FDA Reissues Interference Warning in 460-470 MHz Frequency Band
Now that the December 31, 2005 deadline has been met, the FDA is reminding again hospitals that they should stop using the 460-470 MHz frequency band because of likely electromagnetic interference (EMI) with mobile radio transmitters (Private Land Mobile Radio Service or PLMRS) licensed to operate in that band of the spectrum. This change was delayed to give enough time to medical facilities but the restriction was finally lifted.
Some hospitals have yet to adapt (though they have been told repeatedly for the past five years), which according to the FCC’s test could put patients at risk because of interference with patient monitoring and alerting systems. Hospitals should use Wireless Medical Telemetry Service (WMTS), a radio spectrum slice dedicated to them by the FCC in 2000. Medical telemetry still operating in the same ranges as some TV channels (174-216 MHz, 470 -608 MHz and 614-668 MHz) are even more at risk because of more powerful broadcasts ordered to Digital TV (DTV) broadcasters by the FCC in the top 100 markets by July 2005, and everywhere else by next July.
Facilities still operating in the frequencies at risk should check with their vendors whether their equipment can be retuned within the WMTS band. If an upgrade is necessary, they might want to evaluate how many channels of telemetry they are likely to need in the future, as some equipment use frequency hopping or other techniques to accommodate many more channels within the same bandwidth (internal interference can be an issue too). The external interference threat is real and has been witnessed in the field as early as 1998.
January 5, 2006 Related topics: Quality, Safety, Errors