Distribution of standard frequency and time signals

This paper reviews the present methods of distributing standard frequency and time signals (SFTS), which include the use of high-frequency, low-frequency, and very-low-frequency radio signals, portable clocks, satellites, and RF cables and lines. The range of accuracies attained with most of these systems is included along with an indication of the sources of error. Information is also included on the accuracy of signals generated by frequency dividers and multipliers. Details regarding the techniques, the propagation media, and the equipment used in the distribution systems described are not included. Also, the generation of the signals is not discussed.