How to set sweep time of speatrum analyzer?

Hi all,
How to set sweep time of speatrum analyzer to get the correct result?If set the time too fast,get lower power.I get a n equation:BW^2/K,BW----RBW,andi do not know K=?,and why?
Thanks,

Spectrum analyzers usually have an "auto sweep time" mode where it automatically selects the proper sweep time depending on your specified resolution bandwidth and video bandwidth.

K depends on the characteristics of the particular filter used in the instrument. Here's a quote from Agilent Application Note 150, "Spectrum Analysis Basics:
"The value of k is in the 2 to 3 range for the synchronously-tuned, near-Gaussian filters used in many Agilent analyzers."

Here is the entire app note, 5952-0292EN.pdf, about 8.5 megabytes:
http://www.home.agilent.com/agilent/...LENT_EDITORIAL