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
We investigate the XY control and manipulation of the superconducting qubit state using direct digital synthesis(DDS)for the microwave pulse signal generation.The decoherence time, gate fidelity, and other qubit prope...We investigate the XY control and manipulation of the superconducting qubit state using direct digital synthesis(DDS)for the microwave pulse signal generation.The decoherence time, gate fidelity, and other qubit properties are measured and carefully characterized, and compared with the results obtained by using the traditional mixing technique for the microwave pulse generation.In particular, the qubit performance in the state manipulation with respect to the sampling rate of DDS is studied.Our results demonstrate that the present technique provides a simple and effective method for the XY control and manipulation of the superconducting qubit state.Realistic applications of the technique for the possible future scalable superconducting quantum computation are discussed.展开更多
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
Amplitude quantization is one of the main sources of spurious noise frequencies in Direct Digital Frequency Synthesizers (DDFSs), which affect their application to many wireless telecommu- nication systems. In this pa...Amplitude quantization is one of the main sources of spurious noise frequencies in Direct Digital Frequency Synthesizers (DDFSs), which affect their application to many wireless telecommu- nication systems. In this paper, two different kinds of spurious signals due to amplitude quantization in DDFSs are exactly formulated in the time domain and detailedly compared in the frequency do- main, and the effects of the DDFS parameter variations on the spurious performance are thoroughly studied. Then the spectral properties and power levels of the amplitude-quantization spurs in the absence of phase-accumulator truncation are emphatically analyzed by waveform estimation and computer simulation, and several important conclusions are derived which can provide theoretical support for parameter choice and spurious performance evaluation in the application of DDFSs.展开更多
We present a new digital phase lock technology to achieve the frequency control and transformation through high precision multi-cycle group synchronization between signals without the frequency transformation circuit....We present a new digital phase lock technology to achieve the frequency control and transformation through high precision multi-cycle group synchronization between signals without the frequency transformation circuit. In the case of digital sampling, the passing zero point of the phase of the controlled signal has the phase step characteristic, the phase step of the passing zero point is monotonic continuous with high resolution in the phase lock process, and using the border effect of digital fuzzy area, the gate can synchronize with the two signals, the quantization error is reduced. This technique is quite different from the existing methods of frequency transformation and frequency synthesis, the phase change characteristic between the periodic signals with different nominal is used. The phase change has the periodic phenomenon, and it has the high resolution step value. With the application of the physical law, the noise is reduced because of simplifying frequency transformation circuits, and the phase is locked with high precision. The regular phase change between frequency signals is only used for frequency measurement, and the change has evident randomness, but this randomness is greatly reduced in frequency control, and the certainty of the process result is clear. The experiment shows that the short term frequency stability can reach 10-12/s orders of magnitude.展开更多
In the digital synthesis of wideband periodic signals using an Arbitrary Waveform Gen-erator(AWG),the frequency resolution and spectral complexity of the synthesized signals are com-monly limited by the memory capacit...In the digital synthesis of wideband periodic signals using an Arbitrary Waveform Gen-erator(AWG),the frequency resolution and spectral complexity of the synthesized signals are com-monly limited by the memory capacity and clock frequency of the AWG.This paper proposes a novel sequential addressing scheme and then presents several sequences to improve the frequency resolution of the synthesized periodic signals without changing their spectral envelopes and basic time-domain characteristics under the condition of a fixed memory capacity and a fixed clock fre-quency.The main idea of the scheme is using the address generator in an AWG to program and produce addresses to read fixed waveform data in variable order,and thus to generate waveforms of various periods and profiles.The scheme is applied in simulating signal scenarios for military com-munication countermeasure experiments,and achieves high performance.展开更多
Voltage and frequency are usually considered and assessed independently in the design and operation of electrical networks. However, these two are linked. Each and every malfunctioning electrical system has an impact ...Voltage and frequency are usually considered and assessed independently in the design and operation of electrical networks. However, these two are linked. Each and every malfunctioning electrical system has an impact on both voltage and frequency. This paper presents the opportunity for monitoring the distributed electrical energy by means of a system that monitors, controls, and provides a breakpoint based on high or low voltage and frequency tripping mechanism that avoids any damage to the load. The designed system comprised a switch mode power supply (SMPS), a direct digital synthesizer (DDS), and PIC16F876A microcontroller techniques for stable voltage and frequency outputs. Proteus design suite version 8.11 software and Benchcope SDS1102CN were used for modeling and simulation. The hardware prototype was implemented at a telecom cell site for data capturing and analysis. Test results showed that the implementation of the prototype provided stable and constant outputs of 222 V/50 Hz and 112 V/60 Hz which constituted 99% and 99.8% efficiency for voltage and frequency performance respectively. The paper also discusses different technologies that can be adopted by the system to mitigate voltage and frequency effects on customer appliances.展开更多
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.
基金Project was supported by the National Natural Science Foundation of China(Grant No.11890704)the National Key Research and Development Program of China(Grant No.2016YFA0301802)+1 种基金the National Basic Research Program of China(Grant Nos.2015CB921104 and 2016YFA0300601)the Key R&D Program of Guangdong Province,China(Grant No.2018B0303326001)
文摘We investigate the XY control and manipulation of the superconducting qubit state using direct digital synthesis(DDS)for the microwave pulse signal generation.The decoherence time, gate fidelity, and other qubit properties are measured and carefully characterized, and compared with the results obtained by using the traditional mixing technique for the microwave pulse generation.In particular, the qubit performance in the state manipulation with respect to the sampling rate of DDS is studied.Our results demonstrate that the present technique provides a simple and effective method for the XY control and manipulation of the superconducting qubit state.Realistic applications of the technique for the possible future scalable superconducting quantum computation are discussed.
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.
基金Supported by National High-Technology Research and Development Plan of China (Grant No.2006AA01Z452)
文摘Amplitude quantization is one of the main sources of spurious noise frequencies in Direct Digital Frequency Synthesizers (DDFSs), which affect their application to many wireless telecommu- nication systems. In this paper, two different kinds of spurious signals due to amplitude quantization in DDFSs are exactly formulated in the time domain and detailedly compared in the frequency do- main, and the effects of the DDFS parameter variations on the spurious performance are thoroughly studied. Then the spectral properties and power levels of the amplitude-quantization spurs in the absence of phase-accumulator truncation are emphatically analyzed by waveform estimation and computer simulation, and several important conclusions are derived which can provide theoretical support for parameter choice and spurious performance evaluation in the application of DDFSs.
基金Supported by the National Natural Science Foundation of China under Grant No 11173026the International GNSS Monitoring and Assessment System(iGMAS)of National Time Service Centre
文摘We present a new digital phase lock technology to achieve the frequency control and transformation through high precision multi-cycle group synchronization between signals without the frequency transformation circuit. In the case of digital sampling, the passing zero point of the phase of the controlled signal has the phase step characteristic, the phase step of the passing zero point is monotonic continuous with high resolution in the phase lock process, and using the border effect of digital fuzzy area, the gate can synchronize with the two signals, the quantization error is reduced. This technique is quite different from the existing methods of frequency transformation and frequency synthesis, the phase change characteristic between the periodic signals with different nominal is used. The phase change has the periodic phenomenon, and it has the high resolution step value. With the application of the physical law, the noise is reduced because of simplifying frequency transformation circuits, and the phase is locked with high precision. The regular phase change between frequency signals is only used for frequency measurement, and the change has evident randomness, but this randomness is greatly reduced in frequency control, and the certainty of the process result is clear. The experiment shows that the short term frequency stability can reach 10-12/s orders of magnitude.
基金the National Grand Fundamental Research 973 Program of China (No.2004CB318109)the National High-Technology Research and Development Plan of China (No.2006AA01Z452)
文摘In the digital synthesis of wideband periodic signals using an Arbitrary Waveform Gen-erator(AWG),the frequency resolution and spectral complexity of the synthesized signals are com-monly limited by the memory capacity and clock frequency of the AWG.This paper proposes a novel sequential addressing scheme and then presents several sequences to improve the frequency resolution of the synthesized periodic signals without changing their spectral envelopes and basic time-domain characteristics under the condition of a fixed memory capacity and a fixed clock fre-quency.The main idea of the scheme is using the address generator in an AWG to program and produce addresses to read fixed waveform data in variable order,and thus to generate waveforms of various periods and profiles.The scheme is applied in simulating signal scenarios for military com-munication countermeasure experiments,and achieves high performance.
文摘Voltage and frequency are usually considered and assessed independently in the design and operation of electrical networks. However, these two are linked. Each and every malfunctioning electrical system has an impact on both voltage and frequency. This paper presents the opportunity for monitoring the distributed electrical energy by means of a system that monitors, controls, and provides a breakpoint based on high or low voltage and frequency tripping mechanism that avoids any damage to the load. The designed system comprised a switch mode power supply (SMPS), a direct digital synthesizer (DDS), and PIC16F876A microcontroller techniques for stable voltage and frequency outputs. Proteus design suite version 8.11 software and Benchcope SDS1102CN were used for modeling and simulation. The hardware prototype was implemented at a telecom cell site for data capturing and analysis. Test results showed that the implementation of the prototype provided stable and constant outputs of 222 V/50 Hz and 112 V/60 Hz which constituted 99% and 99.8% efficiency for voltage and frequency performance respectively. The paper also discusses different technologies that can be adopted by the system to mitigate voltage and frequency effects on customer appliances.
