Hi Joe,

I just built and ran r6020 on Win32. Leaving ntrials at [6], it appears the start receive time is being delayed a by about 1 second ? This is JT65+JT9 mode.

I'm also getting a Fortran error at decode. See attached image.

73's
Greg, KI7MT


On 10/29/2015 10:19, Joe Taylor wrote:
Hi all,

WSJT-X v1.6.1 now (SVN revision 6020) includes a first cut at using
Steve's 2-pass decoding scheme for JT65.

As you will have seen in previous posts by Steve and me -- based on use
of a stand-alone, single-purpose program -- the 2-pass scheme produces
significantly more decodes from crowded band segments.  In both passes
it uses the "sfrsd" algorithm rather than the patented, closed-source
algorithm of kvasd.

Here's an update on the table I shared here on 10/2/2015, summarizing
JT65 decoding performance of JT65-HF-HB9HQX-Edition and several versions
of WSJT-X.  All programs analyzed exactly the same data, recorded (by
WSJT-X r5912) on 20 meters.

              Correct   False
Program      Decodes  Decodes   Decoder
------------------------------------------------------------
JT65-HF        2329      24    BM + kvasd
WSJT-X r5912   2249       0    BM + kvasd
WSJT-X r5955   2114       0    BM + sfrsd
WSJT-X r5955   1816       0    BM only
WSJT-X r6020   2874       0    BM + sfrsd (N=1000) + 2-pass


If you've been following SVN updates and relevant posts made here you
will know that I've also been experimenting with "experience-based"
decoding of JT65 signals.  So far this has been done in SVN trunk, the
WSJT branch.  I will soon start work on merging this code into WSJT-X.
This will require making some distinction between HF-style
"multi-decoding" of all JT65 signals found in the received passband, and
VHF/UHF/Microwave/EME-style decoding where one (or a small number)
signals are expected to be present in the passband.


The new JT65 decoder has some user-adjustable parameters (see attached
screen shot of the "Settings | Advanced" tab).  At present the only one
activated is a spinner that sets the number of random erasure patterns
tried in the sfrsd algorithm.  The default setting is "6", which sets
variable ntrials = 1000.  Other settings as follows:

Setting  ntrials
--------------------------
0           0  ==> BM only
1           3
2          10
3          30
4         100
5         300
6       1,000
7       3,000
8      10,000
9      30,000
10    100,000
11    300,000
12  1,000,000

Bigger numbers generally mean slower decodes.

As always, feedback is encouraged!

     -- 73, Joe, K1JT


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