摘要:

ABSTRACTOn September 1, 1909, Dr. Frederick A. Cook telegraphed from Lerwick, in the Shetland Islands, that he had reached the North Pole on April 21, 1908. Six days later Admiral Robert E. Peary telegraphed from Indian Harbor, Labrador, that he had reached the Pole on April 6, 1909. The genial and likable but unscrupulous Cook, by claiming a first, was feted and bemedaled, and he sold articles and books and was paid handsomely for speaking engagements. Peary, because of his vast experience with travel in the arctic, considered it an impossibility for Cook to have travelled to the Pole and back with only two sleds, two eskimo drivers, and 26 dogs. He denounced Cook as a fraud. The millions of people who had hailed Cook as a hero did not like their hero being called a fraud, and many of them denounced Peary and began a campaign of truths, half‐truths, and outright lies to discredit him. Literally millions of words have been written on both sides of the argument. As evidenced by this paper, the argument continue

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1989.tb00987.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACTThis is the second and last installment of the Memoirs of John Alvin Pierce. The first installment (NAVIGATION, Vol. 36, No. 1, Spring 1989) contained a foreword to the Memoirs by Eric Swanson and Mr. Pierce's account of the development of Loran. This installment contains Mr. Pierce's account of the invention and development of Omega. It also includes a question and answer session on the history of Omega, conducted by Robert Revel, the editor of the Memoirs.

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1989.tb00988.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACTThe trend in today's navigation systems is toward Global Positioning System (GPS)/Inertial Navigation System (INS) hybrids. Whether because of GPS outage, or vulnerability, or the fact that GPS does not supply real‐time attitude and heading data, there is a need for a pure, self‐contained INS. In addition, certain operational scenarios require high‐accuracy position, velocity, attitude, and heading data from an INS. Modern INSs are dominated by ring laser gyro (RLG) technology; these systems generally lie in the 1 nmi/h class. To obtain a factor of improvement demands either development of higher‐accuracy (and hence more expensive) inertial sensors, or alternative mechanization of existing inertial sensors.An alternative mechanization ideally suited to today's RLGs is the rate bias technique. This technique solves many of the problems associated with dithered gyros and also attenuates the effects of many of the inertial sensors' errors.This paper addresses the system design, the design rationale, and flight test results demonstrating that a rate bias RLG/INS provides a cost‐effective solution to the pure, high‐accuracy INS

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1989.tb00989.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACTGPS integrity has been studied intensively during the past few years. Two rather distinct approaches to the problem have evolved during this period: (1) Receiver Autonomous Integrity Monitoring (RAIM) and (2) the ground monitoring approach or GPS Integrity Channel (GIC). By and large, these have been considered as competing schemes thus far, but this need not be the case. Quite to the contrary, the two methods are complementary, and they can and should work together to provide the ultimate solution to the GPS integrity problem. The GIC scheme proposed by the GIC Working Group of RTCA Special Committee‐159 will provide the user with integrity information via two geostationary satellites. It is suggested here that the GIC system should be designed such that the user will be able to range on the geostationary satellites, as well as receive integrity information from them. The additional ranging capability will then enhance RAIM and make it possible to have RAIM available 100 percent of the tim

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1989.tb00990.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACTThe generation of differential GPS corrections for general navigation purposes must consider the effects of selective availability, ionosphere, data link latency, and processing time. The U.S. Coast Guard Differential GPS Harbor Entrance program has developed a differential GPS reference station system design that successfully addresses these concerns. This paper presents a high‐level description of this design and some of the test data that led to the critical design decision

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1989.tb00991.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACTThe single‐frequency, C/A‐code GPS user employs a rather simple analytic model of the ionospheric delay of the L1 GPS navigation signal. It is recognized that the model is an approximation and that its use will only partially remove ionospheric effects from the user's navigation solution.To perform an assessment of the residual effects of the ionosphere on navigation accuracy, this paper turns the problem around and uses the ionosphere model in a way that was not originally intended. Let us assume that the model represents truth, and a hypothetical user does not attempt to correct for its effects. With this approach, we have a means for obtaining various statistics of ionospheric effects on a worldwide, 24 h basis. This paper presents results for both horizontal and vertical navigation errors, as well as for time transfer errors. Time transfer results are given both for time transfer that is part of a three‐dimensional navigation solution and for time transfer at a known loc

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1989.tb00992.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACTThe 3‐dimensional position and velocity information provided by GPS makes it particularly interesting for vehicles that do not maintain a constant altitude, such as airplanes and helicopters. Much has been published about aircraft as platforms for GPS receivers. There is a type of “vehicle” for which altitude is the most important dimension—the parachute jumper. Whether in freefall or flying under a parachute canopy, the skydiver is powered by gravity. Position, velocity, and acceleration in the vertical dimension are of vital importance. Altitude lost can never be regained, making it the primary resource to be managed. Until recently, however, GPS receivers have been too bulky, heavy, and power‐hungry to be carried safely by a skydiver.This paper presents the experiences and results of two series of tests in which portable GPS receivers were carried by a freefall parachutist. Position and velocity solutions were recorded during the jumps for later playback and

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1989.tb00993.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1989.tb00994.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY