ARLA/CLUSTER: Foi falso alarme o contato Transatlântico concluído em 2 metros entre o Brasil e a Namibia

[João Costa > CT1FBF]

Closer Look Reveals that Reported Transatlantic 2 Meter Contact Did Not
Happen

The reported transatlantic 2 meter contact between PY1MHZ in Brazil and
V51PJ in Namibia turned out to be a false alarm, based on an incorrect
interpretation of screen captures from the event — possibly the result of
using an unreleased “development� version of the *WSJT
<http://physics.princeton.edu/pulsar/k1jt/>**-X* protocol’s *QRA64* mode.
As initially reported, extremely weak signals using *QRA64* were received
and decoded on both the African and European ends of the path across the
southern Atlantic. Screen captures of the protocol software were supplied
to document the contact, but the software’s lead developer, Joe Taylor,
K1JT, noticed debugging information, indicating that a prototype version of
the protocol was being used. On closer inspection, the indicator values
showed that the decodes were probably based on call sign information being
known in advance, as is common with scheduled contacts.

“There was no intention to deceive,� Taylor told ARRL. “It was a perfectly
honest mistake. It’s unfortunate. Many of us wish the report of such a QSO
could be true — but it's not.�

Trying to complete a 2 meter contact over such distances is extremely
challenging, and it remains to be accomplished. The Irish Radio
Transmitters Society (IRTS)*Brendan Awards*
<http://www.irts.ie/cgi/st.cgi?brendan>, established to reward the first
transatlantic contact in which one station is in Europe, are as yet
unclaimed. Another false alarm occurred in 2015, when an apparent 2 meter
contact between stations in Newfoundland and Ireland turned out to have
been facilitated by reflections from the International Space Station, which
was in low-Earth orbit above the midpoint of the signal path at the time.

The *WSJT <http://physics.princeton.edu/pulsar/k1jt/>* software suite
includes several digital modes that are designed to work at extremely low
signal-to-noise ratios — such as *JT65*,* JT9*, and *WSPR.* The*QRA64 *mode
—developed by Nico Palermo, IV3NWV, in collaboration with Taylor — has been
incorporated into the *WSJT-X* digital suite The protocol has several
levels of decoding for which it can use previously available information
such as call signs to confirm a match with information from the received
signal. Decoding quality is most robust when no previously available
information is required to make a successful decode.

This appears to simply be an honest error by both stations who deserve
credit for an extraordinary effort and who have pledged to keep trying.

“V51PJ and PY1MHZ have put a big effort into seeing their dream of a
transatlantic 2 meter QSO come true,� Taylor said. “They deserve a lot of
credit for what they have done.�

Pieter Jacobs, V51PJ, said the effort to complete a contact is a work in
progress. “Conditions are ever changing on this long stretch of water, so
we are still trying,� he told ARRL.
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