Communications: directive radio wave systems and devices (e.g. – With particular circuit – Display
Reexamination Certificate
2001-04-13
2002-10-22
Tarcza, Thomas H. (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
With particular circuit
Display
C342S182000, C342S183000, C340S961000
Reexamination Certificate
active
06469660
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to the field of air traffic display systems. More particularly, the invention includes a method and system for depicting an aircraft or a ground vehicle on a display using a target icon which is correlated to the integrity of the incoming data describing the vehicle's position and track.
BACKGROUND OF THE INVENTION
Since the dawn of aviation, pilots and aircraft designers alike have continually sought new and better ways to augment and enrich the pilot's own sensory perception with a variety of on-board and ground-based equipment. For safe flight, pilots need information about the flight path and the environment in which his or her own ship is flying. Flight path data includes position, track, speed, and other navigational data, as well as a variety of information from the pilot's ownship, as it is called. Environmental data includes information about the weather, the terrain, and the position and track of other aircraft in the vicinity.
The purpose of ownship equipment is to provide an aid to visual acquisition, conflict detection, threat assessment, and conflict avoidance. Advances in aviation technology have vastly increased the amount of information that can be provided to pilots. Multi-function cockpit displays such as a Cockpit Display of Traffic Information (CDTI) may depict a wide variety of data, such as air traffic, ground traffic, weather, and terrain, at different times and in different combinations, using a single screen.
The CDTI is a means of presenting surveillance information about the surrounding traffic to the flight crew. Traffic includes aircraft as well as ground vehicles or fixed obstructions. The information presented includes the relative position of a target of interest. The term “target” refers to traffic that is nearby the ownship and may be of interest to the flight crew and other CDTI users. Target data for the CDTI may be obtained from a variety of sources, including Automatic Dependent Surveillance—Broadcast (ADS-B). Targets typically are represented by displaying a selected icon on the CDTI.
One challenge presented by the wide variety of data available for display on a CDTI is the fact that different data may possess different levels of integrity. In this context, integrity is related to the probability that the true location of an aircraft is outside a certain volume of space defined by a containment boundary that surrounds the three-dimensional position being broadcast. A first aircraft, for example, may be broadcasting its three-dimensional position with high integrity, whereas the data being broadcast by a second aircraft may have much lower integrity. Displaying both aircraft with the same icon may create the false impression that the data supporting the position has equal integrity.
High-integrity air traffic data is desired for safe flight, especially given the increase in air traffic worldwide. The integrity of the data about a particular target depends on several factors, including the timeliness of the latest data transmission and the accuracy of the position data within the signal transmitted.
Different applications that make use of the traffic data on a CDTI require different levels of data integrity. Target data may be used and processed in a variety of applications including, for example, a Conflict Situational Awareness (CSA) application and a Range Monitoring (RM) application. Some applications require and use only traffic data having a sufficiently high integrity.
Target data integrity may also vary over time, depending on the characteristics of a particular transmission. Data signal quality can improve or degrade due to satellite positions, sensor positioning, or sporadic signal reception. In some instances, the integrity of the ownship's position data may degrade, thereby affecting the ability of onboard applications to accurately monitor the traffic situation.
Thus, there is a need to raise the awareness of pilots and other users of air traffic monitoring data to the integrity of the data supporting a target being displayed. There is a related need to raise the awareness of pilots to changes in data integrity.
There is also a need for differentiating between high-integrity and lower-integrity target data to indicate which targets are suitable for use by a particular application.
There is still further a need for updating the traffic icon if and when the target data's integrity changes.
SUMMARY OF THE INVENTION
The above and other needs are met by the present invention which, in one embodiment, provides a method for determining the integrity of incoming target data and provides a system for assigning and displaying a target icon that is correlated to reflect the target data's integrity. In a preferred embodiment, the invention provides a set of target icons which are correlated to target data integrity. Such a set of icons should be capable of varying in color, size, shape, and/or other characteristics such as being outlined or filled, or flashing or still, to reflect the target data's integrity.
It should be understood that integrity includes both an accuracy aspect and a timeliness aspect. Data from a target will not be assigned a high integrity unless it is both accurate and recent. Accurate position data must be recent to be reliable. Likewise, recent position data must also be accurate to be reliable. In one aspect of the invention, the system compares the current time to the time of measurement of the incoming position data.
Integrity is related to the probability that the true position of an aircraft is outside an imaginary volume of space (defined by a containment boundary) which surrounds the three-dimensional position being broadcast. If the probability that the true position is outside the containment boundary is high, then the data accuracy is low and, therefore, the integrity of the position data is low. Conversely, if the probability that the true position is outside the containment boundary is low, then the data accuracy is high and, accordingly, the integrity of the position data is high.
Components of the System
According to another aspect, the system of the present invention comprises a computer or other automated system for processing and implementing the rules described herein in order to display accurate and timely data on a cockpit display. In one preferred embodiment, the system itself is housed within a Link and Display Processor Unit (LDPU) which serves as the data link between the signals received and the icons displayed.
In one preferred embodiment, the system of the present invention is in communication with a plurality of signal receivers, an LDPU, and a Cockpit Display of Traffic Information (CDTI). Each signal receiver is configured to receive a particular type of signal and communicate the data received to the LDPU. One or more signal receivers may be housed within the LDPU itself. Through the signal receivers, position data is received about a plurality of targets.
The system of the present invention is capable of processing ADS-B signals broadcast by targets of interest and is also capable of interpreting other types of signals. An ADS-B (Automatic Dependent Surveillance—Broadcast) signal includes a variety of indicators, typically including a Type Code, a time of applicability, a pressure altitude, a latitude, and a longitude.
The Type Code indicates the type of message being broadcast and serves as an accuracy indicator of the data to follow. The Type Code may be used to determine a value for the Navigational Uncertainty Category for Position (NUCp). The NUCp value indicates a level of accuracy of the latitude and longitude coordinates included in the ADS-B position message. For a target broadcasting a transponder signal instead of an ADS-B signal, a Type Code may be calculated and then used to determine the NUCp value.
The time of applicability embedded within the ADS-B signal represents the time when the position measurement was made.
Integrity Monitoring
One aspect of the present invention include
Grove Robert M.
Horvath Steve
Pratt John T.
Alston & Bird LLP
Andrea Brian K
Tarcza Thomas H.
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