RF Interference: Going High, Going Low

This post is the second in a four-part series about radiofrequency (RF) interference and its impacts on wireless solutions such as infant protection. (If you missed the first post, be sure to go back and learn what your hospital has in common with a school bus of kindergarteners!) For this post, I’m going to take a closer look at some of the more technical aspects of RF interference—specifically, what causes it within a hospital.

One mission, two frequencies

Patient security solutions use wireless technology—and different radio frequencies—to perform two essential tasks:

  • Sending messages from the patient tag: patient security solutions use high frequencies for tag transmissions because these frequencies perform well in environments with many other wireless devices.
  • Detecting when a tag is near a monitored exit: solutions use low frequencies to define an area around exits, so the system can detect when a tag is at that particular exit and no other. It is ideal for this task because it can be shaped into a well-defined field that will not cause the tag to be detected too far from the exit or in an adjacent room.

Like all types of radio frequency transmissions, high frequency and low frequency RF signals have potential for interference.

  • In some cases, high frequency noise may affect the transmission or reception of messages from tags. As a result, the system doesn’t receive or can’t properly interpret the message. Interference can be generated by intentional transmitters like paging and other communication systems, as well as by a wide range of equipment that emits noise as a byproduct of its operation. Examples include electric and electronic equipment, wiring and lighting.
  • Sometimes low frequency noise may affect radio signal propagation at the exit (depending on the system design and environment). Though similar in nature to high frequency noise, it’s more localized, typically within a few feet or inches. Sources of low frequency noise include computer monitors, tablet or smart phone displays, ballasts from fluorescent lights and electric motors..
  • Physical barriers—such as wire mesh, foil-backed ceiling tiles, heating and ventilation ducts, and other metal barriers in walls and ceilings—can interfere with high frequency and low frequency signals. Interference may also occur with large metal carts.

Those are the realities of potential interference at both high and low frequencies. How can you address the causes and mitigate the impacts? That’s what I’ll cover in my next post. Stay tuned and use Comments to share your thoughts.