S units are a logarithmic scale and you don't use the ratio of S units
for signal to noise. If both the signal and the noise are reduced by 3
S Units, which is 18 db, the actual signal to noise ratio stays exactly
the same.
Beverages are often quieter because they don't hear equally in all
directions. If the noise happens to be in a different direction than
the signal and the noise is in an unfavorable direction for the
beverage, then the signal to noise is improved.
Carl Moreschi N4PY
58 Hogwood Rd
Louisburg, NC 27549
www.n4py.com
On 9/9/2014 7:53 PM, Richards wrote:
On 9/9/2014 4:51 PM, Carter wrote:
If the *noise* is "noticeable[y] quieter, 1 to 2 S units", wouldn't
the wanted *signal* also be down 1 to 2 S units?
___________________________________________________
Hi Carter --
I liked you question, and ponder... suggest... er... just thinking out
loud...
I wonder if the important or operative concept is "signal-to-noise"
ratio. Consider Beverage antennas. They have much weaker signals, but
also much lower noise factors, and make great receiving antennas. I
suspect (i.e., guess) some thing similar is happening in Bob's case.
A tentative theory: (i.e., wild guess) = If BOTH signal and noise are
reduced, then the resulting signal seems stronger compared to the noise.
Say, you have a signal level of of 8 S-units and a noise factor of 5
S-units, then you have a ratio of 1.6; but lowering each by three
S-units, assuming some sort of linearity between the two, you get a
ratio of 2.5, so the signal level seems stronger relative to noise level.
OK, Maybe it just seems that way. I am sure there is a mathematical or
electrical fallacy lurking in the weeds, and I recall Jim Brown trying
to explain a similar fallacy regarding the effects of the RF-GAIIN
control... which I am still trying to wrap my head around... But I have
not forgotten it... so, at least it SEEMS OR APPEARS to have a better
signal to noise ratio, (remember the Beverage antenna seems to work this
way) and that would be an advantage.
OK... just a stab in the dark, the usual disclaimers apply.
------------------ K8JHR
------------------------------------------------------
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