[TowerTalk] One DB

[Jim Lux]

At 04:57 PM 5/29/2007, WA3GIN in Alex. City, VA wrote:
>I think your efforts should be rewarded but the test is flawed.
>
>Try using QRP and an attenuator.  Get a distant station to record the two
>transmissions...one with and one without the 1db attenuator in the output.

This too, isn't necessarily a fair test.  It will changed the 
received SNR at the receiver IF the atmospheric noise dominates over 
the receiver noise, so in that sense it's fair as a test of "is a dB 
on Tx worth it".

However, it doesn't address the effects of directivity on receive.. 
increased gain on receive implies smaller beamwidth, which might 
reduce received noise.  As long as the loss in the system isn't so 
much that receiver noise starts to be significant, you could make the 
tradeoff of less antenna efficiency (more loss) in exchange for more 
directivity.

But it's that question of "is 1 dB worth it" that makes this all 
fun.. just because it's somewhat subjective, and not all dBs are the 
same. Rarely are we dealing with nice symmetrical signalling in a 
additive white gaussian noise environment, where you could 
mathematically calculate the effect of a 1dB change.

Jim, W6RMK