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621.396.96The design principles and advantages of a phase radiometeoric apparatus for comparing time scales are considered. The principal characteristics are presented together with the results of tests of samples.The radiometeoric method of comparison, along with methods utilizing transportable quantum clocks and artificial satellite radio navigation systems (GPS, GLONASS), presently provides a comparison error of the order of tens of nanoseconds. The radiometeoric method of comparison exceeds these methods in terms of such parameters as the measurement productivity, self-sufficiency, operating efficiency, economy, security, and stability against ionospheric perturbations.In 1986 a radiometeoric system was completed for comparing the Ukrainian and Russian standards. It was equipped with Metka-6 facilities [1, 2] developed in Kharkov (KhTURI~). Two generations of industrial apparatus were developed at the Russian Institute of Radio Navigation and Time jointly with KhTUR.E and Kazan University. Improved versions of the apparatus having errors of less than 10 nsec (Metka-8, Faza, Metka-ll) [3, 4] were developed and tested at KIaTURE.At present, in accordance with an Agreement on the Collaboration of the CIS Countries in providing traceability of time and frequency measurements (Bishkek, October 9, 1992), regular comparisons are being made on the Kharkov to Moscow path. A modified version Metka-6M of the apparatus compatible with the radiometeoric comparison system facilities (Metka-5, Metka-6) was developed and introduced at KhTURI~ for the Kiev station (UkrTsSM). Processing, storage, and output of the measured results in the Metka-6M facility are provided using a computer [5].Investigations of the accuracy characteristics of the meteor channel and of signal and apparatus errors made in recent years, and the results of analyzing and synthesizing comparison algorithms, have shown that the possibilities of the method are far from exhausted [4]. One of the most promising approaches to improving radiometeoric comparison systems is the use of phase principles of apparatus design.The possibility of utilizing phase measurement principles for radiometeoric comparison systems appeared after obtaining confidence estimates for the short-time phase instability of signal delays in a radiometeoric channel [6]. This instability, estimated from the rate of change of the delays 12 r = dz/dt, was investigated using the results of phase measurements at the carrier and difference frequencies of a coherent two-frequency signal of the Faza facility developed at Kharkov The maximum values of [ Vr [ were (1-2).10 -6 and (5-7)-10 -7 respectively. The distribution law of I f~r was close to exponential. In (5-10)% of cases there were considerable differences in V 7 for different frequencies and facilities. This can be explained by the irreversibility of the delay of signals for individual meteor trails.An analysis of the theoretical and experimental investigations of the sources of nonreciprocity of channel delay (polarization phenomena dur...