Modified JT65 Replies

WSJT 65 (and variants) Discussion

Modified JT65 Replies

Postby VK2FAK » Fri Jun 06, 2014 4:32 pm

Hi all...

I have noticed this week of a new change going on by some people.....In recent times some were combining the RRR with the 73 ..

but now it seems some don't want to send the full callsign after the first time......instead using the last 3 characters of the call.. as in FAK WDM 73 , as a not real example....

This is going a bit far I would think...

John
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Re: modified JT65 replies

Postby VK2PR » Fri Jun 06, 2014 4:41 pm

Haven't seen that myself John, but yeah, that's pretty poor.
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Re: modified JT65 replies

Postby VK3HZ » Fri Jun 06, 2014 9:23 pm

It's worse than that.

If you use the standard message formats, WSJT will encode the message and the other end can apply Deep Search to dig it out of the noise.
If you just type in any old thing, the program sends it as plain text and you lose quite a margin of performance.

So, no only is it lazy, it's actually a dumb thing to do!

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Re: modified JT65 replies

Postby VK4WDM » Fri Jun 06, 2014 9:49 pm

I have noticed the same thing. Not only is it poor operating it is almost certainly illegal to use partial call signs. Just because it is data and not phone or CW it does not mean that the regs can be disregarded.

I sometimes shorten the sequence and just send a report rather than "XXXX VK4WDM QH30" if I think that a station needs to know that they are getting out OK.

73

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Re: Modified JT65 Replies

Postby VK4OX » Sat Jun 07, 2014 6:55 am

VK3HZ wrote :It's worse than that.

If you use the standard message formats, WSJT will encode the message and the other end can apply Deep Search to dig it out of the noise.
If you just type in any old thing, the program sends it as plain text and you lose quite a margin of performance.

So, no only is it lazy, it's actually a dumb thing to do!


Hi David,
Correct me if I'm wrong but doesn't Deep Search "dig" the callsign out of a Data Base, NOT the noise on the radio channel?

73, Adrian. VK4OX.
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Re: Modified JT65 Replies

Postby VK3HZ » Sat Jun 07, 2014 8:30 am

Hi Adrian,
VK4OX wrote:Correct me if I'm wrong but doesn't Deep Search "dig" the callsign out of a Data Base, NOT the noise on the radio channel?

I missed the :wink: on your message but the answer is obviously "No".

Even without Deep Search, you get coding gain by using the standard format rather than "free text". With Deep Search enabled, you get the additional benefit of correlation against a database of known active callsigns - just as people do mentally when operating other modes like CW. However, if it's only noise, there's no result.

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Re: Modified JT65 Replies

Postby VK4OX » Sat Jun 07, 2014 10:03 am

To: VK3HZ
Hi David,

I think we both know where this is leading...

The only thing obvious is that if there is only noise there is no result.

Computers using a Data Base to provide a correlation and then a "decision" are using "prior knowledge". It's just my opinion, but operators using a "human brain" as a decoding device should, (must?), divest themselves of their prior knowledge and use only the data transmitted over the radio path to make decisions as to the validity of a contact. Personally, I make real time audio recordings of all my "noteworthy" cw/ssb contacts. If another, competent Operator, with NO prior knowledge could not validate the received data with his brain, then I would not consider the contact to be valid.

The premise that because human operators use prior knowledge to validate contacts makes it okay for computers to do the same is, in my view, false.

73, Adrian. VK4OX.
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Re: Modified JT65 Replies

Postby VK3HZ » Sat Jun 07, 2014 2:44 pm

Hi Adrian,

What's good for the human is not good for the computer?

Anyway, this matter has been heatedly debated at great length by many without any conclusion so I see no point in re-opening the matter.

I think we'll just have to agree to disagree.

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Re: Modified JT65 Replies

Postby VK4OX » Sat Jun 07, 2014 3:23 pm

Hi again David,

Agreed.

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