摘要: In this document, we provide the total (or combined) uncertainty of phase modulation (PM) and amplitude modulation (AM) noise measurement of the NIST portable noise standard calculated from the individual measurement uncertainties... 展开 In this document, we provide the total (or combined) uncertainty of phase modulation (PM) and amplitude modulation (AM) noise measurement of the NIST portable noise standard calculated from the individual measurement uncertainties. NIST provides an on-site calibration service (77135C) of the accuracy of PM and AM noise and noise floor of the measurement systems at the customer's site by use of two separate portable PM/AM secondary noise standards. One noise standard is for carrier frequencies of 5 MHz, 10 MHz, and 100 MHz, designated as model 510100, and the other for carrier frequencies of 10.6 GHz, 21.2 GHz, and 42.4 GHz, designated as model 102040. The PM and AM noise of the noise standard are usually measured twice at NIST, once before sending it to the customer (the out measurement) and a second time after receiving it back (the in measurement). The customer uses its PM/AM noise measurement system and measures the calibrated noise level of the NIST secondary noise standard. Customer results are compared with the average of the in and out measurements at NIST. If the results are within the measurement uncertainty then the calibration is certified and a PASS calibration report is issued. When there is significant discrepancy in the results, the customer is advised to recheck the measurement configuration and re-measure. If the customer results cannot be achieved within the measurement uncertainty, a FAIL calibration report is then issued. 收起