Considering the filter properties of the long horizontal line array （HLA） to the sound field modes, we established an adaptive optimal method to design HLA weights, which can change the filter pass band with the fre...Considering the filter properties of the long horizontal line array （HLA） to the sound field modes, we established an adaptive optimal method to design HLA weights, which can change the filter pass band with the frequency. Using the normal modes theory and combining with the feature of the sound field HLA beamformer, and analyzing the differences of definition and slope in the LOFAR （Low Frequency Analysis Recording） spectrogram between the single-hydrophone and the beamformer, a frequency-adapted optimal-weighted （FAOW） estimate method was obtained by solving a quadratic optimization model with linear equality constraints. The numerical simulation and the experimental data analysis indicated that we can obtain the beamformer signal with the designed optimal array weight which was made up by the Surface-Reflected Bottom-Reflected modes or Non-Surface-Reflected Bottom-Reflected modes. The slope of striations in the signal spectrogram fitted well with the theoretical analysis.展开更多
Due to the shared nature of the wireless medium, the performance of wireless sensor network is often limited by both internal interference and external interference. The internal interference is that simultaneous traf...Due to the shared nature of the wireless medium, the performance of wireless sensor network is often limited by both internal interference and external interference. The internal interference is that simultaneous traffic activity by neighboring nodes in the same network, while the external interference is from wireless transmissions by other types of devices, such as Wi-Fi and Bluetooth nodes. In this paper, we present two channel hopping algorithms for multichannel, single-radio wireless sensor networks. The first algorithm achieves collision-free transmission environment while do not introduce extra control overhead. The second algorithm, in addition to reducing internal interference effects, reduces the external interference effects from Wi-Fi devices. Simulation results show that both of them significantly improve performance in wireless sensor network.展开更多
The Principles of coherent interference suppression are presented by a three-sensor array. The formulae of extracting expected signals from strong interference are derived. The selection of sensor space is discussed a...The Principles of coherent interference suppression are presented by a three-sensor array. The formulae of extracting expected signals from strong interference are derived. The selection of sensor space is discussed and then relationships between the space and frequency point, at which the signals can be extracted, are given. When expected signals are band- limit, the conditions of the selected sensor space, which should be satisfied, are given. Lastly, Performance of interference suppression is analyzed when the amplitude of interference power spectra of signals Received by three sensors fluctuates, and the expressions of relative error of the extracted signals and processing gain are derived. The theoretical and simulation results show that signals can be extracted from strong background interference without any information about signals and interference expect for the arriving direction of signals, that the space between sensors should be smaller than half wavelength of upper limit freqency when the expected signals are band-limit, and that performance of extracting signals will decline with the increase of fluctuation of interference spectrum amplitude.展开更多
The existence of strong interference is the main constraint factor, which influences the detection performance of a signal extraction system. For a sonar with large array the problem of anti-interferences in all-direc...The existence of strong interference is the main constraint factor, which influences the detection performance of a signal extraction system. For a sonar with large array the problem of anti-interferences in all-direction has not been solved yet because of the requirements of over-long time delay line and the over high input- output rate. A method proposed in this paper can be used in the design of adaptive signal processing system with large array for suppressing the strong interference in all-direction. This is a combined architecture of adaptive noise canceller (ANC)and a programmable DICANNE system.When the incident angle between signal θS and interference θI is small, the ANC system is used. When θs-θI is large, a programmable DICANNE system, with rising sampling rate, is used, so that an all-directional anti-interferences system can be obtained. The structure described in this paper is easy to implement in hardware by using DSP chips.The design diagram and implementable method in hardware is presented.展开更多
基金supported by the Program for New Century Excellent Talents in University
文摘Considering the filter properties of the long horizontal line array （HLA） to the sound field modes, we established an adaptive optimal method to design HLA weights, which can change the filter pass band with the frequency. Using the normal modes theory and combining with the feature of the sound field HLA beamformer, and analyzing the differences of definition and slope in the LOFAR （Low Frequency Analysis Recording） spectrogram between the single-hydrophone and the beamformer, a frequency-adapted optimal-weighted （FAOW） estimate method was obtained by solving a quadratic optimization model with linear equality constraints. The numerical simulation and the experimental data analysis indicated that we can obtain the beamformer signal with the designed optimal array weight which was made up by the Surface-Reflected Bottom-Reflected modes or Non-Surface-Reflected Bottom-Reflected modes. The slope of striations in the signal spectrogram fitted well with the theoretical analysis.
基金supported by the Natural Science Foundation of China(No.61574035)National Natural Science Foundation of China(No.61550110244)
文摘Due to the shared nature of the wireless medium, the performance of wireless sensor network is often limited by both internal interference and external interference. The internal interference is that simultaneous traffic activity by neighboring nodes in the same network, while the external interference is from wireless transmissions by other types of devices, such as Wi-Fi and Bluetooth nodes. In this paper, we present two channel hopping algorithms for multichannel, single-radio wireless sensor networks. The first algorithm achieves collision-free transmission environment while do not introduce extra control overhead. The second algorithm, in addition to reducing internal interference effects, reduces the external interference effects from Wi-Fi devices. Simulation results show that both of them significantly improve performance in wireless sensor network.
文摘The Principles of coherent interference suppression are presented by a three-sensor array. The formulae of extracting expected signals from strong interference are derived. The selection of sensor space is discussed and then relationships between the space and frequency point, at which the signals can be extracted, are given. When expected signals are band- limit, the conditions of the selected sensor space, which should be satisfied, are given. Lastly, Performance of interference suppression is analyzed when the amplitude of interference power spectra of signals Received by three sensors fluctuates, and the expressions of relative error of the extracted signals and processing gain are derived. The theoretical and simulation results show that signals can be extracted from strong background interference without any information about signals and interference expect for the arriving direction of signals, that the space between sensors should be smaller than half wavelength of upper limit freqency when the expected signals are band-limit, and that performance of extracting signals will decline with the increase of fluctuation of interference spectrum amplitude.
文摘The existence of strong interference is the main constraint factor, which influences the detection performance of a signal extraction system. For a sonar with large array the problem of anti-interferences in all-direction has not been solved yet because of the requirements of over-long time delay line and the over high input- output rate. A method proposed in this paper can be used in the design of adaptive signal processing system with large array for suppressing the strong interference in all-direction. This is a combined architecture of adaptive noise canceller (ANC)and a programmable DICANNE system.When the incident angle between signal θS and interference θI is small, the ANC system is used. When θs-θI is large, a programmable DICANNE system, with rising sampling rate, is used, so that an all-directional anti-interferences system can be obtained. The structure described in this paper is easy to implement in hardware by using DSP chips.The design diagram and implementable method in hardware is presented.
