From: "Mike Dennison" <mike.dennison@rsgb.org.uk>
Organization: Radio Society of Great Britain
To: rsgb_lf_group@blacksheep.org
Date: Mon, 24 May 1999 17:41:10 +0100
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Subject: LF: Spectrogram dot length
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Reply-To: rsgb_lf_group@blacksheep.org

In bench tests it has been claimed that there is no advantage in 
going for a dot length exceeding 3 or 4 seconds when using QRSS 
and Spectrogram.

During a QRSs QSO this weekend with DJ5BV, local interference 
came on at S9 blanketing the screen with 'snow'. DJ5BV had been 
a very clear, but inaudible signal previously and it is a tribute to this 
technique that I could complete the contact with an inaudible 
station despite S9 QRM. However it was a great struggle and relied 
largely on me knowing that there were only a few possible things 
he could have been sending. (The old 160m tricks come in useful).

What is interesting is that his dashes at about 9 seconds long 
were much more readable that his dots as they stood out from the 
noise. Most of the final over was read using just the dashes!!

This makes two points:
1) What a good idea it was to have reports using just dashes.
2) There does appear to be an advantage in a practical situation 
when dot lengths are increased to 10s or so.

On the subject of QRSs, it may be useful to list a few abbreviations 
which are acceptable. For instance, DJ5BV did not send QRZ? to 
me, he just sent ?? which was clearly understood. A replacement 
for 73 would be useful - what about just TU (meaning 'thank you' for 
anyone who hasn't done HF CW recently)?

Mike, G3XDV (IO91VT)
http://www.dennison.demon.co.uk/activity.htm