NI 5650/5651/5652 Understanding Factory Calibration

National Instruments performs calibration of the NI 5650/5651/5652 that is relative to an NIST-traceable standard over the specified operating temperature range. Calibration consists of two major parts: frequency accuracy calibration and amplitude accuracy calibration.

For frequency accuracy, the 200 MHz system clock is calibrated against an NIST-traceable rubidium clock at room temperature and over the NI 5650/5651/5652 operating temperature range. It is important that the NI 5650/5651/5652 temperature stabilizes before critical frequency accuracy measurements are taken. Although the NI 5650/5651/5652 reference clock is sensitive to rapid changes in temperature, it has a slow response because its temperature varies with that of the metal RF enclosure, which has a high thermal inertia and therefore responds slowly to ambient temperature changes.

For amplitude accuracy, the ALC and attenuators are calibrated over the entire specified temperature range. The amplitude accuracy is calibrated against an NIST-traceable power meter for power levels greater than –40 dBm. For power levels below –40 dBm, a signal analyzer is used to make measurements relative to 0 dBm absolute. The accuracy of the power measurement for signals less than –40 dBm is thus dependent upon the relative accuracy of the signal analyzer. The relative accuracy of the signal analyzer is a function of its ADC linearity.

Note  Refer to the printed specifications document that shipped with your device for detailed RF signal generator specifications.

Caution  Factory calibration is invalidated if the RF enclosure is opened. To preserve guaranteed calibration, do not disassemble the NI 5650/5651/5652 RF enclosure.