Investigation of spurious emissions from cellular phones and the possible effect on aircraft navigation equipment

The study described in this paper investigated the possible interference of spurious emissions from cellular phones on aircraft navigation and communication equipment. Six wireless phone technologies were investigated over three frequency ranges, which covered the receiving ranges of five aircraft systems. The aircraft systems examined were very-high frequency omnidirectional range (VOR), localizer (LOC), very high frequency communication (VHF), glide slope (GS), and global positioning system (GPS). Research was performed in a semi-anechoic chamber (SAC) and a reverberation chamber (RC), with the phone at a distance of 1 m from the receiving antenna. Two antenna orientations were tested in the SAC. Initial tests yielded the appropriate height from the receiving antenna above the ground plane that would produce a maximum field measurement. Keypad programming was used to simulate worst-case phone transmissions. Radiated power measurements were performed and analyzed taking into consideration path loss results from the RTCA/DO-233 study. None of the six phone technologies investigated exhibited a power level greater than a 38-dBm path loss level above the maximum sensitivity of the aircraft system antennae when tested 1 m away from the antenna. These results indicate that, for the aircraft systems tested (VOR, LOC, VHF, GS, and GPS), the antenna of these systems would not have detected the emissions of the phones used in this study (CDMA-cellular, TDMA-11 Hz, TDMA-50 Hz cellular and PCS, GSM, and DCS-1800).