Microwave sensor with adjustable sampling frequency based on environmental conditions

A Doppler effect intrusion alarm apparatus operating at a first sampling frequency and a second higher sampling frequency to detect intruders comprising:

• transmitter means of said apparatus for transmitting energy into a protected area;
• receiver means of said apparatus for receiving energy reflected from said protected area initially at said first sampling frequency and for transforming said received energy into a motion detection signal which is proportional to any Doppler energy received by said receiver means;
• processing means responsive to said motion detection signal and operative to automatically increase said first sampling frequency to said second higher sampling frequency when said motion detection signal exceeds a predetermined threshold value;
• and
• alarm generating means coupled to said processing means activated when said motion detection signal exceeds said predetermined threshold value and said apparatus is operating at said second higher sampling frequency.

A method of detecting an intruder in a protected area utilizing a Doppler effect apparatus operable to detect intruders at a plurality of sampling frequencies and comprising the steps of:

• transmitting energy from said apparatus into said protected area;
• receiving energy at said apparatus reflected from said protected area;
• developing a motion detection signal which is proportional to any Doppler energy in said received energy;
• automatically modifying said sampling frequency when said motion detection signal exceeds a predetermined threshold value and said apparatus has not been operated at each of said plurality of sampling frequencies;
• and
• activating an alarm generating means when said motion detection signal exceeds said predetermined threshold value and said apparatus has been operated at each of said plurality of sampling frequencies.

A method of detecting an intruder in a protected area utilizing a Doppler effect apparatus operable to detect intruders at a first sampling frequency and a second higher sampling frequency comprising the steps of:

• transmitting energy from said apparatus into said protected area;
• receiving energy at said apparatus reflected from said protected area initially at said first sampling frequency;
• developing a motion detection signal which is proportional to any Doppler energy in said receiver energy;
• automatically increasing said first sampling frequency to said second higher sampling frequency when said motion detection signal exceeds a predetermined threshold value;
• and
• activating an alarm generating means when said motion detection signal exceeds said predetermined threshold value and said apparatus is operating at said second higher sampling frequency.

A dual technology intruder detection system for monitoring a protected area including a first intruder detection sub-system of the type utilizing Doppler effect technology for issuing a first activation signal upon detection of an intruder and a second intruder detection sub-system capable for issuing a second activation signal upon detection of an intruder, such system comprising:

• transmitter means associated with said first sub-system for transmitting energy into said protected area;
• receiving means associated with said first sub-system for receiving energy reflected from said protected area at an initial sampling frequency and for transforming said received energy into a motion detection signal which is proportional to any Doppler energy received by said receiver means;
• comparing means for comparing said motion detection signal with a predetermined threshold value for generating said first activation signal when said motion detection signal exceeds said predetermined threshold value;
• processing means coupled to said first and second sub-systems operative to automatically modify said initial sampling frequency upon receipt of said first activation signal and the absence of said second activation signal from said second sub-system;
• and
• alarm generating means coupled to said processing means activated upon the presence of first activation and second activation signal.