Analysis and design of multifunction radar task schedulers based on queue

Inside the set of systems that constitute the avionics, the radar on board is one of the principal systems, both for the commercial and the military aircraft. For a few years ago, the technologies of electronic exploration arrays are used in the radar design, and specially, in the combat fighters, where the detection and tracking of multiple targets is a fundamental requirement. In this type of environments, it is required to use multifunction radar, MFAR (Multi-Function Array Radar), which joins inside the same system, and simultaneously, so much the classic functions of tracking and surveillance, as all the functions related to the communication, countermeasures, calibration, etc. Thus, the functions are implemented according to specific tasks. The principal ones are: surveillance, tracking, confirmation of false alarm, backscanning, reacquisition and communications plane-missile. Therefore, it is required to work with, specialized subsystems inside the radar. They are called task schedulers. The task scheduler is a key element of the radar, since it does the planning and distribution of energy and time resources to be shared and used by all tasks. This paper analyzes the features of the task schedulers based on tasks queues. Radar time is divided in time intervals that are called scheduling intervals. They allow realizing the task scheduling in a flexible and automatic way, planning individually each interval. Therefore, the task scheduler constitutes, for every scheduling interval, the corresponding queue or queues with the tasks planned to execute in that interval. Then, the tasks that are going to execute are selected from those tasks queues. Therefore, the scheduler includes and applies two scheduling policies: the policy for the constitution of the tasks queues, and the policy of scheduling, which is applied for planning every scheduling interval. Several schedulers have been designed and studied, and it has been made a comparative analysis of different performed schedulers. The tests and experiments have been done by means of system software simulation. Finally a suitable set of radar characteristics has been selected to evaluate the behavior of the task scheduler working.