Re: RS Yesterday

Arie Dogterom <pa0ez@...>

Hello Sam,
I have been involved in that IARU R1 definition ( it was accepted at the Brighton conference almost 40 years ago) and the text is based on a proposal from PA0MS and me.
At that time there were no commercial VHF-up receivers. The standard was a convertor in front of a 28 of even 4 MHz RX. That is the pure reason for the 20 dB difference between the HF and the VHF-up reference.
One can fight about an S-point being 6dB or something else. If people are using a reasonably calibrated meter than it is worth contemplating. At the time we tought that the dBm values and the 6 dB were a reasonable approach to the existing (ARRL?) system with terms as "very strong" etc. I do not think many people do in fact know what the "non-dBm" definition of S-points are.
I can agree to any deviation of the -93 dBm reference and/or 6 dB step, if that could result in real reporting. But I am rather pessimistic.

----- Original Message -----
Sent: Tuesday, May 26, 2009 3:15 PM
Subject: Re: [ukmicrowaves] RS Yesterday

I know Ari. You have long campaigned for a sensible system.
But I think the definition of VHF/Microwave S9 is set far too high for the reasons I gave in my column and DUBUS.

By any current, common, usage Gerd was 59S here yesterday. Yet by IARU definition he was considerably short of S9? I don't think I am wrong to send S9 if I believe that to be correct and what is expected, but the existing system is clearly unreliable as any sort of meaningful measurement of levels. A range of maybe 20 to 30dB is outrageous.
It was created  based on equipment standards of too many years ago. They need updating, IMHO.
System noise figures of 10 and 20dB, at VHF, belong in the past! A system based on those sorts of equipment sensitivities needs looking at again, surely?

73 de Sam, G4DDK

Flack jacket on.....................

From: Arie Dogterom nl>
Sent: Tuesday, 26 May, 2009 1:58:23 PM
Subject: Re: [ukmicrowaves] RS Yesterday

Hello Sam,
It is not the s-scale but the people giving reports out of their black hat. I am always worrying about my rx when reveiving s9 from stations I cannot give more than s4
----- Original Message -----
From: Sam
Sent: Tuesday, May 26, 2009 2:48 PM
Subject: Re: [ukmicrowaves] RS Yesterday

I tried my technique of level measurement on DJ5BVs strong RS signal. He measured up to -112dBm, although a little peak energy will have been lost in the Doppler sidebands.
This is interesting as Gerd was getting so many 59s reports. This equates to about 19dB below an IARU definition of S9!

I'm not raising this as any sort of issue but merely illustrating how misleading the current 'S' system can be!

2 new squares on 3cm. I love the rain!

And 2 new squares (and initials) on 13cm EME this morning.

73 de Sam

Not sent from my PC!

On 26 May 2009, at 12:35, "G3XDY" <g3xdy@btinternet. com> wrote:

One thing I noted in yesterday evening's good RS opening was the way that
dog-leg paths that normally don't seem to work were possible. I heard DJ5BV
(JO30) consistently on a heading of about 165 degrees, he would have been
beaming south of West so the path had a near right angle reflection,
similarly F6APE in IN97 (west south west of the scatter point) was worked on
the same heading. I also had a good backscatter contact with Neil G4BRK.
Signals were not huge, indicating that the losses were higher than on the
more direct paths, but it demonstrates that RS will work over significant
distances in any direction if the storm is sufficiently intense, regardless
of the path geometry.


John G3XDY

------------ --------- --------- ------

Yahoo! Groups Links

Join to automatically receive all group messages.