[CQ-Contest] Impressive demonstration of one dB of signal strength improvement
Bob Shohet, KQ2M
kq2m at kq2m.com
Wed Aug 21 19:58:01 EDT 2019
That’s Interesting Bernie. For me it is dependent on how well I can hear them. If they are strong enough for me to hear them reasonably well, then when I am dealing with heavy qrn with brief short bursts of relative quiet, (I think of it similar to meteor scatter) – you have maybe 2 seconds to get the call – faster is better; at higher speed you might get the whole call in one shot vs.with slower sending, fighting to get one letter or two repeatedly over perhaps a full minute or longer, or losing the station in qsb. However, if they are weak and there is heavy qsb and/or qrn, then I agree with you that slower is usually better – more time to hear each individual character.
Sometimes if I am calling a DX station in high qrn cndx and they are reasonably loud, I will alternate the speeds in my calling for that reason, especially if I know the opr can copy cw at higher speeds. I don’t know what the qrn sounds like on the other side but if there are brief windows in time between static crashes and they can hear a KQ2 calling, then at 35 wpm they likely already have my call; at 18 wpm they likely won’t.
From: Bernie McClenny, W3UR
Sent: Wednesday, August 21, 2019 6:11 PM
To: KQ2M Bob Shohet
Cc: W3LPL Frank Donovan ; CQ Contest
Subject: Re: [CQ-Contest] Impressive demonstration of one dB of signal strength improvement
For me, and I suspect for many other Topband ops, when QRN/QRM is involved slower is better than faster! 18-20 WPM is about the right speed.
Bernie McClenny, W3UR
Editor of: The Daily DX (1997-2019)
The Weekly DX (2001-2019)
How's DX? (1999-2019)
Two week trial -
> On Aug 21, 2019, at 4:26 PM, Bob Shohet, KQ2M <kq2m at kq2m.com> wrote:
> I have never had the opportunity before to hear differences in signal strength by 1 db increments. +1 db is clearly an advantage and a +2 db difference nearly obliterates the weaker signal. Remarkable. I wish I had heard this 20 years ago! ;-)
> The differences in copy between different CW speeds is very interesting too. I suspect that most contest ops will generally do better with the higher speeds unless they are exhausted to the point of mental impairment, in which case the slower speeds might work better.
> Thanks for posting this Frank and a special thanks to AB7E for creating these audio recordings with explanations!
> Bob, KQ2M
> From: donovanf at starpower.net
> Sent: Wednesday, August 21, 2019 11:15 AM
> To: cq-contest at contesting.com
> Subject: [CQ-Contest] Impressive demonstration of one dB of signal strength improvement
> These recordings are an impressive demonstration of the benefit of
> one dB of signal strength improvement in a weak signal situation.
> Click on the links on this website:
> ----- Original Message -----
> From: "David Gilbert" <xdavid at cis-broadband.com>
> To: elecraft at mailman.qth.net
> Sent: Wednesday, August 21, 2019 7:02:21 AM
> Subject: Re: [Elecraft] KPA500 Coax size requirements
> That's not a universally true statement.
> Several years ago I was trying to decide which antenna to buy, and my
> choice came down to two antennas that were 2 db apart. I created some
> audio files by recording typical band noise and then overlaying them
> with recorded CW messages at various strengths. The difference between
> 1 dB above the noise level and 2 dB above the noise level can make the
> difference between no copy and copy. The files and testing methodology
> can be found here:
> If you're ragchewing it doesn't matter, but if you're trying to make a
> contact and your signal is at the level of the mud it does.
> Dave AB7E
> On 8/20/2019 9:18 PM, Jim Danehy wrote:
>> ONE DB loss is the LEAST DETECTABLE amount a human can detect. Hardly if not impossible to notice.
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