Date: Mon, 3 Jul 2017 20:14:39 +0100
From: Bill Somerville <g4...@classdesign.com>
To: wsjt-devel@lists.sourceforge.net
Subject: Re: [wsjt-devel] Inquiry about sending .wav files with failed
decodes to development team
Message-ID: <1bf00903-804a-a94f-c5d7-391a7e848...@classdesign.com>
Content-Type: text/plain; charset="windows-1252"; Format="flowed"
On 03/07/2017 20:02, K5GZR - Rick wrote:
>
> I?m new to this list, wanting to send some .wav files with FT8 signals
> which didn?t decode, even though their tracks on the waterfall looked
> ?good?. I see some emails to the list with one or two .wav files
> attached, but I have quite a few more than that. I put them into a
> .zip archive and the .zip is 10 megabytes? probably too much for an
> e-mail attachment.
>
> Should I just pick one or two and attach them to an email and send it
> to the list? Or is it better to try to send more files, and if so is
> there a ?normal? way to make them available to the developers, other
> than attaching them to an e-mail? I don?t want to cause ?information
> overload?.
>
> Thanks in advance,
>
> Rick ? K5GZR ? EL29gp
>
Hi Rick,
providing a link to a cloud storage service where the files or archive
have been uploaded is best. Dropbox, Google Drive etc. provide ample
free storage.
Best to try and categorize types of failures, if you can, and provide a
file name that best demonstrates what you think should decode per category.
You should be aware that users used to operating JT9 or JT65 may have
over-optimistic expectations of FT8 sensitivity. The mode was designed
to balance sensitivity, bandwidth and transmit period so as to carry the
same information content as JT65 and JT9 in a multi-decoding
environment, something has to give to achieve the roughly 1/4 as long
transmissions and in this case it is both bandwidth (vs. JT9) and
sensitivity. Currently around -21dB SNR with respect to a 2500Hz noise
bandwidth is about the limit. Reported SNR estimates may not yet be
accurate although they are being improved as the decoder is fine tuned.
Examples of non-decodes are welcome but be prepared for a simple "You
are expecting too much." response in some cases.
73
Bill
G4WJS.
*****************************************
Thanks Bill,
Couldn't figure out how to reply on the SourceForge site. Sorry about
possible weird reply format.
Thanks for your reply. Putting the files on a cloud site will work for me
when I need to send files to the team at some time in the future.
In this case, the weak signal sequences (S1 or lower) decoded, but the
strong signal sequences (S5 to S6) from the same station did not decode.
Both the weak and strong signal sequences had reasonably constant strengths
throughout the sequences, with no fades and no MS pings. WSJT-X release was
r7777.
I'll continue to test and get a better idea of what 'should' decode and
focus on situations where there is no decode where it looks like it
'should'. 73, Rick - K5GZR
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