선박이 항해 중 침로와 속력의 변화가 NNSS 측위정도에 미치는 영향을 분석하기 위해 위성별, 위성통과방향별, 앙각별로 계산기 simulation한 결과는 다음과 같다. 1. 위성의 앙각과 통과방향이 일정한 경우 위성의 종류에 따른 측위정도는 그 차이가 거의 없었다. 2. 속력오차에 의한 측위정도는 선속의 대소에는 관계없이 선속오차의 절대치에 비례하고 선박의 침로에 따라 달라진다. 3. 속력오차가 일정할 경우 위성의 통과방향에 따라 측위정도가 달라지며 동측북상과 서측남하인 경우와 서측북상과 동측남하인 경우는 서로 비슷한 측위정도를 나타내었다. 4. 선박의 침로가 남북방향일 때가 동서방향일 때보다도 오차가 크며 앙각이 높을수록 오차도 더욱 컸다.

A number of studies for the improvement of the accuracy of NNSS fix were carried out previously. But most studies were done when a ship was stationary at the fixed position. To investigate the accuracy of NNSS fix affected by the error of ship's speed and course when a ship was moving, the computer simulation was performed by each satellite, passing direction of satellite, and elevation angle. The obtained results are summarized as follows: 1. When elevation angle and passing direction of satellite were constant, there were little difference in the accuracy of NNSS fix from among those. 2. The accuracy of NNSS fox caused by the error of ship's speed was in proportion to the absolute value of it without regard to the magnitude of ship's speed, and it also became different according to the ship's course. 3. When the error of ship's speed was constant, the accuracy of the fixed position became different according to the passing direction of the satellite. 4. When the ship's course was south or north, the error of NNSS fix was greater than that of east or west, and the higher the elevation angle of the satellite, the greater the error of the NNSS fix.

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