Specifies the method for performing the Spectrum measurement.

Syntax

Namespace: NationalInstruments.RFmx.SpecAnMX

public enum RFmxSpecAnMXSpectrumMeasurementMethod

Members

NameValueDescription
Normal0

The Spectrum measurement acquires the spectrum using the same signal analyzer setting across frequency bands.

SequentialFft2

The Spectrum measurement acquires I/Q samples for a duration specified by the SpectrumSweepTimeInterval method. These samples are divided into smaller chunks. If the method SpectrumRbwFilterAutoBandwidth is True, The size of each chunk is defined by the SpectrumSequentialFftSize method. If the method Spectrum RBW Auto is False, the Spectrum Sequential FFT Size is auto computed based on the configured SpectrumRbwFilterBandwidth. The overlap between the chunks is defined by the SpectrumFftOverlapMode method. FFT is computed on each of these chunks. The resultant FFTs are averaged as per the configured averaging type in the method SpectrumFftOverlapTypeto get the spectrum. Sequential FFT method should be used for the following scenarios.

  1. While performing fast Spectrum measurements by utilizing smaller FFT sizes. However, accuracy of the results may be reduced.  

  2. When measuring signals with time-varying spectral characteristics, sequential FFT with overlap mode set to Automatic should be used.  

  3. For accurate power measurements when the power characteristics of the signal vary over time, averaging is allowed.  


The following methods have limited support when you set the RFmxSpecAnMXSpectrumConfiguration.ConfigureMeasurementMethod method to SequentialFft.

  • The RFmxSpecAnMXSpectrumConfiguration.SetVbwFilterAutoBandwidth method will only support True value.  

  • The RFmxSpecAnMXSpectrumConfiguration.SetRbwFilterType method will only support FftBased value.  

  • The RFmxSpecAnMXSpectrumConfiguration.SetSweepTimeAuto method will only support False value.  

  • The RFmxSpecAnMXSpectrumConfiguration.SetAveragingCount method will only support a value greater than or equal to 1.  

  • The RFmxSpecAnMXSpectrumConfiguration.SetNumberOfAnalysisThreads method will only support a value of 1.  

  • The RFmxSpecAnMXSpectrumConfiguration.SetAmplitudeCorrectionType Method will only support a value of RFCenterFrequency.  

  • The RFmxSpecAnMXSpectrumConfiguration.SetVbwFilterVbwToRbwRatio Method will only support a value greater than or equal to 3.  

Note

For multi-span FFT, the averaging count should be 1.