Estimation of the uncertainty for a phase noise optoelectronic metrology system

A configuration of phase noise measurement system operating in X-band (8.2-12.4 GHz) using a photonic delay line as a frequency discriminator is presented in this paper. This system doesn’t need any excellent frequency reference and works for any frequency in this band. Oscillator frequency fluctuation is converted to phase frequency fluctuation through the delay line. The measured phase noise includes the Device Under Test (DUT) noise and the instrument background. Then the use of a cross correlation decreases the cross spectrum terms of uncommon phase noise as √(1/m), where m is the average number. Using cross correlation on 500 averages, noise floor of the instrument £(f) becomes respectively -150 and -170 dBc/Hz at 101 and 104 Hz from the 10 GHz carrier (-90 and -170 dBc/Hz including 2 km delay lines). We then focus on determining uncertainty. There are two categories of uncertainties terms : ”type A”, statistic contribution such as repeatability and experimental standard deviation; ”type B” due to various components and temperature control. Elementary term of uncertainty for repeatability is found to be equal to 0.68 dB. Other elementary terms still have lower contributions. Its leads to a global uncertainty of 1.58 dB at 2σ.