Most view articles
2015, 13(2):208-214.
DOI: 10.11805/TKYDA201502.0208
Abstract:
THz atmospheric transmission is an important part of science and technology，which has permeated into almost all applications of terahertz technology. Research on terahertz atmospheric transmission is nearly on horizontal level in the existing literature. A dispersion attenuation model of terahertz atmospheric transmission is presented based on the radiation transfer, dispersion theory and Van-Vleck Weisskopf line-shape combined with Jet Propulsion Laboratory(JPL) database. The absorbing attenuation characteristics of terahertz atmospheric transmission along the slant path between 0.1 THz and 1 THz are studied using this model and compared with the existing literature. The influences of water vapor with different densities on the amplitude, phase and spectrum of the transient terahertz pulse are analyzed. Three relatively stable atmospheric transmission windows in 0.14 THz-0.17 THz，0.19 THz-0.32 THz and 0.32 THz-0.37 THz are obtained. This work has provided a theoretical reference for terahertz time-domain communications and space transmission.
THz atmospheric transmission is an important part of science and technology，which has permeated into almost all applications of terahertz technology. Research on terahertz atmospheric transmission is nearly on horizontal level in the existing literature. A dispersion attenuation model of terahertz atmospheric transmission is presented based on the radiation transfer, dispersion theory and Van-Vleck Weisskopf line-shape combined with Jet Propulsion Laboratory(JPL) database. The absorbing attenuation characteristics of terahertz atmospheric transmission along the slant path between 0.1 THz and 1 THz are studied using this model and compared with the existing literature. The influences of water vapor with different densities on the amplitude, phase and spectrum of the transient terahertz pulse are analyzed. Three relatively stable atmospheric transmission windows in 0.14 THz-0.17 THz，0.19 THz-0.32 THz and 0.32 THz-0.37 THz are obtained. This work has provided a theoretical reference for terahertz time-domain communications and space transmission.
2015, 13(1):1-12.
DOI: 10.11805/TKYDA201501.0001
Abstract:
Terahertz(THz) optoelectronics has promoted the development of the THz generation, transparent control, and detection methods，and hastened many devices in the past decades. Especially, THz metamaterials and metasurfaces will exhibit extraordinary electromagnetic response when the subwavelength scale metal structure is excited by the THz illumination. Therefore, they have been applied to the devices such as wave beam shaper, waveguide, and modulator etc. The THz metamaterials and metasurfaces also show the potential applications in the research fields such as sensors, communications, and radars. In this paper, the works about the spectrum and wavefront modulation with THz metadevices carried out in our group are summarized. The basic theory and corresponding experiment results for different devices are introduced. It is expected these works can pave the avenue of the application of the THz metadevices.
Terahertz(THz) optoelectronics has promoted the development of the THz generation, transparent control, and detection methods，and hastened many devices in the past decades. Especially, THz metamaterials and metasurfaces will exhibit extraordinary electromagnetic response when the subwavelength scale metal structure is excited by the THz illumination. Therefore, they have been applied to the devices such as wave beam shaper, waveguide, and modulator etc. The THz metamaterials and metasurfaces also show the potential applications in the research fields such as sensors, communications, and radars. In this paper, the works about the spectrum and wavefront modulation with THz metadevices carried out in our group are summarized. The basic theory and corresponding experiment results for different devices are introduced. It is expected these works can pave the avenue of the application of the THz metadevices.
2016, 14(4):502-507.
DOI: 10.11805/TKYDA201604.0502
Abstract:
Spintronics is an exciting discipline that involves the study of active control and manipulation of spin degrees of freedom in solid-state systems, the study of spin transport and invention of novel spin-based devices. Some physical phenomena in spintronics, such as exchange magnon, antiferromagnetic resonance, ultrafast spin dynamics, present characteristic frequencies in the THz range. Utilizing the physical principles, the researchers have found and developed several novel THz wave generation methods which give instructions to develop novel THz sources. The methods include: a) THz wave generation based on spin injection; b) THz wave generation based on antiferromagnetic resonance;c) THz wave generation based on ultrafast spin dynamics. THz wave generation methods based on spintronics have great potential which may promote the progress of THz technology.
Spintronics is an exciting discipline that involves the study of active control and manipulation of spin degrees of freedom in solid-state systems, the study of spin transport and invention of novel spin-based devices. Some physical phenomena in spintronics, such as exchange magnon, antiferromagnetic resonance, ultrafast spin dynamics, present characteristic frequencies in the THz range. Utilizing the physical principles, the researchers have found and developed several novel THz wave generation methods which give instructions to develop novel THz sources. The methods include: a) THz wave generation based on spin injection; b) THz wave generation based on antiferromagnetic resonance;c) THz wave generation based on ultrafast spin dynamics. THz wave generation methods based on spintronics have great potential which may promote the progress of THz technology.
2010, 8(2):149-154.
Abstract:
A multiple media system，which was feature-rich and easy to be expanded，was designed and realized. According to the research status and development trend of multiple media system，a scheme，taking OMAP3530 processor as the core of the hardware，was designed based on embedded Linux. The system was composed of multiple media processing module，display module，network module，and Human Computer Interaction(HCI) module. On this basis，the hardware，relative drivers and application layers were designed. The hardware drivers，encoding and decoding algorithms，and software were designed in the environment of Linux 2.6.28 kernel. The experiment results showed that the multiple media system was multi-functional，high-tech-combined，system-integrated and network based. It is an integrated platform with strong scalability and could be functionally reorganized for different users and manufacture. The flexibility and convenience make it a good application prospect in multiple media and communication system.
A multiple media system，which was feature-rich and easy to be expanded，was designed and realized. According to the research status and development trend of multiple media system，a scheme，taking OMAP3530 processor as the core of the hardware，was designed based on embedded Linux. The system was composed of multiple media processing module，display module，network module，and Human Computer Interaction(HCI) module. On this basis，the hardware，relative drivers and application layers were designed. The hardware drivers，encoding and decoding algorithms，and software were designed in the environment of Linux 2.6.28 kernel. The experiment results showed that the multiple media system was multi-functional，high-tech-combined，system-integrated and network based. It is an integrated platform with strong scalability and could be functionally reorganized for different users and manufacture. The flexibility and convenience make it a good application prospect in multiple media and communication system.
2010, 8(2):211-214.
Abstract:
The application of CORDIC(COordinate Rotation DIgital Computing) arithmetic in solving transcendental function has become popular in modern engineering. A brief introduction of CORDIC arithmetic was given in this study. Taking the hyperbolic sine and cosine functions as examples, the method of realizing the arithmetic in FPGA was presented and simulated on ISE(Integrated Software Environment) platform. The result showed this arithmetic was of good precision and instantaneity because of using pipeline. This arithmetic has great practical value in some applications. In addition, a curve of the relationship between the iterative number and the error obtained by the Matlab simulation of the arithmetic can help designers planning the number of iterations for practical applications.
The application of CORDIC(COordinate Rotation DIgital Computing) arithmetic in solving transcendental function has become popular in modern engineering. A brief introduction of CORDIC arithmetic was given in this study. Taking the hyperbolic sine and cosine functions as examples, the method of realizing the arithmetic in FPGA was presented and simulated on ISE(Integrated Software Environment) platform. The result showed this arithmetic was of good precision and instantaneity because of using pipeline. This arithmetic has great practical value in some applications. In addition, a curve of the relationship between the iterative number and the error obtained by the Matlab simulation of the arithmetic can help designers planning the number of iterations for practical applications.
2010, 8(3):247-250.
Abstract:
This article introduces a new type of high speed，multi-modulated digital modulator with adjustable center frequency and bit rate features. It can realize the Quadrature Phase Shift Keying(QPSK) and 16QAM(Quadrature Amplitude Modulation) with 80 MHz center frequency and 7.936 5 MHz bandwidth. The general-purpose modulation arithmetic based on software radio，symbol mapping and the realization of pulse shaping filter are discussed. The measuring results demonstrate that the modulation scheme meets the requirements of practicability and general utilization.
This article introduces a new type of high speed，multi-modulated digital modulator with adjustable center frequency and bit rate features. It can realize the Quadrature Phase Shift Keying(QPSK) and 16QAM(Quadrature Amplitude Modulation) with 80 MHz center frequency and 7.936 5 MHz bandwidth. The general-purpose modulation arithmetic based on software radio，symbol mapping and the realization of pulse shaping filter are discussed. The measuring results demonstrate that the modulation scheme meets the requirements of practicability and general utilization.
2003, 1(1).
Abstract:
Skeleton transform is an important operation in digital image processing. The existing methods for skeleton transform are either complicated or time consumed, so a simple and fast method is presented. It uses a landing and taking-off method to implement 2
Skeleton transform is an important operation in digital image processing. The existing methods for skeleton transform are either complicated or time consumed, so a simple and fast method is presented. It uses a landing and taking-off method to implement 2
2010, 8(1):12-14.
Abstract:
Digital Compass is a kind of device which can acquire the carrier’s attitude. This study introduced the principle of an electronic compass. By using magneto resistive sensor chip HMC1022 made by Honeywell，a 2-axis electronic compass was developed. The amplifier AD623 was used as the signal conditioning circuit. The MPU MSP430 was in charge of A/D converting, azimuth computing and digital outputting. And the Set/Reset(S/R) circuit was adopted so that the error due to null and drift could be minimized. Experiment results showed that the system had good ability to acquire the carrier’s attitude with stable operation and low power consumption. The error was below 1°.
Digital Compass is a kind of device which can acquire the carrier’s attitude. This study introduced the principle of an electronic compass. By using magneto resistive sensor chip HMC1022 made by Honeywell，a 2-axis electronic compass was developed. The amplifier AD623 was used as the signal conditioning circuit. The MPU MSP430 was in charge of A/D converting, azimuth computing and digital outputting. And the Set/Reset(S/R) circuit was adopted so that the error due to null and drift could be minimized. Experiment results showed that the system had good ability to acquire the carrier’s attitude with stable operation and low power consumption. The error was below 1°.
2010, 8(1):1-6.
Abstract:
Active jamming was one of the most important menaces for radars, and the radar detection range was the groundwork for evaluation of anti-jamming. Based on the analysis of theoretical computation and practical anti-jamming measures, a modified mathematical model for calculating the radar detection range in jamming environment was proposed. The simplified model only needed the calculation of a few modification coefficients, so it was convenient for application. The model could also explain the dynamic change of radar detection range under different anti-jamming measures, thus it was helpful for the evaluation and improvement of the anti-jamming performance. The simulations showed validity of the modified model.
Active jamming was one of the most important menaces for radars, and the radar detection range was the groundwork for evaluation of anti-jamming. Based on the analysis of theoretical computation and practical anti-jamming measures, a modified mathematical model for calculating the radar detection range in jamming environment was proposed. The simplified model only needed the calculation of a few modification coefficients, so it was convenient for application. The model could also explain the dynamic change of radar detection range under different anti-jamming measures, thus it was helpful for the evaluation and improvement of the anti-jamming performance. The simulations showed validity of the modified model.
2010, 8(4):451-454.
Abstract:
Radio Frequency IDentification(RFID) series Radio Frequency(RF) card has been applied widely because of its stability，reliability and easy operation features. Aiming at multiple protocols，such as ISO14443 protocol，ISO15693 protocol and Tag-it protocol，this study proposed a new type of circuit design based on Advanced RISC Machine(ARM) for the RFID series RF card reader. The data stream encryption was implemented by using peripheral device in the operation. The system composition，working principle and work flow were introduced. Then，the detailed circuit design of the RF network and encryption hardware were presented，and the test and analysis for the design were performed. The results showed that the circuit could accurately read, write and encrypt various types of card within effective range.
Radio Frequency IDentification(RFID) series Radio Frequency(RF) card has been applied widely because of its stability，reliability and easy operation features. Aiming at multiple protocols，such as ISO14443 protocol，ISO15693 protocol and Tag-it protocol，this study proposed a new type of circuit design based on Advanced RISC Machine(ARM) for the RFID series RF card reader. The data stream encryption was implemented by using peripheral device in the operation. The system composition，working principle and work flow were introduced. Then，the detailed circuit design of the RF network and encryption hardware were presented，and the test and analysis for the design were performed. The results showed that the circuit could accurately read, write and encrypt various types of card within effective range.
2011, 9(1):7-11.
Abstract:
With the development of Internet applications, users’ demand for bandwidth is soaring sharply. Meanwhile，along with the development of broadband access technology, the endpoint can also adopt multiple network accesses. But due to one-way communication of traditional Transmission Control Protocol(TCP)，the waste of resources will exist. To this end，IETF has specifically proposed Multi-Path TCP(MPTCP) to implement TCP multiplexing，thereby enhancing the efficiency and robustness. This paper gives a review of the IETF’s research on MPTCP，including MPTCP architecture, routing and congestion control, aiming to provide a reference for deeply studying.
With the development of Internet applications, users’ demand for bandwidth is soaring sharply. Meanwhile，along with the development of broadband access technology, the endpoint can also adopt multiple network accesses. But due to one-way communication of traditional Transmission Control Protocol(TCP)，the waste of resources will exist. To this end，IETF has specifically proposed Multi-Path TCP(MPTCP) to implement TCP multiplexing，thereby enhancing the efficiency and robustness. This paper gives a review of the IETF’s research on MPTCP，including MPTCP architecture, routing and congestion control, aiming to provide a reference for deeply studying.
2010, 8(3):257-260.
Abstract:
The location estimation in Wireless Sensor Networks(WSN) has been widely discussed in this field recently. This study introduced the location methods that were commonly used in IEEE 802.15.4 network and summarized the main sources of error in Received Signal Strength Indication(RSSI) based location estimation, combined with the approaches to improve location accuracy. The use of the location engine implemented in the CC2431 to estimate location was mainly discussed. The practical measurement results of location were given to prove that the CC2431 had met the application requirements. And all the performance criteria of the location system were analyzed.
The location estimation in Wireless Sensor Networks(WSN) has been widely discussed in this field recently. This study introduced the location methods that were commonly used in IEEE 802.15.4 network and summarized the main sources of error in Received Signal Strength Indication(RSSI) based location estimation, combined with the approaches to improve location accuracy. The use of the location engine implemented in the CC2431 to estimate location was mainly discussed. The practical measurement results of location were given to prove that the CC2431 had met the application requirements. And all the performance criteria of the location system were analyzed.
2012, 10(1):22-26.
Abstract:
Effective choice of the solution is essential to achieve a real-time, bi-directional(full- duplex) communication of the smart grid. The Power Line Carrier(PLC) technology provides a low-cost solution, which suits China's own national conditions. In this paper, the advantages of OFDM PLC modulation technology are introduced. A PLC module of system model is established through the analysis of the input impedance under the low-voltage power line channel. The high-speed PLC module based on low-voltage Power Line is also designed according to the studies of power line channel. The results show that the design of the PLC module has featured high receiving sensitivity and anti-noise ability.
Effective choice of the solution is essential to achieve a real-time, bi-directional(full- duplex) communication of the smart grid. The Power Line Carrier(PLC) technology provides a low-cost solution, which suits China's own national conditions. In this paper, the advantages of OFDM PLC modulation technology are introduced. A PLC module of system model is established through the analysis of the input impedance under the low-voltage power line channel. The high-speed PLC module based on low-voltage Power Line is also designed according to the studies of power line channel. The results show that the design of the PLC module has featured high receiving sensitivity and anti-noise ability.
2010, 8(5):569-572.
Abstract:
Traditional methods and instruments are not able to measure the true Root Mean Square(RMS) of distortion sine wave or non-sine signal accurately. This article introduces a method to measure the true RMS of any high frequency signal by using the true RMS measurement IC，AD536A，designed by AD corporation. The paper analyses the difference between the RMS measured by the average measure method and the true RMS in theory. It explains the disadvantages of current RMS measure method，and presents the design of true RMS measure circuit. The experiment results prove that the proposed method and circuit can measure the true RMS of any high frequency signal accurately.
Traditional methods and instruments are not able to measure the true Root Mean Square(RMS) of distortion sine wave or non-sine signal accurately. This article introduces a method to measure the true RMS of any high frequency signal by using the true RMS measurement IC，AD536A，designed by AD corporation. The paper analyses the difference between the RMS measured by the average measure method and the true RMS in theory. It explains the disadvantages of current RMS measure method，and presents the design of true RMS measure circuit. The experiment results prove that the proposed method and circuit can measure the true RMS of any high frequency signal accurately.
2015, 13(1):31-34.
DOI: 10.11805/TKYDA201501.0031
Abstract:
The background requirements of the fuze antenna in terahertz spectrum as well as its advantages and disadvantages are introduced. The working principles and application characteristics of dielectric lens antenna in terahertz frequency are analyzed in order to implement the terahertz fuze antenna. The longitudinal size of H plane horn antenna can be reduced effectively by using fuze antenna formed by an H plane horn with dielectric lens antenna. The terahertz fuze antenna with different beam angles is achieved by focal technology of lens. The feasibility of the technology solution is verified through simulation.
The background requirements of the fuze antenna in terahertz spectrum as well as its advantages and disadvantages are introduced. The working principles and application characteristics of dielectric lens antenna in terahertz frequency are analyzed in order to implement the terahertz fuze antenna. The longitudinal size of H plane horn antenna can be reduced effectively by using fuze antenna formed by an H plane horn with dielectric lens antenna. The terahertz fuze antenna with different beam angles is achieved by focal technology of lens. The feasibility of the technology solution is verified through simulation.
2010, 8(1):67-70.
Abstract:
The implementation of TCP/IP protocol stack on TM320DM642 platform could provide technological support for the application of multimedia embedded systems to networks. Both the function of TM320DM642 chip and the hierarchical structure of LWIP(Light Weight Internet Protocol) were analyzed. Network communications for TM320DM642 systems were implemented by the transplantation of LWIP, not by a solution scheme of NDK(Network Developer’s Kit). Testing examples verified the effectiveness of the LWIP transplanted method.
The implementation of TCP/IP protocol stack on TM320DM642 platform could provide technological support for the application of multimedia embedded systems to networks. Both the function of TM320DM642 chip and the hierarchical structure of LWIP(Light Weight Internet Protocol) were analyzed. Network communications for TM320DM642 systems were implemented by the transplantation of LWIP, not by a solution scheme of NDK(Network Developer’s Kit). Testing examples verified the effectiveness of the LWIP transplanted method.
2013, 11(4):583-587.
Abstract:
Aiming at the problems in existing underground personnel positioning systems, an assisted positioning method based on pedestrian dead reckoning is proposed. Low-cost Inertial Measurement Unit(IMU) and magnetometer are employed to constitute a stable Attitude Heading Reference System (AHRS). The theory of inertial navigation is utilized, an algorithm for step detection is described, and Zero velocity Update(ZUPT) is adopted for velocity and position estimation to compose a pedestrian dead reckoning system. An experiment is performed in the corridor of a laboratory building to emulate the underground mine road environment. The experimental results demonstrate that the dead reckoning performs well and this method is an effective complement to existing underground positioning by improving the positioning accuracy.
Aiming at the problems in existing underground personnel positioning systems, an assisted positioning method based on pedestrian dead reckoning is proposed. Low-cost Inertial Measurement Unit(IMU) and magnetometer are employed to constitute a stable Attitude Heading Reference System (AHRS). The theory of inertial navigation is utilized, an algorithm for step detection is described, and Zero velocity Update(ZUPT) is adopted for velocity and position estimation to compose a pedestrian dead reckoning system. An experiment is performed in the corridor of a laboratory building to emulate the underground mine road environment. The experimental results demonstrate that the dead reckoning performs well and this method is an effective complement to existing underground positioning by improving the positioning accuracy.
2010, 8(6):647-651.
Abstract:
The design of code tracking loop is a key sector of the realization of noncoherent spectrum spread receiver. In order to realize the code tracking in noncoherent spectrum spread receiver, an energy-normalization digital delay-locked loop was designed, the structure of the loop and the calculating procedure of loop parameters were introduced. The characteristic of noncoherent spectrum spread was analyzed first，and then the key point of the loop design was pointed out. Based on this, the design and realization methods of code loop discriminator, loop filter, early and lag code generator were expatiated. A set of specific loop parameters were introduced as well. Modelsim simulation results and FPGA actual measured data prove the precise code tracking ability of the design.
The design of code tracking loop is a key sector of the realization of noncoherent spectrum spread receiver. In order to realize the code tracking in noncoherent spectrum spread receiver, an energy-normalization digital delay-locked loop was designed, the structure of the loop and the calculating procedure of loop parameters were introduced. The characteristic of noncoherent spectrum spread was analyzed first，and then the key point of the loop design was pointed out. Based on this, the design and realization methods of code loop discriminator, loop filter, early and lag code generator were expatiated. A set of specific loop parameters were introduced as well. Modelsim simulation results and FPGA actual measured data prove the precise code tracking ability of the design.
2015, 13(1):76-79.
DOI: 10.11805/TKYDA201501.0076
Abstract:
Ultra-wideband(UWB) communication shows its advantages of fast data transfer(100 Mb/s or above) in a relatively short distance(typically below 10 m) with relatively weak power consumption (energy spectrum below -41.3 dBm/MHz). Integrated with Multiple Input Multiple Output(MIMO) technology, channel capacity could be further enhanced. As a critical link in the ultrawideband communication，UWB antenna needs extra efforts in design optimization to boost the performance of the whole system. UWB antenna is defined as the antenna whose bandwidth exceeds 500 MHz or relative bandwidth greater than 20%. This paper takes the most representative Vivaldi antenna as a show case for multi-objective optimization design with statistical methods. The optimized miniaturized antenna(sized130 mm×100 mm) shows a -10 dB bandwidth of 2.4 GHz. The design method provides guidance in common wideband，multi-parameter antenna design.
Ultra-wideband(UWB) communication shows its advantages of fast data transfer(100 Mb/s or above) in a relatively short distance(typically below 10 m) with relatively weak power consumption (energy spectrum below -41.3 dBm/MHz). Integrated with Multiple Input Multiple Output(MIMO) technology, channel capacity could be further enhanced. As a critical link in the ultrawideband communication，UWB antenna needs extra efforts in design optimization to boost the performance of the whole system. UWB antenna is defined as the antenna whose bandwidth exceeds 500 MHz or relative bandwidth greater than 20%. This paper takes the most representative Vivaldi antenna as a show case for multi-objective optimization design with statistical methods. The optimized miniaturized antenna(sized130 mm×100 mm) shows a -10 dB bandwidth of 2.4 GHz. The design method provides guidance in common wideband，multi-parameter antenna design.
2010, 8(3):313-317.
Abstract:
High-speed data acquisition system is an important component in modern radar signal processing. A design of high-speed data acquisition system based on band-pass sampling was presented and applied to the signal processing of wideband receiver. The Virtex Series FPGA was used as the main platform to control the high-speed ADC08D1000 for completing data acquisition, transmission，storage and signal processing. High-speed First Input First Output(FIFOs) were selected as the storage devices to implement data rate conversion. The system realized the software and hardware design，and test results verified the feasibility of the solution.
High-speed data acquisition system is an important component in modern radar signal processing. A design of high-speed data acquisition system based on band-pass sampling was presented and applied to the signal processing of wideband receiver. The Virtex Series FPGA was used as the main platform to control the high-speed ADC08D1000 for completing data acquisition, transmission，storage and signal processing. High-speed First Input First Output(FIFOs) were selected as the storage devices to implement data rate conversion. The system realized the software and hardware design，and test results verified the feasibility of the solution.
