A Guide to “GPS Trackers” and How They Work

If you’re worried about losing your pets, motorcycle, boats, etc., fear not. Technology companies, like Pod, have several options for devices you can use to keep track of your furry friends and other valuable possessions, such as your keys, wallet, bike – you name it.

Not all trackers are created equal, however, and to use one effectively, it helps to understand how your tracker works, and in what situations it is most effective. You may be surprised to find some “GPS trackers” don’t use GPS at all! This post will break down the four most common tracker technologies (RFID, Bluetooth, GPS, and Wi-Fi), explain how they work, and give the pros and cons of each.

RFID

How it works:
Radio frequency identification (RFID) systems have two components: a reader and a tag. The reader’s job is to request information from the tag using a radio wave and interpret the signal it receives in return. RFID systems utilize several different types of tags, but generally, the tag’s job is to sit quietly until it is pinged by a reader, at which point it transmits back a small amount of information (usually a unique identifier) stored on its chip. The reader processes this information to make sure it’s communicating with the correct tag and can detect its distance from the tag by checking the delay on the return signal. This allows the reader to play a game of “hot and cold” with the tag, guiding you to your lost object.

Pros:
The simplicity of an RFID system gives it a few advantages. For one, all the information processing happens at the reader, so the tags can be incredibly small (possibly shorter than a centimeter) and use almost no energy. Some companies claim their tags last over 10 years without a battery change! RFID trackers are also very accurate and can detect variations in tag distance as small as a couple centimeters. Therefore, these systems are very good at locating objects that get lost in nooks and crannies around the house.

Cons:
RFID tracking systems are short-range, usually around 100 meters, and while this is plenty for finding keys in your house, it is inadequate for long-range tracking. Did your cat wander to the farm, or did he chase a squirrel into town? With RFID, you’re out of luck. Also, you have to keep track of the reader. If you lose the reader, you won’t be able to locate any of your RFID-tagged belongings.

Bluetooth

How it works:
Bluetooth trackers consist of a primary device (usually a smartphone) and a tag, like RFID systems. Bluetooth communications are two-way, though; once the devices are paired, they are able to access the hardware of the other remotely. This means that with a Bluetooth tracker, you can use either the tag or the primary device to find the other. For example, let’s say you’ve lost your keys. You tap a button on your phone which activates a speaker in the tag, and you can “Marco Polo” your way to your keychain. Alternately, if you’ve lost your phone but have your keys, the keychain tag can ring your phone. You can even connect several Bluetooth tags to the same primary device, meaning you can locate your phone with anything that has been tagged.

Pros:
Bluetooth trackers’ ability to communicate both ways between the primary device and tag is their biggest strength, and the system becomes more useful the more tags you use. It’s unusual to lose your keys, wallet, cat, and phone all at the same time. So long as you have one tag, you can locate the primary device, and then use it to locate the others.

Cons:
Because of the two-way nature of Bluetooth, the tags need to be more sophisticated than those in RFID systems, and therefore are larger and use more energy (although they still boast battery lives of around a year). Furthermore, Bluetooth connects over an even shorter distance than RFID, only up to about 30 meters. This is a really short range, especially if you’re hoping to track something mobile like a pet, motorcycle or boat which can move long distances in a short amount of time. Having Bluetooth constantly switched on drains some smartphone batteries in a few hours, particularly Android devices. Finally, some experts warn that using Bluetooth devices may pose a security risk for sensitive data on your phone.

GPS

How it works:
Global positioning system (GPS) trackers are fundamentally different from either RFID or Bluetooth. Instead of a personal device searching for nearby tags, the tag communicates with satellites, requesting its own location on the globe. Several satellites work together to locate the tag, and then send the tag coordinates detailing its position. The tag then uploads those coordinates to a server using a cellular network, where it can be accessed by a personal device, such as a phone or computer.

Pros:
Because they don’t require the tag and a personal device to communicate directly, GPS trackers have unlimited range. Also, they don’t require you to play games of “hot and cold” or “Marco Polo,” because your tag knows it’s geographical location and can point itself out on a map. This makes it a good choice if you’re worried about a pet escaping, a car being stolen, or finding anything that might need to be tracked from a long distance. You can simply look up the tag’s location, as it will be broadcasting and updating in real-time.

Cons:
In some ways, GPS systems are the opposite of RFID; the tag itself has to do all the heavy lifting, driving up the size and significantly reducing battery life. Most of these tags need to be recharged every two or three days. The tag also needs to be able to communicate with satellites; in other words, it needs a mostly unobstructed view of the sky. Tall buildings, bad weather, or just being inside can cut off a GPS signal. Lastly, GPS trackers don’t provide the same accuracy as an RFID device, as GPS satellites usually pinpoint an object’s location within 5-10 meters. The combination of these factors makes GPS trackers less useful for keeping track of your everyday objects. The tags are a little too bulky to keep comfortably on a keychain, and aren’t accurate enough to find the wallet behind the couch.

Wi-Fi

How it works:
Wi-Fi tracking can loosely be thought of as smaller-scale GPS tracking. Instead of using GPS satellites to triangulate a location, these tags use nearby Wi-Fi hotspots. Wi-Fi trackers determine their approximate distance from a hotspot based on signal strength. If the tracker can identify its distance from hotspots in at least three directions, it can figure out its relative location. The hotspots have a geographical location connected to their physical (or MAC) address, so by checking the MAC addresses of the nearby hotspots, the tracker can determine its geographical location to about 5 meters.

Pros:
Wi-Fi trackers, due to their similarity to GPS, share GPS advantages: long range (so long as there are nearby hotspots), and map location. In addition, because the tags use Wi-Fi instead of satellites, they work just fine indoors, in bad weather, or in other sky-obscuring situations where GPS might fail.

Cons:
Wi-Fi trackers also share the reduced accuracy of GPS trackers. Furthermore, Wi-Fi tracking is only useful in heavily urbanized areas with lots of hotspots. If you live somewhere rural, where it’s rare to have overlapping Wi-Fi signals, this method won’t work. Depending on where you live, GPS could be more reliable.

To sum it all up…

So there you have it! If your primary concern is keeping track of things you tend to keep in your house, an RFID device might be right for you. If you don’t want to keep track of an extra controller, or if you’re prone to misplacing your phone, consider Bluetooth. If you need powerful tracking over long distances, look for a tracker with either GPS or Wi-Fi (or both! Due to the nature of the technologies, Wi-Fi and GPS cover the other’s weaknesses pretty well). But, if you need to track something that you really love, then you should definitely consider a tracker that combines as many of these technologies, particularly GPS.