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.

Timing and Synchronization over Ethernet

Abstract: In this thesis an investigation will be done on how time and frequency can be synchronized over Ethernet with help of Precision Time Protocol and Synchronous Ethernet. The goal is to achieve a high accuracy in the synchronization when a topology of 10 cascaded nodes is used. Different approaches may be used when implementing Precision Time Protocol for synchronization. They will be investigated and the best approach for a good accuracy will be proposed. Another question that this thesis will cover is how to recover a radio frequency, a multiple of 3.84 MHz from Ethernets 10.3125 GHz.By using hardware support for the timestamps and transparent clocks in the forwarding nodes the best accuracy is achieved for the time and phase synchronization. Combining this with Synchronous Ethernet for frequency synchronization, to get a traceable clock through the system, will lead to the best result. The total error does not need to be greater than 1.46~ns if the asymmetry in the medium is neglected and a welldesigned PCS and FIFO are used. Recovering the radio frequency from Ethernet is done by using the highest common frequency, either an integer phase locked loop or a fractional phase locked loop can be used. The fractional phase locked loop will give a better result but will contribute with spurs that the integer phase locked loop does not.

IEEE1588 V2 clock distribution in FlexRIO devices: clock drift measurement

Abstract: Abstrac t -Instrumentation in scientific experiments requires highest accurate to correlate acquired data with a time reference. In order to implement data acquisition channels synchronized to a reference clock, it is necessary to deploy a distributed clock based on computer devices with specific hardware for data acquisition, and to use a technology capable of synchronizing every computer in the system. Although there are several technologies to synchronize devices as the Precision Time Protocol (PTP) IEEE1588 V2 [1], not always is trivial to use it to get a good performance. This work studies how can be used the drift measures between clocks to get them synchronized. The solution has been implemented using a PTP-clock (implemented in a IEEE1588 PXI device), to every PXI/PXIe [2] and the FPGA based FlexRIO devices [3], able to reconfigure its hardware. The PXI/PXIe bus will be the key element to propagate the clock from the timing board to every RIO/FlexRIO card, achieving to phase their internal clocks with the PTP.

Method and device for implementing rapid synchronous switching in PTP (precision time protocol)

Abstract: The invention discloses a method and a device for implementing rapid synchronous switching in a PTP (precision time protocol). A plurality of clock examples are arranged on clock PTP equipment and a plurality of synchronous interfaces are configured, so that the synchronous interfaces are connected with main clocks and a clock synchronous information processing module, the clock synchronous information processing module receives the information of the main clocks through the synchronous interfaces, the synchronous relations between the plurality of main clocks and the clock examples are built, the best clock example is selected from all the clock examples through a clock output module to be output to be used as a current system, and if the synchronous relation of the selected clock example is changed, the clock output module is immediately switched to another clock example to be output. According to the method and the device for implementing rapid synchronous switching in the PTP, the synchronous convergence time of the clocks is improved, the clocks are rapidly synchronously switched, and the reliability of the PTP is improved.

Research of time synchronization in ECT/EVT of intelligent substation IEEE1588-based

Abstract: The application of electronic transformer brings sampling time synchronization problem, this paper introduces the IEEE1588 which is Precision Time Protocol (PTP) into the synchronization time electric power system. This paper gives the principle of IEEE1588, analyzes the influence factors of the clock synchronization and two solutions. Based on the synchronization of electronic transformers currently, a new high precision synchronization based on the IEEE1588 Protocol is proposed. At last, the value and effectiveness of the synchronization is summarized.

A system for transmitting low latency, synchronised audio

Abstract: A system for transmitting low latency, synchronised audio includes an audio source, a processor, a controller and a sink zone with a DAC. The processor selectively resamples the audio source in order to output a data packet for transmission to the sink zone that has a maximised payload size while packet frequency remains a whole number. In an embodiment the audio source is a CD player and the audio is upsampled from 44.1 kHz to 48 kHz. The resulting data packet has 128 frames, a payload size of 594 bytes, a packet frequency of 375Hz, and is smaller than the maximum transmission unit (MTU) (see table 2 on page 7). The audio output is transmitted using the Internet Protocol (IP) and is based on UDP Multicast and point-to-point UDP and TCP. A common time clock is implemented across the DACs of sink zones using Network Time Protocol (NTP) or Precision Time Protocol (PTP), and each packet carries a presentation time (fig. 3).