How Small Can A GPS Tracker Be? Well, It Depends…
About once a month we get a phone call from somebody who wants a small GPS tracker. A really, really small one. Like, small enough to be sewn into a child’s clothing. That kind of small. And they would also like to be able to watch the tracker update every second or so, in real time. Oh, and, it can’t cost more than about $10 bucks. Usually this phone call happens right after someone has seen a tracking device in a movie or a cop show. And while each piece of this is technically possible, putting it all into one single package is not, at least not yet.
There are several factors that determine the minimum size of a monitoring device. Let’s look at them one by one:
- Location Tracking Method: These days, there are multiple methods available to hardware designers when they want a device to monitor location. Here are just a few on the most common technologies in use:
- GPS: Over the last 10 years, most of the devices that were used to track location were GPS systems. This is a system of satellites that orbit the earth, providing very precise location information all over the planet. While still the most popular and precise option available, other technologies may be a better option, particularly when the power budget is low, or the device has to provide location services inside a building structure.
- Cell Tower: Some devices have the ability to report their proximity to nearby cellular towers. Since the device has to be relatively close the the cell tower in order to “see” it, this information can be used to get a general idea of where the device is. While not as accurate as GPS, this method of identifying the location of a device requires significantly less power.
- RFID: For most people, the best reference for RFID technology is the toll tag you may have on your car. This tiny device is attached to the windshield, and as the vehicle passes under the toll both, a scanning device “sees” the RFID toll tag and reports the date and time that the tag passed by the toll both. This technology is also used to implant a “chip” into dogs and cats, so that if they are lost a scanning device can be used to read the RFID tag and therefor identify our furry friend. The greatest strength of this technology is that the toll tag or pet implant does not need any type of battery of its own, but the downside is that the tag can only be read when in proximity to a reader.
- Power Source: All tracking devices must have some kind of power supply to two basic things; figure out where they are, and communicate that information when asked to do so. Here are three of the most common power sources:
- Battery: Many devices have an internal battery, which range in size from really small to really large. Batteries can be as small as a grain of rice, but the general rule of thumb is that the smaller the battery, the smaller the amount of power that is available to the device to do what it needs to do.
- Hard Wired: Some devices will be connected to an external power source. This is the most common method for devices that are used to track vehicles over long periods of time. These units may also have a small backup battery in the event that external power is disconnected for short periods of time.
- Radio Waves: One of the reasons that RFID tags can be so small is that they get the power they need to operate from the incoming radio waves of the scanning device. The tag uses this incoming radio wave to charge up a tiny little battery inside the device. It’s not a lot of power, but it can be enough to do the job under the right set of circumstances.
- Communication Method: Once the device has been powered up and a location has been determined, that information has to be transmitted to the owner of the device. Some of the more popular methods are
- Cellular: These days cellular coverage is almost everywhere. Sure, we all find ourselves in situations where cell coverage is not available, but its very rare.
- Satellite: If you find yourself out in the desert, or in the middle of the ocean, chances are good that you won’t have cellular service available. In this case, satellite cellular service may be the way to go. It is very expensive when compared to traditional cellular service, but prices have been coming down over the last few years.
- WiFi: If you are deep inside a large building, cell coverage may be too weak to use or even blocked. In this situation communication over the internet via WiFi may be a good solution.
The smallest device in our portfolio is our SageTracker unit, which uses GPS for location information, and internal battery for power, and cellular service for communication. This allows the device to provide precise location information without an external power source, as well as the ability to transmit this information cheaply and effectively. It’s pretty small, but the main component that defines how small it can be is the battery size. Right now the device can operate for 10-14 days between battery recharges. If we wanted to cut the size of the device in half, we could probably do so, but we would have to cut the battery life half at the same time.
Want to learn more? Do you have an monitoring application in mind that you need help with? Give us a call, we like to help our customers figure out the best mix of technologies needed to solve their problems.