Measuring interference from a UWB transmitter in the GPS L1 band

This paper presents quantitative interference measurements from a commercially available ultra-wide-band (UWB) transmitter in the Global Positioning System (GPS) L1 band (1575.42 MHz) to investigate the possibility of co-locating UWB and GPS radios. Theoretical analysis shows that a single UWB transmitter conforming to the United States Federal Communications Commission (FCC) specifications could degrade the sensitivity of a GPS receiver by three decibels if both radios were separated by a distance of 1.33 meters. In this work, we measure radiation from the transmitting antenna and associated circuitry of a UWB (multi-band orthogonal frequency division multiplexing) based commercial USB device. Our measurements reveal that the circuitry associated with the UWB device is a significant source of interference while the interference due to antenna transmissions is minimal. Therefore, we believe that adequate shielding of UWB circuitry is necessary to allow a UWB transmitter and a GPS receiver to be co-located.