US 6,208,286 B1 · Method for discovering the location of a living object and microwave location device for realizing the same

Abstract

The method includes radiating an RF signal within a time Tt, receiving a reflected signal within a fixed time Tr equal in duration to the fixed time Tt of the radiated signal plus a delay τd between the end of the signal radiation and the beginning of the reflected signal reception. Once a modulated component is detected, a level of the component is measured and the reception time of the reflected signal is modified. This is carried out until the level of the modulated component decreases relative to that of the initially reflected RF signal and until the signal stops coming in. A distance is further determined from the reception time of the reflected signal with the modulated component. The method can be implemented using a microwave locator comprising a modulator and a transmitter which includes an oscillator, a power splitter and a transmitting antenna. A receiver comprises a receiving antenna, a microwave receiver, a preamplifier/demodulator and a signal processing unit. The modulator is tunable. The apparatus further includes a first pulse modulator in the transmitter and a second pulse modulator in the microwave receiver. The modulator has a control output which is connected to a control input of the second pulse modulator so that the receiver receives the reflected signal with a delay relative to the end of the signal radiation by the transmitter, and the enable time of the microwave receiver is modified. The signal processing unit measures a level of the modulated component.

Claims16

Dependent claims

A method for locating a living object, including radiating a radio frequency (RF) signal, receiving a reflected RF signal, detecting a component of the received RF signal, wherein the received RF signal has been modulated in amplitude and phase corresponding to a heart rate or breath frequency of a substantially motionless living object, and establishing, on the basis of the detected component, the presence of a living object,

wherein said radiating of an RF signal is provided within a fixed time Tt, said receiving of a reflected RF signal is provided within a fixed time Tr equal in duration to the fixed time Tt of the radiated RF signal plus a delay τd between an end of the RF signal radiation and a beginning of the reflected RF signal reception,
the method further comprising:
measuring, once the modulated component is detected, a level of the modulated component;
modifying the reception time of the reflected RF signal until the level of the modulated component decreases relative to the level of the modulated component in the reflected RF signal received within the fixed time Tt, and up to an end of arrival of the reflected RF signal;
and
determining a distance to a living object location by the following expression:
D≡c(τd+Trr)/2
where c is a velocity of propagation of an RF signal,
τd is a duration of a delay between the end of radiation and the beginning of reception of the RF signal, and
Trr is a time of reception of the reflected RF signal, within which the level of the modulated component level has been decreased, said time corresponding to a period from the beginning of the reflected RF signal reception to the end of the reflected RF signal arrival.

7 more elements

A microwave locator comprising a modulator and a transmitter including an oscillator, a power splitter and a transmitting antenna, all having signal inputs connected in series to signal outputs to radiate an RF signal with modulation, a receiver including a receiving antenna, a microwave receiver, a preamplifier/demodulator and a signal processing unit, all having signal outputs connected in series to signal inputs to receive a reflected RF signal having a component modulated by a living object heart rate or breath, and to extract the component at an output of the preamplifier/demodulator, a second signal output of the power splitter being connected to a control input of the microwave receiver, a first control output of the modulator being connected to the transmitter, and a second and a third outputs of the modulator being connected to a first and a second control inputs of the preamplifier/demodulator, respectively,

wherein said modulator modifies a duration of control pulses and locks them,
said microwave locator further comprising a first pulse modulator in the transmitter and a second pulse modulator in the microwave receiver, a first signal output of the power splitter being connected to an input of the transmitting antenna via a signal input and a signal output of the first pulse modulator, and a second signal output of the power splitter being connected to a control input of the microwave receiver via a signal input and a signal output of a second pulse modulator, a control input of a first pulse modulator being connected to a first control output of the modulator to lock the radiation time of the RF signal, the modulator having a forth control output connected to a control input of the second pulse modulator to receive the reflected RF signal in the receiver with a delay relative to an end of the RF signal radiation by the transmitter and to modify an enable time of the microwave receiver, whereby the signal processing unit measures the modulated component level.

Dependencies are inferred from the claim text.

Method for discovering the location of a living object and microwave location device for realizing the same

Life of this patent

Method for discovering the location of a living object and microwave location device for realizing the same

Life of this patent

Abstract

Claims16