摘要:

Abstractthe choice of frequencyfor radio navigation is a subject of considerable depth and is inextricably intertwined with requirements for range, accuracy, reliability, cost and impact on competitive services using radiowaves. The basic information for passing judgment on these items comprises the limitations imposed by nature on the system. These limitations are the laws of physics governing the propagation of radio waves.We note in particular that great ranges and hence large coverage areas can be obtained at opposite ends of the spectrum in the OMEGA and SATELLITE systems. We find that great accuracy is accomplished with the ground wave propagation mechanism in the form of Loran–C and Loran–D. We observe that the choice of modulation is critical if high accuracy of position is an objective or requirem

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1974.tb01215.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Abstracttwo current omeganavigation systems designed for airborne use have received military designations: the AN/ARN‐99(V)2 and the AN/ARN‐115. Both use general purpose digital computers to provide fully automatic synchronization, phase tracking, station selection, and diurnal propagation corrections for display of aircraft latitude/longitude position coordinates. Both systems use all three Omega navigational frequencies, but only the ARN‐99(V)2 implements difference frequency lane resolution. The ARN‐115 employs three station hyperbolic geometry to directly determine geographic position. The ARN‐99(V)2 estimates position by statistically optimum weighting of all available Omega measurements in a Kalman filter algorithm. The U. S. Naval Air Test Center recently evaluated both systems during flight tests in P‐3 type aircraft. Observed accuracy of the two mechanizations is presented with emphasis on the effects of station geometry and diurnal propagation correction errors. Experiences with sudden station outages, precipitation static, and on‐board generated coherent interference

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1974.tb01216.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractMany segmentsof the transportation industry will benefit from an automatic vehicle tracking and monitoring system. Such a system automatically reports the position of a number of vehicles (groundborne, seaborne and airborne) to a central location. Dispatchers, such as police, bus or taxi, could more efficiently use their resources if they could track the location of the vehicles they are controlling. Ships on a seaway could be more efficiently scheduled into docks or locks if their position and speed were being tracked. Trucking companies could more effectively protect their cargos from theft or hi‐jacking if they could monitor the location of the trucks.A few automatic vehicle tracking systems have been implemented. As an example the Chicago Metropolitan Bus System has been evaluating a system. The Urban Mass Transportation Administration of the Department of Transportation is conducting a program to determine the best system for “Automatic Vehicle Monitoring”. Tests have been conducted of at least four RF positioning systems to determine which of these technologies meet DOT/UMTA requirements. The next phase will be a trial implementation of one of these tested systems.This paper summarizes the stated user requirements as determined by DOT/UMTA, St. Lawrence Seaway Authority, Forestry Service, Railroads and others. These user requirements include positioning accuracy, number of vehicles to be handled simultaneously, coverage area and implementation and operating costs. A comparison of several technologies is then presented. A very brief description of each system, including Loran–C, Differential Omega, RF trilateration, sign‐post and dead reckoning is presented with a comparison of the advantages and disadvantages in view of the user requirements.A cost comparison is presented which compares the implementation and operating costs of the different systems. Overall efficiency is compared; i.e. cost per user, rf spectrum efficiency, etc.A summary of this comparison concludes that a Loran–C Automatic Tracking System is the most efficient alternative to the requirement for an automatic vehicle positioning system. A description of a Loran–C System then follows, which briefly describes the major system components. Implementation and operating costs are presented. The solution to the two prime problems of a Loran AVM System are described—namely a low‐cost receiver and the availability of relatively low‐cost, small, Loran–C chains pr

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1974.tb01217.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Abstractthis paperdescribes the potential of Loran‐C for providing precision navigation and time service. It also touches on the improvements required in user equipment to exploit this potential.With improved transmitters and improved receivers, taken together, a single fix accuracy can be expected to be less than 14 meters, CEP; the 14 meter value occurring at the outer fringes of the service area (about 1400 kilometers from the farthest transmitter). The improvements required of the transmitters are (1) accurate control of the transmitted wave form, and (2) accurate control of the time of occurrence of the zero crossings of the carrier. Improvements required of the receivers involve (1) more thorough rejection of noise, (2) increase in internal precision, (3) lower probability of false cycle identification, and (4) implementation of the group/phase velocity technique of distance measuring.Loran‐C service can include distribution of epoch time to stationary users with an accuracy of 2 microseconds; and to moving users with an accuracy of 5 microseconds (both 3 standard deviatio

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1974.tb01218.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractLoran‐Dis a highly accuratepulsed hyperbolic navigation system similar to and compatible with Loran‐C, but designed for military tactical use. The helicopter—transportable—transmitter stations have quickly erectable antennas using new tower technology. A signal range over half that of Loran‐C is achieved by the fortunate propagation characteristics of 100 KHz waves, by a modified compatible signal format and by improved transmitter solid state technology. Deployments of the stations in the U.S. and Europe are described. The potential uses of Loran‐D include: gap filler in Loran‐C coverage, a transportable survey system, and long range navigation coverage for many civilian

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1974.tb01219.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractTheNationalMaritimeResearchCenter, Kings Point, N.Y., is conducting projects dealing with the “new technology” in the field of navigation. This paper consists of a survey of this area of activity of the Center. The intent is not only to disseminate information to the wide community of navigators but also to structure a mutually beneficial communications link between the NMRC and the Institute of Navigation. The paper will cover the following projects, some innovative, others extensions of previous programs:—RAPS (Radar Automatic Plotting System)—MASS (MarAd Anti‐Stranding Sonar)—TRANSIM (Simplified Transit)—MARINE RADAR TRANSPONDER—MARSCAN (Maritime Satellites Communication and Navigation System)—INTEGRA

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1974.tb01220.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Abstracta simple graphical methodis presented for determining sextant corrections for dip short of the natural horizon. For the heights of eye and distances normally encountered by small boat sailors when learning navigation, the nomogram yields the customary accuracy (±0′.1) more easily and quickly than the more usual interpolation or calculation metho

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1974.tb01221.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractThe use of relayedOmega for search and rescue (SAR) purposes implies the need for unique, one time position fixes under all weather conditions in real time. Previous Omega applications have not emphasized these requirements. As a result, many of the statistical and engineering measures useful in analyzing the effectiveness of Omega for SAR are unavailable from the existing Omega data base. This paper will address the Navy's effort under both the Global Rescue Alarm Network (GRAN) program and the Air Force's Advanced Survival Avionic Program (ASAP) to define and resolve potential problem areas. The results of an extensive on‐going testing program will be presented.In particular, the following areas will be addressed in detail:• Performance parameters for satellite communication using realistic rescue platforms• Gross resolution of Omega lanes beyond the currently possible 72 nm capability• Characteristics of Omega four frequency transm

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1974.tb01222.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1974.tb01223.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractDifferentialOmegais a navigation system based upon the real‐time dissemination of Omega corrections for an area around a monitor site at a known location. This investigation of its potential for meeting Navy navigational requirements in the U.S. coastal confluence region, where traffic patterns tend to converge, finds that a system of 29 base stations—only one of them new—would provide CCR coverage with cross‐track accuracy of about ¼ nmi. Station spacing proposed for the Gulf of Mexico provides accuracy of ¼ nmi or better throughout the fairway area. Comments on signal format are solicited from all interested parties. The Navy is presently shifting differential Omega work from exploratory development to advanced development and hopes to construct a prototype beginnin

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1974.tb01224.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY