METHOD FOR AIR-TO-GROUND IFF

Abstract

A friend identification method includes steps of (a) targeting a specific ground location, (b) triggering an onboard Mark XIIA Mode 5 transponder, (c) issuing a reverse Mode 5 message to a responder, (d) receiving the reverse Mode 5 message at the responder, (e) decrypting the reverse Mode 5 message, and (f) responding to the reverse Mode 5 message if the specific ground location is within a predetermined radius from the responder.

Claims

1. A friend identification method comprising: targeting a specific ground location from a platform, with a weapon having a predetermined effects radius; triggering an onboard transponder; issuing an encrypted warning message from said platform, containing information identifying said platform and information about said target location to any responder near said location; receiving the warning message at said responder; decrypting the warning message at said responder; determining, at said responder, whether said target location is within said predetermined effects radius from the responder, and, if so, issuing from said responder to said transponder a response message to the warning message, said response identifying the responder as friendly.

2. The invention of claim 1, wherein the onboard transponder is a Mark XIIA Mode 5 transponder and the encrypted warning message is a reverse Mode 5 message.

3. The invention of claim 2, wherein said reverse Mode 5 message contains information about said predetermined effects radius.

4. The invention of claim wherein said response message contains formation including an identification of said platform.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawing, which is incorporated in and constitutes a part of the specification, illustrates an embodiment of the invention and together with the general description of the invention given above and the detailed description of the drawings given below, serve to explain the principles of the invention. The invention will now be described, by way of example, with reference to the accompanying drawing in which:

[0028] FIG. 1 is a depiction of the improved system.

DETAILED DESCRIPTION OF THE INVENTION

[0029] The present invention will be understood by reference to the following detailed description, which should be read in conjunction with the appended drawing. It is to be appreciated that the following detailed description of the embodiment is by way of example only and is not meant to limit, in any way, the scope of the present invention.

[0030] As shown diagrammatically in FIG. 1, operation of the Reverse Mode 5 capability begins when an aircraft 10, targeting a specific ground location 12, triggers an onboard Mark XIIA Mode 5 transponder 14 to issue a Mode 5 Level 2 Target Message 16.

[0031] The Reverse Mode 5 Target Message (interrogation) contains the attack coordinates, the weapon's effects radius (effective fragmentation radius) and the platform's identification number.

[0032] On the ground, at least one Reverse Mode 5 Responder 18 (Reverse Mode 5 receivers equipped on ground vehicles and/or dismounted soldiers) decodes, decrypts and authenticates the Target Messages and, using its own position data, determines whether it lies within the effects radius, measured from the position of the attack coordinates.

[0033] If a Responder determines that it is within the effects radius, it replies by generating a Response Message in the form of a Mode 5 Process Gain interrogation. This Response Message includes the targeting aircraft's identification number that was received in the Target Message.

[0034] Reverse Mode 5 capability is added to the transponder by an update software OFP (Operational Flight Program). This is a software and firmware update only. FIG. 1 shows a top level block diagram of the Reverse Mode 5-capable transponder. For Reverse Mode 5 operation the transponder will utilize the existing hardware interfaces for control, status and GPS information. However, the platform interface must be modified to include the signals shown on the left of Diagram 1. If Reverse Mode 5 is enabled and the platform locks onto a target area, the attack coordinates, effects radius and aircraft identification number are sent to the transponder over the platform interface. If a response is received from a ground responder, the transponder will use the platform aircraft's interface to communicate a don't shoot message to the platform mission computer. For this development, demonstration, and flight test effort the platform's Ethernet interface was modified to implement the Reverse Mode 5 functionality.

[0035] The hardware of the Reverse Mode 5-capable Transponder is not modified from the APX-123. This allows integration onto current aircraft with a Mode 5 Transponder without having to rewire the platform, add additional antennas, or occupy a weapon station to add this capability.

[0036] While the present invention has been described in connection with one embodiment, it is to be understood that other similar embodiments may be used or modifications or additions may be made to the described embodiment for performing the same function of the present invention without deviating therefrom. Therefore, the present invention should not be limited to any single embodiment, but rather construed in breadth and scope in accordance with the recitation of the appended claims.

[0037] While various embodiments of the present invention have been described in detail, it is apparent that various modifications and alterations of those embodiments will occur to and be readily apparent to those skilled in the art. However, it is to be expressly understood that such modifications and alterations are within the scope and spirit of the present invention, as set forth in the appended claims. Further, the invention(s) described herein is capable of other embodiments and of being practiced or of being carried out in various other related ways, In addition, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of including, comprising, or having, and variations thereof herein, is meant to encompass the items listed thereafter and equivalents thereof as well as additional items while only the terms consisting of and consisting only of are to be construed in a limitative sense.