上海光源数字化束流位置信号处理器测试平台研制

数字化束流位置信号处理器(Digital Beam Position Monitor Processor,DBPM)是上海光源自主研发作为束流位置监测(Beam Position Monitor,BPM)的主要设备。针对DBPM电子学处理器产品化测试需求开发了一套基于MATLAB和程控技术的自动化测试平台,用于处理器批量测试验收和性能评估。平台使用Agilent MXG信号源和一分四功分器模拟4路真实探头信号,经过处理器采集处理后被上位机接收。测试仪器的设置和实验数据的获取,整个系统是基于客户端和服务器架构实现的。采用物理实验与工业控制系统(Experimental Physics and Industrial Control System,EPICS)的通道访问Lab CA接口实现数据的实时采集。目前该测试平台已经成功应用于大连自由电子激光装置和上海软X射线自由电子激光装置的DBPM处理器验收测试,处理器幅频响应曲线,不同衰减下模数变换器(Analog to Digital Converter,ADC)噪声水平测试、衰减步长一致性、通道间串扰及信噪比测试结果均达到设计指标。     

加速器数字束流位置测量系统数控振荡器设计

有鉴于高品质NCO是数字BPM系统重要设计内容之一,利用CORDIC完成了NCO的设计与实现,内容包括NCO参数的设计,系统框架设计、控制流程设计、结果检验和资源占用情况分析等。结果检验是在XC5VSX95T硬件平台上利用Chip Scope工具来完成的。结果表明,该方法能够有效设计出满足数字BPM系统需求的NCO,并在束流位置测量系统建设中发挥积极作用。     

DBPM signal processing with field programmable gate arrays

DBPM system performance is determined by the design and implementation of beam position signal processing algorithm.In order to develop the system,a beam position signal processing algorithm is implemented on FPGA.The hardware is a PMC board ICS-1554A-002(GE Corp.)with FPGA chip XC5VSX95T.This paper adopts quadrature frequency mixing to down convert high frequency signal to base.Different from conventional method,the mixing is implemented by CORDIC algorithm.The algorithm theory and implementation details are discussed in this paper.As the board contains no front end gain controller,this paper introduces a published patent-pending technique that has been adopted to realize the function in digital logic.The whole design is implemented with VHDL language. An on-line evaluation has been carried on SSRF(Shanghai Synchrotron Radiation Facility)storage ring.Results indicate that the system turn-by-turn data can measure the real beam movement accurately,and system resolution is 1.1μm.     

Implementation and integration of a systematic DBPM calibration with PLL frequency synthesis and FPGA

Beam current dependence resulted from nonlinearity and asymmetry of the four channels of digital BPM(Beam Position Monitor) processor deteriorates the BPM performance.A systematic solution based on signal source calibration tactics has been carried out to rectify this defect.It is optimized for implementation in FPGA.Mathematical illustrations of the calibration method,hardware and software design and implementation are presented.A signal source circuit using frequency synthesis technique is designed as calibration standard.Data acquisition system using JAVA web technology and Ethernet is introduced.Integrated FPGA implementation code architecture is presented,and experimental test results show that the method implemented in FPGA is feasible.Compared to other methods,our approach can rectify the nonlinearity and asymmetry simultaneously.The whole solution is integrated into the DBPM processor and can be executed online.     

A new digital beam position monitor in SSRF

The newly developed Digital Beam Position Monitor (DBPM) system is introduced. The DBPM system differs with the conventional beam position monitor system in the use of DSP chips and the digital signal processing technology. It can be programmed on-line to select operation modes through EPICS control panel, and to measure various parameters of the third generation synchrotron radiation facility. This DBPM system can be used in the pre-injector LINAC, the transfer lines, the booster synchrotron and the storage ring. The electronic parameters of the DBPM system itself have been measured also.     

Beam test results of high Q CBPM prototype for SXFEL

In pursuit of high-precision beam position measurements at micrometers or submicrometers for the Shanghai soft X-ray free-electron laser (SXFEL) facility which is under construction in the vicinity of the Shanghai Synchrotron Radiation Facility,a high Q cavity beam position monitor (CBPM) with a resonant frequency of 4.7 GHz is developed by the Shanghai Institute of Applied Physics,and the relevant BPM electronics with a dedicated RF front end,and a digital BPM,are completed.The cavity design,cold test,system architecture,and first beam test are performed at the Shanghai deep ultraviolet free-electron laser (Zhao et al.in Nucl Instrum Meth A 528(1-2):591-594,2004.doi:10.1016/j.nima.2004.04.108) facility.Results of the beam experiment show that the performance of the CBPM is consistent with basic expectations,and the beam position resolution can fulfill the requirements for the SXFEL project if the beam conditions are optimized.     

An integrative approach to assess qualitative and quantitative consumer feedback

The increasing availability of consumer feedback on the web provides a wealth of information that organizations can use for product and service improvement. Many consumer feedback sites allow users to enter both a quantitative rating and a qualitative critique. Previous research has used this information disjunctively. This work proposes an innovative approach that integrates the two types of information to identify words that are related to positive or negative consumer ratings. A case study shows that this approach does raise some issues not identified using existing analytical approaches.

RF front-end for digital beam position monitor signal processor

RF circuit board has a significant impact on performance of the Digital Beam Position Monitor (DBPM) in storage ring of a synchrotron radiation facility.In this paper,a front-end RF board is designed for DBPM,and schematics of the RF board and the test results are given.In view of the inevitable inconsistency in the multi-channel circuit,a calibration circuit is designed to reduce such an influence.The test results show that the calibration method is useful for beam current dependence which is sensitive to channels inconsistency.