Hi Yousuf,
Thanks for your email, and your interest in JTTY.
In response to your two questions:
1. Yes, we welcome independent implementations of JTTY if they adhere to
our protocol definitions for source encoding, error-correction coding,
and modulation format.
2. A summary description of the JTTY protocol will be included in the
WSJT-X User Guide with the next GA release. It will be based on the more
detailed descriptions already available in files
jtty_source_encoding.txt and jtty_design.md.
We do not presently anticipate any changes in the defined JTTY protocol,
but if any should happen we will certainly announce them in advance, on
this email list.
-- 73, Joe, K1JT
On 10/27/2026 7:05 AM, Life is simple- Eat- Sleep- Fly 4D via wsjt-devel
wrote:
Dear Joe, dear members of the WSJT Development Team,
I am Yousuf AL Balushi, A41UX, from Oman. I write amateur-radio apps
for iPhone and Android under the name Unixeer, and I am writing as a
courtesy before I publish one of them.
Ham Signaling is a digital-modes app for iPhone and Android. Its first
release, not yet published, will include JTTY as a keyboard mode
beside RTTY, PSK and Olivia, marked "Experimental". I would like you
to hear it from me first, and I have two questions.
How it was built:
• The JTTY codec is jtty_lib from the JTTYAF project (MIT licence,
github.com/patrickrb/JTTYAF
<http://github.com/patrickrb/JTTYAF>),
used unmodified. A second independent implementation, jtty-cuf (MIT,
by OH3CUF), is used only inside our tests, as a cross-check.
• We read your published documentation — the User Guide, the release
notes, and the JTTY description files published with WSJT-X
(jtty_source_encoding.txt and jtty_design.md) — but no WSJT-X program
code, and we checked the result against your released programs as
black boxes.
• With WSJT-X 3.3.0-beta2, rjtty decodes the app's transmissions
exactly, and the app decodes the output of sjtty, including with the
fading models. Your sample recording 260807_134110.wav decodes as "RAN
ALL NIGHT ON BAND NOISE - NO FALSE DECODES!".
• A message is at most 80 characters; the app refuses a longer one
rather than cutting it.
• The app names WSJT-X as the origin of JTTY in its list of modes and
in its manual, and uses the name only to say where the mode comes
from. If you would like that worded differently, please tell me and I
will change it.
My two questions:
1. Do you welcome independent implementations of JTTY, and on which
terms? For FT4 and FT8 your 2020 QEX paper sets the terms out. We have
found nothing comparable for JTTY yet, and we would like to follow
whatever you ask.
2. Would you consider completing section 20.3.3 of the User Guide,
which today reads "(… more to be added …)"? Independent implementers
take the sync word, the generator polynomials, the CRC and the
modulation details from third-party write-ups. An official description
would help keep every implementation compatible as the mode develops.
And a small one: if the over-the-air format may still change before
the general release, is wsjt-devel the right place to watch for it?
Thank you for JTTY, and for everything the WSJT team has given the hobby.
73,
de Yousuf AL Balushi / A41UX / 73
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