Next-Generation SAL Pulse Code

The report presented here details a proposal by Gleason Research Associates, Inc. (GRA) for consideration in the SBIR Direct to Phase II (D2P2) AF-233-D017, Next Generation SAL Pulse Code. á Current Semi-Active Laser (SAL) missile systems utilize Pulse Repetition Frequency (PRF) and Pulse Interval Modulation (PIM) for both target designation and terminal homing for SAL engagements.á While PRF designation has been proven in the battlefield environment, PRF designation is susceptible to being spoofed with modern technology. As adversaries increase their sophistication in Countermeasures (CM), this is likely to become a serious problem. PIM designation offers a solution to this problem. However, the current state-of-the-art PIM implementation is limited by several factors.á Primarily, the current sequences are too short and thus, the current family of PIM code sequences will repeat in all but the simplest of engagements.á This allows for an adversary to capture the given PIM code sequence and use this process as an effective CM. As missile capabilities increase in maximum target range, this exacerbates the issue.á There exists fielded missile seekers with correlation algorithms that are too cumbersome and time consuming to handle all but the simplest of PIM code sequences, so much so that the engagement could potentially be over before correlation is achieved and thereby result in a flight failure.á Thus, a more robust correlation algorithm is required.á The new algorithm must almost instantly identify the current pulse index location in the PIM sequence to guarantee a tactically effective, laser spot acquisition. To mitigate these issues, improvements in PIM algorithms, and corresponding implementations, are required that would provide better coordination of non-conflicting laser codes for cooperative engagements. The proposed, new longer PIM sequences shall be utilized so that the specific sequence would not repeat during a long battle engagement, and also not interfere with other neighboring SAL engagements.á A correlation process is also required that is essentially instant for each query of possible consecutive pulses to match the expected time arrival of designator pulses. Many pairings may be required for adjudication in a pulse rich environment.á The current PIM implementation requires a keyword process that is only available at one physical location and could create problems in obtaining the necessary keyword(s) in a timely manner.á De-centralized keyword generation methodologies will be addressed in this effort.