Beyond IR’s ability to travel through glass, its accuracy can be impacted by still ubiquitous fluorescent lighting. Certain surfaces and materials may also cause issues. If a material reflects light it can, and often does, reflect IR. So glass partitions and windows can again cause problems, but so can in-room monitors and even some floor surfaces. The need to control light signals in order to overcome those obstacles requires many transmission devices to achieve the desired level of accuracy.

Ultrasound, as a sound-based technology, doesn’t pass through glass (think of recording studio sound booths where the engineer can see the musician, but has to communicate via a PA). So if an ultrasound-based system is giving you the location of the equipment or caregiver you’re looking for within a room, they will actually be in that room – especially since ultrasound’s locating accuracy can be measured in inches. This means that an open-plan hospital design can continue to look as it was first envisioned without having to make accommodations in order to use the RTLS. Ultrasound transmission devices can also create up to four distinct zones per unit, whereas IR-based transmitters can only handle one zone per unit (see figures 1 and 2), requiring a higher number of devices if bay-level accuracy is required.



Depending on your take, the power source for IR or ultrasound will either be a positive or a negative. The lithium batteries used for IR are expensive and they’re rough on the environment, requiring expensive disposal procedures.

By contrast, ultrasound systems can use standard 1.5V D cell batteries, which are more affordable, easier to track down and easier to recycle. Both D cell and lithium batteries do have rechargeable options, but you should confirm with the manufacturer that it’s alright to use rechargeable before you go that route.

Lithium battery-powered IR RTLS also require more units. Due to the number of transmission devices required, an ambulatory recovery room with four bays separated by curtains would require 14 location devices to deliver bay-level accuracy to create zones in order to control light and ensure line-of-sight confirmation. By contrast, ultrasound systems in the same room would require just three units.

Business Affairs Homepage