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The major trends in the development of network communications are examined. Based on the latest specifications for frequency and time synchronization systems, it is concluded that it is necessary to modernize the new generation of equipment for frequency-time support of the communications systems. Current issues in the metrological support of 5G communications systems are discussed. A structure of a future universal system for measurement of the parameters of the synchronization systems of 5G communications systems is proposed. Its technical characteristics and operational capabilities are discussed.

We study the possibility of application of SATRE modems for the transmission of reference time signals with optical carrier over fiber lines with lengths of up to 200 km. We experimentally estimated the uncertainties of comparison of time scales for the fiber communication lines with the help of SATRE modems.

We present a system of transmission of reference frequency and time signals to non-interrogating and interrogating measuring facilities of the ground-based GLONASS complex for control of onboard time scales of the navigation system spacecraft. The proposed transmission system is implemented using fiberopticcommunication lines. We present results of experimental studies of the error in the transmission of reference frequency and time signals using fiber-optic communication lines.

An experimental plant for transmission of a reference signal along a fiber-optic communication line with electronic compensation of disturbances introduced by the line is described. Results of measurements of the error associated with transmission of the 100-MHz reference signal of the hydrogen oscillator of the State Primary Standard of the Units of Time and Frequency and the National Time Scale GET 1–2012 along a 100–200 km fiber-optic communication lines are presented.

We present a method for disseminating reference radio frequencies over a fiber-optic line. We describe a circuit for electronic compensation of phase perturbations in a transmitted 100 MHz reference signal over an optical fiber. We give experimental measurement results for the Allan deviation of a 100 MHz reference signal transmitted to the remote end of a 100-km fiber link.

A scheme of standard RF signal transmission over an electronically stabilized fiber link is described in the paper. The system was tested for fiber link length up to 85 km. In this scheme an intermediate controlled crystal oscillator of 100 MHz was used as a compensation node. Experimental results of the 100 MHz RF signal transmission over the 85 km optical fiber are presented. It is demonstrated that using a system of electronic compensation provides significant advantages in spatially separated standards comparison.