GPS Trackers: How they work
GPS, short for Global Positioning System, uses a constellation of satellites to track and locate a GPS-receiving device, such as a vehicle tracker or smartphone, anywhere on earth.
Brief History
GPS was originally developed specifically for the US military’s use during the Cold War and is comprised of a constellation of around 31 satellites.
On a global scale, a few other countries and entities, such as China, Russia, Japan, India, and the European Union, also have their own version of the GPS, known as the GNSS (Global Navigation Satellite Systems).
Each of these countries has their own names for the satellite constellations, for instance:
- China has one of the largest constellations, comprising 35 satellites with global coverage, known as BeiDou, launched in 2000.
- The European Union has around 30 satellites with global coverage known as Galileo, first launched in 2011.
- Russia has around 24 satellites with global coverage known as GLONASS, first launched circa 1982.
- The Indian Regional Navigation Satellite System (IRNSS) has around 8 satellites with only regional coverage, with an operational name of NaVIC.
- Japan has regional satellite coverage with four satellites known as QZSS (Quasi-Zenith Satellite System).
How it works
Central to the functionality of GPS is time, i.e., the time a signal left the satellite. The GPS receiver then logs the time it receives the signal, and the time difference is computed as a distance.
When triangulated against three of four satellites, the GPS receiver’s location can be estimated with an accuracy of over 90%.
While GPS has global coverage, it doesn’t necessarily mean a GPS-enabled device will automatically work abroad because if the device uses “assisted GPS,” it also has a SIM card to connect to a cellular network, which is regional.
Assisted GPs, or A-GPS devices, rely on more than satellites to map out their coordinates. Cell towers and even Wi-Fi networks send out signals that can be used to triangulate a device’s location. See how triangulation works.
When data from three sources is analyzed together, it’s known as triangulation and helps give an almost precise location of a device.
Assisted GPS helps in situations where there is no direct line of sight between a GPS-enabled device and the satellite 20,000 km away. Physical obstacles like buildings and trees can block satellite signals and make them less effective. This is where cell signals and Wi-Fi come in and fill the gaps.
Of course, some areas are disadvantaged if they have poor cell network or Wi-Fi coverage, and the data in these instances is bound to be less accurate.
—
Apart from keeping an eye on pets, belongings, family members, and vehicles, GPS is also employed in a variety of contexts, including navigating around unfamiliar areas using GPS-enabled devices.
The trackers send signals to a monitoring and tracking center’s dashboard or a smartphone app. These signals can be configured to be sent;
- At pre-determined time intervals
- When requested by the smartphone app
- When sent by the wearer of a wearable device or when an SOS button on a car is pressed
- When a geofence is crossed.
Geofence
A geofence is a virtual fence, i.e., a geographical area demarcated on the map, and when the tracker goes beyond its boundaries, a push notification or text message is sent to a smartphone or monitoring center.
This is useful in a variety of cases, such as for parents with school-going children or law enforcement agents monitoring individuals ordered not to go to or beyond certain areas.
When a signal is sent and received, the tracker’s current location and history are shown on a map and can be viewed either via a smartphone app or web page.
Use cases for GPS and tracking devices
- Vehicle and asset tracking is one of the most common use cases for GPS. GPS vehicle trackers come in many varieties and features that, apart from location tracking, include speed limitation, geofencing, crash detection, remote shutoff, and even audiovisual recording of an event.
- Fleet owners, in particular, are some of the biggest consumers of GPS devices. Business owners and fleet managers use GPS data to track vehicles, monitor mileage, and analyze delivery and transit routes for business decisions like route optimization and costs such as fuel and tolls. This is even used by customer service personnel, who can provide more accurate arrival times for packages or pickups.
- Geofencing with wearable tracking devices for young children can help parents or guardians keep tabs on their children whether they are at school, at home, or at a playground, and some with advanced features can learn a routine and send notifications when a deviation from the norm is detected.
- Tracking devices for pets can help keep a virtual leash on them in case they run off, get lost, or are stolen.
- Medical use cases include having individuals under medical observation wear tracking devices that are geofenced or that would allow them to press the SOS button and notify the monitoring center, caregivers, or relatives in times of distress.
- Personal GPS devices can also help individuals share their location with friends and family or request emergency SOS services. Such individuals can include long-distance drivers, joggers, night shift workers, or those who work in remote or hazardous locations.
- Even simple items like luggage and parcels can be tracked with a simple battery-operated GPS device.
The risks, downsides and dark side of GPS
- Stealth Tracking and Privacy
One of the main concerns individuals might have about GPS is being tracked without their knowledge.
GPS devices are getting smaller, sleeker, and more robust. A magnetized GPS device can be hidden in or on a car, and the unwitting victim can be tracked for days with ease. Even smaller ones can be placed inside luggage and bags and can last for a very long time.
A smart phone itself is a tracking device, and once someone has been able to discreetly install the requisite software, the victim can be tracked indefinitely. More on phone tracking
Even when not being tracked, tracking devices, particularly when connected to unsecure Wi-Fi networks, can be hacked and location data viewed and downloaded. The harvested data, other than a breach of privacy, can be used for other damaging purposes.
- Accuracy
A GPS device can give inaccurate information due to a variety of factors that can be beyond an individual’s control. System glitches can cause the device to relay inaccurate information, inducing panic, e.g., when a child’s location on a map is seen to be on the highway, hours after school has ended.
Poor network coverage, particularly in the cellular network, is one of the major reasons for the malfunctioning of GPS devices. This is particularly rife when the device is being used indoors or in underground basements.
A-GPS (Assisted GPS) devices are better than just plain GPS devices since they can leverage cellular and Wi-Fi networks to calculate location rather than just the GPS satellite, which a lot of times is usually out of line of sight.
- Cost
Maintaining a GPS device is by no means cheap. Subscription charges can be steep, depending on the choice of vendor and especially on the security and operational features inherent or requested.
—
Despite the drawbacks, the popularity of GPS devices in mainstream applications is a clear indication that their usefulness far outweighs their downsides.
—
