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Tactical Engagement Simulation System (TESS) Improved Laser Encoding and Decoding

Description:

OBJECTIVE: Research, develop and demonstrate prototype techniques to increase the laser link reliability and data transfer capabilities of Tactical Engagement Simulation System (TESS) lasers. DESCRIPTION: The Army Multiple Integrated Laser Engagement Simulation (MILES) systems transmit a limited amount of data that is insufficient to provide"reasonably accurate"casualty assessment algorithms on par with constructive simulations. The Army Test Community requires more engagement data than can be conveyed using the MILES laser encoding standard and has supplemented MILES data with Radio Frequency (RF) messages. Army Testers desire to off-load this information from the radio network to the laser beam for line-of-sight direct fire engagements, thus freeing up bandwidth on the RF data network to support more complex engagement types, status monitoring and data collection. A more reliable laser data transfer over the laser link with increased data content and range is also needed for future live training improvements. Modern Digital Signal Processing (DSP) techniques are capable of providing improved detectability compared to encoding used in MILES lasers. For a given laser link DSP using modern error correction techniques can provide improved engagement data reliability and range capability with laser eye-safety constraints suitable for Army training and testing. DSP techniques in laser detection should enhance the data throughput capability on the laser beam. The question to be studied is whether the use of DSP techniques in the laser encoding and decoding would provide sufficient data throughput capability to transmit all data required to initiate a direct fire engagement over the laser beam in a practical, reliable, and cost effective system, and thus obviate the use of the RF network messages for enhanced direct fire TESS. The objectives are to improve TESS laser: Reliability with greatly improved engagement pairing rates. Fidelity supporting expanded weapon types and munitions. Fidelity supporting range-dependent engagement algorithms and probabilities for engagement assessment, and perhaps include use of additional significant factors. Direct fire pairing range with eye-safe lasers allowing modern longer range weapons to be adequately simulated. Time-critical engagement demands on supporting radio networks. PHASE I: Investigate modern encoding, error-correction methods and digital signal processing techniques to improve the laser pairing reliability and enable transfer of an expanded set of engagement parameters from the attacker to the target in a broad range of likely atmospheric conditions. Develop a preliminary design concept to increase the laser link reliability and data transfer capabilities of TESS lasers. The objective is to reliably transfer 150 bits or more of information from the attacker to the target over the laser link for each firing event. Conduct trade-off analysis for system performance, weight, and cost. The deliverable is a report describing the design concept and results of the trade-off analysis. PHASE II: Develop and demonstrate prototype techniques to increase the laser-link reliability and data transfer capabilities of TESS lasers. Demonstrate the prototype techniques in a laboratory environment. After suitable performance is achieved in the laboratory, develop and demonstrate a prototype system in a relevant field environment with the appropriate use conditions and limitations range of transmission, atmospheric scintillation, short transient dwell times on target, and reliable insertion and transfer of variable parameters that can be extracted and used immediately. Demonstration will be at TRL 6. Propose changes to the Government owned MILES Communication Standard. The deliverable, in addition to the demonstrations, is a report describing the technology, designs, demonstration results, proposed changes to the MILES Communications Standard, and conclusions. PHASE III: Transition technology to the Army - Tactical Engagement Simulation System (A-TESS) program of record (POR) using lasers and detectors suitable for incorporation into production ready products. Commercial use of technology is suitable for applications that require robust and reliable covert point-to-point communications links, minimal infrastructure (no wires, cables, or large antenna) and low probability of intercept. Deliverables may include reports, designs, A-TESS lasers, and/or an updated MILES Communications Standard. REFERENCES: 1. Binary Phase Shift Keying (BPSK) Subcarrier Intensity Modulated Free-Space Optical Communications in Atmospheric Turbulence, Wasiu O. Popoola and Zabih Ghassemlooy, Journal of Lightwave Technology, Vol. 27, Issue 8, pp. 967-973 (2009) 2. Free-space optical communications link budget estimation, Larry B. Stotts, Paul Kolodzy, Alan Pike, Buzz Graves, Dave Dougherty, and Jeff Douglass, Applied Optics, Vol. 49, Issue 28, pp. 5333-5343 (2010) 3. Live Player Area Network Standard, PRF-PT-00549, available on the Live Training Transformation portal (https://www.lt2portal.org/). 4. Performance analysis of coherent wireless optical communications with atmospheric turbulence, Mingbo Niu, Xuegui Song, Julian Cheng, and Jonathan F. Holzman, Optics Express, Vol. 20, Issue 6, pp. 6515-6520 (2012) 5. PMT 90-S002M, MILES Communication Code Standards. (http://www.peostri.army.mil/PRODUCTS/MCC/ECP_FILES/MCC_Standard_PMT_90-S002M-8Feb2011.pdf) 6. R. Tyson,"Bit-error rate for free-space adaptive optics laser communications,"Journal of the Optics Society of America, Volume A 19, 753-758 (2002).
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