Abstract：Illustrated by the case of Medium Frequency Attenuation noise measurement, a mismatch model is proposed to solve the problem of larger uncertainty of noise transfer of domestic laboratories. Based on the research of measurement uncertainty for complex quantities with unknown phase, an optimal estimation of mismatch uncertainty is described. With the more accuracy estimation of mismatch uncertainty, the effectiveness and the use strategy of the isolation attenuator are discussed. The best solution of mismatch in noise measurement is proposed at last.
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2016, Vol. 37 
