Method and system for presence detection

• US 7,907,082 B2
• Filed: 10/17/2008
• Issued: 03/15/2011
• Est. Priority Date: 10/19/2007
• Status: Active Grant

• Current Assignee: Volvo Car Corporation (AB Volvo)
• Original Assignee: Volvo Car Corporation (AB Volvo)
• Inventors: Svedoff, Göran, Antonsson, Anders
• Primary Examiner(s): Tarcza; Thomas H
• Assistant Examiner(s): Bythrow; Peter
• Application Number:
  US12/253,494
• Publication Number:
  US 20090167590A1
• Time in Patent Office: 879 Days
• Field of Search: 342/27, 342/28, 342 70- 73, 342 82-103, 342/134, 342/137
• US Class Current: 342/27
• CPC Class Codes: G01S 13/14 wherein a voltage or current pulse is initiated and terminated in accordance respectively with the pulse transmission and echo reception
• CPC Class Codes: G01S 13/18 wherein range gates are used
• CPC Class Codes: G01S 13/56 for presence detection presence detection using near field arrangements G01V3/00, e.g. G01V3/08, G01V3/12; burglar, theft or intruder alarms with electrical actuation G08B13/22 - G08B13/26
• CPC Class Codes: G01S 7/282 Transmitters
• CPC Class Codes: G01S 7/285 Receivers
• CPC Class Codes: G01S 7/2921 based on data belonging to one radar period

Abstract

A method and system for presence detection within a detection volume delimited by an inner radius and an outer radius using microwave radiation. The outer radius of the detection volume is controlled by selecting the length of a first pulse controlling the transmit interval of a microwave transmitter and by selecting the length of a third pulse controlling the receive interval of a microwave receiver. The inner radius of the detection volume is controlled through selecting the length of a second pulse defining a predetermined time period between the first pulse and the third pulse.

Claims

1. A system for presence control within a detection volume delimited by an inner radius and an outer radius from a center of said detection volume, said system comprising:

a microwave transmitter for transmitting microwaves from said center of said detection volume;

a microwave receiver for detecting microwave radiation reflected towards said center of said detection volume;

a first pulse generator generating a sequence of first pulses triggering the microwave transmitter, each first pulse having a length establishing a transmit interval of said microwave transmitter;

a second pulse generator receiving the sequence of first pulses and triggered by a trailing edge of each first pulse to generate a sequence of second pulses, each of the second pulses immediately following and non-concurrent with the respective preceding first pulse; and

a third pulse generator receiving the sequence of second pulses and triggered by a trailing edge of each second pulse to generate a sequence of third pulses triggering the microwave receiver and having a length to establish a receive interval thereof, each third pulse immediately following and non-concurrent with the respective preceding second pulse, whereby each second pulse has a length defining a time period pause between each first pulse and each respective following third pulse, and wherein the second pulse length added to the third pulse length is equal to a transmitter off-time separating the first pulses.

2. A method for presence detection within a detection volume delimited by an inner radius and an outer radius from a center of the detection volume, the method comprising:

providing a microwave transmitter for transmitting microwaves from the center of the detection volume;

providing a microwave receiver for detecting microwave radiation reflected towards the center of the detection volume;

operating a first pulse generator to generate a sequence of first pulses triggering the microwave transmitter to transmit, each first pulse having a length establishing a transmit interval of said microwave transmitter;

operating a second pulse generator to receive the sequence of first pulses and generate a sequence of second pulses when triggered by a trailing edge of each first pulse, each of the second pulses immediately following and non-concurrent with the respective preceding first pulse;

operating a third pulse generator to receive the sequence of second pulses and generate a sequence of third pulses when triggered by a trailing edge of each second pulse, each third pulse triggering the microwave receiver to receive and having a length to establish a receive interval thereof, each third pulse immediately following and non-concurrent with the respective preceding second pulse, whereby each second pulse has a length defining a time period pause between each first pulse and each respective following third pulse, and wherein the second pulse length added to the third pulse length is equal to a transmitter off-time separating the first pulses; and

determining the presence of a moving object within the detection volume based on properties of the microwave radiation being received by the microwave receiver.

3. The method according to claim 2 wherein the step of determining the presence of a moving object within the detection volume comprises using a Doppler motion sensor process.

4. The method according to claim 3 wherein it comprises:

controlling the length of said first pulses by means of a first pulse length detector; and

controlling the length of said third pulses by means of a third pulse length detector.

5. The method according to claim 4 wherein it comprises:

providing a measurement by said first pulse length detector which is fed to a first comparator which is controlled with a first target pulse length; and

providing a measurement by said third pulse length detector which is fed to a third comparator which is controlled with a third target pulse length.