Models LB480A/LB680A
USB Powe™
Product Manual PPA (Pulse Profiling Application)
Revision: 08/02/11
23
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
Time Between Samples
Length of Trace
10 usec
0.0208 usec
480 points
20 usec
0.0208 usec
960 points
50 usec
0.0208 usec
2400 points
100 usec
0.0208 usec
4800 points
200 usec
0.0208 usec
9600 points
500 usec
0.05 usec
10000 points
1000 usec
0.1 usec
10000 points
2000 usec
0.2 usec
10000 points
5000 usec
0.5 usec
10000 points
10000 usec
1.0 usec
10000 points
20000 usec
2.0 usec
10000 points
50000 usec
5.0 usec
10000 points
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.
