摘要:

ABSTRACTon may16, 1974the secretaryof the Department of Transportation announced the selection of Loran–C as the radio navigation system to serve the coastal confluence zone (CCZ). This paper addresses the implementation of Loran–C in the CCZ. Topics covered include proposed station location, coverage, turn‐on schedule (where appropriate) and operational dates for each new chain. Detailed information will be presented concerning the West Coast, Western Canada, and Gulf of Alaska chains which are scheduled to be certified operational January 1, 1977. This latter information will include the construction schedule, characteristics of the electronics equipment and power plants, plus individual station turn‐on and chain calibration sc

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1976.tb00738.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

ABSTRACTThe availability of accurate charts is a necessary part of a complete and useful navigation system. Realizing this, the Coast Guard has exerted a major effort to ensure that navigation charts with Loran–C lines overprinted on them are available for distribution as soon as possible for areas covered by existing Loran‐C chains and throughout the remainder of the Coastal Confluence Zone as Loran–C coverage becomes available. The accurate charting of Loran–C lines–of–position is more difficult than one would think and this paper discusses some of these difficulties encountered. It will also describe the method currently being used to introduce additional secondary phase (ASF) corrections into the charting process to improve the accuracy of the lines. Printing schedules, both present and tentatively planned for the future, will

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1976.tb00739.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

ABSTRACTloran propagation is uniquelypredictable using the integral form of Maxwell's Equations. The demonstrated high—precision repeatability of Loran time differences (TDs) has provided a mechanism with sufficient resolution to detect the extremely small phase variations caused by propagation anomalies. These small variations, denoted by grid warp, can be predicted using surface parameters as input to a computer program based on the theory. This computerized analysis provides a potentially greater accuracy than the conventional measurement process. Further, the computerized technique can be verified with carefully obtained measurements. Thus, a completely unrestricted, three‐dimensional, precision calibration is possible and economically attract

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1976.tb00740.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

ABSTRACTthere are presently at least1350loran–ausers in Oregon representing such major categories as commercial fishermen, recreational boaters, charterboat operators, and towboaters. All existing Loran–A users, plus many others, are potential Loran–C users. The West Coast Loran–C chain is scheduled to start operation on January 1, 1977. Many problems face the prospective Loran–C user in Oregon: receiver cost, charts, lack of information, and misinformation. All of these problems can be alleviated by a longer transition period and a vigorous educatio

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1976.tb00741.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

ABSTRACTuntil the development of a new generationof automatic shipborne receivers, Loran–C was of no importance in the maritime world of Western Europe. This old and very expensive automatic system of high accuracy was only used on board special purpose vessels. Loran–A was employed in those cases where more accurate systems were not available due to their prohibitive prices. So, only the German fishing vessels operating in the North Atlantic are making use of this system to date. The combined Loran–A/C receivers were not very useful because the Loran–C chains in the vicinity of Europe have very long base–lines. Very seldom more than two stations could be picked up with a sufficient S/N ratio.The situation has now thoroughly changed due to the new low–cost automatic receivers which—with regard to their accuracy and sensitivity—more than matched the former automatic equipment, and due to the US plan for phase–out of the Loran–A chains. In Germany, for example, the ocean going fishing vessels have to change their navigation facilities from Loran–A to Loran–C, because their normal working area is the North Atlantic around Iceland and near the North American coast. I believe they will very soon come to appreciate the advantages of Loran–C. I also believe that the German and other merchant fleets of Western Europe sailing to North and Central America will increasingly make use of the Loran–C system, because these areas will be better and more accurately covered with LOPs than ever before, and because the prices for receivers are now reasonable.The aforementioned development has its influences on the work of the German Hydrographic Institute, too. Previously, we made type tests of Loran–A only, but in the future we will also have to type test the automatic Loran–C receivers.We also consider the possible technical and economic advantages of an extension of the planned Loran–C coverage and its connection to the Soviet Loran–C system as a big step towards a standard

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1976.tb00742.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1976.tb00743.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

ABSTRACTSixteen monthshave passed since the 5–7 June 1974 Gettysburg Workshop that was sponsored jointly by the Coast Guard and the Wild Goose Association. Significant action has been taken and progress is being made on the recommendations documented in the Workshop Proceedings.This paper examines the recommendations and discusses progress toward meeting the Workshop challenges as viewed by the author. In particular, progress is discussed concerning future workshops, Coast Guard receiver requirements, the CCZ implementation time table, new Loran–C rate structure, CCZ rate assignments, Loran–C charting, East Coast Loran–C chain reconfiguration, Loran–C system standards, Loran–C User Handbooks, Loran–C R&D efforts, CCZ Loran–C Monitor Plans, midcontinental Loran–C plans and Loran–C for area navigation.Unfortunately, progress has not been made on some important workshop recommendations. These are discussed with respect to what action should be taken and who should accept the challenges.This paper serves as the first documented update report on the Loran–C Workshop. Subsequent update reports are invited to announce and highlight continuing progress toward fulfilling all

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1976.tb00744.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

ABSTRACTAprogram was initiatedby the U.S. Coast Guard during 1973 to develop a Loran–C Replacement Equipment (LRE) package to replace or improve the existing Loran–C ground station equipment. The overall goal of this program is to improve LORSTA operational performance while simultaneously reducing personnel and equipment operating costs. Evaluation of the LRE at 12 LORSTAs during the past two years has shown that the program goal has been achieved. In addition, use of the LRE permits operation of secondary LORSTAs in a semi‐automated mode. This paper describes a joint effort by the Electronics Engineering Division, Coast Guard Headquarters (G–EEE) and Electronics Engineering Center, Wildwood, N.J. (EECEN) engineers to develop, evaluate, and plan for expansion of the LRE program. In addition, the function, operation, and interaction of each individual LRE unit is de

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1976.tb00745.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

ABSTRACTThe assumption underlyingall groundwave radio navigation work, e.g., LORAN, is that each signal travels from transmitter to receiver along a geodesic of the Earth's surface. Therefore, accurate estimation of positions and azimuths along geodesics is an important component of radio navigation. Such computations are normally done under the simplifying assumption that the Earth is an oblate spheroid. In this paper, the theory of geodesies is developed for a general ellipsoid with three unequal axes, using cartesian coordinates instead of the customary latitude and longitude. A first–order solution is obtained for the case where the eccentricity of each of the principal cross–sections of the ellipsoid is small. Numerical results obtained for the special case of an oblate spheroid indicate that the first‐order solution is sufficiently accurate for most applications involving groundwave radio navigation. The extension of the theory to second‐ and higher‐order solutions, if greater accuracy is desired, is straigh

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1976.tb00746.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

ABSTRACTMicroprocessors and their applicationto navigation systems are discussed. A survey of presently available microprocessors is presented, which indicates that only the simplest and slowest devices currently offer any cost advantage over other technologies. A Loran–C receiver using a microprocessor design with a total of 70 integrated circuits is described. A floating point interpreter designed to simplify programming navigational computations on a four bit microprocessor is also described. A coordinate conversion program for Loran using the interpreter has been developed, which uses 4096 words of 8 bit program memory and will compute latitude and longitude to within 50 feet in 22 second

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1976.tb00747.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY