Re: [Amps] 10 DB increase

["Ian White, G3SEK" <G3SEK@ifwtech.co.uk>]

Radioal wrote:
> > > A 10 dB increase in power will be propagated as a 10 dB increase -
> > > regardless of the state of the ionosphere, antennas, locations, etc.
> > ___________________________________________________________
> >
> > If a 10dB increase brings you from zero copy to something above the
> > noise level, that's a near-infinite improvement, wouldn't you say?
> >
> > Much different from going from 20 over 9 to 30 over.
> > --
> > Bill, W6WRT

> No!  An improvement from zero dB to 10 dB is still 10 dB.  It doesn't 
> matter if you went from below the noise to above the noise - it is 
> still 10 dB.
Nobody's disputing that a change of +10dB always *is* a x10 increase in 
signal level. That is a plain technical fact.

But...

> Let's not start equating real numbers to "percent improvement, 
> readability, etc.".

No, let's do *exactly* that... because this whole subject is actually 
about what 10dB - or even 1dB - actually means on the air.

If someone only ever works with S9+ signals that are way above the 
noise, then a change of +/-10dB will mean nothing to them. That's fine, 
but it's only skimming the top surface of what's on the band.

Don't ever forget: "If all the DX is S9, you're missing the REAL DX!"

If your kind of amateur radio means you regularly work DX that is close 
to the noise level, then even 1 dB really can make all the difference 
between success and failure. (I lived on that borderline for 20 years of 
moonbounce, and still visit the area quite regularly.)

Then there are the "statistical" arguments that contesters and DXers 
know about.

Over a 24- or 48-hour contest, if your signal is 10dB stronger it will 
have a large statistical effect on your ability to work stations quickly 
and easily. It cannot be predicted for every individual QSO, but the 
facts emerge very clearly out of large numbers. This can also be a very 
non-linear, threshold-type effect: if your signal is not quite strong 
enough to hold a run frequency comfortably, you will have notably more 
interference and will have to ask for repeats notably more often; and 
other people will have to ask for more repeats from you. All these 
things are cumulative, so below a certain threshold your QSO rate will 
drop alarmingly. This applies particularly to DX QSOs, because you will 
always be weak into your target areas when the band is opening and 
closing, and the DX stations will always have QRM from stations more 
local to them. This really is where every dB counts.

A similar line of argument can be advanced about competing with other 
stations in pileups. Once again 10dB is a huge advantage, and 1dB must 
have a long-term statistical effect.


If these kinds of argument don't apply to your particular style of 
operation, then that's fine. Everyone should be able to enjoy their own 
kind of amateur radio. But don't ever try to tell someone else how much 
10dB is worth to them.



--
73 from Ian G3SEK         'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek
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