CN210514614U - Motion detection system - Google Patents
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Abstract
A motion detection system belongs to the fields of motion signal detection, intelligent sampling, wireless monitoring and the like. The motion detection system comprises a transmitting module, a receiving module, a first antenna, a second antenna and a transistor containing a heterojunction; the transmitting module controls the first antenna to transmit electromagnetic waves to cover the motion detection region, the original electromagnetic field distribution is disturbed by the moving object in the motion detection region, the second antenna receives electromagnetic signals with different powers and feeds the electromagnetic signals into the transistor with the heterojunction, the transistor with the heterojunction converts the received power information into frequency information, the frequency information is transmitted to the first antenna through the second antenna and is finally transmitted to the receiving module, and the receiving module judges whether the moving object exists in the detection region according to the received frequency information. The utility model discloses not only can survey the object that the rate of motion is slow, small, high low, can also utilize the network deployment that contains the heterojunction module to arrange the precision that improves the detection, have simultaneously that detection system and algorithm are simple, advantage with low costs.
Description
Technical Field
The invention belongs to the fields of motion signal detection, intelligent sampling, wireless monitoring and the like, and particularly relates to a motion detection system.
Background
The motion detection technology is generally applied to the fields of security and protection control, wireless monitoring, intelligent sampling, object motion analysis and the like. Conventional motion detection techniques can be generally classified into two types: one is a motion detection method based on the doppler effect, and the other is a motion detection method based on image acquisition.
The principle of the motion detection method based on the Doppler effect is that the wavelength of the object reflection changes due to the relative motion speed of a wave source and an observer. When the moving object approaches the detector, the wave is compressed, the wavelength becomes shorter and the frequency becomes higher (blue shift); conversely, when the moving object is far from the person to be detected, the wavelength becomes longer and the frequency becomes lower (red shift). The higher the relative motion speed of the detected object, the more obvious the blue (red) shift effect is, so that the motion condition of the object can be reversely deduced by the frequency change of the detected electromagnetic wave. When the detection method is applied, fixed-frequency electromagnetic waves are firstly emitted, and the movement information of a measured object is obtained by detecting the frequency of echo signals. The method is mainly used for detecting high-speed moving objects, and for objects with low moving speed, small size and low height, echo signals are usually difficult to distinguish or covered under noise due to weak blue (red) shift effect or low echo power, so that accurate detection is difficult to realize through the method. The motion detection method based on image acquisition is to perform real-time image monitoring on an area to be detected and compare acquired digital image signals to perform algorithm analysis, thereby obtaining the motion state of an object in the area. The detection method has the advantages of multiple detection targets and capability of realizing area detection, however, the detection method has harsh detection environment and limited identification distance, generally belongs to an optical equipment detection system, and has generally higher cost and complex processing algorithm.
In the field of motion detection based on the doppler effect, generally, radar is used to emit electromagnetic waves to detect an object, when the object moves, the reflected electromagnetic waves are blue (red) shifted, and the motion of the object can be inverted by detecting the frequency change of the reflected electromagnetic waves. Based on the design idea, a motion Detection system designed by using the Doppler effect is generally shown as [ dry Detection and Tracking Based on Phase-Interferometric Radar, Michael Jian, IEEE,2018 ] in fig. 1, and the Detection system performs algorithm analysis on the interference result of the reflected electromagnetic wave and the original electromagnetic wave to obtain the blue (red) shift information of the reflected electromagnetic wave, so as to reversely deduce the motion condition of the detected object. However, for an object with a slow moving speed, a small size and a low height, due to a weak blue (red) shift effect or a small echo power, an echo signal is usually not easily distinguished or masked under noise, and is difficult to accurately detect by the method.
The motion Detection technology based on digital Image recognition reported in 2006 has the principle as shown in fig. 2 [ see, for example, saintmotion Information Detection technology Using Weighted boundary Image and motion Vector, Yeon-sung Choi, IEEE 2006 ]. However, the detection system and algorithm are complex and the image information of the moving object must be completely acquired.
Disclosure of Invention
The invention aims to provide a novel motion detection system and a detection method aiming at the defects in the background technology.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
a motion detection system comprises a transmitting module, a receiving module, a first antenna, a second antenna and a transistor with a heterojunction, wherein the first antenna is connected with the transmitting module and the receiving module, and the second antenna is connected with the transistor with the heterojunction; the transmitting module controls the first antenna to transmit electromagnetic waves to cover the motion detection area, the original electromagnetic field distribution is disturbed by the moving object in the motion detection area, therefore, the second antenna can receive electromagnetic signals with different powers and feed the electromagnetic signals into the transistor with the heterojunction, the transistor with the heterojunction converts the received power information into frequency information, the frequency information is transmitted to the first antenna through the second antenna and finally transmitted to the receiving module, and the receiving module can judge whether the moving object exists in the detection area according to the received frequency information.
Further, the transistor containing the heterojunction may be a heterojunction bipolar transistor or a Field Effect Transistor (FET), etc.; wherein the field effect transistor may be a metal-oxide semiconductor field effect transistor (MOSFET) or a High Electron Mobility Transistor (HEMT).
Further, the power information received by the second antenna is determined by the power of the electromagnetic wave transmitted by the first antenna and the moving object in the motion detection area.
A method of motion detection, comprising the steps of:
the transmitting module transmits electromagnetic waves with specific frequency to cover the motion detection area, and the shape and the range of the detection area are mainly determined by the directional diagram of the second antenna;
the transistor containing the heterojunction is placed at a certain position or a plurality of positions of the motion detection area and receives electromagnetic signals with different powers of the motion detection area at the position;
the transistor containing the heterojunction converts the power information of the received electromagnetic signal into frequency information;
when a moving object enters the detection region, the distribution of the electromagnetic field in the detection region is inevitably changed, so that the power received by the transistor with the heterojunction is changed, the change of the frequency information is generated, the receiving module detects the change of the frequency information, and the existence of the moving object in the detection region is obtained according to the frequency information.
Further, the received power information is determined by the power of the transmitted electromagnetic wave and the moving object in the motion detection area.
Compared with the prior art, the invention has the beneficial effects that:
the invention provides a motion detection system and a detection method, wherein a first antenna transmits electromagnetic waves to electromagnetically cover a motion detection area, when a moving object exists in the detection area, the original electromagnetic field distribution is disturbed, a second antenna receives electromagnetic signals with different powers, and the power information is converted into frequency information through a transistor containing a heterojunction, so that the detection of the moving object is completed. The invention effectively solves the limitations of the traditional motion detection method, can detect objects with low motion speed, small volume and low height, can improve the detection accuracy by utilizing the networking arrangement containing the heterojunction modules, and has the advantages of simple detection system and algorithm and low cost.
Drawings
FIG. 1 is a block diagram of a motion detection system based on the Doppler effect as mentioned in the background art;
FIG. 2 is a block diagram of a motion detection system based on image acquisition as mentioned in the background art;
FIG. 3 is a schematic diagram of a motion detection system according to the present invention;
fig. 4 is a graph showing the relationship between the received power (P) and the output frequency (f) of the transistor including the heterojunction in the embodiment of the present invention.
Detailed Description
In order to facilitate the understanding of the technical contents of the present invention by those skilled in the art, the present invention will be further explained with reference to the accompanying drawings.
Fig. 3 is a schematic structural diagram of a motion detection system according to the present invention. The antenna comprises a transmitting module, a receiving module, a first antenna, a second antenna and a transistor containing a heterojunction, wherein the first antenna is connected with the transmitting module and the receiving module, and the second antenna is connected with the transistor containing the heterojunction. The transmitting module and the first antenna are used for covering an electromagnetic wave on a target area to be detected, when a moving object exists in the detection area, the original electromagnetic field distribution is disturbed, and the second antenna can receive different electromagnetic wave powers. The purpose of the transistor and the second antenna is to convert the received electromagnetic power information into frequency information and transmit the frequency information to the first antenna. The purpose of the first antenna and the receiving module is to receive the frequency signal transmitted by the second antenna and feed back the frequency signal in real time.
Wherein the transistor containing heterojunction can supply low-power radio frequency single-tone signal (frequency f) without supplying direct current1) Converted to another frequency-independent single tone signal (frequency f)2) And f is2And (4) controllable. When the second antenna feeds the received different electromagnetic wave power into the transistor containing the heterojunction, the ground state energy level E in the transistor0Is excited to a higher energy level Eh，EhWhen the unstable polariton on the energy level jumps to a lower energy level, irrelevant new frequency information can be generated, the new frequency is relevant to the fed-in electromagnetic wave power, and the detection of the moving object can be realized according to the characteristic that the frequency change is caused by the power change, as shown in fig. 4.
A method of motion detection comprising the steps of:
the transmitting module transmits electromagnetic waves with specific frequency to cover the motion detection area, and the shape and the range of the detection area are mainly determined by the directional diagram of the second antenna;
the transistor containing the heterojunction is placed at a certain position or a plurality of positions of the motion detection area, and receives electromagnetic signals with different powers of the motion detection area at the positions, when the power of the electromagnetic signals reaches the threshold power of the transistor containing the heterojunction, the transistor containing the heterojunction can generate new frequency signals with different specific frequencies from the specific frequency of the transmitting module, and the receiving module receives the frequency signals, so that real-time monitoring and monitoring can be achieved.
The motion detection method has the advantages of low cost and simple detection system and algorithm, and can be widely applied to the fields of wireless monitoring, intelligent regional sampling, moving object analysis and the like.
It will be appreciated by those of ordinary skill in the art that the embodiments described herein are intended to assist the reader in understanding the principles of the invention and are to be construed as being without limitation to such specifically recited embodiments and examples. Various modifications and alterations to this invention will become apparent to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.
Claims (3)
1. A motion detection system is characterized by comprising a transmitting module, a receiving module, a first antenna, a second antenna and a transistor with a heterojunction, wherein the first antenna is connected with the transmitting module and the receiving module, and the second antenna is connected with the transistor with the heterojunction; the transmitting module controls the first antenna to transmit electromagnetic waves to cover the motion detection area, the original electromagnetic field distribution is disturbed by the moving object in the motion detection area, the second antenna receives electromagnetic signals with different powers and feeds the electromagnetic signals into the transistor with the heterojunction, the transistor with the heterojunction converts the received power information into frequency information, the frequency information is transmitted to the first antenna through the second antenna and finally transmitted to the receiving module, and the receiving module can judge whether the moving object exists in the detection area according to the received frequency information.
2. The motion detection system of claim 1, wherein the transistor comprising a heterojunction is a heterojunction bipolar transistor or a field effect transistor; the field effect transistor is a metal-oxide semiconductor field effect transistor or a high electron mobility transistor.
3. The motion detection system of claim 1, wherein the power information received by the second antenna is determined by the power of the electromagnetic wave transmitted by the first antenna and the moving object in the motion detection region.
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| CN110221284A (en) * | 2019-07-05 | 2019-09-10 | 电子科技大学 | A kind of motion detection system and detection method |
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