Annual of Navigation 

About: Annual of Navigation is an academic journal. The journal publishes majorly in the area(s): Global Positioning System & GNSS applications. It has an ISSN identifier of 1640-8632. It is also open access. Over the lifetime, 2161 publications have been published receiving 24055 citations.

Theory and Performance of Narrow Correlator Spacing in a GPS Receiver

Abstract: Historically, conventional GPS receivers have used 1.0 chip early-late correlator spacing in the implementation of delay lock loop s (DLLs), However, there are distinct advantages to narrowing this spacing, especially in C/A-code tracking applications. These advantages are the reduction of tracking errors in the presence of both noise and multipath. The primary disadvantage i s that a wider precorrelation bandwidth is required, coupled with higher sample rates and higher digital signal processing rates. However, with current CMOS technology, this is easily achievable and well worth the price. Noise reduction is achieved with narrower spacing because the noise components of the early and late signals are correlated and ten d to cancel, provided that early and late processing are simultaneous (not dithered). Multipath effects are reduced because the DLL discriminator is less distorted by the delayed multipath signal. This paper presents the derivation of these narrow correlator spacing improvements, verified by simulated and tested performance.

Integer Ambiguity Resolution on Undifferenced GPS Phase Measurements and Its Application to PPP and Satellite Precise Orbit Determination

Abstract: Integer ambiguity fixing is routinely applied to double-differenced GPS phase measurements to achieve precise positioning. Double-differencing is interesting because it removes most of the common errors between the different signal paths. However, if common errors can be estimated it becomes attractive to fix integer ambiguities on undifferenced measurements. Phase measurements then become pseudorange-like measurements with a noise level of a few millimeters. This paper introduces a new method for fixing dual-frequency GPS ambiguities on undifferenced phase measurements either locally or globally. The clocks for the GPS constellation obtained during this process can be used for precise point positioning of ground based receivers and for precise orbit determination of low Earth orbiting satellites. The resulting positioning precision is comparable to that of standard differential positioning without the need for a reference station. Ambiguity-fixed satellite orbits for the GRACE and Jason satellites are more precise than the most precise solution available today.

Binary Offset Carrier Modulations for Radionavigation

Abstract: Current signaling for GPS employs phase shift keying (PSK) modulation using conventional rectangular (non-return to zero) spreading symbols. Attention has been focused primarily on the design of the spreading code and selection of the keying rates. But better modulation designs are available for next-generation radionavigation systems, offering improved performance and the opportunity for spectrum sharing while retaining implementation simplicity. This paper describes a class of particularly attractive modulations called binary offset carrier (BOC). It presents important characteristics of modulations for radionavigation, introduces several specific BOC designs that satisfy different applications in evolving radionavigation systems, describes receiver processing for these modulations, and provides analytical and numerical results that describe the modulations' performance and demonstrate advantages over comparable conventional PSK modulations with rectangular spreading symbols.

Autonomous GPS Integrity Monitoring Using the Pseudorange Residual

Abstract: The use of GPS for navigation-critical applications such as aircraft nonprecision approach or harbor and river crossings requires the navigation data to be both extremely accurate and extremely reliable. This paper describes a method for autonomous GPS satellite failure detection and isolation (D/I). The test statistic for the D/I algorithm is the range residual parameter for six or more satellites in view. Based on experiments conducted at Stanford, nominal carrier-aided pseudorange measurement errors are modeled as Gaussian random variables with mean in the range from - 5 m to + 5 m and standard deviation of 0.4 m. The theoretical statistical distribution of the range residual is given. Monte Carlo simulations present results of applying the algorithm to measurement sets containing a biased measurement. With a 100 m biased measurement present, successful detection is achieved 99.9 percent of the time, and successful D/I is achieved 72.2 percent of the time. The user is always aware when isolation is not possible. User positioning errors resulting from application of the algorithm are always the same or better than with the all-in-view solution.

GPS Signal Structure and Performance Characteristics

Abstract: Details of the gps signal structure are discussed as relates to the signal generation and the performance of the navigation system. GPS performance objectives, orbit geometry, and propagation effects are summarized in order to gain better understanding of the signal and what characteristics it must provide. With these performance objectives as a preface, the details of the signal are described, showing the details of the dual frequency transmission and both the precision P and clear/acquisition C/A codes and their characteristics. Finally, the basic performance of simplified receivers operating on this received signal is discussed. It is shown that an rms position error of less than 10 meters is well within the achievable performance bounds of the system.