Types of Tracking Devicesby Milton Kazmeyer
Keeping track of people or valuable items has never been easier, thanks to advancements in communication technology. A tracking device is an electronic unit designed to broadcast its location, either in response to a signal or at set intervals. Tracking devices can allow you to monitor merchandise, locate endangered animals, or help rescue workers find you in an emergency.
Radio frequency identification, or RFID, uses small tags containing a microchip or transistor with encoded information and an antenna for receiving and sending signals. When the tag detects a signal on the proper frequency, it absorbs the energy and uses it to respond with the encoded information. This allows a scanner to identify a tagged item from a few feet away, and is a common form of inventory control. The antishoplifting tags on expensive merchandise are RFID trackers, designed to go off if they come near the scanning bars at the entrance and exit of a retail store.
By adding a power source to a RFID tracker, you can greatly increase the range its signal will travel. These “active” trackers can respond to a wide-band scanning signal, or you can set them to go off periodically for long-term tracking purposes. A common use of this type of tracker is in the field of biology, when scientists tag animals for the purpose of tracking their behaviors or monitoring their health. This type of tracker is easy to implement, but it only provides a directional signal, requiring triangulation and estimation of the signal strength to provide a rough location of the device.
GPS and Satellite Tracking
The advent of the Global Positioning System has led to the development of incredibly accurate tracking devices. A GPS receiver compares signals from a network of satellites overhead to pinpoint its location to within a few meters, providing real-time positional data. Paired with a satellite radio, this can allow a tracking device to report its location anywhere in the world almost instantly, making it a valuable tool in rescue operations. Survival beacons and personal tracking devices often incorporate GPS technology to speed rescue operations, and many cell phones contain GPS trackers to help authorities locate 911 callers in an emergency.
Even if your cell phone is not GPS enabled, it may contain technology designed to help the provider track the device. If you need to call for help in an unfamiliar location, 911 services can contact your provider and identify which cell towers can pick up your phone’s signal. By comparing the signal strength at each of these known locations, they can estimate your phone’s approximate location, which may be enough to direct emergency services to your location. This type of tracking is not as effective in urban environments, however, where signal clutter and echoes from buildings can make it difficult to pinpoint a location to within a few blocks.