How Much is the Noise Level be Reduced? – Speech Recognition Threshold in Noise Environments Using a Parametric Speaker –
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Ranging
Recently, we have proposed a 3-D sound system using horizontal arrange loudspeakers by combine the effect of HRTF and the amplitude panning method. In that system, loudspeakers are set at the height of subject's ear level and its sweet-spot is limited by the height of loudspeakers. When listener's ear level is different with loudspeakers, it will cause difficulty of sound localization or breakdown of sound localization. However, it is difficult to adjust properly both the height of loudspeakers and subject's ear level every time. In this paper, we aimed to improve the robustness of the 3-D sound system using vertical loudspeakers array. As a result of experiments, we verify that the loudspeaker arrays can improve the robustness of the 3-D sound system.
Robustness
Directional sound
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In order to meet the needs of high speed,high-precision and large-range laser ranging,the analyses of the problems are discussed on both single frequency and multi-frequency laser ranging methods based on phase-shift measurement.Based on characteristics of the needs of ranging speed,precision and ranging range,the laser ranging method with phase-shift measurement is proposed based on the techniques of frequency reduction and high precision time measurement.Moreover,the method of parameters selection on ranging system is established based on the ranging needs in sequential order of the ranging frequency,time-measurement precision and reference signal frequency,and also the experimental ranging system is set up to verify the ranging method under the conditions of many fileds with high speed,highprecision and large-range laser ranging.The experiment is performed and the experimental results show that the system has a ranging range of 500 m,a ranging precision of 1.08 mm and a ranging speed of0.03-0.04 sunder the conditions of a 300 kHz ranging signal of modulation,a 260 kHz reference signal and a time-measurement precision of 50 ps.The experiment verifies the effectiveness of the ranging method and system,which can lay the foundations for the high speed,high-precision and large-range ranging.
Ranging
Dose-ranging study
Accuracy and precision
SIGNAL (programming language)
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Several asynchronous ranging algorithms have been proposed and studied thus far to improve the inaccurate results of location positioning with conventional ranging algorithms. Even though asynchronous ranging algorithms could yield more accurate and stable ranging results than synchronous counterparts, it requires too much time to complete a ranging process. For this reason, we developed two asynchronous ranging algorithms, called SS-TWR-MA [1] and SDS-TWR-MA [2], [3]. In this paper, we compared the performance of 3 asynchronous ranging approaches, such as SDS-TWR, SS-TWR, and our SDS-TWR-MA, in terms of ranging accuracy and total ranging time. We found out that SDS-TWR-MA provides the best combination between ranging accuracy and total ranging time. That is, it takes least time to provide a specific degree of ranging accuracy.
Ranging
Dose-ranging study
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Ranging information from ultra-wideband (UWB) ranging radios can be used to improve estimated navigation accuracy of a ground robot with other on-board sensors. However, all ranging-aided navigation methods demand the locations of ranging nodes to be known, which is not suitable for time-pressed situations, dynamic cluttered environments, or collaborative navigation applications. This paper describes a new ranging-aided navigation approach that does not require the locations of ranging radios. Our approach formulates relative pose constraints using ranging readings. The formulation is based on geometric relationships between each stationary ranging node and two ranging antennas on the moving robot across time. Our experiments show that estimated navigation accuracy of the ground robot is substantially enhanced with ranging information using our approach under a variety of scenarios, when ranging nodes are placed at unknown locations. We analyze and compare our performance with a traditional ranging-aided method, which requires mapping the positions of ranging nodes. We also demonstrate the applicability of our approach for collaborative navigation in large-scale unknown environments, by using ranging information from one mobile robot to improve navigation estimation of the other robot. This application does not require the installation of ranging nodes at fixed locations.
Ranging
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Interspacecraft ranging is crucial for the suppression of laser frequency noise via time-delay interferometry (TDI). So far, the effects of on-board delays and ambiguities on the LISA ranging observables were neglected in LISA modelling and data processing investigations. In reality, on-board delays cause offsets and timestamping delays in the LISA measurements, and pseudo-random noise (PRN) ranging is ambiguous, as it only determines the range up to an integer multiple of the PRN code length. In this article, we identify the four LISA ranging observables: PRN ranging, the sideband beatnotes at the interspacecraft interferometer, TDI ranging, and ground-based observations. We derive their observation equations in the presence of on-board delays, noise, and ambiguities. We then propose a three-stage ranging sensor fusion to combine these observables in order to gain accurate and precise ranging estimates. We propose to calibrate the on-board delays on ground and to compensate the associated offsets and timestamping delays in an initial data treatment (stage 1). We identify the ranging-related routines, which need to run continuously during operation (stage 2), and implement them numerically. Essentially, this involves the reduction of ranging noise, for which we develop a Kalman filter combining the PRN ranging and the sideband beatnotes. We further implement crosschecks for the PRN ranging ambiguities and offsets (stage 3). We show that both ground-based observations and TDI ranging can be used to resolve the PRN ranging ambiguities. Moreover, we apply TDI ranging to estimate the PRN ranging offsets.
Ranging
Dose-ranging study
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A new embedded ranging system in the ISM band is described. The proposed indoor ranging system combines the advantages of both broadband and narrowband signals to achieve high ranging accuracy in the presence of strong multipath reflections to achieve a good link budget and to be compliant with spectral regulations. The system is based on a WLAN transceiver (with embedded ranging specific circuits) and uses the same frequency band for both communication and ranging purposes so that no separate dedicated ranging transceiver is needed. A prototype has been implemented to evaluate the performance of the proposed technique in a realistic environment. Experimental results show ranging accuracies of less than 20 cm.
Ranging
Narrowband
Dose-ranging study
Transceiver
ISM band
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During this decade, Wireless Sensor Networks (WSNs) brought an increasing interest in the industrial and research world. One of their applications is the indoor localization. The ranging, i.e. the distance evaluation mechanism between nodes, is required to determine the position of the nodes. The research work presented in this article aims to use Ultra Wide Band (UWB) radio links to achieve an efficient ranging, based on Time of Flight (ToF) measurement. A good solution consists in integrating ranging traffic into the usual network mes-sages. However, the ToF ranging process is based on information exchanges which are temporally constrained. Once this information is encapsulated into the usual messages, the temporal constraint cannot be honoured, resulting in important ranging errors due to clock drifts. To mitigate these errors, we have introduced an original dynamic correction technique which enables a precision of twenty centimetres allowing the inclusion of ranging traffic in usual traffic
Ranging
Distance measurement
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Pulsed laser ranging has advantages on the long distance and short ranging time. However, in contrast with other ranging method, the ranging accuracy is relatively low. With the continuous development of imaging LIDAR products, the higher ranging accuracy is required. In order to meet the requirements of high precision pulsed laser ranging, this paper utilizes mathematical simulation software to modeling of waveform generated by different ranging environments, then takes the corresponding method to measure the distance, finally analyses and sums up for the experimental results.
Ranging
Distance measurement
Dose-ranging study
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In this study, the performance of ranging techniques for the Korea Pathfinder Lunar Orbiter (KPLO) space communication system is investigated. KPLO is the first lunar mission of Korea, and pseudo-noise (PN) ranging will be used to support the mission along with sequential ranging. We compared the performance of both ranging techniques using the criteria of accuracy, acquisition probability, and measurement time. First, we investigated the end-to-end accuracy error of a ranging technique incorporating all sources of errors such as from ground stations and the spacecraft communication system. This study demonstrates that increasing the clock frequency of the ranging system is not required when the dominant factor of accuracy error is independent of the thermal noise of the ranging technique being used in the system. Based on the understanding of ranging accuracy, the measurement time of PN and sequential ranging are further investigated and compared, while both techniques satisfied the accuracy and acquisition requirements. We demonstrated that PN ranging performed better than sequential ranging in the signal-to-noise ratio (SNR) regime where KPLO will be operating, and we found that the T2B (weighted-voting balanced Tausworthe, voting v = 2) code is the best choice among the PN codes available for the KPLO mission.
Ranging
Dose-ranging study
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Positioning is useful in a number of applications, for instance smart home, smart factory and health care applications. Time-based ranging methods for positioning are the state-of- the-art but require precise timestamping. Sophisticated ranging methods compensate sources of errors, for instance clock drift caused by a crystal or an asymmetrical measuring principle, to provide precise timestamping. So far, no comprehensive study of different time-based ranging methods using the same hardware and the same evaluation setup was carried out. Consequently, we discuss, implement and evaluate five time-based ranging methods, including Two-Way Ranging, Double Two-Way Ranging, Asymmetrical Double-Sided Two-Way Ranging, Symmetrical DoubleSided Two-Way Ranging and Burst Mode Symmetric DoubleSided Two-Way Ranging. We evaluate accuracy, precision, robustness and run time for the ranging methods and answer the question if the choice of the time-based ranging method matters.
Ranging
Dose-ranging study
Robustness
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