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 calib...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.展开更多
A digital biomedical electrical impedance tomography (EIT) system is developed with the aid of FPGA. The key elements of EIT system are described specifically in the paper. The functions are realized to generate excit...A digital biomedical electrical impedance tomography (EIT) system is developed with the aid of FPGA. The key elements of EIT system are described specifically in the paper. The functions are realized to generate excitation source, switch electrode channels, deal collected signals, demodulate measured voltages etc. The system is tested by a circular tank with 16 stainless electrodes attached around the boundary. The adjacent incentive adjacent measurement mode is adapted to collect boundary voltages of the interesting field. By testing, the system works with 36 dB signal-to-noise ratio (SNR) when 1 mA 100 KHz current is applied into a homogenous tank.展开更多
Phase modulation is a crucial step when the frequency-based wavefront optimization technique is exploited to measure the optical transmission matrix(TM) of a scattering medium. We report a simple but powerful method, ...Phase modulation is a crucial step when the frequency-based wavefront optimization technique is exploited to measure the optical transmission matrix(TM) of a scattering medium. We report a simple but powerful method, direct digital frequency synthesis(DDS) technology to modulate the phase front of the laser and measure the TM. By judiciously modulating the phase front of a He–Ne laser beam, we experimentally generate a high quality focus at any targeted location through a 2 mm thick 120 grit ground glass diffuser, which is commercially used in laser display and laser holographic display for improving brightness uniformity and reducing speckle. The signal to noise ratio(SNR) of the clear round focus is 50 and the size is about 44 μm. Our study will open up new avenues for enhancing light energy delivery to the optical engine in laser TV to lower the power consumption, phase compensation to reduce the speckle noise, and controlling the lasing threshold in random lasers.展开更多
Based on the analysis of the spurious introduced by phase accumulation truncation which was made by Nicholas, a new simplified algorithm for spurious spectrum in the presence of phase truncation is presented by using ...Based on the analysis of the spurious introduced by phase accumulation truncation which was made by Nicholas, a new simplified algorithm for spurious spectrum in the presence of phase truncation is presented by using the mapping mathematics and number theoretic method, it is possible to precisely analyze the spurious location and the spurious amplitude introduced by phase truncation in practical applications by computer.展开更多
文章主要介绍一种现场可编程逻辑门阵列(Field Programmable Gate Array,FPGA)控制数字频率合成器(Direct Digital Synthesizer,DDS)实现四进制移频键控(Quaternary Frequency Shift Keying,4FSK)&频率调制(Frequency Modulation,FM...文章主要介绍一种现场可编程逻辑门阵列(Field Programmable Gate Array,FPGA)控制数字频率合成器(Direct Digital Synthesizer,DDS)实现四进制移频键控(Quaternary Frequency Shift Keying,4FSK)&频率调制(Frequency Modulation,FM)调制载波的设计方案,给出技术指标参数、硬件组成框图以及信号处理流程,对4FSK的调制信号和FM信号产生的实施方法进行探讨,并对电路框图中的关键器件进行国产化设计选型。展开更多
基金Supported by the National Natural Science Foundation of China(No.11075198)
文摘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.
文摘A digital biomedical electrical impedance tomography (EIT) system is developed with the aid of FPGA. The key elements of EIT system are described specifically in the paper. The functions are realized to generate excitation source, switch electrode channels, deal collected signals, demodulate measured voltages etc. The system is tested by a circular tank with 16 stainless electrodes attached around the boundary. The adjacent incentive adjacent measurement mode is adapted to collect boundary voltages of the interesting field. By testing, the system works with 36 dB signal-to-noise ratio (SNR) when 1 mA 100 KHz current is applied into a homogenous tank.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2016YFB0401902 and 2016YFB0402001)Key-Area Research and Development Program of Guang Dong Province,China(Grant No.2019B010926001)。
文摘Phase modulation is a crucial step when the frequency-based wavefront optimization technique is exploited to measure the optical transmission matrix(TM) of a scattering medium. We report a simple but powerful method, direct digital frequency synthesis(DDS) technology to modulate the phase front of the laser and measure the TM. By judiciously modulating the phase front of a He–Ne laser beam, we experimentally generate a high quality focus at any targeted location through a 2 mm thick 120 grit ground glass diffuser, which is commercially used in laser display and laser holographic display for improving brightness uniformity and reducing speckle. The signal to noise ratio(SNR) of the clear round focus is 50 and the size is about 44 μm. Our study will open up new avenues for enhancing light energy delivery to the optical engine in laser TV to lower the power consumption, phase compensation to reduce the speckle noise, and controlling the lasing threshold in random lasers.
文摘Based on the analysis of the spurious introduced by phase accumulation truncation which was made by Nicholas, a new simplified algorithm for spurious spectrum in the presence of phase truncation is presented by using the mapping mathematics and number theoretic method, it is possible to precisely analyze the spurious location and the spurious amplitude introduced by phase truncation in practical applications by computer.
文摘文章主要介绍一种现场可编程逻辑门阵列(Field Programmable Gate Array,FPGA)控制数字频率合成器(Direct Digital Synthesizer,DDS)实现四进制移频键控(Quaternary Frequency Shift Keying,4FSK)&频率调制(Frequency Modulation,FM)调制载波的设计方案,给出技术指标参数、硬件组成框图以及信号处理流程,对4FSK的调制信号和FM信号产生的实施方法进行探讨,并对电路框图中的关键器件进行国产化设计选型。
