Telecommunications – Transmitter and receiver at separate stations – Having diverse art device
Reexamination Certificate
2000-11-27
2003-02-18
Crosland, Donnie L. (Department: 2632)
Telecommunications
Transmitter and receiver at separate stations
Having diverse art device
C455S067150, C455S431000, C701S014000, C701S035000, C340S945000, C340S870030, C340S870030, C375S219000
Reexamination Certificate
active
06522867
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates in general to communication systems, and is particularly directed to an aircraft data communication system having a plurality of wireless ground links that link respective aircraft-resident subsystems, in each of which a copy of its flight performance data is stored, with airport-located ground subsystems, each ground subsystem being coupled, in turn, by way of respective telco links to a remote flight operations control center, where flight performance data from plural aircraft parked at different airports may be analyzed and from which the uploading of in-flight data files may be directed by airline systems personnel.
BACKGROUND OF THE INVENTION
Modern aircraft currently operated by the commercial airline industry employ airborne data acquisition (ADA) equipment, such as a digital flight data acquisition unit (DFDAU) as a non-limiting example, which monitor signals supplied from a variety of transducers distributed throughout the aircraft, and provide digital data representative of the aircraft's flight performance based upon such transducer inputs. As flight performance data is obtained by the acquisition equipment, it is stored in an attendant, physically robust, flight data recorder (commonly known as the aircraft's “black box”), so that in the unlikely event of an in-flight mishap, the flight data recorder can be removed and the stored flight performance data analyzed to determine the cause of the anomaly.
In a further effort to improve aircraft safety, rather than wait for an accident to happen before analyzing flight recorder data, the Federal Aviation Administration (FAA) has issued a draft advisory circular AC-120-XX, dated Sep. 20, 1995, entitled “Flight Operational Quality Assurance Program” (FOQA), which recommends that the airlines look at the information provided by the digital flight data acquisition unit at regular intervals.
One suggested response to this recommendation is to equip each aircraft with a redundant flight data recording unit having a removable data storage medium, such as a floppy disc. Such an auxiliary digital data recorder is intended to allow aircraft safety personnel to gain access to the flight performance data by physically removing the auxiliary unit's data disc, the contents of which can then be input to an aircraft performance analysis data processing system for evaluation.
Although installing such a redundant flight data recording unit allows airline personnel to retrieve a copy of the flight performance data for subsequent evaluation, when considering the large volume of aircraft traffic experienced by major commercial airports, the above-proposed scheme is not only extremely time and manpower intensive, but is prone to substantial misidentification and aircraft/data association errors.
Other proposals, described in U.S. Pat. No. 5,359,446, are to use either a direct line-of-sight infrared link or a fiber optic cable to couple an on-board aircraft computer system with a ground-based computer system. Obvious drawbacks to these systems are the fact that not only do they employ complex and expensive components, but require that the aircraft be parked at the gate, so that the line-of-sight infrared transceivers or the fiber optic connection assemblies can be properly interlinked. As a consequence, neither of these types of systems is effective for use with commuter, cargo or military aircraft, which are customarily parked on an apron, rather than at a mating jetway, where such an optical link is to be provided.
SUMMARY OF THE INVENTION
In accordance with the present invention, the above-described objective of periodically analyzing flight performance data, without having to physically access a redundant unit on board the aircraft, is successfully addressed by means of a wireless ground data link, through which flight performance data provided by airborne data acquisition equipment is stored, compressed, encrypted and downloaded to an airport-resident ground subsystem, which forwards flight performance data files from various aircraft to flight operations control center for analysis. For purposes of providing a non-limiting example, in the description of the present invention, the data acquisition equipment will be understood to be a DFDAU.
For this purpose, an auxiliary data path is coupled from the DFDAU in parallel with the flight data recorder to a bidirectional radio frequency (RF) carrier-based ground data link (GDL) unit, that is installed in the avionics compartment of the aircraft. The GDL unit is operative to communicate with an airport-resident ground subsystem via the RF communications ground link infrastructure.
In accordance with a preferred embodiment of the invention, this wireless ground data link is implemented as a spread spectrum RF link. Numerous different frequency bands can be used in the present invention, as known to those skilled in the art. For example, several bands do not require an FCC site license. These bands include the 900 MHz, 2.4 GHz and 5.0 GHz bands. One particularly used band has been found to have a reasonably wide (about 100 MHz) unlicensed 2.4 to 2.5 GHz S-band segment, which provides global acceptance. Throughout the description, it should be understood that any frequency band can be used with the present invention. The description proceeds, however, with reference to the use of the 2.4 to 2.5 GHz band, which is known to have global acceptance. A benefit of spread spectrum modulation is its inherently low energy density waveform properties, which are the basis for its acceptance for unlicensed product certification. Spread spectrum also provides the additional benefits of resistance to jamming and immunity to multipath interference. Although throughout this description the use of direct sequence spread spectrum is described in detail, it should be understood that frequency hopping also can be used because of its advantages in spread spectrum, as well as chirp modulation. A forward error correction that does not use a pseudo ransom sequence can also be used. Well known M block modulation techniques can also be used. These types of modulations are well known to those skilled in the art.
A principal function of the GDL unit is to store a compressed copy of the (ARINC 717) flight performance data generated by the DFDAU and supplied to the aircraft's flight data recorder. The GDL unit is also configured to store and distribute auxiliary information uploaded to the aircraft from a wireless router (as directed by the remote operations control center) in preparation for its next flight. The uploaded information may include audio, video and data, such as flight navigation information, and digitized video and audio files that may be employed as part of an in-flight passenger service/entertainment package. The GDL unit may also be coupled to an auxiliary printer that is ported to the GDL unit in order to enable an immediate hard copy of flight data information (e.g. exceedences of parameter data) to be provided to the crew immediately upon the conclusion of the flight.
Once an aircraft has landed and is within communication range of the ground subsystem, the wireless router receives flight performance data via the wireless ground data link from an aircraft's GDL unit. It also supplies information to the aircraft in preparation for its next flight. The wireless router receives flight files from the aircraft's GDL unit and forwards the files to an airport base station, which resides on the airport's local area network (LAN).
The airport base station forwards flight performance data files from various aircraft by way of a separate communications path such as a telephone company (telco) land line to a remote flight operations control center for analysis. The airport base station automatically forwards flight summary reports, and forwards raw flight data files, when requested by a GDL workstation.
The flight operations control center, which supports a variety of airline operations including flight operations, flight safety,
Wright Thomas H.
Ziarno James J.
Crosland Donnie L.
Harris Corporation
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