Stanford Research Systems SR785, Руководство по эксплуатации и программированию

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4-36 Display Setup Menu
SR785 Dynamic Signal Analyzer
Track
The Order Track measurement is a two dimensional plot of the amplitude of a given
order vs. RPM. The Track measurement can only be selected when Tracking is turned on
in the [Frequency] menu. The order and input channel displayed by the track
measurement is selected with the Track Setup submenu.
The amplitude recorded in the track is the Linear Spectrum, and contains both amplitude
and phase information.
Since the tracking feature uses the memory allocated to the Waterfall/Order buffer, the
waterfall buffer is not available for waterfall storage when tracking is enable.
RPM Profile
The RPM profile measurement is a two-dimensional plot showing RPM on the x-axis
and time on the y-axis.
Orbit
The order Orbit measurement is a two channel measurement whose real part is the real
part of Time Record Ch1 and whose imaginary part is the real part of Time Record Ch2.
Orbit is normally displayed with the Nyquist View (Time2 vertical vs Time1 horizontal).
Orbit measurements are often used in the order measurement group for shaft balancing.
Capture
The capture buffer stores sequential time domain data in memory. See ‘Capture’ in
Chapter 2 for more details. The capture measurement displays the contents of the capture
buffer. Order measurements can use this stored data as input data by choosing Playback
as the Input Source in the [Input] menu. In the order measurement group, the capture
buffer stores tachometer information as well as input data. Therefore, only a capture
buffer which was taken while the instrument was in the order group can be used as a
source of playback data for order measurements.
Note that in order group, the data in the capture buffer will not look like the data in the
order time record. The capture buffer contains data sampled at fixed time intervals. The
time record contains data which is processed to yield samples at equal positions around
the shaft.
To graphically expand a region of the display, use the Pan and Zoom functions in the
[Display Setup] menu. The capture buffer display will automatically pan as the capture
fill and playback progress through the buffer. During capture fill, if the capture buffer
contains more points than can be displayed, points are skipped. This speeds up the
display update so that it keeps up with the real time capture but allows visual aliasing to
occur. Once capture is complete, the display is redrawn showing the envelope of all
points, eliminating any visual aliasing effects.
User Functions
A User Function displays the results of a user defined math function. User Functions
defined within the Order Measurement Group may include order measurement results.
Use the [User Math] menu to define a function.