Frequency Modulated Continuous Wave Radar System and Identity and Information Detection Method Thereof

Abstract

A frequency modulated continuous wave radar system and its identity and information detection method. The frequency modulated continuous wave radar system includes at least one identity tag, each of which is disposed adjacent to at least one person to be measured; and a frequency modulated continuous wave radar identity recognition device, including an identity recognition control module, which is used to control the identity tag to be measured in at least one identity tag to be activated so as to generate a specific tag reflection signal corresponding to the identity frequency in response to a linear frequency modulation signal; and a frequency modulated continuous wave radar, which is used to transmit a linear frequency modulation signal and receive at least one reflection signal of at least one person to be measured and a specific tag reflection signal in response to the linear frequency modulation signal, so as to calculate and determine whether the specific tag reflection signal and the specific reflection signal in the at least one reflection signal correspond to nearby position information. The frequency modulated continuous wave radar system and its identity and information detection method provided by the present invention can activate the tag reflector of a specific identity tag to have an identity frequency, so as to obtain the information of the person to be measured adjacent to the specific identity tag to be measured.

Description

Technical Field

[0001] The present invention relates to a frequency modulated continuous wave radar system and an identity and information detection method thereof, and in particular to a frequency modulated continuous wave radar system and an identity and information detection method thereof, wherein a tag reflector of a specific identity tag can be activated to have an identity frequency so as to obtain information of a person to be measured adjacent to the specific identity tag. Background Art

[0002] In recent years, vital sign detection technology has flourished (such as infrared body temperature measurement, blood sugar concentration detection, and blood oxygen concentration detection), which also includes non-personal physiological information detection. For example, non-contact heartbeat and respiratory rate detection devices can use radio frequency (RF) signals to the subject and receive corresponding reflected signals. This reflected signal will be modulated due to the subject's body movement (body displacement caused by heartbeat and breathing). After receiving, demodulating, filtering and amplifying the reflected signal, the algorithm inside the processor can calculate the subject's heartbeat and respiratory rate.

[0003] However, although conventional continuous wave (CW) radar technology can remotely measure physiological information such as breathing and heartbeat of a subject, it is difficult to accurately detect the breathing, heartbeat and other physiological information of a specific subject in a group of people. In addition, reflected signals caused by adjacent people or objects cause serious interference, which increases the difficulty of measurement.

[0004] In view of this, there is a need to improve the prior art. Therefore, it is necessary to provide a frequency modulated continuous wave radar system and its identity and information detection method to solve the above problems. Summary of the Invention

[0005] Therefore, the main object of the present invention is to provide a frequency modulated continuous wave radar system and its identity and information detection method that can activate the tag reflector of a specific identity tag with an identity frequency to obtain the desired information of a person to be measured near the specific identity tag.

[0006] The present invention discloses a frequency modulated continuous wave radar system, which includes at least one identity tag and a frequency modulated continuous wave radar identity recognition device. The at least one identity tag is respectively set next to at least one person to be tested. The frequency modulated continuous wave radar identity recognition device includes an identity recognition control module and a frequency modulated continuous wave radar. The identity recognition control module is used to send a control signal to control the activation of an identity tag to be tested among the at least one identity tag, so that a specific identity tag generates a specific tag reflection signal corresponding to an identity frequency in response to a linear frequency modulation signal. The frequency modulated continuous wave radar is used to transmit the linear frequency modulation signal and receive at least one reflection signal of the at least one person to be tested and the specific tag reflection signal in response to the linear frequency modulation signal, so as to calculate and determine whether the specific tag reflection signal and a specific reflection signal among the at least one reflection signal correspond to a similar position information. The specific reflection signal corresponds to the information of the person to be tested.

[0007] The present invention further discloses an identity and information detection method for a frequency modulated continuous wave radar system, and includes respectively setting at least one identity tag next to at least one person to be measured; sending a control signal to control the activation of one of the at least one identity tags to be measured; a frequency modulated continuous wave radar emitting a linear frequency modulation signal; a specific identity tag generating a specific tag reflection signal corresponding to an identity frequency in response to the linear frequency modulation signal; and the frequency modulated continuous wave radar receiving at least one reflection signal of the at least one person to be measured and the specific tag reflection signal in response to the linear frequency modulation signal, to calculate and determine whether the specific tag reflection signal and a specific reflection signal of the at least one reflection signal correspond to a similar position information; wherein the specific reflection signal corresponds to information of the person to be measured.

[0008] The frequency modulated continuous wave radar system and identity and information detection method provided by the present invention can activate the tag reflector of a specific identity tag with an identity frequency to obtain the information of a person to be measured adjacent to the specific identity tag. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 Schematic diagram of a frequency modulated continuous wave radar.

[0010] Figure 2A Schematic diagram of the time variation of the linear frequency modulation signal.

[0011] Figure 2B Schematic diagram of linear frequency modulation signal, reflected signal and intermediate frequency signal.

[0012] Figure 3 FIG. 1 is a schematic diagram of a frequency modulated continuous wave radar system according to an embodiment of the present invention.

[0013] Figure 4FIG2 is a schematic diagram of the operation of another FMCW radar system according to an embodiment of the present invention.

[0014] Figure 5 Schematic diagram of the identity and information detection process according to the first embodiment of the present invention.

[0015] Figure 6 FIG. 1 is a schematic diagram of the operation of a processing unit according to an embodiment of the present invention.

[0016] Figure 7 Schematic diagram of determining the arrival angle of a reflected signal of a linear frequency modulation signal according to an embodiment of the present invention.

[0017] Description of main component symbols:

[0018] 10 Frequency Modulated Continuous Wave Radar

[0019] 100 Linear FM Synthesizer

[0020] 102 Transmitting Antenna

[0021] 104 Receiving Antenna

[0022] 106 Low-pass filter (or band-pass filter)

[0023] 108 Analog-to-digital converter

[0024] 110 processors

[0025] 112 Mixer

[0026] 30, 40 FMCW radar systems

[0027] 32 FMCW radar identification device

[0028] 300 Identity Recognition Control Module

[0029] 302 FMCW radar

[0030] 304 Tag Antenna

[0031] 306 Tag wireless communication unit

[0032] 308 Tag Controller

[0033] 310 Label Reflector

[0034] 312 control unit

[0035] 314 Wireless Communication Unit

[0036] 316 Control Antenna

[0037] 318 Linear Frequency Modulation Synthesizer

[0038] 320 Transmitter Circuit

[0039] 322 Transmitting Antenna

[0040] 324 Receiving Antenna

[0041] 326 Receiving Circuit

[0042] 328 demodulation unit

[0043] 330 Analog-to-Digital Converter

[0044] 332 processing unit

[0045] 50 Process

[0046] Steps 500-524

[0047] 700, 702 sub-receiving antennas

[0048] TX, TX' linear frequency modulation signal

[0049] RX reflected signal

[0050] IF, IF' intermediate frequency signal

[0051] IDT, IDT1~IDTn identity tags

[0052] RXH, RXH1~RXHn reflected signal

[0053] RXT, RXT1~RXTn tag reflection signal

[0054] CON control signal

[0055] M1-M3 matrix

[0056] Tc period

[0057] S modulation slope

[0058] d, d' distance

[0059] τ time

[0060] Sτ, f frequency

[0061] θ Angle of arrival DETAILED DESCRIPTION

[0062] Please refer to Figure 1 , Figure 1Figure 1 is a schematic diagram of a frequency modulated continuous wave (FMCW) radar 10. The difference between FMCW radar 10 and CW radar is that CW radar transmits a continuous signal of the same frequency, while FMCW radar 10 transmits a modulated frequency signal. In simple terms, FMCW radar 10 includes a chirp synthesizer 100 that generates a chirp signal TX, which is then transmitted through a transmit antenna 102 via a transmit circuit. When the linear frequency modulation signal TX strikes an object (such as a person under test), a reflected signal RX is generated. The reflected signal RX is received by a receiving antenna 104 and then coupled by a mixer 112. The coupled output signal is filtered out by a low-pass filter or a band-pass filter 106 to remove high-frequency signals (such as the linear frequency modulation signal TX and the reflected signal RX) to generate an intermediate frequency signal IF. This signal is then converted into a digital signal by an analog-to-digital converter (ADC) 108 and processed by a processor 110 to obtain distance, direction, and vital signs.

[0063] Please refer to Figure 2A and Figure 2B , Figure 2A It is a schematic diagram of the time variation of the linear frequency modulation signal TX. Figure 2B Schematic diagram of linear frequency modulation signal TX, reflected signal RX, and intermediate frequency signal IF. Figure 2A As shown in the lower part, the frequency of the linear frequency modulation signal TX increases linearly with a modulation slope S over time, so Figure 2A As shown in the upper part, the period of the linear frequency modulation signal TX gradually becomes narrower in the time domain; Figure 2B As shown in the upper part, the reflected signal RX is received after a time τ after the linear frequency modulation signal TX is transmitted, so Figure 2B As shown in the lower part, an intermediate frequency signal IF with a frequency Sτ can be obtained, and the relationship can be expressed as follows:

[0064] TX==A T sin(w1t+Φ1)

[0065] RX=A R sin(w2t+Φ2)

[0066] IF=A B sin((w1-w2)t+(Φ1-Φ2))

[0067] =A B sin(2πf0)t+Φ0)

[0068] f0=f1-f2=Sτ=2Sd / C

[0069] Φ0=(2π*2d) / λ=4πd / λ

[0070] τ=2d / C

[0071] Where d is the distance between the subject and the FMCW radar 10, C is the signal propagation speed (the speed of light), and the remaining representations of amplitude, angular velocity, phase, frequency, and wavelength are well known in the art and are not further described here. As can be seen from the above equations, the frequency f0 of the intermediate frequency signal IF implicitly contains information about the subject's distance d, and the phase Φ0 of the intermediate frequency signal IF implicitly contains physiological information such as the subject's breathing and heartbeat (body displacement caused by breathing and heartbeat is approximately 1-2 mm and does not affect the frequency within a single millimeter wave wavelength of 12.5 mm). Therefore, the processor 110 can calculate the subject's distance, direction, breathing, and heartbeat through calculation.

[0072] On the other hand, please refer to Figure 3 , Figure 3 Figure 3 is a schematic diagram of an FMCW radar system 30 according to an embodiment of the present invention. The FMCW radar system 30 includes an identity tag (IDT) and an FMCW radar identification device 32. The FMCW radar identification device 32 includes an identification control module 300 and an FMCW radar 302. The IDT includes a tag antenna 304, a tag wireless communication unit 306, a tag controller 308, and a tag reflector 310. The identification control module 300 includes a control unit 312, a wireless communication unit 314, and a control antenna 316. The FMCW radar 302 includes a chirp synthesizer 318, a transmitting circuit 320, a transmitting antenna 322, a receiving antenna 324, a receiving circuit 326, a demodulation unit 328, an analog-to-digital converter 330, and a processing unit 332.

[0073] In short, the operation of the FMCW radar 302 is similar to that of the FMCW radar 10, which determines the distance, direction, respiration, and heart rate of a subject. The main difference between the FMCW radar system 30 and the FMCW radar 10 is that the FMCW radar system 30 places a switchable ID tag IDT (when switched on, the tag reflector 310 can vibrate in a specific manner, for example, to cause a tag reflection signal RXT to have a phase change corresponding to an identity frequency) near the subject. The identity recognition control module 300 then transmits a control signal CON via wireless communication to switch the ID tag IDT on. After transmitting a chirp signal TX', the FMCW radar 302 receives a reflection signal RXH from the subject and a tag reflection signal RXT from the ID tag IDT, which are then processed to determine the subject's distance, direction, and physiological information (respiration and heart rate), as well as the distance, direction, and identity frequency of the ID tag IDT. In this case, since unactivated ID tags do not reflect the tag reflection signal containing identification information (e.g., identification frequency), FMCW radar 302 can calculate the physiological information of the subject at the same distance and direction and combine it with the ID tag IDT to determine the individual's physiological information for the respiratory and heartbeat data being measured. In this way, the present invention can activate the tag reflector of a specific ID tag with the identification frequency to obtain the physiological information of the subject being measured, who is adjacent to the specific ID tag.

[0074] For example, see Figure 4 , Figure 4 FIG2 is an operational diagram of an FMCW radar system 40 according to an embodiment of the present invention. The FMCW radar system 40 is substantially identical to the FMCW radar system 30, and therefore, components and signals having similar functions are represented by the same symbols for simplicity. The main difference between the FMCW radar system 40 and the FMCW radar system 30 is that the FMCW radar system 40 includes different identity tags IDT1 to IDTn (having the same structure as the identity tag IDT) that are respectively arranged next to different persons to be tested (e.g., on their hands). Therefore, when the identity recognition control module 300 sends a control signal CON via wireless communication to control an identity tag IDT2 to be tested to be turned on (corresponding to the identity frequency) while other identity tags are turned off, the FMCW radar system 40 is not affected by the FMCW radar system 30. After transmitting the linear frequency modulation signal TX', the CW radar 302 receives and processes reflection signals RXH1-RXHn from the subject in response to the linear frequency modulation signal TX', as well as a tag reflection signal RXT2 corresponding to the identification frequency of the ID tag IDT2 (the tag reflection signals of other ID tags represented by dashed lines do not correspond to the identification frequency and cannot be detected). Therefore, the CW radar 302 calculates and determines whether the reflection signal RXH2 and the tag reflection signal RXT2 correspond to similar position information (distance, direction), and can obtain the desired physiological information of the subject, such as respiration and heartbeat, from the reflection signal RXH2.

[0075] Please continue to refer to Figure 3 Specifically, the control unit 312 is the control center of the FMCW radar identification device 32 . It can wirelessly communicate with the tag antenna 304 and the tag wireless communication unit 306 of the ID tag IDT via the wireless communication unit 314 and the control antenna 316 , and instruct the tag controller 308 of the ID tag IDT to activate or deactivate the tag reflector 310 . The wireless communication can utilize radio frequency identification (RFID), Wi-Fi, Bluetooth, ZigBee, or other wireless communication technologies.

[0076] Then, the control unit 312 can control the FMCW radar 302 to perform FMCW detection. The FMCW radar 302 operates similarly to the FMCW radar 10. The linear frequency modulation synthesizer 318 can generate a linear frequency modulation signal TX'. Each linear frequency modulation sub-signal in the linear frequency modulation signal TX' can be as follows: Figure 2A The RF oscillation signal shown has a starting frequency of 77 GHz and an ending frequency of 81 GHz, a time period of 40 μs, and a modulation slope S of 100 MHz / μs. However, other signal specifications (such as a starting frequency of 24 GHz) are also possible. The transmitting circuit 320 includes a power amplifier (PA) that amplifies the chirp signal TX' and transmits it via the transmitting antenna 322. The design of the transmitting antenna 322 is dependent on the selected RF frequency and the effective transmission angle (FOV).

[0077] When the tag reflector 310 is activated, the identity tag IDT receives the linear frequency modulation signal TX' and can generate a tag reflection signal RXT corresponding to the identity frequency in response to the linear frequency modulation signal TX'. Therefore, the receiving antenna 324 can receive the reflected signal of the linear frequency modulation signal TX' transmitted by the transmitting antenna 322 (including the reflected signal caused by the human body, the identity tag IDT, and stationary or moving objects in the environment). The receiving circuit 326 can then perform front-end signal amplification and front-end filtering on the reflected signal. It should be noted that the design of the receiving antenna 324 needs to consider the frequency range of the received RF signal and whether it is necessary to identify the direction of the object to be detected. If direction identification is required, the design of multiple transmitting or receiving antennas must be considered.

[0078] In this case, although the primary frequencies of the different reflected signals are the same as the chirp signal TX', the different reflected signals exhibit different characteristics. For example, the reflection intensities of different objects vary (the human body or metal has a stronger reflection intensity). Furthermore, the phase variation of the reflected signal RXH, generated by chest displacement due to breathing and heartbeat, corresponds to a specific physiological frequency, while the tag reflected signal RXT corresponds to a specific identity frequency (e.g., the vibration frequency of the vibrator in the tag reflector 310, the rotational frequency of a motor, or the modulation frequency of the radar cross-section (RCS)). Furthermore, reflected signals at different distances exhibit different modulation frequency differences.

[0079] In addition, the demodulation unit 328 can demodulate (e.g., couple) the current linear frequency modulation signal TX' generated by the linear frequency modulation synthesizer 318 and the reflected signal (including the reflected signal RXH and the tag reflected signal RXT) received by the receiving circuit 326, and remove the radio frequency signal (e.g., the linear frequency modulation signal TX', the reflected signal RXH, and the tag reflected signal RXT) from the demodulated signal through a low-pass filter to obtain an intermediate frequency signal IF'. Next, the analog-to-digital converter 330 converts the analog intermediate frequency signal IF' into a digital form to facilitate processing by the processing unit 332. The processing unit 332 then uses various digital processing algorithms to remove noise, high-frequency signals, and inappropriate respiratory harmonics to calculate the distance, direction, identity information of the identity tag IDT (e.g., identity frequency), human body distance and breathing, heartbeat, and other physiological information of the subject to be detected. Finally, the control unit 312 compares the distance and direction to find the identity information of the identity tag IDT at the same (close) distance (and / or direction) and the physiological information of the person being tested, such as human breathing and heartbeat, and thereby determines that the physiological information (breathing, heartbeat) belongs to the person being tested corresponding to the identity tag IDT (or the comparison is performed by the processing unit 332, and the two can also be integrated into a single processor).

[0080] The operation of the FMCW radar systems 30 and 40 can be summarized as the identity and information detection process 50. Figure 5 , Figure 5 FIG. 5 is a schematic diagram of an identity and information detection process 50 according to an embodiment of the present invention. Figure 5As shown, the FMCW radar identification device 32 can search for the identity tags IDT1-IDTn through the wireless communication unit 314 and control the identity tag IDT2 to be detected to turn on (step 502), so that the identity tag IDT2 to be detected turns on to activate a corresponding tag reflector with an identity frequency (step 504), wherein the identity frequency is a vibration frequency of a vibrator in the corresponding tag reflector, a rotation frequency of a motor, or a modulation frequency of a radar cross-section (RCS). Next, the FMCW radar identification device 32 activates the FMCW radar 302 (step 506), and the transmitting circuit 320 amplifies the linear frequency modulation signal TX' generated by the linear frequency modulation synthesizer 318 and transmits it through the transmitting antenna 322 (step 508), wherein the linear frequency modulation signal TX' includes N linear frequency modulation sub-signals (which can be as shown in FIG. Figure 2A As shown, the frequency increases linearly from a starting frequency of 77 GHz to an ending frequency of 81 GHz in each cycle).

[0081] Next, the receiving antenna 324 receives the reflected signal of the chirp signal TX' (step 510). The receiving circuit 326 performs front-end signal amplification and filtering on the reflected signal (step 512). The demodulation unit 328 then couples the current chirp signal TX' with the reflected signal and passes the demodulated signal through a low-pass filter to remove the RF signal to obtain an intermediate frequency (IF) signal IF' (step 514). The analog-to-digital converter 330 converts the analog intermediate frequency (IF) signal IF' into a digital form (step 516).

[0082] Please refer to Figure 6 , Figure 6 FIG. 3 is a schematic diagram of the operation of the processing unit 332 according to an embodiment of the present invention. Figure 6 As shown, the processing unit 332 first forms a matrix M1 by combining the parts of the N linear frequency modulation sub-signals corresponding to the linear frequency modulation signal TX' in the digital intermediate frequency signal IF'. The horizontal part of the matrix M1 is the sampling points within one period Tc of the linear frequency modulation sub-signal, and the vertical part is the different linear frequency modulation sub-signals numbered 1 to N (different from Figure 2A As shown, the final intensity of each linear frequency modulation sub-signal in each period Tc may be zero to prevent the reflected signal of the previous linear frequency modulation sub-signal from affecting the demodulation of the next linear frequency modulation sub-signal).

[0083] Next, the processing unit 332 performs a range fast Fourier transform (Range FFT) on each column (horizontal data) of the digital intermediate frequency signal IF' to obtain a matrix M2 (step 518). The horizontal portion is the range frequency of each linear frequency modulation sub-signal (which can be calculated based on the frequency of the linear frequency modulation sub-signal). Figure 2B and related formulas to calculate the corresponding distance). The vertical portion is composed of different linear frequency modulation sub-signals numbered 1 to N. In the analyzed distance frequency distribution diagram, if there is a distance frequency exceeding a preset intensity, it indicates that an object is present at the distance corresponding to that distance frequency (for example, the reflected signal from a human body designed with a strong reflective intensity or an activated reflector may exceed the preset intensity). The intensity of these distance frequencies represents the intensity of the reflected signal from the object at the corresponding distance. The distance frequency can be converted into a corresponding distance based on the slope of the N linear frequency modulation sub-signals of the linear frequency modulation signal TX'. Each frequency peak represents the distance at which the object is present, i.e., the shaded array in the matrix M2. In other words, the processing unit 332 can perform a range fast Fourier transform on the intermediate frequency signal IF' to determine whether at least one signal strength of at least one distance frequency in the intermediate frequency signal IF' is greater than a preset intensity and whether at least one person under test and the identity tag under test IDT2 are located at at least one distance corresponding to the at least one distance frequency (step 520).

[0084] The processing unit 332 then performs a longitudinal Doppler Fast Fourier Transform (Doppler-FFT) on the data at the frequency peaks (i.e., the shaded areas) in the matrix M2 generated by the range fast Fourier transform. This results in a matrix M3 containing phase change information of the intermediate frequency signal IF'. The phase change information represents phase frequency information of an object at a relative distance (e.g., physiological frequency information of breathing or heartbeat, the vibration frequency of a reflector's vibrator, the rotational frequency of a motor, or the modulation frequency of a radar cross-section, or information on the object's motion. Such small displacements cannot be detected in the frequency domain of the intermediate frequency signal IF', but cause intensity changes in different linear frequency modulation sub-signals, which can be obtained by the Doppler Fast Fourier Transform). The horizontal portion of the matrix M3 represents the range frequency (representing the distance) of each linear frequency modulation sub-signal, while the vertical portion represents the phase frequency distribution of the phase change (i.e., the magnitude of the phase frequency of the phase change at a certain distance).

[0085] In this case, the control unit 312 can determine whether each phase frequency peak value of the vertical axis of the matrix M3 after the Doppler fast Fourier transform is the identity frequency of the identity tag IDT2 to be measured. If it is the identity frequency of the identity tag IDT2 to be measured, it means that the corresponding distance is the distance position where the identity tag IDT2 to be measured is located. After finding the distance position where the identity tag IDT2 to be measured is located, the control unit 312 then determines whether there are other phase frequency peak values at the adjacent distance (vertical axis). If there are other phase frequency peak values, the control unit 312 analyzes whether they contain physiological information (such as the frequency of breathing or heartbeat). If there is physiological information (such as the frequency of breathing or heartbeat), it means that the physiological information of breathing or heartbeat is information possessed by the person to be measured of this identity tag IDT2 to be measured. In this way, the control unit 312 can identify an object (i.e., the identity tag IDT2 to be tested) with a specific phase frequency (such as vibration frequency, motor rotation frequency, or radar cross-section modulation frequency) based on the information processed by the FMCW radar 302, and use the physiological information (respiration, heartbeat) of the adjacent object as the physiological information of the person to be tested of the identity tag IDT2 to be tested, and use the distance position as the distance position of the person to be tested.

[0086] For example, the identity frequency of the ID tag under test (IDT2) is typically set higher than physiological frequencies such as breathing and heartbeat (e.g., a vibration frequency set to 1 kHz, or a radar cross-section modulation frequency set to 5 kHz) to reduce misjudgments during processing. The control unit 312 may first determine that the identity frequency of the ID tag under test (IDT2) is at a specific frequency (distance) to the right of the matrix M3 (e.g., the shaded area in the upper right corner), and then determine that the phase frequency peak at a similar location below is the subject's physiological frequency, such as breathing or heartbeat. In other words, the processing unit 332 performs a Doppler Fast Fourier Transform on at least one component of the intermediate frequency signal IF' that has undergone a range Fast Fourier Transform (FFT) and corresponds to at least one range frequency greater than a predetermined intensity (i.e., the shaded area in the matrix M2) (step 522). This allows the control unit 312 to determine that the identity frequency is at the specific distance and that at least one phase frequency in the intermediate frequency signal IF' that is located at a similar distance and has similar position information corresponds to the subject's physiological information (step 524).

[0087] It is worth noting that the main feature of the above embodiment is that the tag reflector of the specific identity tag can be activated to have an identity frequency to obtain the physiological information of the person to be measured who is adjacent to the specific identity tag. Those skilled in the art can make modifications or changes accordingly, without being limited to this. For example, in the above embodiment, the current linear frequency modulation signal TX' is coupled with the reflected signal to obtain the intermediate frequency signal IF', and then the distance frequency in the intermediate frequency signal IF' with a signal strength greater than a preset strength is determined to be the distance of the human body or the activated reflector, and then at least one phase frequency with a close distance to the identity frequency is determined to have close position information and corresponds to the physiological information of the person to be measured. In other embodiments, in addition to having a close distance, it is also necessary to consider having a close direction in order to determine whether there is close position information.

[0088] Please refer to Figure 7 , Figure 7 FIG. 1 is a schematic diagram of determining the angle of arrival (AOA) of the reflected signal of the linear frequency modulation signal TX' according to an embodiment of the present invention. Figure 7 As shown, receiving antenna 324 may include receiving sub-antennas 700 and 702, separated by a distance d', for receiving reflected signals RXH1-RXHn and the tag reflected signal RXT to determine multiple corresponding arrival angles. Specifically, due to the different distances between the object to be detected and receiving sub-antennas 700 and 702, the reflected signal of the linear frequency modulation signal TX' transmitted by transmitting antenna 322 arrives at the receiving sub-antennas 700 and 702 at different times, resulting in a difference in the phase of the reflected signal. This phase difference can be expressed as follows:

[0089]

[0090] Here, θ represents the arrival angle of the reflected signal. Therefore, the direction of the object to be detected can be detected by the phase difference of the reflected signals received by the sub-receiving antennas 700 and 702, and the object is judged to have similar position information only when the distance and direction are close.

[0091] For example, if Figure 7 As shown below, the phase frequencies obtained after the range fast Fourier transform and the Doppler fast Fourier transform of the intermediate frequency signal IF' contain information about their respective angles of arrival. Therefore, after determining that at least one phase frequency and the identity frequency have a close distance, it is also necessary to determine that at least one phase frequency and the identity frequency have a close direction. Only then can it be determined that at least one phase frequency and the identity frequency have close position information and correspond to the physiological information of the subject (i.e., the close position information includes a close distance and a close direction). In addition, Figure 7In the illustrated embodiment, two sub-receiving antennas 700 and 702 are used to determine the direction of the object to be detected. However, in other embodiments, more sub-receiving antennas may be added to increase the resolution and accurately detect the directions of multiple objects.

[0092] In addition, in the above embodiment, the identification frequency is a vibration frequency of a vibrator, a rotational frequency of a motor, or a modulation frequency of a radar cross section in the activated tag reflector 310. However, the implementation of the tag reflector 310 is not limited to this, as long as the tag reflector 310, when activated, causes the reflected signal to have a phase change corresponding to the identification frequency. In short, the tag reflector 310 may include a vibrator that generates specific vibrations and reflects the chirp signal TX', or it may backscatter in response to and modulate the chirp signal TX' (e.g., by modulating the radar cross section).

[0093] In one embodiment of the tag reflector 310, to generate vibration, a speaker diaphragm can be used and provided with a specific vibration signal (e.g., a specific vibration frequency serving as an identification frequency), or a mobile phone vibrator can be used. Furthermore, to effectively increase the reflected signal strength of the modulated chirp signal TX', the speaker diaphragm can be coated with a metal film, or the speaker diaphragm structure can be designed to resemble a corner reflector (or a collection of miniature corner reflectors) to enhance the reflected signal strength of the modulated chirp signal TX'.

[0094] Specifically, the corner reflector can be a right-angled pyramid structure or a dihedral corner reflector. This geometric structure can reflect the incident signal back parallel to the incident signal, thereby achieving a better radar cross-section. Furthermore, if a speaker diaphragm is designed with only a single corner reflector, it will be too thick. Therefore, a collection of multiple miniaturized corner reflectors can be designed on the speaker diaphragm. By reducing the size, the overall structure can be made thinner while maintaining a similar radar cross-section. When a speaker diaphragm or mobile phone vibrator has a corner reflector or a collection of miniaturized corner reflectors, when a selected vibration frequency (i.e., an identity frequency) is applied to the speaker diaphragm or mobile phone vibrator, the reflected signal exhibits a significant change corresponding to the identity frequency, allowing distance and identity frequency to be analyzed. The above embodiments primarily utilize the fact that the speaker diaphragm or mobile phone vibrator can vibrate at the vibration frequency and has a corner reflector structure as a reflective surface. The remaining speaker features are well known to those skilled in the art and are not detailed here for the sake of brevity.

[0095] Furthermore, in another embodiment of the tag reflector 310, a motor can be used to control a metal reflector to rotate at a rotation frequency (ie, identity frequency), so that the reflection area (radar cross section) of the metal reflector relative to the modulated linear frequency modulation signal TX' changes according to the rotation frequency.

[0096] In another embodiment of the tag reflector 310, an actively controlled frequency selective surface (FSS) backscatter transponder can be used. The FSS consists of a dipole equipped with a switching PIN diode. The transponder controls the diode bias to modulate the FSS's radar cross section, thereby modulating the tag's backscatter response to the FMCW radar 302. Appropriate selection of the PIN diode and FSS resonator design can accommodate the sweep frequency of the chirp signal TX' used by the FMCW radar 302. For example, when the PIN diode is conducting, the FSS antenna length is longer. This antenna length can be appropriately designed to resonate with the chirp signal TX', resulting in a stronger reflected signal. Therefore, the diode bias can be controlled to modulate the FSS's radar cross section according to the modulation frequency, causing the reflected signal to vary in strength corresponding to the modulation frequency (identification frequency).

[0097] In another embodiment of the tag reflector 310, an actively controlled integrated circuit resonator can be used. After the integrated circuit receives the linear frequency modulation signal TX' via an antenna, a resonant signal is generated through a matching network and resonator. A control signal then determines whether to transmit the resonant signal as a reflected signal based on the modulation frequency. Specifically, the resonant signal generated by the resonator is modulated based on the modulation frequency, causing the reflected signal to vary in intensity according to the modulation frequency (identification frequency).

[0098] It is worth noting that in the above embodiment, after the tag reflector 310 is activated with the identity frequency, the tag reflected signal RXT may not only have a phase change corresponding to the identity frequency. Due to the coupling of the identity frequency with the frequency of the chirp signal TX', the tag reflected signal RXT may also have a frequency that is equal to the frequency of the corresponding chirp signal TX' plus or minus the identity frequency. This results in the distance frequency observed by the ID tag under test (IDT) being equal to the actual distance frequency plus or minus the identity frequency. In this case, after performing a distance fast Fourier transform, two distance frequencies corresponding to the identity frequency of the ID tag under test (IDT) can be found. The two distance frequencies are then added and averaged to obtain the actual distance frequency. The two distance frequencies are then subtracted and averaged to obtain the identity frequency.

[0099] In addition, in the above-mentioned embodiment, the identity tag is set next to the person to be tested to detect the physiological information of the person to be tested. However, in other embodiments, the person to be tested may also be a non-human object and other information of the person to be tested may be detected. For example, the present invention may also be applied to detecting the location of a specific object. Specifically, the frequency modulated continuous wave radar can detect the distance and speed of an object, but it does not know what the object is. After the identity tag is set on an object (such as a car), when the car moves (or is stationary), the frequency modulated continuous wave radar 302 can determine that the object is a car with an identity tag based on the fact that the distance and speed of the object detected are the same (or similar) as the distance and speed of the identity tag detected.

[0100] Furthermore, the tag controller 308, the control unit 312, and the processing unit 332 may be processors, such as a microprocessor or an application-specific integrated circuit (ASIC). The ID tag IDT and the FMCW radar identification device 32 may each include a storage unit. The storage unit may be any data storage device that stores a program code and reads and executes the program code via the processor to perform the aforementioned operations. The storage unit may be, but is not limited to, a subscriber identity module (SIM), a read-only memory (ROM), a random-access memory (RAM), a CD-ROM, magnetic tapes, floppy disks, optical data storage devices, and the like.

[0101] In summary, the present invention can activate the tag reflector of a specific identity tag with an identity frequency to obtain information of a person to be measured who is adjacent to the specific identity tag.

[0102] The above descriptions are merely preferred embodiments of the present invention. Any equivalent changes and modifications made within the scope of the claims of the present invention should fall within the scope of the present invention.

Claims

1. A frequency modulated continuous wave radar system, comprising: At least one identity tag, each of which is disposed next to at least one person to be tested; as well as A frequency modulated continuous wave radar identity recognition device, the frequency modulated continuous wave radar identity recognition device comprising: an identity recognition control module, the identity recognition control module being configured to send a control signal to control a to-be-tested identity tag among the at least one identity tag to be turned on, so that a specific identity tag generates a specific tag reflection signal corresponding to an identity frequency in response to a linear frequency modulation signal; and a frequency modulated continuous wave radar configured to transmit the linear frequency modulation signal and receive at least one reflected signal of the at least one object under test and the reflected signal of the specific tag in response to the linear frequency modulation signal, so as to calculate and determine whether the reflected signal of the specific tag and a specific reflected signal among the at least one reflected signal correspond to a similar position; The specific reflection signal corresponds to information of a person under test; The FMCW radar demodulates and low-pass filters the current linear frequency modulation signal, the at least one reflected signal, and the specific tag reflected signal to generate an intermediate frequency signal; The FMCW radar performs a Doppler fast Fourier transform on at least one component of the intermediate frequency signal that undergoes a range fast Fourier transform, corresponding to at least one range frequency greater than a predetermined intensity, to determine that the identity frequency is located at a close distance to the close position information and that at least one phase frequency in the intermediate frequency signal located at the close distance corresponds to the information of the person under test.

2. The FMCW radar system as claimed in claim 1 , wherein the ID tag to be detected is turned on to activate a corresponding reflector having the ID frequency, and the ID frequency is a vibration frequency of the corresponding reflector, a rotation frequency of a motor, or a modulation frequency.

3. The FMCW radar system as claimed in claim 1, wherein the linear frequency modulation signal comprises a plurality of linear frequency modulation sub-signals, each of the plurality of linear frequency modulation sub-signals linearly increasing from a starting frequency to an ending frequency in each cycle.

4. The FMCW radar system of claim 1 , wherein the FMCW radar performs the range fast Fourier transform on the intermediate frequency signal to determine whether at least one signal strength of the at least one range frequency in the intermediate frequency signal is greater than a predetermined strength and whether the at least one person to be detected and the identity tag to be detected are located at at least one distance corresponding to the at least one range frequency.

5. The FMCW radar system as claimed in claim 1 , wherein the FMCW radar comprises a plurality of sub-receiving antennas, the plurality of sub-receiving antennas being configured to receive the at least one reflected signal and the specific tag reflected signal to determine a plurality of corresponding arrival angles, and the close position information comprises a close distance and a close direction.

6. The FMCW radar system as claimed in claim 2 , wherein the corresponding reflector comprises a speaker diaphragm or a mobile phone vibrator that vibrates at the vibration frequency, and the speaker diaphragm or the mobile phone vibrator has a structure of a corner reflector or a miniaturized corner reflector assembly.

7. The FMCW radar system as claimed in claim 2, wherein the motor controls a metal reflector to rotate at the rotation frequency, so that a reflection area of the metal reflector relative to modulating the chirp signal changes according to the rotation frequency.

8. The FMCW radar system as claimed in claim 2, wherein a radar cross section of a frequency selective surface in the corresponding reflector is modulated according to the modulation frequency, or a resonance signal generated by a resonator in the corresponding reflector is modulated according to the modulation frequency.

9. A method for detecting an identity and information, the method being used in a frequency modulated continuous wave radar system, the method comprising: Setting at least one identity tag next to at least one person to be tested; Sending a control signal to control an identity tag to be tested among the at least one identity tag to be turned on; A frequency modulated continuous wave radar transmits a linear frequency modulated signal; A specific identity tag generates a specific tag reflection signal corresponding to an identity frequency in response to the linear frequency modulation signal; and The FMCW radar receives at least one reflected signal of the at least one object under test and the reflected signal of the specific tag in response to the linear frequency modulation signal, and calculates and determines whether the reflected signal of the specific tag and a specific reflected signal among the at least one reflected signal correspond to a close position information; The specific reflection signal corresponds to information of a person under test; The FMCW radar demodulates and low-pass filters the current linear frequency modulation signal, the at least one reflected signal, and the specific tag reflected signal to generate an intermediate frequency signal; The FMCW radar performs a Doppler fast Fourier transform on at least one component of the intermediate frequency signal that undergoes a range fast Fourier transform, corresponding to at least one range frequency greater than a predetermined intensity, to determine that the identity frequency is located at a close distance to the close position information and that at least one phase frequency in the intermediate frequency signal located at the close distance corresponds to the information of the person under test.

10. The identity and information detection method according to claim 9, further comprising: The ID tag to be tested is turned on to activate a corresponding reflector with the ID frequency. The ID frequency is a vibration frequency, a rotation frequency of a motor, or a modulation frequency in the corresponding reflector. 11 . The identity and information detection method as claimed in claim 9 , wherein the linear frequency modulation signal comprises a plurality of linear frequency modulation sub-signals, each of the plurality of linear frequency modulation sub-signals linearly increasing from a starting frequency to an ending frequency in each cycle.

12. The identity and information detection method of claim 9 , wherein the frequency modulated continuous wave radar performs the range fast Fourier transform on the intermediate frequency signal to determine that at least one signal strength of the at least one range frequency in the intermediate frequency signal is greater than the predetermined strength and that the at least one person to be detected and the identity tag to be detected are located at at least one distance corresponding to the at least one range frequency.

13. The identity and information detection method as claimed in claim 9, wherein the frequency modulated continuous wave radar includes a plurality of sub-receiving antennas, the plurality of sub-receiving antennas are used to receive the at least one reflected signal and the specific tag reflected signal to determine a plurality of corresponding arrival angles, and the close position information includes a close distance and a close direction.

14. The identity and information detection method as claimed in claim 10, wherein a speaker diaphragm or a mobile phone vibrator in the corresponding reflector vibrates at the vibration frequency, and the speaker diaphragm or the mobile phone vibrator has a structure of a corner reflector or a miniaturized corner reflector assembly. 15 . The identity and information detection method as claimed in claim 10 , wherein the motor controls a metal reflector to rotate at the rotation frequency, so that a reflection area of the metal reflector relative to the linear frequency modulation signal changes according to the rotation frequency. 16 . The identity and information detection method as claimed in claim 10 , wherein a radar cross section of a frequency selective surface in the corresponding reflector is modulated according to the modulation frequency, or a resonance signal generated by a resonator in the corresponding reflector is modulated according to the modulation frequency.

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