Specifies the step size for tuning the LO phase-locked loop (PLL).

You can only tune the LO frequency in multiples of the LO Frequency Step Size property. Therefore, the LO frequency can be offset from the requested center frequency by as much as half of the LO Frequency Step Size property. This offset is corrected by digitally frequency shifting the LO frequency to the value requested in Downconverter Center Frequency property.

Note For PXIe-5831 with PXIe-5653, PXIe-5832 with PXIe-5653, this property is ignored if PXIe-5653 is used as the LO source.

The valid values for this property depend on the LO PLL Fractional Mode property.

PXIe-5644/5645/5646: If you set the LO PLL Fractional Mode property to Disabled, the specified value is coerced to the nearest valid value.

PXIe-5840: If you set the LO PLL Fractional Mode property to Disabled, the specified value is coerced to the nearest valid value that is less than or equal to the desired step size.

LO PLL Fractional Mode Enabled Property Setting LO Frequency Step Size Property Valid Values on PXIe-5644/5645 LO Frequency Step Size Property Valid Values on PXIe-5646 LO Frequency Step Size Property Valid Values on PXIe-5840/5841 LO Frequency Step Size Property Valid Values on PXIe-5830/5831/5832 LO Frequency Step Size Property Valid Values on PXIe-5841 with PXIe-5655, PXIe-5842*
Enabled 50 kHz to 24 MHz 50 kHz to 25 MHz 50 kHz to 100 MHz LO1: 8 Hz to 400 MHz

LO2: 4 kHz to 400 MHz		 1 nHz to 50 MHz
Disabled 4 MHz, 5 MHz, 6 MHz, 12 MHz, 24 MHz 2 MHz, 5 MHz, 10 MHz, 25 MHz 1 MHz, 5 MHz, 10 MHz, 25 MHz, 50 MHz, 100 MHz LO1: --

LO2: --		 1 nHz to 50 MHz
Note This property is not supported on a MIMO session.

You do not need to use a selector string if you want to configure this property for all signal instances. Specify the signal name in the selector string if you want to configure or read that signal instance. Refer to the Selector Strings topic for information about the string syntax.

Default values
PXIe-5644/5645/5646 200 kHz
PXIe-5830 2 MHz
PXIe-5831/5832 (RF port) 8 MHz
PXIe-5831/5832 (IF port) 2 MHz, 4 MHz
PXIe-5840/5841 500 kHz
PXIe-5842 1 Hz
Note The default value for PXIe-5831/5832 depends on the frequency range of the selected port for your instrument configuration. Use RFmxInstr Get Available Ports VI to get the valid port names.

Supported devices: PXIe-5644/5645/5646, PXIe-5830/5831/5832/5840/5841/5842

Remarks

The following table lists the characteristics of this property.

Short Name LO Freq Step Size (Hz)
Data type cdbl.png
Permissions Read/Write
High-level VIs N/A
Resettable Yes