摘要:

ABSTRACTGPS as provided by DOD will give civil aviation users around the world an accurate navigation system that can be used for all phases of flight except precision approach. For densely traveled airspace such as the National Airspace System (NAS) in the United States, GPS by itself does not provide the required availability to serve as the primary‐means navigation system. Therefore, the FAA has designed, developed, and tested a concept called the Wide‐Area Augmentation System (WAAS). GPS augmented by WAAS can provide the integrity, accuracy, and availability required for a primary‐means navigation system for all phases of flight up to Category (CAT) I precision approach in the NAS.This paper provides a summary of the FAA's satellite navigation program, and the strategy and plans for implementing a new satellite navigation system completely different from today's ground‐based systems. It addresses both the operational and technical considerations and requirements involved in implementing WAAS, including the cross‐country flight tests that provided the needed verification to justify a contract award to build and implement an initial WAAS in 1998. The paper also addresses the worldwide expansion of WAAS so that any nation can contribute as little or as much as it wants to a worldwide seam

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1995.tb01900.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTThis paper describes how differential GPS (DGPS) and miniature, low‐cost Integrity Beacon pseudolites were used to carry out 110 successful automatic landings of a United Airlines Boeing 737 aircraft. These autopilot‐in‐the‐loop flight tests using GPS Integrity Beacons (low‐power, ground‐based marker beacon pseudolites placed under the approach path) furnished evidence that GPS can provide the full performance necessary to meet the stringent specifications of Category III. The built‐in geometrical redundancy provided by Integrity Beacon ranging is coupled with centimeter‐level accuracy to provide the system integrity. This integrity—calculated to be better than one part in a billion probability of missed detection—is achieved independently from ground‐based monitors using receiver autonomous integr

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1995.tb01901.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTAn on‐the‐fly (OTF) positioning algorithm is used in a postprocessing mode to determine precisely the vector between two antennas. The algorithm is used in both a standard differential form, between a static and a moving antenna, and a modified relative form, between two moving antennas. The results of two tests that demonstrate this capability are presented. The first test used a turntable with an antenna in motion with respect to a fixed reference site. Independent truth data were obtained by a static survey of the instrument. In the second test, the antennas were mounted on car roofs. The two vehicles performed drive‐by's that were documented by a video camera mounted on one of the cars. The video frames were time‐tagged with GPS, and the distance between vehicles was obtained by measurements of a scale attached to the second vehicle and visible in each video frame at the closest approach. Analysis of the data with fixed and moving reference sites is pr

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1995.tb01902.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTWhen using narrow correlator spacing in a GPS receiver, the C/A‐code tracking errors are on the order of a decimeter. In the presences of multipath signals, tracking errors can be on the order of a few meters. In many differential GPS applications, multipath is the most significant source of error. In a previous paper, the authors demonstrated that it is possible to reduce multipath errors greatly by using the Multipath Estimating Delay Lock Loop (MEDLL). Since then, MEDLL has been implemented into a multichannel receiver that calculates the pseudorange multipath errors in real time.This paper reviews the multipath problem in the GPS receiver and the theory of the MEDLL. Two experiments carried out to evaluate the MEDLL are described. First, measurements were collected simultaneously with the MEDLL receiver and a standard NovAtel narrow‐correlator receiver over a short baseline. Second, the same receivers were connected to a GPS signal simulator so a multipath signal could be introduced in a controlled envirom

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1995.tb01903.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTThis paper describes several receiver autonomous integrity monitoring (RAIM)‐type algorithms that are candidates for use in military Precise Positioning Service (PPS) GPS receivers. Although these PPS RAIM‐type algorithms are based on the Standard Positioning Service (SPS) RAIM and RAIM‐type algorithms described in RTCA/DO‐208, TSO‐C129, and elsewhere, a number of interesting modifications are necessary to adapt those SPS algorithms for use in a PPS receiver. Among these modifications are not having to deal with selective availability (SA) effects and needing to operate in a “fewer‐than‐all‐in‐view” mode.The performance of the PPS RAIM‐type algorithms is presented with respect to both TSO‐C‐129 requirements and global detection availability for en route, terminal, and nonprecision approach operation. The performance of the algorithms is compared against the evolving required navigation performance (RNP) standards for primary‐means navigation, and a prel

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1995.tb01904.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTThe plastic marine sextant has become a common sight in celestial navigation courses owing to its relatively low cost. Mixed statements concerning the quality of such sextants are heard; however, no experimental data seems to have been published concerning their accuracy.The temperature dependence of the index error is proposed as a first approximation indicator of the suitability of plastic sextants for navigation. This paper describes some experiments performed to actually quantify the change in index error with temperature, as well as examine the stability of the instruments' index error at a constant temperature. These results were compared with the results of the same experiment performed on a metal sextant. While the changes in index error with temperature are much larger for the plastic sextants than for the metal sextant used for comparison, the changes were found to be highly linear and repeatable, and the index errors of the plastic sextants, when at a constant temperature, were as stable as the those of the metal sextant under the same conditions.

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1995.tb01905.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY