JPH09211117A - Movement detection radar device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a movement detection radar device wherein the electromagnetic wave of a microwave band being put to practical use for the purpose of detection of presence of a human life or guard at a disaster site is used without lowering the performance thereof due to a slight shock of the device itself. SOLUTION: The phase of a station transmitting high frequency signal 106 is modulated with a phase modulator by the use of the minute movement signal 105 of output of a tremor sensor 14 for detecting the tremor of an antenna and made a station transmitting high frequency signal 107. Thereby an unnecessary component included in a receiving high frequency signal 104 is eliminated, furthermore the unnecessary component due to the slight shock of the antenna 4 included in an output low frequency signal 109 is eliminated with a low frequency variable attenuator 13 and a low frequency adder 12 by the use of minute moving signal 105, and a low frequency signal 110 which includes only the movement of a moving electric wave reflection object 6 is obtained.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a motion detection radar device that uses electromagnetic waves in the microwave band, mainly for the purpose of detecting the existence of life and security.

2. Description of the Related Art When an electromagnetic wave in the microwave band is radiated by an antenna and a reflected wave from a radio wave reflecting object in the energy irradiation space of the antenna is received, if the object is moving, the general In addition, the received wave undergoes a Doppler shift in its frequency, and if the frequency shift is measured, the relative velocity of the moving object to the antenna can be remotely observed, and is widely applied. However, if the speed of the moving radio wave reflector is very slow and becomes a slight movement, and there is only a phase change within 1/2 wavelength of the radiated electromagnetic wave, the change in frequency becomes unobservable. In this case, the receiver adjusts the phase and amplitude of the locally transmitted high frequency power so that the non-modulated component of the received signal is erased, mixes it with the received signal, and leaves only the modulated component. It is reported by Chan et al. (An X) that a signal having information about a change in distance in its envelope amplitude can be obtained by phase detection using it.
-Bandmicrowave life detec
section system. IEEE Transact
ions on BiomedicalEngine
ring; Vol. BME-33, No. 7 July
1986), it is possible to detect a relatively small and gentle movement of the radio wave reflecting object by detecting the signal. Based on this principle, the characteristic vibrations of the body surface due to human respiration and heart palpitations, which are conductors, are detected by the microwave reflection signal, and beyond the obstacles that can transmit radio waves such as concrete walls and rubble. Many devices have been proposed that are applied to the detection of the presence of other living organisms and the contactless monitoring of vital signs of patients. Many proposals have been made for various signal processing methods in the microwave stage and low-frequency stage of such an apparatus, but the basic principle is as described above. Since this detection principle after all measures a slight change in the distance from the antenna to the target reflection surface, if the antenna moves slightly, the component in the distance direction directly affects the output. When you want to use this motion detection radar device for the purpose of detecting living things at the scene of fire or immediately after the earthquake, the radar device is a small parabola or a structure with the same effect (even if it is integrated with the detection electronic device. (Including) is commonly used. It is extremely difficult to securely fix this antenna in an emergency such as a disaster site so that it will not vibrate or move. There is a limit to a person's stationary effort when trying to search quickly by carrying it on a hand-held or simple support. In addition, there is vibration of the floor and the ground, and the desired respiratory and heartbeat signals are extracted from the combined signals of them, even if various advanced signal processing as described later is applied to the output signal. However, there is a limit to the practical value. For example, it is said that the amplitude due to respiration in front of the human torso is about 0.3 mm at the most, while it can be easily imagined that a person standing with the antenna and the device on his shoulder swings about several mm. In this case, the fact that the antenna fluctuates means that the total reflection power undergoes modulation, and furthermore, the modulated wave component due to respiration from a distant limited area is sufficiently masked, making it impossible to identify the target signal. Become.

SUMMARY OF THE INVENTION The present invention solves the method of compensating for the weakness of the motion detecting radar device which is weak against vibration.

In the figure, an antenna 4 is shown.
The shake sensor 14 for detecting the slight movement of the sensor is attached to the antenna 4, and the fine movement signal 105 output from the shake sensor 14 is used to change the phase of the unmodulated local high frequency signal 106 mixed with the received high frequency signal 104 into the phase modulator 15 By further modulating the signal with the local high frequency signal 107, the antenna 4
Of the stationary radio wave reflecting object 5 modulates the reflected component 102 to generate an output low-frequency signal 109 by eliminating unnecessary components included in the received high-frequency signal 104, and the fine movement of the antenna 4 causes movement. The unnecessary component contained in the output low frequency signal 109 generated by modulating the reflected component 103 from the radio wave reflecting object 6 is adjusted by adjusting the amplitude of the fine motion signal 105 of the antenna 4 through the low frequency variable attenuator 13 and inverting the polarity to reduce the amplitude. The low frequency signal 110 of the moving low frequency signal 110 of the radio wave reflecting object 6 is obtained by erasing by adding to the output low frequency signal 109 using the frequency adder 12. [Operation] The local high frequency signal 106 for eliminating the unmodulated reflected radio wave component 102 is modulated by the phase modulator 15 using the fine movement signal 105 of the antenna 4 by the vibration of the antenna 4 to the unmodulated reflected radio wave 102. The modulation component contained in the received high frequency signal 104 due to the reflected power 102 from the stationary radio wave reflecting object 5 due to the shaking of the antenna 4 is continuously erased by setting in advance when the device is adjusted so that it is just canceled. The output low-frequency signal 109 of the motion obtained from the reflected radio wave 103 from the radio wave reflecting object 6 having the desired motion is selectively obtained. Further, the fine movement component of the antenna 4 included in the output low-frequency signal 109 is also included in the output low-frequency signal 109 due to the modulation due to the shake of the antenna 4 that reaches the reflected power 103 from the moving radio wave reflecting object 6.
The fine movement signal 105 can be removed by adjusting the amplitude using the low frequency variable attenuator 13, reversing the polarity, and adding it to the output low frequency signal 109 by the low frequency adder 12. [Embodiment] FIG. 1 is an example of the configuration of a motion detection radar device according to the present invention. This configuration is almost the same as the system by Chen et al., And the shake detection sensor 14 fixed to the antenna 4 in the figure, the phase modulator 15 using the signal, the low frequency variable attenuator 13, and the low frequency adder 12 are The difference is that it is included. Hereinafter, this operation will be described. The phase-stabilized high frequency oscillator 1 generates microwave continuous wave power of about 1 to 10 GHz. This frequency is selected according to the purpose of use and environment. For example, if the target search space is limited to detect very small movements, a relatively high frequency should be selected, and if a large search space is assumed, a low frequency with a small propagation loss is selected. This high frequency power is partially divided by the high frequency directional coupler 2 for use for the purpose described later, and the main power is coupled to the microwave antenna 4 via the circulator 3 and radiated to the space to be searched. . The component reflected back from the search space to the antenna 4 is the component 102 of the reflected wave from the stationary radio wave reflecting object 5 (for example, a stationary metal object such as a car) and the moving radio wave reflecting object 6 in the search space.
There is a component 103 that is reflected back to (for example, a person is present and their body surface is moving due to breathing). The latter is subject to phase modulation due to its movement. These reflection components 102 and 103 are collectively input as a received high frequency signal 104 to one of the input ports of the high frequency directional coupler 7 through the circulator 3. On the other hand, the divided component 111 from the high-frequency directional coupler 2 of the high-frequency oscillator 1 is for canceling the component of the reflected received power corresponding to the reflected power 102 from the stationary radio wave reflecting object 5. The signal 111 passes through the high frequency directional coupler 16 and is then adjusted in amplitude and phase by the high frequency variable attenuator 8 and the high frequency variable phase shifter 9 to become a local high frequency signal 106, and further, the antenna 4 required in the present invention. A local oscillator high-frequency signal 107 is input to the other input port of the high-frequency directional coupler 7 via a phase modulator 15 that provides a phase modulation corresponding to the fluctuation of the signal. When the antenna 4 is stationary and does not swing, the high frequency variable attenuator 8 and the high frequency variable phase are such that the divided high frequency component 111 is equal to the amplitude of the reflection component 102 received from the stationary radio wave reflecting object 5 and the phase is inverted. The local high frequency signal 106 is adjusted by the shifter 9. In the phase modulator 15 required in the present invention, when the antenna 4 is stationary, the locally generated high frequency signal 106 is added to the high frequency directional coupler 7 as the locally generated high frequency signal 107 without any modulation. Therefore, the component of the reflected input 102 from the stationary radio wave reflecting object 5 is erased by the high frequency directional coupler 7, and only the received high frequency signal 108 which is modulated by the movement from the moving radio wave reflecting body 6 remains and the high frequency direction is left. Sex coupler 7
Will be obtained as output. When the antenna 4 is shaking, the reception reflection component 10 from the stationary radio wave reflection object 5
Similarly, the component 103 from the radio wave reflector 6 in which 2 is moving is also modulated by the vibration of the antenna 4. In response to this, the phase modulator 15 further modulates the divided local high frequency signal 106 by the fine movement signal 105 from the shake sensor 14 corresponding to the amount of shake of the antenna 4.
The depth of the modulation is set in the direction in which the radio wave is reflected toward the stationary radio wave reflecting object 5 while the device is operating in advance and vibration is applied to the target radio wave reflecting object 102 which is stationary on the antenna 4. It is realistic to adjust so that the output of the sex coupler 6 becomes zero. By setting the modulation depth of the phase modulator 15 in this way, even if the antenna 4 moves, the component reflected without modulation in the search space is erased by the output of the directional coupler 6. An example of the shake sensor 14 that detects the shake of the antenna 4 is a method of measuring acceleration by an acceleration sensor and integrating the acceleration. Examples of the shake of the antenna 4 to be compensated are relatively low due to a slight shake of a person who supports the object, a shake of the floor due to the movement of the elevator in the building, and a vibration of a large rotating machine such as a compressor. It is a small amplitude swing of the frequency. Received high frequency signal 10 modulated from the remaining moving radio wave reflecting object 6
8 is amplified by the high frequency amplifier 10 if necessary, and then input to the double balanced mixer 11. The reference signal of the double balanced mixer 11 is also the high frequency oscillator 1
Of the continuous wave 11 obtained by dividing the output of
2 is used. The output low-frequency component of the table balanced mixer 11 is the output low-frequency signal 109 for the purpose of corresponding to the movement of the moving radio wave reflecting object 6. However, when the antenna 4 is shaking, the received radio wave 103 from the moving radio wave reflecting object 6 is also modulated by the shaking of the antenna 4 at the same time,
The output low-frequency signal 109 includes the movement of the antenna 4 and is mixed with the movement such as human breathing in the search space to make identification difficult. However, in this case, since the signals are mixed in at a low frequency, it is possible that the target signal can be selectively extracted by performing processing such as filtering and frequency analysis.
However, since the swing signal of the antenna 4 can be used in this system, the signal-to-noise ratio can be further improved. That is, the amplitude of the low-frequency antenna 4 fine movement signal 105 is adjusted in advance by the low-frequency variable attenuator 13 so as to be equal to the amplitude of only the movement of the antenna 4 appearing in the output low-frequency signal 109, and the low-frequency addition is performed. By inverting and adding the phase in the device 12, the sway of the antenna 4 is eliminated and the low frequency signal 110 of the motion of the moving radio wave reflecting object 6 is obtained. [Effects of the Invention] By the operation as described above, the high-frequency component modulated by the vibration of the motion detection radar device itself (strictly speaking, its antenna) is selectively erased, and then the output low-frequency signal 109 is further obtained. The signal processing using the swing signal of the antenna 4 makes it possible to extract the motion occurring in the search space with a good signal-to-noise ratio. When using the motion detection radar device to detect people who have fallen over in the smoke or in the stricken area after an earthquake due to smoke, or people under the rubble, the conventional motion detection radar device may cause sway. There is a risk that it cannot be used for emergencies because it is necessary to find a non-existent floor and prepare and fix a solid support stand such as a tripod. However, the motion detection radar device according to the present invention can be carried by an ambulance crew. Therefore, even if this method is not a universal method for finding lives, it has the advantage of being quick and of the safety of emergency personnel, and can be used as a complementary method to other methods. It can have a big meaning. The contents of the present invention are of course applicable not only to the device for the purpose of finding a human life but also to the case where the motion detecting device using the microwave is used for other purposes, based on the same principle and included in the scope of the claims of the present invention. As an example, when a motion detection radar device is applied to the purpose of measuring the distance between a vehicle running on the track and the track and the wall of the platform or tunnel, a measurement starting point is applied using the principle of the present invention. Thus, after the initial distance value is recognized when the vehicle is stopped, it is possible to continuously correct the error in which the measuring antenna on the vehicle shakes relative to the ground during traveling. By using recent microelectronic elements, the entire device including the microwave portion can be carried and operated by one person, and in this case, the present invention is particularly effective.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a motion detection radar device according to the present invention.

[Explanation of symbols]

 1. High frequency oscillator 2. High frequency directional coupler 3. Circulator 4. Antenna 5. Stationary radio wave reflector 6. Moving radio wave reflector 7. High frequency directional coupler 8. High frequency variable attenuator 9. High frequency variable phase shifter 10. High frequency amplifier 11. Double balanced mixer 12. Low frequency adder 13. Low frequency variable attenuator 14. Shake sensor 15. High frequency phase modulator 16. High frequency directional coupler 104. Received high frequency signal 105. Fine motion signal of antenna 4 106. Local high frequency signal 107. Local high frequency signal 108. Received high frequency signal 109. Output low frequency output 110. Low frequency output of movement

Claims (1)

[Claims] In the well-known motion detection radar device shown in the figure, a shake sensor 14 for detecting fine movement of the antenna 4 is attached to the antenna 4, and a fine movement signal 105 output from the shake sensor 14 is used to mix the received signal 104 with an unmodulated signal. By further modulating the phase of the local oscillator high-frequency signal 106 with the phase modulator 15 and setting it as the local oscillator high-frequency signal 107, the reception high frequency generated by the fine movement of the antenna 4 modulating the reflection component 102 from the stationary radio wave reflecting object 5. The unnecessary component contained in the signal 104 is eliminated to obtain the output low-frequency signal 109, and the reflected component 103 from the radio wave reflecting object 6 in which the fine movement of the antenna 4 is moving.
The unnecessary component contained in the output low-frequency signal 109 is modulated by the low-frequency variable attenuator 13 to adjust the amplitude, and the polarity is inverted. Low-frequency signal 1 of the motion of the radio wave reflecting object 6 which is deleted by adding to the frequency signal 109 to move
A motion detection radar device characterized by obtaining 10.