| 摘要 |
Embodiments of the invention provide apparatus (100) for detecting an erroneous measurement of a range of a target object 20 from a subject object (5) comprising: wireless transmission means (111) for transmitting a signal (111S) having a first frequency from the subject object (5) to the target object (20); detector means (113) for detecting a portion of the signal (113S) reflected from the target object (20) back to the subject object (5); range determination means (131) for determining the range (202) of the target object (20) from the subject object (5) by reference to a time of flight of said portion of the signal (111S), (113S) from the transmission means (111) to the detector means (113); and rate determination means (131) for determining the rate of change of the range (203) by reference to a difference between the first frequency and an apparent frequency of the reflected portion of the signal (113S) detected by the detector means (113), the apparatus (100) being arranged to provide an indication (206) that an erroneous measurement of range has been made if the range (202) determined by the range determination means (131) increases whilst the rate of change of range (203) determined by the rate determination means (131) is negative. |
