Location Tracking vs Ranging: How They’re Different & Why it Matters

The growing demand for visibility in operations is giving rise to the use of Real Time Location Systems (RTLS) to reach business goals. Location technology has a wide variety of use cases across industries, particularly in manufacturing, healthcare, and transportation. RTLS uses radio frequency (RF) technology to determine the location of assets in a given space. Organizations attach tags to the assets they want to locate, and these tags transmit location information in that same space. The data collected is connected to software and can then be used to make important decisions about your facility. 

The type of approach you take when deploying your RTLS depends on the overall goal - some need RTLS to ensure safety in their facilities, and others want the increased visibility to make their operations more efficient. Locating (location tracking) and ranging are the two main approaches - but which approach do you need?

What is Location Tracking?

The first approach is locating, also known as near real-time location tracking, which consists of determining the absolute position of tagged objects. A locating approach to RTLS is driven by three main components:  tags, anchors, and a location engine. The tags are attached to what is being tracked (assets or personnel), and their location information gets picked up by the anchors through RF technology.

How Location Tracking Works

The most efficient and accurate mechanism to make this system work is called Time Difference of Arrival (TDoA). Ultra-Wideband (UWB) and Chirp Spread Spectrum (CSS), both of which are RF technologies, can use TDoA to create location information. The tags will transmit signals at regular intervals, called blinks. Since the sent signal is broadcasted, even in an area with multiple anchors and one tag, each anchor in range will receive the blinks from that tag. As no other communication is required back to the tag after that point, this approach works very well for large scale deployments and mass asset tracking. 

Once the signal is received by the anchors in that given space, the anchors timestamp it by its time-of-arrival (ToA) and it is analyzed by the location engine. The location engine calculates the tag’s x, y, z coordinates by analyzing the time differences of arrival of the tag’s blinks between any given anchor pair receiving this same blink. These estimates give indication of the distance from the tag to the anchor, and through multilateration. This data is then sent to the central Indoor Positioning System (IPS) or RTLS.

Use Cases for Location Tracking

Coordinates can be seen visually on a facility map, which allows operators to control what’s happening in their space. There are countless benefits of knowing the near real-time location of assets, from monitoring what’s going in and out of your facility to streamlining operations. For any interaction with the tags, the server needs to communicate back to the tags to warn or inform the user. Hence, typical tracking use cases for process optimization purposes, mustering, evacuation, livestock health, or any industrial application (like warehousing or manufacturing) would be great applications to benefit from RTLS.

When it comes to RF technology, chirp would add a long and reliable range for the indoors and outdoors, while UWB would complement with centimeter accuracy in indoor locations. The ability to track assets has been proven to boost ROI and improve production quality and speed, through the identification of bottlenecks. RTLS data also conveniently integrates with existing IoT (Internet of Things) platforms such as Manufacturing Execution Systems (MES) or Enterprise Resource Planning (ERP).

What is Ranging?

Another approach is two-way ranging, which consists of near real-time relative distance monitoring. In simple terms, ranging determines the distance between two tagged objects. Since the ranging happens between tags, it does not require any infrastructure (such as anchors).

How Ranging Works

The core mechanism used in ranging is called Time-of-Flight (ToF), which requires that the tags have an accurate internal clock. The tags send signals to each other by blinking, and then the tag will record the time that the signal arrives.

The time of flight is then derived from the time of arrival (ToA) and departure (ToD). That travel time can be used to calculate distance based on the speed of light. The location information is then known by both tags involved, and communication to the user of the tag may happen via display, LED, vibrations, or sound. For example, if a tagged truck gets a notification via an alert sound that it is within range with a tagged person, it allows the vehicle operator to slow down before there is any collision.

Use Cases for Ranging

Since tags can be attached to assets, objects, people or vehicles, there are many benefits to two way ranging. One of the key use cases is collision avoidance, as mentioned above, since tags can send alerts if they’re too close to each other. The low cost and ease to create a solution that prevents collisions makes ranging a very compelling solution. Since the range result (distance) does not need to be sent to a server, the potential feedback reaches the user in near real-time.

This enables even the most specific safety applications, such as worker protection in recycling facilities and collision avoidance for vehicle-to-vehicle and vehicle-to-people scenarios. It can even prevent accidents with forklifts, tape-laying systems, shredders, baling presses, and laboratory roller mills. Depending on the required reliability, range, and accuracy, it may be recommended to use chirp, UWB or both RF technologies. Ranging is also useful in creating safety zones or controlling access to certain areas through geofencing. These safety capabilities are the reason that ranging is often used by organizations to meet regulatory compliance requirements.

Key Differences Between Location Tracking & Ranging

There are many differences between locating and ranging, from the core mechanism to the infrastructure required. The main difference is the method of determining the location of the assets.

For tracking there is a whole system of tags communicating with anchors and location engines. But ranging consists of two-way communication between two devices. This is further exemplified through the core mechanisms they use: locating uses TDoA while ranging uses ToF. Different components are needed for each - while locating requires tags to transmit information to infrastructure such as anchors, ranging doesn’t require any infrastructure. 

Because ranging needs constant live monitoring of the distance between two devices, it consumes more air time and energy than locating & TDoA. In addition, since ranging requires more communication, scalability is limited compared to tracking, where there’s no limit to the amount of tags you can add. However, because ranging has less infrastructure and works peer to peer, it has a much faster reaction time which is why it’s useful for safety.

Another key difference is that with locating, you get an exact position of the tag, whereas with ranging, you don’t get a position but a range. Using this range allows personnel to make decisions such as slowing down or braking while in a vehicle, or turning away when getting closer to a prohibited zone. Ranging can also be used in transportation, warehouses, and manufacturing facilities to prevent collisions and meet regulations. This includes controlling access to hazardous or highly secure areas to increase safety. With locating, you can locate the position of important equipment in a hospital, prevent theft in your warehouse, and even find a more optimal route for the vehicles in your facility, among other use cases.

Overview - Key Differences Between Tracking and Ranging

RTLS & Inpixon

Many organizations buy into ranging for regulatory compliance, but eventually want to add tracking to their system to reach their business goals. Inpixon offers the unique ability to do both locating and ranging at the same time, with the same technology. This allows our customers to begin with ranging and later expand their solutions to add anchors that enable tracking.

Want to learn more about RTLS? Watch our webinar on the top challenges organizations face when deploying an RTLS and how to avoid them.