The Evaluation of ARPA Information in the Effect of Fluctuating Target Positions

Koji Murai, Yuji Hayashi, Seiji Inokuchi

Abstract:	Automatic Radar Plotting Aids (ARPA) is one of the instruments effective for aiding safe navigation in term of collision avoidance, and ARPA information is calculated using a target’s position (ARPA position), own ship’s course and speed. The ARPA information are well utilized and highly appreciated among watch officers especially when the visibility is limited. However we should remember that the ARPA system is not complete yet. It still suffers transfer of target, lost target and other information mishap from time to time, and ARPA information is based on the past ARPA positions of targets. Here, ARPA position is a target position in ARPA system, which was decided from a radar echo signal. So it remains necessary to study on the accuracy of the ARPA information. In this report, we propose a simulation for the evaluation of reliability of ARPA information in the effect of fluctuating target positions on the estimated ARPA information, which are targets course and speed, CPA (Closest Point of Approach), TCPA (Time to CPA) etc., and analyze based on the distribution functions of the fluctuation of the collected 4 different target positions. Here, we also propose “Peak Position”, “Nearest Position”, “Center Position”, “Area Center Position” for 4 different target positions. And the results of 4 different target positions were compared with the accuracy requirement stipulated by IMO(5) (International Maritime Organization). It is recommend that “Nearest Position” is to be chosen as an APRA position. “Nearest Position” is the nearest point to own ship in the center line bisecting the echo signal, and a navigator usually use this point as a target position at radar observation. We worked on the collection of the radar echo signal data reflected from Training Ship FUKAE-MARU in Kobe University of Mercantile Marine (KUMM) at 18 aspect angles from 0 degree to 180 degrees in smooth sea condition off Marine Practice Center of KUMM in Awaji Island with 3cm (X band) and 10cm (S band) radar. And a distance to FUKAE-MARU is 2 and 4 nautical miles. The statistics of 4 target positions were obtained at 18 aspect angles using 63 scan data. Also, the received echo signals are processed by 8 bits, 120MHz A/D converter and stored in the 8 Mbytes memory to find basic statistical characteristics of the radar echo signal.
Published in:	Proceedings of the 2002 National Technical Meeting of The Institute of Navigation January 28 - 30, 2002 The Catamaran Resort Hotel San Diego, CA
Pages:	218 - 225
Cite this article:	Murai, Koji, Hayashi, Yuji, Inokuchi, Seiji, "The Evaluation of ARPA Information in the Effect of Fluctuating Target Positions," Proceedings of the 2002 National Technical Meeting of The Institute of Navigation, San Diego, CA, January 2002, pp. 218-225.
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In