Application of Additional Secondary Factors to LORAN-C Positions for Hydrographic Operations
NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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The application of LORAN-C in the hyperbolic mode as a positioning system for hydrographic surveys was investigated. Observed LORAN-C time differences from a field test conducted in Monterey Bay, California were compared to calculated time differences determined from geographic positions based on a microwave positioning system. Four methods were used to determine the calculated time differences. The first three methods were 1 applying only the seawater Secondary Factory, 2 computing the time difference based on a Semi-Empirical TD Grid, and 3applying ASF Correctors from the DMAHTC LORAN-C correction Table. The final method applied multiple observed ASF Correctors at five minute latitude and longitude intervals. By applying multiple observed ASF Correctors, which was the most accurate method, a 38.3 meter 1 drms with a lane offset of 3 to 12 meters using the 9940 X-Y LORAN-C combination was obtained. Based upon the results presented, it may be possible to use LORAN-C for hydrographic surveys at scales of 180,000.
- Physical and Dynamic Oceanography
- Radiofrequency Wave Propagation