An analysis of the effects of RFID tags on narrowband instrument landing systems

The use of RFID tags to identify and track cargo is already common, and expected to grow. Inevitably, many such tags will be used on air freight shipments. Therefore, the effects of such RFID tags on common avionics is an issue of concern to owners, operators, regulators and the traveling public. A recent study by NASA Langley Research Center identified a particular RFID device having a relatively high level of emissions in the 328.6-335.4 MHz band associated with the instrument landing system glide slope function. This paper summarizes a small NASA-supported study performed by the technical staff of the Honeywell Aerospace Advanced Technology organization to estimate the effects of the measured emission levels and signal structure on the Glide Slope guidance function. The paper includes a derivation of the guidance error variance, a model for accommodating RFID duty cycle, and application of the simple analysis recommended by RTCA/DO-294B. The conclusion is that, under likely operating conditions, low duty cycle RFID tags such as the specific family identified by NASA should have no meaningful effect on GS operation. Extrapolations to other narrowband receiver systems reach similar conclusions.