http://elecraft.85.s1.nabble.com/150-watt-boots-for-160m-tp4151943p4172612.html
being written in two languages, e.g. just barely copiable (by at least
> There was an interesting series of low power beacon receiving tests
> conducted in December 2004 through January 2005 by N2XE. John sent a beacon
> ID message including a unique code word at various power levels on 80m over
> a several day period. You had to correctly copy each code word correctly to
> verify reception. There's a lot of documentation on the Topband and QRP-L
> lists over that period, but here's a brief summary of the results:
>
> 80 uW - 8 stations correctly copied.
> 40 uW - 1 station
> 27 uW - 1 station
> 20 uW - 0 stations.
>
> The power difference in dB at each succeeding lower level was (top to
> bottom):
>
> -3 dB (i.e. the 80 uW to 40 uW test)
> -1.7 dB
> -1.3 dB
>
> I copied the beacon at both the 40 uW and 27 uW levels but could not
> decipher the code word at 20 uW even though I could detect presence of the
> signal. Unfortunately N2XE ran 20 uW only briefly (because at that point
> nobody else was hearing it). I believe I could have copied it if he had run
> it as long as he ran the other tests.
>
> The point of this is that small changes in dB do indeed make a difference in
> the ear/brain's ability to **copy** weak signals in noise, which is really
> what the discussion is about. Tom W8JI added the following interesting
> observation (which I also noticed and agree with):
>
> "Now for the curious effect I observed.
>
> While I didn't spend a large amount of time listening to 80
> and I never listened to 40 at all, I did notice one thing
> that I found interesting. Listening to the very low power
> transmissions on 80 meters I observed a very pronounced
> signal peak just before sunrise. The effect was very much
> like the effect called "search light" or "spot light"
> propagation. While the signal was largely in the noise and
> unreadable from 0900 Z until 1120 Z, I observed a very
> clear "strong" peak between 1125 and 1135 Z where the signal
> was the equivalent of about a "559" or better DX report. By
> 1138 copy was back to nil with an increase that provided a
> short 2 minute long readable signal starting at 1143 Z .
> After 1145 Z that was it for the signal. I never really
> noticed this effect over the same path when power levels
> were higher and signal levels stronger, although I'm sure
> the path loss went through similar variations. This is why
> even one dB sounds like a large change when signals are in
> the noise, and is meaningless with "579" signals."
>
>
http://lists.contesting.com/archives//html/Topband/2005-01/msg00023.html>
> 73, Bill
>
>
>
> --
> View this message in context:
http://n2.nabble.com/150-watt-boots-for-160m-tp4151943p4172347.html> Sent from the [K3] mailing list archive at Nabble.com.
> ______________________________________________________________
> Elecraft mailing list
> Home:
http://mailman.qth.net/mailman/listinfo/elecraft> Help:
http://mailman.qth.net/mmfaq.htm> Post: mailto:
[hidden email]
>
> This list hosted by:
http://www.qsl.net> Please help support this email list:
http://www.qsl.net/donate.html>