[DSP-10] Something I don't understand about Alt/A box in LTI mode.

[Courtney Duncan]

I'm looking at the N6NB beacon which is coming in pretty well 
tonight.  I have Te set to 600K, the noise floor in the main spectral 
display is about 10, and the beacon, on peaks, is about 20 which it 
says is -140 dBm.  Sampling is 9.4 Hz. so this all more or less adds 
up given Boltzman's Constant, -198.6 dB-Hz / K.

In the LTI Alt/A box, it says about 1000 points, 15.0 dB.  Same Te. 
Cntr Sig = -155.9 which is 6.4 dB (S+N)/N.  This agrees with the 
yellow line.

How is the Cntr Sig value calculated and what does it mean?

Courtney, n5bf/6