PROPOUSES OF PLOTTING.
- Whether danger of collision exist
- Calculate CPA,TCPA and relative motion lines
Possible error sources in manual plotting
- Error in bearing
- Error in range
- Error in time between plots
- Low relative speed
- Error in own ship speed
- Error in own sip heading
- Error due own ship manouvering
METHODS OF PLOTTING
1. IN TRUE MOTION: True combination of true motion and speed. True direction of motion of a target expressed as an angular displacement of north.
2.IN RELATIVE MOTION: The direction of a motion of a target, relative to own ship position expressed as an angular displacemen from north.
The Plotting process include:
DETECTION: recognition of presence that a target.
SELECTION: choose of a target
TRAKING: the computer process of observing the sequential changes in the position of a target, in order to stablish its motion.
Fuente: Modulo de Introduccion al ARPA publicado por SEAGULL and MACROMEDIA