CN106919877A - A kind of super high frequency radio frequency recognition read-write machine and method - Google Patents

Abstract

The invention provides an ultra-high frequency radio frequency identification reader and method, including: a control module; a transmitting module; a directional coupling module; a radio frequency matching module; an antenna module; a vector modulation carrier cancellation module; a receiving module; an interface module; a power supply module . On the one hand, the isolation of the coupling module is increased by matching to reduce the carrier signal power leaked into the receiving chain by the transmitting module; on the other hand, the carrier signal power leaked into the receiving chain is reduced through vector modulation carrier cancellation technology. The invention uses radio frequency matching technology to change the impedance characteristics of the coupler, increases the isolation, and reduces the carrier signal power leaked from the transmitting module to the receiving link; uses vector modulation carrier cancellation technology to reduce the carrier signal leaking to the receiving link Power: Through the combination of the two technologies, the carrier power leaked into the receiving link is eliminated or reduced to a small enough level, and the signal returned by the tag is retained, thereby improving the sensitivity of the reader and increasing the reading and writing distance.

Description

An ultra-high frequency radio frequency identification reader and method

technical field

The invention relates to the field of radio frequency technology, in particular to an ultra-high frequency radio frequency identification reader-writer and method.

Background technique

Radio Frequency Identification (RFID) is a wireless communication technology, which is a non-contact automatic identification technology that uses radio frequency signal spatial coupling to identify targets and obtain target data. The most important advantage of RFID technology is non-contact identification, and it can read labels through harsh environments such as snow, fog, ice, paint, dust and other barcodes that cannot be used, and can also identify multiple labels at the same time. It has the advantages of diversification, strong anti-pollution ability, reusability, large memory capacity of data and encryption. With the development of RFID technology, its application fields are becoming more and more extensive, such as food safety traceability, book borrowing and returning system, access control system, warehouse management, parking lot management system, traffic monitoring management and many other fields. Some experts once pointed out that RFID technology may become another new technology that affects the global economy and life after mobile communication technology and Internet technology.

RFID electronic tags are divided into three types according to the way of obtaining energy sources: active, passive, semi-active and semi-passive. Active electronic tags are also called active tags. The working power of the tag is completely supplied by the internal battery, and the radio frequency energy required for the communication between the electronic tag and the reader is also provided by the battery; the tag has a long read/write distance and a large size. Thick, heavy, high cost, limited application fields, and the battery cannot be used for a long time, and the battery needs to be replaced after the energy is exhausted. Semi-active electronic tags are also called semi-active tags. The battery only supplies power to the circuit in the tag to maintain data; before the tag enters the working state, it is always in a dormant state, which is equivalent to a passive tag; when the tag enters the reader's readout When in the area, it is excited by the radio frequency signal sent by the reader and enters the working state; the advantages and disadvantages of the tag are basically the same as those of the active tag. Passive electronic tags, also known as passive tags, do not have a built-in battery, and the tags convert part of the energy from the radio frequency energy emitted by the reader to the power required for their work; the tags are small, light, thin, easy to install, and low in cost. It has a long service life, is suitable for various use occasions, and can be maintenance-free. In addition, UHF RFID (the international standard ISO18000-6C stipulates a working frequency band of 860-960MHz) has a shorter working wavelength than the high frequency 13.56MHz and its low frequency 125KHz, and the antenna is small and flexible in size and flexible in application. Source tags and readers have become the focus of the development of the Internet of Things in recent years.

Since the passive RFID tag is powered by the radio frequency signal emitted by the reader and sends out the information stored in the chip, this requires that the radio frequency transmission link is always in working condition, the isolation of the coupling circuit and the standing wave of the antenna are affected by the actual device. The impact causes part of the carrier signal power to leak into the receiving link, and the frequency of the signal returned by tag scattering is very close to the frequency of the carrier signal. Excessive carrier leakage will cause receiver saturation, affect the noise and sensitivity of the receiving link, and then affect the reader The effect and distance of reading and writing tags. At present, the UHF radio frequency identification reader 1 is built by adopting the scheme of separating components in the market, as shown in FIG. And the power supply module 17; the transmitting module 12 will leak a part of the carrier power into the receiving link due to the insufficient isolation of the coupling module 13. In addition, the antenna module 14 is not standard 50 ohms and will reflect a part of the carrier signal power due to the influence of the actual device In the receiving link, the receiving module 15 will be saturated and enter the nonlinear region due to the superposition of these two aspects, and even damage the device, affecting the noise and sensitivity of the receiving link. It is mainly used in some low-power short-distance fields.

Therefore, developing a high-performance UHF reader to reduce or eliminate the carrier signal power leaked into the receiving link and ensure the normal operation of the receiving link has become one of the urgent problems to be solved by those skilled in the art.

Contents of the invention

In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide a UHF radio frequency identification reader and method, which is used to solve the problem that the excessive power of the carrier signal leaked into the receiving link in the prior art affects the reception. Link noise and sensitivity issues.

In order to achieve the above purpose and other related purposes, the present invention provides a UHF radio frequency identification reader, the UHF radio frequency identification reader at least includes:

Control module, transmitting module, directional coupling module, radio frequency matching module, antenna module, vector modulation carrier cancellation module, receiving module, interface module and power supply module;

The control module is used to process the signals sent and received, and generate a control signal for controlling the vector modulation carrier cancellation module;

The transmitting module is connected with the control module, and is used to generate and send a radio frequency modulation signal written into the tag;

The directional coupling module is connected with the transmitting module, the radio frequency matching module and the vector modulation carrier cancellation module, and is used to conduct the radio frequency modulation signal written into the tag to the radio frequency matching module, or return the tag to the The signal is coupled to the vector modulation carrier cancellation module;

The radio frequency matching module is connected to the directional coupling module for adjusting the isolation of the directional coupling module;

The antenna module is connected to the radio frequency matching module, and is used to conduct the radio frequency modulation signal written into the tag to the tag in the form of electromagnetic waves in free space and receive the signal returned from the tag;

The vector modulation carrier cancellation module is connected with the directional coupling module, the control module and the receiving module, and is used to reduce the power of the carrier signal leaked into the receiving link, and transfer the signal returned by the tag to the receiving module;

The receiving module is connected between the vector modulation carrier cancellation module and the control module, receives the output signal of the vector modulation carrier cancellation module, mixes it to an intermediate frequency, and transmits it to the control module after amplification;

The interface module is used for data transmission;

The power module is used to supply power to the UHF radio frequency identification reader.

Preferably, the radio frequency matching module includes a set of L-shaped matching networks.

Preferably, the vector modulation carrier cancellation module is connected to the I ² C interface of the control module, so as to obtain the control signal.

Preferably, the vector modulation carrier cancellation module includes:

a first detector, a radio frequency vector modulator and a combiner;

The first detector is connected to the directional coupling module for detecting the power value of the carrier signal leaked into the receiving link, and sending the detection result to the control module to generate the control signal;

The radio frequency vector modulator is connected to the control module and the directional coupling module, and generates a radio frequency signal with equal amplitude and opposite phase to the carrier signal leaked into the receiving link according to the control signal;

The combiner is connected to the radio frequency vector modulator and the directional coupling module, and combines the radio frequency signal with the carrier signal leaked into the receiving link to reduce the carrier signal power in the receiving link, and Holds the signal returned by the label.

More preferably, the radio frequency vector modulator includes a four-channel digital-to-analog conversion circuit and a vector modulation circuit; the four-channel digital-to-analog conversion circuit receives the control signal and converts it into two sets of analog differential signals; the vector modulation circuit It is connected with the four-channel digital-to-analog conversion circuit and the directional coupling module, and simultaneously controls the amplitude and phase of the output signal according to the two sets of differential signals output by the four-channel digital-to-analog conversion circuit to generate the radio frequency signal.

More preferably, the vector modulation carrier cancellation module further includes a low noise amplifier connected to the combiner for amplifying the signal returned by the tag.

More preferably, the vector modulation carrier cancellation module further includes a second detector connected to the low noise amplifier for detecting the power of the radio frequency signal output by the low noise amplifier, and outputting the detection result to the control module to adjust the control signal.

Preferably, the transmitting module includes: a voltage-controlled oscillator connected to the control module and a power amplifier connected to the voltage-controlled oscillator.

More preferably, the receiving module includes: a mixer connected to the vector modulation carrier cancellation module and the voltage controlled oscillator, an intermediate frequency filter connected to the mixer, and an intermediate frequency filter connected to the intermediate frequency filter IF amplifier connected to the amplifier.

In order to achieve the above purpose and other related purposes, the present invention provides a UHF radio frequency identification reading and writing method, the UHF radio frequency identification reading and writing method at least includes:

Sending state: generate the radio frequency modulation signal written into the tag, and transmit the radio frequency modulation signal written into the tag to the tag in the form of electromagnetic waves in free space;

Receiving state: The antenna module receives the signal returned from the tag. On the one hand, it adjusts the impedance characteristics of the coupling module to improve the isolation and reduce the carrier signal power leaked from the transmitting module to the receiving link. On the other hand, it uses vector modulation carrier cancellation technology Reduce the power of the carrier signal leaked into the receive chain, and preserve the signal returned by the tag.

Preferably, the insertion loss and isolation of the coupling module are used as the basis for adjustment.

Preferably, specific methods for reducing the carrier signal power leaked into the receiving chain include:

Detecting the power value of the carrier signal leaked into the receiving link, and generating a control signal according to the detected value;

According to the control signal and generating a radio frequency signal equal in amplitude and opposite in phase to the carrier signal leaked into the receiving link;

The radio frequency signal is combined with the carrier signal leaked into the receiving chain, so as to reduce the power of the carrier signal leaked into the receiving chain and preserve the signal returned by the tag.

More preferably, the specific method for generating the radio frequency signal includes:

The control signal is converted into two sets of differential signals I and Q, and the power value of the carrier signal in the receiving link is collected, and the amplitude and phase of the output signal are simultaneously controlled by the two sets of differential signals I and Q to generate the radio frequency signal .

More preferably, the control precision of the amplitude reaches 0.5 dBm, and the control precision of the phase reaches 2°.

More preferably, the interval of the control signal is quickly found through a dichotomy method, so as to quickly determine the optimum range of the amplitude and phase of the radio frequency signal.

Preferably, it also includes detecting the received radio frequency signal power value after reducing the carrier signal leaked into the receiving chain, and if the detected value is less than the set value, it is considered that the carrier signal leaked into the receiving chain has been eliminated to be sufficiently small It does not affect the normal operation of the receiving link; if the detected value is greater than the set value, the control signal is adjusted to further reduce the carrier signal power leaked into the receiving link.

As mentioned above, the UHF radio frequency identification reader and method of the present invention have the following beneficial effects:

1. In the UHF radio frequency identification reader and method of the present invention, a radio frequency matching module is added between the directional coupling module and the antenna module, and the impedance characteristic of the coupler is changed by radio frequency matching technology, the isolation degree is increased, and the leakage from the transmitting module is reduced. to the carrier signal power in the receive chain, and has little effect on the main channel power.

2. In the UHF radio frequency identification reader and method of the present invention, a vector modulation carrier cancellation module is added between the directional coupling module and the receiving module, and the vector modulation carrier cancellation technology is used to reduce the carrier signal power leaked into the receiving link .

3. The UHF radio frequency identification reader and method of the present invention combine radio frequency matching technology and vector modulation carrier cancellation technology to eliminate or reduce the carrier power leaked into the receiving link to a small enough level, thereby improving reading and writing The receiving sensitivity of the reader plays a role in increasing the distance of the reader.

Description of drawings

FIG. 1 is a schematic diagram of a UHF radio frequency identification reader in the prior art.

FIG. 2 is a schematic diagram of the UHF RFID reader-writer of the present invention.

FIG. 3 is a schematic diagram of an embodiment of the UHF RFID reader-writer of the present invention. Component designation description

1 UHF radio frequency identification reader

11 control module

12 Transmitter module

13 coupling module

14 Antenna Module

15 receiving module

16 interface modules

17 power module

2 UHF radio frequency identification reader

21 control module

211~212 First~second analog-to-digital converters

22 Transmitter module

221 Voltage Controlled Oscillator

222 power amplifier

23 Directional coupling module

24 RF matching modules

25 antenna modules

251 single pole multiple throw switch

252 antennas

26 vector modulation carrier cancellation module

261 First detector

262 RF Vector Modulator

2621 Four-channel digital-to-analog conversion circuit

2622 filter circuit

2623 vector modulation circuit

263 Combiner

264 LNA

265 Second detector

27 receiving module

271 Mixer

272 IF filter

273 IF Amplifier

28 interface modules

29 power module

detailed description

Embodiments of the present invention are described below through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various modifications or changes can be made to the details in this specification based on different viewpoints and applications without departing from the spirit of the present invention.

Please refer to Figure 2 to Figure 3. It should be noted that the diagrams provided in this embodiment are only schematically illustrating the basic idea of the present invention, and only the components related to the present invention are shown in the diagrams rather than the number, shape and shape of the components in actual implementation. Dimensional drawing, the type, quantity and proportion of each component can be changed arbitrarily during actual implementation, and the component layout type may also be more complicated.

As shown in Figures 2 to 3, the present invention provides a UHF RFID reader-writer 2, the UHF RFID reader-writer 2 at least includes:

Control module 21 , transmitting module 22 , directional coupling module 23 , radio frequency matching module 24 , antenna module 25 , vector modulation carrier cancellation module 26 , receiving module 27 , interface module 28 and power supply module 29 .

As shown in FIG. 2 , the control module 21 is used to process the transmitted and received signals, and generate a control signal for controlling the vector modulation carrier cancellation module 26 .

Specifically, as shown in FIG. 3 , the control module 21 is connected to the transmitting module 22, the receiving module 27 and the vector modulation carrier cancellation module 26, and is used to output the write tag to the transmitting module 22. ASK modulation control signal; receive the digital signal returned by the tag from the receiving module 27 and store and identify; output the control signal of the vector modulation carrier cancellation module 26 after receiving the detection signal from the vector modulation carrier cancellation module 26 . The control module 21 further includes a first analog-to-digital converter 211 and a second analog-to-digital converter 212 for converting the analog detection signal into a digital signal.

As shown in FIG. 2 , the transmitting module 22 is connected with the control module 21 for generating and sending a radio frequency modulation signal written into the tag.

Specifically, as shown in FIG. 3 , the transmitting module 22 includes: a voltage-controlled oscillator 221 and a power amplifier 222 . The voltage-controlled oscillator 221 is connected to the control module 21, and converts the digital control signal output by the control module 21 into a radio frequency signal and outputs it to the power amplifier 222 for power amplification.

As shown in Figure 2, the directional coupling module 23 is connected with the transmitting module 22, the radio frequency matching module 24 and the vector modulation carrier cancellation module 26, and is used to conduct the radio frequency modulation signal written into the tag to the The radio frequency matching module 24, or the signal returned by the tag is coupled to the vector modulation carrier cancellation module 26.

Specifically, as shown in FIG. 3 , the directional coupling module 23 is a four-port device, which isolates the carrier signal sent by the UHF RFID reader-writer from the receiving link to a certain extent.

As shown in FIG. 2 , the radio frequency matching module 24 is connected to the directional coupling module 23 for adjusting the isolation of the directional coupling module 23 .

Specifically, as shown in FIG. 3 , the radio frequency matching module 24 is connected to the output end of the directional coupling module 23, including a group of L-shaped matching networks (not shown in the figure), according to the impedance of the directional coupling module 23 The characteristic adjusts the isolation of the directional coupling module 23, reduces the carrier signal power leaked from the transmitting module 22 into the receiving chain, and has almost no influence on the power of the main channel.

As shown in FIG. 2 , the antenna module 25 is connected to the radio frequency matching module 24 for transmitting the radio frequency modulation signal written into the tag to the tag in the form of electromagnetic waves and receiving the signal returned from the tag.

Specifically, as shown in Figure 3, the antenna module 25 includes a single-pole multi-throw switch 251 and an antenna 252, and the path connected to the antenna 252 is changed by switching the single-pole multi-throw switch 251, thereby realizing a multi-channel antenna Toggle to cover different orientations. The antenna 252 converts the guided wave propagating on the transmission line and the electromagnetic wave signal in free space to realize wireless communication.

As shown in Figure 2, the vector modulation carrier cancellation module 26 is connected with the directional coupling module 23, the control module 21 and the receiving module 27 for reducing the carrier signal power leaked into the receiving link, And transmit the signal returned by the tag to the receiving module 27. In this embodiment, the vector modulation carrier cancellation module 26 is connected to the I ² C interface of the control module 21 .

Specifically, as shown in FIG. 3 , the vector modulation carrier cancellation module 26 includes: a first detector 261 , a radio frequency vector modulator 262 , a combiner 263 , a low noise amplifier 264 and a second detector 265 .

The first detector 261 is connected to the directional coupling module 23, and detects the signals transmitted from the antenna module 25 and the directional coupling module 23, and the signals in the receiving link include useful signals returned by tags, signals from the The transmitting module 22 leaks the carrier signal in the receiving link and the carrier signal reflected back from the antenna module 25 in the receiving link. The latter two signals will interfere with the useful signal returned by the tag and increase the noise in the receiving link. , reducing receiver sensitivity. The first detector 261 detects the power value of the carrier signal leaked into the receiving link, and sends the detection result to the control module 21 through the first analog-to-digital converter 211, thereby generating the control Signal.

The radio frequency vector modulator 262 is connected with the control module 21 and the directional coupling module 23, and generates a radio frequency signal with equal amplitude and opposite phase with the carrier signal leaked into the receiving link according to the control signal.

More specifically, as shown in FIG. 3 , the radio frequency vector modulator 262 includes a four-channel digital-to-analog conversion circuit 2621 , a filter circuit 2622 and a vector modulation circuit 2623 . The four-channel digital-to-analog conversion circuit 2621 receives the control signal and converts it into two sets of analog differential signals. In this embodiment, the two sets of analog differential signals are I and Q differential signals, which are used for amplitude modulation and modulation respectively. Mutually. The filter circuit 2622 is connected to the four-channel digital-to-analog conversion circuit 2621 for filtering out clutter. The vector modulation circuit 2623 is connected to the filter circuit 2622 and the directional coupling module 23, and simultaneously controls the amplitude and phase of the output signal of the vector modulation circuit 2623 with two sets of I and Q differential signals, and generates and leaks to the receiving chain A radio frequency signal with equal amplitude and opposite phase to the carrier signal in the circuit.

The combiner 263 is connected to the radio frequency vector modulator 262 and the directional coupling module 23, and combines the radio frequency signal with the carrier signal leaked into the receiving link to reduce the carrier signal in the receiving link. power, and preserve the signal returned by the tag.

The low noise amplifier 264 is connected with the combiner 263 to amplify the signal returned by the tag.

The second detector 265 is connected to the low noise amplifier 264, and is used to detect the radio frequency signal power output by the low noise amplifier 264, and output the detection result to the control unit through the second analog-to-digital converter 212. Module 21 to adjust the control signal.

As shown in Figure 2, the receiving module 27 is connected between the vector modulation carrier cancellation module 26 and the control module 21, receives the output signal of the vector modulation carrier cancellation module 26, and transmits it to the Control module 21.

Specifically, as shown in FIG. 3 , the receiving module 27 includes: a mixer 271 , an intermediate frequency filter 272 and an intermediate frequency amplifier 273 . The mixer 271 is connected to the vector modulation carrier cancellation module 26 and the voltage controlled oscillator 221, and converts the radio frequency signal output by the vector modulation carrier cancellation module 26 into an intermediate frequency signal. The intermediate frequency filter 272 is connected to the mixer 271 for filtering. The IF amplifier 273 is connected to the IF filter 272 for amplifying the mixed IF signal.

As shown in Figures 2 to 3, the UHF radio frequency identification reader also includes an interface module 28 and a power module 29, the interface module 28 is used for data transmission, and the power module 29 is used The high-frequency radio frequency identification reader-writer 2 supplies power.

As shown in Figures 2 to 3, the present invention also provides a UHF radio frequency identification reading and writing method. In this embodiment, the UHF radio frequency identification reader is used to implement, and the UHF radio frequency identification Write methods include at least:

Sending state: generate the radio frequency modulation signal written into the tag, and transmit the radio frequency modulation signal written into the tag to the tag in the form of electromagnetic waves in free space.

Specifically, as shown in FIGS. 2 to 3 , the control module 21 outputs the signal written in the tag in the form of a digital signal, and loads the signal on the carrier signal through the transmitting module 22 to output in the form of a radio frequency signal. Directional coupling module 23 transmits to described radio frequency matching module 24, because the isolation degree of described directional coupling module 23 is limited, the carrier signal output in described transmitting module 22 will have a part to leak in the receiving chain, and described radio frequency matching module 24 Adjust the isolation of the directional coupling module 23 according to the impedance characteristics of the directional coupling module 23, reduce the carrier signal power leaked from the transmitting module 22 to the receiving link, and the signal written into the tag passes through the antenna The module 25 is converted into electromagnetic waves in free space for wireless transmission. Since the antenna module 25 is not matched to the standard 50 ohms due to the influence of actual devices and processing accuracy, it will reflect a part of the carrier signal to the receiving link.

Receiving state: The antenna module receives the signal returned from the tag. On the one hand, it adjusts the impedance characteristics of the coupling module to improve isolation and reduce the carrier signal power leaked from the transmitting module to the receiving link. On the other hand, it uses vector modulation carrier cancellation technology Reduce the power of the carrier signal leaked into the receive chain, and preserve the signal returned by the tag.

Specifically, as shown in FIGS. 2 to 3 , the signal returned by the tag is received through the antenna module 25. At this time, the receiving link includes the signal returned by the tag and the signal leaked from the transmitting module 22 into the receiving link. The carrier signal and the carrier signal reflected from the antenna module 25 back into the receiving link, the first detector 261 detects the power value of the carrier signal leaked into the receiving link, and passes the detection result through the first The analog-to-digital converter 211 sends to the control module 21 to generate the control signal.

The four-channel digital-to-analog conversion circuit 2621 receives the control signal and converts it into two sets of I and Q differential signals, and filters out clutter through the filter circuit 2622 . The vector modulation circuit 2623 receives the filtered I, Q two sets of differential signals, simultaneously controls the amplitude and phase of the output signal of the vector modulation circuit 2623 with the I, Q two sets of differential signals, and generates and leaks into the receiving chain A radio frequency signal with equal amplitude and opposite phase to the carrier signal. In this embodiment, the control module 21 uses a dichotomy method to quickly find the interval of the control signal, so as to quickly determine the optimum range of the amplitude and phase of the modulation signal, and greatly increase the operating speed.

The combiner 263 combines the radio frequency signal with the signal in the receiving chain (including the signal returned by the tag and the carrier signal leaked into the receiving chain), so as to cancel the carrier signal leaked into the receiving chain Power, keep the signal returned by the tag, and then use the low noise amplifier 264 to amplify the signal returned by the tag and output it to the receiving module 27.

The second detector 265 detects the radio frequency signal power value after the cancellation, and if the detected value is less than the set value, it is considered that the carrier signal leaked into the receiving link has been eliminated to be small enough to not affect the normal receiving link work; if the detected value is greater than the set value, the control signal is adjusted to further reduce the power of the carrier signal leaked into the receiving link. Since there is a conversion relationship between power and voltage, in this embodiment, the detected voltage value output by the low-noise amplifier 264 is used as the basis for judgment. When the detected voltage value is less than 0.7V, it is considered that the carrier signal power leaked into the receiving link It is small enough that it will not cause the devices in the receiving chain to enter the saturation region, will not damage the devices, and will not affect the noise and sensitivity of the receiving chain; when the voltage value is greater than 0.7V, it is considered that the leakage into the receiving chain The power of the carrier signal is still very high, which will still affect the noise and sensitivity of the receiving chain. Therefore, the control signal needs to be adjusted to further reduce the power of the carrier signal leaked into the receiving chain. The set value or the numerical value of the voltage is specifically set according to specific parameters such as signals and devices of the UHF RFID reader-writer, and is not limited to this embodiment.

As mentioned above, the UHF radio frequency identification reader and method of the present invention have the following beneficial effects:

1. In the UHF radio frequency identification reader and method of the present invention, a radio frequency matching module is added between the directional coupling module and the antenna module, and the impedance characteristic of the coupler is changed by radio frequency matching technology, the isolation degree is increased, and the leakage from the transmitting module is reduced. to the carrier signal power in the receive chain, and has little effect on the main channel power.

2. In the UHF radio frequency identification reader and method of the present invention, a vector modulation carrier cancellation module is added between the directional coupling module and the receiving module, and the vector modulation carrier cancellation technology is used to reduce the carrier signal power leaked into the receiving link .

3. The UHF radio frequency identification reader and method of the present invention combine radio frequency matching technology and vector modulation carrier cancellation technology to eliminate or reduce the carrier power leaked into the receiving link to a small enough level, thereby improving reading and writing The receiving sensitivity of the reader plays a role in increasing the distance of the reader.

In summary, the present invention provides a UHF radio frequency identification reader and method, including: a control module; a transmitting module for sending and writing tag signals; a directional coupling module; a radio frequency matching module for adjusting the impedance characteristics of the directional coupling module; The antenna module; the vector modulation carrier cancellation module used to reduce the power of the carrier signal leaked into the receiving link; the receiving module receiving the return signal of the tag. Sending state: generate the RF modulation signal written into the tag, and conduct the RF modulation signal written into the tag to the next stage, adjust the impedance characteristics of the coupling module, improve the isolation, and reduce the carrier signal power leaked into the receiving link. Then the signal is transmitted to the tag in the form of electromagnetic waves in free space; receiving state: the antenna module receives the signal returned from the tag, on the one hand, by adjusting the impedance characteristics of the coupling module, the isolation is improved and the leakage of the transmitting module into the receiving link is reduced On the other hand, the carrier signal power leaked into the receiving link is reduced by vector modulation carrier cancellation technology, and the signal returned by the tag is retained. In the ultra-high frequency radio frequency identification reader and method of the present invention, a radio frequency matching module is added between the directional coupling module and the antenna module, and the impedance characteristic of the coupler is changed by radio frequency matching technology, the isolation degree is increased, and the leakage from the transmitting module to the receiving module is reduced. The power of the carrier signal in the link has little effect on the power of the main channel; add a vector modulation carrier cancellation module between the directional coupling module and the receiving module, and use the vector modulation carrier cancellation technology to reduce the carrier leakage into the receiving link Signal power: Combining radio frequency matching technology and vector modulation carrier cancellation technology, the carrier power leaked into the receiving chain is eliminated or reduced to a small enough size. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has high industrial application value.

The above-mentioned embodiments only illustrate the principles and effects of the present invention, but are not intended to limit the present invention. Anyone skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical ideas disclosed in the present invention should still be covered by the claims of the present invention.

Claims (16)

1. A kind of ultra-high frequency radio frequency identification reader-writer, it is characterized in that, described ultra-high frequency radio frequency identification reader-writer comprises at least: Control module, transmitting module, directional coupling module, radio frequency matching module, antenna module, vector modulation carrier cancellation module, receiving module, interface module and power supply module; The control module is used to process the signals sent and received, and generate a control signal for controlling the vector modulation carrier cancellation module; The transmitting module is connected with the control module, and is used to generate and send a radio frequency modulation signal written into the tag; The directional coupling module is connected with the transmitting module, the radio frequency matching module and the vector modulation carrier cancellation module, and is used to conduct the radio frequency modulation signal written into the tag to the radio frequency matching module, or return the tag to the The signal is coupled to the vector modulation carrier cancellation module; The radio frequency matching module is connected to the directional coupling module for adjusting the isolation of the directional coupling module; The antenna module is connected to the radio frequency matching module, and is used to conduct the radio frequency modulation signal written into the tag to the tag in the form of electromagnetic waves in free space and receive the signal returned from the tag; The vector modulation carrier cancellation module is connected with the directional coupling module, the control module and the receiving module, and is used to reduce the power of the carrier signal leaked into the receiving link, and transfer the signal returned by the tag to the receiving module; The receiving module is connected between the vector modulation carrier cancellation module and the control module, receives the output signal of the vector modulation carrier cancellation module, mixes it to an intermediate frequency, and transmits it to the control module after amplification; The interface module is used for data transmission; The power module is used to supply power to the UHF radio frequency identification reader. 2. The UHF radio frequency identification reader according to claim 1, wherein the radio frequency matching module comprises a group of L-shaped matching networks. 3 . The UHF radio frequency identification reader according to claim 1 , wherein the vector modulation carrier cancellation module is connected to the I ² C interface of the control module, so as to obtain the control signal. 4 . 4. UHF radio frequency identification reader-writer according to claim 1, is characterized in that: described vector modulation carrier cancellation module comprises: a first detector, a radio frequency vector modulator and a combiner; The first detector is connected to the directional coupling module for detecting the power value of the carrier signal leaked into the receiving link, and sending the detection result to the control module to generate the control signal; The radio frequency vector modulator is connected to the control module and the directional coupling module, and generates a radio frequency signal with equal amplitude and opposite phase to the carrier signal leaked into the receiving link according to the control signal; The combiner is connected to the radio frequency vector modulator and the directional coupling module, and combines the radio frequency signal with the carrier signal leaked into the receiving link to reduce the carrier signal power in the receiving link, and Holds the signal returned by the label. 5. UHF radio frequency identification reader-writer according to claim 4, is characterized in that: said radio frequency vector modulator comprises four-channel digital-to-analog conversion circuit and vector modulation circuit; Said four-channel digital-to-analog conversion circuit receives said The control signal is converted into two sets of analog differential signals; the vector modulation circuit is connected to the four-channel digital-to-analog conversion circuit and the directional coupling module, and according to the two sets of differential signals output by the four-channel digital-to-analog conversion circuit Simultaneously control the amplitude and phase of the output signal to generate the radio frequency signal. 6. The UHF RFID reader-writer according to claim 4, characterized in that: the vector modulation carrier cancellation module also includes a low-noise amplifier connected with the combiner for amplifying the return signal of the tag Signal. 7. The UHF RFID reader-writer according to claim 6, characterized in that: the vector modulation carrier cancellation module also includes a second detector, connected with the low noise amplifier, for detecting the The low noise amplifier outputs the power of the radio frequency signal, and outputs the detection result to the control module, so as to adjust the control signal. 8. The UHF RFID reader-writer according to claim 1, characterized in that: the transmitting module includes: a voltage-controlled oscillator connected to the control module and a power supply connected to the voltage-controlled oscillator amplifier. 9. The UHF RFID reader-writer according to claim 8, characterized in that: the receiving module comprises: a mixer connected to the vector modulation carrier cancellation module and the voltage-controlled oscillator, An intermediate frequency filter connected to the mixer, and an intermediate frequency amplifier connected to the intermediate frequency filter. 10. A method for reading and writing UHF radio frequency identification, characterized in that, the method for reading and writing UHF radio frequency identification comprises: Sending state: generate the radio frequency modulation signal written into the tag, and transmit the radio frequency modulation signal written into the tag to the tag in the form of electromagnetic waves in free space; Receiving state: The antenna module receives the signal returned from the tag. On the one hand, it adjusts the impedance characteristics of the coupling module to improve the isolation and reduce the carrier signal power leaked from the transmitting module to the receiving link. On the other hand, it uses vector modulation carrier cancellation technology Reduce the power of the carrier signal leaked into the receive chain, and preserve the signal returned by the tag. 11. The UHF radio frequency identification reading and writing method according to claim 10, characterized in that: the insertion loss and isolation of the coupling module are used as the basis for adjustment. 12. The UHF radio frequency identification reading and writing method according to claim 10, characterized in that: the specific method for reducing the carrier signal power leaked into the receiving link comprises: Detecting the power value of the carrier signal leaked into the receiving link, and generating a control signal according to the detected value; Generate a radio frequency signal with equal amplitude and opposite phase to the carrier signal leaked into the receiving link according to the control signal; The radio frequency signal is combined with the carrier signal leaked into the receiving link to reduce the power of the carrier signal leaked into the receiving link and retain the signal returned by the tag. 13. The UHF radio frequency identification reading and writing method according to claim 12, characterized in that: the specific method for generating the radio frequency signal comprises: The control signal is converted into two sets of differential signals I and Q, and the power value of the carrier signal in the receiving link is collected, and the amplitude and phase of the output signal are simultaneously controlled by the two sets of differential signals I and Q to generate the radio frequency signal . 14. The UHF radio frequency identification reading and writing method according to claim 13, characterized in that: the amplitude control accuracy reaches 0.5dBm, and the phase control accuracy reaches 2°. 15. The radio frequency identification reading and writing method according to claim 13, characterized in that: quickly find the interval of the control signal by dichotomy, so as to quickly determine the optimal range of the amplitude and phase of the radio frequency signal. 16. The UHF radio frequency identification reading and writing method according to claim 10, characterized in that: after reducing the carrier signal leaked into the receiving link, detecting the received radio frequency signal power value, if the detected value is less than The set value considers that the carrier signal leaked into the receiving link has been eliminated to be small enough to not affect the normal operation of the receiving link; if the detected value is greater than the set value, the control signal is adjusted to further reduce the leakage into the receiving link The carrier signal power in .