Toggle Offset Soft Key; Offset (As Error) Soft Key - Fluke 9640A Series Instruction Manual

9640A
Instruction Manual

Toggle Offset Soft Key

Note that while the Offset field is present, a Toggle Offset soft key is also present. In the
following Leveled-Sine – Toggle Offset screen, the Toggle Offset soft key may be
pressed at any time to remove the offset from the output. The initial (Offset = 0) value is
restored and the Offset indicator on the Status Bar turns off.
An additional press of the Toggle Offset soft key reapplies the offset, allowing
convenient toggling of the output between its initial and its offset values.

Offset (As Error) Soft Key

In a typical calibration application in which the Instrument has been set to a target Level
(or Frequency), an offset may be applied until the UUT reads exactly the target value.
The offset setting is now related to the UUT error.
When the Offset field is the focus field, both its display and edit format may be switched
from an expression of offset of Instrument output to an expression of Error in the UUT.
This results in a convenient and accurate readout of UUT error for which display units
may be selected independently.
If a UUT reads high (and has an Error of +Err,) it is clear that the
Instrument will have to be adjusted down by an Offset –Off to achieve the
target reading.
It is often thought that Offset and Error will merely be of opposing signs,
i.e. +Err = -Off. This is only true if Offset and Error are both expressed in
ratio units of dB. To express Error and Offset in % (or ppm), however,
while the same is approximately true for small errors, a more substantial
Error of, say, +10% will require an Instrument Offset of only -9.091% to
achieve the target reading. The two are non-linearly related. This
calculation and display feature is frequently of great benefit.
3-18
Leveled Sine - Toggle Offset
Note
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