Ladybug PowerSensor+ LB480A Product Manual page 23

Models LB480A/LB680A USB PowerSensor+™
Product Manual PPA (Pulse Profiling Application)
Setting the Frequency is essential to making accurate measurements. As with all power sensors, LadyBug corrects
the readings based on a known incoming frequency. In the past this has been referred to as calibration factors or
simply cal factors. Large errors can occur without setting the Frequency especially at the upper end of operation.
Therefore, the Frequency setting must correspond to the input to achieve the most accurate measurements.
The following table shows the relationship between Sweep Time, sample rate, and total number of samples. Notice
that the resolution of most computer displays is limited to somewhere between 1000 and 2000 points. This is a
physical limitation of all displays. However, the measured data has substantially more resolution. Accordingly, you
must zoom in to see maximum detail on a 10000 point trace. By providing a panoramic view, and a second potentially
more detailed measurement view, LadyBug enables you to see both the forest and the trees.
The resolution of the trace changes with the Sweep Time as shown in the table below. Normally this resolution would
be a serious and perhaps unacceptable limitation. However, LadyBug provides a delayed measurement capability.
This enables you to see small portions of data in greater detail long after a trigger has been acquired.
Sweep Time
10 usec
20 usec
50 usec
100 usec
200 usec
500 usec
1000 usec
2000 usec
5000 usec
10000 usec
20000 usec
50000 usec
The Reference Level shifts the viewing area and it does not affect the measured values. When you click the reference
level button the dialog box allows you to select a Resolution coupled with a viewable dynamic range (due to a fixed
number of vertical divisions). The Panoramic Trace and Measurement Trace panes always display 10 vertical and 10
horizontal divisions. The Reference Level can be set using one of the preset values or a user defined value.
The Reference Level selections apply to both the Measurement view and the Panorama view. The Resolution setting
apply only to the Measurement view. There is provision for offsetting the input over the range shown. Select Offset to
enter a value and to enable/disable this functionality. The Offset and Response annunciators are visible above and to
the right of the measurement grid.
Revision: 08/02/11
Time Between Samples
0.0208 usec
0.0208 usec
0.0208 usec
0.0208 usec
0.0208 usec
0.05 usec
0.1 usec
0.2 usec
0.5 usec
1.0 usec
2.0 usec
5.0 usec
Length of Trace
480 points
960 points
2400 points
4800 points
9600 points
10000 points
10000 points
10000 points
10000 points
10000 points
10000 points
10000 points
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