Examines the input signal to calculate the peak power level and sets it as the value of the Reference Level property. Use this VI to calculate an approximate setting for the reference level.

The RFmxNR Auto Level VI completes the following tasks:

  1. Resets the mixer level, mixer level offset, and IF output power offset.
  2. Sets the starting reference level to the maximum reference level supported by the device based on the current RF attenuation, mechanical attenuation, and preamplifier enabled settings.
  3. Iterates to adjust the reference level based on the input signal peak power.
  4. Uses immediate triggering and restores the trigger settings back to user setting after the execution.

When using NI-PXIe 5663, NI-PXIe 5665, or NI-PXIe 5668R device, NI recommends that you set an appropriate value for mechanical attenuation before calling the RFmxNR Auto Level VI. Setting an appropriate value for mechanical attenuation reduces the number of times the attenuator settings are changed by this function; thus reducing wear and tear, and maximizing the life time of the attenuator.


icon

Inputs/Outputs

  • cstr.png Selector String —

    Selector String specifies a selector string comprising of the signal name. If you do not specify the signal name, the default signal instance is used. The default is "" (empty string).

    Example:

    "signal::sig1"

    You can use the RFmxNR Build Signal String VI to build the selector string.

  • cgenclassrntag.png Instrument Handle In —

    Instrument Handle In specifies the RFmx session refnum. Instrument Handle In is obtained from the RFmxInstr Initialize NIRFSA VI.

  • cdbl.png Measurement Interval (s) —

    Measurement Interval specifies the acquisition length. This value is expressed in seconds. Use this value to compute the number of samples to acquire from the signal analyzer. The default value is 10 ms.

    Auto Level VI does not use any trigger for acquisition. It ignores the user-configured trigger properties. NI recommends that you set a sufficiently high measurement interval to ensure that the acquired waveform is at least as long as one period of the signal.

  • cerrcodeclst.png error in (no error) —

    error in describes error conditions that occur before this node runs. This input provides standard error in functionality.

  • igenclassrntag.png Instrument Handle Out —

    Instrument Handle Out passes a reference to your RFmx session to the next VI.

  • idbl.png Reference Level —

    Reference Level returns the estimated peak power level of the input signal. This value is expressed in dBm. The default value of this parameter is hardware dependent.

  • ierrcodeclst.png error out —

    error out contains error information. This output provides standard error out functionality.