METHODS OF ACCESSING A NAVIGATION DATABASE

• US 20120036124A1
• Filed: 12/04/2009
• Published: 02/09/2012
• Est. Priority Date: 12/05/2008
• Status: Active Grant

• Current Assignee: Thales SA
• Original Assignee: Thales SA
• Inventors: Gamet, Pierre, Chaix, Philippe
• Granted Patent: US 8,478,752 B2
• Time in Patent Office: Days
• US Class Current: 707/724
• CPC Class Codes: G06F 16/29 Geographical information databases

Abstract

A navigation database comprises a first set of elements comprising airports, beacons and waypoints; a second set of elements comprising procedures; and a third set of elements comprising routes. The method comprises a step of creating a pair of indices comprising an index comprising the elements of the three sets; identifier, a type and a functional identifier; a first list of pointers to the memory address where the elements are stored; a pre-index comprising a list of code, each code corresponding to the first characters of each element, the codes being indexed by a family of attributes of elements; a second list of pointers to the identifier of the first element in the first index.

Claims

1. A method of accessing a navigation database by means of an onboard computer, the navigation database being integrated into a navigation system for aircraft comprising said computer, the navigation database comprising:

a first set of elements, called Fix values, comprising notably representations of airports, beacons and waypoints, as well as the geographical coordinates of said Fix values;

a second set of elements comprising procedures, each procedure being defined by a succession of transitions, the transitions comprising a set of maneuvers of the aircraft, the maneuvers being instructions predefined in the navigation system;

a third set of elements comprising representations of routes formed by a succession of waypoints and/or of airports, the method comprising;

creating a first alphanumeric index comprising;

the elements of the first, second and third set;

attributes of each element, the attributes comprising at least the identifier, the type and the functional identifier of said element;

a first list of pointers, each pointer being associated with an element, designating the memory address where the elements are stored in the navigation database,

the first alphanumeric index being ordered according to at least one type of attribute, called AT_ORD, and

creating an alphanumeric pre-index comprising;

a list of codes, each code being unique and corresponding to the first characters of each of the data of the AT_ORD of each element of the navigation database;

a second list of pointers, each pointer being associated with a code and pointing at the identifier, in the first index, of each first element whose AT_ORD comprises the associated code.

2. The method of accessing a navigation database according to claim 1, the navigation database further comprising:

a fourth set of elements, the elements comprising representations of the geographical cells covering a determined expanse, the cells being tagged by geographical coordinates, the cells comprising a list of elements of the first set, and

the method further comprising;

creating a second geographical index comprising;

a list of the geographical cells;

a third list of pointers, each cell being associated with a pointer, to the memory address where the geographical cells are stored in the database;

the size of each list.

3. The method according to claim 1, wherein a set of pairs comprising a first index and a pre-index is created, each of the pairs of indices being ordered according to at least one type of attribute of an element of the navigation database.

4. The method according to claim 1, wherein the codes of the list of codes correspond to the first two characters of each of the data of the AT_ORD of each element of the navigation database.

5. The method according to claim 1, wherein the codes of the list of codes correspond to the first three characters of each of the data of the AT_ORD of each element of the navigation database.

6. The method according to claim 1, further comprising:

creating a starting key as header of the database readable by a computer of the navigation system.

7. The method according to claim 3, wherein

a first linear search for the first characters in the elements of the pre-index determines the memory addresses of the identifiers of the first and of the last elements corresponding in the first index;

and

a second dichotomy search through a list of elements of the first index corresponding to the search criterion determines the memory address of the criterion in the navigation database.