This chapter discusses the calibration of the PXIe-6672.

Calibration consists of verifying the measurement accuracy of a device and correcting for any measurement error. The PXIe-6672 is factory calibrated before shipment at 23 ±5 °C to the levels indicated in the device's specifications. The associated calibration constants—the corrections that were needed to meet specifications—are stored in the onboard nonvolatile memory (EEPROM). The driver software uses these stored values.

Factory Calibration

The factory calibration of the PXIe-6672 involves calculating and storing four calibration constants. These values control the accuracy of four features of the device, which are discussed in the following sections.

TCXO Frequency

The TCXO frequency can be varied over a small range. The output frequency of the TCXO is adjusted using this constant to meet the specification listed in the device's specifications. This calibration applies only to the PXIe-6672.

PXI_CLK10 Phase

When using the PLL to lock PXI_CLK10 to an external reference clock, the phase between the clocks can be adjusted. The time between rising edges of PXI_CLK10 and the input clock is minimized using this constant.

DDS Start Trigger Phase

To start the DDS reliably, the DDS start trigger must arrive within a certain window of time. The phase of the DDS start trigger is controlled by this constant to meet the setup and hold-time requirements of the DDS.

DDS Initial Phase

The phase of the DDS output is adjusted using this constant so that the DDS outputs from multiple PXIe-6672 modules are aligned.

Additional Information

Refer to ni.com/calibration for additional information on NI calibration services.