps a slightly more informative description of the JT65 tone frequencies could be put into the WSJT-X User Guide.
The second sentence of the section from which you quote advises the interested user to read the full detailed description of the protocol in a paper published in the ARRL journal QEX: http://physics.princeton.edu/pulsar/K1JT/JT65.pdf You will find the description you are looking for at the top of page 8. Incidentally, the right-parenthesis in your expression "1270.5 + (11025/4096) × (2 + N × m) Hz" is misplaced. Your formula should read "1270.5 + (11025/4096) × (2 + N) × m Hz" -- 73, Joe, K1JT On 4/8/2015 9:20 AM, Tomáš Klinkovský OK2TKB wrote: > I would like to suggest a minor modification of the JT65 protocol > description. > > The current documentation says: "Each channel symbol generates a tone at > frequency 1275.8 + 2.6917 × N × m Hz". Actually the origin of these two > magic constant 1275.8 and 2.6917 is not immediately clear. However, if we > rewrite it as "1270.5 + (11025/4096) × (2 + N × m) Hz" it becomes evident > that: > > - everything is derived from the synchronization frequency 1270.5 Hz > > - the frequency step is a rational number whose parts correspond to the > value shown before (the symbol duration 4096/11025 seconds) > > - there is a single step hole between the synchronization frequency and the > first symbol frequency. > > It is also not fully clear why the documentation speaks about the 1270.5 Hz > synchronization frequency while the actual HAM traffic successfully uses > various synchronization frequencies. > > Please understand me, the current documentation is not wrong. I am only > describing my problems that occurred when I tried to reconstruct the encoder > behaviour according to the documentation. > > Thanks for understanding. > > Tomáš > OK2TKB ------------------------------------------------------------------------------ BPM Camp - Free Virtual Workshop May 6th at 10am PDT/1PM EDT Develop your own process in accordance with the BPMN 2 standard Learn Process modeling best practices with Bonita BPM through live exercises http://www.bonitasoft.com/be-part-of-it/events/bpm-camp-virtual- event?utm_ source=Sourceforge_BPM_Camp_5_6_15&utm_medium=email&utm_campaign=VA_SF _______________________________________________ wsjt-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/wsjt-devel
