PXIe-5668 Factory Calibration

Every PXIe-5668 vector signal analyzer is individually calibrated for accurate frequency and amplitude response at the factory. Each ships with a calibration certificate verifying NIST-traceable accuracy levels.

During frequency-response factory calibration, the PXIe-5668 measures an integrated high-precision calibration signal, which is compared against a NIST-traceable power sensor. Any error in the returned data is quantified as a set of calibration constants. NI-RFSA uses these calibration constants to calculate and to apply corrections to your analysis based on the spectrum of interest.

Note To preserve specified accuracy and NIST traceability, NI recommends returning all modules of the PXIe-5668 to the factory for recalibration every two years.
Note Opening the RF signal downconverter metal enclosure invalidates the PXIe-5668 calibration.

When calibrating the PXIe-5668 system, NI separately calibrates the PXIe-5606 RF signal downconverter, the PXIe-5624 IF digitizer, and the PXIe-5653 RF analog signal generator.

Both an RF response calibration and an IF response calibration are performed on the PXIe-5606. The downconverter RF response calibration corrects the RF downconverter response over frequencies and also provides temperature compensation. The RF response calibration is performed across frequency and across all reference levels. The specified RF response of the downconverter and the PXIe-5668 is met at all frequencies by interpolating between calibration frequencies. Therefore, accurate power measurements are obtained at all frequencies. The downconverter IF response calibration measures the response of the IF filters in the PXIe-5606 across the specified analog IF bandwidth. A factory IF response calibration is also performed on the PXIe-5624 IF digitizer.

NI-RFSA combines the PXIe-5606 and the PXIe-5624 frequency response corrections and generates an PXIe-5668 system frequency response correction in both magnitude and phase for all IF filter paths during self-calibration. The correction results in a flat magnitude response and minimal phase deviation across the bandwidth. For the through path the correction is applied for both spectrum and I/Q acquisitions. For the 300 kHz bandwidth, only the magnitude correction is applied, and only for spectrum acquisitions. I/Q acquisitions that use the 300 kHz IF filter path are not equalized, but both magnitude and phase equalization can be performed in software using the calibration information retrieved by using the niRFSA Get Frequency Response VI or the niRFSA_GetDeviceResponse function.