Characterizing Power Consumption of Dual-Frequency GNSS of a Smartphone

Location service is one of the most widely used features on a smartphone. More and more apps are built based on location services. As such, demand for accurate positioning is ever higher. Mobile brand Xiaomi has introduced Mi 8, the world's first smartphone equipped with a dual-frequency GNSS chipset which is claimed to provide up to decimeter-level positioning accuracy. Such unprecedentedly high location accuracy brought excitement to industry and academia for navigation research and development of emerging apps. On the other hand, there is a significant knowledge gap on the energy efficiency of smartphones equipped with a dual-frequency GNSS chipset. In this paper, we bridge this knowledge gap by performing an empirical study on power consumption of a dual-frequency GNSS phone. To the best our knowledge, this is the first experimental study that characterizes the power consumption of a smartphone equipped with a dual-frequency GNSS chipset and compares the energy efficiency with a single-frequency GNSS phone. We demonstrate that a smartphone with a dual-frequency GNSS chipset consumes 37% more power on average outdoors, and 28% more power indoors, in comparison with a singe-frequency GNSS phone.Comment: Published in IEEE Global Communications Conference (GLOBECOM

Impact of robot antenna calibration on dual-frequency smartphone-based high-accuracy positioning: a case study using the Huawei Mate20X

The access to Android-based Global Navigation Satellite Systems (GNSS) raw measurements has become a strong motivation to investigate the feasibility of smartphone-based positioning. Since the beginning of this research, the smartphone GNSS antenna has been recognized as one of the main limitations. Besides multipath (MP), the radiation pattern of the antenna is the main site-dependent error source of GNSS observations. An absolute antenna calibration has been performed for the dual-frequency Huawei Mate20X. Antenna phase center offset (PCO) and variations (PCV) have been estimated to correct for antenna impact on the L1 and L5 phase observations. Accordingly, we show the relevance of considering the individual PCO and PCV for the two frequencies. The PCV patterns indicate absolute values up to 2 cm and 4 cm for L1 and L5, respectively. The impact of antenna corrections has been assessed in different multipath environments using a high-accuracy positioning algorithm employing an undifferenced observation model and applying ambiguity resolution. Successful ambiguity resolution is shown for a smartphone placed in a low multipath environment on the ground of a soccer field. For a rooftop open-sky test case with large multipath, ambiguity resolution was successful in 19 out of 35 data sets. Overall, the antenna calibration is demonstrated being an asset for smartphone-based positioning with ambiguity resolution, showing cm-level 2D root mean square error (RMSE)

Evaluating the quality of gnss observables and the positional accuracy of the data collected by xioami mi 8 smartphone’s gnss chipset / Avaliando a qualidade dos observáveis gnss e a precisão posicional dos dados coletados pelo chipset gnss do smartphone xioami mi 8

In May 2016, Google LCC announced that GNSS raw data would be available to Android 07 users, thus allowing them to access GNSS observables data, both from carrier cycle count (phase) and pseudo distance measurements. Since then, several studies have tried to analyze the sources of positioning errors obtained with single and dual frequency GNSS chipsets inserted in different smartphone models. In this sense, the main goal of this study is to analyze the quality of GNSS observables and the positional accuracy of the final coordinates, obtained by processing GNSS raw data collected by the Xiaomi Mi 8 and to compare them to those obtained through conventional dual frequency GNSS receivers. Two processing strategies will be used for both datasets, namely: static relative positioning and IBGE Precise Point Positioning. The GNSS data, obtained by both the Xiaomi Mi 8 and the GRS-1 Receiver, manufactured by Topcon, was collected simultaneously, with a tracking time of 3 hours. The raw data was post-processed in RTKlib software in relative mode and in the IBGE PPP online platform. We realized that the signal quality, indicated by the carrier power-to-noise ratio and the carrier wave phase residuals were on average 10 db-Hz lower and 10 times higher for the satellites detected by the Xiaomi Mi 8 compared to the GRS-1 receiver, respectively. While the coordinate accuracy of the Topcon receiver ranged from 1 mm to 6 mm, those of the Xiaomi Mi 8 ranged from 17 cm to 53 cm

GPS carrier phase based precise positioning using characteristics of smartphone antenna

학위논문(석사) -- 서울대학교대학원 : 공과대학 항공우주공학과, 2022.2. 기창돈.현재 대다수의 이용자들은 스마트폰을 바탕으로 GPS 기능을 이용하고 있다. 스마트폰은 다양한 센서와 좋은 성능의 프로세서를 탑재하였음에도 가볍고 간편하게 사용이 가능하기 때문에 기존의 GPS 기능을 이용하던 서비스들을 대체하면서 널리 사용되고 있다. 그러나 스마트폰 자체의 한계로 인하여 현재는 의사거리를 활용한 m급 측위 만이 가능하여서 더 정밀한 서비스를 제공하는 데는 한계가 있다. 그 예로 차량에 탑재된 네비게이션은 차선 간의 구분이 가능하지만, 스마트폰 앱을 이용한 네비게이션 서비스에서는 차선 구분이 불가능하다. 이런 한계에도 불구하고 스마트폰을 이용한 네비게이션은 많은 사용자를 확보하고 있다. 따라서 스마트폰의 GPS 성능이 m급 이하의 deci-meter급 성능으로 개선된다면 현재보다 더 많은 수의 사용자를 확보할 수 있을 것이다. 여기서 cm급의 측위가 가능해진다면 새로운 서비스의 제공도 가능해질 것이라 예상된다. 따라서, 스마트폰에서 반송파 위상 측정치를 이용한 정밀 항법을 수행하고자 하는 시도는 스마트폰이 발매된 이후 지속적으로 시도되었다. 2018년 이후 안드로이드 P가 업데이트 되면서 duty-cycle을 조절할 수 있는 기능이 추가되고 스마트폰 제조사들도 이를 지원하면서 스마트폰에서 반송파 위상 측정치를 이용한 정밀 항법을 수행하는 연구가 활발하게 수행되고 있다. 해당 연구 또한 같은 기조에서 스마트폰에서 cm급 측위를 수행하기 위한 연구를 진행하였다. 스마트폰에서 cm급 측위를 수행하는데 가장 큰 장애물은 스마트폰 안테나로 인한 저품질 반송파 위상 측정치이다. 스마트폰 안테나는 일반적인 GPS 안테나와는 다른 저가의 소형 PIF(Planar Inverted-F) 안테나가 탑재되므로 반송파 위상 측정치를 제대로 수신하는데 어려움이 있다. 따라서 반송파 위상 측정치를 이용한 정밀 항법을 수행하기 위해서는 스마트폰 안테나에 대한 분석이 선행 되어야한다. 본 연구는 스마트폰 안테나의 전방위 특성을 분석하기 위해서 여러 자세에서 측정치를 수집한 후에 신호 세기를 구면 조화 함수를 통해 모델링 하였다. 모델링 결과 스마트폰의 안테나는 불균질한 신호 세기 패턴을 가짐과 동시에 자세에 따라서 신호 세기가 달라지는 것을 확인하였다. 또한 사이클 슬립을 검출한 후에 신호 세기 모델과의 관계를 분석하였다. 또한 스마트폰의 안테나 캘리브레이션을 수행하였다. 기존연구는 스마트폰 안테나 캘리브레이션을 수행하기 위해서 스마트폰을 추가적인 장비와 상용 소프트웨어를 사용했지만 해당 연구에서는 추가적인 장비와 상용 소프트웨어를 사용하지 않고 캘리브레이션을 수행하였다. 캘리브레이션 수행 결과 반송파 위상 측정치 잔여 오차가 64% 감소하였으며 CDGPS 측위 결과 오차가 51% 감소한 3.4cm 정확도로 cm급 측위를 수행하였다.Currently, most users use GPS functions based on smartphones. Smartphones are widely used while replacing services that used to use existing GPS functions because they can be used lightly and easily even though they are equipped with various sensors and good-performance processors. However, due to the limitations of the smartphone itself, only M-level measurements using distance are currently possible, so there is a limit to providing more precise services. For example, navigation mounted on a vehicle can distinguish between lanes, but it is impossible to distinguish lanes in navigation services using smartphone apps. Despite these limitations, navigation using smartphones has many users. Therefore, if the GPS performance of the smartphone is improved to Deci-meter-class performance below meter-class, it will be possible to secure a larger number of users than now. If cm-class positioning becomes possible here, it is expected that new services will be provided. Therefore, attempts to perform precise navigation using carrier phase measurements in smartphones have been continuously attempted since the smartphone was released. With the update of Android P since 2018, the function to control Duty-Cycle has been added, and smartphone manufacturers have also supported it, and research is actively being conducted to perform precise navigation using carrier phase measurements on smartphones. This study was also conducted to perform cm-class positioning on smartphones under the same tone. The biggest obstacle to performing cm-class positioning on a smartphone is a low-quality carrier phase measurement due to a smartphone antenna. Smartphone antennas are equipped with small PIF (Planar Inverted-F) antennas that are different from general GPS antennas, making it difficult to properly receive carrier phase measurements. Therefore, in order to perform a precise navigation using a carrier phase measurement value, analysis of a smartphone antenna must be preceded. In this study, in order to analyze the omnidirectional characteristics of smartphone antennas, measurements were collected from various postures and then signal strength was modeled through a spherical harmonization function. As a result of modeling, it was confirmed that the antenna of the smartphone has a non-uniform signal strength pattern and at the same time, the signal strength varies according to the posture. In addition, after detecting the cycle slip, the relationship with the signal strength model was analyzed. In addition, antenna calibration of the smartphone was performed. Existing studies used additional equipment and commercial software to perform smartphone antenna calibration, but in this study, calibration was performed without using additional equipment and commercial software. As a result of calibration, the residual error of the carrier phase measurement value was reduced by 64%, and as a result of CDGPS measurement, cm-level positioning was performed with 3.4 cm accuracy, which was reduced by 51%.초 록 i 목차 iii 그림 목차 iv 표 목차 vi I. 서론 1 1. 연구의 배경 1 2. 기존 연구 2 3. 연구 내용 10 4. 연구 기여 11 II. 스마트폰 안테나 전방향 특성 분석 12 1. 신호 세기 분석 방법 12 2. 반송파 위상 측정치 분석 방법 15 3. 실측 실험 환경 및 결과 18 III. 스마트폰 안테나 캘리브레이션 29 1. 안테나 캘리브레이션 29 2. 실측 실험 환경 및 결과 33 IV. 스마트폰 정적 CDGPS 37 1. CDGPS 37 2. 실측 실험 환경 및 결과 40 V. 결 론 44 참고 문헌 46 Abstract 49석

Performance Assessment of Kinematic GNSS Positioning with Smartphones Based on Post-Processing of Raw Observations

In recent years, there have been significant technological advances in the development of commonmobile devices. This broughtprogress also in the area of positioning with thesedevices. Allowingaccess to raw GNSS observationsrecorded by mobile devices opened possibilities to apply advanced positioning techniques in order toachieve higher positioning accuracy. The paper describes the results of kinematic measurements of a single-frequency Samsung Galaxy S10+smartphone and a dual-frequency Samsung Galaxy Note10+smartphone. Observations were repeatedly collected at a1.76 km long test route inan urban environment atapedestrian speed. Real-time positioning by autonomous method as well as collection of raw observations into RINEX format and their subsequent post-processing by differential techniques and Precise Point Positioning technique wererealized. The achieved results were compared against a reference linerepresenting the real trajectoryand also againstresults of ageodeticgrade GNSSreceiver.Positioning accuracy of mobile devices ranged from the first decimetres to tens of metres, depending on the environment, tested smartphone and used post-processing technique.Dual-frequency smartphone Samsung Galaxy Note 10+ provided abetter performance compared to the single-frequencydevice. Real-time positioning based on a simple autonomous technique and smoothing algorithm for route optimizationreached lower positioning errors compared to all solutions based on collecting raw observations and their consequent post-processingwith mentioned techniques

Nrtk, ppp or static, that is the question. Testing different positioning solutions for gnss survey

Worldwide, the determination of the coordinates from a Global Navigation Satellite System (GNSS) survey (in Network Real Time Kinematic, Precise Point Positioning, or static mode) has been analysed in several scientific and technical applications. Many of those have been carried out to compare Precise Point Positioning (PPP), Network Real Time Kinematic (NRTK), and static modes’ solutions, usually, using the latter as the true or the most plausible solution. This approach is not always possible as the static mode solution depends on several parameters (baseline length, acquisition time, ionospheric, and tropospheric models, etc.) that must be considered to evaluate the accuracy of the method. This work aims to show the comparison among the GNSS survey methods mentioned above, using some benchmark points. The tests were carried out by comparing the survey methods in pairs to check their solutions congruence. The NRTK and the static solutions refer to a local GNSS CORS network’s analysis. The NRTK positioning has been obtained with different methods (VRS, FKP, NEA) and the PPP solution has been calculated with two different software (RTKLIB and CSRS-PPP). A statistical approach has been performed to check if the distribution frequencies of the coordinate’s residual belong to the normal distribution, for all pairs analysed. The results show that the hypothesis of a normal distribution is confirmed in most of the pairs and, specifically, the Static vs. NRTK pair seems to achieve the best congruence, while involving the PPP approach, pairs obtained with CSRS software achieve better congruence than those involving RTKLIB software

Дослідження точності визначення координат розташування смартфону для використання в прикладних навігаційних застосунках

Загальний обсяг роботи – 100 сторінок, 24 рисунків, 14 таблиць і 15 посилань. Актуальність проблеми: Поширення використання глобальної системи навігації смартфона у побутових навігаційних застосунках викликає сталу потребу ринку глобальної навігації та застосунків покращувати точність визначення координат динамічно у режимі реального часу. Мета та задачі дослідження: Дослідити методи точності та уточнення визначення координат у смартфоні для використання у навігаційних застосунках та розробити систему, що визначає точність визначення координат. Об’єкт дослідження: Глобальні системи навігації у смартфонах Предмет дослідження: Дослідження точності визначення координат розташування смартфону для використання в прикладних навігаційних застосунках Новизна одержаних результатів: Розробка методу дослідження точності визначення координат розташування смартфону.The total volume of work is 100 pages, 24 figures, 14 tables and 15 references. Relevance of the problem: The spread of the use of the global navigation system of the smartphone in home navigation applications causes a constant need of the global navigation market and applications to improve the accuracy of coordinate determination dynamically in real time. Aim and objectives of the study: To investigate the methods of accuracy and refinement of coordinates in a smartphone for use in navigation applications and to develop a system that determines the accuracy of coordinates. Object of research: Global navigation systems in smartphones Subject of research: Research on the accuracy of determining the coordinates of the location of a smartphone for use in application navigation applications Novelty of the obtained results: Development of a method for studying the accuracy of determining the coordinates of the smartphone

Determining peak altitude on maps, books and cartographic materials : multidisciplinary implications

Mountain peaks and their altitude have been of interest to researchers across disciplines. Measurement methods and techniques have changed and developed over the years, leading to more accurate measurements and, consequently, more accurate determination of peak altitudes. This research transpired due to the frequency of misstatements found in existing sources including books, maps, guidebooks and the Internet. Such inaccuracies have the potential to create controversy, especially among peak‐baggers in pursuit of climbing the highest summits. The Polish Sudetes Mountains were selected for this study; 24 summits in the 14 mesoregions were measured. Measurements were obtained employing the global navigation satellite system (GNSS) and light detection and ranging (LiDAR), both modern and highly precise techniques. Moreover, to determine the accuracy of measurements, several of the summits were measured using a mobile phone as an additional method. We compare GNSS vs. LiDAR and verify the level of confidence of peak heights obtained by automatic methods from LiDAR data alone. The GNSS receiver results showed a discrepancy of approximately 10 m compared with other information sources examined. Findings indicate that the heights of peaks presented in cartographic materials are inaccurate, especially in lesser‐known mountain ranges. Furthermore, among all the mountain ranges examined, the results demonstrated that five of the summits were no longer classed as the highest, potentially impacting tourist percep-tions and subsequent visitation. Overall, due to the topographical relief characteristics and varying vegetation cover of mountains, we argue that the re‐measuring procedure should comprise two steps: (1) develop high‐resolution digital elevation models (DEMs) based on LiDAR; (2) assumed heights should be measured using precise GNSS receivers. Unfortunately, due to the time constraints and the prohibitive costs of GNSS, LiDAR continues to be the most common source of new altitude data

Precise Point Positioning Using Dual-Frequency GNSS Observations on Smartphone

The update of the Android system and the emergence of the dual-frequency GNSS chips enable smartphones to acquire dual-frequency GNSS observations. In this paper, the GPS L1/L5 and Galileo E1/E5a dual-frequency PPP (precise point positioning) algorithm based on RTKLIB and GAMP was applied to analyze the positioning performance of the Xiaomi Mi 8 dual-frequency smartphone in static and kinematic modes. The results showed that in the static mode, the RMS position errors of the dual-frequency smartphone PPP solutions in the E, N, and U directions were 21.8 cm, 4.1 cm, and 11.0 cm, respectively, after convergence to 1 m within 102 min. The PPP of dual-frequency smartphone showed similar accuracy with geodetic receiver in single-frequency mode, while geodetic receiver in dual-frequency mode has higher accuracy. In the kinematic mode, the positioning track of the smartphone dual-frequency data had severe fluctuations, the positioning tracks derived from the smartphone and the geodetic receiver showed approximately difference of 3–5 m

Application of GNSS for Vertical Reference Determination

Vertical datum is a reference system used for specifying the elevation of specific points on or near the Earth. Precise and accurate definition and realization of vertical references are, therefore, crucial to ensure consistency between height measurements. The vertical datums can be divided into two categories: 1) vertical geodetic datums and 2) tidal datums, depending on how they are defined and realized. Leveling is a traditional geodetic surveying technique that has been used to realize a vertical geodetic datum. The North American Vertical Datum of 1988 (NAVD88), the current vertical datum for the contiguous United States and Alaska, was established by adjusting the Canadian-Mexican-United States leveling observations. Although great care of NAVD88, it has been identified that NAVD88 is slightly tilted from a geopotential surface and is biased from a least-squares fit of mean sea level. However, re-leveling the continent is cost-prohibitive and may still yield heights with large errors from a geopotential surface. On the other hand, the tidal datum is determined by tidal measurements observed from a tide gauge that is the one of the conventional water level monitoring facilities. However, some challenges of the tide gauges are identified as it required the direct contact with the water. First, installing and maintaining the tide gauge is limited, especially, in extreme environments. Second, the tide gauge is vulnerable to coastal hazards due to potential measurement errors or equipment destructions. Considering the needs in the field of the vertical datum determination, this research explores several novel approaches and techniques utilizing GNSS: First, the optimal combination of the height information from the leveling, GNSS and a geoid models is computed by applying a novel algorithm, Corrector Surface Model (CSM). This study shows the concept of the virtual surface, which compensate the discrepancy between those height measurements, to the real data. In addition, the theoretical algorithms of the combined adjustment are applied to an empirical case study conducted on the selected study area in Oregon for the validation and evaluation. Second, the capability of GNSS for measuring water levels is introduced to establish the basic vertical reference plane by complementing the inconsistency between tidal and geodetic datums. The suggested algorithms are validated by a case study conducted in Cameron, LA during Hurricane Harvey, in 2017, which results reveal that modernized GNSS with an enhanced spectral analysis enables to accurately measure the water levels with high temporal resolution even during an extreme weather event. In addition, the research examines the feasibility of utilizing GNSS-R for realization of vertical datum in the Arctic. For the vertical datum, the water level changes are conventionally monitored by a tidal gauge. However, installing and maintaining tide gauges in the Arctic is challenging due to the extreme environment. In order to overcome the limitation of the traditional tidal gauge, GNSS-R is utilized as an alternative water level monitoring method in the Arctic, which measures the water levels based on remote sensing technique. Considering that GNSS performance at high latitudes is degraded due to satellite geometry and ionospheric effects on GNSS signals, an advanced GNSS-R algorithm is implemented, which successfully measures the highly accurate and precise water level variation in an environmentally challenging region. Finally, GNSS-R technique is adopted for the post-event analysis by taking an advantage of remote-sensing nature of GNSS-R technique. To detect the extreme change of water level, enhanced GNSS-R data processing methods are applied which includes the utilization of multi-band GNSS signals, determination of optimal processing window, and Kalman filtering for height rate determination. In addition, the impact of coastal hazards on water level retrievals is assessed by introducing the confidence level of retrieval (CLR) that indicates the probability of dominant peak representing the roughness of the water surface. The proposed approach is validated by two tsunami events, induced by 2012 Haida Gwaii earthquake and 2015 Chile earthquake and two storm surge events, induced by 2017 Hurricane Harvey and occurred in Alaska in 2019. The key contribution of this research is the utilization of GNSS for the modernized vertical reference determination by compensating the inconsistency between the geodetic and tidal datums