Why Do I Get a "Meas UNCAL" Message During Zero Span Measurement in Signal Analyzer Mode?

The “Meas UNCAL” message during zero span measurements indicates that the capacity of the capture memory has been exceeded for the current combination of RBW and sweep time.

The FieldFox hardware has limited capture memory in its gate array. When this error occurs, it is necessary to decrease the RBW and/or decrease the sweep time.

Note: the “Meas UNCAL” message is general purpose and may occur for other reasons as well. It is used when the measurement results are questionable.