[Moon] WSJT/CW

Sun Apr 20 13:26:25 CEST 2008

Dominique,

You have nothing to offer but polemics, personal attacks (no, not versus me
yet) and zero knowledge about how DS works.

Full Stop. Expect no further reply whatever you should write now...with you
it sadly does not make any sense.

Bernd

-----Original Message-----
From: Dominique Fässler / HB9BBD [mailto:dfaessler at bluewin.ch] 
Sent: Sonntag, 20. April 2008 13:11
To: 'DF2ZC'; moon at moonbounce.info
Subject: AW: [Moon] WSJT/CW

Bernd
"(1)
JT65 does communicate everything via the air."

Wrong. You know that and it will not become less wrong by repeating.

That is why I am not involved and separation between make and fake is
ultimate. I am not involved in your computer science and I will not.
73 HB9BBD
Dominique

-----Ursprüngliche Nachricht-----
Von: moon-bounces at moonbounce.info [mailto:moon-bounces at moonbounce.info] Im
Auftrag von DF2ZC
Gesendet: Sonntag, 20. April 2008 12:44
An: moon at moonbounce.info
Betreff: Re: [Moon] WSJT/CW

Dear Hakan and all,

Just for clarification:

(1)
JT65 does communicate everything via the air.

(2)
In JT65 DS the callsigns, i.e. "SM7WSJ DF2ZC", you are looking for are
detected by means of correlation (mathematically comparing the weak signal
in the noise with signal forms constructed by the help of the call3.txt
database). Of course the information you are looking for is already present
on your hard disk, though "SM7WSJ DF2ZC" is transmitted and received over
the air. The only previously unknown information you gather is that the weak
signal indeed is one of the constructions with the help of call3.txt, so one
of the some 1000 combinations. This equals ld (1000) = some 10 information
bits. The amount of information gathered roughly is as high as it is when
you receive two arbitrary alphanumerical characters, such "A7" for instance
as the ld (36*36) = 10,34 bit. If it were 8000 possible combinations, it
would equal some 13 information bits, with 16000 possible combinations it
would equal some 14 information bits, with 64000 combinations some 16
information bits. So with increasing the call3.txt database the information
bits of a DS decode rise.

However, everything is still transmitted over the air! Only, the information
you gather is that the weak signal in the noise is one of the callsign
contructions with the help of call3.txt or not, so one of the roughly 1000
possibilities. This correlation is a well established mathematical procedure
used, similar to a "matched filter" which only delivers the output one is
looking for (if that signal is indeed present on the receiver) or nothing at
all. Again: The information gathered is "Yes, it is one of the 1000
callsigns." - or as DJ5HG calls it: an index.

This is very much similar to the well aknowledged (and never discussed!!!)
sked gain on CW of some 3 dB, or to the fact that when you are called by a
weak station you nearly always copy your own callsign better than the
caller's callsign. That is what I meant with the memory between the ears. It
is always easier to copy "SM7WSJ DF2ZC" in a CW sked at a marginal signal
strength than on random an arbitrary combination such as "SM7WSJ AZ4GOR". We
all know that for decades and never put in in question.

BTW This means in a sked (CW and JT65 as well) your personal call3.txt is
just one callsign, "DF2ZC". Therefore you gain only ld (1) information,
which equals 0 information bits! This applies also if you'd copy me with
599, the amount of information bits cannot be increased because "DF2ZC" is
already present on your personal hard disk in the head. Actually, you gain
not 0 but 1 bit of information: You now know that DF2ZC is really there for
the sked which is the only thing you did not know in advance.

Actually the underlying information theory is even a little more complicated
as the amount of information gathered is related to likeliness. When a
rather active station such as W5UN, KB8RQ or S52LM is copied the information
content is less than for instance when SV1BTR is copied calling you on JT65
;-)
I'll leave that out to make understanding easier and assume all callsigns
are equally likely.

(3)
If you understood (2) correctly you will easily see that unlike some guys
permanently try to make us believe JT65DS does not communicate only two
letters of both callsigns via the air to have a decode and the rest of the
callsigns is added with the help of call3.txt. That is rubbish! Those guys
such as HB9..., SM2...and others do apparently not have the slightest clue
how DS works. Yet, that does not keep them from repeating incorrect
statements.

(4)
IMPORTANT! I did not and I will never say that this means that people using
CW don't receive all characters of a callsign!!! Whoever accuses me of doing
so does not at all understand what I'm saying. I repeat: I confirm all CW
friends always copy all dits and dahs in a QSO!!! This has no influence on
what I'm saying above. 
Sadly, there are some guys who are not serious with the QSO rules, but in
both modes. The cheat on themselves at the end. Also I do not say it is
acceptable if people exchange QSO details on chat/telephone etc before the
QSO is complete. I regard a chat as a online contact room to solicitate
short notice skeds.

I do not intend to go on replying replies to this post in public. Should you
(or anyone else) have any further questions I'm happy to discuss that with
you in private emails and leave this off the reflector.

vy 73 Bernd DF2ZC (JO30RN)
www.df2zc.de

____________________________________________
144 MHz EME NewsLetter:
www.df2zc.de/newsletter

144 MHz DXCC #21
144 MHz WAC

Kenwood TS 2000
2 x GU74b by LZ2US
4 x 2M18XXX 21 dBd full elevation

-----Original Message-----
From: moon-bounces at moonbounce.info [mailto:moon-bounces at moonbounce.info] On
Behalf Of Håkan Harrysson
Sent: Sonntag, 20. April 2008 09:14
To: moon at moonbounce.info
Subject: Re: [Moon] WSJT/CW

Hello again,

I see some try to turn this into that it shall exchange unique numbers or
even a try to see what mode does it best.

For me this have nothing to do with this at all.

I was very interested to work new DX on 144 and was up for every nights sked
back in the SKD file days. The expeditions back then was very impressive
(They are also today reading Bobs Etiopia travel.).

I work new DXCC using CW SSB FSK441 and was starting to use JT44 and then
JT65.   When i realized that i did not comunicate full calls over the air
using deep search i stopped hunting DX and i also lost a very big interest
in the hobby.

I dont question the deep search accuracy as i always feel i decode the right
things on air. The problem is that i feel it gets information from the Call
3 file or what i put in the CALL field and not from the radiopath.

I refuse to work new one without both callsigns exchanged over the air even
that Bernd suggests that we already  have that information between the ears
so it does not matter.  For me it does matter even if i can tell who many of
the EME:r are on their keying. I always wait untill i have heard full calls.

Point is that i want  both calls and report over the air in any mode to have
a complete contact, As i have understood i dont have that using deep search
JT65.

TNX to all for a good polite discussion without any strange moderation.

73 Hakan  SM7WSJ

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