RFID – Short or long range?

Radio Frequency Identification (RFID) has fast become the norm across many industrial sectors from retails to oil and gas. Although this technology has been around for several decades, to many, the potential is only now starting to be fully explored. RFID infrastructure can operate at short or long range, however, its important that the range fits the application. This article will focus on one example of why this is important.

Why Use RFID?

Electronic mustering and personnel on board (POB) within the marine and oil and gas industry is one industry sector which has embraced RFID technology. After all, it is in essence ‘asset tracking’ with the assets being your personnel. Crew, vendors, contractors and visitors all carry a RFID tag, usually in the form of a smart-card. These tags are scanned at key points, usually choke points between different platforms or vessels, allowing monitoring software to record numbers on that location, thus keeping within the safe allowable limit set by the lifesaving appliances (LSA). During an emergency, the same tags are scanned at muster points, effectively counting the personnel present and allowing the identification and last known whereabouts of missing or not mustered personnel.

The most common RFID tags and readers are split into 3 frequency groups:

• Low frequency (LF) 125KHz
• High frequency (HF) 13.56MHz
• Ultra-high frequency (UHF) 865 > 960MHz (dependant of geographical location)

These frequencies are then split into 2 read ranges; short and long range. Short range generally has a read range of up to 100mm (although can be up to 500mm) and usually requires the tag wearer to present their tag to a reader. Long range has a read range between 1m and 10m (although can be more with certain technology tag/readers) and is usually known as ‘hands free’ where the tag is not required to be presented directly to a reader.

The main advantages and disadvantages of each are as follows:

Short Range

There are two main advantages of short range tags, the primary being they have very little susceptibility to interference from the environment since the read range is small and usually requires the tag being presented or swiped at the reader head. The other main advantage, especially when it comes to the human factor, is because the card has to be presented, the chances of missing a tag (or person) is almost eliminated because each acknowledged swipe provides some form of feedback (success or fail) to the tag holder. The main disadvantage of short range tags is the increased time taken to physically present a tag at a reader.

Long Range

The advantage of using long range tags is the ‘hands free’ approach to scanning them. Tags can be read from a distance as they pass a reading head without the need to be physically presented at that reader. This can greatly reduce the amount of time taken to read each tag and multiple tags can be read almost simultaneously. However, the disadvantage of this method is that long range tags can be very susceptible to interference especially from an environment that includes metal or liquids (including human bodies). Thus there is an increased possibility of a tag not being read, especially when you consider the ‘human factor’ of how the tag is being carried or possibly blocked by something being carried on that person.

For example, a UHF smart-card worn directly in contact with the human body such as on a lanyard around the neck reduce the transmission range of the antenna from 10m to 2m and therefore may not be read by the receiving antenna.

EPIC’s Approach to Both Solutions

Because the “EPIC Smart-Trac” POB and mustering system is primarily a safety system designed to look after personnel working in hazardous environments, careful consideration is given to how we use RFID technology so risk is minimised. EPIC insist on the deployment of short range RFID technology during the mustering of personnel for several reasons. Ensuring personnel to present themselves to the muster checker and scan their tag at the reader is particularly helpful during a real emergency as this interaction between tag wearer and reader (or muster checker) can have the extra factor of enforcing reassurance to the tag wearer that a trained person and system has taken control of the situation.

EPIC offer long range scanning of tags for zone control and gangway/bridge movement, but only when the placement of the antennas for the readers can be located in such a manner that the chances of interference from the tag is almost eliminated. Again, for high security areas including access control, EPIC will always recommend the use of a short range scan head to ensure the tag is presented at the reader.