The digital coherent detection technique has been investigated without any frequency-scanning device in the Brillouin optical time domain reflectometry （BOTDR）, where the simplex pulse codes are applied in the sensi...The digital coherent detection technique has been investigated without any frequency-scanning device in the Brillouin optical time domain reflectometry （BOTDR）, where the simplex pulse codes are applied in the sensing system. The time domain signal of every code sequence is collected by the data acquisition card （DAQ）. A shift-averaging technique is applied in the frequency domain for the reason that the local oscillator （LO） in the coherent detection is fix-frequency deviated from the primary source. With the 31-bit simplex code, the signal-to-noise ratio （SNR） has 3.5-dB enhancement with the same single pulse traces, accordant with the theoretical analysis. The frequency fluctuation for simplex codes is 14.01 MHz less than that for a single pulse as to 4-m spatial resolution. The results are believed to be beneficial for the BOTDR performance improvement.展开更多
Digital Communications, in relation to wireless networks, have taken off in recent years due to the expanding need to communicate faster and more efficiently. A popular way to achieve this is by using wireless Multipl...Digital Communications, in relation to wireless networks, have taken off in recent years due to the expanding need to communicate faster and more efficiently. A popular way to achieve this is by using wireless Multiple Input Multiple Output (MIMO) communication systems. MIMO systems utilize Space Time Block Codes (STBC) as one of the leading ways to obtain higher data rates with limited bandwidth and power. With several STBC methods currently available, this paper analyzes simulations using Orthogonal Space Time Block Codes (OSTBC) in Rayleigh fading channels to evaluate the performance of MIMO systems. The selection to use a Rayleigh fading channel as a model for a non-line-of-sight (nLOS) environment is selected to mimic installations where a large number of signal paths and reflections are expected. All simulations are coded, generated and plotted using MATLAB resulting in graphical data representing the bit-error rate (BER) to signal-to-noise ratio (Eb/N<sub>0</sub>) or SNR. Each simulation captures how different configurations of key variables including code rate, diversity and antenna count can impact system performance. Four modulation schemes (BPSK, QPSK, 16-QAM and 64-QAM) are included in each simulation. Conclusive evidence based upon these simulations suggests higher diversity gains were achieved with a greater number of antennas. The most significant factor for increasing system performance was using a lower count of transmit antennas with a higher count of receive antennas.展开更多
针对传统的DSP代码开发周期较长、效率低等缺点,详细介绍了一种快速、高效的DSP代码开发流程。利用MAT-LAB、S imu link、Real-Tim e W orkshop、DSP B locksets工具箱和TI公司的开发工具CCS IDE,在S imu link环境下,用图形化的方式设计...针对传统的DSP代码开发周期较长、效率低等缺点,详细介绍了一种快速、高效的DSP代码开发流程。利用MAT-LAB、S imu link、Real-Tim e W orkshop、DSP B locksets工具箱和TI公司的开发工具CCS IDE,在S imu link环境下,用图形化的方式设计DSP程序,实现代码的自动生成。完成了DSP系统设计到实施的无缝集成,缩短了开发周期。利用该方法所设计的直流力矩电机控制系统已在TMS320F2812开发板上顺利运行。展开更多
Matlab集成的DSP开发模式是基于模型的图形化设计方法,自动生成符合工程实际的代码,打破了传统设计方法逐行手工编写代码的局限性。提出了基于Matlab和Target for TI C2000工具箱机电系统实时控制平台的设计,通过SVPWM波形的代码自动生...Matlab集成的DSP开发模式是基于模型的图形化设计方法,自动生成符合工程实际的代码,打破了传统设计方法逐行手工编写代码的局限性。提出了基于Matlab和Target for TI C2000工具箱机电系统实时控制平台的设计,通过SVPWM波形的代码自动生成实验及其带三相异步电机运行情况,验证了平台设计方案的可行性。对实时控制平台的应用进行举例探讨,Simulink框图可以自动下载到DSP板上进行测试和运行。平台集成环境高效快捷,模型代码自动生成,可以有效缩短开发周期,减少开发风险,增加研发竞争力。展开更多
基金supported by the National High Technology Research and Development Program of China(Grant No.2012AA041203)the National Natural Science Foundation of China(Grant Nos.61377062 and 31201377)+1 种基金the Program of Shanghai Excellent Technical Leaders,China(Grant No.13XD1425400)the Doctorial Fund of Zhengzhou University of Light Industry,China(Grant No.2013BSJJ012)
文摘The digital coherent detection technique has been investigated without any frequency-scanning device in the Brillouin optical time domain reflectometry （BOTDR）, where the simplex pulse codes are applied in the sensing system. The time domain signal of every code sequence is collected by the data acquisition card （DAQ）. A shift-averaging technique is applied in the frequency domain for the reason that the local oscillator （LO） in the coherent detection is fix-frequency deviated from the primary source. With the 31-bit simplex code, the signal-to-noise ratio （SNR） has 3.5-dB enhancement with the same single pulse traces, accordant with the theoretical analysis. The frequency fluctuation for simplex codes is 14.01 MHz less than that for a single pulse as to 4-m spatial resolution. The results are believed to be beneficial for the BOTDR performance improvement.
文摘Digital Communications, in relation to wireless networks, have taken off in recent years due to the expanding need to communicate faster and more efficiently. A popular way to achieve this is by using wireless Multiple Input Multiple Output (MIMO) communication systems. MIMO systems utilize Space Time Block Codes (STBC) as one of the leading ways to obtain higher data rates with limited bandwidth and power. With several STBC methods currently available, this paper analyzes simulations using Orthogonal Space Time Block Codes (OSTBC) in Rayleigh fading channels to evaluate the performance of MIMO systems. The selection to use a Rayleigh fading channel as a model for a non-line-of-sight (nLOS) environment is selected to mimic installations where a large number of signal paths and reflections are expected. All simulations are coded, generated and plotted using MATLAB resulting in graphical data representing the bit-error rate (BER) to signal-to-noise ratio (Eb/N<sub>0</sub>) or SNR. Each simulation captures how different configurations of key variables including code rate, diversity and antenna count can impact system performance. Four modulation schemes (BPSK, QPSK, 16-QAM and 64-QAM) are included in each simulation. Conclusive evidence based upon these simulations suggests higher diversity gains were achieved with a greater number of antennas. The most significant factor for increasing system performance was using a lower count of transmit antennas with a higher count of receive antennas.
文摘针对传统的DSP代码开发周期较长、效率低等缺点,详细介绍了一种快速、高效的DSP代码开发流程。利用MAT-LAB、S imu link、Real-Tim e W orkshop、DSP B locksets工具箱和TI公司的开发工具CCS IDE,在S imu link环境下,用图形化的方式设计DSP程序,实现代码的自动生成。完成了DSP系统设计到实施的无缝集成,缩短了开发周期。利用该方法所设计的直流力矩电机控制系统已在TMS320F2812开发板上顺利运行。
文摘Matlab集成的DSP开发模式是基于模型的图形化设计方法,自动生成符合工程实际的代码,打破了传统设计方法逐行手工编写代码的局限性。提出了基于Matlab和Target for TI C2000工具箱机电系统实时控制平台的设计,通过SVPWM波形的代码自动生成实验及其带三相异步电机运行情况,验证了平台设计方案的可行性。对实时控制平台的应用进行举例探讨,Simulink框图可以自动下载到DSP板上进行测试和运行。平台集成环境高效快捷,模型代码自动生成,可以有效缩短开发周期,减少开发风险,增加研发竞争力。
