Alfred Leick's research while affiliated with University of Maine and other places

Publications (30)

Chapter
Real-time kinematics (RTK) is a high-precision positioning technique that uses carrier phase and pseudorange measurements in real time. Ultra high frequency (UHF), cellular Global System for Mobile Communications (GSM), Long Term Evolution (LTE), WiFi, or Internet channels can be used for data transmission. The RTK kinematic processing solutions be...
Book
GPS Satellite Surveying is the classic text on the subject, providing the most comprehensive coverage of global navigation satellite systems applications for surveying. Fully updated and expanded to reflect the field's latest developments, this new edition contains new information on GNSS antennas, Precise Point Positioning, Real-time Relative Posi...
Chapter
New global navigation satellite system (GNSS) positioning and timing techniques continues to be developed and refined. This chapter first summarizes undifferenced pseudorange and carrier phase functions between a single station and single satellite. It then addresses operational details such as satellite clock corrections, timing group delay, and i...
Chapter
The first satellite system presented in this chapter is the Global Positioning System (GPS). Next, the chapter reviews the status of the signal transmissions as of the year 2014, including signal structure and navigation message. Then, the Global'naya Navigatsionnaya Sputnikovaya Sistema (GLONASS) system is discussed with emphasis on the broadcast...
Chapter
The objectivity of least-squares quality control is especially useful in surveying when depositing or exchanging observations or verifying the internal accuracy of a survey. This chapter contains compact but complete derivations of least-squares algorithms. First, the statistical nature of measurements is analyzed, followed by a discussion of stoch...
Chapter
The impact of the atmosphere on Global Navigation Satellite System (GNSS) observations is the focus of this chapter. The chapter begins with a general overview of the troposphere and ionosphere as it relates to GPS satellite surveying, and introduces the general form of the index of refraction. It addresses tropospheric refraction starting with the...
Chapter
In many applications of least-squares adjustments the measurements are taken sequentially at discrete epochs in time. Five arrangements are addressed in this chapter: The first case deals with estimation of static parameters. The second refers to the mixed problem of estimating both static and arbitrary varying parameters. The third case introduces...
Chapter
Geodesy is the theoretical and practical framework for utilizing global navigation satellite system (GNSS) vector observations and classical terrestrial observations such as angles and distances. The 3D geodetic model plays a pivotal role in this chapter, followed by the more historical 2D ellipsoidal model, and, last but not least, the popular 3D...
Chapter
Half-Title Page Title Page Copyright Page Table of Contents Preface Acknowledgments Abbreviations
Chapter
This chapter discusses plane and spherical electromagnetic waves of different types of polarization and introduces widely used reference sources of radiation, a Hertzian and a half-wave dipole. It explores antenna directivity and gain. Discussions of antenna phase center, phase center variations, and antenna calibrations are provided. The chapter a...
Article
Processing of GLONASS carrier phase observations differs from that of GPS. These differences are briefly reviewed. Presently GLONASS does not contain selective availability (SA). Simply graphing between-satellite differences reveals parts of SA that is implemented on GPS satellite signals. Intentional degredation of GPS signals was turned off May 1...
Article
Full-text available
The integration of GPS with GLONASS may be considered a major milestone in satellite-based positioning, because it can dramatically improve the reliability and productivity of said positioning. However, unlike GPS, GLONASS satellites transmit signals at different frequencies, which result in significant complexity in terms of modeling and ambiguity...
Article
Double differencing of the carrier phases is a popular technique in global positioning system (GPS) surveying for eliminating receiver and satellite clock errors. However, because each global navigation satellite system (GLONASS) satellite transmits a different carrier frequency, it is not straightforward to constrain double difference integer ambi...
Article
The Orange County GPS survey comprises more than 7,000 vectors linking more than 2,000 stations. The observations were made by private firms and the County of Orange Survey Division staff. Several functions are identified and used to analyze this large network. Weak portions in the network are identified by outliers in these functions. The variance...

Citations

... In this work, a Least Square Adjustments (LSA) is used to compute plane parameters [15]. This method gives the four parameters (i.e. ...
... taciones se configuraron en diferentes tasas de muestreo (sesiones) simultáneamente, las cuales son de 15 segundos, 2 y 50 Hz (Tabla 1), y con un ángulo de elevación de 10° con el objetivo de disminuir los efectos troposféricos en las señales, y tomando en cuenta que los valores habituales para el ángulo de elevación van de 10° a 15° (Seeber, 2003;Leick et al,. 2018;He et al,. 2018), debido a que el efecto multitrayectoria se convierte en el factor dominante cuando el ángulo de elevación del satélite es bajo (Ao et al,. 2015); no obstante, debido a que algunas estaciones presentaron baja velocidad de tranferencia de datos (por el ancho de banda de los dispositivos de red utilizados) se optó por conf ...
... For each baseline, we compute the receiver-to-receiver single differences following the common view approach. Afterwards, the least-squares adjustment has been implemented to estimate the relative clock error between the two receivers after applying the single differences [32], [33]. The estimated parameters vector includes the relative position between the two receivers (∆x, ∆y, ∆z), and the relative clock error (δt). ...
... In Eq. (1), it is possible to observe that when the DoV components are neglected, the error in horizontal geodetic positioning with TS depends on the slope distance and the zenith angle. More details can be found in Leick et al. (2015) and França et al. (2021). Since ΔLED is proportional to the slope distance in Eq. (1), we can express the effect in parts per million (ppm). ...
... Localization using satellites has long been widespread but has attracted renewed interest due to the launching of rising numbers of satellites [1][2][3]. Traditional global navigation satellite systems (GNSS) include the American GPS, the Russian GLONASS (e.g., [4]), the Chinese BeiDou (e.g., [5]) and the European Galileo (e.g., [6]). The current trend in GNSS utilizes multiple GNSS types to improve localization accuracy (e.g., [7]). ...
... However, the DIA method cannot completely ensure the correctness of testing decisions and the unbiases of estimated parameters in practical applications [13]. Moreover, the missed detection, the false alarm, and the incorrect exclusion inevitably occur due to the geometry of the measurement model, the separability among hypotheses, the selected testing statistics, and the predetermined critical values of testing [14]- [16]. ...
... There is a strong interest in including GLONASS satellites in any GPS positioning solution. It is well known that additional satellites strengthen the solution and increase its reliability (Leick 1998). Unlike GPS, GLONASS satellites transmit signals at different frequencies, which causes a significant complexity in terms of the modelling and ambiguity resolution for an integrated GPS and GLONASS data processing system ( Wang et al., 2001). ...