Agilent Technologies FieldFox N9912A, Руководство пользователя

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Data Analysis Features 149

Then
Data->Mem
to store the current live trace into memory. A ‘beep’ sounds
to confirm the data trace has been saved to memory. There is no display
annotation that indicates that the memory trace has been stored.
o
Press
Data
to view only the data trace.
o
Press
Memory
to view only the memory trace.
o
Press
Data & Memory
to view both the live trace and the stored memory
trace.
How to perform Trace Math
Trace math is performed between a live trace and a memory trace. When one of
the following math operations are selected, the yellow data trace displays the
current measurement with the selected trace math applied. The math operation
symbol indicated below in [brackets] is displayed on the lower left corner of the
screen.

Press
Trace 6
.

If not already stored, press
Data->Mem
to store the current live trace into
memory.

Then
Data Math
.

Then choose one of the following:
o
Data + Memory
[ D+M ] Current measurement data is added to the data in
memory.
o
Data – Memory
[ D-M ] Current measurement data is subtracted from the
data in memory.
o
Data / Memory
[ D/M ] Current measurement data is divided by the data in
memory.
o
Math Off
[ Data ] Displays trace data with NO math applied.
About Math Operations
Data / Memory and Data - Memory math operations are performed on complex
linear data before it is formatted. Because data is often viewed in log format, it is
not always clear which of the two math operations should be used. Remember:
dividing linear data is the same as subtracting logarithmic data. The following
illustrates, in general, when to use each operation.
Use Data / Memory for normalization purposes, such as when comparing traces
"before" and "after" a change is made or when measuring trace noise. In the
following table, the Data/Mem values intuitively show the differences between
traces. It is not obvious what Data-Mem is displaying.
Values to compare Data/Mem Data-Mem
0.5 dB and 0.6 dB 0.1 dB -39 dB
0.5 dB and 0.7 dB 0.2 dB -33 dB
Use Data - Memory to show the relative differences between two signals. Use for
comparison of very small signals, such as the S11 match of two connectors.