Patent ID: 6509728
Filing Date: 2003-01-21
Classification: G01R,G06F,H03K

Abstract:
A spectrum analyzer comprising:signal receiving and processing means for receiving an input signal in accordance with desired frequency sweep information; sampling means for sampling an output signal output from said signal receiving and processing means in accordance with a plurality of threshold values and outputting a plurality of output codes corresponding to sample values of an envelope of said input signal; histogram measuring means for measuring a group of histograms corresponding to said output codes output from said sampling means; arithmetic means for calculating an amplitude probability distribution of said output signal based on said histogram group measured by said histogram measuring means and said desired frequency sweep information, and classifying said amplitude probability distribution into a group of bands having a plurality of ranges corresponding to said histogram group; and display means for displaying said bands having said ranges calculated by said arithmetic means as an area for display in different states; wherein said arithmetic means includes: (i) means for calculating a functional scale of said amplitude probability distribution in such a manner that, when said input signal is thermal noise according to a Rayleigh distribution, points corresponding to components of the thermal noise are plotted in line, and (ii) means for interpolating intermediate points between said plotted points; and wherein said display means displays said band group having the plurality of the ranges as an area in different states and the functional scale of the band group having the plurality of the ranges, and further displays a functional scale graph on which the points corresponding to the components of the thermal noise are plotted in line with a horizontal axis of the graph representing time ratios and a vertical axis representing amplitudes.