Reducing the measurement error of signal propagation delays using an optical reflectometer with picosecond resolution

Abstract

The problems requiring high-precision measurements of signal propagation delays in optical fibers are considered. Design features of a pulsed optical reflectometer with a picosecond resolution designed for measuring propagation delays of a signal are considered. It is shown that the error of such a reflectometer includes the additive and multiplicative components. A method for determining the additive component of the optical reflectometer error based on measurements of signal delays introduced by individual optical fiber coils and the total delay introduced by series-connected coils is proposed. The requirements to the measurement conditions are formulated and the results of the error estimation of the proposed method are presented. To exclude the multiplicative component of the reflectometer error, a method for determining corrections to the reflectometer readings is proposed. The method is based on measuring the propagation delays of the signal in the coils of the optical fiber, first using reference equipment (installation for measuring the propagation delay of the signal), and then using an optical reflectometer, and then calculating the differences of the obtained measurement results. The scheme of installation for measurements of a propagation delay of signal in a coil of optical fiber is presented, the principle of operation of measuring installation is described. The results of the estimation of the error in determining the corrections to the reflectometer readings by the proposed method are presented. It is shown that the exclusion of the additive and multiplicative components of the error will reduce the error of optical reflectometers to values less than ± 100 ps.