Agilent Technologies 3588A Betriebsanweisung PDF herunterladen (Seite 213)

Reconstructing a Trace

The simplest SDF file defines a single trace. A trace consists of a series of discrete points, each defined

by an X-axis value and a Y-axis value. This section tells you how to locate or calculate a single trace’s

X-axis and Y-axis values.

X-axis Values

A trace’s X-axis values are stored in one of two SDF records: the Data Header record, or the X-axis Data

record. The location used depends on whether or not consecutive points are evenly spaced along the

X-axis:

Evenly-spaced points: X-axis values are stored in the Data Header record.

Unevenly-spaced points: X-axis values are stored in the X-axis Data record.

Field 11 of the Data Header record (xResolution_type) is an indicator of X-axis spacing. Consecutive

points are evenly spaced if xResolution_type has value of 0 or 1; they are unevenly spaced if it has a

valueof2,3,or4.

When consecutive trace points are evenly spaced along the X-axis (xResolution_type = 0, or 1), the SDF

file does not include an X-axis Data record. Instead, the X-axis values of these points are completely

defined by three fields in the Data Header record:

abscissa_firstX: tells you the X-axis value of the first point.

abscissa_deltaX: tells you the X-axis spacing between points.

num_of_points: tells you how many discrete points the trace is composed of.

You can calculate X-axis values this way when xResolution_type is 0 (linear resolution):

x0 = abscissa_firstX

x1 = x0 + abscissa_deltaX

x2 = x0 + abscissa_deltaX * 2

x3 = x0 + abscissa_deltaX * 3

xn = x0 + abscissa_deltaX * n (where n = num_of_points −1)

Standard Data Format (SDF)

B-27

1 2 ... 208 209 210 211 212 213 214 215 216 217 218 ... 253 254

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Agilent Technologies 3588A Betriebsanweisung Seite 213