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Inertial navigation unit protocol converter

Inertial navigation unit protocol converter description/claims

1. Field of the Invention

The present invention relates generally to the field of protocol converters. More specifically, the present invention relates to a protocol converter for use with an inertial navigation unit on the P-3 aircraft.

2. Description of the Prior Art

The Department of Homeland Security utilizes airborne surveillance operations to monitor illegal activities which have an impact on national security. These activities include drug trafficking, illegal immigration, and terrorist activities.

Many ride-along sensor units often deployed with a surveillance P-3 aircraft require the implementation the National Marine Electronics Association 0183 (NMEA-0183) serial navigation data format. Future proposed components for geospatial video recording and reproduction also require the ability to utilize this format. There is currently an immediate need to provide aircraft navigation data in real time to produce a coherent video data stream for situational awareness during the transport of sensor video to the ground for analysis. The NMEA-0183 protocol provides a low bandwidth, commonly utilized format that end users can easily make use of for situational awareness.

There are several ARINC-429 to NMEA-0183 protocol converters which are commercially available. None of these converters are specifically designed to utilize the wide variety of parameters available from the Litton LTN-92 Inertial Navigation System (INS), used on the P-3 aircraft, which is manufactured by Litton Industries, Incorporated. These protocol converters extract only the most commonly used parameters from the ARINC-429 protocol (such as time, position, ground speed and heading) and output only a small fixed set of NMEA-0183 sentences (such as RMB, RMC, GGA and GSA). None of the NMEA-0183 sentences provided by these protocol converters are capable of providing pointing information that is used to indicate the location of an object relative to the P-3 aircraft.

Accordingly there is a need for a protocol converter that generates a custom sentence which includes pointing information that is used to indicate the location of an object relative to the P-3 aircraft.

The invention relates to an Inertial Navigation Unit (INU) Protocol Converter that translates the ARINC-429 protocol output of a Litton LTN-92 Inertial Navigation System (INS) to the National Marine Electronics Association 0183 (NMEA-0813) protocol. The protocol converter comprises one commercially available ARINC-429 interface board with cable and software operating in a computer with at least one serial communications port and running the Microsoft Windows 2000 or Microsoft Windows XP operating system. The ARINC-429 interface board utilized in this invention is the CEI-520A-44 interface board manufactured by Condor Engineering, although any ARINC-429 interface board could be adapted for this use. The protocol conversion program software comprises two files (INU_Convert.exe, and INU_Convert.ini). INU_Convert.exe is the executable program that performs the protocol conversion. INU_Convert.ini is an initialization file used by the executable at startup to initialize its configuration.

The protocol conversion program is installed to start upon computer startup and appears as a small P-3 aircraft icon in the operating system's system tray. The user can expand this icon to view the status of the ARINC-429 and serial communications interfaces as well as change the configuration of the protocol conversion program. This protocol conversion program is capable of outputting the NMEA-0183 protocol to as many as four serial communications ports simultaneously. The protocol conversion program is also capable of outputting any combination of nine NMEA-0183 sentences, one of which is a custom sentence that contains aircraft position, orientation and pointing information to a waypoint, destination or target location entered by the user.

FIG. 1 illustrates a communications flow diagram for the inertial navigation unit protocol converter comprising the present invention;

FIG. 2 is a computer generated display of the ARINC-429 data and status and the status of the NMEA-0183 interface;

FIG. 3 is the start program dialog routine for the protocol conversion program used with the inertial navigation unit protocol converter of FIG. 1;

FIG. 4 is the InitializeSerialCommDialog routine for the protocol conversion program used with the inertial navigation unit protocol converter of FIG. 1;

FIG. 5 is the InitializePortSelections routine for the protocol conversion program used with the inertial navigation unit protocol converter of FIG. 1;

FIG. 6 is the InitializeSerialCommPorts routine for the protocol conversion program used with the inertial navigation unit protocol converter of FIG. 1;

FIG. 7 is the InitializeSerialCommPort(n) routine for the protocol conversion program used with the inertial navigation unit protocol converter of FIG. 1;

FIG. 8 is the ArincInput Thread routine for the protocol conversion program used with the inertial navigation unit protocol converter of FIG. 1;

• Provisional Patent
• Utility Patent

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