Mike and Bill, WSJT-X does three decoding passes, where a “pass” consists of the following steps:
1. do spectral analysis and make a list of likely FT8 signal candidates, sorted in order of increasing offset frequency. If a candidate is found near the current Rx frequency, put that candidate at the top of the list. 2. try to sync each candidate and, if successful, attempt to decode multiple times using different methods for symbol detection and using different amounts of a priori (AP) info, depending on the current state of the QSO progress indicator 3. for each successful decode, subtract the signal from the audio waveform before attempting to decode the next candidate on the list. Your screenshot shows that your rx frequency was set to something near 1824 Hz offset, and that successful decodes were obtained on the first two passes. No decodes were obtained on the third pass in the example that you provided. 73 Steve k9an > On Dec 26, 2019, at 9:06 AM, Bill Somerville <g4...@classdesign.com> wrote: > > Mike, > > I don't see any evidence of a 4th decoding pass in the list of decodes you > provided in your OP. What makes you think there is such a pass? > > I see a single decode at 1824 Hz which I assume is at or very near you > currently set Rx audio offset, I see 24 decodes in ascending frequency offset > followed by another 4 from the final pass, again in ascending frequency > offset order. > > Decodes are processed sequentially, there is no "still being worked on". AP > decodes, if enabled, will be tried if the non-AP decoding attempts have > failed to produce a decode for a candidate, before moving on to the next > candidate in a decoding pass. > > 73 > Bill > G4WJS. > > On 26/12/2019 14:56, Black Michael via wsjt-devel wrote: >> OK...let's call it 4-pass then....I wasn't including the rx offset as pass#1. >> >> I didn't think anything was happening after what you're calling the 3rd pass >> occurs...but 3 more decodes show up. >> So that's the AP or some decodes are still being worked on after the 3rd >> pass? >> >> Mike >> >> >> On Thursday, December 26, 2019, 08:50:50 AM CST, Bill Somerville >> <g4...@classdesign.com> <mailto:g4...@classdesign.com> wrote: >> >> >> On 26/12/2019 14:36, Black Michael via wsjt-devel wrote: >> >> > Is there a 3-pass going on now in 2.1.2? >> > I'm seeing 3 passes from the decodes..... >> > de Mike W9MDB >> >> Mike, >> >> >> this is nothing new. The first decode attempt is at the Rx audio offset, >> then another across the passband, and a third after subtracting >> facsimiles of the decodes so far. There are also different decoding >> strategies attempted on each candidate signal depending on the decoding >> depth settings and whether AP decoding is enabled, at least until a >> successful decode is achieved for each candidate. >> >> 73 >> Bill >> G4WJS. > > _______________________________________________ > wsjt-devel mailing list > wsjt-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/wsjt-devel
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