Close proximity detection interference with acoustic telemetry: the importance of considering tag power output in low ambient noise environments
Close proximity detection interference with acoustic telemetry: the importance of considering tag power output in low ambient noise environments
复制标题
近距离检测对声学遥测的干扰：在低环境噪声环境中考虑标签功率输出的重要性
作者：
S. Kessel;N. Hussey;D. Webber;S. Gruber;Joy M Young;M. Smale;A. Fisk
背景当采用声学遥测技术研究水生物种时，了解监测系统的功能动态对于有效的研究设计、数据解释和分析至关重要。通常，研究人员关心最大的有效检测范围，因此倾向于使用研究物种可以携带的最大、最强大的标签，而不会产生相当大的能量负担。在低环境噪声环境、低衰减和反射结构的理想声学条件下，可以在距接收器较远的距离处检测到功率较高的标签，但它们也可能会受到“近距离检测干扰”（CPDI）现象的影响。当反射屏障（例如平静的水面和/或坚硬的基底）导致强烈的传输回波干扰传输序列时，就会发生这种情况。因此，靠近接收器的传输无法有效解码和记录。结果 CPDI 根据使用 Vemco 69 kHz 遥测系统在三个对比研究系统中进行的三个检测范围测试的结果进行评估：受庇护的北极海洋海湾、温带淡水湖和暴露的海洋亚热带珊瑚礁线。对于北极海湾，CPDI 在较低功率 V9 标签中不存在（90% 的传输在 55 m 处接收），但在 V13 标签中有记录，并且在最高功率 V16 标签中最为普遍（分别为 18% 和 8% 在 55 m 处接收的传输）。比较研究系统之间的 V16 标签检测曲线，CPDI 在低环境噪声的北极海湾和温带淡水湖中很明显（最高传输比例分别记录在 370 和 207 m），但在高环境噪声的亚热带珊瑚礁线上不存在。功能示例强调了如果不承认或未考虑 CPDI 可能影响不同研究设计的方式。结论 CPDI 在低环境噪声研究系统中表现最为突出，在研究设计期间选择标签类型/功率时应予以考虑。如果不考虑，CPDI 可能会导致声学遥测数据分析过程中的误解。 CPDI 的识别突出了与声学遥测系统功能相关的复杂性，并支持了彻底检测范围测试的建议。
BackgroundWhen employing acoustic telemetry to study aquatic species, understanding the functional dynamics of the monitoring system is essential for effective study design, data interpretation, and analysis. Typically, researchers are concerned with maximum effective detection range and consequently tend to employ the largest most powerful tags the study species can carry without considerable energetic burden. In ideal acoustic conditions of low ambient noise environments, low attenuation, and reflective structure, higher powered tags can be detected at larger distances from the receiver, but they can also be subject to the phenomenon ‘Close Proximity Detection Interference’ (CPDI). This occurs when reflective barriers, such as a calm water surface and/or hard substrate, result in strong transmission echoes that interfere with the transmission sequence. As a result, transmissions in close proximity to the receiver are not effectively decoded and logged.ResultsCPDI was assessed from the results of three detection range tests conducted using the Vemco 69 kHz telemetry system in three contrasting study systems: a sheltered marine Arctic embayment, a temperate freshwater lake, and an exposed marine sub-tropical reef line. For the Arctic embayment, CPDI was absent with the lower power V9 tag (90% of transmissions received at 55 m) but was recorded for the V13 tag and was most prevalent for the highest power V16 tag (18% and 8% of transmissions received at 55 m, respectively). Comparing V16 tag detection profiles between study systems, CPDI was evident in the low ambient noise Arctic embayment and temperate freshwater lake (highest transmission proportions recorded at 370 and 207 m, respectively) but was absent on the high ambient noise sub-tropical reef line. Functional examples highlight the ways in which CPDI can affect different study designs if not acknowledged or accounted for.ConclusionsCPDI was shown to be the most prominent in low ambient noise study systems and should be considered when choosing tag type/power during study design. If unaccounted for, CPDI could lead to misinterpretation during the analysis of acoustic telemetry data. The identification of CPDI highlights the complexities associated with the functionality of acoustic telemetry systems and supports recommendations for thorough detection range testing.