Hi all, One of the fun things about WSPR is the frequency accuracies that are involved. Having WSPR mode in WSJT-X motivates some serious thought about how best to handle frequency calibration errors in transceivers.
Typical dial readout errors in modern radios are a few parts per million -- for example, a 20 Hz error at 14 MHz. For JT65 or JT9 such discrepancies are not very important. But the WSPR sub-bands in conventional use since 2008 are only 200 Hz wide, and we'd like to use all of that range effectively. If my transceiver's dial reads 20 Hz low, and yours reads 20 Hz high, and we both set our dials to the conventional 14.0956 MHz for 20 meters, after setting our WSPR Tx frequencies at random within the 200 Hz sub-band there's something like a 20% chance that we won't decode one another. Earlier production versions of WSPR have handled these issues in a rather sophisticated way. The User's Guide includes detailed instructions for determining calibration constants for your transceiver using over-the-air signals (see Appendix C of http://physics.princeton.edu/pulsar/K1JT/WSPR_3.0_User.pdf ). The resulting accuracies can be better than 1 Hz. If CAT control is in use and "Enable frequency correction" is ticked on WSPR's "Advanced Setup" window, frequencies sent to the radio are adjusted so as to compensate for the dial errors. For example, if 14.0956 MHz has been requested, the command for 14095620 Hz may be sent to the radio. I picture this being implemented in WSJT-X in a similar way. In this example, the radio dial would read 14.096520. I'm suggesting that the frequency readout on the WSJT-X screen would read 14.095600, the supposedly "true" frequency. Comments and suggestions would be welcome. -- 73, Joe, K1JT ------------------------------------------------------------------------------ One dashboard for servers and applications across Physical-Virtual-Cloud Widest out-of-the-box monitoring support with 50+ applications Performance metrics, stats and reports that give you Actionable Insights Deep dive visibility with transaction tracing using APM Insight. http://ad.doubleclick.net/ddm/clk/290420510;117567292;y _______________________________________________ wsjt-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/wsjt-devel
