Digital dual mixer time difference for sub-nanosecond time synchronization in Ethernet

Moreira, P; Alvarez, Pablo; Serrano, J.; Darwezeh, Izzat; Włostowski, Tomasz

doi:10.1109/freq.2010.5556289

Cited by 52 publications

(17 citation statements)

References 6 publications

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“…In the case considered, since f 0 = 125 MHz, a resolution in the order of a few picoseconds is needed, which is quite challenging. In principle, this problem can be solved by using a DDMTD approach [34]. The basic idea of this method (which was originally proposed in [42]) consists in down-converting a signal by mixing it with a stable periodic waveform having a slightly smaller frequency.…”

Section: Methodsmentioning

confidence: 99%

“…In the scenario described in this paper and shown in Fig. 1, first the phases of N available input signals are measured, e.g., by means of a digital dual mixer time difference (DDMTD) approach, as described in Section V [34]. Then, possible outliers due to sudden and large frequency changes are detected and removed, thus improving estimation robustness in case of unexpected events such as cable disconnections or node failures.…”

Section: Sharing Time and Frequency In Distributed Systemsmentioning

confidence: 99%

See 1 more Smart Citation

Enhancing Accuracy and Robustness of Frequency Transfer Using Synchronous Ethernet and Multiple Network Paths

Rizzi

Rinaldi

Ferrari

et al. 2016

IEEE Trans. Instrum. Meas.

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Distributed measurement and control systems often rely on time synchronization protocols over Ethernet. Recently, it has been shown that estimating and compensating for not only time offsets, but also frequency skews is of crucial importance to meet the accuracy requirements of high-end applications. In this respect, this paper presents a new technique capable of: 1) measuring the jitter of multiple reference signals received by a single node over different network paths and 2) combining them in order to synthesize a downstream signal with a more stable frequency than using a single reference. The proposed algorithm can exploit the native frequency transport of Synchronous Ethernet and relies on a module for outlier identification and removal, a Kalman filter, and a linear quadratic regulator that drives a local voltage-controlled oscillator. The algorithm performance has been evaluated through both simulations and experiments using a prototype platform based on a field-programmable gate array. Simulation and experimental results confirm that the proposed approach can strongly decrease the jitter and wander of the generated signal. For instance, the time deviation is reduced on average by about 30% when three stable input references are merged and by several orders of magnitude when one of the input signals is affected by a large frequency step.

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Section: Methodsmentioning

confidence: 99%

Section: Sharing Time and Frequency In Distributed Systemsmentioning

confidence: 99%

Enhancing Accuracy and Robustness of Frequency Transfer Using Synchronous Ethernet and Multiple Network Paths

Rizzi

Rinaldi

Ferrari

et al. 2016

IEEE Trans. Instrum. Meas.

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show abstract

“…Nonetheless, to achieve the specified sub-nanosecond timing accuracy, the network clock recovered at the slave node is used as clock reference to transmit data from the slave to the master node. At the master node the phase difference between the master clock and the recovered network clock is being monitored by a Digital Dual Mixer Time Difference (DDMTD) [8] circuit. The phase difference measured by the DDMTD is transmitted to the slave nodes to compensate for phase variations and to phase align the slave clocks with the master clock.…”

Section: White Rabbit Networkmentioning

confidence: 99%

Distributing RF signals in an Ethernet network

Moreira

Serrano²,

Alvarez³

et al. 2012

2012 IEEE International Frequency Control Symposium Proceedings

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In this paper, a system architecture designed to distribute radio frequency (RF) signals in an Ethernet-based network is proposed. The Ethernet is the physical layer of the White Rabbit (WR) network. The WR network aims to distribute timing signals with sub-nanosecond accuracy. It is based on the IEEE 1588 and Synchronous Ethernet standards to allow rapid deployment for a broad range of applications. The input RF signal is digitally processed to minimize the required network bandwidth necessary to transport it. Simulations are presented in this paper that show how the different system parameters affect amplitude noise and timing jitter in the distributed RF signal.

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“…One possible approach for the measurement of phase differences that avoids these issues is the Digital Dual-Mixer Time Difference (DDMTD) method, first proposed in [125] for a laser range finding application, and then adapted to the White Rabbit time synchronization scheme by Moreira et al [126]. This circuit is linear over the full phase range with no dead zone and only requires digital gates and a PLL, which can be found in virtually all modern FPGAs.…”

Section: Phase Measurementmentioning

confidence: 99%

“…The first analysis of the uncertainty in DDMTD phase estimates was published in [126] and expanded in [128], in the simplest case of sequence 01, i.e. simple rising edges.…”

Section: Uncertainty In Ddmtd Measurementmentioning

confidence: 99%

Development of a data acquisition architecture with distributed synchronization for a Positron Emission Tomography system with integrated front-end.

Varea¹,

Ramón²

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Positron Emission Tomography (PET) is a non-invasive nuclear medical imaging modality that makes it possible to observe the distribution of metabolic substances within a patient's body after marking them with radioactive isotopes and arranging an annular scanner around him in order to detect their decays. The main applications of this technique are the detection and tracing of tumors in cancer patients and metabolic studies with small animals.The Electronic Design for Nuclear Applications (EDNA) research group within the Instituto de Instrumentación para Imagen Molecular (I3M) has been involved in the study of high performance PET systems and maintains a small experimental setup with two detector modules. This thesis is framed within the necessity of developing a new data acquisition system (DAQ) for the aforementioned setup that corrects the drawbacks of the existing one. The main objective is to define a DAQ architecture that is completely scalable, modular, and guarantees the mobility and the possibility of reusing its components, so that it admits any extension of modification of the setup and it is possible to export it directly to the configurations used by other groups or experiments. At the same time, this architecture should be compatible with the best possible resolutions attainable at the present instead of imposing artificial limits on system performance. In particular, the new DAQ system should outperform the previous one.As a first step, a general study of DAQ architectures is carried out in the context of experimental setups for PET and other high energy physics applications. On one hand, the conclusion is reached that the desired specifications require early digitization of detector signals, exclusively digital communication between modules, and the absence of a centralized trigger. On the other hand, the necessity of a very precise distributed synchronization scheme between modules becomes apparent, with errors in the order of 100 ps, and operating directly over the data links. A study of the existing methods reveals their severe limitations in terms of achievable precision. A theoretical analysis of the situation is carried out with the goal of overcoming them, and a new synchronization algorithm is proposed that is able to reach the desired resolution while getting rid of the restrictions on clock iii alignment that are imposed by virtually all usual schemes. Since the measurement of clock phase difference plays a crucial role in the proposed algorithm, extensions to the existing methods are defined and analyzed that improve them significantly. The proposed scheme for synchronism is validated using commercial evaluation boards.Taking the proposed synchronization method as a starting point, a DAQ architecture for PET is defined that is composed of two types of module (acquisition and concentration) whose replication makes it possible to arrange a hierarchic system of arbitrary size, and circuit boards are designed and commissioned that implement a realization of the architecture for the...

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Digital dual mixer time difference for sub-nanosecond time synchronization in Ethernet

Cited by 52 publications

References 6 publications

Enhancing Accuracy and Robustness of Frequency Transfer Using Synchronous Ethernet and Multiple Network Paths

Enhancing Accuracy and Robustness of Frequency Transfer Using Synchronous Ethernet and Multiple Network Paths

Distributing RF signals in an Ethernet network

Development of a data acquisition architecture with distributed synchronization for a Positron Emission Tomography system with integrated front-end.

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