Agilent Technologies 8753ET User Manual page 377

Operating Concepts
Processing
Format
This operation converts the complex number pairs into a scalar representation for display, according to the
selected format. This includes group delay calculations. These formats are often easier to interpret than the
complex number representation. (Polar and Smith chart formats are not affected by the scalar formatting.) It
is impossible to recover the complex data after formatting, as shown in Figure 7-2.
Smoothing
This noise reduction technique smoothes noise on the trace. Smoothing is also used to set the aperture for
group delay measurements.
When smoothing is on, each point in a sweep is replaced by the moving average value of several adjacent
(formatted) points. The number of points included depends on the smoothing aperture, which can be
selected by the user. The effect is similar to video filtering. If data and memory are displayed, smoothing is
performed on the memory trace only if smoothing was on when data was stored into memory.
Format Arrays
The data processing results are now stored in the format arrays. Notice that the marker values and marker
functions are all derived from the format arrays in Figure 7-2. Limit testing is also performed on the
formatted data. The format arrays are accessible via GPIB.
Offset and Scale
These operations prepare the formatted data for display. This is where the reference line position, reference
line value, and scale calculations are performed, as appropriate to the format.
Display Memory
The display memory stores the display image for presentation on the analyzer. The information stored
includes graticules, annotation, and softkey labels. If user display graphics are written, these are also stored
in display memory. When a print or plot is made, the information is taken from display memory.
The display is updated frequently and synchronously with the data processing operations.
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