US-12618646-B1 - Verification of desired target illumination in the presence of clutter for laser-designated applications

US12618646B1US 12618646 B1US12618646 B1US 12618646B1US-12618646-B1

Abstract

A laser seeker system is provided. The laser seeker system includes at least a laser pulse receiver circuitry and a pulse evaluator is provided. The pulse evaluator can be configured to obtain a set of measured pulse repetition intervals associated with laser pulses acquired by the laser pulse receiver circuitry. The pulse evaluator can further categorize a current volatility status indicating a respective category of a set of volatility categories, and based on a volatility index indicating a variance of the set of measured PRIs and a volatility counter indicating a number of the acquired laser pulses. The pulse evaluator can further increase a respective category counter that counts occurrences of the respective volatility category. The pulse evaluator can further categorize the authenticity of the laser seeker target based on the set of category counters.

Inventors

James H. Steenson, Jr.
Connor Minguy

Assignees

BAE SYSTEMS INFORMATION AND ELECTRONIC SYSTEMS INTEGRATION INC.

Dates

Publication Date: 20260505
Application Date: 20240905

Claims (20)

1 . A method of categorizing authenticity of a laser seeker target, comprising: obtaining a set of measured pulse repetition intervals (PRIs) associated with acquired laser pulses; categorizing a current volatility status of the laser seeker target, wherein the current volatility status indicates a respective volatility category of a set of volatility categories, and wherein the current volatility status is based on a volatility index and a volatility counter, the volatility index indicating a variance of the set of measured PRIs, and the volatility counter indicating a number of the acquired laser pulses; increasing a respective category counter of a set of category counters, wherein the set of category counters corresponds to the set of volatility categories and the respective category counter counts occurrences of the respective volatility category; and categorizing the authenticity of the laser seeker target based on the set of category counters.
2 . The method of claim 1 , further comprising: conveying target information to one or more assets, based on the categorized authenticity of the laser seeker target; and/or issuing a command to engage or not engage the laser seeker target, based on the categorized authenticity of the laser seeker target.
3 . The method of claim 1 , further comprising: obtaining an updated set of measured PRIs; categorizing a second volatility status of the laser seeker target, wherein the second volatility status indicates a second volatility category of the set of volatility categories, and wherein the second volatility status is based at least on an updated volatility index for the updated set of measured PRIs; increasing a second category counter of the set of category counters, wherein the second category counter counts occurrences of the second volatility category; and updating the categorization of the authenticity based on the increased second category counter.
4 . The method of claim 3 , further comprising decreasing the respective category counter.
5 . The method of claim 1 , wherein obtaining the set of measured PRIs comprises: receiving a set of measured pulse time of arrival (TOA) values; computing a pulse repetition interval (PRI) as a difference between a first pulse TOA value and a second pulse TOA value of the set of measured pulse TOA values; and adjusting the first pulse TOA value and/or the PRI to correct for a seeker timer overflow.
6 . The method of claim 5 , wherein: the first pulse TOA value corresponds to a TOA of a laser pulse reflected by the laser seeker target and received by a laser pulse receiver; and receiving the set of measured pulse TOA values comprises receiving, from the laser pulse receiver, the first pulse TOA value.
7 . The method of claim 1 , wherein the volatility index indicates a variance of a rolling average of the set of measured PRIs.
8 . The method of claim 1 , wherein the current volatility status indicates a currently determined likelihood that the laser seeker target is authentic, and the authenticity indicates a cumulative likelihood that the laser seeker target is authentic.
9 . The method of claim 1 , wherein the set of measured PRIs comprises a time series of measured PRIs.
10 . The method of claim 1 , wherein categorizing the current volatility status comprises: responsive to the volatility index being less than a first threshold value and the volatility counter being greater than a second threshold value, categorizing the current volatility status as the respective volatility category, wherein the respective volatility category denotes a likely authentic target; responsive to the volatility index being between the first threshold value and a third threshold value and the volatility counter being greater than the second threshold value, categorizing the current volatility status as the respective volatility category, wherein the third threshold value is greater than the first threshold value, and wherein the respective volatility category denotes a moderately likely authentic target; and responsive to the volatility index being at least the third threshold value or the volatility counter being at most the second threshold value, categorizing the current volatility status as the respective volatility category, wherein the respective volatility category denotes an unlikely authentic target.
11 . A non-transitory computer readable medium storing instructions that when executed by one or more processors cause a process to be carried out for categorizing authenticity of a laser seeker target, the process comprising: obtain a set of measured pulse repetition intervals (PRIs) associated with acquired laser pulses; categorize a current volatility status of the laser seeker target, wherein the current volatility status indicates a respective volatility category of a set of volatility categories, and wherein the current volatility status is based on a volatility index and a volatility counter, the volatility index indicating a variance of the set of measured PRIs, and the volatility counter indicating a number of the acquired laser pulses; increase a respective category counter of a set of category counters, wherein the set of category counters corresponds to the set of volatility categories and the respective category counter counts occurrences of the respective volatility category; categorize the authenticity of the laser seeker target based on the set of category counters; and convey target information to one or more assets, based on the categorized authenticity of the laser seeker target.
12 . The non-transitory computer readable medium of claim 11 , the process further comprising to: obtain an updated set of measured PRIs; categorize a second volatility status of the laser seeker target, wherein the second volatility status indicates a second volatility category of the set of volatility categories, and wherein the second volatility status is based at least on an updated volatility index for the updated set of measured PRIS; increase a second category counter of the set of category counters, wherein the second category counter counts occurrences of the second volatility category; and update the categorization of the authenticity based on the increased second category counter.
13 . The non-transitory computer readable medium of claim 11 , wherein to obtain the set of measured PRIs comprises: to receive a set of measured pulse time of arrival (TOA) values; and to compute a pulse repetition interval (PRI) as a difference between a first pulse TOA value and a second pulse TOA value of the set of measured pulse TOA values.
14 . The non-transitory computer readable medium of claim 11 , wherein the volatility index comprises a variance of a rolling average of the set of measured PRIs.
15 . A laser seeker system configured to categorize authenticity of a laser seeker target, the laser seeker system comprising: a selected pulse evaluator configured to: obtain a set of measured pulse repetition intervals (PRIs) associated with laser pulses acquired by a laser pulse detector and/or a laser pulse selector; categorize a current volatility status of the laser seeker target, wherein the current volatility status indicates a respective volatility category of a set of volatility categories, and wherein the current volatility status is based on a volatility index and a volatility counter, the volatility index indicating a variance of the set of measured PRIs, and the volatility counter indicating a number of the acquired laser pulses; increase a respective category counter of a set of category counters, wherein the set of category counters corresponds to the set of volatility categories and the respective category counter counts occurrences of the respective volatility category; categorize the authenticity of the laser seeker target based on the set of category counters; and issue a command to engage the laser seeker target, based on the categorized authenticity of the laser seeker target.
16 . The laser seeker system of claim 15 , wherein the selected pulse evaluator is further configured to: obtain an updated set of measured PRIs; categorize a second volatility status of the laser seeker target, wherein the second volatility status indicates a second volatility category of the set of volatility categories, and wherein the second volatility status is based at least on an updated volatility index for the updated set of measured PRIS; increase a second category counter of the set of category counters, wherein the second category counter counts occurrences of the second volatility category; and update the categorization of the authenticity based on the increased second category counter.
17 . The laser seeker system of claim 15 , wherein to obtain the set of measured PRIs comprises: to receive, from the laser pulse detector and/or the laser pulse selector, a set of measured pulse time of arrival (TOA) values; and to compute a pulse repetition interval (PRI) as a difference between a first pulse TOA value and a second pulse TOA value of the set of measured pulse TOA values.
18 . The laser seeker system of claim 17 , wherein the selected pulse evaluator is further configured to adjust the first pulse TOA value and/or the PRI to correct for a seeker timer overflow.
19 . The laser seeker system of claim 15 , wherein the volatility index indicates a variance of a rolling average of the set of measured PRIs.
20 . The laser seeker system of claim 15 , wherein to categorize the current volatility status further comprises: responsive to the volatility index being less than a first threshold value and the volatility counter being greater than a second threshold value, to categorize the current volatility status as the respective volatility category, wherein the respective volatility category denotes a likely authentic target; responsive to the volatility index being between the first threshold value and a third threshold value and the volatility counter being greater than the second threshold value, to categorize the current volatility status as the respective volatility category, wherein the third threshold value is greater than the first threshold value, and wherein the respective volatility category denotes a moderately likely authentic target; and responsive to the volatility index being at least the third threshold value or the volatility counter being at most the second threshold value, to categorize the current volatility status as the respective volatility category, wherein the respective volatility category denotes an unlikely authentic target.

Description

BACKGROUND When a pulsed laser beam is used to designate, identify, or range-find a target or other object, reflections of the laser pulse off of the target can be detected by a laser pulse receiver, which may assign a relative or absolute time-of-arrival (TOA) of the pulse. The TOA may be related to the pulse's time-of-flight (TOF) from the laser pulse emitter to the target, and its return TOF to the receiver (the total laser path distance, or TLPD), at the speed of light through the medium(s) through which the pulse is traveling. An expected TOA of the next pulse can be determined if the firing interval between successive laser pulses is known, even if not at a consistent rate, and if changes in the TLPD can be assumed or anticipated. However, complicating factors can occur, which can result in laser pulse reflections being received from objects other than the intended target. Such reflections are referred to as “clutter” and can result from a laser pulse over-spilling or under-spilling, particulate suspended within the medium, and the like. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 schematically illustrates a laser seeker environment, including a laser designator configured to transmit laser pulses and a laser receiver configured to receive and process the pulses reflected from objects in the environment, in accordance with an example of the present disclosure. FIG. 2 is a block diagram illustrating components of a semi-active laser seeker, in accordance with an example of the present disclosure. FIGS. 3A-3B illustrate results from example trials, in accordance with an example of the present disclosure. FIG. 4A is a flow diagram illustrating a method to categorize authenticity of a laser seeker target, in accordance with an example of the present disclosure. FIG. 4B is a flow diagram illustrating a method to categorize authenticity of a laser seeker target, in accordance with an example of the present disclosure. FIG. 4C is a flow diagram illustrating a method to categorize authenticity of a laser seeker target, in accordance with an example of the present disclosure. FIGS. 5A-5E are flow diagrams illustrating details of a method to categorize authenticity of a laser seeker target, in accordance with an example of the present disclosure. FIG. 6 a flow diagram illustrating details of a method to categorize authenticity of a laser seeker target, in accordance with an example of the present disclosure. DETAILED DESCRIPTION Techniques are disclosed for categorizing authenticity of laser seeker targets. Example categories of authenticity may include, for instance, likely authentic, moderately likely to be authentic, and unlikely to be authentic. Other examples may include fewer or more such categories (e.g., highly likely to be authentic, and highly unlikely to be authentic, are two additional examples). An example scenario where the techniques may be helpful is the case where there are multiple objects (targets) within the field of view (FOV) of a laser seeker, with one of the objects being a true target (e.g., an adversarial drone or projectile) and the other objects being false targets (e.g., clutter). The laser seeker may be, for example, part of a projectile (e.g., laser guided missile) or a tracking system (e.g., unmanned aerial vehicle, or UAV), or a combination of these two, and is configured to illuminate objects within its FOV with laser light, which is in turn reflected back to the seeker. The laser seeker is further configured to analyze those reflections and discern the true target from false targets. A true target can be assigned, for instance, to the category of likely authentic or moderately likely to be authentic, and a false target can be assigned to the category of unlikely to be authentic. As a given engagement between the seeker and an object continues over time (allowing for collection of more reflections), the authenticity category assigned to that object can be updated and refined. The assigned authenticity category can then be used to inform mission planning, such as the example case where the laser seeker system can use the assigned authenticity category to make a determination as to whether or not to engage an object with a given asset (e.g., a munition). The laser seeker may, for example, issue a command to engage the laser seeker target, based on the laser seeker target categorized as being likely to be authentic; or issue a command to not engage the laser seeker target, based on the laser seeker target categorized as being unlikely to be authentic. An example method includes obtaining a set of measured pulse repetition intervals (PRIs) associated with reflected laser pulses from one or more objects within a given FOV, and assigning a volatility status to those objects. The volatility status assigned corresponds to one of two or more authenticity categories (e.g., highly likely to be authentic, likely authentic, moderately likely to be authentic, unlikely to be authentic, and highl