Laser-aided passive seeker
View Patent ↗A system to merge and exploit two uniquely different types of seeker homing modes of functionality into a single, dual-mode seeker, using only an FPA as the active sensor to achieve both modes of operation. The disclosed embodiments also provide a means to actively designate & track, and also passively track the same target between active designation pulses to track a target at an update rate higher than the designator pulse rate with less demanding automatic target tracking algorithms. The disclosed embodiments eliminate the need for automatic target acquisition/recognition algorithms necessary for purely passive target tracking. The passive tracking methodology “aids” the passive tracking algorithm, based on frame-to-frame image registration, with active SAL track information to improve overall seeker guided weapon performance.
1. A laser-aided semi-passive seeker comprising:
a semi-active laser seeker having an imager configured to detect and decode laser-based energy and image ambient energy;
said imager further configured to generate at a first predefined rate a sequence of semi-active laser-based images containing a laser spot illuminating a target;
said imager said imager further configured to generate at a second predefined rate a sequence of passive ambient-energy images containing said target without said laser spot;
a laser-aided semi-passive tracker configured to receive said sequence of semi-active laser-based images at said first predefined rate;
said laser-aided semi-passive tracker further configured to receive said sequence of passive ambient-energy images at said second predefined rate;
said laser-aided semi-passive tracker further configured to process an image pair comprising one of said sequence of semi-active laser-based images received within a predetermined time of one of said sequence of passive ambient-energy images in order to map laser spot coordinates of said laser spot of said one of said sequence of semi-active laser-based images to said one of said sequence of passive ambient-energy images; and
said laser-aided semi-passive tracker further configured to track said laser spot coordinates on said sequence of passive ambient-energy images that are not received by said laser-aided semi-passive tracker within said predetermined time of said one of said sequence of said semi-active laser based images.
2. The seeker of claim 1 wherein said predetermined time comprises less than about 10 milli-seconds.
3. The seeker of claim 1 further comprising an image registration stage configured to register said sequence of active laser-based images with said sequence of passive images.
4. The seeker of claim 3 wherein said image registration stage registers said sequence of active laser-based images with said sequence of passive images by a frame-to-frame image registration.
5. The seeker of claim 1 wherein said laser-aided semi-passive tracker tracking said laser spot coordinates on said sequence of passive ambient-energy images that are not received by said laser-aided semi-passive tracker within said predetermined time of said one of said sequence of said semi-active laser based images designates said target for semi-passive tracking of said target.
6. The seeker of claim 1 wherein said said laser-aided semi-passive tracker automatically reverts to a passive-only homing mode if receipt of said laser spot coordinates is discontinued.
7. A computer implemented method of laser-aided semi-passive tracking comprising:
detecting and decoding, using a processor system, laser-based energy and image ambient energy at a single imager;
generating, using said processor system, from said imager at a first predetermined rate a sequence of semi-active laser-based images containing a laser spot illuminating a target;
generating, using said processor system, from said imager at a second predetermined rate a sequence of passive ambient energy-based images containing said target without said laser spot;
receiving at a laser-aided semi-passive tracker said sequence of semi-active laser-based images at said first predefined rate;
receiving at said laser-aided semi-passive tracker said sequence of passive ambient-energy images at said second predefined rate;
processing by said laser-aided semi-passive tracker an image pair comprising one of said sequence of semi-active laser-based images received within a predetermined time of one of said sequence of passive ambient-energy images in order to map laser spot coordinates of said laser spot of said one of said sequence of semi-active laser-based images to said one of said sequence of passive ambient-energy images; and
tracking by said laser-aided semi-passive tracker said laser spot coordinates on said sequence of passive ambient-energy images that are not received by said laser-aided semi-passive tracker within said predetermined time of said one of said sequence of said semi-active laser based images.
8. The method of claim 7 wherein said predetermined time comprises less than about 10 milli-seconds.
9. The method of claim 7 further comprising registering using an image registration stage said sequence of active laser-based images with said sequence of passive images.
10. The method of claim 9 wherein said registering comprises frame-to-frame image registration.
11. The method of claim 7 further comprising the step of using said sequence of semi-active laser-based images to designate said target for semi-passive tracking of said target.
12. The method of claim 7 further comprising the step of automatically reverting to a passive-only horning mode if receipt of said laser spot coordinates is discontinued.