CN103777203A - Microwave action detector - Google Patents

Abstract

The microwave motion detector includes: a transmitting device, which transmits a microwave signal to a space to be tested; a receiving device, which receives a reflected microwave signal reflected back from the space to be tested; a signal processing device, which processes the reflected microwave signal received by the receiving device to determine whether there is a disturbance in the space to be tested, and the signal processing device generates the microwave signal; and a path switching device, which is coupled to the signal processing device and the transmitting device, and the path switching device enables the multiple transmission paths through which the microwave signal passes to have different phase shifts.

Description

microwave motion detector

technical field

The invention relates to a microwave motion detector.

Background technique

Motion detectors are often used in security surveillance or presence recognition applications. Typically, motion detectors are implemented in infrared technology. However, infrared technology is prone to misjudgment due to the influence of ambient temperature, or even impossible to detect.

Microwave motion detectors use the Doppler principle to compare the phase difference between the transmitted signal and the received signal. If the phase difference changes, it means that there is a disturbance source in the environment.

However, although the traditional microwave motion detector has a simple structure, it needs to solve the problem of sensing zero point. Please refer to FIG. 1 , which shows a graph showing changes in sensing sensitivity of a conventional microwave-based motion detector. In FIG. 1 , the horizontal axis is the distance, and the vertical axis is the sensing sensitivity. The transmitting signal sent by the detector 100 will be reflected as a receiving signal after encountering the object under test 110 . It can be seen from FIG. 1 that at the position of the sensing zero point (that is, the sensing sensitivity is 0), it cannot be sensed (that is, if the object under test 110 is located at the sensing zero point, the detector 100 cannot sense analyte 110). Sensing nulls are common to single-frequency Doppler architectures, cannot be detected at these locations, and repeat with a period of every quarter of the wavelength of the electromagnetic wave. Conversely, where the sensing sensitivity is at its maximum, it is the optimum sensing point.

In addition, the microwave motion detector adopts the continuous wave method with the same frequency and simultaneous detection. During the measurement process, the mixer is used to reduce the frequency, so there will be a DC level offset (dc offset) problem, causing the receiver to be flooded with a strong DC signal, causing saturation and making the signal undetectable. If it can be solved, it will be easier to achieve the effect of stable detection.

Contents of the invention

The purpose of the present invention is to provide a microwave motion detector, the detection effect is more stable, it is not easy to cause poor reception and uninterpretable results due to changes in the external environment, and can effectively solve the problem of dynamic range saturation of traditional radar receivers.

According to an exemplary embodiment of the present invention, a microwave motion detector is proposed, including: a transmitting device, which transmits a microwave signal to the space to be tested; a receiving device, which receives the reflected microwave signal reflected by the space to be tested; signal processing A device for processing the reflected microwave signal received by the receiving device to determine whether there is disturbance in the space to be measured, the signal processing device generating the microwave signal; and a path switching device coupled to the signal processing device and the transmitting device , the path switching device makes the multiple transmitting paths passed by the microwave signal have different phase shifts.

According to another exemplary embodiment of the present invention, a microwave motion detector is proposed, including: a transmitting device, which transmits a microwave signal to the space to be tested; a receiving device, which receives the reflected microwave signal reflected by the space to be tested; a switching device, coupled to the receiving device, the path switching device makes the multiple receiving paths passed by the reflected microwave signal have different phase shifts; and a signal processing device, processing the reflected microwave signal received by the receiving device, to To judge whether there is disturbance in the space to be measured, the signal processing device generates the microwave signal.

According to a further exemplary embodiment of the present invention, a microwave motion detector is proposed, including: a transceiver device, which transmits a microwave signal to the space to be tested, and receives a reflected microwave signal reflected by the space to be tested; a signal processing device processing the reflected microwave signal received by the transceiver device to determine whether there is disturbance in the space to be measured, the signal processing device generating the microwave signal; and a path switching device coupled to the signal processing device and the transceiver device, The path switching device makes the microwave signal and the multiple paths passed by the reflected microwave signal have different phase shifts.

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments, but not as a limitation of the present invention.

Description of drawings

Fig. 1 shows the sensing sensitivity change curve of the traditional microwave motion detector;

Figure 2 shows a functional block diagram of a microwave motion detector according to an embodiment of the present invention;

FIG. 3A shows an exemplary example of a delay path switching unit according to an embodiment of the present invention;

FIG. 3B shows a schematic diagram of changes in sensing sensitivity according to an embodiment of the present invention;

FIG. 4A and FIG. 4B show a sequence diagram of path switching control according to this embodiment;

FIG. 5A and FIG. 5B respectively show functional block diagrams of microwave motion detectors according to other embodiments of the present invention.

Among them, reference signs

100, 300: detector 110, 310: object to be tested

200, 500A, 500B: Microwave Motion Detector

210: Transmit Antenna

220, 520A, 520B: delay path switching unit

225: Phase-locked loop (signal processing device)

230: Phase/frequency detection unit

240: Charge pump 250: Low-pass filter

260: Double-ended control voltage-controlled oscillator

270: Receiving antenna 280: Path switching controller

P1, P2: Path 510: Antenna

Detailed ways

Below in conjunction with accompanying drawing, structural principle and working principle of the present invention are specifically described:

Embodiments of the present invention propose a microwave-based motion detector architecture, which uses the Doppler principle. In the embodiment of the present invention, when the high-sensitivity self-injection-locked voltage-controlled oscillator receives the Doppler phase modulation signal reflected back from the object under test, it will generate a corresponding output phase or frequency disturbance. Use the phase-locked loop to lock the output frequency of the injection-locked voltage-controlled oscillator, so that the external (due object) disturbance information can be reflected to the control terminal voltage of the injection-locked voltage-controlled oscillator, and the output frequency can be fixed to reduce bandwidth requirements and electromagnetic interference. .

In the embodiment of the present invention, the transmission/reception paths with different phase shifts are switched so that the sensing zero positions of these transmission/reception paths do not overlap (or even the sensing zero positions of these transmission/reception paths are interleaved), so as to eliminate single-frequency interference. Sensing null phenomenon of Pleur radar. The sensing sensitivities of these transmission/reception paths have complementary benefits, that is, if one of the paths is at the sensing zero point, the other paths will not be at the sensing zero point, so the disturbance of the DUT can be detected stably.

In the embodiments of the present invention, when detecting low-frequency action/disturbance signals, the transmission signal path can be closed during the non-sampling point period, and the average microwave transmission power can be reduced in principle.

The embodiment of the present invention utilizes a double-terminal controlled voltage controlled oscillator to adjust the DC level, so as to eliminate the DC level offset. The physical principle is to add another voltage control port and another variable voltage capacitor. The resonant frequency of the resonant cavity of the oscillator is changed, and the DC level of the output signal of the phase-locked self-injection-locked double-terminal control voltage-controlled oscillator is adjusted back to the original set value.

FIG. 2 shows a functional block diagram of a microwave motion detector according to an embodiment of the present invention. As shown in FIG. 2 , the microwave motion detector 200 includes: at least one transmitting antenna 210 , a delay path switching unit 220 , a phase-locked loop 225 and at least one receiving antenna 270 . The phase-locked loop 225 includes: a phase/frequency detection unit (Phase Frequency Detector, PFD) 230, a charge pump (Charge Pump, CP) 240, a low-pass filter (Low Pass Filter, LPF) 250 and a double-terminal control voltage-controlled oscillator 260. In this embodiment, the phase locked loop can also be called a signal processing device. The microwave motion detector 200 may also optionally include a path switching controller 280 .

The transmitting antenna 210 is used to transmit the microwave signal, and the receiving antenna 270 is used to receive the microwave signal reflected by the object under test.

The delay path switching unit 220 is used for switching different delay paths so that the multiple paths have different phase shifts (that is, the multiple paths have phase differences between each other). In this way, different delay paths can be selected as signal transmission paths. In the following, switching between two different delay paths is taken as an example for illustration, but it should be understood that the present case is not limited thereto. In this case, multiple paths with different delays can also be formed and switched among these paths with different delays.

Please refer to FIG. 3A , which shows an exemplary example of the delay path switching unit 220 according to an embodiment of the present invention. As shown in FIG. 3A , the delay path switching unit 220 includes: a delay unit D, switches SW1 and SW2 . The switches SW1 and SW2 are, for example but not limited to, single pole double throw (SPDT, Single Pole Double Throw) switches. The delay unit D delays the phase of the signal by, for example, 90 degrees. That is, the phase difference between the paths P1 and P2 is, for example, 90 degrees.

Please refer to FIG. 3B , which shows a schematic diagram of changes in sensing sensitivity according to an embodiment of the present invention, the horizontal axis is the distance, and the vertical axis is the sensing sensitivity. It can be seen from FIG. 3B that since there are two different delay paths, the positions of the sensing zeros of the two paths are different from each other. Therefore, the disadvantage of the prior art that the detector cannot detect the object under test due to the zero point sensing can be solved in the embodiment of the present invention. In detail, if the object under test 310 is located at the sensing zero point on one path of the detector 300 , the object under test 310 will not be located at the sensing zero point on the other path.

Please return to Figure 2 now. The PLL 225 controls the VCO 260 . The PLL 225 can also be called a signal processing device. The details of the PLL 225 are as follows. The phase/frequency detection unit 230 is used for detecting the phase difference (or frequency difference) between the output signal of the double-terminal controlled voltage controlled oscillator 260 and the output of the reference signal REF.

The charge pump 240 outputs a voltage signal according to the detection result of the phase/frequency detection unit 230 . The output voltage signal of the charge pump 240 is filtered by the low-pass filter 250 to become the first control voltage VCO_CN1. The first control voltage VCO_CN1 is used to control the frequency of the output signal of the double-terminal controlled voltage-controlled oscillator 260 .

The double-ended control VCO 260 is an injection-locked VCO architecture. The double-terminal controlled voltage-controlled oscillator 260 can simultaneously output signals and inject (ie receive) signals. In other possible embodiments, the output signal of the double-terminal controlled VCO 260 may be connected to the input of the delay path switching unit 220 and the input of the PLL 225 through a power splitter (not shown). The output microwave signal of the dual-terminal controlled voltage-controlled oscillator 260 passes through the delay path switching unit 220 , and then is transmitted to the object under test/space under test by the transmitting antenna 210 .

If there is a disturbance signal in the space to be measured (this disturbance is such as human heartbeat, human respiration, window oscillation, etc.), when the transmitted signal is reflected, due to the Doppler effect, the phase or frequency of the reflected signal will change (compared to the transmitted signal). Signal). The reflected signal is received by the receiving antenna 270 , and can be amplified (the amplifier is not shown) and injected into the dual-terminal controlled voltage-controlled oscillator 260 . The double-terminal controlled voltage-controlled oscillator 260 changes the phase or frequency of its output signal due to the influence of the reflected signal. After the phase or frequency change of the output signal of the double-terminal control voltage-controlled oscillator 260 enters the phase-locked loop 225, the phase-locked loop 225 will generate a corresponding first control voltage VCO_CN1 for the phase or frequency change to correct the double-terminal control voltage. The output frequency of the controlled oscillator 260 returns to the reference frequency. The external disturbance information can be obtained by observing the first control voltage VCO_CN1.

In addition, in this embodiment, the second control voltage VCO_CN2 of the double-terminal controlled voltage-controlled oscillator 260 can be used to eliminate its DC level offset. The oscillation frequency of the double-terminal controlled voltage-controlled oscillator 260 is determined by two control voltages VCO_CN1 and VCO_CN2 . If the double-terminal controlled voltage-controlled oscillator 260 is affected by the external disturbance signal and causes the main first control voltage VCO_CN1 to produce a DC level shift, according to the physical principle, the following equation (1) can be listed to calculate the second required change. The control voltage VCO_CN2 is used to eliminate the DC level offset of the first control voltage VCO_CN1. Among them, Kv1 and Kv2 are system constants, which can be determined by the designer.

Kv1*△VCO_CN1+Kv2*△VCO_CN2=0 (1)

Wherein, ΔVCO_CN1 and ΔVCO_CN2 respectively represent the voltage variation of the first and second control voltages VCO_CN1 and VCO_CN2 .

From the above formula (1), it can be deduced that:

$\mathrm{<span\; class="notranslate">\; \&Delta;\; VCO</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="CN"\; filenames="HDA00002464705800023.png"\; state="\{\{state\}\}">CN</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; V</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}\mathrm{<span\; class="notranslate">\; \&Delta;\; VCO</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; CN</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; V</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

If it is detected that the DC average value of the main first control voltage VCO_CN1 changes, the required variation of the second control voltage VCO_CN2 can be obtained according to the above equations (1) and (2). For example but not limited to, the constant Kv1 is 2MHz/V and the constant Kv2 is 20MHz/V. If the system detects that the DC average value of the main first control voltage VCO_CN1 changes to 1V, the variation of the second control voltage VCO_CN2 can be obtained as −0.1V according to the above equations (1) and (2). That is, the DC level offset of the first control voltage VCO_CN1 can be eliminated by reducing the second control voltage VCO_CN2 by 0.1V. That is to say, the DC level offset of the external disturbance information represented by the first control voltage VCO_CN1 has been eliminated.

In practice, the double-terminal controlled VCO 260 can be realized by adding a voltage control port and a variable capacitor (varactor) to the traditional VCO. Changing the resonant frequency of the resonant cavity allows the DC level of the first control voltage used to control the phase-locked self-injection-locked oscillator (double-terminal controlled voltage-controlled oscillator 260 ) to be adjusted back to the original set value. Therefore, there is no need to add additional complicated control loops and radio frequency components. Applying this method can effectively solve the problem of saturation of the dynamic range of traditional radar receivers (caused by DC level offset), making the detection effect of the microwave detector more stable, and it is not easy to cause poor reception due to changes in the external environment and cannot be interpreted the result of.

Please refer to FIG. 4A and FIG. 4B , which show a sequence diagram of path switching control according to this embodiment. In FIG. 4A , the paths P1 and P2 are switched, so that the sensing signals of the two paths P1 and P2 can be time-divisionally received/transmitted, so as to avoid the sensing zero point problem due to the paths.

In addition, if the disturbance of the detected object is a slow low-frequency signal (for example, human heartbeat/respiration is about 72 beats/minute, which is about 1.2 Hz), the embodiment of the present invention can also reduce the transmission power. As shown in FIG. 4B , for example but not limited to, the transmission time of paths P1 and P2 is about 1 ms. If the non-transmission period (during the non-transmission period, no microwave signal is emitted) is about 48 ms, the average frequency is 20 Hz, which is much higher than the disturbance frequency of the object to be measured. It can be seen that, in this embodiment, the transmit path can be turned off outside the respective sampling times of the two paths, so as to reduce the average transmit power without compromising the detection sensitivity. The switching sequence of FIG. 4A and FIG. 4B can be controlled by the path switching controller (as shown in FIG. 2 ). The path switching controller can send out a plurality of switch control signals to control a plurality of switches in the delay path switching unit.

FIG. 5A and FIG. 5B respectively show functional block diagrams of microwave motion detectors according to other embodiments of the present invention. Comparing FIG. 5A with FIG. 2 , it can be seen that in the microwave motion detector 500A in FIG. 5A , the delay path switching unit 520A is used to switch between different delay paths on the receiving path. Comparing FIG. 5B with FIG. 2, it can be seen that in the microwave motion detector 500B in FIG. 5B, its single antenna 510 is used to receive and transmit microwave signals at the same time, but different from FIG. 2, the delay path switching unit 520B in FIG. The switching path phase shift is, for example, 45 degrees.

In addition, those skilled in the art should know that the above-mentioned embodiments of the present application can be combined arbitrarily, and all of them are within the scope of the spirit of the present application. For example, in yet another possible embodiment of the present application, a delay path switch unit may be provided on both the transmit path and the receive path to switch the transmit path and the receive path respectively. The details can be obtained from the above discussion and will not be repeated here.

Embodiments of the present invention may be applicable to detect, such as but not limited to, human respiration, human heartbeat, disturbance, vibration (such as window vibration), and the like.

In addition, although the embodiment of the present invention proposes switching the path delay method to cooperate with the self-injection locking Doppler radar, the switching path delay method of the embodiment of the present invention can also be applied to other single-frequency Doppler radar architectures.

As can be seen from the above, the above-mentioned multiple embodiments of the present invention have at least the following advantages:

In the embodiment of the present invention, in order to solve the problem of sensing zero point (that is, external disturbances cannot be sensed at some positions), the sensing of these transmission/reception paths is made by switching transmission/reception paths with different phase shifts. The null positions do not overlap (or even stagger the sensing null positions of these transmit/receive paths). In this way, the object under test has good sensing sensitivity in almost every position to eliminate the sensing zero point phenomenon. That is, the sensing sensitivities of these transmit/receive paths can be complementary.

In addition, if a low-frequency action/disturbance signal is detected, the embodiment of the present invention may utilize a lower sampling frequency and still be sufficient to detect the disturbance. Even, there is no need to transmit radio waves to the outside during the non-sampling point period, which can further effectively reduce the average transmission power, and in actual use, reduce the concern that microwaves will cause damage to human body safety.

The embodiment of the present invention utilizes a double-terminal controlled voltage-controlled oscillator to adjust the DC level, so as to eliminate the DC level offset, and does not need to add additional complicated control loops and radio frequency components. The detection effect of the microwave detector in the embodiment of the present invention is more stable, and it is not easy to cause poor reception and uninterpretable results due to changes in the external environment. The embodiment of the present invention can effectively solve the problem of saturation of the dynamic range of the traditional radar receiver.

Of course, the present invention can also have other various embodiments, and those skilled in the art can make various corresponding changes and deformations according to the present invention without departing from the spirit and essence of the present invention, but these corresponding Changes and deformations should belong to the scope of protection of the appended claims of the present invention.

Claims (14)

1. a microwave motion detecting device, is characterized in that, comprising:

Emitter, launched microwave signal is to space to be measured;

Receiving trap, receives the reflected microwave signal being reflected back by this space to be measured;

Signal processing apparatus, processes this reflected microwave signal that this receiving trap receives, and to judge in this space to be measured whether have disturbance, this signal processing apparatus produces this microwave signal; And

Path switching device, is coupled to this signal processing apparatus and this emitter, this path switching device make this microwave signal multiple transmission paths of process there is different phase shift.

2. microwave motion detecting device according to claim 1, is characterized in that, multiple sensings of those transmission paths do not overlap each other zero point.

3. microwave motion detecting device according to claim 1, is characterized in that, also comprises path switch controller, is coupled to this path switching device, to select one of those transmission paths.

4. microwave motion detecting device according to claim 3, is characterized in that, this path switch controller is closed those transmission paths at part-time.

5. microwave motion detecting device according to claim 1, is characterized in that,

This signal processing apparatus at least comprises double-ended control voltage controlled oscillator, produces this microwave signal;

Relatively this microwave signal and reference signal are to obtain the first control voltage for this signal processing apparatus, and this first controls the external disturbance information that voltage reflects this space to be measured;

The concussion frequency of this double-ended control voltage controlled oscillator is controlled voltage by this first control voltage and second and is determined; And

If being subject to this external disturbance informational influence, this double-ended control voltage controlled oscillator make this first control voltage produce the accurate skew in direct current position, this signal processing apparatus produces the second voltage variable quantity of this second control voltage according to this first first voltage variety of controlling voltage, eliminate this first direct current position standard of controlling voltage and be offset.

6. a microwave motion detecting device, is characterized in that, comprising:

Emitter, launched microwave signal is to space to be measured;

Receiving trap, receives the reflected microwave signal being reflected back by this space to be measured;

Path switching device, is coupled to this receiving trap, this path switching device make this reflected microwave signal multiple RX path of process there is different phase shift; And

Signal processing apparatus, processes this reflected microwave signal that this receiving trap receives, and to judge in this space to be measured whether have disturbance, this signal processing apparatus produces this microwave signal.

7. microwave motion detecting device according to claim 6, is characterized in that, multiple sensings of those RX path do not overlap each other zero point.

8. microwave motion detecting device according to claim 6, is characterized in that, also comprises path switch controller, is coupled to this path switching device, to select one of those RX path.

9. microwave motion detecting device according to claim 6, is characterized in that,

This signal processing apparatus at least comprises double-ended control voltage controlled oscillator, produces this microwave signal;

Relatively this microwave signal and reference signal are to obtain the first control voltage for this signal processing apparatus, and this first controls the external disturbance information that voltage reflects this space to be measured;

The concussion frequency of this double-ended control voltage controlled oscillator is controlled voltage by this first control voltage and second and is determined; And

If being subject to this external disturbance informational influence, this double-ended control voltage controlled oscillator make this first control voltage produce the accurate skew in direct current position, this signal processing apparatus produces the second voltage variable quantity of this second control voltage according to this first first voltage variety of controlling voltage, eliminate this first direct current position standard of controlling voltage and be offset.

10. a microwave motion detecting device, is characterized in that, comprising:

R-T unit, launched microwave signal is space to be measured extremely, and receives the reflected microwave signal being reflected back by this space to be measured;

Signal processing apparatus, processes this reflected microwave signal that this R-T unit receives, and to judge in this space to be measured whether have disturbance, this signal processing apparatus produces this microwave signal; And

Path switching device, is coupled to this signal processing apparatus and this R-T unit, this path switching device make this microwave signal and this reflected microwave signal multiple paths of process there is different phase shift.

11. microwave motion detecting devices according to claim 10, is characterized in that, multiple sensings in those paths do not overlap each other zero point.

12. microwave motion detecting devices according to claim 10, is characterized in that, also comprise path switch controller, are coupled to this path switching device, to select one of those paths.

13. microwave motion detecting devices according to claim 12, is characterized in that, this path switch controller is closed those paths at part-time.

14. microwave motion detecting devices according to claim 10, is characterized in that,

This signal processing apparatus at least comprises double-ended control voltage controlled oscillator, produces this microwave signal;

Relatively this microwave signal and reference signal are to obtain the first control voltage for this signal processing apparatus, and this first controls the external disturbance information that voltage reflects this space to be measured;

The concussion frequency of this double-ended control voltage controlled oscillator is controlled voltage by this first control voltage and second and is determined; And

If being subject to this external disturbance informational influence, this double-ended control voltage controlled oscillator make this first control voltage produce the accurate skew in direct current position, this signal processing apparatus produces the second voltage variable quantity of this second control voltage according to this first first voltage variety of controlling voltage, eliminate this first direct current position standard of controlling voltage and be offset.

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