Reducing Recall Time; Understanding Spur Avoidance - Agilent Technologies 8753ET User Manual

Optimizing Measurement Results

Reducing Recall Time

Reducing Recall Time
To reduce time during recall and frequency changes, the raw offset function and the spur
avoidance function can be turned off. To turn these functions off, press
System
.
CONFIGURE MENU RAW OFFSET OFF SPUR AVOID OFF
The raw offset function is normally on and controls the sampler and attenuator offsets.
The spur avoidance function is normally on and generates values as part of the sampler
offset table. Depending on the state, the creation of this table takes approximately
15 percent of the time during the recall of an instrument state.
To save time at recalls and during frequency changes, both functions should be turned off.
This will avoid generating the sampler offset table.
Raw offsets may be turned on or off individually for each channel. They follow the channel
coupling. For dual channel operation, raw offsets should be turned off for each channel if
the channels are uncoupled. Spur avoidance is always coupled between channels, therefore
both channels are turned on or off at the same time.
NOTE Both functions must be turned off to realize the recall time savings.
Refer to "Specifications and Characteristics" chapter in the reference guide for examples of
recall state times with the following functions on or off: raw offsets, spur avoidance, and
blank display. Using blank display may speed up recall times.

Understanding Spur Avoidance

In the 400 MHz to 3 GHz range, where the source signal is created by heterodyning two
higher frequency oscillators, unwanted spurious mixing products from the source may be
present at the output. These spurs can become apparent in filter measurements when
filters have greater than 80 dB rejection.
Spur avoidance slightly moves the frequency of both oscillators such that the source
frequency remains the same but the spurious mixing products shift out of the
measurement receiver range. The calculation of the exact frequency points where the
shifting must occur (stored in the sampler offset table) increases the time needed to change
or recall instrument states. Selecting and
SPUR AVOID OFF RAW OFFSET OFF
eliminates this calculation.
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