A method for sensing occupancy status within an automotive vehicle uses a
radar sensor system, the
radar sensor system comprising an antenna
system, at least one sensor (10) and
processing circuitry (18). The method comprises illuminating, using the antenna
system, at least one occupiable position within the vehicle with
continuous wave (CW signals), the CW signals being frequency modulated in time. At least one sensor
signal (a) reflected as a result of the CW signals, is received using at least one sensor (10) the at least one sensor (10) defining a plurality of receive channels (1 . . . i), each channel having a different frequency (f1 . . . fi).
Processing circuitry (18) is operable for applying, for each receive channel (1 . . . i), DC offset removal to the corresponding sensor
signal (a) to generate a modified
signal (b); and generating, based on the modified signals (b) one or more occupancy status signals (34, 38), the occupancy status signal indicating a property related to said at least one occupiable position. A
system for carrying out the method is also disclosed. The techniques provide for in-vehicle occupant detection and classification (
airbag suppression), for passenger presence detection and passenger's
vital sign monitoring and for seat-belt reminder functionality (SBR). The
radar system may consist of one or two (or four) outputs (I / Q) per channel. The received signal may be mixed down with a single channel demodulator or an I / Q demodulator into the
baseband. An advanced
signal processing including an
auto calibration routine and
clutter removal may be used to detect occupants and their vital sign (
breathing and
heart beat) and to determine their distance to the radar system.