Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

donate to eham
   Home   Help Search  
Pages: Prev 1 2 [3]   Go Down
  Print  
Author Topic: What kind of CW signal would 5 db out of noise be  (Read 4300 times)
NI0C
Member

Posts: 2935




Ignore
« Reply #30 on: July 12, 2017, 07:32:25 AM »

Lou,
I still have all the files that AG1LE provided back in 2013.  Each sound file is around 3-4 megabytes.  He provided about 200 five character groups at various s/n ratios from -10 to +8 dB, at 20 wpm and 40 wpm. I can try to email them to you one or two at a time.
73,
Chuck
Logged
VK5EEE
Member

Posts: 1050




Ignore
« Reply #31 on: July 13, 2017, 08:35:04 AM »

Lou,
I still have all the files that AG1LE provided back in 2013.  Each sound file is around 3-4 megabytes.  He provided about 200 five character groups at various s/n ratios from -10 to +8 dB, at 20 wpm and 40 wpm. I can try to email them to you one or two at a time.
73,
Chuck
Thanks Chuck, that'd be great. But my Email has a space problem. Can you try free audio upload site: https://clyp.it/
Logged

Long Live Real Human CW and wishing you many happy CW QSO - 77 - CW Forever

Support CW and join CW clubs. QTT: FIST#1124, HSC#1437, UFT#728, RCWC#982, SKCC#15007, CWOPS#1714, 30CW#1,
NI0C
Member

Posts: 2935




Ignore
« Reply #32 on: July 13, 2017, 12:15:21 PM »

Lou,
I still have all the files that AG1LE provided back in 2013.  Each sound file is around 3-4 megabytes.  He provided about 200 five character groups at various s/n ratios from -10 to +8 dB, at 20 wpm and 40 wpm. I can try to email them to you one or two at a time.
73,
Chuck
Thanks Chuck, that'd be great. But my Email has a space problem. Can you try free audio upload site: https://clyp.it/
Lou, I sent a link to the first file: https://clyp.it/5lp35hih
(expires in 24 hrs), and a key to the random text characters in my e-mail.  Let me know if you want me to generate clips for other signal to noise ratios and/or 40 wpm files that AG1LE produced for us.   
Logged
VK5EEE
Member

Posts: 1050




Ignore
« Reply #33 on: July 13, 2017, 07:18:15 PM »

Very interesting, thanks Chuck!

With -10db and RANDOM groups and 20WPM, results were consistent  for the first 200 characters (I ignored the first two groups, to "tune in" my brain) then I started from group 3 for the next 40 groups. In the first 100 characters I got 11 wrong, and in the second 100 characters I again got 11 wrong.

So my % correct copy was 89% but without repeats which I did on PA0WV -12dB 12WPM test where I got 87% with repeats.

I find that random prevents one from making INFLUENCED guesses as to what was sent when unsure, and instead using rationalization of the timing of CW characters. With PA0WV tests, I WAS I think influenced by some guessing on the English language and that actually IMPEDED me in places -- a traffic handler should not actually guess at words, but CONFIRM anything s/he is less than 100% sure about with a repeat request.

I think I can safely say I can copy 20WPM at -10dB with QRK4 and 12WPM at -12dB at QRK3. I wonder where the real limit is of QRK2?!
Logged

Long Live Real Human CW and wishing you many happy CW QSO - 77 - CW Forever

Support CW and join CW clubs. QTT: FIST#1124, HSC#1437, UFT#728, RCWC#982, SKCC#15007, CWOPS#1714, 30CW#1,
GW3OQK
Member

Posts: 386




Ignore
« Reply #34 on: July 14, 2017, 02:42:46 AM »

Those -10dB code groups are quite pleasant to read because the noise sounds natural to me. I think I was copying 80% as I would have some doubt over a couple of characters in every four groups. Can I see the original text?

Is the conclusion that we can read Morse ok at -5 dB, struggle at -10 and as asked at the beginning, +5 is no trouble at all?

The other skill is to read it when there is a stronger QSO going on a few hundred Hz away which we try to filter out with receiver and brain.
Andrew


Logged
VK5EEE
Member

Posts: 1050




Ignore
« Reply #35 on: July 14, 2017, 08:37:21 AM »

Dear Andrew,

Emailed to you what Chuck sent me, the text for the random groups.

Yes, that is another skill too: filtering a signal when strong QRM is near by!

Maybe someone some day can post one of those to test our skills :-)

I devised a fun weekly event we ran for some months here, called CW Bash. All QSO took place within about 500 Hz or so, it was mayhem, reminiscent to a degree of 500kHz, though the tones all being pure and no MCW (actually one station DID use MCW once or twice, using a Skanti TX) didn't quite reproduce 500kc, which if of course irreproducable!
Logged

Long Live Real Human CW and wishing you many happy CW QSO - 77 - CW Forever

Support CW and join CW clubs. QTT: FIST#1124, HSC#1437, UFT#728, RCWC#982, SKCC#15007, CWOPS#1714, 30CW#1,
K9MHZ
Member

Posts: 1436




Ignore
« Reply #36 on: July 18, 2017, 12:56:22 PM »

Stop being such an ass. You really don't know much because people of actual learning don't behave like you. Sorry, end of discussion. Sad

Sounds like you're giving advice that you could benefit from yourself.  A very interesting snippet was posted over on the the Licensing Forum, specifically in the FCC Loosening their Enforcement Standards thread.  Not very impressive, OM.
« Last Edit: July 18, 2017, 12:58:32 PM by K9MHZ » Logged
VK4FFAB
Member

Posts: 412




Ignore
« Reply #37 on: July 22, 2017, 03:46:00 PM »

Chuck es Lou
same place -10 dB SNR 24 wpm 712 Hz bandlimited flat noise 300-2400 Hz

http://pa0wv.home.xs4all.nl/K1LEM/MINUS10.WAV

cu 30

I can hear the code in there, but without the magic of filters on my radio I cannot make out a single character. The +5 was obviously a walk in the park. Very interesting to read that some can make close to 100% copy something that I would consider to be below the noise and would give up on. Kudo's on the hearing skills to those people.
Logged
Pages: Prev 1 2 [3]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!