Precision Time Protocol

About: Precision Time Protocol is a research topic. Over the lifetime, 604 publications have been published within this topic receiving 6006 citations. The topic is also known as: PTP & IEEE 1588.

High-precision network clock server of LTE (Long Term Evolution) system

Abstract: The utility model discloses a high-precision network clock server of an LTE (Long Term Evolution) system, which comprises a three-in-one satellite receiving unit, a 1588 clock interface unit and a local clock signal generating unit. The three-in-one satellite receiving unit is used for automatically selecting to receive any one effective satellite clock input signal in a GPS (Global Positioning System), a BeiDou satellite or a GLONASS (GLObal NAvigation Satellite System); the 1588 clock interface unit is used for acquiring a 1588 clock input signal; the local clock signal generating unit is used for generating a local clock signal according to the satellite clock input signal or the 1588 clock input signal and outputting the local clock signal to output interfaces; and the output interfaces comprise 10MHz, E1, PTP (Precision Time Protocol), 1PPS (Pulse Per Second)+TOD (Time Of Date) and IRIG-B (InterRange Instrumentation Group B) interfaces. The high-precision network clock server has the capacity of automatically switching among three satellite systems and supports to use a PTP input as a clock reference source; the clock source can be provided for the system under the condition that the three-in-one satellite receiving unit goes wrong; and the reliability of the operation of the system is greatly improved.

Towards Robust Synchronization in IoT Networks

Abstract: With the increasing deployment of large-scale distributed sensors and associated networks in the industrial IoT systems, highly reliable and precise clock synchronization gains ever increasing importance to ensure timeliness of the exchanged datagrams. While GPS (Global Position System), PTP (Precision Time Protocol) and NTP (Network Time Protocol) are prominent synchronization schemes, there are disadvantages in terms of accuracy achieved, hardware required, scalability, cost and associated failure modes. There is a need of robust, cost effective, scalable, easy to deploy, maintain and yet accurate synchronization method especially for IoT systems. This work focuses on implementation and validation of synchronization scheme using Kalman filter for IoT applications. The algorithm was implemented on a industrial platform for validation. The performance was assessed for its suitability in IoT based robust synchronization systems. The results show that the proposed approach and implementation is a promising candidate for synchronization in current and future IoT applications. The proof of concept confirms the feasibility of software only synchronization systems for IoT.

Method for setting security authentication in precision time protocol (PTP)

Abstract: The invention discloses a method for setting security authentication in a precision time protocol (PTP). The method comprises the following steps of: setting keys on a time synchronous source and time synchronous equipment in advance, and adding an identity authentication field in the transmitted PTP message when the time synchronous source transmits synchronous information to the time synchronous equipment, wherein the field comprises a first MD5 value, and the MD5 value consists of a sequence ID field and key logic operation; performing corresponding logic operation on the sequence ID field in the message and a locally preset key when the time synchronous equipment receives the PTP message to obtain a second MD5 value; comparing the two MD5 values, passing the PTP authentication if the PTP messages are the same, otherwise discarding the messages. Thus, the communication safety of PTP is guaranteed, so that equipment for operating the PTP is hardly influenced by hostile attack from an internet.

Sub-nanosecond Synchronization over 1G ethernet data links using white rabbit technologies on the WR-ZEN board

Abstract: The White Rabbit (WR) technology has been introduced as an enhancement and next generation of the Precision Time Protocol (PTP, IEEE 1588), providing a boost in synchronization accuracy from the usual sub-microsecond range commonly found in PTPv2-based applications, down to the much more precise sub-nanosecond range. A number of White Rabbit-capable network nodes have been developed with the goal of allowing simultaneous deterministic time transfer and regular Ethernet data traffic to coexist on the same link without significant performance degradation over fiber links spanning tens of kilometers. The first SoC-based platform amongst these nodes is the WR-ZEN board, which implements a real-time White Rabbit stack in the Programmable Logic (PL) of the Zynq-7000 SoC; and features a hardened, ARM dual-core Processing System (PS) for running an embedded Linux environment. This paper presents the work carried out to upgrade the WR-ZEN board implementation, whose peak data throughput is limited just below 70 Mbps, so that a 1 Gbps data rate can be attained without impacting the performance of the White Rabbit synchronization. This goal is fulfilled by designing additional custom logic based on the Xilinx AXI DMA core, as well as an updated Linux network driver. This enhancement allows the widespread deployment of the WR-ZEN for major scientific infrastructure projects that require high-speed data transmission and deterministic timing transfer, as is the case of telescope arrays. Lastly, experimental results are presented comparing the synchronization performance of a baseline PTP-based setup to that achieved on the enhanced WR-ZEN board in the presence of high throughput data traffic. Conclusions are drawn and potential scientific and industrial applications that tap this increased bandwidth with deterministic timing transfer are discussed.

Nanoseconds Timing System Based on IEEE 1588 FPGA Implementation

Abstract: Clock synchronization procedures are mandatory in most physical experiments where event fragments are readout by spatially dislocated sensors and must be glued together to reconstruct key parameters (e.g. energy, interaction vertex etc.) of the process under investigation. These distributed data readout topologies rely on an accurate time information available at the frontend, where raw data are acquired and tagged with a precise timestamp prior to data buffering and central data collecting. This makes the network complexity and latency, between frontend and backend electronics, negligible within upper bounds imposed by the frontend data buffer capability. The proposed research work describes an FPGA implementation of IEEE 1588 Precision Time Protocol (PTP) that exploits the CERN Timing, Trigger and Control (TTC) system as a multicast messaging physical and data link layer. The hardware implementation extends the clock synchronization to the nanoseconds range, overcoming the typical accuracy limitations inferred by computers Ethernet based Local Area Network (LAN). Establishing a reliable communication between master and timing receiver nodes is essential in a message-based synchronization system. In the backend electronics, the serial data streams synchronization with the global clock domain is guaranteed by an hardware-based finite state machine that scans the bit period using a variable delay chain and finds the optimal sampling point. The validity of the proposed timing system has been proved in point-to-point data links as well as in star topology configurations over standard CAT-5e cables. The results achieved together with weaknesses and possible improvements are hereby detailed.