Metric Halo SpectraFoo - Manual (Page 47)

Instruments
47
Auto-Sensitivity Mode
Often the dynamic range of the signals being monitored is quite large. When the dynamic range is large, no one
setting of the sensitivity is correct to show all of the details of the phase of the signal. Sometimes the sensitivity
is too small and the lissajous trace looks like a single dot. Other times the sensitivity is too large and the
trace extends way past the edge of the meter. Auto Sensitivity mode automatically calculates the appropriate
sensitivity setting for the meter at each instant of time. It is activated by checking the Auto Sensitivity button
in the Lissajous Control window.
Hi-Res Mode
To increase the speed of display, the Lissajous scope computes its display from every fourth sample. This gives
a reasonably accurate representation of the phase information. It also generates a display that is not quite
as smooth and clean as an analog scope. The Lissajous Hi-Res Mode makes the Lissajous scope compute
its display from every sample. This mode is activated by checking the Hi-Res Mode button in the Lissajous
Control window.
Phase Torch™
This is a revolutionary tool which compares the phase difference between two channels as a function of
frequency, independent of power. The display looks like a multicolored fountain or torch. The graphing scheme
is a polar pattern. The radius from the center is determined by the frequency and the angle is determined by
the phase difference between the left and right channels. The center of the graph represents DC while the outer
radius represents the Nyquist value.
In order to help you intuitively identify the frequencies, the phase points are also colored according to their
frequency. You can get a color – frequency calibration chart by clicking on the Phase Torch’s parameter control
button, and viewing the relationship between the Power Threshold’s power scale and the frequency range in
the color bar.
A mono (in-phase) signal is indicated by what looks like a torch precisely aligned with the Y axis of the scope.
The in-phase torch illustrated below “fuzzes-out” at high-frequencies because the signal used to create the
display did not have very much high frequency energy so the display is dominated by noise at high frequencies.
An out–of–polarity signal appears as a negative version of a mono signal. Delays appear as spirals within the
scope.
Figure 3.53: Phase Torch™
This meter is very useful when recording a musical instrument with multiple microphones. You can use the
Phase Torch to identify the frequency ranges in which phase cancellations are occurring as a result of the comb