TY - CHAP A1 - Liebgott, Florian A1 - Jandt, Marvin A1 - Eberspächer, Mark A. A1 - Liebgott, Annika A1 - Yang, Bin T1 - Spectrum-based online estimation of IQ imbalance for near field radar distance sensors T2 - 29th European Signal Processing Conference (EUSIPCO), Dublin, Irland N2 - A mismatch of the in-phase (I) and quadrature (Q) signal path of a direct-conversion receiver results in IQ imbalance, which distorts the demodulated signal. However, if the imbalance parameters can be estimated, the influence of the IQ imbalance can be compensated. We propose a novel method to estimate the parameters during normal operation of a stepped frequency continuous wave (SFCW) radar distance sensor without the need for a pilot signal. To estimate the imbalance parameters, we exploit the structure of the spectrum of the demodulated signal. Evaluating our method on real sensor data shows superior results especially for very short distances. Y1 - 2021 U6 - https://doi.org/10.23919/EUSIPCO54536.2021.9616359 ER - TY - CHAP A1 - Jandt, Marvin A1 - Eberspächer, Mark A. A1 - Kallfass, Ingmar T1 - Radar imaging based on multiple non-coherent antennas T2 - Proceedings of the SPIE, Florida, USA N2 - A concept for radar imaging based on multiple incoherent millimeter wave antennas is presented. The goal is to use 3D-Imaging, where the object moves along a line and passes a linear array of antennas. To reduce the hardware complexity, a novel radar principle is introduced, which does not require a coupling between TX and RX, but a reference reflector. The RX performs just a RF-power measurement for each frequency step in a SFCW setup. After preprocessing the raw data, any focusing algorithm can be used to obtain the 2D image. Multiple 2D images can be combined to 3D with backprojection. Y1 - 2021 U6 - https://doi.org/10.1117/12.2585568 ER -