A 77-GHz FMCW MIMO radar based on loosely coupled stations

In this work the realization of a frequency-modulated continuous-wave (FMCW) multiple-input multiple-output (MIMO) radar for the 77-GHz frequency band is presented. The proposed system consists of two separate radar units only loosely synchronized by the ramp trigger signal. To realize the separation of each transmitter's signal at reception, as it is required for the MIMO principle, a delayed ramp start of the slave station is implemented leading to different output frequencies for each transmitter. Since the delay caused by the ramp trigger is estimated in each measurement, the required accuracy of the ramp start timing is only defined by the maximum achievable sampling frequency of the used analog-to-digital converter. Due to the derived signal processing algorithms a coherent measurement with the two stations can be realized without requiring an RF link between them.