Communications: directive radio wave systems and devices (e.g. – Aircraft collision avoidance system
Reexamination Certificate
2000-11-08
2001-08-21
Sotomayor, John B. (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Aircraft collision avoidance system
C342S030000, C342S036000, C342S046000, C342S049000
Reexamination Certificate
active
06278396
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to the field of avionics for collision avoidance systems (CAS). More specifically, the present invention relates generally to airborne traffic alert and collision avoidance systems and transponders.
Spurred by the collision of two airliners over the Grand Canyon in 1956, the airlines initiated a study of collision avoidance concepts. By the late 1980's, a system for airborne collision avoidance was developed with the cooperation of the airlines, the aviation industry, and the Federal Aviation Administration (FAA). The system, referred to as Traffic Alert and Collision Avoidance System II (TCAS II) was mandated by Congress to be installed on most commercial aircraft by the early 1990's. A chronology of the development of airborne collision avoidance systems can be found in “Introduction to TCAS II,” printed by the Federal Aviation Administration of the U.S. Department of Transportation, March 1990.
The development of an effective airborne CAS has been the goal of the aviation community for many years. Airborne collision avoidance systems provide protection from collisions with other aircraft and are independent of ground based air traffic control. As is well appreciated in the aviation industry, avoiding such collisions with other aircraft is a very important endeavor. Furthermore, collision avoidance is a problem for both military and commercial aircraft alike. In addition, a large, simultaneous number of TCAS interrogations from close-in formation aircraft members generate significant radio frequency (RF) interference and could potentially degrade the effectiveness of maintaining precise position/separation criteria with respect to other aircraft and obstacles. Therefore, to promote the safety of air travel, systems that avoid collision with other aircraft are highly desirable.
Referring to
FIG. 1
, there is shown a block diagram of a conventional TCAS system. Shown in
FIG. 1
are TCAS directional antenna
10
, TCAS omni-directional antenna
11
, and TCAS computer unit
12
, which includes receiver
12
A, transmitter
12
B, and processor
12
C. Also shown are aural annunciator
13
, traffic advisory (TA) display
14
, and resolution advisory (RA) displays
15
. Alternatively, the TA and RA displays are combined into one display (not shown). The transponder is comprised of transponder unit
16
A, control panel
16
B, and transponder antennas
16
C and
16
D. The TCAS and transponder operate together to function as a collision avoidance system. Those skilled in the art understand that this is merely illustrative of a conventional TCAS. For example, many other configurations are possible such as replacing omni-directional antenna
11
with a directional antenna as is known to those skilled in the art. The operation of TCAS and its various components are well known to those skilled in the art and are not necessary for understanding the present invention.
In a TCAS system, both the interrogator and transponder are airborne and provide a means for communication between aircraft. The transponder responds to the query by transmitting a reply that is received and processed by the interrogator. Generally, the interrogator includes a receiver, an analog to digital converter (A/D), a video quantizer, a leading edge detector, and a decoder. The reply received by the interrogator consists of a series of information pulses which may identify the aircraft, or contain altitude or other information. The reply is a pulse position modulated (PPM) signal that is transmitted in either an Air Traffic Control Radar Beacon System (ATCRBS) format or in a Mode-Select (Mode-S) format.
A TCAS II equipped aircraft can monitor other aircraft within approximately a 20 mile radius of the TCAS II equipped aircraft. (U.S. Pat. No. 5,805,111, Method and Apparatus for Accomplishing Extended Range TCAS, describes an extended range TCAS.) When an intruding aircraft is determined to be a threat, the TCAS II system alerts the pilot to the danger and gives the pilot bearing and distance to the intruding aircraft. If the threat is not resolved and a collision or near miss is probable, then the TCAS II system advises the pilot to take evasive action by, for example, climbing or descending to avoid a collision.
The TCAS 2000 is a TCAS-II system, which is currently in operation on many commercial and military aircraft. This system is very effective in providing midair collision avoidance in civil Air Traffic Control (ATC) airspace. TCAS was designed to provide effective midair collision avoidance in civil Air Traffic Control (ATC) airspace determining the range, altitude, and bearing with other aircraft equipped with Mode S/ATCRBS transponders. It monitors the trajectory of these aircraft for the purpose of determining if any of them constitute a potential collision hazard. The system is responsible for estimating the projected intruder track and determining if a potential conflict exists. If a conflict is detected, the system displays an advisory to the pilot. The system also provides guidance for vertical avoidance maneuver, known as Resolution Advisories (RAs). Complementary avoidance maneuvers between two TCAS equipped aircraft are ensured by automatic coordination of mutual intentions with the other aircraft through the Mode S transponders and associated TACS.
However, the TCAS 2000 originally was not designed to handle unique mission capabilities, which would be required, for example, by military aircraft. Examples of such unique mission capabilities are: operate in a tactical environment (tactical speed and dynamic maneuvers), perform highly dynamic, close-in formation flight, rendezvous, and air-refueling. At the same time, the system must effectively detect and avoid midair collision situation.
BRIEF SUMMARY OF THE INVENTION
The following summary of the invention is provided to facilitate an understanding of some of the innovative features unique to the present invention, and is not intended to be a full description. A full appreciation of the various aspects of the invention can only be gained by taking the entire specification, claims, drawings, and abstract as a whole.
The present invention comprises:
The Missionized Midair Collision Avoidance System (MCAS) of the present invention is an upgraded system which, preferably, is based upon Honeywell's new second generation Traffic Alert and Collision Avoidance System (TCAS) 2000. The present invention bridges the functional gaps, which will allow Navy and Marine Corps aircraft to operate in a tactical environment as effectively as in the air traffic management (ATM) environment. In order to distinguish between the tactical and ATM modes of an MCAS system, a preferable embodiment recommends that all MCAS functional capabilities can be allocated in two functional modules, the ATM module and Tactical module.
The ATM module contains the core TCAS 2000 functions, which can provide traffic advisory (TA) and resolution advisory (RA) capabilities for an aircraft to handle collision avoidance situation in the ATM environment. The ATM module is based on the TCAS 2000 system which currently complies with the Federal Aviation Administration (FAA) Technical Standard Order (TSO)—C119a. The ATM module is easily upgradeable to incorporate any of these changes in order to be compliant with future ATM requirements.
To minimize the certification process for TCAS related functions and to address specifically the operational requirements of aircraft, such as those used by the U.S. Navy and Marine Corps aircraft, all of the missionized capabilities required to operate in a tactical environment are allocated to the Tactical module. The module will work in conjunction with the ATM module to provide the following mission attributes: quick-time response, resistant to jamming and interference, and minimized detection beyond a short distance. The primary function of the Tactical module is to provide tactical traffic advisories, tactical traffic resolutions, display and control to support formation flight,
L-3 Communications Corporation
Sotomayor John B.
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