Agilent Technologies 8560E User Manual page 305

The TDF (trace data format) command is used to select measurement
or parameter units. Traces are stored internally as integers in the
range from 0 to 600, where 0 represents the bottom graticule line and
600 represents the top graticule line. Because there are 10 graticule
divisions vertically, there will be 60 measurement units per graticule.
There is a small over-range area above the top graticule line (up to 610),
so traces can contain numbers slightly larger than 600.
To convert from measurement units to parameter units or from
parameter units to measurement units, you must have the following
information at the time that the trace data is measured: log-scale
setting (dB/division or linear), reference level, and the amplitude units
in which the reference level is expressed. For log scales where the
reference level is expressed in a dB-related unit, the following formulas
can be used:
Parameter Units = Reference Level
Measurement Units =
If reference level is not expressed in a dB-related unit, it must first be
converted to such a unit before using the formulas.
When using a linear display scale, the following formulas can be used
with the reference level expressed in volts. If the reference level is not
expressed in volts, it must be converted to volts before these formulas
are used.
Parameter Units = Reference Level
Measurement Units =
Notice that the interpretation of measurement units always depends on
the reference level and amplitude scaling of the display at the time that
the trace data was measured.
Position Units and Trace Elements
Traces are comprised of a fixed number of elements (601). Each
element has a fixed position on the horizontal axis of the trace. An
element is identified by specifying its horizontal position in position
units. Position units are integers, ranging from 1 to 601. The element
at the left end of a trace is always identified by a position value of 1.
The element at the right end of a trace has a position value of 601.
Chapter 5
+ Log Scale
Parameter Units Reference Level –
----------------------------------------------------------------------------------- -
Log Scale
Measurement Units
×
---------------------------------------------- -
Parameter Units
×
-------------------------------------- - 600
Reference Level
Programming
Data Transfer to Computer
Measurement Units 600
×
------------------------------------------------------------- -
60
×
60 + 600
600
–
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