Crest Factor will fail if it does not meet the mask requirements as specified by ETSI, which specifies that amplitude distribution by means of a tight mask, to give meaning to concepts like "near Gaussian" and "crest factor above 5". This compliance is achieved using an iterative algorithm for calculating the noise sample. This algorithm repeats up to 5 times to try to ensure that the crest factor of the calculated sample is >=5. If it succeeds, "Passed" is displayed (in the Combined Noise region under the graph). If after 5 tries the crest factor is still not satisfactory, the display indicates "Failed".
The profile to be ETSI compliant, the cumulative distribution function must fit completely between the two limits of the mask.
Note: that if the crest factor fails then increasing the number of samples, more likely the calculation will be able to successfully resolve the crest factor requirement.
The Higher the sample number the longer the calculation time required.