On Mon, 18 Sep 2006 03:27:46 GMT, Owen Duffy wrote:


The industry uses a single metric for fully capture the receive
performance of the entire station, it is the Gain to Noise Temperature
ratio, written as G/T. S/N is directly related to G/T, for every one
dB improvement in G/T, you get exactly 1dB improvement in G/T.

Prophetic! Should have read:

The industry uses a single metric to fully capture the receive
performance of the entire station, it is the Gain to Noise Temperature
ratio, written as G/T. S/N is directly related to G/T, for every one
dB improvement in G/T, you get exactly 1dB improvement in S/N.

As you know from HF, changing the NF of your receiver (by swithing in
the attenuator or turning the preamp off) often does not change the
S/N ratio of signals on the lower bands where ambient noise dominates
system performance. G/T gives you a method of predicting what S/N
improvment you will achieve with each of your proposed preamps (model
each at top or mast of at the tx, change out the coax for better stuff
etc)... and when you assess the cost of the improvement, you might
have different thoughts about what is "best" for you.

Owen
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