An Application of Photographic Method for the Evaluation Test on Speed Measuring Radiosystem for Ships

Abstract

Since the speed measuring radiosystem can be used for limited visibility, it has been adopted widely by shipyards and many evaluation tests of the radiosystems are applied to our laboratory. The speed data obtained by the radiosystems are usually compared with those obtained by the "Mile Post Method" which may be influenced by human factors. Therefore, the photographic methods are developed for more objective evaluation tests. (1) The differences of speed data by the radiosystem and those obtained from photographs of mile posts and crystal clock were less than 0.1%, which is remarkably small compared with figures of 0.2%〜0.3% by the conventional "Mile Post Method". This suggests that the photographic speed measurements can be applied for general speed measurements when high accuracy is requested. (2) The differences of speed data by the radiosystem and those by the photographs of ship and the crystal clock were less than 0.2% for a ship of 127 meters long. This method is used for the evaluation of the system in a short range.