Abstract
The utility of the Loran C system by using a manual visual receiver-indicator seems to be increasing now in the world, most of the data on this system, however, are on the coverage area and accuracy by using the full automatic device. We researched and investigated as to the accuracy by manual device at a fixed observation station and it is found that the reading of the time difference often changes at every 10 microseconds in spite of severe measurement and that it will be unavailable to read out without this discrepancy by these conventional receiver-indicators.
