Abstract: A multiple-input multiple-output (MIMO) radar system, including: a plurality of transmit channels configured to sequentially transmit signals with transmit-channel-designated Doppler division multiplexing (DDM) modulations; and processing circuitry configured to: determine, for each of the transmit channels, an impulse response of phase modulation errors due to DDM coupling of the respective transmit channel from each of the other transmit channels; and generate, based on the impulse response, a reconstruction matrix of modulation DDM coupling factors.

Abstract: A method of detecting leakage, comprising the steps of: performing a sequence of monitoring operations; and providing, when it is determined that leakage is present, a signal indicative of detected leakage. Each monitoring operation includes the steps of: generating a transmit signal exhibiting a time-varying frequency; receiving a reflection signal resulting from reflection of the transmit signal at the surface; forming an intermediate frequency signal for the present monitoring operation based on the transmit signal and the reflection signal; determining a phase of the intermediate frequency signal for the present monitoring operation; determining, based on the phase for the present monitoring operation and the phase associated with at least one previous monitoring operation, a measure indicative of a present rate of change of the phase; comparing the measure with a predefined threshold value; and determining a presence of leakage based on the comparison.

Abstract: A contactless switch device including a reflected signal acquisition unit that acquires a reflected signal of a Doppler radar or a distance measurement radar, an approach and recede detection unit that detects an approach and a recede of a target based on the reflected signal, a target identification unit that identifies the target as a hand waving left and right, up and down, or back and forth, or a thing other than the hand based on a repeated pattern of the approach and the recede of the target, and a switch control unit that executes on-and-off controls on a switch-controlled object based on whether the target is the hand waving left and right, up and down, or back and forth, or the thing other than the hand.

Abstract: A non-transitory computer-readable storage device stores machine instructions which, when executed by a processor, cause the processor to determine a chirp period Tc for radar chirps in a radar frame. The chirp period Tc comprises a rising period Trise and a falling period Tfall. The processor determines, for each radar chirp in the radar frame, a corresponding randomized frequency characteristic during Tfall, and causes a radar sensor circuit to generate the radar chirps in the radar frame based on Tc, Trise, Tfall, and the corresponding randomized frequency characteristics. In some implementations, the machine instructions to determine the corresponding randomized frequency characteristic comprise machine instructions to determine a frequency step having a frequency f_step and a period Tstep. At least one of the frequency f_step and the period Tstep is dithered across radar chirps in the radar frame.