CN111310506A - Decoding method and device for RFID reader - Google Patents

Abstract

Embodiments of the present invention provide a decoding method and device for an RFID reader, belonging to the technical field of digital signal processing, and solving the problem of a high bit error rate of an RFID reader in a low signal-to-noise ratio environment in the prior art. The method includes: receiving a return signal of an electronic tag; obtaining an in-phase signal and a quadrature signal from the return signal at a preset sampling frequency, where the preset sampling frequency is a preset multiple of the return frequency of the return signal; according to the in-phase signal According to the data phase of the quadrature signal, the complex signal corresponding to the return signal is obtained; according to the return frequency, the preset sampling frequency, the preset frequency deviation range and the encoding type of the return signal, the data to be decoded and the actual number of oversampling in the complex signal are determined ; According to the encoding type of the returned signal and the actual oversampling number, determine the decoding result corresponding to the data to be decoded in the correlation period corresponding to the actual oversampling number. The embodiments of the present invention are applicable to the decoding process of the RFID reader/writer.

Description

Decoding method and device for RFID reader

technical field

The invention relates to the technical field of digital signal processing, in particular to a decoding method and device for an RFID reader/writer.

Background technique

RFID (Radio Frequency Identification, radio frequency identification) technology is a wireless communication technology widely used in logistics, asset management, anti-counterfeiting and other aspects. One of the core technologies of RFID technology is decoding technology.

The RFID reader/writer performs decoding after receiving the input signal of the electronic tag. In the prior art, the input signal to be decoded is not clearly defined. The input signal includes in-phase signal and quadrature signal. In the process of changing the distance between the RFID reader and the electronic tag, the strong signal will rapidly change between the in-phase and quadrature signals. When the processing speed cannot keep up with the transformation speed of the strong signal, the demodulation will cause bit errors.

SUMMARY OF THE INVENTION

The purpose of the embodiments of the present invention is to provide a decoding method and device for an RFID reader, which solves the problem of a high bit error rate of the RFID reader in the prior art in a low signal-to-noise ratio environment, and overcomes the problem of RFID reading. The rapid change of strong signal caused by the relative movement of the writer and the electronic tag.

In order to achieve the above purpose, an embodiment of the present invention provides a decoding method for an RFID reader, the method includes: receiving a return signal of an electronic tag; obtaining an in-phase signal from the return signal at a preset sampling frequency and a quadrature signal, the preset sampling frequency is a preset multiple of the return frequency of the return signal; according to the data phase of the in-phase signal and the quadrature signal, the complex signal corresponding to the return signal is obtained; According to the return frequency, the preset sampling frequency, the frequency preset deviation range and the encoding type of the return signal, determine the data to be decoded in the complex signal and the actual oversampling number of a single pilot tone; The encoding type of the returned signal and the actual oversampling number are used to determine the decoding result corresponding to the data to be decoded in the correlation period corresponding to the actual oversampling number.

Further, the obtaining the in-phase signal and the quadrature signal from the return signal at the preset sampling frequency includes: sampling through an analog-to-digital converter ADC, and sampling the in-phase signal and the quadrature signal in the return signal by The analog domain is transformed into the digital domain; the in-phase signal and the quadrature signal in the digital domain are filtered respectively at the preset sampling frequency.

Further, obtaining the complex signal corresponding to the return signal according to the data phase of the in-phase signal and the quadrature signal includes: according to F=(I+j*Q)*e ^(-j*Φ) , obtain the complex signal F corresponding to the return signal, where I is the in-phase signal, Q is the quadrature signal, and Φ is the calculated value of the channel phase, where Φ≈atan(Q/I).

Further, after obtaining the complex signal corresponding to the return signal according to the data phase of the in-phase signal and the quadrature signal, the method further includes: comparing the real part of the complex signal with a preset compare the signal thresholds; when the real part of the complex signal is lower than the preset signal threshold, determine that the return signal of the electronic tag is an invalid signal, and end the decoding operation of the return signal; When the real part is not lower than the preset signal threshold, it is determined that the return signal of the electronic tag is a valid signal, and the decoding operation of the return signal is continued.

Further, according to the return frequency, the preset sampling frequency, the frequency preset deviation range and the encoding type of the return signal, determine the data to be decoded in the complex signal and the actual frequency of the single pilot tone. The number of samples includes: obtaining a single pilot tone in the complex signal according to H _l =F _S /[F ₀ *(1+r)], H _h =F _S /[F ₀ *(1-r)] The lower limit H _l and the upper limit H _h of the number of oversampling, where F ₀ is the return frequency, F _S is the preset sampling frequency, and ±r% is the frequency preset deviation range; according to The lower limit value and the upper limit value of the oversampling number, the value range of the oversampling number of the single pilot tone in the complex signal is obtained; according to the value range of the oversampling number and the return signal Encoding type, determine the preamble capture coefficient corresponding to each oversampling number in the value range of the oversampling number; use the preamble capture coefficient corresponding to each oversampling number as the preamble matching corresponding to each oversampling number The coefficient of the filter; the real part of the complex signal is matched with the preamble matched filter corresponding to each oversampling number to obtain the matching output value corresponding to each oversampling number; The oversampling number corresponding to the value is used as the actual oversampling number of the single pilot tone in the complex signal; according to the encoding protocol corresponding to the encoding type, determine the preamble corresponding to the actual oversampling number, and remove the The data after the preamble in the complex signal is used as the data to be decoded.

Further, determining the decoding result corresponding to the data to be decoded in the correlation period corresponding to the actual oversampling number according to the encoding type of the return signal and the actual oversampling number includes: according to the return signal The encoding type and the actual number of oversamplings are determined to determine the sample point values of the first waveform and the second waveform in the relevant period; in the data to be decoded, extract the waveform data in the relevant period; Multiply and accumulate the waveform data with the sample point value of the first type of waveform and the sample point value of the second type of waveform, respectively, to obtain the first type of correlation result corresponding to the first type of waveform and The second type of correlation result corresponding to the second type of waveform; the maximum value between the first type of correlation result and the second type of correlation result is taken as the signal decision result; the waveform corresponding to the signal decision result is determined is the decoding result corresponding to the data to be decoded in the correlation period.

Further, performing a multiplication and accumulation operation on the waveform data with the sample point value of the first type of waveform and the sample point value of the second type of waveform, respectively, to obtain the first waveform corresponding to the first type of waveform. A correlation result and a second correlation result corresponding to the second waveform include: the waveform data without delay, the waveform data delayed by one sampling point, and the waveform data delayed by two sampling points, respectively. Perform a multiply-accumulate operation with the sample point value of the first type of waveform to obtain the first type of advance correlation result, the first type of current correlation result, and the first type of delayed correlation result corresponding to the first type of waveform respectively; The absolute value corresponding to the first type of advance correlation result, the first type of current correlation result, and the first type of delayed correlation result corresponding to the first type of waveform, and the maximum absolute value is used as the first type of waveform corresponding to the first type of waveform. Correlation results; multiply and accumulate the waveform data without delay, the waveform data delayed by one sampling point, and the waveform data delayed by two sampling points with the sample point value of the second type of waveform, respectively. Obtain the second type of advance correlation result, the second type of current correlation result, and the second type of delayed correlation result corresponding to the second type of waveform; obtain the second type of advance correlation result corresponding to the second type of waveform. The absolute value corresponding to the current correlation result and the second type of delayed correlation result, and the largest absolute value is used as the second type of correlation result corresponding to the second type of waveform.

Further, after determining the decoding result corresponding to the data to be decoded in the correlation period corresponding to the actual oversampling number, the method further includes: correlating the first type of lead corresponding to the first type of waveform The absolute value corresponding to the result is compared with the absolute value corresponding to the second type of advance correlation result corresponding to the second type of waveform, and the largest absolute value is used as the absolute value of the advance correlation result; The absolute value corresponding to the current correlation result is compared with the absolute value corresponding to the second current correlation result corresponding to the second waveform, and the maximum absolute value is used as the absolute value of the current correlation result; the first waveform corresponding to The absolute value corresponding to the first type of delayed correlation result is compared with the absolute value corresponding to the second type of delayed correlation result corresponding to the second waveform, and the largest absolute value is used as the absolute value of the delayed correlation result; The maximum value among the absolute value of the preceding correlation result, the absolute value of the current correlation result and the absolute value of the delayed correlation result is determined, and the read address flag is determined; Starting point: An =A _{o +} 2-flag, or An =A _{o +} 3-2*flag, _where An is the actual starting point, A _o is the end point of the current correlation cycle, and flag is the Read the address flag, when the absolute value of the advanced correlation result is the largest, the flag value is 0, when the absolute value of the current correlation result is the largest, the flag value is 1, when the absolute value of the delayed correlation result is the largest, The value of flag is 2; the data to be decoded in the next relevant cycle is extracted from the actual starting point to perform a decoding operation.

Correspondingly, an embodiment of the present invention also provides a decoding device for an RFID reader, the device comprising: a receiving unit for receiving a return signal of an electronic tag; a signal sampling unit for, at a preset sampling frequency, The in-phase signal and the quadrature signal are obtained from the return signal, and the preset sampling frequency is a preset multiple of the return frequency of the return signal; The data phase of the cross signal is obtained to obtain the complex signal corresponding to the return signal; the data to be decoded determination unit is configured to determine the data phase according to the return frequency, the preset sampling frequency, the frequency preset deviation range and the encoding type of the return signal , to determine the actual oversampling number of the data to be decoded and the single pilot tone in the complex signal; the decoding unit is configured to determine the actual oversampling number according to the encoding type of the returned signal and the actual oversampling number The decoding result corresponding to the data to be decoded in the corresponding correlation period.

Further, the signal sampling unit is further configured to convert the in-phase signal and the quadrature signal in the return signal from the analog domain to the digital domain by sampling through an analog-to-digital converter ADC; at the preset sampling frequency, The in-phase signal and the quadrature signal of the digital domain are filtered separately.

Further, the phase calculation unit is further configured to obtain the complex signal F corresponding to the return signal according to F=(I+j*Q)*e ^(-j*Φ) , where I is the in-phase signal, Q is the quadrature signal, Φ is the calculated value of the channel phase, where Φ≈atan(Q/I).

Further, the device further includes: a threshold comparison unit, configured to compare the real part of the complex signal with a preset signal threshold; when the real part of the complex signal is lower than the preset signal threshold, determine The return signal of the electronic tag is an invalid signal, and the decoding operation of the return signal is ended; when the real part of the complex signal is not lower than the preset signal threshold, it is determined that the return signal of the electronic tag is a valid signal , and continue the decoding operation of the return signal.

Further, the to-be-decoded data determination unit is also used to, according to H _l =FS /[ _{F 0} *(1+r)], H _h =FS /[ _{F 0} *(1-r)], to obtain The lower limit H _l and the upper limit H _h of the oversampling number of a single pilot tone in the complex signal, where F ₀ is the return frequency, F _S is the preset sampling frequency, ±r% Presetting the deviation range for the frequency; obtaining the value range of the oversampling number of the single pilot tone in the complex signal according to the lower limit value and the upper limit value of the oversampling number; according to the oversampling number The value range and the encoding type of the returned signal, determine the preamble capture coefficient corresponding to each oversampling number in the value range of the oversampling number; take the preamble capture coefficient corresponding to each oversampling number as The coefficient of the preamble matched filter corresponding to each oversampling number; the real part of the complex signal is matched with the preamble matched filter corresponding to each oversampling number to obtain the matching output value corresponding to each oversampling number ; Take the oversampling number corresponding to the maximum value in the matching output value as the actual oversampling number of the single pilot tone in the complex signal; According to the encoding protocol corresponding to the encoding type, determine the actual oversampling number corresponding preamble, and the data after removing the preamble in the complex signal is used as the data to be decoded.

Further, the decoding unit is further configured to, according to the encoding type of the returned signal and the actual oversampling number, determine the sample point values of the first waveform and the second waveform in the correlation period; In the data to be decoded, extract the waveform data in the relevant period; perform a multiply-accumulate operation on the waveform data with the sample point value of the first type of waveform and the sample point value of the second type of waveform, respectively. Obtain a first type of correlation result corresponding to the first type of waveform and a second type of correlation result corresponding to the second type of waveform; The value is used as the signal decision result; the waveform corresponding to the signal decision result is determined as the decoding result corresponding to the to-be-decoded data in the correlation period.

Further, the decoding unit is further configured to separate the waveform data without delay, the waveform data delayed by one sample point, and the waveform data delayed by two sample points with the sample points of the first waveform respectively. Multiply and accumulate the values to obtain the first type of advance correlation result corresponding to the first type of waveform, the first type of current correlation result, and the first type of delayed correlation result; obtain the first type of waveform corresponding to the first type of waveform The absolute value corresponding to the leading correlation result, the first type of current correlation result, and the first type of delayed correlation result, and the maximum absolute value is taken as the first type of correlation result corresponding to the first type of waveform; The waveform data, the waveform data delayed by one sample point, and the waveform data delayed by two sample points are respectively multiplied and accumulated with the sample point value of the second waveform to obtain the first waveform corresponding to the second waveform. Two types of advance correlation results, the second type of current correlation results, and the second type of delayed correlation results; obtain the second type of advanced correlation results, the second type of current correlation results, and the second type of delayed correlation results corresponding to the second type of waveform The absolute value corresponding to the result, and the largest absolute value is used as the second correlation result corresponding to the second waveform.

Further, the device further includes: a starting point calibration unit, configured to compare the absolute value corresponding to the first type of advance correlation result corresponding to the first type of waveform with the second type of advance correlation result corresponding to the second type of waveform The corresponding absolute values are compared, and the largest absolute value is used as the absolute value of the leading correlation result; the absolute value corresponding to the first type of current correlation result corresponding to the first type of waveform and the second type of waveform corresponding to the second type of waveform. The absolute values corresponding to the current correlation results are compared, and the maximum absolute value is used as the absolute value of the current correlation result; the absolute value corresponding to the first type of delayed correlation result corresponding to the first type of waveform corresponds to the second type of waveform. The absolute value corresponding to the second type of delayed correlation result is compared, and the largest absolute value is used as the absolute value of the delayed correlation result; The maximum value of , determine the read address flag; according to any one of the following formulas, obtain the actual starting point of the data to be decoded in the next relevant cycle, A _n =A _o +2-flag, or An =A _{o +} 3- 2*flag, wherein, A _n is the actual starting point, A _o is the end point of the current correlation cycle, flag is the read address flag, and when the absolute value of the lead correlation result is the largest, the value of flag is 0, When the absolute value of the current correlation result is the largest, the flag value is 1, and when the absolute value of the delayed correlation result is the largest, the flag value is 2; Decode data for decoding operation.

Correspondingly, an embodiment of the present invention further provides an RFID reader/writer, and the system includes: the above-mentioned decoding device for an RFID reader/writer.

Correspondingly, an embodiment of the present invention further provides a machine-readable storage medium, where instructions are stored on the machine-readable storage medium, and the instructions are used to cause a machine to execute the above-described decoding method for an RFID reader/writer.

Through the above technical solution, the in-phase signal and the quadrature signal are obtained from the return signal returned by the electronic tag at a preset sampling frequency, and the return signal is obtained according to the data phase of the in-phase signal and the quadrature signal. The corresponding complex signal, and then according to the return frequency, the preset sampling frequency, the frequency preset deviation range and the encoding type of the return signal, determine the actual data to be decoded and the single pilot tone in the complex signal. The number of oversampling, and then the decoding result corresponding to the data to be decoded in the correlation period corresponding to the actual number of oversampling is determined according to the encoding type of the returned signal and the actual number of oversampling. The embodiment of the present invention is suitable for the decoding of data of different encoding types (FM0/miller2/miller4/miller8), which enhances the versatility of decoding. At the same time, the time-domain matched filtering technology is used to capture the signal preamble and obtain the data to be decoded, which has strong advantages. weak signal detection capability. In addition, using the in-phase and quadrature signals for phase calculation and rotation, and concentrating the signal energy into one channel, can not only improve the signal-to-noise ratio, but also save processing resources, and can also overcome the relative movement of the RFID reader and the electronic tag. The problem of fast switching of strong signals.

Other features and advantages of embodiments of the present invention will be described in detail in the detailed description section that follows.

Description of drawings

The accompanying drawings are used to provide a further understanding of the embodiments of the present invention, and constitute a part of the specification, and are used to explain the embodiments of the present invention together with the following specific embodiments, but do not constitute limitations to the embodiments of the present invention. In the attached image:

1 is a schematic flowchart of a decoding method for an RFID reader provided by an embodiment of the present invention;

2 is a schematic structural diagram of preamble acquisition and actual oversampling number determination provided by an embodiment of the present invention;

3 is a schematic diagram of a related processing structure of a first waveform provided by an embodiment of the present invention;

4 is a schematic diagram of a related processing structure of a second waveform provided by an embodiment of the present invention;

5 is a schematic structural diagram of an implementation of error calibration of an actual starting point provided by an embodiment of the present invention;

6 is a schematic structural diagram of a decoding device for an RFID reader provided by an embodiment of the present invention;

7 is a schematic structural diagram of another decoding device for an RFID reader provided by an embodiment of the present invention;

FIG. 8 is a schematic structural diagram of another decoding device for an RFID reader/writer provided by an embodiment of the present invention.

Detailed ways

The specific implementations of the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific implementation manners described herein are only used to illustrate and explain the embodiments of the present invention, and are not used to limit the embodiments of the present invention.

FIG. 1 is a schematic flowchart of a decoding method for an RFID reader provided by an embodiment of the present invention. The embodiment of the present invention is applicable to decoding of FM0, miller2, miller4, and miller8 encoding type data. As shown in Figure 1, the method includes the following steps:

Step 110, receiving the return signal of the electronic tag.

In the embodiment of the present invention, for passive RFID, after the RFID reader transmits the microwave signal to the electronic tag, the electronic tag obtains energy through the electromagnetic induction coil to supply power to itself for a short time, and returns the return signal to the RFID reading and writing device.

Step 120: Obtain an in-phase signal and a quadrature signal from the return signal at a preset sampling frequency, where the preset sampling frequency is a preset multiple of the return frequency of the return signal.

After receiving the return signal of the electronic tag, an analog-to-digital converter (Analog to Digital Converter, ADC) is used for sampling, and the in-phase signal and the quadrature signal in the return signal are transformed from the analog domain to the digital domain. Then, at the preset sampling frequency, the in-phase signal and the quadrature signal in the digital domain are filtered respectively. Wherein, since the return frequency of the return signal fluctuates up and down, in order to facilitate subsequent processing of the return signal and accurately extract the actual return frequency of the return signal, the preset sampling frequency is a preset sampling frequency of the return frequency of the return signal. Set the multiple, for example, the preset multiple is greater than or equal to 16. In addition, the filtering operation can also filter out low-frequency noise, part of DC, and high-frequency components.

Step 130: Obtain a complex signal corresponding to the return signal according to the data phases of the in-phase signal and the quadrature signal.

Among them, the use of in-phase and quadrature signals for phase calculation and rotation, so as to concentrate the signal energy into one channel, can improve the signal-to-noise ratio and save processing resources, and can also overcome the relative movement of the RFID reader and the electronic tag. The problem of fast transformation of strong signals.

Specifically, according to F=(I+j*Q)*e ^(-j*Φ) , the complex signal F corresponding to the return signal is obtained, where I is the in-phase signal and Q is the quadrature signal , Φ is the calculated value of the channel phase, where Φ≈atan(Q/I).

After the above phase calculation and phase rotation, most of the signals are distributed in the real part of the complex signal, and there are only a few signals in the imaginary part, and the signals in the imaginary part can be ignored in subsequent processing.

In addition, in order to improve the validity of decoding, the validity judgment may be performed on the complex signal, so as to determine whether it is a valid signal. For example, the real part of the complex signal is compared to a preset signal threshold. The preset signal threshold may be 3 to 5 times the set noise power value. Then, when the real part of the complex signal is lower than the preset signal threshold, it is determined that the return signal of the electronic tag is an invalid signal, and the decoding operation of the return signal is ended. When the real part of the complex signal is not lower than the preset signal threshold, it is determined that the return signal of the electronic tag is a valid signal, and the following decoding operation of the return signal can be continued.

Step 140, according to the return frequency, the preset sampling frequency, the frequency preset deviation range and the encoding type of the return signal, determine the actual oversampling number of the data to be decoded and the single pilot tone in the complex signal .

Wherein, it is determined that the data to be decoded in the complex signal is actually the preamble that captures the real part of the complex signal, and the data to be decoded is the data to be decoded after the preamble is removed. When capturing the preamble, it is necessary to determine the coefficient of the preamble matched filter, that is, to determine the preamble capture coefficient. Different coding types correspond to different preamble capture coefficients. If the coding type is MILLER coding, the preamble capture coefficient can be the coefficient formed by the preamble "010111" through MILLER coding or the coefficient formed by the MILLER coding of the preamble part; if the coding type is FM0 coding, the preamble capture coefficient can be the FM0 preamble Structure "1010v1", also part of "1010v1". The preamble capture uses a time-domain matched filter to process the received signal, and the output time of the correlation peak is the time when the preamble of the received signal appears.

First, the preamble capture coefficients need to be determined. According to H _l =F _S /[F ₀ *(1+r)], H _h =F _S /[F ₀ *(1-r)], the oversampling number of the single pilot tone in the complex signal is obtained The lower limit value H _l and the upper limit value H _h of , where F ₀ is the return frequency, F _S is the preset sampling frequency, and ±r% is the frequency preset deviation range determined according to the coding protocol. According to the lower limit value and the upper limit value of the oversampling number, the value range (H _l , H _h ) of the oversampling number of the single pilot tone in the complex signal is obtained. Wherein, when calculating the oversampling number, there will be a decimal value, and after rounding, the oversampling number in the value range of the oversampling number is obtained. In order to cover the frequency deviation range of the return frequency, it is necessary to set up oversampling several preamble matched filters in parallel to perform preamble capture, and the coefficient of each preamble matched filter is the preamble capture coefficient. And according to the value range of the oversampling number and the encoding type of the returned signal, the preamble capture coefficient corresponding to each oversampling number in the value range of the oversampling number can be determined. Then, the real part of the complex signal is matched with the preamble matched filter corresponding to each oversampling number to obtain a matching output value corresponding to each oversampling number. A number of oversampled matching output values are compared, and the oversampling number corresponding to the maximum value in the matching output value is used as the actual oversampling number of the single pilot tone in the complex signal. The actual return frequency of the return signal can also be determined from the actual oversampling number, that is, the ratio of the preset sampling frequency to the actual oversampling number, that is, the actual return frequency. Then, according to the encoding protocol corresponding to the encoding type, the preamble corresponding to the actual oversampling number is determined, and the data after removing the preamble in the complex signal is used as the data to be decoded.

The execution process of step 104 is described below by taking the FM0 encoding type as an example. Assuming that the return frequency of the return signal is 320KHz, the preset sampling frequency is 6400K, and according to the encoding protocol, the preset deviation range of the frequency is ±15%, then the The value range of the oversampling number of the single pilot tone in the complex signal is (6400/(320*1.15), 6400/(320*0.85)), that is, the oversampling number includes 17, 18, 19, 20, 21 , 22, 23, and 24 have a total of 8 oversampling numbers, then 8 preamble matched filters need to be set in parallel to capture the preamble.

Then, according to the encoding protocol of the FM0 encoding type, the preamble capture coefficients corresponding to the 8 oversampling numbers are obtained, that is, the coefficients of the 8 preamble matched filters:

1) The coefficients of the preamble matched filter corresponding to the oversampling number of a single pilot tone is 17:

11111111111111111_00000000000000000_00000000111111111_00000000000000000_111111111100000000_1111111111111111

2) The number of oversampling of a single pilot tone is 18. The coefficients of the preamble matched filter are:

111111111111111111_000000000000000000_000000000111111111_000000000000000000_111111111000000000_111111111111111111

3) The oversampling number of a single pilot tone is 19. The coefficients of the preamble matched filter are:

1111111111111111111_0000000000000000000_0000000001111111111_0000000000000000000_1111111111000000000_111111111111111111

4) The coefficient of the preamble matched filter corresponding to the oversampling number of a single pilot tone is 20:

111111111111111111111_00000000000000000000_00000000001111111111_00000000000000000000_111111111110000000000_1111111111111111111

5) The number of oversampling of a single pilot tone is 21, and the coefficients of the preamble matched filter corresponding to:

111111111111111111111_000000000000000000000_000000000011111111111_000000000000000000000_1111111111110000000000_1111111111111111

6) The coefficient of the preamble matched filter corresponding to the oversampling number of a single pilot tone is 22:

1111111111111111111111_0000000000000000000000_0000000000011111111111_0000000000000000000000_1111111111100000000111111111111111111111111111111_000000000000000000000

7) The coefficients of the preamble matched filter corresponding to the oversampling number of a single pilot tone is 23:

11111111111111111111111_00000000000000000000000_000000000000111111111_00000000000000000000000_1111111111111000001111111111111111111111111111111111111111111111111111111111111111111111111

8) The oversampling number of a single pilot tone is 24. The coefficients of the preamble matched filter are:

111111111111111111111111_000000000000000000000000_000000000000011111111111_000000000000000000000000_111111111111000000000000_111111111111111111111111

In addition, during specific implementation, 0 in the above-mentioned preamble acquisition coefficient is represented by -1.

After the coefficients of the 8 preamble matched filters are determined, the real part of the complex signal can be matched with the 8 preamble matched filters. As shown in Figure 2, it is a schematic diagram of the structure of the preamble capture and the actual number of oversampling, in which 8 preamble matched filters are set in parallel, and each preamble matched filter is followed by a corresponding matched output detector. The matching output detector obtains the matching output value corresponding to each oversampling number, and the maximum matching output value is obtained by the maximum matching output detector, and the oversampling number corresponding to the maximum value is used as the complex signal. The actual number of oversampling for a single pilot tone. Afterwards, the preamble corresponding to the actual oversampling number may be determined according to the coding protocol corresponding to the coding type, and the data after removing the preamble in the complex signal is used as the data to be decoded.

Step 150: Determine a decoding result corresponding to the data to be decoded in the correlation period corresponding to the actual oversampling number according to the encoding type of the returned signal and the actual oversampling number.

After the actual oversampling number is obtained, the sample point values of the first waveform and the second waveform in the relevant period may be determined according to the encoding type of the returned signal and the actual oversampling number, that is, the determination of the The sample point values of waveform 0 and waveform 1 in the correlation period, wherein the correlation period is the time period of multiplying and accumulating, that is, the time period of multiplying and accumulating in FIG. 3 and FIG. 4 .

For FM0 encoding type, the number of sample point values in one correlation cycle is the actual oversampling number; for MILLER2 encoding type, the number of sample point values in one correlation cycle is twice the actual oversampling number. ; For MILLER4 encoding type, the number of sample point values of a correlation cycle is 4 times the actual oversampling number; For MILLER8 encoding type, the number of sample point values of one correlation cycle is the actual oversampling number 8 times the number.

In addition, in order to decode the to-be-decoded data, it is necessary to first obtain the sample values corresponding to waveform 0 and waveform 1 corresponding to the data to be decoded.

Taking FM0 encoding as an example, the generation method of waveform 0 and waveform 1 will be described. Let the actual number of oversampling in a correlation cycle be N, if N is an even number, waveform 1 in a correlation cycle: N data sample values are all "1"; waveform 0 in a correlation cycle: there are N in the first half of the correlation cycle /2 "1" and N/2 "-1" in the second half of the relevant period. If N is an odd number, waveform 1 in one correlation cycle: N data sample values are all "1"; waveform 0 in one correlation cycle: There are (N-1)/2 "1"s in the first half of the correlation cycle, and the correlation There are (N+1)/2 "-1"s in the second half of the cycle.

Taking the miller2 encoding as an example, the generation method of waveform 0 and waveform 1 will be described. Let the actual number of oversampling for a correlation cycle be N,

1) If N is even and N/2 is even, waveform 1 in one correlation period: the first 1/4 part of the correlation period has N/4 "1"s, the second 1/4 part of the correlation period There are N/4 "-1"s, the third 1/4 part of the correlation period has N/4 "-1"s, the fourth 1/4 part of the correlation period has N/4 "1"s; a Waveform 0 in the correlation period: the first 1/4 part of the correlation period has N/4 "1"s, the second 1/4 part of the correlation period has N/4 "-1"s, the first 1/4 part of the correlation period has N/4 "-1" The three 1/4 parts have N/4 "1"s, and the fourth 1/4 part of the relevant period has N/4 "-1"s.

2) If N is even and N/2 is odd, waveform 1 in one correlation period: the first 1/4 part of the correlation period has (N-2)/4 "1"s, the second of the correlation period has (N-2)/4 "1"s The 1/4 part has (N+2)/4 "-1"s, the third 1/4 part of the relevant period has (N-2)/4 "-1"s, the fourth 1/4 of the relevant period 4 parts have (N+2)/4 "1"s; waveform 0 in one correlation cycle: the first 1/4 part of the correlation cycle has (N-2)/4 "1"s, the first 1/4 part of the correlation cycle has (N-2)/4 "1", the Two 1/4 parts have (N+2)/4 "-1"s, the third 1/4 part of the relevant period has (N-2)/4 "1"s, the fourth 1 of the relevant period The /4 part has (N+2)/4 "-1"s.

3) If N is odd and (N-1)/2 is even, waveform 1 in one correlation period: the first 1/4 part of the correlation period has (N-1)/4 "1"s, the correlation period The second 1/4 part has (N-1)/4 "-1"s, the third 1/4 part of the relevant period has (N-1)/4 "-1"s, the first 1/4 part of the relevant period has (N-1)/4 "-1" Four 1/4 parts have (N+3)/4 "1"s; waveform 0 in one correlation cycle: the first 1/4 part of the correlation cycle has (N-1)/4 "1"s, The second 1/4 part of the relevant period has (N-1)/4 "-1"s, the third 1/4 part of the relevant period has (N-1)/4 "1"s, and the The fourth 1/4 part has (N+3)/4 "-1"s.

4) If N is odd and (N-1)/2 is odd, waveform 1 in one correlation period: the first 1/4 part of the correlation period has (N-3)/4 "1"s, the correlation period The second 1/4 part has (N+1)/4 "-1"s, the third 1/4 part of the relevant period has (N+1)/4 "-1"s, the first 1/4 part of the relevant period has (N+1)/4 "-1" Four 1/4 parts have (N+1)/4 "1"s; waveform 0 in one correlation cycle: the first 1/4 part of the correlation cycle has (N-3)/4 "1"s, The second 1/4 part of the relevant period has (N+1)/4 "-1"s, the third 1/4 part of the relevant period has (N+1)/4 "1"s, and the The fourth 1/4 part has (N+1)/4 "-1"s.

In the same way, in the case where the actual oversampling number of a relevant period has been determined, the generation method of the waveform 0 and the waveform 1 encoded by the miller4 and the miller8 can also be obtained, which will not be repeated here.

After the sample point values of the first waveform and the second waveform corresponding to each coding type have been acquired, correlation matching can be performed with the waveform data in the correlation period in the data to be decoded.

The waveform data is respectively multiplied and accumulated with the sample point value of the first waveform and the sample point value of the second waveform to obtain the first correlation corresponding to the first waveform. results and a second correlation result corresponding to the second waveform.

Specifically, as shown in FIG. 3 and FIG. 4 , the correlation processing structure of the first waveform and the correlation processing structure of the second waveform are shown.

Wherein, as shown in FIG. 3 , the waveform data without delay, the waveform data delayed by one sampling point, and the waveform data delayed by two sampling points are respectively multiplied by the sample value of the first waveform The accumulation operation is performed to obtain the first type of advance correlation result, the first type of current correlation result, and the first type of delayed correlation result corresponding to the first type of waveform, respectively. Then, acquire the absolute values corresponding to the first type of advance correlation result, the first type of current correlation result, and the first type of delayed correlation result corresponding to the first type of waveform, and use the largest absolute value as the first type of waveform The corresponding first correlation result.

As shown in FIG. 4 , the waveform data without delay, the waveform data delayed by one sampling point, and the waveform data delayed by two sampling points are respectively multiplied and accumulated with the sample value of the second waveform. , respectively obtain the second type of advance correlation result, the second type of current correlation result, and the second type of delayed correlation result corresponding to the second type of waveform. Then, obtain the absolute values corresponding to the second type of advance correlation result, the second type of current correlation result, and the second type of delayed correlation result corresponding to the second type of waveform, and use the largest absolute value as the second type of waveform The corresponding second correlation result.

Since there are "1" and "-1" in the sample points in the waveform, there may be negative values after multiplying and accumulating. Therefore, the absolute value of the above correlation result is taken so that the data for subsequent comparisons are all positive values.

After that, the maximum value of the first correlation result and the second correlation result is used as the signal decision result, and the waveform corresponding to the signal decision result is determined as the data to be decoded in the correlation period corresponding decoding result. That is, according to the first correlation result (corresponding to waveform 0) and the second correlation result (corresponding to waveform 1), the decision of data 0 or data 1 is performed. If the first correlation result is greater than the second correlation result, it is determined that the decoding result corresponding to the data to be decoded in the correlation period is 0; otherwise, if the second correlation result is greater than the first correlation result, the correlation period is determined The decoding result corresponding to the data to be decoded is 1, that is, the decoding result of the data to be decoded in the first correlation period after the preamble is obtained. Then, continue decoding the data to be decoded in the next relevant period through step 105 .

However, due to accumulated error and data rate jitter, when decoding the data to be decoded in the correlation period, the wrong starting point and accumulated error will lead to data decoding errors. Therefore, the decoding of the to-be-decoded data in each correlation period After that, it is necessary to perform error calibration on the actual starting point of the next relevant cycle.

The implementation structure of the error calibration at the actual starting point is shown in FIG. 5 . ) is compared with the absolute value corresponding to the second type of advance correlation result corresponding to the second waveform (ie, the absolute value corresponding to the second type of advance correlation result of waveform 1), and the largest absolute value is taken as the absolute value of the advance correlation result For example, if the absolute value corresponding to the first type of lead correlation result of waveform 0 is greater than the absolute value of the second type of lead correlation result of waveform 1, then the absolute value of the lead correlation result corresponds to the first type of lead correlation result of waveform 0 The absolute value of , and vice versa.

The absolute value corresponding to the first type of current correlation result corresponding to the first type of waveform (that is, the absolute value corresponding to the first type of current correlation result of waveform 0) and the second type of current correlation corresponding to the second type of waveform. The absolute value corresponding to the result (that is, the absolute value corresponding to the second current correlation result of waveform 1) is compared, and the maximum absolute value is taken as the absolute value of the current correlation result.

The absolute value corresponding to the first type of delayed correlation result corresponding to the first type of waveform (that is, the absolute value corresponding to the first type of delayed correlation result of waveform 0) and the second type of waveform corresponding to the second type of waveform. The absolute values corresponding to the delayed correlation results (that is, the absolute values corresponding to the second type of delayed correlation results of waveform 1) are compared, and the largest absolute value is taken as the absolute value of the delayed correlation results.

Then, the read address flag is determined according to the maximum value among the absolute value of the early correlation result, the absolute value of the current correlation result, and the absolute value of the late correlation result, wherein, when the absolute value of the early correlation result is the largest, the read address The flag takes a value of 0, when the absolute value of the current correlation result is the largest, the read address flag takes a value of 1, and when the absolute value of the delayed correlation result is the largest, the read address flag takes a value of 2. The read address flag is shown as an input parameter for the generation of the actual starting point. Obtain the actual starting point of the data to be decoded for the next relevant cycle according to any of the following formulas:

An =A _{o +} 2-flag, or An =A _{o +} 3-2*flag,

Wherein, An _is the actual start point, A _o is the end point of the current relevant cycle, and flag is the read address flag.

Further, extract the data to be decoded in the next relevant cycle from the actual starting point and continue the decoding operation, that is, execute step 105 to compare the data to be decoded in the next relevant cycle with the first waveform corresponding to the encoding type. Correlation matching is performed between the sample point value and the sample point value of the second waveform, so that the decoding result of the data to be decoded in the next correlation period is determined according to the matching result.

Through the embodiments of the present invention, the decoding signal-to-noise ratio of the RFID reader/writer can be greatly improved. Especially in scenarios with severe environmental interference and large multipath fading, RFID readers have extremely sensitive signal detection capabilities and excellent decoding capabilities. In the embodiment of the present invention, the sampling deviation can be dynamically adjusted in the decoding stage to avoid the decoding error caused by the jitter of the return signal frequency of the electronic tag. At the end of a correlation period, the dynamic adjustment is achieved by changing the read address of the waveform correlation processing structure. Sampling bias, which determines the actual starting point for the next correlation cycle. In addition, the decoding of data of different encoding types (FM0/miller2/miller4/miller8) can be implemented by the embodiments of the present invention, which is convenient for saving processing resources. The time-domain matched filtering technique is used to estimate the number of oversampling to provide parameters for correlation demodulation. In addition, the time-domain matched filtering technology is used to capture the signal preamble to obtain the data to be decoded, which has a strong weak signal detection capability. In the decoding process of the embodiment of the present invention, the in-phase and quadrature signals are used for phase calculation and rotation to generate a complex signal, which can not only improve the signal-to-noise ratio, but also save processing resources, and can overcome the problem of RFID readers and electronic devices. The problem of rapid change of strong signal caused by the relative movement of the label.

Correspondingly, FIG. 6 is a schematic structural diagram of a decoding device for an RFID reader provided by an embodiment of the present invention. As shown in FIG. 6 , the device 60 includes: a receiving unit 61 for receiving a return signal of the electronic tag; a signal sampling unit 62 for obtaining an in-phase signal and a positive signal from the return signal at a preset sampling frequency The preset sampling frequency is a preset multiple of the return frequency of the return signal; the phase calculation unit 63 is configured to obtain the return signal according to the data phases of the in-phase signal and the quadrature signal The corresponding complex signal; the to-be-decoded data determination unit 64 is configured to determine the to-be-decoded data in the complex signal according to the return frequency, the preset sampling frequency, the frequency preset deviation range and the encoding type of the return signal The actual oversampling number of data and a single pilot tone; the decoding unit 65 is configured to determine, according to the encoding type of the returned signal and the actual oversampling number, the to-be-to-be-sampled number in the relevant period corresponding to the actual oversampling number The decoding result corresponding to the decoded data.

Further, the signal sampling unit is further configured to convert the in-phase signal and the quadrature signal in the return signal from the analog domain to the digital domain by sampling through an analog-to-digital converter ADC; at the preset sampling frequency, The in-phase signal and the quadrature signal of the digital domain are filtered separately.

Further, the phase calculation unit is further configured to obtain the complex signal F corresponding to the return signal according to F=(I+j*Q)*e ^(-j*Φ) , where I is the in-phase signal, Q is the quadrature signal, Φ is the calculated value of the channel phase, where Φ≈atan(Q/I).

Further, as shown in FIG. 7 , the apparatus further includes: a threshold comparison unit 66, configured to compare the real part of the complex signal with a preset signal threshold; when the real part of the complex signal is lower than the When the signal threshold is preset, it is determined that the return signal of the electronic tag is an invalid signal, and the decoding operation of the return signal is ended; when the real part of the complex signal is not lower than the preset signal threshold, it is determined that the electronic The returned signal of the tag is a valid signal, and the decoding operation of the returned signal is continued.

Further, the to-be-decoded data determination unit is also used to, according to H _l =FS /[ _{F 0} *(1+r)], H _h =FS /[ _{F 0} *(1-r)], to obtain The lower limit H _l and the upper limit H _h of the oversampling number of a single pilot tone in the complex signal, where F ₀ is the return frequency, F _S is the preset sampling frequency, ±r% Presetting the deviation range for the frequency; obtaining the value range of the oversampling number of the single pilot tone in the complex signal according to the lower limit value and the upper limit value of the oversampling number; according to the oversampling number The value range and the encoding type of the returned signal, determine the preamble capture coefficient corresponding to each oversampling number in the value range of the oversampling number; take the preamble capture coefficient corresponding to each oversampling number as The coefficient of the preamble matched filter corresponding to each oversampling number; the real part of the complex signal is matched with the preamble matched filter corresponding to each oversampling number to obtain the matching output value corresponding to each oversampling number ; Take the oversampling number corresponding to the maximum value in the matching output value as the actual oversampling number of the single pilot tone in the complex signal; According to the encoding protocol corresponding to the encoding type, determine the actual oversampling number corresponding preamble, and the data after removing the preamble in the complex signal is used as the data to be decoded.

Further, the decoding unit is further configured to, according to the encoding type of the returned signal and the actual oversampling number, determine the sample point values of the first waveform and the second waveform in the correlation period; In the data to be decoded, extract the waveform data in the relevant period; perform a multiply-accumulate operation on the waveform data with the sample point value of the first type of waveform and the sample point value of the second type of waveform, respectively. Obtain a first type of correlation result corresponding to the first type of waveform and a second type of correlation result corresponding to the second type of waveform; The value is used as the signal decision result; the waveform corresponding to the signal decision result is determined as the decoding result corresponding to the to-be-decoded data in the correlation period.

Further, the decoding unit is further configured to separate the waveform data without delay, the waveform data delayed by one sample point, and the waveform data delayed by two sample points with the sample points of the first waveform respectively. Multiply and accumulate the values to obtain the first type of advance correlation result corresponding to the first type of waveform, the first type of current correlation result, and the first type of delayed correlation result; obtain the first type of waveform corresponding to the first type of waveform The absolute value corresponding to the leading correlation result, the first type of current correlation result, and the first type of delayed correlation result, and the maximum absolute value is taken as the first type of correlation result corresponding to the first type of waveform; The waveform data, the waveform data delayed by one sample point, and the waveform data delayed by two sample points are respectively multiplied and accumulated with the sample point value of the second waveform to obtain the first waveform corresponding to the second waveform. Two types of advance correlation results, the second type of current correlation results, and the second type of delayed correlation results; obtain the second type of advanced correlation results, the second type of current correlation results, and the second type of delayed correlation results corresponding to the second type of waveform The absolute value corresponding to the result, and the largest absolute value is used as the second correlation result corresponding to the second waveform.

Further, as shown in FIG. 8 , the device further includes: a starting point calibration unit 67, configured to correspond the absolute value corresponding to the first type of lead correlation result corresponding to the first type of waveform to the second type of waveform The absolute value corresponding to the second type of advanced correlation result is compared, and the largest absolute value is used as the absolute value of the advanced correlation result; the absolute value corresponding to the first type of current correlation result corresponding to the first type of waveform and the second Compare the absolute value corresponding to the second current correlation result corresponding to the first waveform, and use the largest absolute value as the absolute value of the current correlation result; compare the absolute value corresponding to the first delayed correlation result corresponding to the first waveform with The absolute values corresponding to the second type of delayed correlation result corresponding to the second type of waveform are compared, and the maximum absolute value is used as the absolute value of the delayed correlation result; according to the absolute value of the advanced correlation result, the absolute value of the current correlation result and The maximum value in the absolute value of the delayed correlation result is determined as the read address flag; according to any one of the following formulas, the actual starting point of the data to be decoded in the next correlation cycle is obtained: A _n =A _o +2-flag, Or An =A _{o +} 3-2*flag, wherein, An _is the actual starting point, A _o is the end point of the current correlation cycle, and flag is the read address flag, when the absolute value of the lead correlation result is When the absolute value of the current correlation result is the largest, the flag value is 1, and when the absolute value of the delayed correlation result is the largest, the flag value is 2; from the actual starting point Extract the to-be-decoded data of the next correlation cycle to perform a decoding operation.

For the specific implementation process of the decoding device for an RFID reader/writer, refer to the above-mentioned processing procedure of the decoding method for an RFID reader/writer.

Correspondingly, an embodiment of the present invention further provides an RFID reader/writer, and the system includes: the above-mentioned decoding device for an RFID reader/writer.

Correspondingly, an embodiment of the present invention further provides a machine-readable storage medium, where instructions are stored on the machine-readable storage medium, and the instructions are used to cause a machine to execute the above-described decoding method for an RFID reader/writer.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present application. It will be understood that each flow and/or block in the flowcharts and/or block diagrams, and combinations of flows and/or blocks in the flowcharts and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to the processor of a general purpose computer, special purpose computer, embedded processor or other programmable data processing device to produce a machine such that the instructions executed by the processor of the computer or other programmable data processing device produce Means for implementing the functions specified in one or more of the flowcharts and/or one or more blocks of the block diagrams.

In a typical configuration, a device includes one or more processors (CPUs), memory, and a bus. Devices may also include input/output interfaces, network interfaces, and the like.

Memory may include non-persistent memory in computer readable media, random access memory (RAM) and/or non-volatile memory, such as read only memory (ROM) or flash memory (flash RAM), the memory including at least one memory chip. Memory is an example of a computer-readable medium.

Computer-readable media includes both persistent and non-permanent, removable and non-removable media, and storage of information may be implemented by any method or technology. Information may be computer readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read only memory (ROM), Electrically Erasable Programmable Read Only Memory (EEPROM), Flash Memory or other memory technology, Compact Disc Read Only Memory (CD-ROM), Digital Versatile Disc (DVD) or other optical storage, Magnetic tape cassettes, magnetic tape magnetic disk storage or other magnetic storage devices or any other non-transmission medium that can be used to store information that can be accessed by a computing device. As defined herein, computer-readable media does not include transitory computer-readable media, such as modulated data signals and carrier waves.

It should also be noted that the terms "comprising", "comprising" or any other variation thereof are intended to encompass a non-exclusive inclusion such that a process, method, article or device comprising a series of elements includes not only those elements, but also Other elements not expressly listed, or which are inherent to such a process, method, article of manufacture, or apparatus are also included. Without further limitation, an element qualified by the phrase "comprising a..." does not preclude the presence of additional identical elements in the process, method, article of manufacture or apparatus that includes the element.

It will be appreciated by those skilled in the art that the embodiments of the present application may be provided as a method, a system or a computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.

The above are merely examples of the present application, and are not intended to limit the present application. Various modifications and variations of this application are possible for those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this application shall be included within the scope of the claims of this application.

Claims (18)

1. a decoding method for an RFID reader, characterized in that the method comprises: Receive the return signal of the electronic tag; obtaining an in-phase signal and a quadrature signal from the return signal at a preset sampling frequency, where the preset sampling frequency is a preset multiple of the return frequency of the return signal; obtaining a complex signal corresponding to the return signal according to the data phase of the in-phase signal and the quadrature signal; According to the return frequency, the preset sampling frequency, the frequency preset deviation range and the encoding type of the return signal, determine the actual oversampling number of the data to be decoded and the single pilot tone in the complex signal; According to the encoding type of the returned signal and the actual oversampling number, the decoding result corresponding to the data to be decoded in the correlation period corresponding to the actual oversampling number is determined. 2 . The decoding method for an RFID reader according to claim 1 , wherein the obtaining an in-phase signal and a quadrature signal from the return signal at a preset sampling frequency comprises: 2 . The in-phase signal and the quadrature signal in the return signal are transformed from the analog domain to the digital domain by sampling through the analog-to-digital converter ADC; The in-phase signal and the quadrature signal in the digital domain are filtered separately at the preset sampling frequency. 3 . The decoding method for an RFID reader according to claim 1 , wherein the complex signal corresponding to the return signal is obtained according to the data phase of the in-phase signal and the quadrature signal. 4 . include: According to F=(I+j*Q)*e ^(-j*Φ) , the complex signal F corresponding to the return signal is obtained, where I is the in-phase signal, Q is the quadrature signal, and Φ is the Calculated value of the channel phase, where Φ≈atan(Q/I). 4 . The decoding method for an RFID reader according to claim 1 , wherein in the data phase according to the in-phase signal and the quadrature signal, the complex corresponding to the return signal is obtained. 5 . After the signal, the method further includes: comparing the real part of the complex signal with a preset signal threshold; When the real part of the complex signal is lower than the preset signal threshold, determine that the return signal of the electronic tag is an invalid signal, and end the decoding operation of the return signal; When the real part of the complex signal is not lower than the preset signal threshold, it is determined that the return signal of the electronic tag is a valid signal, and the decoding operation of the return signal is continued. 5 . The decoding method for an RFID reader according to claim 1 , wherein the encoding according to the return frequency, the preset sampling frequency, the frequency preset deviation range, and the return signal. 6 . type, to determine the actual oversampling number of the data to be decoded and the single pilot tone in the complex signal, including: According to H _l =F _S /[F ₀ *(1+r)], H _h =F _S /[F ₀ *(1-r)], the oversampling number of the single pilot tone in the complex signal is obtained The lower limit value H _l and the upper limit value H _h of , where F ₀ is the return frequency, F _S is the preset sampling frequency, and ±r% is the frequency preset deviation range; According to the lower limit value and the upper limit value of the oversampling number, the value range of the oversampling number of the single pilot tone in the complex signal is obtained; Determine the preamble capture coefficient corresponding to each oversampling number in the value range of the oversampling number according to the value range of the oversampling number and the encoding type of the return signal; Taking the preamble capture coefficient corresponding to each oversampling number as the coefficient of the preamble matched filter corresponding to each oversampling number; Matching the real part of the complex signal with the preamble matched filter corresponding to each oversampling number to obtain a matching output value corresponding to each oversampling number; Taking the oversampling number corresponding to the maximum value in the matching output value as the actual oversampling number of the single pilot tone in the complex signal; According to the encoding protocol corresponding to the encoding type, the preamble corresponding to the actual oversampling number is determined, and the data after removing the preamble in the complex signal is used as the data to be decoded. 6 . The decoding method for an RFID reader according to claim 1 , wherein, according to the encoding type of the returned signal and the actual oversampling number, determine the corresponding actual oversampling number. 7 . The decoding results corresponding to the data to be decoded in the relevant period include: Determine the sample point values of the first waveform and the second waveform in the correlation period according to the encoding type of the returned signal and the actual oversampling number; In the data to be decoded, extract the waveform data in the relevant period; Multiply and accumulate the waveform data with the sample point value of the first type of waveform and the sample point value of the second type of waveform, respectively, to obtain the first type of correlation result corresponding to the first type of waveform and a second correlation result corresponding to the second waveform; Taking the maximum value of the first correlation result and the second correlation result as a signal decision result; The waveform corresponding to the signal decision result is determined as the decoding result corresponding to the data to be decoded in the correlation period. 7 . The decoding method for an RFID reader according to claim 6 , wherein the waveform data is respectively correlated with the sample point value of the first waveform and the sample value of the second waveform. 8 . The sample value is multiplied and accumulated to obtain a first correlation result corresponding to the first waveform and a second correlation result corresponding to the second waveform, including: Multiply and accumulate the waveform data without delay, the waveform data delayed by one sampling point, and the waveform data delayed by two sampling points with the sample point value of the first type of waveform, respectively, to obtain the first waveform data. The first type of advance correlation result, the first type of current correlation result, and the first type of delayed correlation result corresponding to one waveform; Obtain the absolute values corresponding to the first type of advance correlation result, the first type of current correlation result, and the first type of delayed correlation result corresponding to the first type of waveform, and use the largest absolute value as the corresponding value of the first type of waveform. The first relevant result; Multiply and accumulate the waveform data without delay, the waveform data delayed by one sampling point, and the waveform data delayed by two sampling points with the sample point value of the second type of waveform, respectively, to obtain the first The second type of advance correlation result, the second type of current correlation result, and the second type of delayed correlation result corresponding to the two waveforms; Acquire the absolute values corresponding to the second type of advance correlation result, the second type of current correlation result, and the second type of delayed correlation result corresponding to the second type of waveform, and use the largest absolute value as the corresponding value of the second type of waveform. The second related result. 8. The decoding method for an RFID reader-writer according to claim 7, wherein after determining the decoding result corresponding to the data to be decoded in the correlation period corresponding to the actual oversampling number, The method also includes: Compare the absolute value corresponding to the first type of lead correlation result corresponding to the first type of waveform with the absolute value corresponding to the second type of lead correlation result corresponding to the second type of waveform, and use the largest absolute value as the lead correlation result. absolute value; Compare the absolute value corresponding to the first current correlation result corresponding to the first waveform with the absolute value corresponding to the second current correlation result corresponding to the second waveform, and use the largest absolute value as the current correlation result absolute value; Compare the absolute value corresponding to the first type of delayed correlation result corresponding to the first type of waveform with the absolute value corresponding to the second type of delayed correlation result corresponding to the second type of waveform, and use the largest absolute value as the delayed correlation result. The absolute value of the post-correlation result; Determine the read address flag according to the maximum value among the absolute value of the leading correlation result, the absolute value of the current correlation result and the absolute value of the delayed correlation result; Obtain the actual starting point of the data to be decoded for the next relevant cycle according to any of the following formulas: A _n =A _o +2-flag, or An =A _{o +} 3-2*flag, Wherein, An _is the actual starting point, A _o is the end point of the current correlation cycle, and flag is the read address flag. When the absolute value of the lead correlation result is the largest, the flag value is 0. When the absolute value of the correlation result is the largest, the flag value is 1, and when the absolute value of the delayed correlation result is the largest, the flag value is 2; The data to be decoded in the next relevant cycle is extracted from the actual starting point to perform a decoding operation. 9. A decoding device for an RFID reader, characterized in that the device comprises: a receiving unit for receiving the return signal of the electronic tag; a signal sampling unit, configured to obtain an in-phase signal and a quadrature signal from the return signal at a preset sampling frequency, where the preset sampling frequency is a preset multiple of the return frequency of the return signal; a phase calculation unit, configured to obtain a complex signal corresponding to the return signal according to the data phase of the in-phase signal and the quadrature signal; A data-to-be-decoded determination unit, configured to determine the data to be decoded and the single pilot tone in the complex signal according to the return frequency, the preset sampling frequency, the frequency preset deviation range and the encoding type of the return signal The actual number of oversampling; A decoding unit, configured to determine a decoding result corresponding to the data to be decoded in the correlation period corresponding to the actual oversampling number according to the encoding type of the returned signal and the actual oversampling number. 10 . The decoding device for an RFID reader according to claim 9 , wherein the signal sampling unit is further configured to sample the in-phase signal in the return signal by sampling through an analog-to-digital converter ADC. 11 . The in-phase signal and the quadrature signal in the digital domain are respectively filtered at the preset sampling frequency. 11. The decoding device for an RFID reader according to claim 9, wherein the phase calculation unit is further configured to, according to F=(I+j*Q)*e ^(-j*Φ) , obtain the complex signal F corresponding to the return signal, where I is the in-phase signal, Q is the quadrature signal, and Φ is the calculated value of the channel phase, where Φ≈atan(Q/I). 12 . The decoding device for an RFID reader according to claim 9 , wherein the device further comprises: a threshold comparison unit, configured to compare the real part of the complex signal with a preset signal threshold. 13 . ; When the real part of the complex signal is lower than the preset signal threshold, determine that the return signal of the electronic label is an invalid signal, and end the decoding operation of the return signal; when the real part of the complex signal is not low At the preset signal threshold, it is determined that the return signal of the electronic tag is a valid signal, and the decoding operation of the return signal is continued. 13. The decoding device for an RFID reader according to claim 9, wherein the data to be decoded determining unit is also used for, according to H _l =F _S /[F ₀ *(1+r) ], H _h =F _S /[F ₀ *(1-r)], obtain the lower limit H _l and upper limit H _h of the oversampling number of the single pilot tone in the complex signal, where F ₀ is the return frequency, F _S is the preset sampling frequency, and ±r% is the preset deviation range of the frequency; according to the lower limit value and the upper limit value of the oversampling number, the complex signal is obtained. The value range of the oversampling number of the single pilot tone; according to the value range of the oversampling number and the encoding type of the returned signal, determine each oversampling number in the value range of the oversampling number The corresponding preamble capture coefficient; the preamble capture coefficient corresponding to each oversampling number is used as the coefficient of the preamble matched filter corresponding to each oversampling number; the real part of the complex signal corresponds to each oversampling number The preamble matched filter is matched, and the matching output value corresponding to each oversampling number is obtained; the oversampling number corresponding to the maximum value in the matching output value is used as the actual oversampling of the single pilot tone in the complex signal. The number of samples; according to the encoding protocol corresponding to the encoding type, determine the preamble corresponding to the actual oversampling number, and use the data after removing the preamble in the complex signal as the data to be decoded. 14. The decoding device for an RFID reader according to claim 9, wherein the decoding unit is further configured to determine the the sample point values of the first waveform and the second waveform in the relevant period; from the data to be decoded, extract the waveform data in the relevant period; respectively and the first waveform The sample point value and the sample point value of the second waveform are multiplied and accumulated to obtain a first correlation result corresponding to the first waveform and a second correlation result corresponding to the second waveform respectively. ; The maximum value in the first correlation result and the second correlation result is used as the signal decision result; The waveform corresponding to the signal decision result is determined as the corresponding waveform of the data to be decoded in the correlation period decoding result. 15 . The decoding device for an RFID reader according to claim 14 , wherein the decoding unit is further configured to convert the waveform data without delay, the waveform data delayed by one sampling point, The waveform data delayed by two sample points is respectively multiplied and accumulated with the sample point value of the first waveform, to obtain the first type of advance correlation result, the first type of current correlation result, the corresponding to the first type of waveform, respectively. The first type of delayed correlation result; obtain the first type of advance correlation result corresponding to the first type of waveform, the first type of current correlation result, and the absolute value corresponding to the first type of delayed correlation result, and use the largest absolute value as The first type of correlation result corresponding to the first type of waveform; the waveform data without delay, the waveform data delayed by one sampling point, and the waveform data delayed by two sampling points are respectively correlated with the second type of waveform Multiply and accumulate the sample values of The absolute value corresponding to the second type of advance correlation result, the second type of current correlation result, and the second type of delayed correlation result, and the largest absolute value is used as the second type of correlation result corresponding to the second type of waveform. 16 . The decoding device for an RFID reader according to claim 15 , wherein the device further comprises: a starting point calibration unit, configured to correlate the first type of waveform corresponding to the first type of waveform in advance. 17 . The absolute value corresponding to the result is compared with the absolute value corresponding to the second type of advance correlation result corresponding to the second type of waveform, and the largest absolute value is used as the absolute value of the advance correlation result; The absolute value corresponding to the current correlation result is compared with the absolute value corresponding to the second current correlation result corresponding to the second waveform, and the maximum absolute value is used as the absolute value of the current correlation result; the first waveform corresponding to The absolute value corresponding to the first type of delayed correlation result is compared with the absolute value corresponding to the second type of delayed correlation result corresponding to the second waveform, and the largest absolute value is used as the absolute value of the delayed correlation result; The maximum value among the absolute value of the preceding correlation result, the absolute value of the current correlation result and the absolute value of the delayed correlation result is determined, and the read address flag is determined; Starting point: An =A _{o +} 2-flag, or An =A _{o +} 3-2*flag, _where An is the actual starting point, A _o is the end point of the current correlation cycle, and flag is the Read the address flag, when the absolute value of the advanced correlation result is the largest, the flag value is 0, when the absolute value of the current correlation result is the largest, the flag value is 1, when the absolute value of the delayed correlation result is the largest, The value of flag is 2; the data to be decoded in the next relevant cycle is extracted from the actual starting point to perform a decoding operation. 17. An RFID reader/writer, characterized in that, the RFID reader/writer comprises: the decoding device for an RFID reader/writer according to any one of claims 9-16. 18. A machine-readable storage medium storing instructions on the machine-readable storage medium for causing a machine to execute the decoding method for an RFID reader/writer according to any one of claims 1-8.

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