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

• US 6,208,286 B1
• Filed: 11/05/1999
• Issued: 03/27/2001
• Est. Priority Date: 05/06/1997
• Status: Expired due to Fees

• Current Assignee: Life Sensor Co., Ltd.
• Original Assignee: Ikramov Gairat Saidkhakimovich, Osipov Viktor Rostislavovich
• Inventors: Saidkhakimovich, Ikramov Gairat, Rostislavovich, Osipov Viktor
• Primary Examiner(s): Gregory, Bernarr E.
• Application Number:
  US09/434,675
• Time in Patent Office: 508 Days
• Field of Search: 342/22, 342/27, 342/28, 342/89, 342/175, 342/192, 342/193-196, 342/61, 342/118, 342/127-145, 600/453, 340/522, 340/573.1, 340/573.4
• US Class Current: 342/135
• CPC Class Codes: A61B 5/0507 using microwaves or terahertz waves
• CPC Class Codes: G01S 13/04 Systems determining presence of a target based on relative movement of target G01S13/56
• CPC Class Codes: G01S 13/103 particularities of the measurement of the distance G01S13/12, G01S13/14, G01S13/16, G01S13/18 and G01S13/20 take precedence
• CPC Class Codes: G01S 13/12 wherein the pulse-recurrence frequency is varied to provide a desired time relationship between the transmission of a pulse and the receipt of the echo of a preceding pulse

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 τ_d 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.

Claims

1. 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 τ

_d 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;

2. A method as set forth in claim 1, wherein when the modulated component is detected, the reflected RF signal reception time is reduced in equal intervals.

3. A method as set forth in claim 1, wherein when the modulated component is detected, the reflected RF signal reception time is modified using a successive approximation technique.

4. A method as set forth in claim 1, wherein the RF signal is radiated at a frequency determined as

5. 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.

6. A microwave locator as set forth in claim 5, wherein said microwave receiver uses two-channel quadrature phase detection.

7. A microwave locator as set forth in claim 6, wherein said microwave receiver comprises a first and second phase detector, a quadrature power halving unit, an in-phase power halving unit having a signal input connected to an output of the receiving antenna, a first output connected to a first input of the first phase detector, and a second output connected to a first input of the second phase detector, an output of the second pulse modulator is connected to an input of the quadrature halving unit, said input being the control input of the microwave receiver, a first output of the quadrature halving unit is connected to a second input of the first phase detector, and a second output thereof is connected to a second input of the second phase detector.

8. A microwave locator as set forth in claim 7, wherein said microwave receiver further includes a high-frequency amplifier, a signal input of the in-phase halving unit being connected to an output of the receiving antenna via the high-frequency amplifier.

9. A microwave locator as set forth in claim 8, wherein said microwave receiver further includes a power limiter, a signal input of the high-frequency amplifier being connected to the output of the receiving antenna via a signal output and a signal input of the power limiter.

10. A microwave locator as set forth in claim 7, wherein said preamplifier/demodulator is comprised of a first and second band-pass filter, a first and second clock rate amplifier, a first, second, third and forth low-frequency phase detector, a first and second amplifier, an adder and a subtracter, a signal input of the first band-pass filter being coupled to a signal output of the first phase detector, and a signal output of the first band-pass filter being connected to a signal input of the first clock rate amplifier, a signal input of the second band-pass filter being connected to a signal output of the second phase detector, a signal output of the second band-pass filter being connected to a signal input of the second clock rate amplifier, a signal output of the first clock rate amplifier being connected to signal inputs of the first and second low-frequency phase detectors, and a signal output of the second clock rate amplifier being connected to signal inputs of the third and forth low-frequency phase detectors, a second output of the modulator being connected to control inputs of the second and forth low-frequency phase detectors, and a third control output of the modulator being connected to control inputs of the first and third low-frequency phase detectors, wherein a phase of a control clock rate pulse sequence at the third output of the modulator is shifted at a quarter period relative to that of a clock rate pulse sequence at the second output thereof, outputs of the first and forth low-frequency phase detectors are connected to a first and second input of the subtracter, outputs of the second and third low-frequency phase detectors are connected to a first and second input of the adder, an output of the adder is connected to an input of the first amplifier, and an output of the subtracter is connected to an input of the second amplifier, outputs of the first and second amplifiers being connected to the signal processing unit.

11. A microwave locator as set forth in claim 10, wherein said first and second amplifiers are circuits comprised of a high-pass filter, an intermediary amplifier, a low-pass filter and a signal amplifier, all connected in series.

12. A microwave locator as set forth in claim 11, wherein each of said first and second amplifiers is multi-channel, one channel being used to extract a modulated component corresponding to a living object'"'"'s breath, a second channel being used to extract a modulated component corresponding to a living object'"'"'s heart, and a third channel being used to extract a modulated component corresponding to living object'"'"'s movements.

13. A microwave locator as set forth in claim 10, wherein said measurement unit in the signal processing unit includes a first and second amplitude detector, a detected signal combiner, an integrator and a first and second comparator, a monostable flip-flop, a counter and an alarm, a signal input of the first amplitude detector being connected to a signal output of the first amplifier, a signal input of the second amplitude detector being connected to a signal output of the second amplifier, outputs of the first and second amplitude detectors being connected to a first and second input of the detected signal combiner, respectively, an output of the detected signal combiner being connected to a signal input of the integrator and a signal input of the first comparator, a second input of the comparator being a threshold input, a signal output of the integrator being connected to a signal input of the second comparator, another input of the second comparator being a threshold input, while an output thereof is connected to the alarm, the signal output of the integrator being further connected to a first input of the indicator in the signal processing unit, a signal output of the first comparator being connected to a signal input of the monostable flip-flop having a signal output connected to the counter, and an output of the counter being connected to a second input of the indicator.

14. A microwave locator as set forth in claim 5, wherein said transmitter further includes a power amplifier, a signal output of the first pulse modulator being connected to an input of the transmitting antenna via a signal input and output of the power amplifier.

15. A microwave locator as set forth in claim 5, further comprising a circulator, wherein the transmitting antenna and the receiving antenna form a single receiving/transmitting antenna, the first pulse modulator being connected to the receiving/transmitting antenna via a first branch of the circulator and a second branch thereof in circulation direction, the microwave receiver being coupled to the receiving/transmitting antenna via the second and a third branch of the circulator in the circulation direction.

16. A microwave locator as set forth in claim 5, wherein said modulator is comprised of a clock generator and a timing unit having a clock input connected to an output of the clock generator, outputs of the timing unit being a first, second, third and forth output, respectively, of the modulator, the signal processing unit including a measurement unit, a control unit and an indicator, wherein an input of the measurement unit is an input of the signal processing unit, a control output of the measurement unit is connected to an input of the control unit, and a signal output thereof is connected to a signal input of the indicator, a first control output of the control unit is connected to a control input of the timing unit, and a second control output of the control unit is connected to a control input of the indicator.