The Development of Loran-C navigation and timing

Hefley, G.

doi:10.6028/nbs.mono.129

Cited by 16 publications

(8 citation statements)

References 8 publications

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“…WHJ'N was not intended to be a pulse system, but a frequency modulated system in which the spectrum was shaped. But it was found to be equivalent to a pulse system as far as separating the ground wave from the skywave was concerned and was found to be unreliable due to unstable sidebands (Hefley, 1972). LF Loran was a practical system but lacked precision because it did not use synchronous detection of the cycle.…”

Section: Spectrummentioning

confidence: 99%

“…frequencies is a type of ground wave propagation. Except for day to night height changes in the ionosphere, these waves become quite stable at great distances (Hefley, 1972).…”

Section: Meeting a Requirement For Precision Navigationmentioning

confidence: 99%

“…of Transportation, 1972) with time. Hefley (1972) in his book on "The Development of Loran-C Navigation and Timing" illustrates a requirement as follows: "on a night flight from Hamlin, Saskatchewan to Gimli, Manitoba in winter, we encountered bad weather. Everything was normal until we realized we were lost.…”

Section: Introductionmentioning

confidence: 99%

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The Impact of the Choice of Frequency and Modulation on Radio Navigation Systems

Johler¹

1974

Navigation

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the choice of frequency for 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 requirement.

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Section: Spectrummentioning

confidence: 99%

“…frequencies is a type of ground wave propagation. Except for day to night height changes in the ionosphere, these waves become quite stable at great distances (Hefley, 1972).…”

Section: Meeting a Requirement For Precision Navigationmentioning

confidence: 99%

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The Impact of the Choice of Frequency and Modulation on Radio Navigation Systems

Johler¹

1974

Navigation

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“…9. The predominant factor &ecting Loran-C groundwave is the variation in velocity of propagation due to surface conductivity (23). The difference in time of arrival at the end of a loo0 mile journey over land as compared with the same distance travelled over sea can amount to l-3 pseconds or 5OQ-1500 feet along the base line.…”

Section: Futurementioning

confidence: 99%

Radio Navigation in North America … the next 25 Years

Beukers

1975

Navigation

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ON MAY16~~ OF THIS YEAR the Secretary. of the Department of Transportation authorized the announcement of the selection of Loran-C as the radio navigation system to serve the coastal confluence region. He also instructed that the titional plan for navigation be amended to reflect this decision, thereby ending a long period of uncertainty in U. S. policy relating .to radio navigational aids. The decision will permit firm plans to be made by both users and manufacturers to derive the best cost benefits from the various radio navigation systems now sponsored by the federal government. This paper explores the impact of the decisions to provide for the co-existence of Loran-C and Omega hyperbolic systems with an orderly phase-out of the Loran-A network. The paper also discusses the current VORTAC and VLF/LF beacon systems in relation to the availability of hyperbolic systems having extensive coverage. A comparison of costs and accuracy of the various systems is provided. A bibliography of reference material is included.

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“…We make the observation from our Loran-C studies that the first prerequisite to a capability for prediction of propagation phenomena is the ability to separate, identify, and under-Introduction Loran-C is a high accuracy, long range puked ground wave radio navigation system [l]. It has also been employed for precision time dissemination [2]. Thus, the relationship between time and geographical position has been emphasized in the development of Loran-C. During the cotiict in South East Asia, it was recognized that Loran-C was the only existent navigational system with the accuracy and repeatability necessary for weapons delivery.…”

mentioning

confidence: 99%