LORAN system

The first LORAN systems were in use before computers were sophisticated enough to perform the complex calculations needed to process the timing comparisons. Early LORAN installations required highly-skilled operators to interpret the radio pulses. A half century later technical innovations eliminated the need for much of the skill once required to use LORAN for navigation. 

A modern Pb/scintillating fiber detector system, incorporating a Loran frequency standard, capable of measuring time intervals with a precision of 20 ps. 

As an illustration of the great locating accuracy achieved by LORAN C systems, commercial fishers sometimes use LORAN C when looking for buoys marking submerged crab traps left unattended in the open ocean. 

A relatively new development in electronically-supported navigation systems, the Global Position Satellite system, seems destined to replace LORAN C. During the years from 1978 through 1995 the United States launched more than two dozen specialized navigational... 

Wind velocity is determined by tracking the balloon by radar or by one of the radio location systems, known as LORAN-C, OMEGA, orVLF. 

Loran. Loran is an acronym for long-range navigation. The system relies on land-based low-frequency radio transmitters. The device calculates a ship s position by the time difference between the receipt of signals from two radio transmitters. The device can display a line of position, which can be plotted on a nautical chart. Most lorans convert the data into longitude and latitude. Since GPS became available, the use of loran has markedly declined. 

Navigation. Navigation encompasses a number of radio applications including radio direction finding (RDF), radar, loran, and Global Positioning System (GPS). 

Loran is an acronym for long-range navigation. The system relies on land-based low-frequency radio transmitters. The device calculates a ship s position by the time difference between the receipt of signals... 

It is useful to think of the sines and cosines in the matrix as the cosines of the angles between the positive direction of the coordinate axes and the directions to the transmitters. This concept can be easily extended to the three-dimensional case in GPS or GLONASS solutions. For a normal GPS-only solution it is usually more convenient to express both satellite and user positions in an Earth centered. Earth fixed (ECEF) coordinate system. In this case the direction cosines are merely the difference of the particular coordinate divided by the range to each satellite. After position solution, an algorithm is used to convert from xyz) to latitude, longitude, and altitude. An alternative that will prove useful for meaningful dilution of precision (DOP) calculations or for integrated GPS/LORAN receivers is to use a East/North/altitude coordinate system and to solve for the azimuth (AZ) and elevation (EL) of the satellites. In this case the direction cosines for each satellite become... 

The structure is ideal for integrated systems where the offset between GPS and GLONASS time may only be known approximately initially, but is known to be virtually constant. This offset would then be estimated as a state variable with some initial uncertainty but with very small Q (fc) driving changes. The same would be true for LORAN/GPS time offsets and the concept could be extended to ASPs for individual stations as well. The ASPs would be represented by very slowly varying states to be estimated. If GPS pseudo-ranges became unavailable such as in an urban canyon, mountain valley, or under heavy foHage cover, the LORAN would now be well calibrated. 

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