RFmx Error -1074118437 When Using the Downconverter Frequency Offset Property in Spectrum Mode

Updated Aug 28, 2024

Reported In

Software

  • RFmx

Driver

  • NI-RFSA

Issue Details

When in spectrum mode, I get error -1074118437 when trying to set the Downconverter Frequency Offset property stating that the attribute is not supported in spectrum mode, but I am able to set the Downconverter Center Frequency property.
RFmx DCFO error.PNG

Why do I get this error and how can I use the Downconverter Frequency Offset property?

Solution

When in spectrum-only mode, only certain instruments can use the Downconverter Center Frequency property. The Downconverter Frequency Offset property is only available to use when the analyzer is in IQ mode, such as taking an IQ or TXP measurement. It is recommended that you use the Downconverter Center Frequency property when in spectrum mode or add an IQ measurement during the acquisition to force the driver into IQ mode to be able to use the Downconverter Frequency Offset property. 

Additional Information

RFmx Spectrum measurements and RFSA Spectrum acquisition mode are not intended to provide fine control over the hardware. Their intent is to provide a cleaner spectrum and it does this by using LO offsets to avoid the LO showing up in the spectrum. The driver will automatically calculate and control the LO offset which results in the user not being able to directly control this when in spectrum mode. 

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