>
>> However, if the signal was at or near the noise level, then 2 db
>> increase could make the signal more easily read. A 2db increase is
>> like Christmas to someone using a single yagi for moonbounce.
>
>Even 1dB is a huge increase when copying a signal near noise.
>The error rate changes considerably here when working CW, when
>I pick antennas that offer even 1dB more S/N ratio.
>
>Most S meters are in the area of a dB or two at the low end of the
>S scale, expanding as they get up around S-9 and they work fairly
>well from that point on. My ICOM's are that was, as is my Yaesu
>stuff. Almost no receivers are 6dB, most are 3 to 5 at the middle
>scale. Most receivers actually tried for 5 dB per S unit, not 6. But
>of course the calibration is often all over the place in different scale
>areas, being much fewer dB per S unit at the low end.
>
>Because we often see a 1 S unit change when it is only 2dB or so,
>we often don't realize how much a dB or two actually means on
>weak signals.
>
>That's also why so many antennas have "supergain" or super F/B
>on the air. Because people just assume an S unit is 6dB.
>
// At one time, an S-unit increase was defined as a doubling of received
voltage -- i.e., a 6db increase.
- R. L. Measures, 805.386.3734,AG6K, www.vcnet.com/measures.
end
--
FAQ on WWW: http://www.contesting.com/FAQ/amps
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
|