Method and system for optimizing short-term stability of a clock

Abstract

A system for optimizing short-term stability of a clock from a clock source synchronized with a first reference clock source with long-term stability transmits numbers of clocks of a first reference clock from the first reference clock source (21, 22, 23, 24) to the clock source (8) between an initialization time and a plurality of times in each case in a data-packet-oriented network (9). The clock from the clock source (8) is adjusted by correcting a difference between numbers of clocks of the first reference clock which are received in the clock source (8) and numbers of clocks of the first reference clock between the initialization time and the respective times at which the numbers of clocks of the first reference clock are received. In addition, numbers of clocks of a second reference clock for the data packet are transmitted to the clock source (8) at individual times with the number of clocks from at least one second freewheeling reference clock source (111, 112). The maximum difference between the first reference clock and the second reference clock from the clock source (8) is known. The difference between the clock from the clock source (8) and each second reference clock is limited to a first adjustable threshold value.

Description

technical field [0001] The present invention relates to a method and system for optimizing the short-term stability of clock pulses. Background technique [0002] In networks, especially networks with high real-time requirements, e.g. For transmission in digital radio systems, the clock source used is synchronized with the reference-clock source. In this context, Global Positioning System (GPS) time, which is broadcast by GPS satellites as a high-precision time signal in one-second pulses (one pulse per second (PPS)) or in the form of a 10 MHz reference clock; or Network Time Protocol (NTP), which transmits reference time information in Coordinated Universal Time (UTC) time from NTP servers over a packet-oriented network, preferably over the Internet on demand by clients sending requests, are used as reference clock sources. [0003] Such as figure 1 shown, according to the secondary server 3 1 、3 2 、3 3 and 3 4 demand from master time server 1 1 ,1 2 ,1 3 and 1 4...

AI Technical Summary

Problems solved by technology

In the case of real-time applications at the head end, this can lead to overflow or zero loading of buffers in which individual packets of the digital transport stream to be transmitted are buffered, correspondingly loss of packets to be transmitted or transmission gaps Represents unacceptable operating conditions in various cases

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