=== New in Version {VERSION}

*Improvements to decoders*

*FT4:* Corrected bugs that prevented AP (_a priori_) decoding and/or
multi-pass decoding in some circumstances.  Improved the algorithm for
AP decoding.

*FT8:* Decoding is now spread over three intervals.  The first starts
11.8 s into an Rx sequence and typically yields around 85% of the
possible decodes, so you see all of these decodes much earlier than
before.  A second processing step starts at 13.5 s, and the final one
at 14.7 s.  Overall decoding yield on the most crowded bands is
improved by 10% or more.  Systems with receive latency greater than
0.2 s will see smaller improvements, but will still see many decodes
earlier than before.  In FT8 DXpedition Mode, AP decoding is now
implemented for Hounds when the Fox has a compound callsign.

SNR estimates no longer saturate at +20 dB, and large signals in the
passband no longer cause the SNR of weaker signals to be biased low.
Times written to cumulative journal file ALL.TXT are now correct even
when the decode occurs after the T/R sequence boundary.

*JT4:*  Formatting and display of averaged and Deep Search decodes has
been cleaned up and made consistent with other modes used for EME and
extreme weak-signal work at VHF and above.

*JT65:*  Many improvements have been made for averaged and Deep Search
decodes and their display to the user.  For details see <<VHF_JT65,JT65>>
in the <<VHF_AND_UP,VHF+ Features>> section.

*WSPR:* Significant improvements have been made to the WSPR decoder's
sensitivity, its ability to cope with many signals in a crowded
sub-band, and its rate of undetected false decodes.  We now use up to
three decoding passes.  Passes 1 and 2 use noncoherent demodulation of
single symbols and allow for frequency drifts up to ±4 Hz in a
transmission.  Pass 3 assumes no drift and does coherent block
detection of up to three symbols.  It also applies bit-by-bit
normalization of the single-symbol bit metrics, which has proven
helpful for signals corrupted by artifacts of the subtraction of
stronger signals and also for LF/MF signals heavily contaminated by
lightning transients.  With these improvements the number of decodes in a
crowded WSPR sub-band typically increases by 10 to 15%.

*New message format:* When *EU VHF Contest* is selected, the Tx2 and
Tx3 messages -- those conveying signal report, serial number, and
6-character locator -- now use hashcodes for both callsigns .  This
change is not backward compatible with earlier versions of _WSJT-X_.
See <<CONTEST_MSGS,Contest Messages>> for details.

*New modes FT4W and FT4S* are now available for use with extremely
weak signals on the LF and MF bands.

*FT4W* behaves like WSPR but uses different schemes for coding and
modulation.  On the AWGN (Additive White Gaussian Noise) channel and
with 2-minute T/R sequences, FT4W is about 1.5 dB more sensitive than
WSPR, even with the enhanced decoder outlined above.  With 5-minute
T/R sequences FT4W reaches a threshold sensitivity close to -37 dB.

*FT4S* is desighned for 2-way QSOs on the 620 amd 2200 m bands.  It
uses the same message formats as FT4, FT8, and MSK144, but different
coding and modulation and much slower T/R sequences lasting 2 minutes.
We intend FT4S to be a replacement for JT9 on the LF and MF bands.

*Minor enhancements and bug fixes*

- *Save None* now writes no .wav files to disk, even temporarily.

- An explicit entry *WW Digi Contest* has been added to *Special
 operating activities* on the *Settings | Advanced* tab.

- The contest mode FT4 now always uses RR73 for the Tx4 message.

- *Keyboard shortcuts* have been added as an aid to accessibility:
*Alt+R* sets Tx4 message to RR73, *Ctrl+R* sets it to RRR.

- The *Status bar* now displays the number of decodes found in the
most recent Rx sequence.

=== Documentation Conventions

In this manual the following icons call attention to particular types
of information:

NOTE: *Notes* containing information that may be of interest to
particular classes of users.

TIP: *Tips* on program features or capabilities that might otherwise be
overlooked.

IMPORTANT: *Warnings* about usage that could lead to undesired
consequences.

=== How You Can Contribute

_WSJT-X_ is part of an open-source project released under the
{gnu_gpl} (GPLv3). If you have programming or documentation skills or
would like to contribute to the project in other ways, please make
your interests known to the development team.  The project's
source-code repository can be found at {devrepo}, and communication
among the developers takes place on the email reflector {devmail}.
Bug reports and suggestions for new features, improvements to the
_WSJT-X_ User Guide, etc., may be sent there as well.  You must join
the group before posting to the email list.
