TIME AND FREQUENCY MEASUREMENTS AN ANALYSIS OF THE FREQUENCY INSTABILITY OF THE GROUP SIGNAL OF AN ENSEMBLE OF ACTIVE HYDROGEN STANDARDS

Modern time and frequency keeping systems are usually composed of several atomic clocks. The basic function of such systems is keeping and reproduction of units of time and frequency as well as generation continuous high-frequency signals with high stability and reliability characteristics. Producing of the output signals is generally performed by means of a small ensemble of active hydrogen masers [1]. In Russia ensembles of hydrogen masers are usually the basis of secondary and working time and frequency standards. In other countries ensembles of cesium frequency standards (based on a cesium atomic beam tube) or cesium and hydrogen atomic clocks both are often used [2].