Thanks Bill. I think we can conclude from this that when we see deltas that are small positive values, we’re all on the right track. May I suggest that we summarize this in the document?
73 Dave / NX6D ________________________________ From: Bill Somerville <g4...@classdesign.com> Sent: Tuesday, December 4, 2018 2:25:51 PM To: wsjt-devel@lists.sourceforge.net Subject: Re: [wsjt-devel] DT, exactly what does it mean? On 04/12/2018 22:11, David Fisher wrote: I see “DT” values that range from about 0.0 to about 0.5 in my system. Does this mean that, on average, my system clock is a little slow, or a little fast? I’ve searched the documentation. It explains that the column of numbers show the difference between the signal and the system’s time, but it doesn’t explain if the calculation is “signal – system” or “system – signal”. FWIW, my guess is that the value is “system – signal” and that the 200 or 300ms delta is due to signal processing delays in the radio. In my case, 2 to 300 ms processing delays could be considered about right, given the DSP filtering. Thanks. Dave / NX6D The DT figure is the measured difference between your PC clock and the sync of a decoded signal. A positive DT implies that the signal clock is behind yours. Positive components of the DT are the sender's clock being slow, and propagation delay. Also contributing are latencies including audio buffering and other processing delay which can be at either of both ends of the link and like propagation delay can only increase the DT, net clock difference can contribute a negative or a positive DT component. 73 Bill G4WJS.
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