Timing Signals and Radio Frequency Distribution Using Ethernet Networks for High Energy Physics Applications

Timing networks are used around the world in various applications from telecommunications systems to industrial processes, and from radio astronomy to high energy physics. Most timing networks are implemented using proprietary technologies at high operation and maintenance costs. This thesis presents a novel timing network capable of distributed timing with subnanosecond accuracy. The network, developed at CERN and codenamed “White- Rabbit”, uses a non-dedicated Ethernet link to distribute timing and data packets without infringing the sub-nanosecond timing accuracy required for high energy physics applications. The first part of this thesis proposes a new digital circuit capable of measuring time differences between two digital clock signals with sub-picosecond time resolution. The proposed digital circuit measures and compensates for the phase variations between the transmitted and received network clocks required to achieve the sub-nanosecond timing accuracy. Circuit design, implementation and performance verification are reported. The second part of this thesis investigates and proposes a new method to distribute radio frequency (RF) signals over Ethernet networks. The main goal of existing distributed RF schemes, such as Radio-Over-Fibre or Digitised Radio-Over-Fibre, is to increase the bandwidth capacity taking advantage of the higher performance of digital optical links. These schemes tend to employ dedicated and costly technologies, deemed unnecessary for applications with lower bandwidth requirements. This work proposes the distribution of RF signals over the “White-Rabbit” network, to convey phase and frequency information from a reference base node to a large numbers of remote nodes, thus achieving high performance and cost reduction of the timing network. Hence, this thesis reports the design and implementation of a new distributed RF system architecture; analysed and tested using a purpose-built simulation environment, with results used to optimise a new bespoke FPGA implementation. The performance is evaluated through phase-noise spectra, the Allan-Variance, and signalto- noise ratio measurements of the distributed signals

Development and testing of a dual accelerometer vector sensor for AUV acoustic surveys

This paper presents the design, manufacturing and testing of a Dual Accelerometer Vector Sensor (DAVS). The device was built within the activities of theWiMUST project, supported under the Horizon 2020 Framework Programme, which aims to improve the efficiency of the methodologies used to perform geophysical acoustic surveys at sea by the use of Autonomous Underwater Vehicles (AUVs). The DAVS has the potential to contribute to this aim in various ways, for example, owing to its spatial filtering capability, it may reduce the amount of post processing by discriminating the bottom from the surface reflections. Additionally, its compact size allows easier integration with AUVs and hence facilitates the vehicle manoeuvrability compared to the classical towed arrays. The present paper is focused on results related to acoustic wave azimuth estimation as an example of its spatial filtering capabilities. The DAVS device consists of two tri-axial accelerometers and one hydrophone moulded in one unit. Sensitivity and directionality of these three sensors were measured in a tank, whilst the direction estimation capabilities of the accelerometers paired with the hydrophone, forming a vector sensor, were evaluated on a Medusa Class AUV, which was sailing around a deployed sound source. Results of these measurements are presented in this paper.European Union [645141]info:eu-repo/semantics/publishedVersio

Electronic Components and Systems for the Control of the LHC Machine

The present estimation of the LHC underground control electronics gives a total of 10.400 crates of which some 4.400 will be connected to the machine control network. Electronic equipment will be housed under the cryostats, along the tunnel, in the alcoves and in the galleries parallel to the machine tunnel. In the regular arcs and in the dispersion suppressers areas the radiation level is expected to be relatively low. But, despite this low radiation level, radiation tests results obtained in previous years demonstrate that all electronic equipment needs to be qualified in a test facility providing an LHC like radiation environment. The radiation qualification of all tunnel electronics is essential in order to guaranty a reliable operation over the lifetime of the machine. The object of this paper is to give a review of the various electronic systems as they are planned today and to provide simulation results concerning the radiation environment of the CERN on-line test facility used for qualification of electronic component and systems. This paper is an update and an extension of the presentation made at the 5th Workshop on Electronics for LHC Experiments held in Snowmass in September 1999

Low-Power Mixed-Signal ASIC for Cryogenic SiPM Readout

L'abstract è presente nell'allegato / the abstract is in the attachmen

An instrumentation system for the measurement and display of the dynamic force distribution under the foot during locomotion

Bibliography: pages 81-83.The clinical assessment of the weight bearing foot during locomotion is normally based on subjective judgement rather than on quantitative measurement. The techniques which have been proposed for recording the dynamic forces acting on the foot are either too complex for clinical practise or there is difficulty in relating the measured force distribution to the physical surface of the foot. The system that has been developed measures the vertical foot/ground forces during gait and immediately displays the data in a manner which can be readily assimilated. The instrumentation system consists of a segmented force plate constructed from 16 transparent beams mounted so that the total load as well as the centre of pressure on any beam can be ascertained. When the foot contacts the plate, its plantar surface is photographed through the transparent force plate by a television camera while a second television camera photographs a lateral aspect of the legs and feet. A composite video display is then generated consisting of (i) a lateral view of the legs and feet (ii) a view of the plantar surface of the planted foot with centre of pressure lines superimposed (iii) a bar chart display of the load carried by each beam. The system output is recorded on a video tape recorder which has a stop motion facility. This enables a frame by frame analysis to be made subsequently and selected stills to be photographed as a permanent record. Three series of photographs are presented which clearly show the differences between normal and abnormal gait

Power conversion for a modular lightweight direct-drive wind turbine generator

A power conversion system for a modular lightweight direct-drive wind turbine generator has been proposed, based on a modular cascaded multilevel voltage-source inverter. Each module of the inverter is connected to two generator coils, which eliminates the problem of DC-link voltage balancing found in multilevel inverters with a large number of levels.The slotless design of the generator, and modular inverter, means that a high output voltage can be achieved from the inverter, while using standard components in the modules. Analysis of the high voltage issues shows that isolating the modules to a high voltage is easily possible, but insulating the generator coils could result in a signicant increase in the airgap size, reducing the generator effciency. A boost rectier input to the modules was calculated to have the highest electrical effciency of all the rectier systems tested, as well as the highest annual power extraction, while having a competitive cost. A rectier control system, based on estimating the generator EMF from the coil current and drawing a sinusoidal current in phase with the EMF, was developed. The control system can mitigate the problem of airgap eccentricity, likely to be present in a lightweight generator. A laboratory test rig was developed, based on two 2.5kW generators, with 12 coils each. A single phase of the inverter, with 12 power modules, was implemented, with each module featuring it's own microcontroller. The system is able to produce a good quality AC voltage waveform, and is able to tolerate the fault of a single module during operation. A decentralised inverter control system was developed, based on all modules estimating the grid voltage position and synchronising their estimates. Distributed output current limiting was also implemented, and the system is capable of riding through grid faults

Monitoring of Energy Data with Seamless Temporal Accuracy Based on the Time-Sensitive Networking Standard and Enhanced μPMUs

In the energy sector, distributed synchronism and a high degree of stability are necessary for all real-time monitoring and control systems. Instantaneous response to critical situations is essential for the integration of renewable energies. The most widely used standards for clock synchronisation, such as Network Time Protocol (NTP) and Precision Time Protocol (PTP), do not allow for achieving synchronised simultaneous sampling in distributed systems. In this work, a novel distributed synchronism system based on the Time-Sensitive Networking (TSN) standard has been validated for its integration in an architecture oriented towards the high-resolution digitisation of photovoltaic (PV) generation systems. This method guarantees a time stamping with an optimal resolution that allows for the analysis of the influence of fast-evolving atmospheric fluctuations in several plants located in the same geographical area. This paper proposes an enhanced micro-phasor measurement unit (μPMU) that acts as a phasor meter and TSN master controlling the monitoring system synchronism. With this technique, the synchronism would be extended to the remaining measurement systems that would be involved in the installation at distances greater than 100 m. Several analyses were carried out with an on-line topology of four acquisition systems capturing simultaneously. The influence of the Ethernet network and the transducers involved in the acquisition process were studied. Tests were performed with Ethernet cable lengths of 2, 10, 50, and 75 m. The results were validated with 24-bit Sigma-Delta converters and high-precision resistor networks specialised in high-voltage monitoring. It was observed that with an appropriate choice of sensors and TSN synchronism, phase errors of less than ±1μs can be guaranteed by performing distributed captures up to 50 kS/s. Statistical analysis showed that uncertainties of less than ±100 ns were achieved with 16-bit Successive Approximation Register (SAR) converters at a moderate cost. Finally, the requirements of the IEEE C37.118.1-2011 standard for phasor measurement units (PMU) were also satisfied. This standard establishes an uncertainty of ±3.1 μs for 50 Hz systems. These results demonstrate the feasibility of implementing a simultaneous sampling system for distributed acquisition systems coordinated by a μPMU

THE APPLICATION OF REAL-TIME SOFTWARE IN THE IMPLEMENTATION OF LOW-COST SATELLITE RETURN LINKS

Digital Signal Processors (DSPs) have evolved to a level where it is feasible for digital modems with relatively low data rates to be implemented entirely with software algorithms. With current technology it is still necessary for analogue processing between the RF input and a low frequency IF but, as DSP technology advances, it will become possible to shift the interface between analogue and digital domains ever closer towards the RF input. The software radio concept is a long-term goal which aims to realise software-based digital modems which are completely flexible in terms of operating frequency, bandwidth, modulation format and source coding. The ideal software radio cannot be realised until DSP, Analogue to Digital (A/D) and Digital to Analogue (D/A) technology has advanced sufficiently. Until these advances have been made, it is often necessary to sacrifice optimum performance in order to achieve real-time operation. This Thesis investigates practical real-time algorithms for carrier frequency synchronisation, symbol timing synchronisation, modulation, demodulation and FEC. Included in this work are novel software-based transceivers for continuous-mode transmission, burst-mode transmission, frequency modulation, phase modulation and orthogonal frequency division multiplexing (OFDM). Ideal applications for this work combine the requirement for flexible baseband signal processing and a relatively low data rate. Suitable applications for this work were identified in low-cost satellite return links, and specifically in asymmetric satellite Internet delivery systems. These systems employ a high-speed (>>2Mbps) DVB channel from service provider to customer and a low-cost, low-speed (32-128 kbps) return channel. This Thesis also discusses asymmetric satellite Internet delivery systems, practical considerations for their implementation and the techniques that are required to map TCP/IP traffic to low-cost satellite return links