1 Dynamic Scan Scheduling Specification Bruno Dutertre System Design Laboratory SRI International

2 Dynamic Scan Scheduler EW Receiver Signal & Data Processing Schedule Construction Assessment Performance Requirements Detected Pulses Detected Emitters External Parameters Assessment function: determines when rescheduling is required specifies requirements for the new schedule Schedule-construction function: generates a schedule that meets the requirements under real-time constraints Scan Schedule

3 DSS Specification Objective: Determine requirements for the schedule- construction function (on a single platform) Key Issues: Schedule representation Metrics for expressing performance requirements and measuring schedule performance

4 Schedule Representation Strongly periodic schedules: Defined by pairs dwell time/revisit time for each frequency band Feasibility results show that this is too restrictive Pattern-based schedules: Defined by a basic pattern repeated periodically The pattern describes a finite list of successive dwell intervals Pattern Dwell interval

5 Performance Metrics Two emitter types: Search and track radars produce successive illuminations (rotating beams) Missile radars continuously illuminate their target In both cases, detection and tracking require intercepting a minimal number M of pulses in a single dwell Good performance requires a high probability of intercepting M or more pulses in dwell intervals

6 Periodic-Illumination Emitters First Metric: Coverage The probability of intercepting at least M pulses from a single illumination: , m : emitter parameters L, n, A: parameters derived from the schedule pattern This gives an estimate of how well the schedule does at detecting an illumination from an emitter not already detected

7 Extensions of Coverage The previous metric can be generalized to Coverage with respect to successive illuminations (probability of detecting an emitter after a few illuminations) Relative coverage: estimate of how good the schedule is for tracking already detected emitters (uses information about the likely time of occurrence of future illuminations) Probabilistic coverage: to deal with emitters whose characteristics are not known with exactitude, but with some probability distribution All these metrics can be computed from the schedule pattern

8 Metric for Continuous Emitters Requirements for continuous emitters: A good schedule must minimize detection delays Associated metric: Expected delay between the activation of the emitter and the interception of at least M pulses in a single dwell:  : pulse repetition interval of the emitter L, n, : parameters derived from the schedule pattern

9 Global Performance Constraints We can partition emitters in two classes: Emitters already detected (that need to be tracked) Emitters likely to be present (that need to be searched for) This gives three sets of constraints on the scan schedule: Tracking constraints: maximize the relative coverage for each tracked emitter Searching constraints for continuous emitters: minimize the expected detection delay for each probable emitter Searching constraints for periodic emitters: maximize coverage for each probable emitter

10 Conclusion New results: Analysis of scan-schedule performance Metrics for evaluation of pattern-based schedules Requirements for a schedule-construction algorithm Future work: Algorithm development and experimentation Extension to the multi-platform case