Comparing the Accuracy and Precision of Smartphone and Specialist Handheld GNSS Receivers for Use in Ecological Fieldwork

1. Smartphones are handheld computers and multichannel communication devices that carry an array of sensors and can link with specialist external devices. These powerful tools have an established role in biological recording and ecological surveying. The ability to geolocate accurately is frequently essential to ecological fieldwork. This field study aimed to test the performance of a compact/handheld surveyor-grade GNSS receiver, functioning as an external sensor, compared to smartphones’ inbuilt GNSS receivers and a standard-grade external GNSS receiver.
2. We devised a series of survey protocols to test the horizontal accuracy of GNSS receivers in static and dynamic scenarios typical of ecology fieldwork, estimating the horizontal distance of GNSS measurements under ‘open sky’ conditions from a base station geolocated with centimeter accuracy. Protocols were designed to test the capabilities of GNSS receivers; the absolute horizontal accuracy and precision in static surveys and performance in dynamic surveys, walking a transect with frequent changes of direction, or roaming across the survey area, requiring the GNSS to rapidly reestablish a position fix.
3. In all survey protocols, the surveyor-grade GNSS performed significantly better with lower horizontal distance estimates at the 50th centile and more consistent performance at the 95th centile than the other GNSS receivers, giving median distance estimates of 0.5 - 1.1 m. The median horizontal accuracy of inbuilt GNSS receivers in this trial was 0.9 - 3.4 m under ‘open sky’ conditions.
4. The smartphone GNSS receivers that we tested were accurate to within a few meters. Linking the smartphone with a moderately priced compact/handheld external GNSS receiver significantly improved performance.

1. 智能手机是集成多类传感器、可连接专业外置设备的手持计算机与多通道通信设备。这类功能强大的工具已在生物记录与生态调查中得到广泛应用。精准的地理定位能力往往是生态野外调查的核心需求。本野外研究旨在对比测试一款作为外置传感器的紧凑型手持测量级全球导航卫星系统（GNSS）接收机的性能，其对比对象为智能手机内置的GNSS接收机，以及一款标准级外置GNSS接收机。
2. 我们设计了一系列调查规程，用于测试GNSS接收机在生态野外调查典型的静态与动态场景下的水平定位精度，测试方式为在“开阔无遮挡”环境下，以厘米级精度地理定位的基准站为参照，估算GNSS测量结果的水平偏差。本次规程的测试目标涵盖GNSS接收机的多项性能：静态调查中的绝对水平定位精度与定位精度一致性，以及动态调查中的表现——包括沿频繁转向的样线行进，或在调查区域内漫游时，要求GNSS能够快速重新建立定位锁定。
3. 在所有调查规程中，测量级GNSS接收机的表现显著优于其他两类接收机：其第50百分位数对应的水平距离估算值更低，第95百分位数对应的性能一致性更优，距离估算中位数为0.5~1.1米。本次试验中，智能手机内置GNSS接收机在开阔无遮挡环境下的水平定位精度中位数为0.9~3.4米。
4. 本次测试的智能手机内置GNSS接收机定位精度可达数米级别。将智能手机与一款价位适中的紧凑型手持外置GNSS接收机相连，可显著提升其定位性能。