Method and system for presence detection

摘要

The present invention relates to a method and system for presence detection within a spherical detection volume (4), delimited by an inner radius and an outer radius from a centre of the spherical detection volume (4), using an arrangement (2) for transmitting and receiving microwave radiation. The outer radius of the spherical detection volume (4) is controlled through selecting the width of a first pulse (19) for controlling a microwave transmitter (6) to transmit microwaves and through selecting the width of a further pulse (21) for controlling a microwave receiver (15) to detect microwave radiation reflected towards the centre of the spherical detection volume (4). The inner radius of the spherical detection volume (4) is controlled through selecting the width of a pulse (20) for defining a predetermined time period (L T2 ) pause between the first pulse (19) and the further pulse (21).