Some hid badge readers are not broadcasting at the assigned fcc range they are spec'd to broadcast.Thus causing interference with some medical devices and medical infrastructure.Example: rouge signal from hid was causing drop outs on our wireless philips fetal monitors philips rf team conducted a site survey using a radio spectrum analyzer.All references to signal strength refers to measurements.We described the preliminary findings as suggesting that the access control readers seem to be the source for the radiated emi which is causing the issues.Ake (philips) characterized the spectrum breadth of radiated signal to be significantly outside the documentation spec for the readers (the spec frequency is 125khz).Ake focused on the protected 608-614mhz band as it would directly affect the fetal monitoring system.Ake also noted that the radiated signal frequency ran from 300khz (and presumably lower freqs) and reached past 1.3ghz with the same one of two characteristic signatures.Ake noted that the radiated signal affected at least one fcc licensed radio band used for commercial cellular telephony at db levels that would likely interfere with phone service.Ake and i found that nearly all the hid 5535 and hid 5395 readers installed in the areas we surveyed radiated one of two distinct signature patterns of emi above the expected noise floor.The 5535 (keypad reader) showed slightly less signal strength than 5395 (card only readers) readers.Ake described the radiated strength as -90 to -100 db which is 10-20db above the expected level of noise.Each 3db increase equates to a doubling of radiated power.We checked a number of locations to eliminate environmental factors and installation differences.The emi ceased immediately upon disconnecting a radiating reader at the access control panel every time we checked.
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