PhaseStation 53100A User’s Manual V1.04 25-Apr-2022 97
Show separated xDEV variances (N-cornered hat) when available (Ctrl-h)
This display option provides an alternative way to view Allan deviation and other
statistical traces. Under appropriate conditions, it can reveal aspects of oscillator
performance that would otherwise be inaccessible in a conventional measurement with
a single reference source.
When the N-cornered hat view is enabled in the N=3 case as shown above, TimeLab will attempt
to isolate and display the individual contribution of each of three devices to a set of three
stability measurements. Although an in-depth discussion of this technique is outside the scope
of this document, Application Note 53100A-2 (Dual-Reference Noise and Stability Measurements
with the PhaseStation 53100A) presents a detailed “case study” in which the three-cornered hat
methodology is used to provide mutual assessments of high-performance crystal oscillators.
Please refer to this application note for more information.
Currently, N values other than 3 are considered investigational, and are not supported.
When viewing three-cornered hat traces, it is strongly recommended that only the three
participating measurements are enabled for display. All other plots should either be cleared
with File→Close selected plot (Del) or marked invisible with Display→Toggle visibility of
selected plot (v).
To configure the PhaseStation 53100A for three-cornered hat measurements, see the
description of the Measure three independent DUTs (three-cornered hat) measurement role
on page 134.
Cross Allan deviation measurements are often preferable to the three-cornered hat
methodology, particularly when the goal of the measurement is to gather data for only one
DUT. See the description of the Measure single DUT with cross ADEV statistics measurement
role on page 136 for more information.
Figure 45: Three-cornered hat display
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