A radio frequency identification method and related device

Abstract

The present application provides a device related to a radio frequency identification method, which can be applied to the field of communications, especially the field of radio frequency identification, wherein a radio frequency identification method includes: receiving a first reflection signal; demodulating the first reflection signal to obtain the flipping moment of the first reflection signal; subjecting the single-tone signal to non-constant modulation to obtain a non-constant envelope signal, and transmitting the non-constant envelope signal to the passive tag after a target time period, wherein the trough of the non-constant envelope signal after transmission is aligned with the flipping moment of the first reflection signal; receiving a second reflection signal; demodulating the second reflection signal to obtain the tag information corresponding to the passive tag. Implementing the embodiments of the present application can reduce the problem of harmonic interference between multiple tags in passive tag radio frequency identification RFID during frequency division multiplexing.

Description

Technical Field

[0001] The present application relates to the field of radio frequency identification technology, and in particular to a radio frequency identification method and related devices. Background Art

[0002] In the current passive radio frequency identification technology (Passive Radio Frequency Identification, PassiveRFID) system, it often includes a reader, a passive tag (a chip with an antenna in the memory, which stores identifiable information), etc. Among them, unlike active tags with internal power supplies, passive tags have no internal power supplies and need to extract the energy required for their work from the excitation signal sent by the reader, so passive tags cannot form shaping filters independently, which leads to a large amount of harmonic interference in the reflected spectrum received by the reader when multiple passive tags reflect the excitation signal (the signal that provides energy for the passive tag) respectively. In order to reduce the occurrence of harmonic interference, time division multiplexing (i.e., identifying different passive tags at different times) can be used to identify multiple passive tags, but when multiple passive tags are identified by time division multiplexing, only one passive tag can be identified at the same time, and the identification efficiency is low. Therefore, in order to ensure the recognition efficiency of multiple passive tags, frequency division multiplexing (i.e., each passive tag has a different frequency) can be used for multiple passive tags for tag recognition, that is, multiple passive tags can be recognized at the same time to improve recognition efficiency. However, in the process of using the frequency division multiplexing method for tag recognition, multiple passive tags are reflected at the same time, and each passive tag is at a different frequency point, which will cause a large number of harmonic components in the reflected waveform, and due to the influence of the near-far effect, the harmonic components corresponding to the passive tags with larger reflection power among the multiple passive tags will interfere with the harmonic components corresponding to other passive tags with smaller reflection power, affecting the demodulation of other tags. Moreover, the harmonics of the passive tags may fall into the adjacent frequency band, affecting the demodulation of the passive tags at the adjacent frequency points, causing other passive tags to be unable to be read by the reader, reducing the overall reading rate of multiple passive tags.

[0003] Therefore, how to improve the reading rate of passive tags in frequency division multiplexing scenarios is a problem that needs to be solved. Summary of the invention

[0004] The embodiments of the present application provide a radio frequency identification method, system and related devices, which utilize carrier start and stop to reduce the problem of harmonic interference between multiple tags in passive tag radio frequency identification RFID during frequency division multiplexing identification.

[0005] In a first aspect, an embodiment of the present application provides a radio frequency identification method, which is applied to a receiver, and the method includes:

[0006] Receive a first reflected signal reflected by a passive tag based on a single-tone signal, wherein the passive tag is any one of a plurality of passive tags, and the single-tone signal is a signal with only one frequency; demodulate the first reflected signal to obtain a flipping moment of the first reflected signal; obtain a non-constant envelope signal by subjecting the single-tone signal to non-constant modulation, and transmit the non-constant envelope signal to the passive tag after a delay of a target time period, wherein a trough of the non-constant envelope signal after transmission is aligned with the flipping moment of the first reflected signal; receive a second reflected signal reflected by the passive tag based on the non-constant envelope signal; demodulate the second reflected signals corresponding to the plurality of passive tags respectively to obtain tag information corresponding to the plurality of passive tags respectively, wherein the tag information includes a tag identifier.

[0007] The cause of the harmonics reflected by the tag is that the excitation signal is a single-tone signal (i.e., a signal with only one frequency). When the tag performs OOK (On-off keying) modulation (switch modulation) reflection on it, a steep rising edge and falling edge will be generated, which contains rich harmonic components and will affect the demodulation of other tags. If the excitation signal is a non-constant envelope signal, at the moment of the passive tag OOK modulation reflection, the intensity of the excitation signal is weakened, so that the signal energy reflected by the tag is gradually weakened, and the steep edges are smoothed, so that the harmonics can be suppressed. Therefore, in order to achieve a better suppression effect on the harmonics reflected by the passive tag, the reflected signal based on the single-tone signal can be demodulated by implementing the embodiment of the present application to obtain the flipping moment of the passive tag. Then, a non-constant envelope waveform is emitted through non-constant modulation, so that the trough (the lowest energy point) of the waveform is aligned with the flipping moment of the passive tag Tag reflection signal, so that the waveform reflected by the passive tag is also a non-constant envelope signal, that is, the signal reflected by the passive tag is formed and filtered, and the purpose of suppressing harmonics is achieved.

[0008] In a possible implementation, the first reflected signal includes part or all of the tag information; the demodulating the first reflected signal to obtain the flipping moment of the first reflected signal includes: demodulating the first reflected signal reflected by the passive tag to obtain the initial reflection moment and period of the first reflected signal; according to the initial reflection moment and period of the first reflected signal, obtaining the flipping moment of the first reflected signal. In the implementation of the embodiment of the present application, if it is detected that the first reflected signal includes part or all of the tag information, it can be proved that the passive tag can normally reflect a single-tone signal or a non-constant envelope signal, and then the received reflected signal can be demodulated. If the tag does not start to reflect part or all of the tag information, it is necessary to wait in the current state to reduce the error rate of reading the passive tag. Among them, the tag information may include a 16-bit random number (Random number 16, Rn16) of a passive tag, an electronic product code (Electronic Product Code, Epc) or a tag identification of a passive tag, etc.

[0009] In a possible implementation, the non-constant modulation of the single-tone signal into a non-constant envelope signal, and the non-constant envelope signal is transmitted to the passive tag after a delay target time period, including: after the non-constant modulation of the single-tone signal into the non-constant envelope signal, the non-constant envelope signal is transmitted to the passive tag at t1+n*T-t2, wherein n is the smallest integer that makes n*T-t2>0, t1 is the initial reflection moment of the first reflection signal, t2 is the transmission time of transmitting the single-tone signal to the exciter, T is the period of the first reflection signal, and the exciter is an exciter that forwards the single-tone signal to the passive tag. Implementing the embodiment of the present application, for passive tags, the tag itself does not have an "active" shaping and filtering capability, that is, the tag cannot transmit a non-constant envelope waveform, and can only passively reflect the incident electromagnetic wave. If the incident electromagnetic wave is a waveform after shaping and filtering (non-constant envelope), the tag is also a waveform of a non-constant envelope after passive reflection, thereby achieving the effect of actively transmitting a non-constant envelope waveform.

[0010] In a possible implementation, the envelope of the non-constant modulation is in the form of: evp = abs(cos(2πf blf t)); or, evp = 1-abs(cos(2πf ｂlf t)), where f blf is the reflection link frequency of the first reflection signal. In the implementation of the present application, different forms of non-constant envelope waveform signals have different harmonic parts that are enhanced. When the envelope form of the non-constant modulation is evp=abs(cos(2πf blft)), the third harmonic can be greatly enhanced. When the envelope of the non-constant modulation is evp=1-abs(cos(2πf blf t)), the harmonics after the third are mainly enhanced. Therefore, different forms of envelope waveforms enhance different parts of harmonics, which can be flexibly selected according to actual needs to enhance the accuracy of reading passive tags.

[0011] In a possible implementation, the trough of the non-constant envelope signal after transmission is aligned with the flipping moment of the first reflected signal, including: the period of the non-constant envelope signal after transmission is within a preset period range, and the deviation between the trough of the non-constant envelope signal after transmission and the rising edge or falling edge of the first reflected signal does not exceed X*2÷f blf , the preset period range is: from (1-X)*2÷f blf to (1+X)*2÷f blf , where X is the preset error threshold, f blf is the reflection link frequency of the first reflection signal. In the implementation of the present application, as long as the transmitted carrier is in the form of a non-constant envelope, and the deviation between the rising edge or falling edge of the non-constant envelope signal and the passive tag reflection signal does not exceed the preset error threshold, it can be considered that the trough of the non-constant envelope signal is aligned with the tag reflection signal, and therefore the tag can be suppressed from generating a large number of harmonics, thereby suppressing harmonic interference.

[0012] In one possible implementation, the method further includes: transmitting the single-tone signal to an exciter, wherein the exciter is used to forward the single-tone signal to the passive tag, the passive tag is one of the N passive tags corresponding to the exciter, the N passive tags are N of the multiple passive tags, and N is a positive integer greater than 1. In the implementation of the embodiment of the present application, the transmitter and receiver in the original reader are separated through three-point passive radio frequency identification, and the single-tone signal is forwarded to multiple passive tags by frequency shifting through the exciter (equivalent to the transmitter), thereby realizing the physical separation and frequency separation of transmission and reception, making the transmission and reception different frequencies, thereby solving the problem of receiving saturation and increasing the distance for reading passive tags.

[0013] In a second aspect, an embodiment of the present application provides a radio frequency identification method, which is applied to an exciter, and the method includes:

[0014] Receive a single-tone signal sent by a receiver, wherein the single-tone signal is a signal with only one frequency; forward the single-tone signal to corresponding multiple passive tags, wherein the passive tag is one of N passive tags corresponding to the exciter, and the N passive tags are N of the multiple passive tags, where N is a positive integer greater than 1; receive a non-constant envelope signal sent by the receiver after a delay target time period, wherein the non-constant envelope signal is a signal obtained by non-constant modulation of the single-tone signal, and the trough of the non-constant envelope signal is aligned with the flipping moment of the first reflected signal; forward the non-constant envelope signal to the passive tag.

[0015] Implementing the embodiment of the present application, after the target time period is delayed, the non-constant envelope signal of the non-constant modulation of the receiver is sent to the passive tag, so that the trough (the lowest energy point) of the waveform is aligned with the flipping moment of the passive tag Tag reflection signal, wherein the non-constant envelope signal is obtained by non-constant modulation based on the single-tone signal, and the flipping moment is the moment when the rising edge and the falling edge of the reflection signal alternate. Since the excitation signal transmitted to the passive tag is a non-constant envelope signal, the waveform reflected by the passive tag is also a non-constant envelope signal, that is, the signal reflected by the passive tag is formed and filtered, and the purpose of suppressing harmonics is achieved, that is, the passive tag reflection harmonics have a good suppression effect.

[0016] In one possible implementation, the receiving of the non-constant envelope signal sent by the receiver after the target time period of delay includes: receiving the non-constant envelope signal sent by the receiver at time t1+n*T-t2, wherein n is the smallest integer that makes n*T-t2>0, t1 is the initial reflection time of the first reflection signal, t2 is the transmission time for the receiver to transmit the single-tone signal to the exciter, T is the period of the first reflection signal, the first reflection signal is the signal reflected by the passive tag based on the single-tone signal, the initial reflection time is the initial reflection time of the first reflection signal obtained after the receiver demodulates the first reflection signal, and the period is the period of the first reflection signal obtained after the receiver demodulates the first reflection signal. In implementing the embodiment of the present application, for passive tags, the tag itself does not have the "active" shaping and filtering capability, that is, the tag cannot transmit a non-constant envelope waveform and can only passively reflect the incident electromagnetic wave. Therefore, after delaying the target time period, a shaped and filtered (non-constant envelope) waveform is emitted to the passive tag, and the tag also emits a non-constant envelope waveform after passive reflection, thereby achieving the effect of actively emitting a non-constant envelope waveform. At the same time, the trough of the non-constant envelope signal is aligned with the flipping moment of the first reflected signal, which has a better suppression effect on the passive tag reflected harmonics.

[0017] In a third aspect, an embodiment of the present application provides a radio frequency identification device, applied to a receiver, the device comprising:

[0018] A first receiving unit is used to receive a first reflected signal reflected by a passive tag based on a single-tone signal, wherein the passive tag is any one of a plurality of passive tags, and the single-tone signal is a signal having only one frequency;

[0019] A first demodulation unit, used to demodulate the first reflected signal to obtain a flipping moment of the first reflected signal;

[0020] A modulation unit, used for obtaining a non-constant envelope signal by non-constant modulation of the single tone signal, and transmitting the non-constant envelope signal to the passive tag after a delay of a target time period, wherein a trough of the non-constant envelope signal after transmission is aligned with the flipping moment of the first reflected signal;

[0021] A second receiving unit, configured to receive a second reflected signal reflected by the passive tag based on the non-constant envelope signal;

[0022] The second demodulation unit is used to demodulate the second reflected signal to obtain tag information corresponding to the passive tag, where the tag information includes a tag identifier.

[0023] In one possible implementation, the first reflected signal includes part or all of the tag information; the first demodulation unit is specifically used to demodulate the first reflected signal reflected by the passive tag to obtain the initial reflection time and period of the first reflected signal; and obtain the flipping time of the first reflected signal according to the initial reflection time and period of the first reflected signal.

[0024] In one possible implementation, the modulation unit is specifically used to: after non-constantly modulating the single-tone signal into the non-constant envelope signal, start transmitting the non-constant envelope signal to the passive tag at time t1+n*T-t2, wherein n is the smallest integer that makes n*T-t2>0, t1 is the initial reflection time of the first reflected signal, t2 is the transmission time for transmitting the single-tone signal to the exciter, T is the period of the first reflected signal, and the exciter is an exciter that forwards the single-tone signal to the passive tag.

[0025] In a possible implementation, the envelope of the non-constant modulation is in the form of: evp = abs(cos(2πf blf t)); or, evp = 1-abs(cos(2πf blf t)), where f ｂlf is the reflection link frequency of the first reflected signal.

[0026] In a possible implementation, the modulation unit is specifically used to: the period of the non-constant envelope signal after transmission is within a preset period range, and the deviation between the trough of the non-constant envelope signal after transmission and the rising edge or falling edge of the first reflected signal does not exceed X*2÷f blf , the preset period range is: from (1-X)*2÷f blf to (1+X)*2÷f blf , where X is the preset error threshold, f blf is the reflection link frequency of the first reflected signal.

[0027] In one possible implementation, the device also includes: a transmitting unit, used to transmit the single-tone signal to an exciter, wherein the exciter is used to forward the single-tone signal to the passive tag, the passive tag is one of N passive tags corresponding to the exciter, the N passive tags are N of the multiple passive tags, and N is a positive integer greater than 1.

[0028] In a fourth aspect, an embodiment of the present application provides a radio frequency identification device, which is applied to an exciter, and the device includes:

[0029] A single tone unit, used to receive a single tone signal sent by a receiver, wherein the single tone signal is a signal having only one frequency;

[0030] A first forwarding unit, configured to forward the single tone signal to a corresponding plurality of passive tags, wherein the passive tag is one of N passive tags corresponding to the exciter, and the N passive tags are N of the plurality of passive tags, where N is a positive integer greater than 1;

[0031] A non-constant envelope unit, used for receiving a non-constant envelope signal sent by the receiver after a target delay period, wherein the non-constant envelope signal is a signal obtained by non-constant modulation of the single tone signal, and a trough of the non-constant envelope signal is aligned with a flipping moment of the first reflected signal;

[0032] The second forwarding unit is configured to forward the non-constant envelope signal to the passive tag.

[0033] In one possible implementation, the non-constant envelope unit is specifically used to: receive the non-constant envelope signal sent by the receiver at time t1+n*T-t2, wherein n is the smallest integer that makes n*T-t2>0, t1 is the initial reflection moment of the first reflection signal, t2 is the transmission time for the receiver to transmit the single-tone signal to the exciter, T is the period of the first reflection signal, the first reflection signal is the signal reflected by the passive tag based on the single-tone signal, the initial reflection moment is the initial reflection moment of the first reflection signal obtained after the receiver demodulates the first reflection signal, and the period is the period of the first reflection signal obtained after the receiver demodulates the first reflection signal.

[0034] In a fifth aspect, the present application provides a radio frequency identification system, which includes a receiver, one or more exciters, and multiple passive tags. The receiver is used to support the implementation of the functions involved in the method of the first aspect, for example, sending, receiving or demodulating the signals involved in the radio frequency identification method respectively; the one or more exciters are used to support the implementation of the functions involved in the method of the second aspect, for example, forwarding the signals involved in the radio frequency identification method to the multiple passive tags.

[0035] In a sixth aspect, an embodiment of the present application provides a computer storage medium for storing computer software instructions used for a radio frequency identification device provided in the third aspect above, which includes a program designed for executing the above aspect.

[0036] In a seventh aspect, an embodiment of the present application provides a computer storage medium for storing computer software instructions used for a radio frequency identification device provided in the fourth aspect above, which includes a program designed for executing the above aspect.

[0037] In an eighth aspect, an embodiment of the present application provides a computer program, which includes instructions. When the computer program is executed by a computer, the computer can execute the process executed by the radio frequency identification device in the third aspect above.

[0038] In a ninth aspect, an embodiment of the present application provides a computer program, which includes instructions. When the computer program is executed by a computer, the computer can execute the process executed by the radio frequency identification device in the fourth aspect above. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the background technology, the drawings required for use in the embodiments of the present application or the background technology will be described below.

[0040] Figure 1It is a spectrum diagram received by the receiver air interface when a group of 5 tags are frequency-division multiplexed and a corresponding demodulation bit error rate simulation schematic diagram provided in an embodiment of the present application.

[0041] Figure 2 It is a schematic diagram of the architecture of a radio frequency identification system provided in an embodiment of the present application.

[0042] Figure 3 It is the time domain and spectrum of a square wave signal provided in an embodiment of the present application.

[0043] Figure 4 This is a simulation schematic diagram of a passive tag reflection signal provided in an embodiment of the present application.

[0044] Figure 5 It is a flowchart of a radio frequency identification method provided in an embodiment of the present application.

[0045] Figure 6 This is a typical signaling flow chart of a 6C protocol transition inventory provided in an embodiment of the present application.

[0046] Figure 7 It is a schematic diagram of the timing relationship between a receiver, an exciter and a passive tag provided in an embodiment of the present application.

[0047] Figure 8 This application provides an application scenario of multi-tag identification in factory logistics.

[0048] Fig. 9 It is a flow chart of the radio frequency identification method in the multi-entry scenario of entering and exiting the warehouse provided by this application.

[0049] Fig.10 This is a set of simulation schematic diagrams of multi-tag recognition in a warehouse entry and exit scenario provided by this application.

[0050] Fig.11 This is another set of simulation schematic diagrams of multi-tag recognition in warehouse entry and exit scenarios provided by this application.

[0051] Fig.12 This application provides an application scenario of multi-label identification in factory shelves.

[0052] Fig.13 This is a set of simulation schematic diagrams of multi-tag identification in factory logistics provided by this application.

[0053] Fig.14 This is another set of simulation schematic diagrams of multi-tag identification in factory logistics provided by this application.

[0054] Fig.15 It is a schematic diagram of the structure of a radio frequency identification device provided in an embodiment of the present application.

[0055] Fig.16 It is a schematic diagram of the structure of another radio frequency identification device provided in an embodiment of the present application.

[0056] Fig.17 It is a structural schematic diagram of another radio frequency identification device provided in an embodiment of the present application.

[0057] Fig.18 It is a structural schematic diagram of another radio frequency identification device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0058] The embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application.

[0059] The terms "first" and "second" and the like in the specification and claims of the present application and the drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device comprising a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products or devices.

[0060] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0061] The terms "component", "module", "system", etc. used in this specification are used to represent computer-related entities, hardware, firmware, a combination of hardware and software, software, or software in execution. For example, a component can be, but is not limited to, a process running on a processor, a processor, an object, an executable file, an execution thread, a program and / or a computer. By way of illustration, both applications running on a computing device and a computing device can be components. One or more components may reside in a process and / or an execution thread, and a component may be located on a computer and / or distributed between two or more computers. In addition, these components may be executed from various computer-readable media having various data structures stored thereon. Components may, for example, communicate through local and / or remote processes according to signals having one or more data packets (e.g., data from two components interacting with another component between a local system, a distributed system and / or a network, such as the Internet interacting with other systems through signals).

[0062] First, some terms in this application are explained to facilitate understanding by those skilled in the art.

[0063] (1) Radio Frequency Identification (RFID) is a type of automatic identification technology that uses radio frequency to perform non-contact two-way data communication and uses radio frequency to read and write recording media (electronic tags or radio frequency cards) to achieve the purpose of identifying targets and exchanging data. Radio frequency identification technology uses radio waves to quickly exchange information and store information without contact, combines wireless communication with data access technology, and then connects to the database system to achieve non-contact two-way communication, thereby achieving the purpose of identification and data exchange, connecting an extremely complex system in series. In the identification system, the reading, writing and communication of electronic tags are achieved through electromagnetic waves. Depending on whether the tag is powered internally, RFID tags are divided into three categories: passive (passive), semi-passive (also called semi-active), and active. Passive tags have the advantages of low price, small size, and no need for power. Currently, passive RFID tags are mainly used in the market.

[0064] (2) Two-point passive RFID consists of a reader and a passive electronic tag. The reader has the functions of transmitting and receiving, which are implemented by the internal transmitter and receiver respectively. The reader uses the same frequency for transmission and reception. When the reader is receiving, the transmitter cannot stop working because it needs to provide energy to the passive tag. The high-power signal emitted by the transmitter will cause great interference to the receiver, causing the receiver to be saturated and unable to normally receive the weak tag reflection signal, affecting the receiver's receiving sensitivity and limiting the distance at which the reader can read the tag.

[0065] (3) Reader / writer is generally considered to be a reader / writer terminal device for radio frequency identification, or RFID. It can not only read radio frequency tags, but also read and write data, so it is called a reader / writer. If it can only read but not erase and write, it is called a card reader or radio frequency identifier. Readers / writers are widely used, mainly in identity recognition, cargo identification, security authentication and data collection, and have the characteristics of security, accuracy, speed, expansion and strong compatibility.

[0066] (4) Electromagnetic waves are oscillating particle waves derived from the same and mutually perpendicular electric and magnetic fields in space. They are electromagnetic fields that propagate in the form of waves and have the dual nature of wave and particle. Electromagnetic waves are caused by the same phase oscillating and mutually perpendicular electric and magnetic fields moving in space in the form of waves. Their propagation direction is perpendicular to the electric field. The speed of electromagnetic waves in a vacuum is fixed, and the speed of electromagnetic waves is the speed of light.

[0067] (5) Electronic Product Code (EPC), EPC coding is a new generation of product coding system launched by the International Barcode Organization. The original product barcode is only a code for product classification, while the EPC code is a 96-bit (binary) coding system that gives each single product a globally unique code. The EPC coding data structure standard is applicable to the information processing and information exchange of products (items, trade items, assets, locations, etc.) and services in all links of the global and domestic logistics supply chain.

[0068] (6) Acknowledgement (ACK), that is, in data communication, a transmission control character sent by the receiving station to the sending station. It indicates that the data sent has been confirmed to be received correctly. The ACK signal is usually an ASCII character, and the ACK signal is different in different protocols. When the sender receives the ACK signal, it can send the next data. If the sender does not receive the signal, then the sender may resend the current data packet or stop transmitting data.

[0069] (7) Harmonics refer to the components that are greater than integer multiples of the fundamental frequency obtained by Fourier series decomposition of periodic non-sinusoidal alternating current quantities. They are usually called high-order harmonics, while the fundamental frequency refers to the component whose frequency is the same as the power frequency (50Hz). The interference of high-order harmonics is a major "public hazard" that affects the quality of power in the current power system. Among them, harmonics with a rated frequency that is an odd multiple of the fundamental frequency are called "odd harmonics", such as the 3rd, 5th, and 7th harmonics; harmonics with a rated frequency that is an even multiple of the fundamental frequency are called "even harmonics", such as the 2nd, 4th, 6th, and 8th harmonics.

[0070] In fact, in the tag frequency division multiplexing scenario, a large number of passive tags are deployed, and the location of the passive tags is either close or far from the activator, and the location of the passive tags is also either far or near from the receiver, so the near-far effect is common in the time deployment scenario. Figure 1 , Figure 1 is a spectrum diagram received by a receiver air interface when a group of 5 labels are frequency-division multiplexed and a corresponding demodulation bit error rate simulation schematic diagram provided in an embodiment of the present application, wherein, Figure 1 As shown in (1), the third tag "ch3" has a large reflected power, and its harmonic energy is greater than the energy reflected by other passive tags, which will seriously affect the demodulation and reception of other passive tags.

[0071] Secondly, if Figure 1As shown in (2), the horizontal axis is the power of the third tag that is stronger than other tags, and the vertical axis is the demodulation bit error rate of each tag. It can be found that when the power difference is larger, the demodulation bit error rate of other tags is larger, while tag 3 has no bit error because of its strongest power. As can be seen from the figure, when the power of ch3 is higher than 8db, the demodulation accuracy of other passive tags begins to decrease. When it reaches more than 20dB, the demodulation BER of other passive tags deteriorates to 20%, and the demodulation performance of the receiver is seriously degraded.

[0072] In summary, in the tag frequency division multiplexing scenario, the tag has no shaping filter, and the reflected waveform has a large number of harmonic components. Due to the near-far effect, the larger harmonic components of the tag will interfere with the demodulation of other tags, resulting in other tags being unable to be counted, and the overall inventory rate is reduced.

[0073] Based on the above-mentioned technical problems and the corresponding application scenarios in this application, and also to facilitate understanding of the embodiments of this application, the following first describes one of the radio frequency identification system architectures based on the embodiments of this application. Figure 2 , Figure 2 Schematic diagram of a radio frequency identification system architecture provided by an embodiment of the present application. Figure 1 As shown, based on the original two-point passive RFID to separate the transmitter and receiver in the reader, the radio frequency identification system architecture in this application may include Figure 2 The receiver (Receiver) 001, the stimulator (Helper) 002 and the passive tag (Tag) 003, wherein the passive tag Tag003 carries its own tag identification ID information by reflecting the electromagnetic waves emitted by the stimulator 002, and the receiver 001 demodulates the reflected signal of the passive tag Tag003 and obtains the tag information of the passive tag to complete the tag recognition process.

[0074] Receiver 001 is equivalent to the receiver in the reader, such as Figure 2As shown, the receiver is mainly composed of a transmitting module, a receiving module, and a control module. The control module encodes and modulates the instruction content of the control exciter, generates the baseband waveform to be sent (i.e., electromagnetic wave), and determines the time to send the baseband waveform; the transmitting module is responsible for up-converting the baseband waveform and transmitting it through the transmitting antenna; the receiving module is used to receive the reflected signal reflected back by the tag based on the modulated baseband signal through the receiving antenna. For example, the excitation signal can be transmitted to the exciter through frequency 1. For another example: Receiver 001 can receive a first reflected signal reflected by a passive tag based on a single-tone signal, where the passive tag is any one of a plurality of passive tags, and the single-tone signal is a signal with only one frequency; demodulate the first reflected signal to obtain a flipping moment of the first reflected signal; obtain a non-constant envelope signal by non-constantly modulating the single-tone signal, and transmit the non-constant envelope signal to the passive tag after a delay of a target time period, wherein a trough of the non-constant envelope signal after transmission is aligned with the flipping moment of the first reflected signal; receive a second reflected signal reflected by the passive tag based on the non-constant envelope signal; demodulate the second reflected signal to obtain tag information corresponding to the passive tag, wherein the tag information includes a tag identifier.

[0075] The exciter (Helper) 002 is equivalent to the transmitter in the reader / writer. The exciter is mainly composed of a frequency shift module, in which, after receiving the baseband waveform transmitted by the receiver through the receiving antenna, the frequency shift module performs frequency shift transmission to activate the tag. For example: after the exciter receives the excitation signal (that is, the baseband waveform signal transmitted by the receiver, which can provide energy for the passive tag), it can perform frequency shift forwarding and forward it to the passive tag through frequency point 2. It should be noted that the receiver (Receiver) 001 and the exciter (Helper) 002 together are equivalent to the reading and writing device of the radio frequency tag. The reading and writing device and the radio frequency tag must use the spatial channel to realize the reader / writer sending commands to the radio frequency tag. After receiving the command from the reader / writer, the radio frequency tag makes the necessary response, thereby realizing radio frequency identification.

[0076] Passive tag (Tag) 003, after being activated and receiving a special command, reflects the internally stored information such as the Electronic Product Code (EPC). Figure 1As shown in the figure, a passive tag can be composed of an antenna, a reflection switch, an RF-DC conversion circuit, detection, digital processing, and a reflection impedance Zm, among which the RF-DC conversion circuit module is used to complete energy collection and is responsible for supplying energy to other modules. After the digital processing module obtains energy, it generates a "0101" bit stream baseband signal according to the internally stored identification ID information to control the reflection of the reflection switch. When the baseband signal is "0", the reflection switch is closed, and the electromagnetic wave is absorbed by the matching resistor Zm. At this time, due to impedance matching, the electromagnetic wave received by the antenna will be absorbed by Zm, and the tag does not reflect the electromagnetic wave to the air interface; when the baseband signal is "1", the switch is opened, the antenna is open, and the impedance is not matched. Therefore, the received electromagnetic wave is reflected to the air interface by the open circuit. Through reflection and non-reflection, the energy in the air interface is sometimes present and sometimes absent, so that the ID information itself is transmitted to the air interface. The entire reflection process belongs to OOK (On-off keying) modulation. Since OOK modulation controls the switch on and off to form energy changes, the energy changes directly between on and off, and the change is very steep, which will form strong harmonics from the spectrum. Figure 3 , Figure 3 is a time domain and spectrum of a square wave signal provided in an embodiment of the present application, wherein the expression of the square wave signal is: like Figure 3 As shown in the figure, according to the expression, it can be found that the square wave has 2n+1 odd-order harmonics, and the amplitude of the harmonics is 1 / (2n+1). Please refer to the attached Figure 4 , Figure 4 FIG. 1 is a simulation diagram of a passive tag reflection signal provided in an embodiment of the present application. Figure 4 As shown in the figure, the baseband signal reflected by the passive tag is the bit stream (bit stream) of the tag identification ID of the passive tag itself after Miller and FM0 encoding. It is also a rectangular wave similar to the square wave. It can be found that the spectrum characteristics of the passive tag reflection signal are similar to the square wave. There are 2n+1 odd harmonics in the wave, and the amplitude of the harmonics is also 1 / (2n+1).

[0077] It should be noted that the entire RFID system is controlled by the receiver, the exciter only performs frequency shift forwarding and does not actively transmit, and the passive tag is controlled by the waveform transmitted by the exciter, that is, it is indirectly controlled by the receiver. Among them, the passive tag signal strength received by the receiver is determined by the two links of exciter-passive tag and passive tag-receiver. The received passive tag signal power = exciter transmission power-Loss1-passive tag reflection loss-Loss2, where Loss1 represents the path loss from the exciter to the passive tag, and Loss2 represents the path loss from the passive tag to the receiver. When the distance between the passive tag and the exciter and the receiver is different, the power of the passive tags received at different frequencies will be different, and the strong signal harmonics will affect the weak signal reception, forming a near-far effect. Since the passive tag can only passively reflect and cannot determine the power strength received by the receiver, if you want to perform power control so that the receiver receives the same power as the passive tag, you must perform power control on the exciter. If the power of the received passive tag is large, the transmission power of the corresponding exciter is reduced, thereby reducing the harmonic power of the received passive tag, thereby reducing interference to passive tags at other frequencies and alleviating the near-far effect.

[0078] Therefore, the receiver transmits the excitation signal to the exciter through frequency 1. After receiving the excitation signal, the exciter performs frequency shift forwarding and forwards it to the passive tag through frequency 2. The passive tag receives the signal of frequency 2 to complete its own charging and reflects its own tag information to the receiver at frequency 2. The receiver receives the tag reflection signal and demodulates the flipping moment of the passive tag, where the flipping moment is the moment when the rising edge and falling edge of the signal reflected back by the passive tag alternate. Finally, the reflection signal of the passive tag based on the non-constant envelope signal is received, and the demodulation is completed to finally obtain the tag information of the passive tag, realizing the inventory operation of the passive tag. Due to the physical separation and frequency separation of transmission and reception, the transmission and reception of the receiver are different frequencies, thereby solving the receiver saturation problem and increasing the distance of the receiver reading the tag.

[0079] Understandably, Figure 2 The RFID system architecture in the embodiment of the present application is only an exemplary implementation, and the RFID system architecture in the embodiment of the present application includes but is not limited to the above RFID system architecture. For example: the exciter can also forward the excitation signal to multiple passive tags respectively.

[0080] based on Figure 2 The provided RFID system architecture, combined with the RFID method provided in this application, specifically analyzes and solves the technical problems raised in this application.

[0081] See also Figure 5 , Figure 5 is a flow chart of a radio frequency identification method provided in an embodiment of the present application, which can be applied to the above Figure 2 In the radio frequency identification system architecture described in the above, the receiver 001 can be used to support and execute Figure 5 The method flow shown in steps S501, steps S503-step S505 and steps S507-step S508; the actuator 002 can be used to support and execute Figure 5 The method flow steps S502 and S506 shown in FIG. Figure 5 The method is described from the interaction between the receiver 001 and the exciter 002. The method may include the following steps S501 to S508.

[0082] Step S501: The receiver transmits a single tone signal to the exciter.

[0083] Specifically, the receiver transmits the single-tone signal to the exciter, wherein the exciter is any one of the M exciters, and the exciter is used to forward the single-tone signal to the corresponding N passive tags, and the single-tone signal is a signal with only one frequency, and the N passive tags are N of the multiple passive tags, M is a positive integer greater than 1, and N is a positive integer greater than or equal to 1. It should be noted that the single-tone signal can be understood as a single-frequency signal, that is, the signal contains only one frequency and no other frequency components. Secondly, the single-tone signal can also be understood as a single-carrier frequency continuous wave with a constant envelope. It should also be noted that the receiver can simultaneously send the single-tone signal to each exciter in the multiple exciters, and each exciter forwards or frequency-shifts the single-tone signal to one or more passive tags corresponding to it. In addition, the receiver can simultaneously transmit the single-tone signal to M exciters, so that the M exciters respectively remember the corresponding passive tags to forward the single-tone signal.

[0084] Step S502: the exciter forwards the single tone signal to the corresponding passive tag.

[0085] Specifically, the exciter forwards a single-tone signal to the corresponding passive tag, that is, the exciter can simultaneously forward a single-carrier continuous wave (single-tone signal) to one or more corresponding passive tags in a frequency-shifted manner, so that the frequency of each passive tag is different, and thus the receiver saturation problem is greatly alleviated due to the physical separation and frequency separation of transmission and reception, and the distance for reading tags is increased. It should be noted that in the embodiment of the present application, there can be multiple exciters at the same time, and each of the multiple exciters can forward an excitation signal to its corresponding passive tag, such as a single-tone signal, a non-constant envelope signal, etc.

[0086] Step S503: The receiver receives the first reflected signal.

[0087] Specifically, the receiver receives a first reflected signal, which is a signal reflected by the passive tag based on the single-tone signal. The passive tag is any one of a plurality of passive tags, and each of the plurality of passive tags reflects the single-tone signal forwarded by the exciter to the receiver.

[0088] Step S504: the receiver demodulates the first reflected signal to obtain a flipping moment of the first reflected signal.

[0089] Specifically, the receiver demodulates the first reflected signal to obtain the flipping moment of the first reflected signal corresponding to the passive tag. It should be noted that the flipping moment can be understood as the moment when the rising edge and the falling edge in the first reflected signal alternate. For example: in the passive tag reflection stage (such as RN16, EPC stage), the receiver first transmits a single-carrier continuous wave according to the protocol. After the exciter frequency-shifts and forwards the single-carrier continuous wave, the receiver demodulates the signal header reflected by the received passive tag according to the protocol and estimates the moment when the passive tag reflection signal flips. Please refer to the attached Figure 6 , Figure 6 This is a typical signaling flow chart of a 6C protocol change inventory provided in an embodiment of the present application. Among them, RFID has multiple protocols, and the most widely used is the ISO / IEC 18000--6C standard formulated by the EPC organization, referred to as the 6C protocol. The 6C protocol specifies the protocol interaction standard between the reader and the tag. The reader counts the passive tag, that is, the process of reading the passive tag's own ID. In the embodiment of the present application, Figure 6 The receiver transmits Select, Query and other commands (transmitted by a single-tone signal) in sequence through the exciter, and the passive tag reflects the RN16 command. The receiver demodulates the RN16 and transmits the confirmation character ACK and other commands (transmitted by a non-constant signal). The passive tag replies with the electronic product code EPC (i.e., the tag ID of the passive tag). The receiver demodulates the signal reflected back by the passive tag and reads the EPC to complete the inventory of the tag.

[0090] Optionally, the demodulation of the first reflected signal and the acquisition of the flipping moment of the first reflected signal include: if the first reflected signal includes part or all of the tag information, demodulating the first reflected signal reflected by the passive tag to obtain the initial reflection moment and period of the first reflected signal; according to the initial reflection moment and period of the first reflected signal, the flipping moment of the first reflected signal is acquired. It should be noted that if it is detected that the first reflected signal includes part or all of the tag information, it can be proved that the passive tag can normally reflect the single-tone signal or the non-constant envelope signal, and then the received reflected signal can be demodulated. If it is not detected that the tag starts to reflect part or all of the tag information, it is necessary to wait in the current state to reduce the error rate of reading the passive tag. Among them, the tag information may include a 16-bit random number (Random number 16, Rn16) of a passive tag, an electronic product code (Electronic Product Code, Epc) or a tag identifier of a passive tag, etc. It should also be noted that the first reflected signal demodulated by the receiver is to determine the flipping moment of the passive tag reflected signal, and is not used to demodulate the tag information (tag identification, etc.) of the passive tag to improve the inventory rate of the passive tag.

[0091] Step S505: the receiver obtains a non-constant envelope signal by performing non-constant modulation on the single tone signal, and transmits the non-constant envelope signal to the exciter after delaying the target time period.

[0092] Specifically, the receiver modulates the single-tone signal non-constantly to obtain a non-constant envelope signal, and transmits the non-constant envelope signal to the exciter after delaying the target time period, wherein the trough of the non-constant envelope signal after transmission is aligned with the flipping moment of the first reflected signal. Because when the excitation signal is a non-constant envelope signal, at the moment of the passive tag OOK modulation reflection, the intensity of the excitation signal can be greatly weakened, so that the signal energy reflected by the tag is gradually weakened, the steep edge is smoothed, and harmonics can be suppressed. Therefore, in order to achieve a better suppression effect on the harmonics reflected by the passive tag, the single-tone signal can be non-constantly modulated into a non-constant envelope signal by the receiver, and the non-constant envelope signal is transmitted to multiple exciters after delaying the target time period, wherein the trough of the non-constant envelope signal after transmission is aligned with the flipping moment of the first reflected signal corresponding to each passive tag. For example, the edge of the passive tag reflection signal is aligned with the "stop" point of the carrier energy, so that the waveform reflected by the passive tag is consistent with the waveform after active shaping filtering, so as to achieve the purpose of suppressing harmonics. For example, after the passive tag starts reflecting, the first reflected signal is demodulated, the high and low level switching moment (the flipping moment in the embodiment of the present application) is estimated, the stop moment of the start and stop carrier is aligned, and it can be continuously iterated and corrected in subsequent reception. Among them, the passive tag reflection stage refers to all stages when the passive tag starts backscattering, including the reflection of Rn16 and EPC, as well as the reflection of Tid, UserId and other stages. Moreover, the confirmation of these reflection stages can be achieved through the above Figure 6 The air interface signaling shown performs phase identification.

[0093] Optionally, the non-constant modulation of the single-tone signal into a non-constant envelope signal, and the transmission of the non-constant envelope signal to the passive tag after a delay of a target time period, includes: after the non-constant modulation of the single-tone signal into the non-constant envelope signal, the transmission of the non-constant envelope signal to the passive tag starts at time t1+n*T-t2, wherein n is the smallest integer that makes n*T-t2>0, t1 is the initial reflection time of the first reflected signal, t2 is the transmission time for the receiver to transmit the single-tone signal to the exciter, T is the period of the first reflected signal, and the exciter may correspond to one or more passive tags. It should be noted that it takes a certain amount of time for the signal to pass from the receiver to the exciter and then be forwarded from the exciter to the passive tag. Therefore, if you want to align the trough of the non-constant envelope signal after transmission with the flipping moment of the first reflected signal corresponding to each passive tag, it is necessary to delay the transmission of the modulated non-constant envelope signal for a certain amount of time. For example: Please refer to the attached Figure 7 , Figure 7 is a schematic diagram of the timing relationship between a receiver, an exciter, and a passive tag provided in an embodiment of the present application, such as Figure 7As shown, t2 is the transmission time of the single tone signal emitted to the exciter, T is the period of the first reflected signal, and t1 is the initial reflection time of the first reflected signal. Among them, for passive tags, the tag itself does not have "active" shaping and filtering capabilities, that is, the tag cannot emit a non-constant envelope waveform and can only passively reflect the incident electromagnetic wave. If the incident electromagnetic wave is a waveform after shaping and filtering (non-constant envelope), then the tag will also be a non-constant envelope waveform after passive reflection, thereby achieving the effect of actively emitting a non-constant envelope waveform.

[0094] Optionally, the trough of the non-constant envelope signal after transmission is aligned with the flipping moment of the first reflected signal, including: the period of the non-constant envelope signal after transmission is within a preset period range, and the deviation between the trough of the non-constant envelope signal after transmission and the rising edge or falling edge of the first reflected signal does not exceed X*2÷f blf , the preset period range is: from (1-X)*2÷f blf to (1+X)*2÷f blf , that is, it can be understood as: (1+X)*2÷f blf >Period(s)>(1-X)*2÷f blf , where X is the preset error threshold, f blf is the reflection link frequency of the first reflection signal. As long as the transmitted carrier is in the form of a non-constant envelope, and the deviation between the rising edge or falling edge of the non-constant envelope signal and the passive tag reflection signal does not exceed the preset error threshold, it can be considered that the trough of the non-constant envelope signal is aligned with the tag reflection signal, and therefore, the tag can be suppressed from generating a large number of harmonics, thereby suppressing harmonic interference. For example: X can be set to 5%, that is, the period of the non-constant envelope signal after transmission is 1.05*2÷f ｂlf >Period of non-constant envelope signal (s)>0.95*2÷f blf The deviation between the trough of the non-constant envelope signal after transmission and the rising edge or falling edge of the first reflected signal does not exceed 0.05*2÷f blf It should be noted that the embodiment of the present application does not specifically limit the size of X.

[0095] Optionally, the envelope form of the non-constant modulation is: evp=abs(cos(2πf blf t)); or, evp = 1-abs(cos(2πf blf t)), where f blfis the reflection link frequency of the first reflection signal. Since the passive tag Tag reflection baseband signal is the bit stream (bit stream) of the tag identification ID of the passive tag itself after Miller and FM0 encoding, it is also a rectangular wave similar to the square wave. It can be found that the spectrum characteristics of the passive tag Tag reflection signal are similar to the square wave. Therefore, different forms of non-constant envelope signals have different parts of the reflected harmonics (i.e., the second reflection signal) that are enhanced. When the envelope form of the non-constant modulation is evp=abs(cos(2πf blf t)), the third harmonic can be greatly enhanced. When the envelope of the non-constant modulation is evp=1-abs(cos(2πf blf t)), the harmonics after the third are mainly enhanced. Therefore, different forms of envelope waveforms enhance different parts of harmonics, and the form of non-constant modulation envelope can be flexibly selected according to actual needs to enhance the accuracy of reading passive tags.

[0096] Step S506: the exciter forwards the non-constant envelope signal to the corresponding passive tag.

[0097] Specifically, the exciter forwards the non-constant envelope signal to the corresponding passive tag. That is, the exciter can frequency-shift forward the carrier signal (non-constant envelope signal) after non-constant modulation to the corresponding one or more passive tags to weaken the intensity of the excitation signal, so that the signal energy reflected by the tag is gradually weakened, the steep edge is smoothed, and the harmonics can be suppressed. It can be understood that each of the multiple exciters can simultaneously forward the non-constant envelope signal to the corresponding passive tag, and each exciter can correspond to multiple passive tags.

[0098] Step S507: the receiver receives the second reflected signal.

[0099] Specifically, the receiver receives a second reflected signal, wherein the second reflected signal is a signal reflected by each passive tag based on the non-constant envelope signal, and the tag information includes a tag identifier.

[0100] Step S508: The receiver demodulates the second reflected signals respectively corresponding to the plurality of passive tags to obtain the tag information respectively corresponding to the plurality of passive tags.

[0101] Specifically, the receiver demodulates the second reflected signals corresponding to the plurality of passive tags to obtain tag information corresponding to the plurality of passive tags, wherein the tag information includes a tag identifier, a tag type, and information about an item corresponding to the tag, etc., which is not specifically limited in the embodiment of the present application.

[0102] Therefore, in order to achieve a better suppression effect on the harmonics reflected by the passive tag, the embodiment of the present application can be implemented to first demodulate the reflected signal based on the single-tone signal to obtain the flipping moment of the passive tag. Then, a non-constant envelope waveform is emitted through non-constant modulation, so that the trough (energy minimum point) of the waveform is aligned with the flipping moment of the passive tag reflected signal, so that the waveform reflected by the passive tag is also a non-constant envelope signal, that is, the signal reflected by the passive tag is formed and filtered, and the purpose of suppressing harmonics is achieved. The present application reduces the influence of the near-far effect and improves the reading rate of the label in the frequency division multiplexing scenario. Secondly, the cause of the harmonics reflected by the label is that the excitation signal is a single-tone signal (i.e., a signal with only one frequency), and the label performs OOK modulation (switch modulation) reflection on it, generating steep rising and falling edges, and containing rich harmonic components. As for passive tags, the tags themselves do not have "active" shaping and filtering capabilities and can only passively reflect incident electromagnetic waves. Therefore, by incident non-constant envelope signals, at the moment of tag OOK modulation reflection, the intensity of the excitation signal can be weakened, so that the signal energy reflected by the tag gradually weakens, thereby achieving the effect of shaping filtering to suppress harmonics.

[0103] based on Figure 2 The RFID system architecture provided, as well as the above Figure 5 The radio frequency identification method provided below provides two typical application scenarios under different forms of non-constant modulation. Both of the two application scenarios have tag harmonic interference caused by the near-far effect.

[0104] Scenario 1: Multiple entry and exit scenarios.

[0105] Please refer to the attached Figure 8 , Figure 8 This application provides an application scenario of multi-tag identification in factory logistics. Figure 8 As shown in the figure, in a typical scenario in factory logistics, trucks enter and exit through multiple parallel crossings, and multiple forklifts load and unload goods at multiple crossings. A passive RFID system is needed to count and monitor the goods entering and leaving the warehouse to ensure that 100% of the goods entering and leaving the warehouse are automatically recorded without omission.

[0106] The exciter is deployed on the gate of the crossing, the passive tag is deployed on the surface of the cargo on the forklift, and the receiver is deployed 50m opposite the central crossing. Generally, the passive tag is 1m to 10m away from the exciter, and the Loss1 of different passive tags differs by 0 to 20dB. The passive tag is 50m to 100m away from the receiver, and the Loss2 of different passive tags differs by 0 to 6dB. The near-far effect causes the power difference between different passive tags to be 0 to 26dB. Among them, Loss1 represents the path loss from the exciter to the passive tag, and Loss2 represents the path loss from the passive tag to the receiver.

[0107] Therefore, please refer to the attached Fig. 9 , Fig. 9 This is a flow chart of the radio frequency identification method in the multi-entry scene provided by this application, such as Fig. 9 As shown, the embodiment of the present application can implement the following steps 1-5:

[0108] 1. The receiver sends a Query command, and the actuator forwards it. For example: the receiver sends a command (such as Select, Query) according to the protocol, and the actuator forwards the command.

[0109] 2. The receiver sends a single carrier frequency continuous wave. For example, in the passive tag reflection stage (such as RN16), the receiver first transmits a single carrier frequency continuous wave according to the protocol, and the exciter frequency shifts and forwards the single carrier frequency continuous wave.

[0110] 3. The receiver receives the reflected signal from the passive tag and demodulates it, estimates the period and time of the reflected signal from the passive tag, and calculates the delay time. For example, demodulate the signal header reflected by the passive tag according to the protocol, and estimate the time and period of the flip of the reflected signal from the passive tag.

[0111] 4. The receiver delays a certain period of time to send a non-continuous wave (start-stop carrier) to align with the passive tag reflection signal. For example: delay a period of time to transmit a non-constant envelope carrier, the exciter frequency-shifts and forwards the carrier, and the receiver delays the time to align the non-constant envelope carrier forwarded by the exciter with the period of the passive tag reflection.

[0112] 5. The receiver continues to demodulate the remaining part of the passive tag reflection and sends subsequent commands according to the protocol. In any subsequent passive tag reflection phase (such as the reflection EPC phase), steps 3 and 4 are repeated until the passive tag reflection ends.

[0113] For the inbound and outbound scenarios, the non-constant envelope form is evp=abs(cos(2πf blf Please refer to the attached Fig.10 , Fig.10 This is a set of simulation diagrams of multi-tag recognition in a warehouse entry and exit scenario provided by this application. Fig.10 As shown in (1) and (2), the simulation conditions are 5 channels of frequency division multiplexing, with an interval of 500k, the tag's reflection link frequency blf = 125k, M2, and the passive tag ch1 / 2 / 4 / 5 have equal power. The simulated ch3 power is stronger than the BER of each channel under different values ​​of other channels. Fig.10 Before the implementation of the present application embodiment, as shown in (1), the horizontal axis is the power of the third tag being stronger than that of other tags, and the vertical axis is the demodulation bit error rate of each tag. It can be found that when the power difference is larger, the demodulation bit error rate of other tags is larger, while tag 3 has no bit error because of its strongest power. Fig.10After implementing the embodiment of the present application as shown in (2), from the comparison before and after implementation, the bit error rate curve after the implementation of the present application has a benefit of about 18dB.

[0114] For the inbound and outbound scenarios, the non-constant envelope form is evp=1-abs(cos(2πf blf Please refer to the attached Fig.11 , Fig.11 This is another set of simulation diagrams of multi-tag recognition in a warehouse entry and exit scenario provided by this application. Fig.11 As shown in (1) and (2), the simulation conditions are 5 channels of frequency division multiplexing, with an interval of 500k, the tag's reflection link frequency blf = 125k, M2, ch1 / 2 / 4 / 5 power are equal, and the simulated ch3 power is stronger than the BER of each channel under different values ​​of other channels. Fig.11 Before the implementation of the present application embodiment, as shown in (1), the horizontal axis is the power of the third tag being stronger than that of other tags, and the vertical axis is the demodulation bit error rate of each tag. It can be found that when the power difference is larger, the demodulation bit error rate of other tags is larger, while tag 3 has no bit error because of its strongest power. Fig.11 After implementing the embodiment of the present application as shown in (2), from the comparison before and after implementation, the bit error rate curve after the implementation of the present application has an 8dB benefit.

[0115] Scene 2: Warehouse inventory scene.

[0116] Please refer to the attached Fig.12 , Fig.12 This is an application scenario of multi-label recognition in factory shelves provided by this application. Fig.12 As shown in the figure, in a factory warehouse with multiple shelves, it is necessary to regularly count the items on the shelves.

[0117] The exciter is deployed on the top of each shelf, the passive tag is deployed on the tag of each item on the shelf, and the receiver is deployed on the ceiling in the center of all shelves. Generally, the passive tag is 0.1m to 5m away from the exciter, and the Loss1 of different passive tags varies by 0 to 34dB. The passive tag is 10m to 100m away from the receiver, and the Loss2 of different passive tags varies by 0 to 20dB. The near-far effect causes the power difference between different passive tags to be 0 to 54dB. Among them, Loss1 represents the path loss from the exciter to the passive tag, and Loss2 represents the path loss from the passive tag to the receiver.

[0118] It should be noted that the method flow of radio frequency identification can be found in the above Fig. 9 The relevant description of the method flow shown is not repeated in the embodiments of the present application.

[0119] For the warehouse inventory scene, the non-constant envelope form is evp = abs(cos(2πfblf For simulation of t)), please refer to the attached Fig.13 , Fig.13 This application provides a set of simulation diagrams of multi-tag identification in factory logistics. Fig.13 As shown in (1) and (2), the simulation conditions are 5 channels of frequency division multiplexing, with an interval of 500k, the tag's reflection link frequency blf = 62.5k, M2, ch1 / 2 / 4 / 5 power are equal, and the simulated ch3 power is stronger than the BER of each channel under different values ​​of other channels. Fig.13 Before the implementation of the present application embodiment, as shown in (1), the horizontal axis is the power of the third tag being stronger than that of other tags, and the vertical axis is the demodulation bit error rate of each tag. It can be found that when the power difference is larger, the demodulation bit error rate of other tags is larger, while tag 3 has no bit error because of its strongest power. Fig.13 After implementing the embodiment of the present application as shown in (1), from the comparison before and after implementation, the bit error rate curve after the implementation of the present application has a 20+dB benefit.

[0120] For the warehouse inventory scene, the non-constant envelope form is evp = 1-abs(cos(2πf blf For simulation of t)), please refer to the attached Fig.14 , Fig.14 This is another set of simulation schematic diagrams of multi-tag recognition in factory logistics provided by this application. Fig.14 As shown in (1) and (2), the simulation conditions are 5 channels of frequency division multiplexing, with an interval of 500k, the tag's reflection link frequency blf = 62.5k, M2, ch1 / 2 / 4 / 5 power are equal, and the simulated ch3 power is stronger than the BER of each channel under different values ​​of other channels. Fig.14 Before the implementation of the present application embodiment, as shown in (1), the horizontal axis is the power of the third tag being stronger than that of other tags, and the vertical axis is the demodulation bit error rate of each tag. It can be found that when the power difference is larger, the demodulation bit error rate of other tags is larger, while tag 3 has no bit error because of its strongest power. Fig.14 After implementing the embodiment of the present application as shown in (1), from the comparison before and after implementation, the bit error rate curve after the implementation of the present application has a 25+dB benefit.

[0121] The method of the embodiment of the present application is described in detail above, and the related device of the embodiment of the present application is provided below.

[0122] See also Fig.15 , Fig.151 is a schematic diagram of the structure of a radio frequency identification device provided in an embodiment of the present application. The radio frequency identification device 10 may include a first receiving unit 101, a first demodulation unit 102, a modulation unit 103, a second receiving unit 104 and a second demodulation unit 105, and may also include a transmitting unit 106, wherein each unit is described in detail as follows.

[0123] A first receiving unit 101 is used to receive a first reflected signal reflected by a passive tag based on a single-tone signal, wherein the passive tag is any one of a plurality of passive tags, and the single-tone signal is a signal having only one frequency;

[0124] A first demodulation unit 102, configured to demodulate the first reflected signal to obtain a flipping moment of the first reflected signal;

[0125] The modulation unit 103 is used to obtain a non-constant envelope signal by non-constant modulation of the single tone signal, and transmit the non-constant envelope signal to the passive tag after a delay of a target time period, wherein the trough of the non-constant envelope signal after transmission is aligned with the flipping time of the first reflected signal;

[0126] A second receiving unit 104 is used to receive a second reflected signal reflected by the passive tag based on the non-constant envelope signal;

[0127] The second demodulation unit 105 is configured to demodulate the second reflected signal to obtain tag information corresponding to the passive tag, where the tag information includes a tag identifier.

[0128] In one possible implementation, the first reflected signal includes part or all of the tag information; the first demodulation unit 102 is specifically used to demodulate the first reflected signal reflected by the passive tag to obtain the initial reflection moment and period of the first reflected signal; and obtain the flipping moment of the first reflected signal according to the initial reflection moment and period of the first reflected signal.

[0129] In one possible implementation, the modulation unit 103 is specifically used to: after non-constantly modulating the single-tone signal into the non-constant envelope signal, start transmitting the non-constant envelope signal to the passive tag at time t1+n*T-t2, wherein n is the smallest integer that makes n*T-t2>0, t1 is the initial reflection time of the first reflected signal, t2 is the transmission time for transmitting the single-tone signal to the exciter, T is the period of the first reflected signal, and the exciter is an exciter that forwards the single-tone signal to the passive tag.

[0130] In a possible implementation, the envelope of the non-constant modulation is in the form of: evp = abs(cos(2πf blft)); or, evp = 1-abs(cos(2πf blf t)), where f blf is the reflection link frequency of the first reflected signal.

[0131] In a possible implementation, the modulation unit 103 is specifically used to: the period of the non-constant envelope signal after transmission is within a preset period range, and the deviation between the trough of the non-constant envelope signal after transmission and the rising edge or falling edge of the first reflected signal does not exceed X*2÷f blf , the preset period range is: from (1-X)*2÷f blf to (1+X)*2÷f blf , where X is the preset error threshold, f blf is the reflection link frequency of the first reflected signal.

[0132] In one possible implementation, the device also includes: a transmitting unit 106, used to transmit the single-tone signal to an exciter, wherein the exciter is used to forward the single-tone signal to the passive tag, the passive tag is one of N passive tags corresponding to the exciter, the N passive tags are N of the multiple passive tags, and N is a positive integer greater than 1.

[0133] It should be noted that the functions of the various functional units in the RFID device 10 described in the embodiment of the present application can be referred to in the above Figure 5 The descriptions of step S501, step S503-step S505, and step S507-step S508 of the method flow shown in the figure are not repeated here.

[0134] See also Fig.16 , Fig.16 It is a structural schematic diagram of another radio frequency identification device provided in an embodiment of the present application. The radio frequency identification device 20, applied to an exciter, may include a single-tone unit 111, a first forwarding unit 112, a non-constant envelope unit 113 and a second forwarding unit 114, wherein each unit is described in detail as follows.

[0135] A single tone unit 111, used to receive a single tone signal sent by a receiver, wherein the single tone signal is a signal having only one frequency;

[0136] A first forwarding unit 112, configured to forward the single tone signal to corresponding multiple passive tags, wherein the passive tag is one of N passive tags corresponding to the exciter, and the N passive tags are N of the multiple passive tags, where N is a positive integer greater than 1;

[0137] A non-constant envelope unit 113, configured to receive a non-constant envelope signal sent by the receiver after a target delay period, wherein the non-constant envelope signal is a signal obtained by non-constant modulation of the single tone signal, and a trough of the non-constant envelope signal is aligned with a flipping moment of the first reflected signal;

[0138] The second forwarding unit 114 is configured to forward the non-constant envelope signal to the passive tag.

[0139] In one possible implementation, the non-constant envelope unit 113 is specifically used to: receive the non-constant envelope signal sent by the receiver at time t1+n*T-t2, wherein n is the smallest integer that makes n*T-t2>0, t1 is the initial reflection moment of the first reflection signal, t2 is the transmission time for the receiver to transmit the single-tone signal to the exciter, T is the period of the first reflection signal, the first reflection signal is the signal reflected by the passive tag based on the single-tone signal, the initial reflection moment is the initial reflection moment of the first reflection signal obtained after the receiver demodulates the first reflection signal, and the period is the period of the first reflection signal obtained after the receiver demodulates the first reflection signal.

[0140] It should be noted that the functions of the various functional units in the RFID device 20 described in the embodiment of the present application can be found in the above Figure 5 The relevant descriptions of step S502 and step S506 of the method flow shown in are not repeated here.

[0141] like Fig.17 As shown, Fig.17 3 is a schematic diagram of the structure of another radio frequency identification device provided in an embodiment of the present application, the device 30 includes at least one processor 201, at least one memory 202, and at least one communication interface 203. In addition, the device may also include common components such as an antenna, which will not be described in detail here.

[0142] The processor 201 may be a general purpose central processing unit (CPU), a microprocessor, an application-specific integrated circuit (ASIC), or one or more integrated circuits for controlling the execution of the above program.

[0143] The communication interface 203 is used to communicate with other devices or communication networks, such as a receiving antenna, a transmitting antenna, Ethernet, a radio access network (RAN), a core network, a wireless local area network (WLAN), etc.

[0144] The memory 202 may be a read-only memory (ROM) or other types of static storage devices that can store static information and instructions, a random access memory (RAM) or other types of dynamic storage devices that can store information and instructions, or an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compressed optical disc, laser disc, optical disc, digital versatile disc, Blu-ray disc, etc.), a magnetic disk storage medium or other magnetic storage device, or any other medium that can be used to carry or store the desired program code in the form of instructions or data structures and can be accessed by a computer, but is not limited thereto. The memory may exist independently and be connected to the processor via a bus. The memory may also be integrated with the processor.

[0145] The memory 202 is used to store application code for executing the above solution, and the execution is controlled by the processor 201. The processor 201 is used to execute the application code stored in the memory 202.

[0146] The code stored in the memory 202 can execute the above Figure 5 The provided radio frequency identification method, for example, receives a first reflection signal reflected by a passive tag based on a single-tone signal, the passive tag is any one of a plurality of passive tags, and the single-tone signal is a signal with only one frequency; demodulates the first reflection signal to obtain a flipping moment of the first reflection signal; obtains a non-constant envelope signal by subjecting the single-tone signal to non-constant modulation, and transmits the non-constant envelope signal to the passive tag after a delay of a target time period, wherein a trough of the non-constant envelope signal after transmission is aligned with the flipping moment of the first reflection signal; receives a second reflection signal reflected by the passive tag based on the non-constant envelope signal; and demodulates the second reflection signals corresponding to the plurality of passive tags respectively to obtain tag information corresponding to the plurality of passive tags respectively, wherein the tag information includes a tag identifier.

[0147] It should be noted that the functions of the various functional units in the RFID device 20 described in the embodiment of the present application can be found in the above Figure 5 The descriptions of step S501, step S503-step S505, and step S507-step S508 of the method flow shown in the figure are not repeated here.

[0148] like Fig.18 As shown, Fig.182 is a schematic diagram of the structure of another radio frequency identification device provided in an embodiment of the present application, the device 40 includes at least one processor 211, at least one memory 212, and at least one communication interface 213. In addition, the device may also include common components such as an antenna, which will not be described in detail here.

[0149] The processor 211 may be a general purpose central processing unit (CPU), a microprocessor, an application-specific integrated circuit (ASIC), or one or more integrated circuits for controlling the execution of the above program.

[0150] The communication interface 213 is used to communicate with other devices or communication networks, such as a receiving antenna, a transmitting antenna, Ethernet, a radio access network (RAN), a core network, a wireless local area network (WLAN), etc.

[0151] The memory 212 may be a read-only memory (ROM) or other types of static storage devices that can store static information and instructions, a random access memory (RAM) or other types of dynamic storage devices that can store information and instructions, or an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compressed optical disc, laser disc, optical disc, digital versatile disc, Blu-ray disc, etc.), a magnetic disk storage medium or other magnetic storage device, or any other medium that can be used to carry or store the desired program code in the form of instructions or data structures and can be accessed by a computer, but is not limited thereto. The memory may exist independently and be connected to the processor via a bus. The memory may also be integrated with the processor.

[0152] The memory 212 is used to store application code for executing the above solution, and the execution is controlled by the processor 211. The processor 211 is used to execute the application code stored in the memory 212.

[0153] The code stored in the memory 212 can execute the above Figure 5The provided radio frequency identification method, for example, receives a single-tone signal sent by a receiver, the single-tone signal is a signal with only one frequency; forwards the single-tone signal to corresponding multiple passive tags, the passive tag is one of N passive tags corresponding to the exciter, the N passive tags are N of the multiple passive tags, and N is a positive integer greater than 1; receives a non-constant envelope signal sent by the receiver after a target delay time period, the non-constant envelope signal is a signal obtained by non-constant modulation of the single-tone signal, and the trough of the non-constant envelope signal is aligned with the flipping moment of the first reflected signal; and forwards the non-constant envelope signal to the passive tag.

[0154] It should be noted that the functions of the various functional units in the RFID device 40 described in the embodiment of the present application can be found in the above Figure 5 The relevant descriptions of step S502 and step S506 of the method flow shown in are not repeated here.

[0155] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0156] It should be noted that, for the above-mentioned method embodiments, for the sake of simplicity, they are all expressed as a series of action combinations, but those skilled in the art should be aware that the present application is not limited by the order of the actions described, because according to the present application, some steps may be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily required by the present application.

[0157] In the several embodiments provided in the present application, it should be understood that the disclosed device can be implemented in other ways. For example, the device embodiments described above are only schematic, such as the division of the above-mentioned units, which is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, and the indirect coupling or communication connection of devices or units can be electrical or other forms.

[0158] The units described above as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0159] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0160] If the above-mentioned integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, a server or a network device, etc., specifically a processor in a computer device) to perform all or part of the steps of the above-mentioned methods of each embodiment of the present application. Among them, the aforementioned storage medium may include: U disk, mobile hard disk, magnetic disk, optical disk, read-only memory (Read-Only Memory, abbreviated: ROM) or random access memory (Random Access Memory, abbreviated: RAM) and other media that can store program codes.

[0161] As described above, the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A radio frequency identification method, characterized in that: Applied to a receiver, the method comprises: Receiving a first reflected signal reflected by a passive tag based on a single-tone signal, wherein the passive tag is any one of a plurality of passive tags, and the single-tone signal is a signal having only one frequency; Demodulating the first reflected signal to obtain a flipping moment of the first reflected signal; The single tone signal is subjected to non-constant modulation to obtain a non-constant envelope signal, and the non-constant envelope signal is transmitted to the passive tag after a delay of a target time period, wherein a trough of the non-constant envelope signal after transmission is aligned with a flipping moment of the first reflected signal; receiving a second reflected signal reflected by the passive tag based on the non-constant envelope signal; The second reflected signals respectively corresponding to the plurality of passive tags are demodulated to obtain tag information respectively corresponding to the plurality of passive tags, wherein the tag information includes a tag identifier.

2. The method according to claim 1, characterized in that: The first reflection signal includes part or all of the tag information; and the demodulating the first reflection signal to obtain the flipping moment of the first reflection signal includes: Demodulating the first reflected signal to obtain an initial reflection time and period of the first reflected signal; The flipping moment of the first reflected signal is acquired according to the initial reflection moment and period of the first reflected signal.

3. The method according to claim 2, characterized in that: The non-constantly modulating the single tone signal into a non-constant envelope signal, and transmitting the non-constant envelope signal to the passive tag after a delay of a target time period, comprises: After non-constantly modulating the single-tone signal into the non-constant envelope signal, starting to transmit the non-constant envelope signal to the passive tag at time t1+n*T-t2, wherein n is the smallest integer that makes n*T-t2>0, t1 is the initial reflection time of the first reflected signal, t2 is the transmission time for transmitting the single-tone signal to the exciter, T is the period of the first reflected signal, and the exciter is an exciter that forwards the single-tone signal to the passive tag.

4. The method according to claim 1, characterized in that: The envelope form of the non-constant modulation is: evp = abs(cos(2πf blf t)); or, evp = 1-abs(cos(2πf blf t)), where f blf is the reflection link frequency of the first reflected signal.

5. The method according to claim 1, characterized in that: The trough of the transmitted non-constant envelope signal is aligned with the flipping time of the first reflected signal, comprising: The period of the non-constant envelope signal after transmission is within the preset period range, and the deviation between the trough of the non-constant envelope signal after transmission and the rising edge or falling edge of the first reflected signal does not exceed X*2÷f blf , the preset period range is: from (1-X)*2÷f blf to (1+X)*2÷f blf , where X is the preset error threshold, f blf is the reflection link frequency of the first reflected signal.

6. The method according to any one of claims 1 to 5, characterized in that: The method also includes: transmitting the single-tone signal to an exciter, wherein the exciter is used to forward the single-tone signal to the passive tag, the passive tag is one of N passive tags corresponding to the exciter, the N passive tags are N of the multiple passive tags, and N is a positive integer greater than 1.

7. A method of radio frequency identification, characterized in that: Applied to an exciter, the method comprises: Receiving a single-tone signal sent by a receiver, wherein the single-tone signal is a signal having only one frequency; Forwarding the single tone signal to corresponding multiple passive tags, wherein the passive tag is one of N passive tags corresponding to the exciter, and the N passive tags are N of the multiple passive tags, where N is a positive integer greater than 1; A non-constant envelope signal sent by the receiver after receiving a delayed target time period, wherein the non-constant envelope signal is a signal obtained by non-constant modulation of the single-tone signal, and the trough of the non-constant envelope signal is aligned with the flipping moment of the first reflected signal; the first reflected signal is a signal reflected by the passive tag based on the single-tone signal; The non-constant envelope signal is forwarded to the passive tag.

8. The method according to claim 7, characterized in that: The receiving of the non-constant envelope signal sent by the receiver after the target delay time period includes: Receive the transmitted non-constant envelope signal sent by the receiver at time t1+n*T-t2, wherein n is the smallest integer that makes n*T-t2>0, t1 is the initial reflection moment of the first reflected signal, t2 is the transmission time for the receiver to transmit the single-tone signal to the exciter, T is the period of the first reflected signal, the initial reflection moment is the initial reflection moment of the first reflected signal obtained after the receiver demodulates the first reflected signal, and the period is the period of the first reflected signal obtained after the receiver demodulates the first reflected signal.

9. A radio frequency identification device, characterized in that: Applied to a receiver, the device comprises: A first receiving unit is used to receive a first reflected signal reflected by a passive tag based on a single-tone signal, wherein the passive tag is any one of a plurality of passive tags, and the single-tone signal is a signal having only one frequency; A first demodulation unit, used to demodulate the first reflected signal to obtain a flipping moment of the first reflected signal; A modulation unit, used for obtaining a non-constant envelope signal by non-constant modulation of the single tone signal, and transmitting the non-constant envelope signal to the passive tag after a delay of a target time period, wherein a trough of the non-constant envelope signal after transmission is aligned with the flipping moment of the first reflected signal; A second receiving unit, configured to receive a second reflected signal reflected by the passive tag based on the non-constant envelope signal; The second demodulation unit is used to demodulate the second reflected signal to obtain tag information corresponding to the passive tag, where the tag information includes a tag identifier.

10. The device according to claim 9, characterized in that: The first reflected signal includes part or all of the tag information; the first demodulation unit is specifically configured to: Demodulating the first reflected signal reflected by the passive tag to obtain the initial reflection time and period of the first reflected signal; The flipping moment of the first reflected signal is acquired according to the initial reflection moment and period of the first reflected signal.

11. The device according to claim 10, characterized in that: The modulation unit is specifically used for: After non-constantly modulating the single-tone signal into the non-constant envelope signal, starting to transmit the non-constant envelope signal to the passive tag at time t1+n*T-t2, wherein n is the smallest integer that makes n*T-t2>0, t1 is the initial reflection time of the first reflected signal, t2 is the transmission time for transmitting the single-tone signal to the exciter, T is the period of the first reflected signal, and the exciter is an exciter that forwards the single-tone signal to the passive tag.

12. The device according to claim 9, characterized in that: The envelope form of the non-constant modulation is: evp = abs(cos(2πf blf t)); or, evp = 1-abs(cos(2πf blf t)), where f blf is the reflection link frequency of the first reflected signal.

13. The device according to claim 9, characterized in that: The modulation unit is specifically used for: The period of the non-constant envelope signal after transmission is within the preset period range, and the deviation between the trough of the non-constant envelope signal after transmission and the rising edge or falling edge of the first reflected signal does not exceed X*2÷f blf , the preset period range is: from (1-X)*2÷f blf to (1+X)*2÷f blf , where X is the preset error threshold, f blf is the reflection link frequency of the first reflected signal.

14. The device according to any one of claims 9 to 13, characterized in that: The device also includes: A transmitting unit is used to transmit the single-tone signal to an exciter, wherein the exciter is used to forward the single-tone signal to the passive tag, the passive tag is one of the N passive tags corresponding to the exciter, the N passive tags are N of the multiple passive tags, and N is a positive integer greater than 1.

15. A radio frequency identification device, characterized in that: Applied to an exciter, the device comprises: A single tone unit, used to receive a single tone signal sent by a receiver, wherein the single tone signal is a signal having only one frequency; A first forwarding unit, configured to forward the single tone signal to a corresponding plurality of passive tags, wherein the passive tag is one of N passive tags corresponding to the exciter, and the N passive tags are N of the plurality of passive tags, where N is a positive integer greater than 1; A non-constant envelope unit, used for receiving a non-constant envelope signal sent by the receiver after a delayed target time period, wherein the non-constant envelope signal is a signal obtained by non-constant modulation of the single-tone signal, and the trough of the non-constant envelope signal is aligned with the flipping moment of the first reflected signal; the first reflected signal is a signal reflected by the passive tag based on the single-tone signal; The second forwarding unit is configured to forward the non-constant envelope signal to the passive tag.

16. The device according to claim 15, characterized in that: The non-constant envelope unit is specifically used for: Receive the transmitted non-constant envelope signal sent by the receiver at time t1+n*T-t2, wherein n is the smallest integer that makes n*T-t2>0, t1 is the initial reflection moment of the first reflected signal, t2 is the transmission time for the receiver to transmit the single-tone signal to the exciter, T is the period of the first reflected signal, the initial reflection moment is the initial reflection moment of the first reflected signal obtained after the receiver demodulates the first reflected signal, and the period is the period of the first reflected signal obtained after the receiver demodulates the first reflected signal.

17. A computer storage medium, characterized in that: The computer storage medium stores a computer program, which, when executed by a processor, implements the method described in any one of claims 1 to 6 or 7 to 8.

18. A computer program product, characterized in that The computer program comprises instructions, and when the computer program is executed by a computer, the computer is caused to perform the method according to any one of claims 1-6 or 7-8.

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