Arb:IQ Rate (S/s) Property

NI RF Signal Generators Help (NI-RFSG 18.1)

Edition Date: June 2018
Part Number: 371025V-01
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Short Name: IQ Rate (S/s)

Property of niRFSG

This property specifies the I/Q rate of the arbitrary waveform. The I/Q rate is coerced to a value the hardware can achieve. Read this value back after setting it to see the actual I/Q rate. NI-RFSG internally uses an FIR filter with flat response up to (0.4 × IQ rate). Given a desired signal with the maximum frequency content f, sample the signal at an I/Q rate greater than or equal to (f/0.4).

This property only applies when the Generation Mode property is set to Arb Waveform or Script.

To set this property, the NI-RFSG device must be in the Configuration state.

Supported Devices: PXIe-5644/5645/5646, PXI-5670/5671, PXIe-5672/5673/5673E, PXIe-5820/5840

The following table lists available I/Q rates.

Device Available Rates
PXIe-5644/5645 Up to 120 MS/s.
PXIe-5646 Up to 250 MS/s.
PXI-5670 50 MS/s, 100 MS/s
PXI-5671 50 MS/s, 100 MS/s, and (100 MS/s)/n, where n is divisible by 2 between 12 to 512, and divisible by 4 between 512 to 1,024 (n = 12,14,16, ...,512, 516, 520, ...,1024). Setting the I/Q rate to one of these values enables the DUC.
PXIe-5672 Up to 100 MS/s.
PXIe-5673/5673E Up to 200 MS/s.
Note  If an PXIe-5450 with module revisions A or B is used as part of your PXIe-5673/5673E, the NI-FGEN Compensate for Filter Group Delay property is disabled if the requested I/Q rate is less than 1.5 MS/s.
PXIe-5820/5840 Up to 1.25 GS/s.

Setting this property to 50 MS/s on the PXI-5670/5671, PXIe-5672 has the following implications:

  • The NI-RFSG driver is forced to place the carrier frequency at 18 MHz ± 1 MHz to avoid aliasing. Forcing the carrier frequency to that point implies that NI-RFSG does not have the freedom to pick a carrier frequency that could optimize the waveform size if phase continuity is enabled.
  • Output signal bandwidth must be less than 5 MHz to avoid aliasing.
  • Close-in phase noise is higher.
Note  Use this property to associate an I/Q rate with a waveform.

Related Topics


Assigning Properties or Attributes to a Waveform—Refer to this topic for more information about using this property to associate an I/Q rate with a waveform.

Digital Upconverter


The following table lists the characteristics of this property.

Datatype fD
High-level VIs niRFSG Write Arb Waveform
Channel-based No


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