(Araucaria) Brasil - Africa em VHF (2M).

[DXer]

OK...O K1JT adicionou mais informacoes sobre esse QSO.

=================================

Dear Pieter V51PJ,

I do not in any way wish to throw cold water on your attempts at
trans-Atlantic communication on 2 meters, but I would like to be sure
you understand what has been accomplished.

Evidently you are using an unreleased version of WSJT-X built from the
development branch of our open source code. The QRA64 mode there is
functional but not yet yet fully complete, and some details of its use
are not yet documented.

Apparently both lines of decoded text shown in the screen shots I've
seen are flagged with the number "8" at the end of line. This indicator
shows how much "a priori" information (if any) has been used as part of
the decoding procedure.

In case it would be useful, here is some (internal) documentation from
our source code describing the end-of-line return codes from the QRA64
decoder:

/*
Return codes:
-16 Failed sanity check
-2 Decoded, but CRC check failed
-1 No decode
0 [? ? ?] AP0 (decoding with no a-priori information)
1 [CQ ? ?] AP27
2 [CQ ? ] AP42
3 [CALL ? ?] AP29
4 [CALL ? ] AP44
5 [CALL CALL ?] AP57
6 [? CALL ?] AP29
7 [? CALL ] AP44
8 [CALL CALL G] AP72
*/

The information here is rather cryptic, intended for our own programming
use. But in short, the "8" flag means that the content of your
transmissions could be determined (and verified with the transmitted
message's cyclic redundancy check) only because its plausible content --
in this case, two callsigns and a grid locator -- were known in advance
to the receiving software. (Of course, this known information is always
available for a scheduled QSO attempt.)

For our weak-signal software development we have been using the
following somewhat "official" definition of a minimum valid QSO, which
appears in the IARU Region 1 VHF Managers Handbook:
#########################################################################
7.1 Minimum Requirement for a valid QSO (Vienna 2007)

A definition for a valid QSO on VHF and on higher bands is:

A valid contact is one where both operators during the contact have

(1) mutually identified each other

(2) received a report, and

(3) received a confirmation of the successful identification and the
reception of the report.

It is emphasized that the responsibility always lies with the operator
for the integrity of the contact.
#########################################################################

It seems to me that your exchanges with PY1MHZ have satisfied item #1 in
the above list. Now, you need to persist and exchange some previously
*unknown* information, such as a signal report, followed by an
acknowledgment -- and then you will have made a truly record-breaking QSO!

In passing, I should also caution you and others not to take the dB
signal reports produced by our existing code too seriously. At the low
end of the S/N range for marginal signals, say below -28 dB for QRA64,
the uncertainty of S/N estimates gets very large.

-- 73, Joe, K1JT

On 2016-10-05 7:13 PM, DXer wrote:
> Saiu na lista do WSJT. Eu nao tenho familiaridade com VHF, mas isso
> parece ser um senhor resultado. Parabens ao PY1MHZ.
>
> Eu ja tinha lido sobre os preparativos que ele estava fazendo para
> tentar esse feito.
>
> 73 de Vince, VA3VF
>
> ================================================================
>
>
> tonight i want to congratulate the software team for giving us the
> software digital mode QRA64
> tonight history was made using this software in the first 2m contact
> across the atlantic
> history was made but without the time and effort put in by you guys this
> could never happened
> first contact was made at 2038 when py1mhz decoded my signal at -37dB
> level at his qth
> at 0028 his signal was decoded at v51pj qth at -36dB
> thans to you guys for being part of this histric moment
> we will keep on testing and pushing everything to the limit and further
>
> congratulations team
>
>
> de v51pj