CN102185817B - Method and device for transmitting information from reader-writer to label - Google Patents

Abstract

The embodiment of the present invention provides a method and device for transmitting information from a reader to a tag. The method includes: transmitting a certain length of continuous high-level radio frequency carrier; if receiving the identification code sent by the tag, generating a frame synchronization sequence, sending the frame synchronization sequence to the tag, wherein the frame synchronization sequence includes: a delimiter indicating the starting point of the frame synchronization sequence, two calibration symbols for calibrating the reference frequency and data information; if the receiving identifier returned by the tag is received, a baseband command is generated according to the instruction of the background control system, and the baseband command is encoded, which will contain the frame synchronization sequence and the coded baseband command The carrier signal is sent to the tag; if the synchronization establishment identifier returned by the tag is received, it is determined that the synchronization communication establishment with the tag is completed. The invention can realize the self-calibration of the reference frequency, thereby reducing the power consumption of the chip.

Description

A method and device for transmitting information from a reader-writer to a tag

technical field

The invention relates to the communication field, in particular to a method and device for transmitting information from a reader to a tag.

Background technique

The radio frequency identification (RFID, Radio Frequency Identification) technology in the field of communication is an automatic identification technology that uses radio frequency for long-distance communication to identify items. This technology is compatible with today's digital mobile business, and can realize automatic identification and remote real-time monitoring and management. It is one of the popular technologies in contemporary information technology. When working, the RFID tag is installed on the item that needs to be authenticated, and the tag sends the identity information about the item to the receiving device through electromagnetic waves. The RFID system can track and manage almost all physical objects in this way. RFID has broad application prospects in many fields such as industrial automation, commercial automation, transportation control management, and anti-counterfeiting technology.

A general radio frequency identification system consists of three parts, namely RFID tags, readers and background data management systems. For the sake of simplicity, the RFID tag is simply referred to as a tag hereinafter. The reader sends a radio frequency signal of a certain frequency through the antenna. When the tag enters the working area of the antenna, the tag receives the radio frequency signal to obtain energy and is activated. Communication is established between the tag and the reader, and the tag stores the information stored by itself. After the reader demodulates and decodes the received signal, it transmits the tag information data to the background data management system through the interface, and can also execute the commands sent by the data management system to perform different functions.

Synchronization is a very important technical issue in the RFID communication process. The reader and the tag need to work in unison, which requires a synchronization system to ensure. Synchronization needs to be realized through a frame synchronization code. The frame synchronization code itself does not contain the data information of the label, but the data information can only be transmitted after the synchronization between the transceiver devices is established through the frame synchronization code. Therefore, establishing synchronization is to carry out information Necessity and prerequisite for transmission. The quality of synchronization performance will directly affect the performance of communication. If there is a synchronization error or loss of synchronization, it will cause communication performance degradation or communication interruption. Therefore, in order to achieve stable and fast communication in the RFID communication system, it is necessary to ensure the synchronization between receiving and sending.

The inventor found in the process of implementing the present invention that currently in the ISO18000-6C protocol, the data rate of the return link is determined by counting the number of samples of TRcal(). In this way, the size of the reference frequency determines the accuracy of the data rate of the return link. The larger the reference frequency, the higher the accuracy of the data rate of the return link, but a large reference frequency will lead to large power consumption. . A temperature compensation circuit can be added in the analog circuit to improve the stability of the reference frequency, but this increases the complexity of chip design and power consumption of the chip. In addition, the ISO18000-6C standard only defines a delimiter with a time length of 12.5us. After each power-on, the tag will write the calibration value into the on-chip RAM after receiving the delimiter, using PR-ASK or other For similar non-rectangular pulses, the tag sampling cannot ensure that the delimiter in the frame synchronization code is restored to a time length of 12.5us, making the reference frequency error, which will cause a high bit error rate in the communication process.

Contents of the invention

Embodiments of the present invention provide a method and device for transmitting information from a reader-writer to a tag, so as to solve the synchronization problem from the reader-writer to the tag.

The above object of the embodiments of the present invention is achieved through the following technical solutions:

A method for transmitting information from a reader-writer to a tag, the method is applied to a reader-writer of an RFID system, and the method includes: transmitting a certain length of continuous high-level radio frequency carrier; if receiving the identification code sent by the tag, Then generate a frame synchronization sequence, and send the frame synchronization sequence to the tag, wherein the frame synchronization sequence includes: a delimiter representing the starting point of the frame synchronization sequence, two Calibrator and data information; if the receiving identifier returned by the tag is received, a baseband command is generated according to the instructions of the background control system, and the baseband command is encoded, which will include the frame synchronization sequence and the encoded The carrier signal of the subsequent baseband command is sent to the tag; if the synchronization establishment identifier returned by the tag is received, it is determined that the synchronization communication establishment with the tag is completed.

A method for transmitting information from a reader-writer to a tag, the method is applied to a tag of an RFID system, and the method includes: when receiving a continuous high-level radio frequency carrier sent by the reader-writer, sending a message to the reader-writer Identification code; receive and store the frame synchronization sequence returned by the reader, wherein the frame synchronization sequence includes: a delimiter representing the starting point of the frame synchronization sequence, two used to calibrate the reference frequency Calibrator and data information; obtain a reference frequency calibration value according to the frame synchronization sequence, perform self-calibration on the reference frequency in the tag according to the reference frequency calibration value; send a receiving identifier to the reader, and receive the The carrier signal that contains the frame synchronization sequence and the coded baseband command returned by the reader-writer; if the frame synchronization sequence in the carrier signal is the same as the saved frame synchronization sequence, then send a synchronization establishment identifier to the reader ; Decode the encoded baseband command and execute the baseband command.

A reader, the reader includes: a transmitting unit for transmitting a certain length of continuous high-level radio frequency carrier; a first generating unit for generating a frame after receiving the identification code sent by the tag Synchronization sequence, the frame synchronization sequence includes: a delimiter indicating the starting point of the frame synchronization sequence, two calibration symbols and data information for calibrating the reference frequency; the first sending unit is used to send the first The frame synchronization sequence generated by a generation unit is sent to the tag; the second generation unit is used to generate a baseband command according to the instruction of the background control system after receiving the receiving identifier returned by the tag; the encoding unit is used to The baseband command generated by the second generation unit is encoded; the second sending unit is configured to send the carrier signal including the frame synchronization sequence generated by the first generation unit and the baseband command encoded by the encoding unit to the The tag; a determining unit, configured to determine that the establishment of the synchronization communication with the tag is completed when receiving the synchronization establishment identifier returned by the tag.

A tag, the tag includes: a first sending unit, configured to send an identification code to the reader-writer when receiving a continuous high-level radio frequency carrier sent by the reader-writer; a first receiving unit, configured to Receive the frame synchronization sequence returned by the reader-writer after the first sending unit sends the identification code to the reader-writer, wherein the frame synchronization sequence includes: a delimitation indicating the starting point of the frame synchronization sequence symbol, two calibration symbols and data information for calibrating the reference frequency; a storage unit for storing the frame synchronization sequence received by the first receiving unit; a calibration unit for receiving the frame synchronization sequence according to the first receiving unit Obtain a reference frequency calibration value from the received frame synchronization sequence, and perform self-calibration on the reference frequency in the tag according to the reference frequency calibration value; the second sending unit is used to send to the read-write device after the calibration unit self-calibrates The reader sends the receiving identifier; the second receiving unit is used to receive the baseband that contains the frame synchronization sequence and the coded baseband returned by the reader after the second sending unit sends the receiving identifier to the reader The carrier signal of the command; the comparison unit is used to compare the frame synchronization sequence in the carrier signal received by the second receiving unit with the frame synchronization sequence stored in the storage unit; the third sending unit is used to The comparison result of the comparison unit is that when the frame synchronization sequence in the carrier signal received by the second receiving unit is the same as the frame synchronization sequence stored in the storage unit, send a synchronization establishment flag to the reader symbol; a decoding unit, configured to decode the encoded baseband command received by the second receiving unit and execute the baseband command.

An RFID system, the system includes a reader-writer and a tag, and the reader-writer is used to: transmit a certain length of continuous high-level radio frequency carrier; when receiving the identification code sent by the tag, generate a frame synchronization sequence, sending the frame synchronization sequence to the tag, wherein the frame synchronization sequence includes: a delimiter indicating the starting point of the frame synchronization sequence, two calibration symbols for calibrating the reference frequency and data Information; when receiving the receiving identifier returned by the tag, generate a baseband command according to the instruction of the background control system, and encode the baseband command, and include the frame synchronization sequence and the coded baseband command The carrier signal is sent to the tag; when the synchronization establishment identifier returned by the tag is received, it is determined that the synchronization communication with the tag is established; the tag is used to: receive the continuous high power sent by the reader When the radio frequency carrier is flat, send the identification code to the reader; receive and save the frame synchronization sequence returned by the reader, wherein the frame synchronization sequence includes: a delimitation representing the starting point of the frame synchronization sequence symbol, two calibration symbols and data information for calibrating the reference frequency; obtain a reference frequency calibration value according to the frame synchronization sequence, and perform self-calibration on the reference frequency in the tag according to the reference frequency calibration value; The reader sends and receives the identifier, and receives the carrier signal containing the frame synchronization sequence and the encoded baseband command returned by the reader; when the frame synchronization sequence in the carrier signal is the same as the saved frame synchronization sequence , sending a synchronization establishment identifier to the reader; decoding the encoded baseband command and executing the baseband command.

Using the method and device provided by the embodiment of the present invention in the link from the reader-writer of the RFID system to the tag, the reference frequency self-calibration can be realized through the frame synchronization sequence of the present invention, the tag does not need to add a temperature compensation circuit, and the tag chip is saved area, thereby reducing the power consumption of the chip, and can still ensure the stability of the reference frequency under different temperature and humidity conditions, thereby ensuring that the reader and the tag can work in unison, and also make the error in the communication process The code rate is very low.

Description of drawings

The drawings described here are used to provide further understanding of the present invention, constitute a part of the application, and do not limit the present invention. In the attached picture:

Fig. 1 is a schematic diagram of a communication system of a reader-writer and a tag for radio frequency identification;

Fig. 2 is the structural block diagram of using the reader-writer of the method provided by the present invention and label;

FIG. 3 is a flowchart of a method for transmitting information from a reader to a tag according to an embodiment of the present invention;

Fig. 4 is a schematic diagram of a frame synchronization sequence in this embodiment;

FIG. 5 is a schematic diagram of the improved Manchester encoding method provided in this embodiment;

Fig. 6 is the simulation experiment graph of the communication mode adopting three different frame synchronization sequences;

FIG. 7 is a flowchart of another method for transmitting information from a reader to a tag according to an embodiment of the present invention;

FIG. 8 is a functional block diagram of a reader/writer provided by an embodiment of the present invention;

FIG. 9 is a block diagram of a label provided by an embodiment of the present invention;

Fig. 10 is a composition block diagram of an RFID system provided by an embodiment of the present invention.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention more clear, the embodiments of the present invention will be further described in detail below in conjunction with the embodiments and the accompanying drawings. Here, the exemplary embodiments and descriptions of the present invention are used to explain the present invention, but not to limit the present invention.

Figure 1 is a schematic diagram of the communication system of the reader and tag used for radio frequency identification, please refer to Figure 1, the reader 11 transmits an ACK modulation signal, when one or more tags 12 enter the working range of the reader The radio frequency signal transmitted by the reader/writer 11 can be received, and the required data information can be returned according to the received command; the reader/writer 11 transmits the data information to the computer data management system 13 after receiving it.

Fig. 2 is the structural block diagram of using the reader-writer of the method provided by the present invention and label, please refer to Fig. 2, reader-writer 21 comprises the antenna 211 that has receiving and transmitting function, the modem 212 that plays modulation and demodulation effect, is used for A codec 213 for encoding and decoding, a frame synchronization sequence generator 214 for generating a frame synchronization sequence, and a read-write controller 215 for generating baseband commands and other commands; similarly, the tag 22 also has an antenna 221, a modem 222 , codec 223, in addition, the tag also includes a voltage doubler rectifier circuit 224 for converting the radio frequency carrier into the voltage required for tag work, a memory 225 for storing various data information, and a memory for performing data read and write operations and a data controller 226 that generates various identification codes.

Fig. 3 is a flowchart of a method for transmitting information from a reader-writer to a tag provided by an embodiment of the present invention, the method is applied to a reader-writer of an RFID system, please refer to Fig. 3, the method includes:

Step 301: Transmit a certain length of continuous high-level radio frequency carrier;

Among them, the reader can transmit a certain length of continuous high-level radio frequency carrier through its antenna. The carrier does not contain any data information, and the length is at least 8 encoding cycles.

Step 302: If the identification code sent by the tag is received, generate a frame synchronization sequence, and send the frame synchronization sequence to the tag;

Wherein, the frame synchronization sequence includes: a delimiter indicating the starting point of the frame synchronization sequence, two calibration symbols used for calibrating the reference frequency and data information.

Among them, after the tag receives the radio frequency carrier, its internal voltage doubler rectification circuit converts the radio frequency carrier into the voltage required for the tag to work. At this time, the tag is activated and generates a binary random number of 0-15 bits. If the random If the number is 0, the tag will directly transmit the identification code representing the identity of the tag. If the random number is not 0, the tag will automatically decrement the random number by 1 until the random number becomes 0. The ID code is sent out. If the random numbers generated by two or more tags are 0 at the same time, a collision occurs at this time, that is, the reader receives two or more identification codes at the same time, and the reader sends a new random number command to the corresponding multiple tags without performing the next step.

Among them, after the reader/writer receives the identification code of the tag, the frame synchronization sequence generator generates a frame synchronization sequence and transmits it to the modem, modulates it onto the radio frequency carrier, and then sends it to the tag. Wherein the frame synchronization sequence includes the following three parts: a) a delimiter representing the starting point of the frame synchronization sequence, which is a low level with a time length of T, and the time length T is determined by the data rate of the reader Determine, usually between 8.25-25us; b) Two calibration characters used to calibrate the reference frequency, a high level and a low level represent a calibration character, and the time length of each calibration character is the same as the delimiter The time length of symbols is equal; c) data information, which includes binary data 0 represented by two code elements "10", binary data 1 represented by two code elements "11", two continuous high values of unit time length The binary violation data represented by the level and the binary data 1 represented by two symbols "01" are used to establish synchronous communication from the reader to the tag, where a high-level pulse of a unit time length represents the symbol " 1", a low-level pulse with a unit time length represents the symbol "0".

Fig. 4 is the frame synchronous sequence schematic diagram of present embodiment, can find out the structure of the frame synchronous sequence of present embodiment by the figure: a delimiter that is represented by the low level that time length is T; Two calibrators, with a A high level and a low level represent a calibration character, and the time length of each calibration character is equal to the time length of the delimiter; the binary data 0 represented by two code elements "10" is represented by two code elements " Binary data 1 represented by 11", a binary violation data represented by two consecutive high levels per unit time length, and binary data 1 represented by two symbols "01" are arranged and combined in sequence. , wherein a high-level pulse of a unit time length represents a symbol "1", and a low-level pulse of a unit time length represents a symbol "0". The frame synchronization sequence of this embodiment includes violations, which can reduce the probability of false synchronization during synchronous communication. Experiments have proved that the autocorrelation function of the data information has a sharp single-peak characteristic, and the autocorrelation is very high, which can reach more than 5.12dB. Moreover, the self-calibration of the reference frequency can be realized through the frame synchronization sequence of this embodiment, and the tag does not need to add a temperature compensation circuit, which saves the area of the tag chip, thereby reducing the power consumption of the chip, and making the bit error rate in the communication process very low .

Although there is one binary violation data in the frame synchronization sequence structure shown in FIG. The number is determined by different encoding methods.

In this embodiment, data may be encoded using any feasible encoding manner, such as Manchester encoding (Manchester), PIE encoding, Miller encoding, etc., which will not be repeated here. This embodiment provides an improved Manchester encoding method for specific description below.

Fig. 5 is a schematic diagram of the improved Manchester coding method provided by this embodiment, and its coding principle is: use a high-level pulse of a unit time length to represent the symbol "1", and use a unit time-length low-level pulse to represent the code element "0"; use two code elements "10" to represent the binary number 0 in the source data; when a single binary number 1 appears in the source data, use two code elements "11" to represent the binary number 1; When a continuous binary number 1 appears in the source data, two code elements "11" are used to represent the binary number 1 of the odd number, and two code elements "01" are used to represent the binary number 1 of the even number; that is, for continuous binary numbers Number 1, the binary number 1 of the first bit is represented by two code elements "11", the binary number 1 of the second bit is represented by two code elements "01", and the binary number 1 of the third bit is represented by two code elements The binary number 1 of the fourth bit is represented by two code elements "01", ..., and so on. In other words, a binary number 0 is represented by a high level pulse of a unit time length and a low level pulse of a unit time length, and an odd binary number 1 is represented by two high level pulses of a unit time length. A low-level pulse of a unit time length and a high-level pulse of a unit time length represent a binary number 1 of an even number of bits.

The binary numbers 0 and 1 encoded according to the above encoding method are shown in Figure 5, wherein Dperiod is the symbol period, HLW is a high-level pulse per unit time length, which represents the symbol "1", and LLW is the low level pulse per unit time length Level pulse, which represents the symbol "0". The symbol "01" means that the low level is before the high level; "10" means that the high level is before the low level, and the symbol "11" means two high levels.

When the improved Manchester encoding method provided by this embodiment is used to encode data, the number of violation data in the frame synchronization sequence of this embodiment can be one, and the use of this frame synchronization format can greatly reduce the gap between the reader and the tag. The probability of false synchronization between inter-communications, this is because the reader uses the improved Manchester encoding method to encode data, and there are at most three consecutive high levels of unit time length in the encoded baseband command, while in this embodiment There are four consecutive high levels in the frame synchronization sequence (see Figure 3). By judging the number of continuous high levels, the baseband command and the frame synchronization sequence can be distinguished, so that during communication, the probability that the baseband command and the frame synchronization sequence are exactly the same is greatly reduced, that is, the probability of false synchronization is greatly reduced. The method for judging false synchronization is also applicable to other encoding methods, and the number of binary violation data in the frame synchronization sequence structure of this embodiment is determined by different encoding methods.

Step 303: If the receiving identifier sent by the tag is received, generate a baseband command according to the instruction of the background control system, encode the baseband command, and include the frame synchronization sequence and the coded baseband command The carrier signal is sent to the tag;

Wherein, after receiving the frame synchronization sequence, the tag demodulates it to obtain a reference frequency calibration value, performs self-calibration on the reference frequency in the tag according to the reference frequency calibration value, and saves the frame synchronization sequence into the memory, and at the same time Return a reception identifier to the reader to indicate the completion of frame synchronization sequence reception. After the tag demodulates the frame synchronization sequence, the time length sum of the delimiter and the calibrator is averaged as the reference frequency calibration value, thereby preventing the occurrence of time deviation and ensuring that the calibration of the reference frequency is very accurate.

Among them, after the reader/writer receives the receiving identifier, its read-write controller generates baseband commands according to the instructions of the background control system, and its codec encodes the baseband commands, and then the modem converts the frames generated by the frame synchronization sequence generator into The synchronization sequence and the coded baseband command are modulated onto the radio frequency carrier and sent out through the antenna. Among them, the frame synchronization sequence is attached in front of the baseband command.

Step 304: If the synchronization establishment identifier returned by the tag is received, determine that the establishment of synchronization communication with the tag is completed.

Among them, the tag demodulates the received RF carrier signal containing the frame synchronization sequence and the coded baseband command, and compares the demodulated frame synchronization sequence with the frame synchronization sequence stored in the memory. If the two sequences are the same, Then the tag sends a synchronization establishment identifier indicating synchronization establishment to the reader, thereby establishing synchronous communication between the two, and at the same time, the label decodes the baseband command to obtain the required baseband command content, and executes the following according to the command One-step operation; otherwise, the tag sends a sync error identifier to the reader indicating a sync error.

Wherein, if the reader/writer receives the synchronization error identifier, it will regenerate a frame synchronization sequence and send it to the tag, so as to establish synchronous communication with the tag. The specific communication process is the same as steps 302-304, and will not be repeated here.

In this embodiment, the baseband commands transmitted by the reader and various other commands are all generated by the read-write controller of the reader, such as commands to regenerate random numbers; All kinds of marking codes (ie, various identifiers) are generated by the data controller of the tag, such as synchronously establishing identifiers.

Through the information transmission method from the reader-writer to the tag in this embodiment, the self-calibration of the reference frequency of the tag is realized, no need to increase the temperature compensation circuit, and the area of the tag chip is saved, thereby reducing the overall power consumption of the chip and ensuring Readers and tags work in unison.

In order to make the effect of the information transmission method from the reader to the tag of this embodiment more clear, the method of this embodiment will be described below in conjunction with an application example.

FIG. 6 is a curve diagram of a simulation experiment using three different communication modes of frame synchronization sequences, please refer to FIG. 6 .

Under the condition of a Gaussian white noise channel model, the frame synchronization performance simulation is performed on Manchester, PIE and the improved Manchester coding of the embodiment of the present invention, and the probability of false synchronization is analyzed. In the simulation, each data frame is composed of a frame synchronization sequence and information bits, wherein the format of the frame synchronization sequence contained in the data frame encoded by Manchester and PIE is a known format defined by its encoding method, and the improved Manchester of the embodiment of the present invention is adopted. The frame synchronization sequence format contained in the encoded data frame is the format shown in Figure 4, in which the information bits are composed of 32 randomly generated 0 and 1 sequences after corresponding encoding, and the average value is obtained after repeated analysis 1,000,000 times. During synchronous detection, a correlation operation is performed on the frame synchronous sequence, and if it is greater than the threshold value, the synchronous success is considered, otherwise false synchronous will occur.

The simulation results are shown in FIG. 6 , where MMC in the figure represents the improved Manchester encoding method of the embodiment of the present invention. It can be seen from FIG. 6 that the improved Manchester encoding adopts the frame synchronization sequence of the embodiment of the present invention, and its false synchronization probability is obviously the lowest in the entire SNR range.

Although the present invention describes the information transmission method of the present invention in the form of a specific embodiment, those skilled in the art know that other communication steps can also be used to realize the information transmission process from the reader to the tag. Any information transmission method including the frame synchronization sequence structure of the present invention will fall within the protection scope of the present invention.

Fig. 7 is a flow chart of a method for transmitting information from a reader to a tag provided by an embodiment of the present invention. The method is applied to a tag in an RFID system. Please refer to Fig. 7. The method includes:

Step 701: When receiving the continuous high-level radio frequency carrier sent by the reader-writer, send the identification code to the reader-writer;

Step 702: Receive and store the frame synchronization sequence returned by the reader, wherein the frame synchronization sequence includes: a delimiter representing the starting point of the frame synchronization sequence, two calibration symbols used to calibrate the reference frequency character and data information;

Step 703: Obtain a reference frequency calibration value according to the frame synchronization sequence, and self-calibrate the reference frequency in the tag according to the reference frequency calibration value;

Step 704: Send the receiving identifier to the reader, and receive the carrier signal including the frame synchronization sequence and the encoded baseband command returned by the reader;

Step 705: If the frame synchronization sequence in the carrier signal is the same as the stored frame synchronization sequence, send a synchronization establishment identifier to the reader;

Step 706: Decode the encoded baseband command and execute the baseband command.

The method of this embodiment corresponds to the information transmission method applied to the reader-writer to the tag in the embodiment shown in FIG. 3, because in the embodiment shown in FIG. The working process of the label in the interaction process has been described in detail, and will not be repeated here.

In the embodiment shown in Figure 3, the information transmission process from the reader to the tag is emphasized, and the transmission process from the tag to the reader is not described in detail, because any known transmission method and encoding method can be used to achieve For the information transmission from the tag to the reader, for example, when the tag sends information to the reader, in consideration of the processing capability of the tag itself, a simple Miller encoding method is usually used for information transmission.

Through the information transmission method from the reader-writer to the tag in this embodiment, the self-calibration of the reference frequency of the tag is realized, no need to increase the temperature compensation circuit, and the area of the tag chip is saved, thereby reducing the overall power consumption of the chip and ensuring Readers and tags work in unison.

Fig. 8 is a functional block diagram of a reader-writer provided by an embodiment of the present invention, please refer to Fig. 8, the reader-writer includes:

The transmitting unit 801 is used to transmit a certain length of continuous high-level radio frequency carrier;

The first generation unit 802 is used to generate a frame synchronization sequence after receiving the identification code sent by the tag, and the frame synchronization sequence includes: a delimiter representing the starting point of the frame synchronization sequence, two Calibrator and data information for calibration of the reference frequency;

The first sending unit 803 is configured to send the frame synchronization sequence generated by the first generating unit 802 to the tag;

The second generating unit 804 is configured to generate a baseband command according to an instruction of the background control system after receiving the receiving identifier returned by the tag;

an encoding unit 805, configured to encode the baseband command generated by the second generating unit 804;

The second sending unit 806 is configured to send the carrier signal including the frame synchronization sequence generated by the first generating unit 802 and the baseband command encoded by the encoding unit 805 to the tag;

The determining unit 807 is configured to, when receiving the synchronization establishment identifier returned by the tag, determine that the synchronization communication establishment with the tag is completed.

In one embodiment, the first generating unit 802 is further configured to: regenerate a frame synchronization sequence when receiving the synchronization error identifier returned by the tag, and the regenerated frame synchronization sequence includes: The delimiter of the starting point of the synchronization sequence, two calibration symbols and data information for calibrating the reference frequency; the first sending unit 803 is also used to: synchronize the frame regenerated by the first generating unit 802 The sequence is sent to the tag to establish synchronous communication with the tag.

In one embodiment, the delimiter included in the frame synchronization sequence generated by the first generation unit 802 is a low level for a certain time length, and the time length is determined by the data rate of the reader-writer; The calibration symbol contained in the frame synchronization sequence generated by the first generation unit 802 includes a high level and a low level, and the time length of each calibration symbol is equal to the time length of the delimiter; the first generation unit 802 generates The data information contained in the frame synchronization sequence includes binary data 0 represented by two symbols 10, binary data 1 represented by two symbols 11, binary violation data represented by two continuous high levels per unit time length, And the binary data 1 represented by two symbols 01, wherein a high-level pulse of a unit time length represents a symbol 1, and a low-level pulse of a unit time length represents a symbol 0.

In one embodiment, the continuous high-level radio frequency carrier of a certain length transmitted by the transmitting unit 801 does not contain data information, and the certain length is not greater than 8 coding cycles.

In one embodiment, the time length of the delimiter contained in the frame synchronization sequence generated by the first generating unit 802 is between 8.25-25us.

In this embodiment, the transmitting unit 801, the first sending unit 803, and the second sending unit 806 can be realized by an antenna and a modem of the reader-writer; the first generating unit 802 can be realized by a frame synchronization sequence generator; the second The generation unit 804 and the determination unit 807 can be implemented by a read-write controller; the encoding unit 805 can be implemented by a codec. Since the structural composition and functions of the reader/writer have been described in the above-mentioned FIG. 2 and FIG. 3 , they will not be repeated here.

Through the reader-writer of this embodiment, the self-calibration of the reference frequency of the tag is realized without adding a temperature compensation circuit, saving the area of the tag chip, thereby reducing the overall power consumption of the chip, and ensuring that the reader-writer and the tag can Coordinate work in tandem.

Figure 9 is a block diagram of a label provided by an embodiment of the present invention, please refer to Figure 9, the label includes:

The first sending unit 901 is configured to send the identification code to the reader when receiving the continuous high-level radio frequency carrier sent by the reader;

The first receiving unit 902 is configured to receive the frame synchronization sequence returned by the reader-writer after the first sending unit 901 sends the identification code to the reader-writer, wherein the frame synchronization sequence includes: a representation The delimiter of the starting point of the frame synchronization sequence, two calibration symbols and data information for calibrating the reference frequency;

a storage unit 903, configured to store the frame synchronization sequence received by the first receiving unit 902;

A calibration unit 904, configured to obtain a reference frequency calibration value according to the frame synchronization sequence received by the first receiving unit 902, and perform self-calibration on the reference frequency in the tag according to the reference frequency calibration value;

The second sending unit 905 is configured to send the receiving identifier to the reader after the calibration unit 904 self-calibrates;

The second receiving unit 906 is configured to receive the carrier signal containing the frame synchronization sequence and the coded baseband command returned by the reader-writer after the second sending unit 905 sends the receiving identifier to the reader-writer ;

a comparison unit 907, configured to compare the frame synchronization sequence in the carrier signal received by the second receiving unit 906 with the frame synchronization sequence stored in the storage unit 903;

The third sending unit 908 is configured to make the comparison result of the comparing unit 907 that the frame synchronization sequence in the carrier signal received by the second receiving unit 906 is the same as the frame synchronization sequence stored in the storage unit 903 At the same time, send a synchronization establishment identifier to the reader;

The decoding unit 909 is configured to decode the encoded baseband command received by the second receiving unit 906 and execute the baseband command.

In one embodiment, the third sending unit 908 is further configured to compare the result of the comparing unit 907 to the frame synchronization sequence in the carrier signal received by the second receiving unit 906 and the stored When the frame synchronization sequences saved by the unit 903 are different, send a synchronization error identifier to the reader.

In one embodiment, the reference frequency calibration value used by the calibration unit 904 is an average value of the sum of the time lengths of the delimiter and the calibrator in the frame synchronization sequence.

In this embodiment, the first sending unit 901, the first receiving unit 902, the second sending unit 905, the second receiving unit 906, and the third sending unit 908 can be realized by the antenna of the tag and a modem; the storage unit 903 can be realized by The storage unit of the tag; the calibration unit 904 and the comparison unit 907 can be realized by the data controller of the tag; the decoding unit 909 can be realized by the codec of the tag. Since the structural components and functions of the label have been described in the aforementioned FIG. 2 and FIG. 3 , details will not be repeated here.

Through the tag of this embodiment, the self-calibration of the reference frequency of the tag is realized, no need to increase the temperature compensation circuit, saving the area of the tag chip, thereby reducing the overall power consumption of the chip, and ensuring that the reader and the tag can be in step coordinate work.

Fig. 10 is a composition block diagram of an RFID system provided by an embodiment of the present invention, please refer to Fig. 10, the RFID system includes: a reader 1001 and a tag 1002, wherein:

The reader/writer 1001 is used to: transmit a certain length of continuous high-level radio frequency carrier; when receiving the identification code sent by the tag, generate a frame synchronization sequence, and send the frame synchronization sequence to the tag, wherein , the frame synchronization sequence includes: a delimiter indicating the starting point of the frame synchronization sequence, two calibration symbols and data information for calibrating the reference frequency; when receiving the receiving identifier returned by the tag, Generate a baseband command according to the instructions of the background control system, and encode the baseband command, and send the carrier signal containing the frame synchronization sequence and the encoded baseband command to the tag; return after receiving the tag When the synchronous establishment identifier of the tag is determined, it is determined that the establishment of synchronous communication with the tag is completed;

The tag 1002 is used to: when receiving the continuous high-level radio frequency carrier sent by the reader-writer, send the identification code to the reader-writer; receive and save the frame synchronization sequence returned by the reader-writer, wherein, the The frame synchronization sequence includes: a delimiter indicating the starting point of the frame synchronization sequence, two calibration symbols and data information for calibrating the reference frequency; the reference frequency calibration value is obtained according to the frame synchronization sequence, and according to the reference The frequency calibration value self-calibrates the reference frequency in the tag; sends the receiving identifier to the reader, and receives the carrier signal containing the frame synchronization sequence and the encoded baseband command returned by the reader; When the frame synchronization sequence in the carrier signal is the same as the stored frame synchronization sequence, send a synchronization establishment identifier to the reader; decode the encoded baseband command and execute the baseband command.

In this embodiment, the communication process between the reader-writer 1001 and the tag 1002 includes the following steps:

Step 1: The reader 1001 transmits a certain length of continuous high-level radio frequency carrier through the antenna, and the carrier does not contain any data information.

Step 2: After the tag 1002 receives the continuous high-level RF carrier wave sent by the reader-writer 1001 , it obtains energy from it to be activated, and sends an identification code to the reader-writer 1001 .

Step 3: After the reader 1001 receives the identification code of the tag 1002, it generates a frame synchronization sequence and modulates it onto the radio frequency carrier, and then sends it to the tag 1002; the structure of the frame synchronization sequence has been done in the above part A detailed introduction will not be repeated here.

Step 4: After receiving the frame synchronization sequence, the tag 1002 demodulates it to obtain a reference frequency calibration value, performs self-calibration on the reference frequency in the tag 1002 according to the value, and saves the frame synchronization sequence into the memory, and at the same time A reception identifier is returned to the reader/writer 1001.

Step 5: After receiving the identifier, the reader/writer 1001 generates and encodes the baseband command according to the instructions of the background control system, and modulates the frame synchronization sequence and the encoded baseband command generated by the frame synchronization sequence generator to the radio frequency carrier , sent out through the antenna, where the frame synchronization sequence is attached in front of the baseband command.

Step 6: The tag 1002 demodulates the received RF carrier signal containing the frame synchronization sequence and the baseband command, and compares the demodulated frame synchronization sequence with the frame synchronization sequence stored in the memory. If the two sequences are the same, the tag 1002 sends a synchronization establishment identifier to the reader 1001, thereby establishing synchronous communication between the two, and at the same time, the tag 1002 decodes the baseband command to obtain the required baseband command content, and executes the next step according to the command; Otherwise, the tag sends a synchronization error identifier to the reader 1001 .

Step 7: If the reader/writer 1001 receives a synchronization error identifier, re-execute the steps 3-6 until the synchronization communication is established.

The reader-writer 1001 of this embodiment can be realized by the reader-writer shown in Figure 8, and the tag 1002 of this embodiment can be realized by the tag shown in Figure 9, because in the embodiment shown in Figure 8 and Figure 9, the The reader and tag are described in detail, and will not be repeated here.

Through the RFID system of this embodiment, the self-calibration of the reference frequency of the tag is realized without adding a temperature compensation circuit, saving the area of the tag chip, thereby reducing the overall power consumption of the chip, and ensuring that the reader and the tag can keep pace Work in unison.

The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein may be directly implemented by hardware, software modules executed by a processor, or a combination of both. Software modules can be placed in random access memory (RAM), internal memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other Any other known storage medium.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the scope of the present invention. Protection scope, within the spirit and principles of the present invention, any modification, equivalent replacement, improvement, etc., shall be included in the protection scope of the present invention.

Claims (17)

1. a read write line is to the information transferring method of label, and described method is applied to the read write line of rfid system, it is characterized in that, described method comprises:

The continuous high level radio-frequency carrier of emission certain-length;

If receive the identity code that label sends, then produce a frame synchronization sequence, described frame synchronization sequence is sent to described label, wherein, described frame synchronization sequence comprises: the delimiter, two of the starting point of an expression frame synchronization sequence is used for calibration symbol and data message that reference frequency is calibrated;

If receive the reception identifier that described label returns, then the instruction according to the back bench control system produces the base band order, and described base band order encoded, the carrier signal that will comprise the base band order behind described frame synchronization sequence and the described coding sends to described label;

If what receive that described label returns sets up identifier synchronously, then determine to set up with the synchronous communication of described label and finish.

2. method according to claim 1 is characterized in that, after the base band order behind described frame synchronization sequence and the described coding was sent to described label, described method also comprised:

If receive the timing error identifier that described label returns, then produce a frame synchronization sequence again, and the described frame synchronization sequence that produces again sent to described label, in order to set up synchronous communication with described label, wherein, the described frame synchronization sequence that produces again comprises: the delimiter of the starting point of an expression frame synchronization sequence, two are used for calibration symbol and data message that reference frequency is calibrated.

3. method according to claim 1 and 2 is characterized in that:

Described delimiter is the low level of certain hour length, and described time span is determined by the data transfer rate size of described read write line;

Described calibration symbol comprises a high level and a low level, and the time span of each calibration symbol all equates with the time span of delimiter;

The binary data 1 that described data message comprises the binary data 0 represented with two code elements 10, represent with two code elements 11, the binary system fault data of representing with two continuous high level of unit interval length and the binary data of representing with two code elements 01 1, wherein, the high level pulse of a unit interval length represents that the low level pulse of 1, one unit interval length of code element represents code element 0.

4. method according to claim 1 is characterized in that, the continuous high level radio-frequency carrier of described certain-length does not comprise data message, and described certain-length is not more than 8 code period.

5. method according to claim 1 is characterized in that, the time span of described delimiter is between 8.25-25us.

6. a read write line is to the information transferring method of label, and described method is applied to the label of rfid system, it is characterized in that, described method comprises:

When the continuous high level radio-frequency carrier that receives that read write line sends, send identity code to described read write line;

Receive the frame synchronization sequence that described read write line returns and preserve, wherein, described frame synchronization sequence comprises: the delimiter of the starting point of an expression frame synchronization sequence, two are used for calibration symbol and data message that reference frequency is calibrated;

Obtain the reference frequency calibration value according to described frame synchronization sequence, according to described reference frequency calibration value the reference frequency in the described label is carried out self calibration;

Send to described read write line and to receive identifier, the carrier signal that comprises the base band order behind frame synchronization sequence and the coding that receives that described read write line returns;

If the frame synchronization sequence in the described carrier signal is identical with the frame synchronization sequence of preservation, then sends to described read write line and set up identifier synchronously;

To the base band command decode behind the described coding and carry out described base band order.

7. method according to claim 6 is characterized in that:

If described frame synchronization sequence is different with the frame synchronization sequence of preservation, then send the timing error identifier to described read write line.

8. method according to claim 6 is characterized in that, described reference frequency calibration value is delimiter and the mean value of calibrating the time span sum that accords with in the described frame synchronization sequence.

9. a read write line is characterized in that, described read write line comprises:

Transmitter unit is for the continuous high level radio-frequency carrier of emission certain-length;

First generation unit, be used for behind the identity code that receives the label transmission, produce a frame synchronization sequence, described frame synchronization sequence comprises: the delimiter, two of the starting point of an expression frame synchronization sequence is used for calibration symbol and data message that reference frequency is calibrated;

First transmitting element is used for the frame synchronization sequence that described first generation unit produces is sent to described label;

Second generation unit is used for after receiving the reception identifier that described label returns, and produces the base band order according to the instruction of back bench control system;

Coding unit is used for the base band order that described second generation unit produces is encoded;

Second transmitting element is used for comprising the frame synchronization sequence of described first generation unit generation and the carrier signal of the base band order behind the described coding unit coding sends to described label;

Determining unit, be used for receive that described label returns set up identifier synchronously the time, determine to set up with the synchronous communication of described label and finish.

10. read write line according to claim 9 is characterized in that:

Described first generation unit also is used for: when receiving the timing error identifier that described label returns, again produce a frame synchronization sequence, the described frame synchronization sequence that produces again comprises: the delimiter of the starting point of an expression frame synchronization sequence, two are used for calibration symbol and data message that reference frequency is calibrated;

Described first transmitting element also is used for: the frame synchronization sequence that described first generation unit is produced again sends to described label, in order to set up synchronous communication with described label.

11. read write line according to claim 9 is characterized in that, the delimiter that the frame synchronization sequence that described first generation unit produces comprises is the low level of certain hour length, and described time span is determined by the data transfer rate size of described read write line; The calibration symbol that the frame synchronization sequence that described first generation unit produces comprises comprises a high level and a low level, and the time span of each calibration symbol all equates with the time span of delimiter; The binary data 1 that the data message that the frame synchronization sequence that described first generation unit produces comprises comprises the binary data 0 represented with two code elements 10, represent with two code elements 11, the binary system fault data of representing with two continuous high level of unit interval length and the binary data of representing with two code elements 01 1, wherein, the high level pulse of a unit interval length represents that the low level pulse of 1, one unit interval length of code element represents code element 0.

12. read write line according to claim 9 is characterized in that, the continuous high level radio-frequency carrier of the certain-length of described transmitter unit emission does not comprise data message, and described certain-length is not more than 8 code period.

13. read write line according to claim 9 is characterized in that, the time span of the delimiter that the frame synchronization sequence that described first generation unit produces comprises is between 8.25-25us.

14. a label is characterized in that, described label comprises:

First transmitting element is used for sending identity code to described read write line when the continuous high level radio-frequency carrier that receives that read write line sends;

First receiving element, be used for after described read write line sends identity code, receiving the frame synchronization sequence that described read write line returns at described first transmitting element, wherein, described frame synchronization sequence comprises: the delimiter, two of the starting point of an expression frame synchronization sequence is used for calibration symbol and data message that reference frequency is calibrated;

Memory cell is used for the frame synchronization sequence that described first receiving element of storage receives;

Alignment unit, the frame synchronization sequence that is used for receiving according to described first receiving element obtains the reference frequency calibration value, according to described reference frequency calibration value the reference frequency in the described label is carried out self calibration;

Second transmitting element is used for sending the reception identifier to described read write line behind described alignment unit self calibration;

Second receiving element is used for receiving that described read write line returns comprises the carrier signal of the base band order behind frame synchronization sequence and the coding after described second transmitting element sends described reception identifier to described read write line;

Comparing unit, the frame synchronization sequence of preserving for frame synchronization sequence and the described memory cell of the described carrier signal that described second receiving element is received compares;

The 3rd transmitting element, for the comparative result at described comparing unit be, when the frame synchronization sequence that the frame synchronization sequence in the described carrier signal that described second receiving element receives and described memory cell are preserved is identical, sends to described read write line and to set up identifier synchronously;

Decoding unit, the base band command decode behind the coding that is used for described second receiving element is received is also carried out described base band order.

15. label according to claim 14 is characterized in that:

Described the 3rd transmitting element also is used at the comparative result of described comparing unit, the frame synchronization sequence that frame synchronization sequence in the described carrier signal that described second receiving element receives and described memory cell are preserved sends the timing error identifier to described read write line not simultaneously.

16. label according to claim 14 is characterized in that:

The reference frequency calibration value that described alignment unit utilizes is delimiter and the mean value of calibrating the time span sum that accords with in the described frame synchronization sequence.

17. a rfid system, described system comprises read write line and label, it is characterized in that:

Described read write line is used for: the continuous high level radio-frequency carrier of outwards launching certain-length; When receiving the identity code of label transmission, produce a frame synchronization sequence, described frame synchronization sequence is sent to described label, wherein, described frame synchronization sequence comprises: the delimiter, two of the starting point of an expression frame synchronization sequence is used for calibration symbol and data message that reference frequency is calibrated; When receiving the reception identifier that described label returns, instruction according to the back bench control system produces the base band order, and described base band order encoded, the carrier signal that will comprise the base band order behind described frame synchronization sequence and the described coding sends to described label; Receive that described label returns set up identifier synchronously the time, determine to set up with the synchronous communication of described label and finish;

Described label is used for: when the continuous high level radio-frequency carrier that receives that read write line sends, send identity code to described read write line; Receive the frame synchronization sequence that described read write line returns and preserve, wherein, described frame synchronization sequence comprises: the delimiter of the starting point of an expression frame synchronization sequence, two are used for calibration symbol and data message that reference frequency is calibrated; Obtain the reference frequency calibration value according to described frame synchronization sequence, according to described reference frequency calibration value the reference frequency in the described label is carried out self calibration; Send to described read write line and to receive identifier, the carrier signal that comprises the base band order behind frame synchronization sequence and the coding that receives that described read write line returns; When the frame synchronization sequence in described carrier signal is identical with the frame synchronization sequence of preservation, set up identifier synchronously to described read write line transmission; To the base band command decode behind the described coding and carry out described base band order.

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