WO2021095891A1

WO2021095891A1 - Microwave sensor for security monitoring

Info

Publication number: WO2021095891A1
Application number: PCT/KR2019/015252
Authority: WO
Inventors: 김진명
Original assignee: 주식회사 제이씨에프테크놀러지
Priority date: 2019-11-11
Filing date: 2019-11-11
Publication date: 2021-05-20

Abstract

The present invention relates to a microwave sensor for security monitoring, wherein the microwave sensor uses microwave signals to recognize human bodies within a certain distance and monitor intrusions. The microwave sensor comprises a transmitter and a receiver installed a certain monitoring distance from the transmitter. The transmitter includes: a first voltage-controlled oscillator (VOC1) which generates and outputs an oscillation frequency (f1) having a certain period by using voltage (V) applied from the outside; and a transmission antenna (Tx) which amplifies the oscillation frequency generated in the first voltage-controlled oscillator, and transmits the amplified frequency to the outside. The receiver includes: a reception antenna (Rx) which receives signals transmitted from the transmission antenna (Tx) of the transmitter; a second voltage-controlled oscillator (VOC2) which generates and outputs an oscillation frequency (f2) having a certain period by using voltage (V) applied from the outside; an IF generating unit which generates an intermediate frequency (IF) by means of the difference between a signal (f1) received from the reception antenna (Rx) and a signal (f2) applied from the second voltage-controlled oscillator; a filter unit which filters the IF signal input from the IF generating unit into a certain band; a non-linear amplifying unit which amplifies the signal filtered in the filter unit to a signal of a certain level; and a DC converting unit which converts the signal amplified in the non-linear amplifying unit to DC voltage through a comparator on the basis of the voltage level (Vrms) of an IF signal component, and outputs the converted signal. The frequency of oscillations in the first voltage-controlled oscillator and the frequency of oscillations in the second voltage-controlled oscillator are set to be differently output to obtain an IF signal component that is constantly fixed to the frequency difference between the signal transmitted from the transmitter and the signal generated in the receiver. The present invention has a lower false-positive rate than existing microwave sensors.

Description

Microwave sensor for security surveillance

The present invention relates to a sensor for security monitoring, and more particularly, to a microwave sensor for security monitoring that recognizes a human body within a certain distance and monitors intrusion using a microwave signal.

In general, security systems are installed to protect lives and property from various crimes that may occur due to unauthorized contact or intrusion from outside in places or spaces that require protection of people and property. In this security system, various sensors are installed to detect external intrusion.

A sensor detects an external stimulus or signal, and is a device that detects an external signal or a dangerous signal that is difficult for human sense organs to detect and converts it into an electrical signal. Such sensors are widely used around us, such as endoscopes, stethoscopes, thermometers, X-ray scanners, magnetic resonance imaging devices (MRI), and infrared cameras. The endoscope uses light to show the inside of the stomach or intestines, and the stethoscope gives information about the heartbeat, breathing, and blood circulation through sound. Thermometers can measure body temperature in the body using heat, and X-ray cameras and magnetic resonance imaging devices indirectly show the state of the body using electromagnetic waves that cannot be seen with an endoscope. Infrared cameras change the infrared light emitted by an object into visible light that can be seen, so you can see your surroundings better.

In addition, as one of the sensing technologies, radar can accurately measure the exact distance to the object and the relative speed of the object to the observation point. Radar devices usually operate by emitting electromagnetic waves of microwaves onto an object and receiving the electromagnetic waves reflected from the object. The processed signal is converted into a form that can be used by a peripheral device controlled by an operator or radar. Information about the target is displayed on the screen of the cathode ray tube. The most widely used pulsed radar transmits radio energy in the form of very strong pulses. Since the continuous wave radar transmits the transmission signal in a continuous form instead of a short pulse, the echo is continuously received. Simple continuous wave radars cannot measure distance, but more sophisticated frequency modulated radars do. Instead of radio frequency, ray radar emits laser light with a very narrow width.

In addition, the Doppler radar uses the Doppler effect of radio waves, and detects a target moving by a difference between the frequency of the radar wave transmitted toward the target and the frequency reflected. It is used for weather radar, self-supporting navigation system of aircraft, and military radar. In meteorological use, the change in wind speed occurring inside the cloud is measured. In the self-supporting navigation system, the current position is calculated by measuring the speed of radio waves reaching the ground. In military radars, pulsed Doppler radars that use a single pulse signal to capture and track only targets moving in reflected waves on the surface and sea level are the mainstream.

In FIG. 1, in the conventional Doppler radar having a transceiver structure, a microwave signal generated by a VCO inside the transceiver, for example, 24 to 24.25 GHz, is output through a Tx antenna, and the output microwave signal is It is reflected by the target and received by the Rx antenna. In addition, when the target moves, the signal received by the Rx antenna is received by the Rx antenna by converting an arbitrary Doppler piece from which the Tx signal is relatively shifted to a frequency signal according to the moving speed of the target. Therefore, as the frequency signal of the VCO and the received frequency signal pass through the mixer, the difference between the two signals is detected as a Doppler signal, which becomes an IF (baseband) signal of a specific voltage level and is transmitted to the signal processing circuit. At this time, the Doppler signal detected as the IF signal generates a signal with a motion of a different voltage level only during the time the target is moving, and when the motion disappears, the IF signal also becomes 0.

Conventionally, infrared sensors mainly used to detect the movement of human body or objects have a short sensing distance and a slow response speed, and a high false report rate against interference or disturbances such as fog, fallen leaves, tree branches, birds, insects, temperature, sunlight, etc. , There is a problem that the error range of setup is narrow. In addition, the conventional Doppler radar requires processing of the received signal in the process of detecting the signal to use the modulation signal for long-distance transmission of radio waves or to use the Doppler signal as it is. There was a problem with using the software.

As a prior art related to the present invention, a motion detection apparatus using a Doppler radar of Patent Document 1 includes a signal processor for receiving a Doppler signal through the Doppler radar and calculating a power average value of frequency components included in the Doppler signal, and A motion determiner that receives the average power values calculated for each of the plurality of Doppler signals continuously received through the Doppler radar from the signal processor, and analyzes the change of the average power values over time to determine the type of motion of the reflector. A configuration to include is disclosed.

[Prior technical literature]

[Patent Literature]

(Patent Document 1) Republic of Korea Patent Publication No. 10-2019-0021906 (published on March 6, 2019)

The present invention is to solve the above problem, and an object of the present invention is to monitor intrusion at a straight distance set by a microwave sensor for security monitoring using a pair of transmitters and receivers in a Doppler radar transceiver structure.

In addition, it is another object of the present invention to reduce manufacturing costs and improve utilization by simplifying circuits as well as improving erroneous baud rates.

In order to achieve the above object, the present invention is a first voltage controlled oscillator (VCO1) for generating and outputting an oscillation frequency (f1) of a certain period with a voltage (V) applied from the outside, and the first voltage. A transmitter including a transmission antenna (Tx) for amplifying the oscillation frequency generated by the control oscillation unit and transmitting the amplified oscillation frequency to the outside; A receiving antenna (Rx) for receiving a signal transmitted from the transmitting antenna (Tx) of the transmitter, and a second voltage-controlled oscillation unit that generates and outputs an oscillation frequency (f2) of a certain period with a voltage (V) applied from the outside ( VCO2), an IF generator that generates an intermediate frequency (IF) frequency by a difference between the signal f1 received from the receiving antenna Rx and the signal f2 applied from the second voltage controlled oscillator, and the IF generation A filter unit that filters the IF signal input from the unit into a predetermined band, a nonlinear amplification unit amplifying the signal filtered by the filter unit into a signal of a predetermined level, and the signal amplified by the nonlinear amplification unit is applied to the voltage of the IF signal component. It includes a DC conversion unit for converting and outputting a DC voltage through a comparator based on the level (Vrms), and includes a receiver installed at a predetermined monitoring distance from the transmitter, and It features a microwave sensor for security monitoring that always acquires a fixed IF signal component as much as the frequency difference between the signal transmitted from the transmitter and the signal generated from the receiver by setting the frequency oscillated by the 2 voltage controlled oscillation unit to be output differently. to be.

In addition, in the present invention, a determination means for determining an abnormal state based on the voltage level Vrms output from the DC converter may be further included.

In addition, in the present invention, the determination means determines that it is an abnormal state that can generate an alarm according to the intrusion of an intruder in the monitoring area when 0 to 0.5V is applied from the DC converter, and 1.2 to 2.4V at the DC converter. When is applied, it is determined that monitoring is performed according to the entry of an intruder into the surveillance area, and when 2.5~3.3V is applied from the DC converter, it can be judged as a normal surveillance state with no intruders in the surveillance area.

Further, in the present invention, the frequency f1 oscillated by the first voltage controlled oscillator and the frequency f2 oscillated by the second voltage controlled oscillator may be configured with different frequencies.

In addition, in the present invention, the nonlinear amplification unit may further include a differentiator for differential processing such that the output of the IF signal swings toward the + voltage before amplifying the output voltage according to real-time changes.

According to the present invention, in order to use a modulated signal in a conventional microwave sensor or use a Doppler signal as it is, it is possible to overcome the disadvantage of using software while using a very complex circuit and expensive parts in a receiver. The sensor can be implemented with an equivalent or higher level by simply inserting a circuit without software configuration, and there is an improved advantage that can improve the erroneous baud rate compared to the conventional microwave sensor.

1 is a diagram showing the operation of a conventional Doppler radar.

2 is a block diagram showing a microwave sensor for security monitoring according to an embodiment of the present invention.

3 is an exemplary view showing the operation of the microwave sensor for security monitoring according to the present invention.

4 is a diagram illustrating a condition determined by a determination means according to a voltage level generated by an action of a microwave sensor for security monitoring according to the present invention.

Hereinafter, an embodiment of a microwave sensor for security monitoring according to the present invention will be described in detail with reference to the accompanying drawings.

In FIG. 2, the transmitter 10 and the receiver 20 are spaced apart by a set monitoring distance (d) within a certain range for transmitting and receiving microwave frequencies. It is preferable that the transmitter 10 and the receiver 20 are correspondingly installed so that they can face each other.

The first voltage controlled oscillator (VCO1) 11 installed in the transmitter 10 generates and outputs the oscillation frequency f1 of a predetermined period with the first voltage V(t1) applied from the outside. Then, the transmission antenna Tx amplifies the oscillation frequency f1 generated by the first voltage controlled oscillator 11 and transmits it to the receiver 20 installed within a predetermined monitoring distance d.

The reception antenna Rx installed in the receiver 20 receives the signal transmitted from the transmission antenna Tx of the transmitter 10. In addition, the second voltage controlled oscillation unit VCO2 generates and outputs the oscillation frequency f2 of a predetermined period with the second voltage V(t2) applied from the outside.

The IF (Intermediate Frequency) generator 22 generates an IF signal by a difference between the signal f1 received from the receiving antenna Rx and the signal f2 applied from the second voltage controlled oscillator 26. . Therefore, the generation of the IF signal generated by the IF generator 22 has the same effect as that the Doppler frequency is continuously generated in real time, and the IF generator 22 generates a constant voltage level without additional modulation signal processing. Signal can be output.

In addition, the nonlinear amplification unit 24 differentiates the signal filtered by the filter unit 23 and amplifies the signal to a predetermined level. The nonlinear amplifier 24 is for increasing the transmission/reception distance in a state in which the power line gain between the transmitter 10 and the receiver 20 is fixed. This is because a typical low-frequency amplifier can easily saturate in a high-frequency component, so when amplifying the IF signal as it is, there is a limit to increasing the transmission/reception distance. For this reason, the IF signal component must be amplified while filtering by the filter unit 23, because a loss occurs in the voltage level (Vrms) value of the IF signal component during the filtering process, resulting in a reduction in the amplification effect. Therefore, by designing the nonlinear amplification unit 24 including the differentiator 27, the swing reference voltage level is adjusted to the output amplified by the nonlinear amplification unit 24 so that energy is carried further by swinging toward the + voltage of the IF signal component. I implemented it.

In this way, the filter unit 23 filters the IF signal input from the IF generator 22 with a predetermined bandwidth. A physical signal generated by the transmitter 10 and the receiver 20 may be detected through a process of filtering the IF signal of a constant voltage level by the filter unit 23 and amplifying it by the nonlinear amplifying unit 24. Moreover, it is desirable to determine the IF signal component at about 2 MHz or less in consideration of the op-amp characteristics and filter characteristics that can be reflected in the design, and design to avoid the Doppler frequency generated by objects or human bodies. good.

The DC conversion unit 25 converts the signal amplified by the nonlinear amplification unit 24 into a DC voltage through a comparator based on the voltage level (Vrms) of the IF signal component and outputs it.

Therefore, the frequency f1 oscillated by the first voltage controlled oscillator 11 of the transmitter 10 and the frequency f2 oscillated at the second voltage controlled oscillator 26 of the receiver 20 are set to be output at different frequencies. Thus, an IF signal that is always fixed as much as the frequency difference between the signal transmitted from the transmitter 10 and the signal generated by the receiver 20 is obtained.

The determination means 30 determines an abnormal state based on the voltage level Vrms output from the DC converter 25. That is, the determination means 30 may determine the abnormal state when 0V is applied from the DC converter 25, and determine the normal state when 1 to 3V is applied by the DC converter 25.

The control center 40 allows the monitoring person to generate an alarm or monitor according to the intrusion, approach, or passage of an intruder in the monitoring area with a signal received from the determination means 30.

The operation of the microwave sensor for security monitoring according to the present invention will be described.

In FIG. 3, the microwave sensor for security monitoring is characterized by configuring a conventional Doppler radar transceiver as a microwave sensor.

A first voltage V(t1) applied to the first voltage controlled oscillator 11 of the transmitter 10 and a second voltage V(t2) applied to the second voltage controlled oscillator 26 of the receiver 20 )) is an input voltage for determining the oscillation frequencies VCO(f1) and VCO(f2) of different Doppler radar transceivers, respectively. The oscillation frequencies VCO(f1) and VCO(f2) can be appropriately adjusted and used for each frequency according to the application range. Therefore, the frequencies f1 and f2 are frequency components produced by the respective oscillation frequencies VCO(f1) and VCO(f2). _{In addition, the Doppler frequency f IF} generated by the IF generator 22 of the receiver 20 is a baseband signal generated by a difference between the transmission signal f1 and the reception signal f2.

The transmission signal f1 transmitted from the transmission antenna tx of the transmitter 10 is transmitted to the reception antenna Rx of the receiver 20 through the monitoring distance d within a certain monitoring area.

At this time, in the mixer of the IF generator 22 of the receiver 20, the transmission signal f1 of the transmitter 10 and the oscillation frequency VCO(f2) set differently are mixed, and the Doppler frequency f, which is the IF signal by the difference between the two frequencies, is mixed. _IF ) is continuously generated through real-time. When the Doppler frequency (f _IF ) is generated, the voltage level (Vrms) is always generated in the baseband by the frequency component (peak to peak) of the _{Doppler frequency (f IF ).} This voltage level Vrms indicates that the transmission/reception signals are connected without being disconnected.

If an object exists to attenuate or prevent reaching the transmission signal of the transmitter 10 within the monitoring distance (d), the voltage level (Vrms) of the frequency component of _{the Doppler frequency (f IF) becomes weaker than the normal state or becomes 0V.} It can detect an abnormal condition off

Further, in FIG. 4, when the first voltage level output from the DC converter 25 from the determination means 30 is in the range of 3.3 to 2.5V, it is determined as a normal monitoring state, but the control center 40 detects an intruder in the monitoring area. When the second voltage level output from the DC conversion unit 25 is in the range of 2.4 to 1.2 V, the determination means 30 determines that it is in a normal monitoring state, but is monitored by the control center 40. It communicates that an intruder is entering the area and needs to be monitored. In addition, when the third voltage level output from the DC conversion unit 25 by the determination means 30 is in the range of 0.5 to 0V, it is determined as a normal intrusion state and an alarm signal is generated, and the control center 40 is sent to the monitoring area. It communicates that the intruder is passing through.

Therefore, the microwave sensor for security monitoring of the present invention can specify and set the IF frequency band disturbed by the human body, and simply amplify the IF frequency or change the voltage level (peak to peak) to extend the monitoring distance (d). Since it can be used by changing and outputting the DC voltage displacement, it has the advantage of improving the erroneous baud rate compared to the conventional microwave sensor.

In the above description, the present invention has been illustrated and described in connection with specific embodiments, but it is understood that various modifications and changes are possible within the scope of the spirit and scope of the invention indicated by the claims. Anyone who has it will be easy to know.

Claims

A first voltage controlled oscillator (VCO1) that generates and outputs the oscillation frequency f1 of a certain period with the voltage (V) applied from the outside;

A transmitter including a transmission antenna (Tx) for amplifying the oscillation frequency generated by the first voltage controlled oscillation unit and transmitting the amplified oscillation frequency to the outside;

A reception antenna (Rx) for receiving a signal transmitted from the transmission antenna (Tx) of the transmitter,

A second voltage controlled oscillation unit (VCO2) that generates and outputs an oscillation frequency (f2) of a certain period with the voltage (V) applied from the outside, and

An IF generator that generates an intermediate frequency (IF) frequency by a difference between the signal f1 received from the receiving antenna Rx and the signal f2 applied from the second voltage controlled oscillator,

A filter unit for filtering the IF signal input from the IF generation unit into a predetermined band,

A nonlinear amplification unit amplifying the signal filtered by the filter unit into a signal of a predetermined level,

A DC converter configured to convert the signal amplified by the nonlinear amplification unit into a DC voltage through a comparator based on the voltage level (Vrms) of the IF signal component and output it, the receiver installed at a predetermined monitoring distance from the transmitter; Including,

By setting the frequency oscillated by the first voltage-controlled oscillator and the frequency oscillated by the second voltage-controlled oscillator to be output differently, an IF signal component that is always fixed as much as the frequency difference between the signal transmitted from the transmitter and the signal generated by the receiver is obtained. A microwave sensor for security surveillance.
The microwave sensor for security monitoring according to claim 1, further comprising a determination means for determining an abnormal state based on a voltage level (Vrms) output from the DC converter.
The method according to claim 2, wherein the determination means determines that it is an abnormal state that can generate an alarm according to the intrusion of an intruder in the monitoring area when 0 to 0.5V is applied by the DC converter, and 1.2 to 2.4V at the DC converter. When is applied, it is judged to be monitored according to the entry of an intruder into the surveillance area, and when 2.5~3.3V is applied from the DC converter, it is judged as a normal surveillance state with no intruders in the surveillance area, a microwave sensor for security monitoring.
The microwave sensor according to claim 1, wherein a frequency (f1) oscillated by the first voltage-controlled oscillation unit and a frequency (f2) oscillated by the second voltage-controlled oscillation unit are made of different frequencies.
The microwave sensor of claim 1, wherein the nonlinear amplifying unit further comprises a differentiator for differential processing such that the output of the IF signal swings toward the + voltage before amplifying the output voltage according to real-time changes.