CN105978569B

CN105978569B - Radio frequency identification signal processing method, circuit and device and label reader-writer

Info

Publication number: CN105978569B
Application number: CN201610430781.7A
Authority: CN
Inventors: 陈彬; 李雨翔; 张志华; 杨建航
Original assignee: BEIJING HWA-TECH INFORMATION SYSTEM
Current assignee: BEIJING HWA-TECH INFORMATION SYSTEM
Priority date: 2016-06-16
Filing date: 2016-06-16
Publication date: 2020-03-27
Anticipated expiration: 2036-06-16
Also published as: CN105978569A

Abstract

The invention provides a radio frequency identification signal processing method, a circuit, a device and a label reader-writer, wherein the method comprises the following steps: receiving a tag reverse signal sent by a radio frequency identification tag; acquiring signal parameters of direct current components included in the reverse signals of the tags; according to the signal parameter, the direct current component included in the tag reverse signal is eliminated to obtain the target reverse signal, the problem of low receiving sensitivity of the tag reader-writer in the related technology is solved, and the receiving sensitivity of the tag reader-writer is improved.

Description

Radio frequency identification signal processing method, circuit and device and label reader-writer

Technical Field

The invention relates to the field of communication, in particular to a radio frequency identification signal processing method, a radio frequency identification signal processing circuit, a radio frequency identification signal processing device and a tag reader-writer.

Background

Radio Frequency Identification (RFID for short) is a non-contact Identification system, in which a tag reader/writer performs data communication with a tag on an article through electromagnetic coupling to realize automatic Identification of the tagged article.

The tag of the UHF RFID is passive, when the tag communicates with a reader, the tag needs the reader to provide a large and continuous power energy, and the isolation of the antenna or the circulator commonly used at present is only about 25dB, so that a large carrier leakage may occur, for example: sending a 27dBm signal, the tag reader-writer will receive a forward signal about 2dBm, the carrier leaks into the demodulation module, a direct current signal with a large amplitude is generated through demodulation, because the power of a reverse signal returned by the tag is very low, the signal reaching a receiving antenna during normal communication is very small, for example, the distance between the tag reader-writer antenna and the tag is 1 meter, the tag return signal has about-40 dBm, and the tag return signal cannot be effectively amplified after demodulation by the reader-writer under the influence of the forward large signal and the characteristics of an AD converter (the peak value V-pp of a general A/D device is 2V), so that the receiving sensitivity of the tag reader-writer is greatly reduced.

Currently, a mainstream RFID test system is generally implemented by using a radio frequency front end carrier cancellation circuit, fig. 1 is a schematic diagram of a radio frequency front end carrier cancellation circuit according to the related art, and as shown in fig. 1, the radio frequency front end carrier cancellation circuit is composed of a series of circuits such as a coupler 12, an attenuator 14, a phase shifter 16, and a combiner 18. The carrier signal is extracted by the coupler 12, modulated into a signal with the same amplitude and the opposite phase with the carrier leakage signal of the receiving port through amplitude and phase control, and output in a combined way, so that the leakage carrier can be cancelled.

However, the radio frequency front end carrier cancellation circuit adopts a large number of high frequency analog circuits, so that the requirements on circuit design, PCB layout and the like are high, the cost of the radio frequency phase shifter, the phase discriminator and the attenuator is high, and the control precision of the phase and the amplitude of a high frequency signal is difficult to control. In the feedback control process of the simulation system, the response speed is relatively slow, and the adaptability to external space environment changes such as the distance position of a label and the walking of nearby personnel is poor, so that the sensitivity is improved limitedly.

For the problem of low receiving sensitivity of a tag reader-writer in the related art, no effective solution is available at present.

Disclosure of Invention

The embodiment of the invention provides a radio frequency identification signal processing method, a radio frequency identification signal processing circuit, a radio frequency identification signal processing device and a tag reader-writer, and at least solves the problem of low receiving sensitivity of the tag reader-writer in the related technology.

According to an embodiment of the present invention, there is provided a radio frequency identification signal processing method including: receiving a tag reverse signal sent by a radio frequency identification tag; acquiring signal parameters of a direct current component included in the tag reverse signal; and eliminating the direct current component included in the tag reverse signal according to the signal parameter to obtain a target reverse signal.

Optionally, the obtaining the signal parameter of the dc component included in the tag reverse signal includes: sampling the reverse signals of the labels through analog-to-digital conversion to obtain sampling signals; and extracting the phase and the amplitude of the direct current component according to the sampling signal.

Optionally, eliminating the dc component included in the tag reverse signal according to the signal parameter to obtain the target reverse signal includes: generating a feedback signal having the same amplitude and opposite phase to the DC component; and adding the generated feedback signal and the tag reverse signal, and eliminating the direct current component included in the tag reverse signal to obtain the target reverse signal.

Optionally, the receiving the tag reverse signal sent by the radio frequency identification tag includes: receiving a signal sent by the radio frequency identification tag, wherein the signal sent by the radio frequency identification tag carries the tag reverse signal; extracting the tag reverse signal from the signal transmitted by the radio frequency identification tag.

Optionally, the receiving the signal transmitted by the radio frequency identification tag includes: receiving an original signal sent by the radio frequency identification tag; and amplifying the received original signal to a preset range, and taking the amplified signal as the signal sent by the radio frequency identification tag.

Optionally, after the dc component included in the tag reverse signal is eliminated according to the signal parameter to obtain the target reverse signal, the method further includes: and filtering and amplifying the target reverse signal to obtain an amplified target reverse signal.

According to another embodiment of the present invention, there is provided a radio frequency identification signal processing circuit including: the sampling circuit comprises a switching element, a sampling circuit and an adder, wherein a first port of the switching element is connected to a first port of the sampling circuit and a first port of the adder, a second port of the sampling circuit is connected to a second port of the adder, a second port of the switching element is connected to a signal input end, and a third port of the adder is connected to a signal output end; the switch element is used for receiving a label reverse signal sent by the radio frequency identification label; the sampling circuit is used for acquiring signal parameters of direct current components included in the tag reverse signals; the adder is used for eliminating the direct current component included in the tag reverse signal according to the signal parameter to obtain a target reverse signal.

Optionally, the sampling circuit is configured to: sampling the reverse signals of the labels through analog-to-digital conversion to obtain sampling signals; extracting the phase and amplitude of the direct current component according to the sampling signal; generating a feedback signal having the same amplitude and opposite phase to the DC component.

Optionally, the adder is configured to: and adding the generated feedback signal and the tag reverse signal, and eliminating the direct current component included in the tag reverse signal to obtain the target reverse signal.

Optionally, the switching element is configured to: receiving a signal sent by the radio frequency identification tag, wherein the signal sent by the radio frequency identification tag carries the tag reverse signal; extracting the tag reverse signal from the signal transmitted by the radio frequency identification tag.

Optionally, the circuit further comprises: the first operational amplifier is connected between the signal input end and the second port of the switch element, and is used for amplifying the tag reverse signal to a preset range and taking the amplified signal as the tag reverse signal.

Optionally, the circuit further comprises: and the second operational amplifier is connected between the signal output end and the third port of the adder, and is used for filtering and amplifying the target reverse signal to obtain an amplified target reverse signal.

According to another embodiment of the present invention, there is provided a radio frequency identification signal processing apparatus including: the receiving module is used for receiving a label reverse signal sent by the radio frequency identification label; the acquisition module is used for acquiring signal parameters of direct current components included in the tag reverse signals; and the elimination module is used for eliminating the direct current component included in the label reverse signal according to the signal parameter to obtain a target reverse signal.

According to another embodiment of the present invention, there is provided a tag reader/writer including: the radio frequency identification signal processing circuit of any preceding claim.

According to the invention, a label reverse signal sent by a radio frequency identification label is received; acquiring signal parameters of direct current components included in the reverse signals of the tags; according to the technical scheme, the direct current component in the tag reverse signal is eliminated by obtaining the signal parameter of the direct current component in the received tag reverse signal, the target reverse signal is obtained, and the direct current component in the target reverse signal is reduced, so that the receiving sensitivity of the tag reader-writer is improved, and the problem of low receiving sensitivity of the tag reader-writer in the related technology is solved.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the invention without limiting the invention. In the drawings:

fig. 1 is a schematic diagram of a radio frequency front end carrier cancellation circuit according to the related art;

fig. 2 is a block diagram of a hardware structure of a tag reader/writer of a radio frequency identification signal processing method according to an embodiment of the present invention;

FIG. 3 is a flow chart of a method of RFID signal processing according to an embodiment of the present invention;

FIG. 4 is a block diagram of an RFID signal processing circuit according to an embodiment of the present invention;

FIG. 5 is a block diagram of a second embodiment of an RFID signal processing circuit according to the present invention;

FIG. 6 is a block diagram of a RFID signal processing circuit according to an embodiment of the present invention;

FIG. 7 is a block diagram of an RFID signal processing apparatus according to an embodiment of the present invention;

FIG. 8 is a block diagram of a UHF RFID receiving circuit according to an alternative embodiment of the present invention;

FIG. 9 is a schematic diagram of a timing waveform of a demodulated signal in accordance with an alternative embodiment of the invention;

FIG. 10 is a block diagram of an RFID signal processing circuit according to an alternative embodiment of the present invention;

fig. 11 is a schematic diagram of an rfid signal processing circuit according to an alternative embodiment of the present invention.

Detailed Description

The invention will be described in detail hereinafter with reference to the accompanying drawings in conjunction with embodiments. It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.

It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order.

Example 1

The method provided in embodiment 1 of the present application may be implemented in a tag reader/writer, a tag protocol analyzer, or a similar computing device. Taking an example of the tag reader-writer running on the tag reader-writer, fig. 2 is a hardware structure block diagram of the tag reader-writer of the rfid signal processing method according to the embodiment of the present invention, and as shown in fig. 2, the tag reader-writer 20 may include one or more processors 202 (only one is shown in the figure) (the processor 202 may include, but is not limited to, a processing device such as a microprocessor MCU or a programmable logic device FPGA, etc.), a memory 204 for storing data, and a transmission device 206 for a communication function. It will be understood by those skilled in the art that the structure shown in fig. 2 is only an illustration and is not intended to limit the structure of the electronic device. For example, the tag reader 20 may also include more or fewer components than shown in fig. 2, or have a different configuration than shown in fig. 2.

The memory 204 may be used to store software programs and modules of application software, such as program instructions/modules corresponding to the rfid signal processing method in the embodiment of the present invention, and the processor 202 executes various functional applications and data processing by operating the software programs and modules stored in the memory 204, so as to implement the above-mentioned method. Memory 204 may include high speed random access memory, and may also include non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some examples, the memory 204 may further include memory located remotely from the processor 202, which may be connected to the tag reader 20 via a network. Examples of such networks include, but are not limited to, the internet, intranets, local area networks, mobile communication networks, and combinations thereof.

The transmission means 206 is used for receiving or transmitting data via a network. The above-described specific example of the network may include a wireless network provided by a communication provider of the tag reader/writer 20. In one example, the transmission device 206 includes a network adapter (NIC) that can be connected to other network devices through a base station to communicate with the internet. In one example, the transmission device 206 can be a Radio Frequency (RF) module, which is used for communicating with the internet in a wireless manner.

In the present embodiment, a method for processing a radio frequency identification signal is provided, and fig. 3 is a flowchart of a method for processing a radio frequency identification signal according to an embodiment of the present invention, as shown in fig. 3, the flowchart includes the following steps:

step S302, receiving a label reverse signal sent by a radio frequency identification label;

step S304, acquiring signal parameters of direct current components included in the tag reverse signals;

and S306, eliminating the direct current component included in the tag reverse signal according to the signal parameter to obtain a target reverse signal.

Alternatively, the radio frequency identification signal processing method can be applied to the radio frequency tag identification scene without limitation. For example: and the label reader-writer identifies the radio frequency label according to the reverse signal fed back by the radio frequency label.

Alternatively, the rfid signal processing method may be applied to a tag reader, but not limited to: UHF label reader-writer, label protocol analyzer, etc.

Through the steps, receiving a label reverse signal sent by the radio frequency identification label; acquiring signal parameters of direct current components included in the reverse signals of the tags; according to the technical scheme, the direct current component in the tag reverse signal is eliminated by obtaining the signal parameter of the direct current component in the received tag reverse signal, the target reverse signal is obtained, and the direct current component in the target reverse signal is reduced, so that the receiving sensitivity of the tag reader-writer is improved, and the problem of low receiving sensitivity of the tag reader-writer in the related technology is solved.

In this embodiment, the tag reverse signal transmitted by the rfid tag may be obtained, but not limited to, by using dc coupling.

In the present embodiment, the signal parameter of the dc component may include, but is not limited to, a phase of the dc component and/or a magnitude of the dc component.

In this embodiment, the signal parameter of the dc component may be, but is not limited to, acquired by sampling. For example: and sampling the reverse signal of the label through analog-to-digital conversion to obtain a sampling signal, and extracting the phase and the amplitude of the direct current component according to the sampling signal.

In the present embodiment, the dc component included in the tag reversal signal may be, but is not limited to, eliminated by the adder. For example: and generating a feedback signal which is opposite to the phase of the direct current component and has the same amplitude, adding the generated feedback signal and the tag reverse signal, and eliminating the direct current component contained in the tag reverse signal to obtain a target reverse signal.

Alternatively, in the step S302, the tag reverse signal included in the signal transmitted by the radio frequency identification tag may be extracted from the signal. For example: and receiving a signal which is sent by the radio frequency identification tag and carries a tag reverse signal, and extracting the tag reverse signal from the signal sent by the radio frequency identification tag.

Through the steps, the reverse signal of the label can be extracted from the signal sent by the radio frequency identification label, so that the forward signal possibly included in the signal can be filtered, the influence of the forward signal on the reverse signal can be further eliminated, and the receiving sensitivity of the label reader-writer can be improved.

Optionally, the received original signal may be amplified, but not limited to, and the amplified signal is used as a signal transmitted by the radio frequency identification tag. For example: the method comprises the steps of receiving an original signal sent by the radio frequency identification tag, amplifying the received original signal to a preset range (for example, 0-3V), and taking the amplified signal as a signal sent by the radio frequency identification tag.

Through the steps, the original signal can be amplified, and then the direct current component in the amplified signal is eliminated. Therefore, by adopting the scheme, the receiving sensitivity of the tag reader-writer can be further improved.

Optionally, after the step S306, the target inverse signal may be, but is not limited to, filtered and amplified to obtain an amplified target inverse signal. Thus, the receiving sensitivity of the tag reader/writer is improved.

Example 2

In this embodiment, a radio frequency identification signal processing circuit is further provided, and fig. 4 is a block diagram of a structure of a radio frequency identification signal processing circuit according to an embodiment of the present invention, as shown in fig. 4, the radio frequency identification signal processing circuit includes: a switching element 42, a sampling circuit 44 and an adder 46, wherein a first port of the switching element 42 is connected to a first port of the sampling circuit 44 and a first port of the adder 46, a second port of the sampling circuit 44 is connected to a second port of the adder 46, a second port of the switching element 42 is connected to a signal input terminal, and a third port of the adder 46 is connected to a signal output terminal;

the switching element 42 is used for receiving a tag reverse signal transmitted by the radio frequency identification tag; the sampling circuit 44 is configured to obtain a signal parameter of a dc component included in the tag reverse signal; the adder 46 is configured to eliminate a dc component included in the tag reverse signal according to the signal parameter, so as to obtain a target reverse signal.

Optionally, the rfid signal processing circuit may be applied, but not limited, to a radio frequency tag identification scenario. For example: and the label reader-writer identifies the radio frequency label according to the reverse signal fed back by the radio frequency label.

Alternatively, the rfid signal processing circuit may be applied to, but not limited to, a tag reader, for example: UHF label reader-writer, label protocol analyzer, etc.

Through the above circuit, the switching element 42 is used for receiving a tag reverse signal transmitted by the rfid tag; the sampling circuit 44 is configured to obtain a signal parameter of a dc component included in the tag reverse signal; the adder 46 is configured to eliminate a direct current component included in the tag reverse signal according to the signal parameter to obtain a target reverse signal, and thus, according to the above scheme, the direct current component included in the tag reverse signal is eliminated by obtaining the signal parameter of the direct current component included in the received tag reverse signal to obtain the target reverse signal, and the direct current component included in the target reverse signal is reduced, so that the receiving sensitivity of the tag reader is improved, and the problem of low receiving sensitivity of the tag reader in the related art is solved.

Optionally, the sampling circuit 44 is configured to: sampling the reverse signal of the label through analog-to-digital conversion to obtain a sampling signal; extracting the phase and amplitude of the direct current component according to the sampling signal; a feedback signal is generated that is in phase opposition and of the same magnitude as the dc component.

Optionally, the adder 46 is configured to: and adding the generated feedback signal and the tag reverse signal, and eliminating a direct current component included in the tag reverse signal to obtain a target reverse signal.

Optionally, the switching element 42 is for: receiving a signal sent by a radio frequency identification tag, wherein the signal sent by the radio frequency identification tag carries a tag reverse signal; a tag reverse signal is extracted from a signal transmitted from a radio frequency identification tag.

Through the circuit, the reverse signal of the label can be extracted from the signal sent by the radio frequency identification label, so that the forward signal possibly included in the signal can be filtered, the influence of the forward signal on the reverse signal can be further eliminated, and the receiving sensitivity of the label reader-writer can be improved.

Fig. 5 is a block diagram of a second structure of a rfid signal processing circuit according to an embodiment of the present invention, as shown in fig. 5, optionally, the circuit further includes: a first operational amplifier 52, wherein the first operational amplifier 52 is connected between the signal input terminal and the second port of the switching element 42, and the first operational amplifier 52 is configured to amplify the tag reverse signal to a predetermined range, and use the amplified signal as the tag reverse signal.

Through the circuit, the original signal can be amplified, and then the direct current component in the amplified signal is eliminated. Therefore, by adopting the scheme, the receiving sensitivity of the tag reader-writer can be further improved.

Fig. 6 is a block diagram of a third structure of a radio frequency identification signal processing circuit according to an embodiment of the present invention, as shown in fig. 6, optionally, the circuit further includes: and a second operational amplifier 62, wherein the second operational amplifier 62 is connected between the signal output end and the third port of the adder 46, and the second operational amplifier 62 is configured to filter and amplify the target inverse signal to obtain an amplified target inverse signal.

Through the circuit, the target reverse signal can be amplified, so that the receiving sensitivity of the tag reader-writer is further improved.

Example 3

In this embodiment, a radio frequency identification signal processing apparatus is further provided, and the apparatus is used to implement the foregoing embodiments and preferred embodiments, and the description already made is omitted for brevity. As used below, the term "module" may be a combination of software and/or hardware that implements a predetermined function. Although the means described in the embodiments below are preferably implemented in software, an implementation in hardware, or a combination of software and hardware is also possible and contemplated.

Fig. 7 is a block diagram of a radio frequency identification signal processing apparatus according to an embodiment of the present invention, as shown in fig. 7, the apparatus including:

a receiving module 72, configured to receive a tag reverse signal sent by the radio frequency identification tag;

an obtaining module 74, coupled to the obtaining module 72, configured to obtain a signal parameter of a dc component included in the tag reverse signal;

and the eliminating module 76 is coupled to the obtaining module 74, and is configured to eliminate a dc component included in the tag reverse signal according to the signal parameter, so as to obtain a target reverse signal.

Alternatively, the rfid signal processing apparatus may be applied to, but not limited to, a radio frequency tag identification scenario. For example: and the label reader-writer identifies the radio frequency label according to the reverse signal fed back by the radio frequency label.

Alternatively, the rfid signal processing apparatus may be applied to, but not limited to, a tag reader, for example: UHF label reader-writer, label protocol analyzer, etc.

Receiving a tag reverse signal sent by a radio frequency identification tag through the device; acquiring signal parameters of direct current components included in the reverse signals of the tags; according to the technical scheme, the direct current component in the tag reverse signal is eliminated by obtaining the signal parameter of the direct current component in the received tag reverse signal, the target reverse signal is obtained, and the direct current component in the target reverse signal is reduced, so that the receiving sensitivity of the tag reader-writer is improved, and the problem of low receiving sensitivity of the tag reader-writer in the related technology is solved.

Optionally, the obtaining module 74 is configured to: sampling the reverse signal of the label through analog-to-digital conversion to obtain a sampling signal; the phase and amplitude of the DC component are extracted from the sampled signal.

Optionally, the cancellation module 76 is configured to: generating a feedback signal having a phase opposite to that of the DC component and having the same amplitude; and adding the generated feedback signal and the tag reverse signal, and eliminating a direct current component included in the tag reverse signal to obtain a target reverse signal.

Optionally, the receiving module 72 is configured to: receiving a signal sent by a radio frequency identification tag, wherein the signal sent by the radio frequency identification tag carries a tag reverse signal; a tag reverse signal is extracted from a signal transmitted from a radio frequency identification tag.

Optionally, the receiving module 72 is configured to: receiving an original signal sent by a radio frequency identification tag; and amplifying the received original signal to a preset range, and taking the amplified signal as a signal sent by the radio frequency identification tag.

Optionally, the apparatus further comprises: and an amplifying module, coupled to the eliminating module 76, for filtering and amplifying the target reverse signal to obtain an amplified target reverse signal.

It should be noted that, the above modules may be implemented by software or hardware, and for the latter, the following may be implemented, but not limited to: the modules are all positioned in the same processor; alternatively, the modules are respectively located in a plurality of processors.

Example 4

In this embodiment, a tag reader is further provided, and the tag reader includes: a radio frequency identification signal processing circuit, wherein the circuit comprises: the first port of the switching element is connected to the first port of the sampling circuit and the first port of the adder, the second port of the sampling circuit is connected to the second port of the adder, the second port of the switching element is connected to the signal input end, and the third port of the adder is connected to the signal output end;

the switching element is used for receiving a label reverse signal sent by the radio frequency identification label; the sampling circuit is used for acquiring signal parameters of direct current components included in the reverse signals of the labels; the adder is used for eliminating the direct current component included in the label reverse signal according to the signal parameter to obtain a target reverse signal.

Alternatively, the tag reader may be applied to, but not limited to, a radio frequency tag identification scenario. For example: and the label reader-writer identifies the radio frequency label according to the reverse signal fed back by the radio frequency label.

Optionally, the tag reader/writer includes: UHF.

By the tag reader-writer, the direct current component in the tag reverse signal is eliminated by acquiring the signal parameter of the direct current component in the received tag reverse signal to obtain the target reverse signal, and the direct current component in the target reverse signal is reduced, so that the receiving sensitivity of the tag reader-writer is improved, and the problem of low receiving sensitivity of the tag reader-writer in the related technology is solved.

Optionally, the sampling circuit is configured to: sampling the reverse signal of the label through analog-to-digital conversion to obtain a sampling signal; extracting the phase and amplitude of the direct current component according to the sampling signal; a feedback signal is generated that is in phase opposition and of the same magnitude as the dc component.

Optionally, the adder is configured to: and adding the generated feedback signal and the tag reverse signal, and eliminating a direct current component included in the tag reverse signal to obtain a target reverse signal.

Optionally, the switching element is for: receiving a signal sent by a radio frequency identification tag, wherein the signal sent by the radio frequency identification tag carries a tag reverse signal; a tag reverse signal is extracted from a signal transmitted from a radio frequency identification tag.

Through the tag reader-writer, the tag reverse signal can be extracted from the signal sent by the radio frequency identification tag, so that the forward signal possibly included in the tag reverse signal is filtered, the influence of the forward signal on the reverse signal is further eliminated, and the receiving sensitivity of the tag reader-writer is improved.

Optionally, the rfid signal processing circuit further includes: and the first operational amplifier is connected between the signal input end and the second port of the switching element, and is used for amplifying the tag reverse signal to a preset range and taking the amplified signal as the tag reverse signal.

Through the tag reader-writer, the original signal can be amplified, and then the direct current component in the amplified signal is eliminated. Therefore, by adopting the scheme, the receiving sensitivity of the tag reader-writer can be further improved.

Optionally, the rfid signal processing circuit further includes: and the second operational amplifier is connected between the signal output end and the third port of the adder, and is used for filtering and amplifying the target reverse signal to obtain an amplified target reverse signal.

By the tag reader-writer, a target reverse signal can be amplified, so that the receiving sensitivity of the tag reader-writer is further improved.

Reference will now be made in detail to the alternative embodiments of the present invention.

An optional embodiment of the present invention provides a radio frequency identification signal processing method, which performs real-time tracking and calculation on a demodulated forward direct current signal, locally generates a direct current signal with an opposite phase and the same amplitude, adds the direct current signal to the demodulated signal, removes the direct current signal, makes a signal entering an AD sampler only have a small signal (i.e., a target reverse signal) returned by a tag, and amplifies the tag signal before AD sampling, thereby improving the sensitivity of a card reader.

Fig. 8 is a block diagram of a UHF RFID receiving circuit according to an alternative embodiment of the present invention, and as shown in fig. 8, the UHF RFID receiving circuit includes three units: (1) an amplification filter unit (2) and a quadrature demodulation unit (3) drive unit. When the antenna receives the reverse signal and passes through the amplifying and filtering unit, the low noise amplifier compensates gain and suppresses channel noise, and the filter filters out-of-band spurious signals. Then the signal enters an orthogonal demodulation unit, a useful signal is demodulated by a demodulator and a local oscillation driving signal, and a high-frequency signal is filtered by a filter. And finally, amplifying and outputting the I/Q signal through a driving unit. The invention processes the signal at the driving unit (3) to offset the influence caused by carrier leakage, thereby improving the sensitivity.

Firstly, analyzing signals output by (2) the orthogonal demodulation unit, wherein several situations may occur by adopting a time sequence waveform of an I-path signal or a Q-path signal after orthogonal demodulation, fig. 9 is a schematic diagram of the time sequence waveform of the demodulated signal according to an alternative embodiment of the invention, as shown in fig. 9, time T1-T2 is a forward signal of a demodulation waveform emitted by an RFID, and time T2-T3 is a reverse signal of a demodulation waveform label; u1 is the forward signal peak. It can be seen from fig. 9 that the reverse signal may be either a positive or a negative value. The amplitude and phase of the forward signal and the reverse signal of the demodulation signal have no relation. In order to ensure that the waveform is not distorted, the intermediate frequency signal can be acquired in a direct current coupling mode, otherwise, the waveform distortion can affect the reverse signal.

In order to eliminate the influence of the forward signal on the reverse signal, an alternative embodiment of the present invention provides an rfid signal processing circuit, and fig. 10 is a block diagram of the rfid signal processing circuit according to the alternative embodiment of the present invention, and as shown in fig. 10, the circuit includes a first operational amplifier 102, a digital switch 104, a sampling circuit 106 (including ADC/DAC, etc.), an adder 108, and a second operational amplifier 110. The intermediate frequency signal processing is implemented in four steps, fig. 11 is a schematic diagram of an rfid signal processing circuit according to an alternative embodiment of the present invention, as shown in fig. 11, an original signal is a waveform 1102, and first, the amplitude of the signal is adjusted to a range of 0-3V, such as a waveform 1104, by the first operational amplifier 102. The digital switch 104 (e.g., a baseband time slot pulse switch) controls the forward signal to turn off and the reverse signal to turn on, as in waveform 1106. The signal passes through the sampling circuit 106, ADC sampling is performed on the signal of the waveform 1106, the dc component of the signal is analyzed, the DAC output is fed back to the adder 108 according to the algorithm, and the addition and subtraction processing is performed on the signal and the original signal, so that the dc of the signal is reduced to about 0V, as in the waveform 1108. The signal of the waveform 1108 is subjected to intermediate frequency filtering amplification to obtain a waveform 1110.

The circuit architecture in the optional embodiment of the invention is based on the size of the demodulated direct current signal, and the feedback is compensated by the DAC, so that the direct current bias caused by the leakage of the forward signal is offset, and the sensitivity is improved.

The circuit in the system of the optional embodiment of the invention adopts direct current coupling to realize no distortion of the waveform of the received and demodulated signal, adopts an analog switch technology, closes the forward signal in a time-sharing way, reduces the possibility of distortion caused by overlarge amplification factor of the amplifier, automatically monitors the direct current component of the IQ signal in real time, realizes real-time control feedback, can automatically and quickly compensate direct current bias by utilizing an MCU algorithm, and is easier for amplification processing of a reverse signal.

In summary, the rfid signal processing method, circuit, apparatus, and tag reader provided by the embodiments and optional embodiments of the present invention are provided.

The complexity of the radio frequency identification signal processing circuit is reduced, the cost of a hardware circuit is reduced, the circuit control response speed is high, the control is more accurate, the accuracy of the circuit control is improved, the waveform is free of distortion by adopting direct current coupling, the receiving sensitivity of a tag reader-writer is improved by a large improvement range, and the sensitivity can be improved to-90 dBm by experiment verification and is improved by about 35dB compared with that before the circuit is added.

The above embodiments are only intended to illustrate the technical solution of the present invention and not to limit the same, and a person skilled in the art can modify the technical solution of the present invention or substitute the same without departing from the spirit and scope of the present invention, and the scope of the present invention should be determined by the claims.

Example 5

Through the above description of the embodiments, those skilled in the art can clearly understand that the method according to the above embodiments can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware, but the former is a better implementation mode in many cases. Based on such understanding, the technical solutions of the present invention may be embodied in the form of a software product, which is stored in a storage medium (e.g., ROM/RAM, magnetic disk, optical disk) and includes instructions for enabling a terminal device (e.g., a mobile phone, a computer, a server, or a network device) to execute the method according to the embodiments of the present invention.

The embodiment of the invention also provides a storage medium. Alternatively, in the present embodiment, the storage medium may be configured to store program codes for performing the following steps:

s1, receiving a label reverse signal sent by the radio frequency identification label;

s2, acquiring signal parameters of direct current components included in the label reverse signals;

and S3, eliminating the direct current component included in the label reverse signal according to the signal parameters to obtain a target reverse signal.

Optionally, in this embodiment, the storage medium may include, but is not limited to: a U-disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a removable hard disk, a magnetic or optical disk, and other various media capable of storing program codes.

Optionally, in this embodiment, the processor executes the method steps described in the above embodiments according to the program code stored in the storage medium.

Optionally, the specific examples in this embodiment may refer to the examples described in the above embodiments and optional implementation manners, and this embodiment is not described herein again.

It will be apparent to those skilled in the art that the modules or steps of the present invention described above may be implemented by a general purpose computing device, they may be centralized on a single computing device or distributed across a network of multiple computing devices, and alternatively, they may be implemented by program code executable by a computing device, such that they may be stored in a storage device and executed by a computing device, and in some cases, the steps shown or described may be performed in an order different than that described herein, or they may be separately fabricated into individual integrated circuit modules, or multiple ones of them may be fabricated into a single integrated circuit module. Thus, the present invention is not limited to any specific combination of hardware and software.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method of processing radio frequency identification signals, comprising:

receiving a tag reverse signal sent by a radio frequency identification tag, wherein a radio frequency signal receiving circuit comprises an amplifying and filtering unit, an orthogonal demodulation unit and a driving unit, and the tag reverse signal is a tag reverse signal included in a signal output by the orthogonal demodulation unit;

acquiring signal parameters of a direct current component included in the tag reverse signal;

eliminating the direct current component included in the tag reverse signal according to the signal parameter to obtain a target reverse signal;

wherein obtaining the signal parameter of the direct current component included in the tag reverse signal comprises: sampling the reverse signals of the labels through analog-to-digital conversion to obtain sampling signals; extracting the phase and amplitude of the direct current component according to the sampling signal;

the receiving the tag reverse signal transmitted by the radio frequency identification tag comprises: receiving a signal sent by the radio frequency identification tag, wherein the signal sent by the radio frequency identification tag carries the tag reverse signal; and controlling the forward signal to be closed and the label reverse signal to be opened so as to extract the label reverse signal from the signal transmitted by the radio frequency identification label.

2. The method of claim 1, wherein removing the dc component included in the tag reverse signal according to the signal parameter to obtain the target reverse signal comprises:

generating a feedback signal having the same amplitude and opposite phase to the DC component;

and adding the generated feedback signal and the tag reverse signal, and eliminating the direct current component included in the tag reverse signal to obtain the target reverse signal.

3. The method of claim 1, wherein receiving the signal transmitted by the radio frequency identification tag comprises:

receiving an original signal sent by the radio frequency identification tag;

and amplifying the received original signal to a preset range, and taking the amplified signal as the signal sent by the radio frequency identification tag.

4. The method according to any one of claims 1 to 3, wherein after eliminating the DC component included in the tag reverse signal according to the signal parameter to obtain the target reverse signal, the method further comprises:

and filtering and amplifying the target reverse signal to obtain an amplified target reverse signal.

5. A radio frequency identification signal processing circuit, comprising: a switching element, a sampling circuit, and an adder, wherein,

a first port of the switching element is connected to a first port of the sampling circuit and a first port of the adder, a second port of the sampling circuit is connected to a second port of the adder, a second port of the switching element is connected to a signal input terminal, and a third port of the adder is connected to a signal output terminal;

the switch element is used for receiving a label reverse signal sent by the radio frequency identification label; the sampling circuit is used for acquiring signal parameters of direct current components included in the tag reverse signals; the adder is used for eliminating the direct current component included in the tag reverse signal according to the signal parameter to obtain a target reverse signal, wherein the radio frequency signal receiving circuit comprises an amplifying and filtering unit, an orthogonal demodulation unit and a driving unit, and the tag reverse signal is a tag reverse signal included in a signal output by the orthogonal demodulation unit;

wherein the sampling circuit is to: sampling the reverse signals of the labels through analog-to-digital conversion to obtain sampling signals; extracting the phase and amplitude of the direct current component according to the sampling signal; generating a feedback signal having the same amplitude and opposite phase to the DC component;

the switching element is configured to: receiving a signal sent by the radio frequency identification tag, wherein the signal sent by the radio frequency identification tag carries the tag reverse signal; and a controller for controlling the turning off of the forward signal and the turning on of the tag reverse signal to extract the tag reverse signal from the signal transmitted from the radio frequency identification tag.

6. The circuit of claim 5, wherein the adder is configured to:

7. The circuit of claim 5, further comprising: the first operational amplifier is connected between the signal input end and the second port of the switch element, and is used for amplifying the tag reverse signal to a preset range and taking the amplified signal as the tag reverse signal.

8. The circuit of claim 5, further comprising: and the second operational amplifier is connected between the signal output end and the third port of the adder, and is used for filtering and amplifying the target reverse signal to obtain an amplified target reverse signal.

9. A radio frequency identification signal processing apparatus, comprising:

the radio frequency signal receiving circuit comprises an amplifying and filtering unit, an orthogonal demodulation unit and a driving unit, wherein the tag reverse signal is a tag reverse signal contained in a signal output by the orthogonal demodulation unit;

the acquisition module is used for acquiring signal parameters of direct current components included in the tag reverse signals;

the eliminating module is used for eliminating the direct current component included in the label reverse signal according to the signal parameter to obtain a target reverse signal;

wherein the acquisition module is configured to: sampling the reverse signal of the label through analog-to-digital conversion to obtain a sampling signal; extracting the phase and amplitude of the direct current component according to the sampling signal;

the receiving module is further configured to: receiving a signal sent by a radio frequency identification tag, wherein the signal sent by the radio frequency identification tag carries a tag reverse signal; and controlling the forward signal to be closed and the label reverse signal to be opened so as to extract the label reverse signal from the signal transmitted by the radio frequency identification label.

10. A tag reader/writer, characterized by comprising: the radio frequency identification signal processing circuit of any of claims 5 to 8.