Track
Update Concept Paper
The purpose of this concept paper is to discuss the track update component of a Radar Data Processing System (RDPS). The track update component will allow the RDPS to correctly update existing track information.
The track update component of the RDPS
provides the ability to update track information. This will be beneficial to the RDPS
system in that once a radar report can be correlated with an existing track,
the information related to the existing track can be updated without creating a
new track. Furthermore, the track
update component will provide the RDPS the ability to “coast” a track. This will ensure that new tracks are not
created when an aircraft reappears after being hidden from the radar for a
small number of radar sweeps by buildings or other obstacles. The track update
component depends on the adaptation data used to initialize the RDPS. The adaptation data provides the track
update component the amount of time between each update as well as the number
of track updates to create for a “coasting” track before the track is “coasted
out.”
The track update part of the RDPS will be responsible for the periodic generation of track updates. This part of the RDPS will also be responsible for the association of several data elements with the track update.
3.1 PERIODIC GENERATION OF A TRACK UPDATE
Once a track is established, the subsequent radar reports correlated with that track will be used for the generation of a track update. A track update should be done every 5 to 15 seconds. The length of time between each update will be determined by the adaptation data. When a track update is made, several data elements will be associated with the update. The data elements consist of the following:
Unique track identifier – a number that uniquely identifies the subject of the update, i.e., the track from which the “track update” has been derived. [Range: 0 <= unique track identifier < 1000]
Latitude – a number that indicates the latitude of the current track position with a precision of 1/10,000 of a degree of latitude. i.e., four decimal places. [Units: degrees of latitude, Range: -90.0000 <= latitude <= 90.0000]
Longitude – a number that indicates the longitude of the current track position with a precision of 1/10,000 of a degree of longitude. i.e., four decimal places. [Units: degrees of longitude, Range: -180.0000 <= longitude <= 180.0000]
Mode A SSR code status – same as the corresponding data element of a radar report.
Mode A SSR code – same as the corresponding data element of a radar report.
Mode C altitude status – same as the corresponding data element of a radar report.
Mode C altitude (pressure corrected) – same as the corresponding data element of a radar report, except that the pressure is corrected using the altimeter setting for a radar source.
MSAW status – an enumerated type with two values: “true” and “false.”
SCC status – an enumerated type with three values: “active,” “pending” and “false.”
MDC status – an enumerated type with two values: “true” and “false.”
Track quality – an enumerated type with three values: “active,” “coasting” and “coasted out.”
3.2 COASTING A TRACK
The RDPS will “coast” a track when radar reports are no longer correlated to the track. Track updates for a “coasting” track will be done by calculating the approximate location of the corresponding aircraft using its last known location, heading and speed. Except for latitude and longitude, which will be updated by the approximation, the remaining data elements associated with the track update remains unchanged. The track will remain in “coasting” status for three track updates.
After the coasting period, if no subsequent radar reports are correlated to the coasting track, the track will be “coasted out.” When the track is coasted out, the track will be terminated unless it is in Special Condition Code (SCC) alert state. If the track has been coasted out and it is in SCC alert state, the track will not be terminated until SCC alert state has been acknowledged by an operator or client system.
With the track update component in place, the RDPS will be able to update an existing track without creating a new track. This will also provide the RDPS the ability to maintain tracks which have been coasted.
The track update component enables the RDPS to update existing tracks and maintain coasted tracks.
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