Yu. A. Fedorov

Synchronizing the time and frequency standards at the Radio Astronomy Station, Physics Institute, USSR Academy of Sciences, with the state standard for time and frequency

The pulsar time scale [i, 2] is based on the pulsed radio emission from pulsars such as PSR 1937 + 214 (millisecond range), which imposes new requirements on the time service at the Radio Astronomy Station [3]. The standard deviation in the residual deviations in the time of arrival from the precalculated course is less than i Dsec [4]. In this connection, the error in the local time scale at the station should be less than I Dsec relative to that of the state standard of frequency and time in the USSR. For that purpose, the time and frequency service at the station has been equipped with high-stability quantum time and frequency standards and precision apparatus for matching them to the state scale.

Time scale lock-in using signals transmitted by Cuban television

In 1979 scientists of the USSR and the Cuban Republic devised a method of transmitting time signals through Cuban TV channels [i] whose distinctive feature is transmission of widthmodulated time pulses in the lOth line of the NTSC TV system. Experimental tests of the method proved that time signals with a repetition period of 1 msec once every second coincide with the 10th line interval allowed for transmission. The 10th line does not each time coincide with one and the same time signal as in the SECAM system but with each subsequent time pulse having a 1 msec repetition period. This means that i00 Hz signals are transmitted once every i0 sec and signals with a repetition frequency 1 Hz, once every i000 sec.

Improvement of the system for transmitting standard time and frequency signals over radio and TV channels

Methods of measuring time and frequency are widely used in various branches of science and engineering. In particular, these techniques are used in data compression in communication channels, navigation systems, and synchronous broadcasting. In such systems, it is necessary to provide synchronization in time and frequency for spatially separated time scales on the basis of the state standard of time and frequency (SSTF). Research and development work in recent years in the transmission of special time and frequency signals from the standard over various communication channels has gone in hand with the development of automatic receiving and synchronizing devices, which has opened up a new approach to the problem.

Methods of measuring signal transit times in television channels

ConclusionsThe transit time in the forward direction in an RRL containing a fixed type of equipment without regenerators can be measured with an error of 0.2 Μsec by means of the if loop with signal switching directly at the RRS terminal equipment and without the need for additional amplifiers.If the i.f loop is used, one also has to measure the delay in the frequency-detector channel by setting the equipment rack to feed itself at i.f. The time intervals between measurements of the transit interval along the RRL are determined by the periodicity of the maintenance operations involved on this line.

System for the simultaneous transmission of time signals and information as to the current time along television channels

Conclusions1.The system for transmitting time information along television channels provides most of the Soviet Union with exact time signals and information as to the current time by using transmission systems already in existence; as well as ensuring the high-accuracy matching of spatially-separated clocks, this leads to great economic efficiency.2.The apparatus for transmitting information regarding the current time may be used without serious changes in both short and longwave radio stations using present-day precision “second” signals, without interrupting the normal operation of the systems providing information as to the difference between the UT1 and UTC time scales (UT=universal time).

Automatic remote control system for the output time of television frame synchronizing pulses

Conclusions1.The use of a telephone line connecting the transmitting television center with the control point of the State Time and Frequency Service as a control channel makes it possible to match the output time of one of the frame synchronizing pulses (the edge of the first notch or the second pulse transmitted in the composite television signal) with the output time of the second pulses from a state standard clock to an error of ± 0.2μsec.2.The proposed design of a system to control the output time of frame synchronizing pulses makes it possible for users located in the reception area of the Moscow television transmitting center as well as users who receive the All-Union television broadcasting program over intercity and international cable and radio relay links to tie in local clocks without a reciprocal exchange of information with the central control point regarding the measured results.

Instrument for receiving automatically precise-time radio signals

ConclusionsThe device for the automatic locking-in of precise time signals uses a method based on a new principle for fixing these signals by their coincidence area with a rectangular gating pulse. The advantages of this method of forming input pulses in the automatic device as compared with recording the time signal at a given level of its leading edge has been shown [3].