UHF RFID Versus UHF RTLS

Many companies new to UHF (Ultra High Frequency) RFID (Radio Frequency Identification) confuse it with UHF RTLS (Real Time Location Systems). While both indeed do use UHF RFID, they differ substantially in what they can actually do for you in your business.

Many companies new to UHF (Ultra High Frequency) RFID (Radio Frequency Identification) confuse it with UHF RTLS (Real Time Location Systems). While both indeed do use UHF RFID, they differ substantially in what they can actually do for you in your business.
UHF RFID

Standard UHF RFID systems can see multiple tags on equipment and products up to several meters away, if set up properly. With emphasis on “set up properly.” While UHF RFID works quite well, its unique characteristics require testing in the environment where it will be used to ensure success.

UHF RFID has several purposes:

    • To see if an item has passed a certain point, commonly known as a choke point. Examples of this are items being loaded on or off a trailer at a shipping door or items passing from one area to another in a plant.
    • To verify if something is within a certain area when using a scanning device, such as a handheld reader. If one is scanning shelves of parts or equipment, it will help locate those items.
    • To track usage of equipment in MIS systems.
    • The tags can also have data written to them if needed.

The big thing that UHF RFID cannot do is effectively track the exact location of something at any given time in a cost-effective manner. Generally, UHF RFID uses what are called passive tags for the antennas to read. These tags have no battery and get energized from the antenna signal. If you placed enough antennas all over a facility and enough of these tags, then you could possibly locate something within a certain proximity, but not exactly, and this is hardly cost effective.

UHF Real Time Location Systems (RTLSs)

RTLS, on the other hand, are specifically designed to pinpoint the location of anything with a tag or transponder on it. In fact, RTLS refers to any system that can accurately determine an item or person’s location. An important aspect of RTLS is how frequently assets must be tracked. This data can be used in different ways depending on the application. For example, some RTLS applications only need timestamps when an asset passes through an area, while others require much higher visibility, requiring constant updating of time data.

An ideal RTLS can accurately locate, track, and manage assets, inventory, or people, and help companies make knowledgeable decisions based on collected location data.

Like regular UHF RFID, RTLS can use passive or active tags (tags with batteries), but they use triangulation of multiple antennas to determine the location of an object or person. The strength of the signal at each antenna, combined with the software attached to the antennas, allows the identification of the location of an object or person within less than 1 meter.

The system you choose depends on the needs at your location. They both work quite well when implemented properly by trained professionals.

Also, due to the inherent properties of ultra-high frequencies used in UHF RFID technology and RTLS, you should perform a feasibility study that actually tests the system in the real world environment of the plant prior to implementing these systems in any application.

Back to Basics: The Fundamentals of a Passive RFID System

There has been a lot of talk in the industrial automation about RFID. In past blog posts we’ve discussed topics like RFID ROI and when to use IO-Link RFID. We could talk about things to consider when implementing RFID into your plant or different applications for days. In this entry, though, I’d like to get back to the basics a little bit.

Area of Application for a Passive RFID System:

RFID is used to accurately identify an object on which the tag is placed. In addition to identification, bject-specific information, like maintenance data is contained on the tag.

Typical RFID System
Typical RFID System

How It Works:

Since passive RFID tags contain no battery, the tag is powered up or “woke up” by the RF waves emitted from antenna of the same frequency. Once a tag is located in range it is powered up by the antenna and its memory can be read and transmitted to the processor. The time it takes the reader to extract information from the tag is usually measured in milliseconds.

Three Main Components of a Passive RFID System:


RFID-TagTag
– A combination of a chip and internal coil. The chip is where the data is held in the memory and can contain a few bytes of data or thousands of bytes of data depending on the capacity of the chip.

RFID-AntennaAntenna – Connected to the processor by an external cable or sometimes contained inside the same housing, the antenna transmits the data to and from the tag back through the processor

RFID-Processor Processor – The role of the processor is to organize the data as it is being read or written. The processor is usually connected to a controller, like a PC or PLC, and performs the task issued by the controller.

To learn more about industrial RFID applications and components visit www.balluff.us/rifd.