How do RTLS systems work? originally appeared on Quora: the place to gain and share knowledge, empowering people to learn from others and better understand the world.

Answer by Mohammed Smadi, CEO at PenguinIN Inc., on Quora:

There are different types of RTLS systems depending on the type of technology used. In general, there is a locator (a.k.a. gateway or receiver) that “communicates” with a tag. The message communicated between the tag and the locator allow for the calculation and share of the location of the tag.

There are two types of RTLS system, namely: passive and active. In a passive system, the tag has no battery. When it comes in close proximity of the locator (e.g. Passive RFID Exciter), the tag receives enough energy from the exciter causing it to “chirp” back its unique ID. Merely by knowing where the RFID exciter is, we can determine where the tag is. In this case, there is visibility of the tag only at the location AND moment in time when it got excited due to proximity to the exicter. Once it moves beyond that “choke point”, then the visibility is lost and we only can claim “last seen” option for this tag.


The other type of RTLS systems is active. In active systems tags have a radio that is battery operated (E.g. Bluetooth Low Energy, Wi-Fi, Infra-Red, Ultra Sound) and continues to “chirp” or “receiver a chirp” at a determined frequency and transmit power (loudness level). The receivers get these chirps and do some interesting operations on them (e.g. triangulation, angle-of-arrival, time of flight, time difference of flight, …) and estimate the location. This ubiquitous, venue wide visibility is valuable in many use cases BUT comes at the cost of increased tag complexity/power consumption/cost AND requires venue wide deployment of receivers.

Finding the optimal tradeoff between required visibility of tracked objects, cost (tags and receivers), and support is usually a hard exercise that requires different stakeholders including IT/network managers to work with vendor system engineers to work together to specify and build the right design.

Many RTLS Solution vendors offer requirement gather and design services to the clients. PenguinIN – Complete Indoor Tracking and Positioning is always keen at supporting clients with requirement. We are happy to serve and discuss new requirements.

This question originally appeared on Quora – the place to gain and share knowledge, empowering people to learn from others and better understand the world.


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