A data processing device and method for detecting interference in a FMCW radar system are described. For each of a plurality of transmitted chirps of the radar system, a high pass filter is applied to a receiver signal of a receiver channel of a radar receiver during an acquisition time corresponding to a transmitted chirp to remove those parts of the receiver signal corresponding to a reflected chirp having a power at the radar receiver greater than the noise power of the radar receiver of the radar system. The receiver signal power is calculated from the high pass filtered receiver signal. The receiver signal power is compared with a threshold noise power based on an estimate of the thermal noise of the radar receiver to determine whether the receiver signal corresponds to an interfered received chirp including interference or a non-interfered received chirp not including interference.