Using a potential combination of RFID and/or ultra-wide band (UWB) technologies, US Patent #,7671,802 provides a method for tracking the on-field locations of athletes and sports equipment (including fast-moving and rapid direction-changing items such as hockey pucks) in real-time.
Distinguishing itself from former like-minded applications, the key to the success of the patent — appropriately titled Active Player Tracking — is redundancy and fault tolerance. For example, instead of an athlete having just one RFID chip embedded in his/her helmet, shirt or other part of the uniform, there would be two or more chips to help identify the athlete in multiple locations so that in the event of something such as transmission blockage, the alternate chip(s) will be able to broadcast the athlete’s or sports device’s location. In addition, the patent calls for enough receivers to cover the field so that an athlete can be tracked by three of them at any time to triangulate their position, but that there should be more receivers than necessary, each one being able to be manually addressed to be activated/de-activated as needed, for fault tolerance.
You can view the patent here.