RFmxDemod Auto Level (VI)

RFmx Demod 19.1 Help

Edition Date: October 2019

Part Number: 374641M-01

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Owning Palette: Configuration

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 help calculate an approximate setting for the reference level.

The RFmxDemod Auto Level VI does the following tasks:

  1. Resets the mixer level, mixer level offset, and IF output power level 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 preamp 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.

You can also specify the starting reference level using the Auto Level Initial Ref Level property.

When using NI 5663, 5665, or 5668R devices, NI recommends that you set an appropriate value for mechanical attenuation before calling the RFmxDemod 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.

RFmxDemod Auto Level

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

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Bandwidth specifies the bandwidth, in Hz, of the signal to be analyzed.

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Measurement Interval specifies the acquisition length. This value is used to compute the number of samples to acquire from the signal analyzer. This value is expressed in seconds. 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.

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Selector String comprises of the signal name. If you do not specify the signal name, the default signal instance is used. The default value is "" (empty string).

Example:

""

"signal::sig1"

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

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

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

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Reference Level returns the estimated peak power level of the input signal. This value is expressed in dBm for RF devices and Vpk-pk for baseband devices.

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

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