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 -