Communications: directive radio wave systems and devices (e.g. – Testing or calibrating of radar system – By monitoring
Utility Patent
1997-04-16
2001-01-02
Sotomayor, John B. (Department: 3642)
Communications: directive radio wave systems and devices (e.g.,
Testing or calibrating of radar system
By monitoring
C342S028000
Utility Patent
active
06169512
ABSTRACT:
This invention relates to object detecting apparatus and particularly to intruder detection systems which provide imaging of a detection area. In addition, the invention relates to a method of calibrating such a detecting apparatus.
The use of radar is well known for detecting the position, and optionally the velocity, of objects within the range of the radar apparatus. It has been proposed to use radar for detecting the presence or motion of intruders in a defined area, for example so as to provide an alarm system.
If a radar imaging system is to be used for surveillance of an area including obstacles such as are found in a house or garden, the sensitivity of the system for certain areas will be greatly reduced by the presence of these obstacles. One possible solution to this problem is to select a transmission intensity which is such that all points within the detection area have a required minimum sensitivity, to enable intruder detection. A problem with this approach is that the signal intensity will be unnecessarily high in areas which are free of obstacles. One possible consequence of this is interference with systems operating outside the detection area.
Directional antennas are known for transmitting electromagnetic waves substantially in a predetermined direction.
According to the present invention, there is provided a method of calibrating an object detecting apparatus, the apparatus comprising imaging means having a transmitter for transmitting a signal wave substantially in a predetermined direction, and a receiver for receiving a reflected signal substantially from the predetermined direction, means being provided for altering the predetermined direction, the method comprising the steps of:
imaging a detection area having a boundary by transmitting signal waves in a plurality of directions and analysing the received reflected signal waves;
positioning signal wave reflector means of known reflection response at a plurality of positions around the boundary of the detection area;
imaging the detection area with the signal wave reflector means positioned, by transmitting signal waves in the plurality of directions and analysing the received reflected signal waves;
processing the detected images in order to obtain information concerning a boundary parameter of the imaging means at the boundary; and
calibrating a transmission parameter of the transmitter for each direction so as to obtain a desired value of the boundary parameter at a part of the boundary corresponding to the respective direction.
The invention enables calibration of a detection apparatus which incorporates a directional antenna and which enables modification of a transmission parameter for different directions. The calibration method enables the transmission parameter to be adjusted according to the direction of the antenna so as to obtain desired boundary parameters.
The boundary parameter may be the sensitivity of the imaging means at the boundary. This enables detection of an object to be assured at any point within the detection area. This sensitivity is preferably obtained by subtracting the image of the detection area without the signal wave reflectors from the image of the detection area with the signal wave reflector means.
The boundary parameter may alternatively comprise the signal intensity at the boundary of the detection area. In this case, because the reflection provided by the signal wave reflectors is known, and because the attenuation of the reflected signal between the reflector and the receiver is equivalent to the attenuation of the original transmitted signal between the transmitter and the reflector, it is possible to calculate the signal intensity at the boundary from an analysis of the reflected signal.
A knowledge of the boundary signal intensity enables the transmission parameter to be calibrated so that the signal intensity outside the boundary does not exceed a predetermined threshold.
The transmission parameter may comprise the transmitted signal intensity, and this intensity may then be calibrated for each transmission direction.
The calibration may take into account both the signal intensity at the boundary and the sensitivity, so that a maximum signal intensity is provided at the boundary and, where this maximum intensity permits, a minimum sensitivity is also obtained. Where these two requirements are incompatible, the transmission parameter may additionally or alternatively comprise the transmission time in the predetermined direction, namely the dwell time of the transmitter in the respective direction. Increasing the dwell time has the effect of increasing the signal to noise ratio of the imaging means for target detection at the boundary, which results in improved sensitivity, without increasing the transmission intensity.
The signal wave is preferably an electromagnetic wave in the microwave region.
The invention also provides an object detecting apparatus for imaging a detection area having a boundary by transmitting signal waves and analysing the received reflected signal waves, comprising:
imaging means having a transmitter for transmitting a signal wave substantially in a predetermined direction;
a receiver for receiving a reflected signal from substantially the predetermined direction;
means for altering the predetermined direction; and
means for altering a transmission parameter of the transmitter for each predetermined direction, the transmission parameter being selected for each predetermined direction such that the detection sensitivity of the apparatus at the boundary is greater than a predetermined sensitivity threshold, and the signal intensity at the boundary is below a predetermined intensity threshold.
In the apparatus of the invention, the boundary sensitivity for the majority of the boundary is preferably constant and is above a minimum level, so that detection within the boundary is ensured. In addition, the signal intensity at the boundary is limited.
The invention also provides a kit of parts comprising:
an object detecting apparatus comprising:
imaging means having a transmitter for transmitting a signal wave substantially in a predetermined direction;
a receiver for receiving a reflected signal from substantially the predetermined direction;
means for altering the predetermined direction; and
means for altering a transmission parameter of the transmitter for each predetermined direction; and
calibrating apparatus comprising:
means for processing first and second image signals of the object detecting apparatus to analyse differences between the first and second image signals; and
signal wave reflector means having known reflective response, the means for processing first and second image signals including data concerning the reflective response of the signal wave reflector means.
This kit of parts provides an appropriate detection system and enables calibration according to the method of the invention.
REFERENCES:
patent: 3573826 (1971-04-01), Fredericks et al.
patent: 3623107 (1971-11-01), Holdren, III
patent: 4283725 (1981-08-01), Chisholm
patent: 4686534 (1987-08-01), Eddy
patent: 5134413 (1992-07-01), Bruder
patent: 5140331 (1992-08-01), Aulenbacher et al.
patent: 5164734 (1992-11-01), Fredericks et al.
patent: 5204682 (1993-04-01), Beasley
patent: 5264855 (1993-11-01), Lammers et al.
patent: 5294935 (1994-03-01), Bauerle
patent: 5311191 (1994-05-01), Scannapieco
patent: 5313210 (1994-05-01), Gail
patent: 5345243 (1994-09-01), Levis
patent: 5495254 (1996-02-01), Uemura et al.
Barschall Anne E.
Sotomayor John B.
U.S. Philips Corporation
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