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Radio-frequency identification (RFID) transponders are now widely used to track sediment in a variety of environments. A recent innovation placed the transponder inside of a rotating inner mechanism that is designed to minimize missed detections due to burial and shielding or ‘signal collision’ effects between tracers, while also allowing a rapid measurement of the burial depth of the particle. Here we test a developed protocol for burial depth measurement and deploy the ‘Wobblestone’ tracers in the field for the first time. Results show that new tracers can be reliably positioned in the horizontal plane (median error ± 0.03 m) and that the burial depth can be accurately measured (~0.02 m maximum error). The field study was characterized by high mobility and travel lengths, and ~20% of the tracers were buried at depths up to 0.15 m. A comparison of exponential distributions for travel length of surface deposited and buried tracers indicate that the buried tracers on average traveled farther and earlier in the flood event. Tracers that did not move were also buried at one site as a result of sediment transport from upstream. Overall the technique has great potential for characterizing vertical mixing and understanding this rarely considered control on sediment transport. © 2020 John Wiley & Sons, Ltd. 相似文献
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探讨了机载应答设备对GPS—L5接收机的电磁干扰状况。通过机载试验,测量了L5波段电磁频谱,分析测量数据后得到若干能量谱图。并通过与远距离监控装备／塔康导航设备（DME／TACAN）干扰信号的比较得到应答设备比它们具有更小干扰的结论。 相似文献
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Detection ranges and uncertainty of passive Radio Frequency Identification (RFID) transponders for sediment tracking in gravel rivers and coastal environments 
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下载免费PDF全文 Since the earliest use of this technology, a growing number of researchers have employed passive Radio Frequency Identification (RFID) transponders to track sediment transport in gravel rivers and coastal environments. RFID transponders are advantageous because they are inexpensive, durable and use unique codes that allow sediment particle mobility and displacement to be assessed on a clast‐by‐clast basis. Despite these advantages, this technology is in need of a rigorous error and detection analysis. Many studies work with a precision of ~1 m, which is insufficient for some applications, and signal shadowing can occur due to clustering of tagged particles. Information on in‐field performance is also incomplete with respect to burial and submergence, especially for different transponders and antennae combinations. The objectives of this study are to qualify and quantify the factors that influence the detection zone of RFID tracers including antenna type, transponder size, transponder orientation, burial depth, submergence and clustering. Results of this study show that the detection zone is complex in shape due to a set of lobes in the detection field and provide a better understanding of transponder detection shape for different RFID transponder/antenna combinations. This study highlights a strong influence of clustering and submergence, but no significant effect of burial. Finally we propose standard operating procedures for tagging and tracking in rivers and coastal environments. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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The accuracy of GPS/Acoustic positioning is crucial for monitoring seafloor crustal deformation. However, the slant range residual is currently the only indicator used to evaluate the precision of positioning seafloor transponders. This study employs a unique Seafloor Acoustic Transponder System (SATS) to evaluate the accuracy of GPS/Acoustic seafloor positioning. The SATS has three transponders and an attitude sensor in a single unit, which provides true lengths of transponder baselines and true attitude of the SATS to ensure assessment reliability and validity. The proposed approach was tested through a GPS/Acoustic experiment, in which an off-the-shelf acoustic system was used to collect range measurements. Using GPS/Acoustic geodetic observations, the positions of three transponders on the SATS were estimated by an optimization technique combined with ray-tracing calculations. The accuracy of the GPS/Acoustic seafloor positioning is assessed by comparing the true baselines and attitude with the results derived from the position estimates of the three transponders. A sensitivity analysis is conducted to investigate the robustness of the GPS/Acoustic positioning results to changes of sound speed. Experimental results demonstrate that the use of the SATS can help to assess the validity of the GPS and acoustic travel time measurements in the GPS/Acoustic seafloor positioning. 相似文献
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超短基线水声定位系统校准方法研究 总被引：1，自引：0，他引：1
提出了超短基线水声定位系统（USBL）的校准方法，并用模拟数据进行了验证。同商业超短基线定位系统相比，该方法具有精度高、结果可靠、对校准环境要求不高等特点。 相似文献
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