Precision Packet-Based Frequency Transfer Based on Oversampling

Giorgi, Giada; Narduzzi, C.

doi:10.1109/tim.2017.2672478

Cited by 10 publications

(13 citation statements)

References 16 publications

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“…Other contributions propose alternative ways to perform the frequency synchronization and estimate the synchronization uncertainty. The former can be faced using oversampling method [29]. It requires a high rate exchange of timing packets reducing the available bandwidth for the applications and its timing performance can be affected in extreme conditions such as network congestion.…”

Section: White Rabbit Synchronization Protocolmentioning

confidence: 99%

A Fully Programmable White-Rabbit Node for the SKA Telescope PPS Distribution System

Jiménez-López

Torres-Gonzalez

Gutierrez-Rivas

et al. 2019

IEEE Trans. Instrum. Meas.

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Distributed data acquisition (DAQ) systems are in charge of converting different analog environment signals into digital values to perform control and monitor tasks. They require a computer network technology to share data between their different elements. One of their main issues is to match data with the specific events under study. A possible solution is to include an event synchronization technology such as Network Time Protocol (NTP), Precise Time Protocol (PTP), or White Rabbit (WR). This contribution proposes a high-performance distributed timing system based on the WR technology. We focus on the square kilometer array (SKA) project as an example of the distributed DAQ system. The SKA project has a strict timing requirements for its operation with a performance below 2 ns. This accuracy is not achievable by current standard synchronization technologies such as NTP or PTP. Under this context, the authors propose the WR zynq embedded node (WR-ZEN) platform as a candidate for the SKA's pulse per second (PPS) distribution system. It is a new design that integrates the WR technology, thus enabling the subnanosecond accuracy. Finally, the WR-ZEN has been evaluated in different scenarios to demonstrate its timing performance in dynamic environment conditions fulfilling the SKA telescope requirements for PPS distribution.

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Section: White Rabbit Synchronization Protocolmentioning

confidence: 99%

A Fully Programmable White-Rabbit Node for the SKA Telescope PPS Distribution System

Jiménez-López

Torres-Gonzalez

Gutierrez-Rivas

et al. 2019

IEEE Trans. Instrum. Meas.

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“…Exel et al [9] reported that the asymmetry of a link delay occurs by the different twist rates of the Ethernet cable pairs used for transmission and reception; thus, they configured links to ensure that the transmission path of the PTP packets used the same cable pairs. Giorgi et al [10] proposed software-based packet sampler with an oversampling strategy, which filters out packets with delays exceeding a certain value to reduce the possibility of asymmetry. The reliable range of packet delay is derived with the soft-min machine learning function and weight function defined by the Boltzmann distribution.…”

Section: Introductionmentioning

confidence: 99%

“…However, these previous works partially resolve the issue or introduce their own weaknesses. They require additional hardware supports [7], [11], [18], address only specific components of the total packet delay [7]- [9], [13], [21], [22], require additional or large amounts of packet exchanges [10]- [12], [20], or do not provide high accuracy at the nanosecond level [10], [12], [13], [19].…”

Section: Introductionmentioning

confidence: 99%

Clock Offset Estimation for Systems With Asymmetric Packet Delays

Pak

Park

et al. 2023

IEEE/ACM Trans. Networking

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This paper proposes a new clock offset estimation that mitigates unwanted link asymmetry for precise clock synchronization. The main contribution is to address the primary and traditional design issue of the IEEE 1588 standard precision time protocol (PTP), which estimates clock offset under the assumption that the delays of exchanged packets are symmetric. To mitigate the issue, we focus on the fact that PTP measures asymmetry variation through the derivatives of its timestamps with respect to the time step. By exploiting the measurement of the variation, the proposed approach defines the asymmetry in the form of a linear differential equation (LDE) and leverages the LDE to define and exclude asymmetry-induced errors. Additionally, we clearly derive the state transition of the asymmetry. Subsequently, we derive a novel state-space model from our approach. The model describes PTP clock offset estimation perfectly, allowing optimal clock offset estimation. We verify the theoretical validity of the proposed method with real data. Our approach improves PTP accuracy by more than thousand times and achieves an accuracy at the level of tens to hundreds of nanoseconds on an asymmetric communication link. Our approach realizes an accuracy comparable to that of PTPv2, without the cost of specialized hardware.

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“…Exel et al [5] reported that the asymmetry of a link delay occurs by the different twist rates of the Ethernet cable pairs used for transmission and reception; thus, they configured links to ensure that the transmission path of the PTP packets used the same cable pairs. Giorgi et al [6] proposed software-based packet sampler with an oversampling strategy, which filters out packets with delays exceeding a certain value to reduce the possibility of asymmetry. The reliable range of packet delay is derived with the soft-min machine learning function and weight function defined by the Boltzmann distribution.…”

Section: Introductionmentioning

confidence: 99%

“…However, these previous works partially resolve the issue or introduce their own weaknesses. They require additional hardware supports [3], [7], address only specific components of the total packet delay [3]- [5], [9], require additional packet exchanges [6]- [8], or do not provide high accuracy at the nanosecond level [6], [8], [9].…”

Section: Introductionmentioning

confidence: 99%

Clock Offset Estimation for Systems with Asymmetric Packet Delays

Ha¹,

Pak²,

Park³

et al. 2022

Preprint

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<p>This paper proposes a new clock offset estimation that mitigates unwanted link asymmetry for precise clock synchronization. The main contribution is to address the design issue of the IEEE 1588 standard precision time protocol (PTP), which estimates clock offset under the assumption that the delays of exchanged packets are symmetric. To mitigate the issue, we focus on the fact that PTP measures asymmetry variation through the derivatives of its timestamps with respect to the time step. By exploiting the measurement of the variation, the proposed approach defines the asymmetry in the form of a linear differential equation (LDE) and leverages the LDE to define and exclude asymmetry-induced errors. Additionally, we clearly derive the state transition of the asymmetry. Subsequently, we derive a novel state-space model from our approach. The model describes PTP clock offset estimation perfectly, allowing optimal clock offset estimation. We verify the theoretical validity of the proposed method with real data. Our approach improves PTP accuracy by more than thousand times and achieves an accuracy at the level of tens to hundreds of nanoseconds on an asymmetric communication link. Our approach realizes an accuracy comparable to that of PTPv2, without the cost of specialized hardware.</p>

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Precision Packet-Based Frequency Transfer Based on Oversampling

Cited by 10 publications

References 16 publications

A Fully Programmable White-Rabbit Node for the SKA Telescope PPS Distribution System

A Fully Programmable White-Rabbit Node for the SKA Telescope PPS Distribution System

Clock Offset Estimation for Systems With Asymmetric Packet Delays

Clock Offset Estimation for Systems with Asymmetric Packet Delays

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