Use subspan overlap process to eliminate or reduce analyzer spurs. To enable this feature, specify a non-zero percentage overlap between consecutive subspans in a spectrum acquisition.

Syntax

RFMXINSTR_ATTR_SUBSPAN_OVERLAP

Numeric Value

Data Type

Access

Applies To

50

float64

Read/Write

N/A

Remarks


If a value greater than 0 is specified, then for each spectral line in the resulting spectrum, the driver acquires data twice with slightly different hardware settings, so that the analyzer spurs, if any, are present at different frequencies in the two acquisitions. Typically, LO frequency is shifted between the acquisitions causing analyzer spurs that are relative to the LO frequency, to move from one frequency to another. Those spurs, which are present in only one of the acquisitions for each spectral line, get removed.

The subspan overlap feature will not remove any spurs from the Device Under Test or modify the signal being measured; unlike the analyzer spurs, the spurs in the signal being measured stay at a constant frequency in the two acquisitions.
Note

Subspan overlap process effectively is performing minimum averaging, which might reduce the measured noise floor level. RFmx Spectrum Averaging can be enabled to minimize the effect of subspan overlap on the noise floor.

Note

RFmx may apply further shifts to the specified value to accommodate fixed-frequency edges of components such as preselectors.

You do not need to use a selector string if you want to configure this attribute for all signal instances. Specify the signal name in the selector string if you want to configure or read that signal instance. Refer to the Selector String topic for information about the string syntax.

The default value is 0.

Valid values

Name (value)

Description

PXIe-5820/5830/5831/5832/5840/5841/5860

0

PXIe-5842

0, 50

PXIe-5665/5668

0 to <100

Supported devices: PXIe-5665/5668, PXIe-5820/5830/5831/5832/5840/5841/5842/5860