Historical information is accumulated and used to predict future position for use with air traffic control, threat estimation, combat system doctrine, gun aiming, missile guidance, and torpedo delivery.
A tracker needs to go through four phases of updates: Each track typically has a position, heading, speed, and a unique identifier.
This was necessary to eliminate limitations that include mid-air collisions and other problems linked with obsolete equipment that was socialized by PATCO and United States Department of Defense.
Modern civilian air traffic and military combat systems depend upon a custom track algorithms used with real-time computing slaved to displays and peripherals.
Users are generally presented with several displays that show information from track data and raw detected signals.
Users have a pointing device with several buttons that provides access to the track file through the Plan Position Indicator.
Each new detection reported from incoming sensor data is fed into the track algorithm, which is used to drive displays.
A 4D radar with a pencil beam will produce radial Doppler velocity in addition to bearing, elevation, and slant range.
Drop data may sometimes be extracted from main memory and recorded onto storage media along with the track file for offsite analysis.
Capture processing takes place only after stored sensor data has been compared with all existing tracks.
As an example, a capture distance of 10 miles require periodic scans no more than 15 seconds apart in order to detect vehicles traveling at mach 3.
This strategy produces a large number of false tracks due to clutter near the horizon and in the viscidity of weather phenomenon and biologicals.
Birds, insects, trees, waves, and storms generate enough sensor data to slow down the track algorithm.
Systems that lack MTI must reduce receiver sensitivity or prevent transition to track in heavy clutter regions.
Lock and radial velocity are unique requirement for Doppler sensors that add additional layers of complexity to the track algorithm.
Invalid reflections include things like helicopter blades, where Doppler does not correspond with the velocity that the vehicle is moving through the air.
Invalid signals include microwaves made by sources separate from the transmitter, such as radar jamming and deception.
This means the feedback loop must be opened for objects like helicopters because the main body of the vehicle can be below the rejection velocity (only the blades are visible).
The coriolis effect can be used to determine the distance to this line when the object maintains constant speed during a turn.
Bombs produce a single impulse, and the location can be identified by comparing the time of arrival as the shock wave passes over 3 or more sensors.
The shock wave from the projectile arrives before the muzzle blast for inbound fire, so both signals must be paired by the tracking algorithm.
All new sensor data is compared with existing tracks first before capture or drop processing takes place.
XYZ velocity is determined by subtracting successive values and dividing by the time difference between the two scans.
Track data is usually recorded in the event that an investigation is required to establish the root cause for an aircraft loss.