  In multiple-input and multiple-output (MIMO) radar systems based on
Doppler-division multiplexing (DDM), phase shifters are employed in the
transmit paths and require calibration strategies to maintain optimal
performance all along the radar system's life cycle. In this paper, we propose
a novel family of DDM codes that enable an online calibration of the phase
shifters that scale realistically to any number of simultaneously activated
transmit (Tx)-channels during the calibration frames. To achieve this goal we
employ the previously developed odd-DDM (ODDM) sequences to design calibration
DDM codes with reduced inter-Tx leakage. The proposed calibration sequence is
applied to an automotive radar data set modulated with erroneous phase
shifters.
