CN115508856A - Target object detection method based on microwave photon radar and active phase modulation RFID device - Google Patents

Target object detection method based on microwave photon radar and active phase modulation RFID device Download PDF

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CN115508856A
CN115508856A CN202211228425.9A CN202211228425A CN115508856A CN 115508856 A CN115508856 A CN 115508856A CN 202211228425 A CN202211228425 A CN 202211228425A CN 115508856 A CN115508856 A CN 115508856A
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active phase
phase modulation
rfid device
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李广
何飞勇
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Guangdong Institute of Science and Technology
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/88—Lidar systems specially adapted for specific applications
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/88—Lidar systems specially adapted for specific applications
    • G01S17/93—Lidar systems specially adapted for specific applications for anti-collision purposes
    • G01S17/931—Lidar systems specially adapted for specific applications for anti-collision purposes of land vehicles
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/88—Lidar systems specially adapted for specific applications
    • G01S17/93—Lidar systems specially adapted for specific applications for anti-collision purposes
    • G01S17/933—Lidar systems specially adapted for specific applications for anti-collision purposes of aircraft or spacecraft
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/28—Details of pulse systems
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K19/00—Record carriers for use with machines and with at least a part designed to carry digital markings
    • G06K19/06—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code
    • G06K19/067—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components
    • G06K19/07—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components with integrated circuit chips
    • G06K19/077—Constructional details, e.g. mounting of circuits in the carrier
    • G06K19/07749—Constructional details, e.g. mounting of circuits in the carrier the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card

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Abstract

The invention provides a target object detection method based on a microwave photon radar and an active phase modulation RFID device, which comprises the steps that a microwave photon radar system emits a leaky wave emission signal; after an antenna of the active phase modulation RFID device arranged on a target object receives a leakage wave transmitting signal, the active phase modulation RFID device controls the change of the on-off state of a switch device, the reflection coefficient of the active phase modulation RFID device is enabled to be 1 when the switch device is switched on, the reflection coefficient of the active phase modulation RFID device is enabled to be-1 when the switch device is switched off, and the active phase modulation RFID device reflects the leakage wave transmitting signal to form a leakage wave receiving signal; and the microwave photon radar system receives the leakage wave receiving signal reflected by the active modulation RFID device and calculates the position of the target object by applying the receiving leakage wave signal. The invention can improve the modulation coefficient of the feedback signal received by the microwave photon radar system, thereby improving the power of the leakage wave receiving signal and improving the detection accuracy.

Description

Target object detection method based on microwave photon radar and active phase modulation RFID device
Technical Field
The invention relates to the technical field of object detection, in particular to a target object detection method based on a microwave photon radar and an active phase modulation RFID device.
Background
With the development of detection technology, the detection of moving objects has been widely applied in many fields, for example, radar systems are used to detect moving automobiles, airplanes, etc. to determine the positions and moving directions of the automobiles, airplanes, etc. so as to determine whether the automobiles have illegal behaviors or whether the flying objects fly according to a specified channel.
In the conventional method for detecting a moving object, a radar system generally transmits a signal for detection, generally a high-frequency radio signal, when the detection signal encounters the moving object, the moving object reflects the detection signal, and the radar system receives the reflected signal, calculates a distance between a target object and the radar system according to the transmitted signal and the reflected signal, and calculates a moving direction of the target object.
However, since the signals reflected by the target object are usually very weak, the radar system can easily filter out the weak signals as interference signals, so that the radar system cannot accurately detect the moving object. Some existing moving objects are provided with RFID devices, detection signals transmitted by a radar system are reflected by the RFID devices, and the intensity of the reflected signals received by the radar system is increased in such a way, so that the accuracy of detecting the moving objects is improved.
The chinese patent application with publication number CN101436261A discloses a 2.45GHz semi-active radio frequency identification tag, which is provided with two dipole antennas, a load modulation module and a two-way selection module, wherein the two-way selection module is provided with two switches, and one of the switches can control the connection between the load modulation module and one of the dipole antennas. The connection state between the dipole antennas and the load modulation module can be changed by controlling the on-off state change of the switch, so that the reflection coefficient of the radio frequency identification tag is changed. For example, when the switch is turned off, the load modulation module and the dipole antenna are in an off state, the load modulation module is not electrified, the radio-frequency signal received by the antenna module is totally reflected by the antenna module, and the reflection coefficient is-1 at this time; when the switch is closed, the load modulation module and the dipole antenna are in an electric communication state, the load modulation module is electrified, the radio-frequency signals received by the antenna module are received by the load modulation module, no radio-frequency signals are emitted out through the antenna module, and the reflection coefficient at the moment is 0.
In general, the microwave photonic radar receives the received power P of the reflected signal from the RFID device r Can be calculated by the following formula:
Figure BDA0003881062320000021
wherein P is t Is the signal transmission power, G, of the radar system r Is the reception gain, G, of the radar system t Is the transmit gain of the radar system, X is the degree of polarization mismatch, λ is the wavelength of the transmitted signal, r is the distance between the antenna and the target object, M is the modulation factor, B is the path blocking loss, F a Is the fade margin. Therefore, in order to increase the received power P r Should increase the transmission power P t Reception gain G r Emission gain G t And modulation factor M, and reducing path blocking loss B and attenuation margin F a . However, due to the power limitations of the radar system, the transmission power P t Are often limited. Transmission gain G r And a reception gain G t This can be increased by mounting a directional antenna on the radar, but increases the production cost of the radar system. In practice, the received power P can be increased by increasing the modulation factor M in consideration of r . The modulation factor M can be calculated by the following formula:
Figure BDA0003881062320000022
wherein, gamma is A And Γ B Respectively, the reflection coefficient of the RFID device in the two states. Since the reflection coefficients of the RFID device are-1 and 0, respectively, in the prior art, the modulation coefficient M has a value of 1/4. Due to modulation factor MThe value is small, which affects the power of the reflected signal received by the radar system and the accuracy of the detection of the moving object.
Disclosure of Invention
The invention aims to provide a target object detection method based on a microwave photon radar and an active phase modulation RFID device, which can improve the power of a radar system receiving signal.
In order to achieve the above object, the method for detecting a target object based on a microwave photonic radar and an active phase modulation RFID device according to the present invention includes: a microwave photon radar system transmits a leaky wave transmitting signal; after an antenna of the active phase modulation RFID device arranged on a target object receives a leakage wave transmitting signal, the active phase modulation RFID device controls the change of the on-off state of a switch device, the reflection coefficient of the active phase modulation RFID device is enabled to be 1 when the switch device is switched on, the reflection coefficient of the active phase modulation RFID device is enabled to be-1 when the switch device is switched off, and the active phase modulation RFID device reflects the leakage wave transmitting signal to form a leakage wave receiving signal; and the microwave photon radar system receives the leakage wave receiving signal reflected by the active modulation RFID device and calculates the position of the target object by applying the receiving leakage wave signal.
According to the scheme, the reflection coefficients of the active phase modulation RFID device are 1 and-1 respectively under the two states of the on state and the off state of the switching device, and the modulation coefficient M is 1 according to the formula 2. After the radar system receives the high-power reflected signal, the position of the target object can be calculated more accurately, and the phenomenon that the received reflected signal is mistaken for an interference signal and is filtered mistakenly due to the fact that the power of the received reflected signal is too small is avoided.
One preferred scheme is that when the active phase modulation RFID device receives a leakage wave emission signal, the change of the conducting state of the switching device is controlled; and when the active phase modulation RFID device does not receive the leakage wave emission signal, stopping controlling the change of the conduction state of the switching device.
Therefore, the on-off state change of the switching device is controlled only when the active phase modulation RFID device receives the leakage wave emission signal, namely the switching device is driven to act. When the leakage wave emission signal is not received, the driving of the switching device is stopped, on one hand, the switching device can be prevented from being in a working state for a long time, the service life of the switching device is prolonged, and on the other hand, high loss caused by the fact that the switching device is driven to act for a long time can be avoided.
The active phase modulation RFID device is further provided with a low-frequency signal generating circuit, and the low-frequency signal generating circuit is used for outputting a low-frequency signal to the switching device so as to control the change of the on-off state of the switching device.
Therefore, the low-frequency signal generating circuit is arranged to output the low-frequency signal to control the switch device to work, the switch device is ensured to work in a low-frequency state, and accurate switching of the reflection coefficient of the active phase modulation RFID device is further ensured.
The active phase modulation RFID device receives the leakage wave emission signal, and the low-frequency signal generating circuit outputs a low-frequency signal to the switching device; when the active phase modulation RFID device does not receive the leakage wave emission signal, the low-frequency signal generating circuit stops outputting the low-frequency signal to the switching device.
The switch device is a diode, the anode end of the diode receives a low-frequency signal, the low-frequency signal is a low-frequency pulse signal, the diode is conducted when the low-frequency pulse signal is at a high level, and the diode is cut off when the low-frequency pulse signal is at a low level.
The diode is used as a switching device, so that the active phase modulation RFID device is simple in structure and low in generation cost. And the performance of the diode is stable, and the long-time operation of the switching device can be ensured.
In a further aspect, an active phase modulation RFID device includes an inductor connected between a low frequency signal generating circuit and a switching device, and a low frequency signal is output to the switching device through the inductor.
Since the inductor allows low frequency signals to pass through and high frequency signals cannot pass through the inductor, level signals can be ensured to pass through the inductor and control the operation of the switching device by arranging the inductor, and high frequency signals received by the antenna cannot pass through the inductor and ensure that the high frequency signals cannot influence the operation of the switching device.
The active phase modulation RFID device comprises an antenna and a load resistor, wherein the antenna and the load resistor are sequentially connected with a switch device, one end of the switch device is connected to the load resistor, and the second end of the switch device is grounded.
Further, when the switching device is conducted, the antenna is short-circuited to the ground, so that the reflection coefficient of the active phase modulation RFID device is 1; when the switching device is turned off, the antenna is opened, so that the reflection coefficient of the active phase modulation RFID device is-1.
Therefore, when the switching device is turned on, the load resistor is directly grounded, which is equivalent to that the antenna is directly grounded, and the antenna is not matched with the load, so that the reflection coefficient of the active phase modulation RFID device is 1. When the switching device is turned off, the antenna and the load resistor are not formed back, no current flows through the load resistor, the signals received by the active phase modulation RFID device are totally reflected, and the reflection coefficient is-1. Since the reflection coefficient of the active phase modulated RFID device switches between 1 and-1, it is equivalent to forming a signal that is in phase opposition.
According to a further scheme, after the microwave photon radar system receives the leaky wave receiving signal, the position of the target object is calculated according to the time difference between the emission time of the leaky wave emission signal and the receiving time of the leaky wave receiving signal.
Therefore, when the position of the target object is calculated, only the time difference between the emission time of the leaky wave emission signal and the receiving time of the leaky wave receiving signal and the wavelength of the leaky wave emission signal need to be acquired, the calculation of the distance of the target object is very simple, the very complicated calculation is not needed, and the detection efficiency can be improved.
According to a further scheme, after the microwave photon radar system receives the leaky wave receiving signal, the moving direction of the target object is calculated according to the frequency difference between the leaky wave transmitting signal and the leaky wave receiving signal.
Therefore, the moving direction of the target object can be rapidly calculated by applying the Doppler efficiency, and the calculation is very simple.
Drawings
Fig. 1 is a block diagram of the structures of a microwave photonic radar system and an active phase modulation RFID device used in an embodiment of a target object detection method based on a microwave photonic radar and an active phase modulation RFID device according to the present invention.
FIG. 2 is a flowchart of an embodiment of a target object detection method based on a microwave photonic radar and an active phase modulation RFID device according to the present invention.
Fig. 3 is a flowchart of calculating the position and moving direction of a target object according to an embodiment of the target object detection method based on the microwave photonic radar and the active phase modulation RFID device.
The invention is further explained with reference to the drawings and the embodiments.
Detailed Description
The target object detection method based on the microwave photonic radar and the active phase modulation RFID device adopts the microwave photonic radar to transmit signals, the active phase modulation RFID device is arranged on the target object, the received signals are reflected by the active phase modulation RFID device, and the position, the moving direction and even the moving speed of the target object are calculated by the reflected signals. Preferably, the target object is an object moving at a high speed, and may be, for example, an airplane, an automobile, or the like.
Referring to fig. 2, the microwave photonic radar system used in the present invention includes a leaky-wave transmitting antenna 11 and a leaky-wave receiving antenna 12, where the leaky-wave transmitting antenna 11 is used to transmit a leaky-wave transmitting signal, and preferably, the leaky-wave transmitting signal 11 is a high-frequency radio signal, such as a 24GHz radio signal. When the leaky-wave transmitting signal meets the target object to be detected, the leaky-wave transmitting signal is reflected by the target object to form a leaky-wave receiving signal, and the leaky-wave receiving antenna 12 receives the leaky-wave receiving signal. The microwave photonic radar system 10 may further include a processor for calculating parameters such as a position, a moving direction, and a moving speed of the target object according to the leakage wave transmitting signal and the leakage wave receiving signal. Of course, the microwave photonic radar system 10 may further include a signal amplifier, a filter, and other devices for performing signal amplification, filtering, and other processing on the received leaky wave receiving signal, particularly removing a total low-frequency signal of the received signal, so as to ensure accuracy of the calculation result.
In practical applications, the leaky-wave transmitting antenna 11 and the leaky-wave receiving antenna 12 of the microwave photonic radar system 10 may be integrated in the same antenna module, or implemented by the same antenna, that is, the same antenna is used to transmit a leaky-wave transmitting signal and receive a leaky-wave receiving signal.
The active phase-modulated RFID device 20 used in this embodiment includes an antenna 21, a load resistor R1, an inductor L1, a diode D1 serving as a switching device, and a filter capacitor C1, and is further provided with a low-frequency signal source 25 and a schmitt trigger 26, where the low-frequency signal source 25 and the schmitt trigger 26 form a low-frequency signal generating circuit for generating a low-frequency signal.
The low frequency signal source 25 is a signal source for generating a low frequency sine wave, for example, implemented using an oscillator circuit, and the frequency of the generated low frequency sine wave signal may be 1kHz. The frequency of the low-frequency sine wave signal is very low compared to the frequency of the leaky wave transmission signal, and thus becomes a low-frequency sine wave signal. The schmitt trigger 26 receives the low-frequency sinusoidal signal output from the low-frequency signal source 25 and shapes the low-frequency sinusoidal information to form a low-frequency pulse signal. In an ideal situation, the duty cycle of the low frequency pulse signal is 50%, i.e. the duration of the high level is equal to the duration of the low level. Since the frequency of the low-frequency sine wave signal is not changed by the schmitt trigger 26, the frequency of the low-frequency pulse signal is equal to the frequency of the low-frequency sine wave signal. In this embodiment, the low-frequency signal output by the low-frequency signal generation circuit is the low-frequency pulse signal output by the schmitt trigger 26.
The antenna 21 is used for receiving the leaky-wave receiving signal transmitted by the leaky-wave transmitting antenna 11, and can reflect the received leaky-wave transmitting signal back to form a leaky-wave receiving signal. The antenna 21 is connected to a first end of the load resistor R1, a second end of the load resistor R1 is connected to the diode D1, an anode end of the diode D1 is connected to the load resistor R1, and a cathode end is grounded.
An inductor L1 is connected between the schmitt trigger 26 and the anode terminal of the diode D1, and one end of the inductor L1 is connected between the anode of the diode D1 and the load resistor R1, so that the low-frequency pulse signal output from the schmitt trigger 26 is output to the anode terminal of the diode D1 through the inductor L1. In this embodiment, the diode is a PIN diode, and the conduction voltage drop of the PIN diode is usually about 0.7 v. In order to drive the diode D1 to change its on-off state, the high level and the low level of the low-frequency pulse signal output by the schmitt trigger 26 should be respectively higher and lower than the conduction voltage drop of the diode D1. For example, the high level of the low frequency pulse signal may be 3 volts, and the low level may be 0.2 volts, so that when the low frequency pulse signal is high, the diode D1 is forward biased and in a conducting state, and when the low frequency pulse signal is low, the diode D1 is not conducting, i.e., in a blocking state.
As can be seen from fig. 1, when the diode D1 is in a conducting state, the antenna 21, the load resistor R1, and the diode D1 form a loop, and since the load resistor R1 is actually grounded, the load resistor R1 corresponds to a short circuit to ground, that is, the antenna 21 is also short-circuited to ground, and it can be considered that the load resistor connected to the antenna 21 is infinite at this time. The reflection coefficient Γ of the active phase modulated RFID device 20 may be calculated using the following equation:
Figure BDA0003881062320000071
wherein Z is L Is an input impedance, Z, in a circuit connected to the antenna 21 * ANT Is the input impedance of the antenna 21. When the diode D1 is in the on state, the load resistor R1 is grounded, and therefore, the input impedance Z is set in a circuit forming a loop with the antenna 21 L Can be considered infinite and the input impedance Z of the antenna 21 is * ANT Usually several tens of ohms, and therefore the input impedance Z of the antenna 21 can be understood * ANT Much smaller than the input impedance Z L Therefore, according to equation 3, when the diode D1 is in the on state, the reflection coefficient Γ of the active phase modulation RFID device 20 is 1.
When the diode D1 is in the off state, a loop cannot be formed between the antenna 21, the load resistor R1, and the diode D1. Since the inductor L1 does not allow a high-frequency signal to pass therethrough, the antenna 21 receives a high-frequency leakage wave transmission signalThe signal cannot pass through the inductor L1, and a loop cannot be formed. Thus, the load resistor R1 does not have a current flowing therethrough, and it can be considered that the input impedance Z in the circuit connected to the antenna 21 is input L Is 0. According to equation 3, when the diode D1 is in the off state, the reflection coefficient Γ of the active phase modulation RFID device 20 is-1.
It can be seen that when the on-off state of the diode D1 changes, the reflection coefficient Γ of the active phase modulation RFID apparatus 20 changes back and forth between 1 and-1, and according to equation 2, the modulation coefficient M of the active phase modulation RFID apparatus 20 is 1, and compared with the conventional RFID apparatus, the modulation coefficient M of the active phase modulation RFID apparatus 20 used in the present embodiment is four times that of the conventional RFID apparatus. According to equation 1, the power of the reflected signal received by the leaky-wave receiving antenna 12 of the microwave photonic radar system 20 will be greatly increased, thereby improving the accuracy of the subsequent calculation. In addition, because the power of the reflected signal received by the leaky-wave receiving antenna 12 is large, the amplification factor of the microwave photonic radar system 20 on the received leaky-wave received signal can be reduced, which is beneficial to reducing the complexity of the microwave photonic radar system 20 and reducing the production cost of the microwave photonic radar system 20.
In the active phase modulation RFID device 20, a filter capacitor C1 is further connected between the output terminal of the schmitt trigger 26 and the inductor L1, one end of the filter capacitor C1 is connected to the inductor L1, and the other end is grounded. The filter capacitor C1 can filter out an interference signal of the low-frequency pulse signal output by the schmitt trigger 26, so that the waveform of the low-frequency pulse signal input to the diode D1 is more regular.
It can be understood that, since the reflection coefficients of the leakage wave receiving signals of the active phase modulation RFID device 20 are 1 and-1, respectively, the active phase modulation RFID device 20 performs Binary Phase Modulation (BPM) on the received leakage wave transmitting signals, and the phase difference of 180 ° is formed between the reflected leakage wave receiving signals in the two states. Suppose that the leakage received signal M is in the first state 1 (t) is expressed by the following equation:
M 1 (t)＝S(t)*cos(2πft+φ 0 ) (formula 4)
Wherein S (t) is the received leaky wave receiving signal, f is the frequency of the leaky wave receiving signal, phi 0 Is the initial phase angle.
Then in the second state the leaky wave receiving signal M 2 (t) is expressed by the following equation:
M 2 (t)＝S(t)*cos(2πft+φ 0 + Pi) (type 5)
The process of microwave photonic radar system 10 using active modulation RFID device 20 to detect a target object is described below in conjunction with fig. 2. First, the microwave photonic radar system 10 executes step S1 to transmit a leaky wave transmitting signal through the leaky wave transmitting antenna, where the transmitted leaky wave transmitting signal is an ultrahigh frequency wireless signal. Then, the active-phase-modulation RFID device 20 performs step S2 to determine whether a leaky-wave transmission signal is received, and if a leaky-wave transmission signal is received, performs step S3 to output a low-frequency sine wave signal from the low-frequency signal source 25 and output a low-frequency pulse signal from the schmitt trigger 26.
If the leaky wave transmitting signal is not received, step S7 is performed, and the low frequency signal source 25 does not output the low frequency sine wave signal. For example, a circuit for detecting the current of the antenna 21 is arranged in the active phase modulation RFID device 20, if the current is formed on the antenna 21, it indicates that a leakage wave emission signal is received, and thus the low-frequency signal source 25 is controlled to start working; when the antenna 21 has no current, it indicates that no leakage wave transmitting signal is received, and accordingly the low frequency signal source 25 is controlled to stop working, so as to avoid that the diode D1 is in a switch state for a long time. And then, returning to the step S2 and continuously judging whether the leaky wave transmitting signal is received.
After the low-frequency signal generating circuit outputs a low-frequency signal, step S4 is performed to drive the on-off state of the diode D1 as a switching device to change, when the on-off state of the diode D1 changes, the reflection coefficient of the active phase modulation RFID device 20 changes between 1 and-1, and the antenna 21 reflects the received signal out, but the phase difference is 180 °. The signal reflected by the antenna 21 forms a leaky wave receiving signal, and the leaky wave receiving antenna 12 receives the leaky wave receiving signal, that is, step S5 is performed. Finally, the microwave photonic radar system 10 performs step S6 to calculate parameters such as the position of the target object by using the received microwave receiving signal.
Referring to fig. 3, when the microwave photonic radar system 10 calculates parameters such as the position of the target object, step S11 is first executed to record the transmission time t1 and the transmission frequency f1 of the leaky-wave transmission signal. Then, step S12 is executed to record the receiving time t2 and the transmitting frequency f2 of the leaky-wave receiving signal when the leaky-wave receiving signal is received. Then, step S13 is executed, a time difference between the emission time t1 of the leaky wave emission signal and the reception time t2 of the leaky wave reception signal is calculated, and the distance between the target object and the microwave photonic radar system is calculated by using the time difference and the wavelength of the leaky wave emission signal, that is, step S14 is executed.
Then, step S15 is executed to calculate the frequency difference between the transmitting frequency f1 of the leaky wave transmitting signal and the receiving frequency f2 of the leaky wave receiving signal, and step S16 is executed to calculate the moving direction of the target object by applying the doppler principle according to the frequency difference, wherein if the transmitting frequency f1 of the leaky wave transmitting signal is greater than the receiving frequency f2 of the leaky wave receiving signal, it indicates that the target object moves away from the microwave photon radar system, and if the transmitting frequency f1 of the leaky wave transmitting signal is less than the receiving frequency f2 of the leaky wave receiving signal, it indicates that the target object moves towards the microwave photon radar system. In addition, the radial moving speed of the target object can be calculated according to the frequency difference, and further the linear speed of the target object can be calculated.
According to the invention, the active phase modulation RFID device 20 is improved, so that the reflection coefficient of the active phase modulation RFID device 20 is changed between 1 and-1, the modulation coefficient M is increased, the power of a leaky wave receiving signal is increased, and the microwave photon radar system can calculate parameters such as the position, the moving direction and the moving speed of a target object more accurately.
Finally, it should be emphasized that the above-described preferred embodiments of the present invention are merely examples of implementations, not limitations, and various changes and modifications may be made by those skilled in the art, without departing from the spirit and scope of the invention, and any changes, equivalents, improvements, etc. made within the spirit and scope of the present invention are intended to be embraced therein.

Claims (10)

1. A target object detection method based on a microwave photon radar and an active phase modulation RFID device is characterized by comprising the following steps:
a microwave photon radar system transmits a leaky wave transmitting signal;
after an antenna of an active phase modulation RFID device arranged on a target object receives the leakage wave transmitting signal, the active phase modulation RFID device controls the change of the on-off state of a switch device, the reflection coefficient of the active phase modulation RFID device is enabled to be 1 when the switch device is switched on, the reflection coefficient of the active phase modulation RFID device is enabled to be-1 when the switch device is switched off, and the active phase modulation RFID device reflects the leakage wave transmitting signal to form a leakage wave receiving signal;
and the microwave photon radar system receives the leakage wave receiving signal reflected by the active phase modulation RFID device and calculates the position of the target object by applying the receiving leakage wave signal.
2. The method of claim 1, wherein the method comprises:
when the active phase modulation RFID device receives the leakage wave emission signal, the change of the conduction state of the switching device is controlled;
and when the active phase modulation RFID device does not receive the leakage wave emission signal, stopping controlling the change of the conduction state of the switching device.
3. The method of claim 2, wherein the method comprises:
the active phase modulation RFID device is provided with a low-frequency signal generating circuit, and the low-frequency signal generating circuit is used for outputting a low-frequency signal to the switching device so as to control the change of the on-off state of the switching device.
4. The method of claim 3, wherein the method comprises:
when the active phase modulation RFID device receives the leakage wave emission signal, the low-frequency signal generating circuit outputs the low-frequency signal to the switching device;
and when the active phase modulation RFID device does not receive the leakage wave emission signal, the low-frequency signal generating circuit stops outputting the low-frequency signal to the switching device.
5. The method for detecting target objects based on microwave photonic radar and active phase modulation RFID devices according to claim 3 or 4, wherein:
the switch device is a diode, an anode end of the diode receives the low-frequency signal, the low-frequency signal is a low-frequency pulse signal, the diode is switched on when the low-frequency pulse signal is at a high level, and the diode is switched off when the low-frequency pulse signal is at a low level.
6. The method of claim 3 or 4, wherein the method comprises:
the active phase-modulated RFID device includes an inductor connected between the low-frequency signal generation circuit and the switching device, and the low-frequency signal is output to the switching device through the inductor.
7. The method for detecting a target object based on a microwave photonic radar and an active phase modulation RFID device according to any one of claims 1 to 4, wherein:
the active phase modulation RFID device comprises an antenna and a load resistor, wherein the antenna, the load resistor and the switch device are sequentially connected, one end of the switch device is connected to the load resistor, and the second end of the switch device is grounded.
8. The method of claim 7, wherein the method comprises:
when the switching device is conducted, the antenna is short-circuited to the ground, so that the reflection coefficient of the active phase modulation RFID device is 1;
when the switching device is turned off, the antenna is opened, so that the reflection coefficient of the active phase modulation RFID device is-1.
9. The method for detecting a target object based on a microwave photonic radar and an active phase modulation RFID device according to any one of claims 1 to 4, wherein:
and after the microwave photon radar system receives the leaky wave receiving signal, calculating the position of the target object according to the time difference between the emission time of the leaky wave emission signal and the receiving time of the leaky wave receiving signal.
10. The method for detecting a target object based on a microwave photonic radar and an active phase modulation RFID device according to any one of claims 1 to 4, wherein:
and after receiving the leaky wave receiving signal, the microwave photon radar system calculates the moving direction of the target object according to the frequency difference between the leaky wave transmitting signal and the leaky wave receiving signal.
CN202211228425.9A 2022-10-09 2022-10-09 Target object detection method based on microwave photon radar and active phase modulation RFID device Pending CN115508856A (en)

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