Automatic Jitter Calibration System for Jitter Generator Accuracy in SDH/PDH Analyzer

摘要

This article introduces the calibration system of a jitter generator used in an SDH/PDH analyzer which is part of the digital wire communication measurement system built at Shanghai Institute of Measurement & Testing Technology (SIMT). As high as 10Gbit/s jitter output of the jitter generator with either electrical or optical port can be calibrated with the system. The instruments utilized include E4440 spectrum analyzer, 75Ω/50Ω impedance adapter and 83440C O/E converter dedicated for jitter calibration of the optical output signal. The Bessel Function ratio and Wide-band FM (WBFM) are adopted as calibration approaches, for small jitter value the Bessel Function ratio approach is used whereas the combination of Bessel Function ratio and WBFM approach is used when calibrating the 10UIp-p jitter accuracy required by JJG (YD) 044-1998 Regulation of Verification for SDH Transmission Analyzer. Automatic measurement software was also made with Labview from NI to improve measurement efficiency. The measurement results were compared with the same group of results from the same equipment measured by Metrology and Calibration Center of MII, the conclusion is that they are quite close to each other, which approves that the approach to realize the calibration system is rational and credible and the results are accurate and reliable.