GPS | ∙ Device receives satellite signals to calculate wearer's position, then relays it to the appropriate party ∙ Enable virtual boundaries that trigger an alert when crossed ∙ Speed and accuracy can be augmented with Assisted GPS or Bluetooth technology ∙ Examples: GPS Smart Shoe, Tracking System Direct wristwatch, Comfort Zone mobile phone, Keruve wristwatch and receiver, Project Lifesaver Protect, and Locate digital watch and receiver
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Radiofrequency | ∙ Device emits radio waves to a locating antenna ∙ Can be manually activated or used to create a virtual boundary ∙ Radiofrequency identification creates a “tag” to track individuals each time they pass through an area ∙ Examples: Project Lifesaver locating device, LoJack Safety Net
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Cellular triangulation | ∙ Device connects to the network and communicates with cellular towers ∙ Connects with the closest tower to conserve power ∙ Assisted GPS combines cellular and satellite positioning
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