Re: Mystery JT65 signal

Patrick Lindecker

Hello Andy,


If KVASD (soft decoder) is ON, extract it to OFF. This decoder is very sensitive but introduce false decodes. The standard “hard decoder” has not this problem (although a false decode is still possible but very rare).





De : [] De la part de Andrew OBrien
Envoyé : vendredi 10 avril 2020 15:08
À :
Objet : [digital-mode-radio] Mystery JT65 signal


Fron a ham on my WSJTX group.
Andy K3UK



Hi everyone,

I struggle identifying a mysterious JT65 signal on the
30m band. I already asked this in other groups but no solution so far.

A few weeks ago I stumbled on a regular JT65 transmission on 10140.7kHz
transmitting every third minute. The message does not seem like coming
from ham, no callsigns but a cryptic string of characters, see this
short log excerpt:

20200408_1402 -21 -0.6  763 # KJIVVFULMOAI              .
20200408_1411 -21 -0.6  764 # KJIVMFULMQ00              .
20200408_1417 -21 -0.6  764 # KJIVMFULMQ05              .
20200408_1420 -23 -0.6  764 # KJIVKFULMQB0              .
20200408_1426 -19 -0.6  764 # KJIVDFULMR00              .
20200408_1429 -24 -0.6  764 # KJIVMFULMQAG              .
20200408_1505 -23 -0.6  765 # KJIVJFULMP00              .
20200408_1535 -21 -0.6  764 # KJIVJFULMP95              .
20200408_1541 -25 -0.6  764 # KJIVLFULMP00              .
20200408_1547 -22 -0.6  764 # KJIVKFULMP7F              .
20200408_1550 -26 -0.5  764 # KJIVQFULMO9H              .

This signal appears to be JT65, at least it can be decoded as one and
transmits every 3 minutes. Looks like a beacon or similar.

What we know so far, not in any particular order of importance:

- freq: 10140kHz +700Hz USB
- transmits 7/24 every third minute
- correct JT65 coding, can be decoded using WSJT-X or JTDX
- the message shows a pattern of


where capitals are always the same while at places x varying

- carefully examining condx, appearing/disappearing of the sig,
coincidences to FT8 sigs shows probable location somewhere in AS Russia,
East EU, or maybe North EU, although at his stage needs further
listening, collecting of data and evaluation to narrow possible area

See a screenshot attached from yesterday evening. Yet a few wav files
can be downloaded as 9A5CW Patrick recorded two days ago:

I am curious to know if anyone else also noticed this transmission, has
additional details or willing to help me spotting the source.

Thank you, 73...  Sanyi, HA3PG

Avast logo

L'absence de virus dans ce courrier électronique a été vérifiée par le logiciel antivirus Avast.

Join to automatically receive all group messages.