評估智慧型手機小米 8 擺放姿態對於精密定位效能之影響

隨著全球導航定位系統（Global Navigation Satellite System, GNSS）的發展，精密單點定位（Precise Point Positioning, PPP）及即時動態定位（Real Time Kinematic, RTK）技術已經可以達到公分級的精度。小米8為全球首款雙頻五星系智慧型手機，其所接收的載波相位觀測量過去幾年已被不少學者用來以RTK、PPP的定位效能評估其是否能達成大地型接收機的定位精度，但各研究使用的定位方法以及對於小米8的擺放姿態不盡相同，且目前尚未看到有文獻將小米8擺放姿態納入考量。因此，本實驗欲以手機的擺放姿態做為操縱變因，探討不同的擺放姿態下對智慧型手機小米8在RTK以及PPP定位效能造成的影響。本實驗分別將小米8豎直和平放以一秒收蒐集兩個小時的觀測資料，兩筆資料以RTK及PPP定位方法解算，分別分析其定位效能。除此之外，本實驗亦分析多星系和GPS-only的觀測資料於RTK、PPP時的定位效能，比較二者的差異。實驗成果顯示當使用GPS-only的觀測資料時，當小米8的擺放姿態為豎直時，其定位效能在RTK及PPP方面皆優於平放；當我們使用multi-GNSS觀測資料進行五星系（GPS/Galileo/BDS/GLONASS/QZSS）的RTK及三星系（GPS/Galileo/QZSS）的PPP解算時，其定位效能皆優於僅使用GPS–only的觀測資料；且當小米8的擺放姿態為豎直時，若使用multi-GNSS觀測資料進行五星系RTK解算，則可以達到水平、垂直方向10公分上下的定位精度。

關鍵字

小米8 ；擺放姿態；智慧型手機；精密單點定位；即時動態定位

並列摘要

With the development of Global Navigation Satellite System (GNSS), Precise Point Positioning (PPP) and Real Time Kinematic (RTK) technologies can provide a precise solution to cm-level. Xiaomi Mi 8 is the world's first smartphone that can receive dual-frequency and five- constellation GNSS observation. In the past few years, many scholars have used the observation data of Mi 8 to evaluate whether it can achieve the positioning accuracy of the geodetic receiver based on the positioning performance of RTK and PPP. However, the position methods and the Mi 8 attitudes used by each research are different, and no literature has been seen to take the attitudes of Mi 8 into consideration. Therefore, this study intends to regard attitudes as the independent variable to evaluate the impact of different attitudes on the RTK and PPP positioning performance of Mi 8. In this study, we used Mi 8 with two different attitudes (straight and lay down) to collect two hours data in every second, and these data was calculated by RTK and PPP to analyze its positioning performance. Also, we analyzed multi-GNSS and GPS-only positioning performance in RTK and PPP, to compare their difference. The research results show that when using GPS-only observation data, when the Xiaomi Mi 8 placed 90°, its positioning performance is better than 0° both in RTK and PPP. When we use five-constellation (GPS/Galileo/BDS/GLONASS/QZSS) observation data for RTK and three-constellation (GPS/Galileo/QZSS) observation data for PPP, both positioning performance is better than GPS-only observation data. When we keep Mi 8 straight, and using multi- constellation observation data for RTK, the horizontal and vertical accuracy can achieved 8.2 cm and 13.8 cm.