To obtain high cross-range resolution, the underwater 3-D acoustic imaging system usually requires a rectangular array with a great number of sensors and a large physical size. To reduce the sensor number and the arra...To obtain high cross-range resolution, the underwater 3-D acoustic imaging system usually requires a rectangular array with a great number of sensors and a large physical size. To reduce the sensor number and the array physical size simultaneously, this paper proposes a new underwater 3-D acoustic imaging approach based on a novel multiple-input multiple-output (MIMO) array. Specifically, the MIMO array is composed of four uniform linear arrays (ULAs) located on four sides of a rectangle. The transmitting array composed of two ULAs is located on a pair of opposite sides, and the receiving array composed of another two ULAs is located on the other two sides. Furthermore, narrowband waveforms coded with orthogonal polyphase sequences are employed as transmitting waveforms. When the subcode numbers in the polyphase coded sequences are sufficient, the MIMO array has the same 3-D imaging ability as a rectangular array, which has a two-time bigger size than that of the former. Consequently, the MIMO array can not only save a great number of sensors, but halve the array size, when compared to a rectangular array with the same cross-range resolution. Computer simulations are provided to demonstrate the effectiveness of the proposed imaging approach.展开更多
Underwater acoustic channels pose a great difficulty for the development of high speed communication due to highly limited band-width as well as hostile multipath interference. Enlightened by rapid progress of multipl...Underwater acoustic channels pose a great difficulty for the development of high speed communication due to highly limited band-width as well as hostile multipath interference. Enlightened by rapid progress of multiple-input multiple-output （MIMO） technologies in wireless communication scenarios, MIMO systems offer a potential solution by enabling multiple spatially parallel communication channels to improve communication performance as well as capacity. For MIMO acoustic communications, deep sea channels offer substantial spatial diversity among multiple channels that can be exploited to address simultaneous multipath and co-channel interference. At the same time, there are increasing requirements for high speed underwater communication in very shallow water area （for example, a depth less than 10 m）. In this paper, a space-time multichannel adaptive receiver consisting of multiple decision feedback equalizers （DFE） is adopted as the receiver for a very shallow water MIMO acoustic communication system. The performance of multichannel DFE receivers with relatively small number of receiving elements are analyzed and compared with that of the multichannel time reversal receiver to evaluate the impact of limited spatial diversity on multi-channel equalization and time reversal processing. The results of sea trials in a very shallow water channel are presented to demonstrate the feasibility of very shallow water MIMO acoustic communication.展开更多
针对扬声器阵列指向性声源对驱动电路的需求,设计了一种大功率、高效率以及低失真的8通道数字功放输出级电路。对影响电路实现的关键因素进行了深入分析,通过电路结构以及死区时间的优化设计,降低了总谐波失真、噪声和通道间相位延迟。...针对扬声器阵列指向性声源对驱动电路的需求,设计了一种大功率、高效率以及低失真的8通道数字功放输出级电路。对影响电路实现的关键因素进行了深入分析,通过电路结构以及死区时间的优化设计,降低了总谐波失真、噪声和通道间相位延迟。测试表明,输出功率为1 W时THD+N(Total Harmonic Distortion+Noise,总谐波失真加噪声)达到0.087 5%,20 Hz^22 k Hz频段信噪比达到89.172 d B,通道间相位延迟介于-0.62°^+0.1°之间,单通道效率达到92.1%。展开更多
为解决基于协作的多输入多输出(Multi-input Multi-output,MIMO)同构水下无线传感器网络(Underwater Wireless Sensor Networks,UWSN)的能量节省和能耗均衡的问题,建立了多跳分布式UWSN三维系统模型。文中弥补了DCREDT选择算法能量空间...为解决基于协作的多输入多输出(Multi-input Multi-output,MIMO)同构水下无线传感器网络(Underwater Wireless Sensor Networks,UWSN)的能量节省和能耗均衡的问题,建立了多跳分布式UWSN三维系统模型。文中弥补了DCREDT选择算法能量空间分布不均的不足,通过引入能量门限和距离算法,提出了一种基于能量和距离的带门限水下动态分簇路由算法(Underwater Dynamic Clustering Routing Algorithm Based on Energy and Distance with Thresholds,UDCREDT),同时定量分析了能耗均衡性对网络寿命的影响并确定了门限的取值方法等。通过仿真分析验证了UDCREDT算法的合理性和有效性。相比DCREDT选择算法,所提算法的能耗降低了约6.81%,均衡性提高了约7.98%,有效延长了网络的使用寿命。展开更多
基金supported in part by the Doctorate Foundation of Northwestern Polytechnical University(Grant No. CX201101)
文摘To obtain high cross-range resolution, the underwater 3-D acoustic imaging system usually requires a rectangular array with a great number of sensors and a large physical size. To reduce the sensor number and the array physical size simultaneously, this paper proposes a new underwater 3-D acoustic imaging approach based on a novel multiple-input multiple-output (MIMO) array. Specifically, the MIMO array is composed of four uniform linear arrays (ULAs) located on four sides of a rectangle. The transmitting array composed of two ULAs is located on a pair of opposite sides, and the receiving array composed of another two ULAs is located on the other two sides. Furthermore, narrowband waveforms coded with orthogonal polyphase sequences are employed as transmitting waveforms. When the subcode numbers in the polyphase coded sequences are sufficient, the MIMO array has the same 3-D imaging ability as a rectangular array, which has a two-time bigger size than that of the former. Consequently, the MIMO array can not only save a great number of sensors, but halve the array size, when compared to a rectangular array with the same cross-range resolution. Computer simulations are provided to demonstrate the effectiveness of the proposed imaging approach.
基金Supported by the National Natural Science Foundation of China （Nos. 11274259, 11574258） and the Open Project Program of the Key Laboratory of Underwater Acoustic Signal Processing, the Minister of Educat on （Southeast Un versity） （No. UASP1305）.
文摘Underwater acoustic channels pose a great difficulty for the development of high speed communication due to highly limited band-width as well as hostile multipath interference. Enlightened by rapid progress of multiple-input multiple-output （MIMO） technologies in wireless communication scenarios, MIMO systems offer a potential solution by enabling multiple spatially parallel communication channels to improve communication performance as well as capacity. For MIMO acoustic communications, deep sea channels offer substantial spatial diversity among multiple channels that can be exploited to address simultaneous multipath and co-channel interference. At the same time, there are increasing requirements for high speed underwater communication in very shallow water area （for example, a depth less than 10 m）. In this paper, a space-time multichannel adaptive receiver consisting of multiple decision feedback equalizers （DFE） is adopted as the receiver for a very shallow water MIMO acoustic communication system. The performance of multichannel DFE receivers with relatively small number of receiving elements are analyzed and compared with that of the multichannel time reversal receiver to evaluate the impact of limited spatial diversity on multi-channel equalization and time reversal processing. The results of sea trials in a very shallow water channel are presented to demonstrate the feasibility of very shallow water MIMO acoustic communication.
文摘针对扬声器阵列指向性声源对驱动电路的需求,设计了一种大功率、高效率以及低失真的8通道数字功放输出级电路。对影响电路实现的关键因素进行了深入分析,通过电路结构以及死区时间的优化设计,降低了总谐波失真、噪声和通道间相位延迟。测试表明,输出功率为1 W时THD+N(Total Harmonic Distortion+Noise,总谐波失真加噪声)达到0.087 5%,20 Hz^22 k Hz频段信噪比达到89.172 d B,通道间相位延迟介于-0.62°^+0.1°之间,单通道效率达到92.1%。
文摘为解决基于协作的多输入多输出(Multi-input Multi-output,MIMO)同构水下无线传感器网络(Underwater Wireless Sensor Networks,UWSN)的能量节省和能耗均衡的问题,建立了多跳分布式UWSN三维系统模型。文中弥补了DCREDT选择算法能量空间分布不均的不足,通过引入能量门限和距离算法,提出了一种基于能量和距离的带门限水下动态分簇路由算法(Underwater Dynamic Clustering Routing Algorithm Based on Energy and Distance with Thresholds,UDCREDT),同时定量分析了能耗均衡性对网络寿命的影响并确定了门限的取值方法等。通过仿真分析验证了UDCREDT算法的合理性和有效性。相比DCREDT选择算法,所提算法的能耗降低了约6.81%,均衡性提高了约7.98%,有效延长了网络的使用寿命。
