Time server is a device that can receive Beidou, GPS, GLONASS and other satellite signals, and can rely on satellite positioning signals to provide time service. At present, the time server has the equipment to receive single satellite signals, and also has the equipment to receive many kinds of satellite signals. And there are many ways of their time service, such as serial port time service, IRIG-B code time service, NTP network time service, 1PPS pulse timing, PTP timing, CDMA time service and so on.

Under the rapid progress and development of science and technology, various fields are constantly advancing and changing, and there are more and more demands for time service equipment, such as the accuracy, stability and portability of time servers. The time server time service mode is generally based on NTP network timing. It is convenient and efficient in timing, and can provide time to 10000 devices. However, the lack of hardware support is not enough for NTP network to provide time. The accuracy is not high enough to reach milliseconds, which can not well satisfy modern industrial control. Such as power industry, rail transit and other applications with high precision requirements, while the PTP master clock equipment has been improved by PTPV2 and IEEE1588-2008 protocol, and the timing accuracy has been improved to nanosecond level. The IEEE 1588 standard is called "precision clock synchronization protocol standard of network measurement and control system" or "PTP" for short.

Therefore, some industries choose the timing method of PTP according to their different usage environment or different timing accuracy. PTP time service is also a common way of timing. PTP is IEEE 1588 for short (PTP, picture transfer). Protocol) is a standardized precise time protocol, which defines an accurate clock synchronization protocol in the measurement and control system, which is related to network communication, local computation and allocation of objects. This protocol is applicable to any distributed control system that satisfies multi-point communication, and can achieve substandard synchronization for the terminals using multicast technology terminals and achieve higher accuracy.

PTP timing principle, PTP timing clock can realize the function of master clock and slave clock, but there is only one master clock in a PTP communication subnet. PTP timing equipment SYN2401PTP precision master clock receives GPS satellite signal output PTP time information, and then SYN2403PTP precision timing clock card from the clock and SYN2407PTP synchronous clock, receives the time information sent by the main clock, then transfers the time information from the clock to B code and serial port. Based on this information, the system calculates the time delay and master-slave time difference between the master and slave lines, and adjusts the local time with this time difference, so that the time information of the terminal equipment is consistent with the device time information of the PTP master clock, and the time synchronization in the local area network is realized.

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