Investigation of Doppler effect in UWB-based rotor-telemetry system

This paper covers a new scenario based on UWB-technique for transmission of data, which is the rotor-telemetry. The rotor-telemetry is a special type of a radio-telemetry, where measuring data of physical parameters like pressure or temperature are captured by sensors predominantly on rotating objects such as shafts or gear parts, transmitted over special on the rotor mounted along-moved antennas and received by static antennas. Most of the typical applications based on the UWB-technique are used on environments, where the channel is time invariant or very slow variant. A new problem appears with this scenario: since the rotor moves fast, the impact of Doppler rises significantly. The consideration of the effect of Doppler in UWB-signals is different than in narrowband signals. In narrowband systems, the Doppler shift is almost equal for all frequencies, so that the compensation is simple by translating the spectrum proportional to the carrier frequency. This assumption is no more fulfilled in UWB-systems, since the low frequencies of the band suffer from less Doppler shift than the upper ones. Not only the radio channel is of importance for the analysis of the Doppler effect but also the geometry of the antenna system has an important impact on understanding the Doppler effect.