[TowerTalk] 5 db required to see?

[Tom Rauch]

> Repeat after me ... "all other things being equal..."  But Tom's point is
> a good one, of course -- there are a lot of factors that go into a contest
> success, however one defines that.  I don't doubt that each of the factors
> he mentions could be more important to the outcome than whether your
> system has 1 dB more or less gain.  Some you can do something about, and
> some you can't.  The 1 dB gain can be found, at a price. 

One dB gain can actually HURT the watts-per-listener total at the 
other end, if it comes at the expense of radiation pattern width.

To work this problem correctly, you would have to maximize the 
improvement at the largest number of listeners who are receiving a 
marginal signal. The problem is more likely where you have nulls, 
rather than the absolute strength of the main lobe in the peak of the 
main lobe.    

 So can a 1 dB
> better signal-to-noise ratio.

One dB more antenna gain does not translate into one dB 
improvement on receiving, unless the noise is evenly distributed all 
around the antenna or unless the receiver system is limited by 
internal noise...rather than external noise.

Actually, one dB gain improvement can degrade the number of 
stations you work if it comes at the expense of pattern width. You 
may well remove signals from an area outside of the main lobe.

It's true that, pattern shape being the same, that 3 dB more FS will 
help. But if that 3 dB more FS comes at the expense of cutting 
pattern width in half, you could easily DECREASE the number of 
contacts you make.

Broadcast stations, trying to get the maximum number of listeners 
per kilowatt transmitter power, are always careful to not reduce FS 
over the more populated areas. It's foolish to worry exclusively 
about "bombing" one narrow target area instead of what the overall 
pattern looks like, and where your listeners are. What I'd want is a 
big fat lobe that covers all of the target area with nearly equal signal 
and no useless areas.

ATT had a different goal, when international telephone was over HF 
links.




73, Tom W8JI
w8ji@contesting.com

--
FAQ on WWW:               http://www.contesting.com/towertalkfaq.html
Submissions:              towertalk@contesting.com
Administrative requests:  towertalk-REQUEST@contesting.com
Problems:                 owner-towertalk@contesting.com
Search:                   http://www.contesting.com/km9p/search.htm