National Instruments Network Adapter NI PXIe-6672 User Manual

Also see for Network Adapter NI PXIe-6672: User manual Installation guide CALIBRATION PROCEDURE

National Instruments Network Adapter NI PXIe-6672 User Manual Manual pdf 34 page image

© National Instruments Corporation 4-1 NI PXIe-6672 User Manual4CalibrationThis chapter discusses the calibration of the NI PXIe-6672.Calibration consists of verifying the measurement accuracy of a deviceand correcting for any measurement error. The NI PXIe-6672 is factorycalibrated before shipment at approximately 25 °C to the levels indicatedin Appendix A, Specifications. The associated calibration constants—thecorrections that were needed to meet specifications—are stored in theonboard nonvolatile memory (EEPROM). The driver software uses thesestored values.Factory CalibrationThe factory calibration of the NI PXIe-6672 involves calculating andstoring four calibration constants. These values control the accuracy offour features of the device, which are discussed in the following sections.TCXO FrequencyThe TCXO frequency can be varied over a small range. The outputfrequency of the TCXO is adjusted using this constant to meet thespecification listed in Appendix A, Specifications. This calibrationapplies only to the NI PXIe-6672.PXI_CLK10 PhaseWhen using the PLL to lock PXI_CLK10 to an external reference clock, thephase between the clocks can be adjusted. The time between rising edgesof PXI_CLK10 and the input clock is minimized using this constant.DDS Start Trigger PhaseTo start the DDS reliably, the DDS start trigger must arrive within a certainwindow of time. The phase of the DDS start trigger is controlled by thisconstant to meet the setup and hold-time requirements of the DDS.