About IF Offset Freq and Spur Avoidance

Some hardware can have a significant spur in the frequency domain at either the center frequency (LO feedthrough) or at an offset that is some fixed relationship to the center frequency (LO). This can significantly affect some measurements. Some hardware with an example of this are:

M9410A and M9411A PXI Vector Transceiver Modules, E7660A WB Transceiver, and other hardware that are zero IF architectures and tend to have significant LO feedthrough.
UXA with H1G that has some known spurs at fixed offsets from the center frequency.

In some Keysight hardware models, IF Offset Freq and/or IF Offset Freq Auto are available to use a different center frequency internally than the requested center frequency, then down convert to shift back to the requested center frequency. In effect, this method moves the spur relative to the user-requested center frequency if the spur is fixed in relationship to the hardware center frequency. When connected to hardware that supports spur avoidance, one or both of these parameters will appear in the VSA's list of input extensions for the connected hardware. Some hardware may allow manually entering an IF Offset Freq but not support IF Offset Freq Auto, which automatically attempts to avoid the highest spur. Other hardware may be able to avoid the highest spur (IF Offset Freq Auto), but not allow explicit control of the IF Offset Freq (in which case IF Offset Freq is greyed out).