CN115102582B

CN115102582B - Decoding method and device for RFID reader-writer, storage medium and RFID reader-writer

Info

Publication number: CN115102582B
Application number: CN202211016590.8A
Authority: CN
Inventors: 陈家国; 张喆; 马岩; 赵东艳; 张晓燚; 刘福华; 王昊
Original assignee: Beijing Smartchip Microelectronics Technology Co Ltd
Current assignee: Beijing Smartchip Microelectronics Technology Co Ltd
Priority date: 2022-08-24
Filing date: 2022-08-24
Publication date: 2023-01-24
Anticipated expiration: 2042-08-24
Also published as: CN115102582A; WO2024040650A1

Abstract

The invention relates to the technical field of radio frequency identification, and discloses a decoding method and device for an RFID reader-writer, a storage medium and the RFID reader-writer, wherein the decoding method comprises the following steps: preprocessing the received label signal to obtain a complex signal corresponding to the label signal; carrying out signal frequency estimation on the complex signal to obtain a signal frequency indicated value; determining a lead code acquisition coefficient according to the signal frequency indicating value; acquiring a lead code in the complex signal according to the lead code acquisition coefficient; and determining data to be decoded in the complex signal based on the preamble, and decoding the data to be decoded. Therefore, the frequency estimation and the lead code capture are divided into two stages, so that the overall computing resource consumption can be greatly reduced, the lead code capture reliability is improved, the decoding success rate of the data to be decoded is improved, and the requirement on the signal to noise ratio is low.

Description

Decoding method and device for RFID reader-writer, storage medium and RFID reader-writer

Technical Field

The invention relates to the technical field of radio frequency identification, in particular to a decoding method and device for an RFID reader-writer, a storage medium and the RFID reader-writer.

Background

The Radio Frequency Identification (RFID) technology is a wireless communication technology widely used in logistics, asset management, and article anti-counterfeiting. Signal demodulation technology is a core technology in RFID technology.

In the related art, most signal demodulation schemes require a high signal-to-noise ratio to avoid error codes during signal demodulation, and when the distance between a reader and a tag is too far (for example, more than 10 meters) or a signal returned by the tag is weak (for example, weaker than-80 dBm), decoding difficulty is easy to occur, so that the decoding success rate is greatly reduced.

There are also a small number of signal demodulation schemes that can improve the decoding success rate at low signal-to-noise ratios. For example, according to the return frequency, the preset sampling frequency, the preset frequency deviation range and the coding type of the return signal, the data to be decoded and the actual oversampling number in the return signal are obtained through the matched filter, and then the corresponding decoding result is obtained, but the first-stage parallel matched filter is adopted for preamble capture and frequency estimation in the method, the consumption of computing resources is large, and particularly, the computing resources are multiplied when the coding type is miller4, miller8 or miller16 and the like.

Disclosure of Invention

The present invention is directed to solving, at least in part, one of the technical problems in the related art. Therefore, a first objective of the present invention is to provide a decoding method for an RFID reader, in which frequency estimation and preamble capture are divided into two stages, the first stage is used for obtaining a signal frequency indication value by signal frequency estimation of a complex signal, and determining a preamble capture coefficient based on the signal frequency indication value, and the second stage is used for capturing a preamble based on the preamble capture coefficient, so as to achieve decoding of data to be decoded based on the captured preamble, thereby greatly reducing overall computing resource consumption, and simultaneously improving reliability of preamble capture, and further improving decoding success rate of the data to be decoded, and having low requirement on signal-to-noise ratio.

A second object of the invention is to propose a computer-readable storage medium.

The third purpose of the invention is to provide an RFID reader-writer.

A fourth object of the present invention is to provide a decoding device for an RFID reader.

In order to achieve the above object, an embodiment of a first aspect of the present invention provides a decoding method for an RFID reader, where the method includes: preprocessing the received label signal to obtain a complex signal corresponding to the label signal; carrying out signal frequency estimation on the complex signal to obtain a signal frequency indicated value; determining a lead code acquisition coefficient according to the signal frequency indicating value; capturing a lead code in the complex signal according to the lead code capturing coefficient; and determining data to be decoded in the complex signal based on the preamble, and decoding the data to be decoded.

According to the decoding method for the RFID reader-writer, the received tag signals are preprocessed to obtain the complex signals corresponding to the tag signals, then the complex signals are subjected to signal frequency estimation to obtain the signal frequency indicated values, the lead code capturing coefficients are determined according to the signal frequency indicated values, the lead codes in the complex signals are captured according to the lead code capturing coefficients, finally the data to be decoded in the complex signals are determined based on the lead codes, and the data to be decoded are decoded. Therefore, the frequency estimation and the lead code capture are divided into two stages, the first stage is used for obtaining a signal frequency indicated value through the signal frequency estimation of the complex signal and determining a lead code capture coefficient based on the signal frequency indicated value, the second stage is used for capturing the lead code based on the lead code capture coefficient and then decoding the data to be decoded is realized based on the captured lead code, the overall computing resource consumption can be greatly reduced, meanwhile, the reliability of the lead code capture is improved, the decoding success rate of the data to be decoded is improved, and the requirement on the signal to noise ratio is low.

According to an embodiment of the present invention, preprocessing the received tag signal to obtain a complex signal corresponding to the tag signal includes: sampling according to a preset sampling rate to obtain an in-phase signal and an orthogonal signal in a label signal; filtering the in-phase signal and the orthogonal signal; and carrying out phase rotation processing on the in-phase signal and the orthogonal signal after filtering processing to obtain a complex signal.

According to an embodiment of the present invention, the filtering process includes at least one of a low-frequency noise filtering process, a direct-current signal filtering process, and a high-frequency signal filtering process.

According to an embodiment of the present invention, performing signal frequency estimation on a complex signal to obtain a signal frequency indication value includes: determining an oversampling number range corresponding to a pilot tone in the complex signal according to a signal frequency value of the complex signal, a preset frequency deviation range and a preset sampling rate; determining the coefficient of a signal frequency matching filter corresponding to each oversampling number in the oversampling number range; matching the complex signal with a signal frequency matching filter corresponding to each oversampling number to obtain a matching output value corresponding to each oversampling number; and taking the oversampling number corresponding to the maximum value in the matching output values as a signal frequency indication value.

According to one embodiment of the invention, the pilot tone is a single pilot tone or multiple pilot tones.

According to one embodiment of the present invention, determining a preamble acquisition coefficient according to a signal frequency indication value includes: determining an inverted waveform of the lead code according to the coding type and the standard of the complex signal; and determining a preamble acquisition coefficient according to the signal frequency indication value and the inverted waveform of the preamble.

According to an embodiment of the present invention, the preamble acquisition coefficients include three preamble acquisition coefficients, which are respectively a value obtained by subtracting 1 from the signal frequency indication value, a preamble acquisition coefficient corresponding to the signal frequency indication value, and a value obtained by adding 1 to the signal frequency indication value.

According to one embodiment of the invention, acquiring the preamble in the complex signal according to the preamble acquisition coefficient comprises the following steps: taking the three preamble capture coefficients as coefficients of three preamble matched filters; matching the complex signal with each lead code matched filter to obtain a matched output value corresponding to each lead code matched filter; and taking the peak time output by the preamble matched filter corresponding to the maximum value in the matched output values as the end time of the preamble.

According to an embodiment of the invention, the method further comprises: and determining the sampling number corresponding to the code pattern in the data to be decoded according to the lead code matched filter corresponding to the maximum value in the matched output values and the signal frequency indicated value.

According to an embodiment of the present invention, determining the number of samples corresponding to the code pattern in the data to be decoded according to the preamble matched filter corresponding to the maximum value in the matched output value and the signal frequency indication value includes: determining a lead code matched filter corresponding to the maximum value in the matched output values as a lead code matched filter corresponding to a value obtained by subtracting 1 from the signal frequency indicated value, wherein the sampling number is a value obtained by subtracting 1 from K times of the signal frequency indicated value; determining a lead code matched filter corresponding to the maximum value in the matched output values as a lead code matched filter corresponding to the signal frequency indicated value, wherein the sampling number is K times of the signal frequency indicated value; and determining the lead code matched filter corresponding to the maximum value in the matched output values as the lead code matched filter corresponding to the value obtained by adding 1 to the signal frequency indicated value, wherein the sampling number is the value obtained by adding 1 to the K times of the signal frequency indicated value.

According to one embodiment of the present invention, determining data to be decoded in a complex signal based on a preamble, and decoding the data to be decoded includes: and decoding the data to be decoded according to the sampling number corresponding to the code pattern and each code pattern in the complex signal from the ending time of the preamble code.

According to an embodiment of the invention, the method further comprises: determining whether a complex signal exists according to the signal frequency indication value; if the complex signal is determined to exist, acquiring a lead code; determining that a complex signal is not present, stopping acquisition of the preamble.

In order to achieve the above object, a second aspect of the present invention provides a computer-readable storage medium, on which a decoding program for an RFID reader is stored, which when executed by a processor implements the foregoing decoding method for the RFID reader.

According to the computer-readable storage medium provided by the embodiment of the invention, by adopting the decoding method for the RFID reader, frequency estimation and lead code capture are divided into two stages, the first stage is used for obtaining a signal frequency indicated value through signal frequency estimation of a complex signal, a lead code capture coefficient is determined based on the signal frequency indicated value, the second stage is used for capturing the lead code based on the lead code capture coefficient, and then decoding of data to be decoded is realized based on the captured lead code, so that the whole computing resource consumption can be greatly reduced, the reliability of lead code capture is improved, the decoding success rate of the data to be decoded is improved, and the requirement on the signal to noise ratio is lower.

In order to achieve the above object, an embodiment of a third aspect of the present invention provides an RFID reader, including: the RFID reader-writer decoding method comprises a memory, a processor and a decoding program which is stored on the memory and can be run on the processor, wherein when the processor executes the program, the decoding method for the RFID reader-writer is realized.

According to the RFID reader-writer provided by the embodiment of the invention, by adopting the decoding method for the RFID reader-writer, the frequency estimation and the lead code capture are divided into two stages, the first stage is used for obtaining the signal frequency indicated value by the signal frequency estimation of the complex signal, and determining the lead code capture coefficient based on the signal frequency indicated value, the second stage is used for capturing the lead code based on the lead code capture coefficient, so that the decoding of the data to be decoded is realized based on the captured lead code, the whole computing resource consumption can be greatly reduced, the reliability of the lead code capture is improved, the decoding success rate of the data to be decoded is improved, and the requirement on the signal-to-noise ratio is lower.

In order to achieve the above object, a fourth aspect of the present invention provides a decoding apparatus for an RFID reader, the apparatus including: the preprocessing module is used for preprocessing the received label signal to obtain a complex signal corresponding to the label signal; the frequency estimation module is used for carrying out signal frequency estimation on the complex signal to obtain a signal frequency indicated value; the lead code acquisition module is used for determining a lead code acquisition coefficient according to the signal frequency indication value and acquiring a lead code in the complex signal according to the lead code acquisition coefficient; and the decoding module is used for determining data to be decoded in the complex signal based on the lead code and decoding the data to be decoded.

According to the decoding device for the RFID reader-writer provided by the embodiment of the invention, the received tag signal is preprocessed by the preprocessing module to obtain the complex signal corresponding to the tag signal, the frequency estimation module is used for carrying out signal frequency estimation on the complex signal to obtain the signal frequency indicated value, the lead code capturing module is used for determining the lead code capturing coefficient according to the signal frequency indicated value and capturing the lead code in the complex signal according to the lead code capturing coefficient, and finally, the decoding module is used for determining the data to be decoded in the complex signal based on the lead code and decoding the data to be decoded. Therefore, the frequency estimation and the lead code capture are divided into two stages, the first stage is used for obtaining a signal frequency indicated value through the signal frequency estimation of the complex signal and determining a lead code capture coefficient based on the signal frequency indicated value, the second stage is used for capturing the lead code based on the lead code capture coefficient and then decoding the data to be decoded is realized based on the captured lead code, the overall computing resource consumption can be greatly reduced, meanwhile, the reliability of the lead code capture is improved, the decoding success rate of the data to be decoded is improved, and the requirement on the signal to noise ratio is low.

According to one embodiment of the invention, the pre-processing module comprises: the sampling unit is used for sampling according to a preset sampling rate to obtain an in-phase signal and an orthogonal signal in the label signal; the filtering unit is used for filtering the in-phase signal and the orthogonal signal; and the processing unit is used for carrying out phase rotation processing on the in-phase signal and the orthogonal signal after filtering processing to obtain a complex signal.

According to an embodiment of the present invention, the frequency estimation module is specifically configured to: determining an oversampling number range corresponding to a pilot tone in the complex signal according to a signal frequency value of the complex signal, a preset frequency deviation range and a preset sampling rate; determining the coefficient of a signal frequency matching filter corresponding to each oversampling number in the oversampling number range; matching the complex signal with a signal frequency matching filter corresponding to each oversampling number to obtain a matching output value corresponding to each oversampling number; and taking the oversampling number corresponding to the maximum value in the matching output values as a signal frequency indication value.

According to an embodiment of the present invention, the preamble acquisition module is specifically configured to: determining an inverted waveform of the lead code according to the coding type and the standard of the complex signal; and determining a preamble acquisition coefficient according to the signal frequency indication value and the inverted waveform of the preamble.

According to an embodiment of the present invention, the preamble acquisition coefficients include three preamble acquisition coefficients, which are respectively a value obtained by subtracting 1 from the signal frequency indication value, a preamble acquisition coefficient corresponding to the signal frequency indication value, and a preamble acquisition coefficient corresponding to a value obtained by adding 1 to the signal frequency indication value.

According to an embodiment of the present invention, the preamble acquisition module is specifically configured to: taking the three preamble capture coefficients as coefficients of three preamble matched filters; matching the complex signal with each lead code matched filter to obtain a matched output value corresponding to each lead code matched filter; and taking the peak time output by the preamble matched filter corresponding to the maximum value in the matched output values as the end time of the preamble.

According to an embodiment of the present invention, the preamble acquisition module is further configured to: and determining the sampling number corresponding to the code pattern in the data to be decoded according to the lead code matched filter corresponding to the maximum value in the matched output values and the signal frequency indicated value.

According to one embodiment of the invention, the lead code matched filter corresponding to the maximum value in the matching output values is determined to be the lead code matched filter corresponding to the value obtained by subtracting 1 from the signal frequency indicated value, the sampling number is the value obtained by subtracting 1 from the K times of the signal frequency indicated value, wherein K is an integer, and K is determined according to the coding type of the complex signal; determining a lead code matched filter corresponding to the maximum value in the matched output values as a lead code matched filter corresponding to the signal frequency indicated value, wherein the sampling number is K times of the signal frequency indicated value; and determining the lead code matched filter corresponding to the maximum value in the matched output values as the lead code matched filter corresponding to the value obtained by adding 1 to the signal frequency indicated value, wherein the sampling number is the value obtained by adding 1 to the K times of the signal frequency indicated value.

According to an embodiment of the present invention, the decoding module is specifically configured to: and decoding the data to be decoded according to the sampling number corresponding to the code pattern and each code pattern in the complex signal from the ending time of the preamble code.

According to an embodiment of the invention, the apparatus further comprises a signal detection module for: determining whether a complex signal exists according to the signal frequency indication value; if the complex signal is determined to exist, controlling a lead code acquisition module to acquire a lead code; and controlling the preamble acquisition module to stop acquiring the preamble if the complex signal is determined not to exist.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

Fig. 1 is a flowchart of a decoding method for an RFID reader according to an embodiment of the present invention;

FIG. 2 is a flow chart of complex signal acquisition according to one embodiment of the present invention;

FIG. 3 is a flow chart of signal frequency indication value acquisition according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of a structure for signal frequency estimation according to an embodiment of the present invention;

fig. 5 is a flowchart of preamble capture coefficient acquisition according to an embodiment of the present invention;

fig. 6 is a waveform diagram of a preamble according to an embodiment of the present invention;

fig. 7 is a flow diagram of preamble acquisition according to one embodiment of the invention;

fig. 8 is a schematic structural diagram for preamble acquisition according to an embodiment of the present invention;

FIG. 9 is a schematic diagram of an RFID reader/writer according to an embodiment of the present invention;

fig. 10 is a schematic structural diagram of a decoding device for an RFID reader according to an embodiment of the present invention;

fig. 11 is a schematic structural diagram of a decoding device for an RFID reader according to another embodiment of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

The following describes a decoding method, apparatus, storage medium, and RFID reader for an RFID reader according to an embodiment of the present invention with reference to the drawings.

Fig. 1 is a flowchart of a decoding method for an RFID reader according to an embodiment of the present invention, and referring to fig. 1, the decoding method for an RFID reader may include:

step S110, preprocessing the received tag signal to obtain a complex signal corresponding to the tag signal.

Specifically, after the RFID reader sends a radio frequency signal to the electronic tag, the electronic tag returns a tag signal to the RFID reader. When the electronic tag is a passive electronic tag, the passive electronic tag supplies power to the passive electronic tag for a short time by acquiring the energy of a radio frequency signal sent by the RFID reader-writer so as to return a tag signal to the RFID reader-writer.

After receiving the tag signal of the electronic tag, the RFID reader can perform analog-to-digital conversion on the tag signal to obtain a digital signal, and perform processing such as sampling, filtering, phase rotation and the like on the digital signal to obtain a complex signal. The energy of the label signal can be concentrated on the real part of the complex signal through phase rotation, so that the signal-to-noise ratio can be improved, processing resources can be saved, and the problem of rapid strong signal conversion caused by relative movement of the RFID reader and the electronic label can be solved.

Step S120, performing signal frequency estimation on the complex signal to obtain a signal frequency indication value.

It should be noted that the signal frequency indication value is a value indicating a signal frequency estimation value of the complex signal, and is in one-to-one correspondence with the signal frequency estimation value, for example, the signal frequency indication value is an actual oversampling number, and specifically may be an actual oversampling number corresponding to a pilot tone in the complex signal, and the signal frequency estimation value may be calculated based on the actual oversampling number.

After obtaining the complex signal, the RFID reader may perform signal frequency estimation on the complex signal to obtain a signal frequency indication value, for example, may perform matched filtering on a real part of the complex signal based on a matched filter to obtain an actual oversampling number of a pilot tone in the complex signal, and use the actual oversampling number as the signal frequency indication value of the complex signal.

Step S130, determining a preamble acquisition coefficient according to the signal frequency indication value.

It should be noted that determining that the data to be decoded in the complex signal is actually capturing the preamble in the complex signal, and removing the preamble is the data to be decoded. When the preamble is captured, it is necessary to determine a preamble capture coefficient corresponding to the captured preamble, and when the preamble is captured based on the matched filter, the preamble capture coefficient specifically refers to a coefficient of the matched filter.

When the preamble acquisition coefficient is obtained, the preamble acquisition coefficient may be determined according to the signal frequency indication value and the coding type and standard of the complex signal, for example, different standards, different coding types, and different signal frequency indication values correspond to different preamble acquisition coefficients.

And step S140, capturing the lead code in the complex signal according to the lead code capturing coefficient.

In particular, after obtaining the preamble acquisition coefficients, the preambles in the complex signal may be acquired based on the preamble coefficients. For example, when performing preamble capture based on a matched filter, coefficients of the matched filter may be set based on the preamble capture coefficients, and then the matched filter performs matched filtering on a real part of the complex signal to obtain a preamble in the complex signal.

And S150, determining data to be decoded in the complex signal based on the lead code, and decoding the data to be decoded.

It should be noted that the data after the end time of the preamble is the data to be decoded, so that after the preamble is obtained, the end time of the preamble can be determined, and then the data to be decoded can be determined.

In the embodiment, the frequency estimation and the lead code capture are divided into two stages, the first stage is used for obtaining the signal frequency indicated value through the signal frequency estimation of the complex signal, the lead code capture coefficient is determined based on the signal frequency indicated value, the second stage is used for capturing the lead code based on the lead code capture coefficient, and then the decoding of the data to be decoded is realized based on the captured lead code, so that the overall computing resource consumption can be greatly reduced, meanwhile, the lead code capture reliability is improved, the decoding success rate of the data to be decoded is improved, and the requirement on the signal to noise ratio is low.

In some embodiments, referring to fig. 2, the preprocessing the received tag signal in step S110 to obtain a complex signal corresponding to the tag signal may include:

and step S111, sampling according to a preset sampling rate to obtain an in-phase signal and a quadrature signal in the label signal.

It should be noted that the tag signal is generally an analog signal in a continuous time domain, and after the tag signal is received, the in-phase signal and the quadrature signal in the tag signal may be respectively sampled by the analog-to-digital converter at a preset sampling rate, so as to convert the in-phase signal and the quadrature signal in the tag signal into digital signals. The preset sampling rate is generally a preset multiple of the signal frequency value of the tag signal, that is, a preset multiple of the signal frequency value of the complex signal, for example, the preset multiple is an integer greater than or equal to 16, and the preset sampling rate may be specifically set according to an actual situation, which is not limited herein, so that the actual signal frequency value of the tag signal, that is, the signal frequency indication value of the complex signal, can be accurately obtained in the following.

In step S112, the in-phase signal and the quadrature signal are subjected to filter processing.

The filtering process is mainly used to filter out unwanted signals, interference signals, and the like. Optionally, the filtering process includes at least one of a low-frequency noise filtering process, a direct-current signal filtering process, and a high-frequency signal filtering process, for example, the in-phase signal and the quadrature signal of the tag signal obtained by sampling may be respectively filtered according to the interference condition of the tag signal and the frequency band in which the tag signal is located, so as to filter out the low-frequency noise, the direct-current component, the high-frequency component, and the like in the signal.

Step S113, performs phase rotation processing on the filtered in-phase signal and quadrature signal to obtain a complex signal.

Specifically, the following may be based on the formula: and F = (I + j × Q) × exp (-j × Φ) to calculate a complex signal corresponding to the tag signal, wherein F is the complex signal corresponding to the tag signal, I is an in-phase signal, Q is an orthogonal signal, Φ is a calculated value of a channel phase, and Φ ≈ atan (Q/I). The label signal is subjected to phase calculation and rotation through the formula, most signal energy in the label signal can be concentrated in the real part of the complex signal, the imaginary part only has a small amount of signals, and the signal of the imaginary part can be ignored in subsequent processing, namely, only the real part of the complex signal is processed, so that the signal-to-noise ratio can be improved, processing resources can be saved, and the problem of rapid strong signal conversion caused by relative movement of an RFID reader-writer and an electronic label can be solved.

In the above embodiment, the in-phase signal and the quadrature signal in the tag signal are sampled, filtered and phase-rotated, so that the tag signal is preprocessed and converted into the complex signal with most energy concentrated on the real part, and thus, not only can processor resources be saved, but also the decoding capability of the tag signal under the condition of low signal-to-noise ratio can be improved.

In some embodiments, referring to fig. 3, the performing signal frequency estimation on the complex signal in step S120 to obtain a signal frequency indication value includes:

step S121, determining an oversampling number range corresponding to a pilot tone in the complex signal according to the signal frequency value of the complex signal, the preset frequency deviation range, and the preset sampling rate.

It should be noted that the signal frequency value of the complex signal, that is, the signal frequency value of the tag signal, is predetermined, and the preset frequency deviation range and the preset sampling rate are also predetermined.

Specifically, the following may be based on the formula: hl = FS/[ F0 (1+r) ] and Hh = FS/[ F0 (1-r) ] determine an oversampling number range corresponding to the pilot tone in the complex signal, where Hl is a lower limit of the oversampling number range, hh is an upper limit of the oversampling number range, FS is a preset sampling rate, F0 is a signal frequency value of the tag signal, that is, a signal frequency value of the complex signal, and r is a preset frequency deviation range, which can be specifically determined based on a coding protocol of the tag signal. It should be noted that there may be some decimal in the calculation results when calculating Hl and Hh, and the calculation results may be rounded based on a rounding method to obtain the oversampled number range [ Hl, hh ].

For example, taking the signal frequency value BLF of the tag signal as 320kHz, the preset sampling rate as 6400k samples per second, and the preset frequency deviation range determined based on the encoding protocol of the tag signal as ± 22%, the oversampling number range corresponding to the pilot tone in the complex signal is calculated as [ 6400/(320 × 1.22), 6400/(320 × 0.78) ], and after the calculation result is rounded, the oversampling number range corresponding to the pilot tone is [16,26].

Step S122, determining the coefficient of the signal frequency matched filter corresponding to each oversampling number in the oversampling number range.

It should be noted that, in order to cover the preset frequency deviation range corresponding to the tag signal, hh-Hl +1 signal frequency matching filters are required to perform signal frequency estimation, for example, when the calculated oversampling number range is [16,26], 11 parallel signal frequency matching filters are used to perform signal frequency estimation, and each signal frequency matching filter corresponds to one oversampling number, and the coefficient of each signal frequency matching filter can be determined by the oversampling number and the transmission protocol corresponding to the tag signal.

For example, as a first example, taking a pilot tone as a single pilot tone, when the oversampling number range of the determined pilot tone is [16,26], the coefficients of each signal frequency matching filter may be:

coefficient of the signal frequency matched filter with oversampling number of 16: 000011111111;

coefficient of the signal frequency matching filter with oversampling number of 17: 00000000111111111;

coefficient of the signal frequency matching filter with oversampling number of 18: 000000000111111111;

coefficient of the signal frequency matching filter with oversampling number of 19: 0000000001111111111;

coefficient of the signal frequency matching filter for oversampling number 20: 00000000001111111111;

coefficient of the signal frequency matching filter for oversampling number 21: 000000000011111111111;

the oversampling number is 22 corresponding to the coefficients of the signal frequency matching filter: 0000000000011111111111;

coefficient of the signal frequency matching filter for 23 oversampling numbers: 00000000000111111111111;

the oversampling number is 24 coefficients of the signal frequency matching filter: 000000000000111111111111;

coefficient of the signal frequency matching filter with oversampling number of 25: 0000000000001111111111111;

coefficient of the signal frequency matching filter with oversampling number of 26: 00000000000001111111111111.

as a second example, taking the pilot tone as a multi-pilot tone, such as a dual pilot tone, when the oversampling number of the determined pilot tone is in the range of [16,26], the coefficients of the respective signal frequency matching filters may be:

coefficient of the signal frequency matching filter with oversampling number of 16:

0000000011111111_0000000011111111；

coefficient of the signal frequency matching filter with oversampling number of 17:

00000000111111111_00000000111111111；

coefficient of the signal frequency matching filter with oversampling number of 18:

000000000111111111_000000000111111111；

coefficient of the signal frequency matching filter with oversampling number of 19:

0000000001111111111_0000000001111111111；

coefficient of the signal frequency matching filter for oversampling number 20:

00000000001111111111_00000000001111111111；

coefficient of the signal frequency matching filter for oversampling number 21:

000000000011111111111_000000000011111111111；

the oversampling number is 22 corresponding to the coefficients of the signal frequency matching filter:

0000000000011111111111_0000000000011111111111；

coefficient of the signal frequency matching filter for 23 oversampling numbers:

00000000000111111111111_00000000000111111111111；

the oversampling number is 24 coefficients of the signal frequency matching filter:

000000000000111111111111_000000000000111111111111；

coefficient of the signal frequency matching filter with oversampling number of 25:

0000000000001111111111111_0000000000001111111111111；

coefficient of the signal frequency matching filter with oversampling number of 26:

00000000000001111111111111_00000000000001111111111111。

as a third example, taking the pilot tone as a multi-pilot tone, such as a triple pilot tone, when the oversampling number range of the determined pilot tone is [16,26], the coefficients of the respective signal frequency matching filters may be:

0000000011111111_0000000011111111_0000000011111111；

00000000111111111_00000000111111111_00000000111111111；

000000000111111111_000000000111111111_000000000111111111；

0000000001111111111_0000000001111111111_0000000001111111111；

coefficient of the signal frequency matching filter for oversampling number 20:

00000000001111111111_00000000001111111111_00000000001111111111；

coefficient of the signal frequency matching filter for oversampling number 21:

000000000011111111111_000000000011111111111_000000000011111111111；

0000000000011111111111_0000000000011111111111_0000000000011111111111；

00000000000111111111111_00000000000111111111111_00000000000111111111111；

000000000000111111111111_000000000000111111111111_000000000000111111111111；

0000000000001111111111111_0000000000001111111111111_0000000000001111111111111；

00000000000001111111111111_00000000000001111111111111_00000000000001111111111111。

it should be noted that whether the pilot tone is a single pilot tone or multiple pilot tones may be determined by a transmission protocol corresponding to the tag signal, where the greater the number of pilot tones, the stronger the anti-interference capability of the tag signal is, and the more stable the transmission of the tag signal is.

And step S123, matching the complex signal with a signal frequency matching filter corresponding to each oversampling number to obtain a matching output value corresponding to each oversampling number.

Specifically, referring to fig. 4, the real part of the complex signal may be input to m (i.e., hh-Hl + 1) signal frequency matching filters in parallel for signal frequency matching, and detected by a matching output detector, so as to obtain a matching output value corresponding to each oversampling number, and input to a maximum matching output detector.

In step S124, the oversampling number corresponding to the maximum value of the matching output values is set as the signal frequency indication value.

Specifically, as shown in fig. 4, the maximum matching output detector compares the matching output values corresponding to the respective oversampling numbers to obtain a maximum value of the matching output values, and uses the oversampling number corresponding to the maximum value as the signal frequency indication value. For example, if the maximum value corresponds to an oversampling number of 22, the complex signal has a signal frequency indicating value of 22. It should be noted that the signal frequency indication value corresponds to the signal frequency estimation value one to one, and after the signal frequency indication value is obtained, the signal frequency estimation value of the complex signal, that is, the actual signal frequency value, can be calculated based on the preset sampling rate and the signal frequency indication value.

In the above embodiment, the signal frequency indication value of the complex signal is obtained based on the first-stage matched filtering according to the signal frequency value of the complex signal, the preset frequency deviation range, the preset sampling rate, and the like.

In some embodiments, referring to fig. 5, the determining the preamble acquisition coefficient according to the signal frequency indicator value in step S130 may include:

step S131, determining the inverted waveform of the lead code according to the coding type and standard of the complex signal.

It should be noted that the encoding type and standard of the complex signal, that is, the encoding type and standard of the tag signal, for example, the encoding type of the tag signal may be an FM0 encoding type, a MILLER encoding type (such as MILLER4, MILLER8, MILLER16, etc.), etc., and the standard of the tag signal may be a 6C standard, a national military standard, etc.

In addition, due to the natural characteristic of the matched filter, in a gaussian channel, the system function of the optimal matched filter is the conjugate match of the shaping filter, and an inversion relation is presented in a time domain, so that an inverted waveform of the lead code can be obtained firstly, and then a lead code capturing coefficient is determined based on the inverted waveform of the lead code. For example, taking FM0 encoding of the 6C standard as an example, the waveform of the preamble "1010v1" is shown in fig. 6 (a), and the inverted waveform of the corresponding preamble "1010v1" is shown in fig. 6 (b).

Step S132 determines a preamble acquisition coefficient according to the signal frequency indication value and the inverted waveform of the preamble.

It should be noted that, when the signal frequency indication value is not considered, the inverted waveform of the preamble is the preamble acquisition coefficient, for example, taking the FM0 code of the 6C standard as an example, the corresponding preamble acquisition coefficient is the inverted waveform of the preamble "1010v 1"; taking the MILLER coding of the 6C standard as an example, the corresponding preamble capture coefficient is an inverted waveform that is an inversion of the waveform of the preamble "010111" after the MILLER coding.

When the signal frequency indicating value is considered, the inverted waveform may be adjusted based on the signal frequency indicating value to obtain a preamble acquisition coefficient corresponding to the signal frequency indicating value, and in order to cover an estimation error of the signal frequency indicating value, a plurality of preamble acquisition coefficients may be formed based on the signal frequency indicating value, for example, at least three preamble acquisition coefficients may be formed to perform fine adjustment on the signal frequency indicating value, improve the accuracy of preamble acquisition, and further improve the success rate of decoding.

As an example, the preamble acquisition coefficients include three preamble acquisition coefficients, which are respectively a value obtained by subtracting 1 from a signal frequency indication value, a preamble acquisition coefficient corresponding to a signal frequency indication value, and a preamble acquisition coefficient corresponding to a value obtained by adding 1 to a signal frequency indication value.

For example, assuming that the signal frequency indication value is 20, that is, a single pilot tone has 20 sampling values, in order to cover the estimation error of the signal frequency indication value, three preamble acquisition coefficients may be set, which are respectively the preamble acquisition coefficient corresponding to the signal frequency indication value 20, the preamble acquisition coefficient corresponding to the signal frequency indication value 19, and the preamble acquisition coefficient corresponding to the signal frequency indication value 21, taking the FM0 coding of the 6C standard as an example, the three finally determined preamble acquisition coefficients are:

the signal frequency indicated value is 19 corresponding preamble acquisition coefficients:

1111111111111111111_0000000000000000000_0000000001111111111_0000000000000000000_1111111111000000000_1111111111111111111；

the signal frequency indicated value is 20 corresponding to the preamble acquisition coefficient:

11111111111111111111_00000000000000000000_00000000001111111111_00000000000000000000_11111111110000000000_11111111111111111111；

preamble acquisition coefficient corresponding to signal frequency indication value 21:

111111111111111111111_000000000000000000000_000000000011111111111_000000000000000000000_111111111110000000000_111111111111111111111。

in a specific implementation, "0" in the preamble acquisition coefficient is represented by "-1", and "1" is represented by "1".

Therefore, fine adjustment of the signal frequency indicated value can be realized by setting a plurality of lead code capturing coefficients, so that the lead code capturing precision is improved, and the decoding success rate is further improved; meanwhile, due to the fine adjustment of the signal frequency indication value, the time for acquiring the preamble code is closer to the duration of the actual preamble code, so that the demodulation delay can be reduced, and the occurrence of the T2 timeout phenomenon is prevented, wherein T2 is an index specified by a signal transmission protocol, and is a time interval between the end time when the electronic tag returns the RN16 (16-bit random number) signal and the start time when the RFID reader sends an ACK (Acknowledge character) command, and T2 in the protocol is shorter.

It should be noted that, in practical applications, preamble acquisition coefficients corresponding to different standards, different coding types, and different signal frequency indication values may be stored in a rom in advance, for example, as shown in fig. 8, the rom is used to store preamble acquisition coefficients of different standards (e.g., 6C standard, military standard, national standard, etc.) and different coding types (e.g., FM0, miller2, miller4, miller8, etc.), and when determining the coding type, standard, and signal frequency indication value of the tag signal, the corresponding preamble acquisition coefficients may be read from the rom based on the index address. Therefore, the method is not only suitable for a plurality of label signals with different standards, but also has the capability of compatibly demodulating the label signals with different coding types, and meanwhile, the lead code capture coefficient is directly read from the memory, so that a large amount of computing resources can be saved.

In the above embodiment, the corresponding preamble capture coefficients can be obtained according to the signal frequency indication value and the inverted waveform of the preamble, and the number of the obtained preamble capture coefficients can be multiple, so as to finely adjust the signal frequency indication value, which is beneficial to improving the precision of preamble capture, and further beneficial to improving the success rate of decoding, and the compatibility is strong.

The acquisition of the preamble is explained below by taking the example that the preamble coefficients include three. In some embodiments, referring to fig. 7, the acquiring the preamble in the complex signal according to the preamble acquisition coefficient in step S140 may include:

in step S141, the three preamble capture coefficients are used as the coefficients of the three preamble matched filters.

Specifically, the preamble capture may be performed based on matched filters, and as shown in fig. 8, when the preamble capture coefficients are three, three parallel preamble matched filters may be used to perform the preamble capture, and the coefficients of the preamble matched filters are set according to the preamble capture coefficients, that is, the preamble capture coefficients are the coefficients of the preamble matched filters.

And step S142, matching the complex signal with each lead code matched filter to obtain a matched output value corresponding to each lead code matched filter.

Specifically, the real part of the complex signal may be input to three parallel preamble matching filters for preamble matching, and the matching output detector may perform peak detection on the output result of the preamble matching filters to obtain a matching output value corresponding to each preamble matching filter.

In step S143, the peak time output by the preamble matching filter corresponding to the maximum value of the matching output values is set as the end time of the preamble.

Specifically, the maximum matching output detector compares the matching output values corresponding to the preamble matching filters to obtain a maximum value of the matching output values, and uses a peak time output by the preamble matching filter corresponding to the maximum value as an end time of the preamble. That is to say, the real part of the complex signal is subjected to matched filtering by using the preamble capture coefficient, the amplitude peak time output by the matched filtering is the end time of the preamble, and the data after the end time is the data to be decoded. Further, the maximum matching output detector may output an address of a memory (a circular memory) corresponding to the end of the preamble, acquire data to be decoded from the memory based on the address, and decode the data to be decoded to obtain a decoding result.

In the above embodiment, the three parallel matched filters are used for capturing the preamble, so that the accuracy of preamble capture can be improved, particularly the capture capability of weak signals is improved, and further the success rate of decoding is improved, meanwhile, compared with a mode that one-stage parallel matched filters are used for preamble capture and frequency estimation, the embodiment of the invention adopts two-stage parallel matched filters to realize frequency estimation and preamble capture, wherein the frequency estimation is realized by using one-stage matched filter, and the preamble capture is realized by using another-stage matched filter, so that the probability of accurately capturing the preamble can be improved, and meanwhile, the consumption of computing resources can be greatly reduced, that is, the computing resources consumed by the parallel matched filters used for frequency estimation are determined, and the number of matched filters used for preamble capture is small, for example, only three matched filters are used on the premise of ensuring the capture reliability, the total consumption of the computing resources is greatly reduced, and particularly, the advantage of the computing resources consumed is more obvious when the coding type is miller4, miller8 or miller 16.

In some embodiments, the decoding method further comprises: and determining the sampling number corresponding to the code pattern in the data to be decoded according to the lead code matched filter corresponding to the maximum value in the matched output values and the signal frequency indicated value.

Specifically, the preamble capture takes into account the estimation error of the signal frequency indication value, so that the number of samples corresponding to the pattern in the data to be decoded is determined according to the preamble matched filter corresponding to the maximum value in the matched output value and the signal frequency indication value, and also takes into account the error of the signal frequency indication value, thereby making the finally determined number of samples more accurate.

Further, in some embodiments, determining the number of samples corresponding to the code pattern in the data to be decoded according to the preamble matched filter corresponding to the maximum value in the matched output values and the signal frequency indication value includes: determining a lead code matched filter corresponding to the maximum value in the matched output values as a lead code matched filter corresponding to a value obtained by subtracting 1 from the signal frequency indicated value, wherein the sampling number is a value obtained by subtracting 1 from K times of the signal frequency indicated value, K is an integer and is determined according to the coding type of the complex signal; determining a lead code matched filter corresponding to the maximum value in the matched output values as a lead code matched filter corresponding to the signal frequency indicated value, wherein the sampling number is K times of the signal frequency indicated value; and determining the lead code matched filter corresponding to the maximum value in the matched output values as the lead code matched filter corresponding to the value obtained by adding 1 to the signal frequency indicated value, wherein the sampling number is the value obtained by adding 1 to the K times of the signal frequency indicated value.

Specifically, in practical applications, three preamble matching filters in fig. 8 may be numbered, for example, from top to bottom, a filter No. 1, a filter No. 2, and a filter No. 3 are respectively provided, and each filter corresponds to a corresponding sampling number obtaining manner, for example, the sampling number corresponding to the filter No. 1 is a value obtained by subtracting 1 from K times of the signal frequency indication value, the sampling number corresponding to the filter No. 2 is K times of the signal frequency indication value, and the sampling number corresponding to the filter No. 3 is a value obtained by adding 1 to K times of the signal frequency indication value, so that when the preamble matching filter corresponding to the maximum value among the matching output values determined in the foregoing manner is the filter No. 1, the sampling number may be set to a value obtained by subtracting 1 from K times of the signal frequency indication value, when the preamble matching output value is the filter No. 2, the sampling number may be set to a value obtained by adding 1 to K times of the signal frequency indication value, when the preamble matching output value is the filter No. 3. Then, the waveforms of patterns "0" and "1" in the data to be decoded are sampled based on the number of samples, so that the sampling error caused by the estimation error of the signal frequency indication value can be reduced, and the finally determined number of samples is more accurate.

It should be noted that K is determined according to the encoding type of the complex signal, that is, the encoding type of the tag signal, for example, when FM0 is encoded, K is 1; when the code is miller2, K is 2; when encoded for miller4, K is 4, and so on.

For example, taking miller2 coding as an example, assuming that the estimated signal frequency indication value is n, if the filter corresponding to the peak value output by the maximum matching output detector is filter No. 1, the number of samples in the waveforms of code pattern "0" and code pattern "1" is 2n-1; if the filter corresponding to the peak value output by the maximum matching output detector is the No. 2 filter, the sampling number in the waveforms of the code pattern '0' and the code pattern '1' is 2n; if the filter corresponding to the peak value output by the maximum matching output detector is filter No. 3, the number of samples in the waveforms of code pattern "0" and code pattern "1" is 2n +1.

Further, assuming that the actual returned tag signal has a signal frequency indicating value of 19.6 and an estimated signal frequency indicating value of 20, if the waveform sampling of the code pattern is performed directly based on the estimated signal frequency indicating value 20, the sampling number will be 2 × 20=40, and the actual sampling number should be 2 × 19.6=39.2; and if the sampling number is revised based on the mode, the revised sampling number is 2 × 20-1=39, and 39 is closer to 39.2 than 40, so that the code pattern determined based on the sampling number is more accurate, the determined data to be decoded is more accurate, and the success rate of decoding is improved.

In the above embodiment, the sampling number corresponding to the code pattern in the data to be decoded is determined according to the preamble matched filter corresponding to the maximum value in the matched output value and the signal frequency indication value, so that the accuracy of the sampling number can be effectively improved, the sampling accuracy of the code pattern is improved, the decoding accuracy of the data to be decoded is further improved, and the error rate is lower.

Further, the determining data to be decoded in the complex signal based on the preamble in step 150, and decoding the data to be decoded includes: and decoding the data to be decoded according to the sampling number corresponding to the code pattern and each code pattern in the complex signal from the ending time of the preamble code.

Specifically, referring to fig. 8, the information output by the maximum matching output detector may include a memory address corresponding to the end of the preamble, and the number of samples in the waveforms of the patterns "0" and "1", and after the maximum matching output detector is finished, the memory address corresponding to the end of the preamble may be used as a read start address of the memory, and data to be decoded may be obtained by cyclically reading data from the memory based on the number of samples. Therefore, the data to be decoded is acquired through the corrected sampling number, the accuracy of acquiring the data to be decoded can be improved, the error rate is reduced, and the success rate of decoding is improved.

In some embodiments, the decoding method further comprises: determining whether a complex signal exists according to the signal frequency indication value; if the complex signal is determined to exist, acquiring a lead code; determining that a complex signal is not present, stopping acquisition of the preamble.

Specifically, referring to fig. 8, the signal detection is to determine whether a complex signal exists, and if so, start a timer, where the duration of the timer is the duration of the pilot tone and the preamble; if not, the timer is not started, and the enable signal of the signal detection output is used for enabling the maximum matching output filter. That is to say, a signal detection function is set in the preamble capture process, the detection function is realized by a signal detection module with the functions of enabling and timing, the module is used for judging whether a complex signal exists, if so, a timing is started, meanwhile, a maximum matching output detector is enabled, the duration of the timing is the duration of a pilot tone and a preamble, in the period of time, the corresponding memory address and the number of samples in a waveform corresponding to a code pattern when the maximum matching output detector outputs the preamble are ended, so that the subsequent decoding process normally runs, and after the timing is ended, the enabling is ended, and the maximum matching output detector stops working; if the complex signal does not exist, the timer is not started, and the maximum matching output detector stops working, so that the subsequent decoding process is stopped. Therefore, waste caused by continuous work of the maximum matching output detector due to the absence of the complex signal is avoided, and computing resources are further saved.

In summary, according to the decoding method for the RFID reader according to the embodiment of the present invention, frequency estimation and preamble capture are divided into two stages, the first stage is used for obtaining a signal frequency indication value by signal frequency estimation of a complex signal, and determining a preamble capture coefficient based on the signal frequency indication value, the second stage is used for capturing a preamble based on the preamble capture coefficient, and then decoding of data to be decoded is achieved based on the captured preamble, so that overall computing resource consumption can be greatly reduced, meanwhile, reliability of preamble capture is improved, and then, a decoding success rate of the data to be decoded is improved, and a requirement on a signal-to-noise ratio is low.

In some embodiments, there is also provided a computer-readable storage medium on which a decoding program for an RFID reader is stored, the decoding program for the RFID reader implementing the aforementioned decoding method for the RFID reader when executed by a processor.

In some embodiments, there is also provided an RFID reader, and referring to fig. 9, the RFID reader 100 includes: the memory 110, the processor 120, and the decoding program for the RFID reader/writer, which is stored in the memory 110 and can be run on the processor 120, when the processor 120 executes the program, the decoding method for the RFID reader/writer described above is implemented.

In some embodiments, there is also provided a decoding apparatus for an RFID reader, and referring to fig. 10, the decoding apparatus 200 for an RFID reader includes: a pre-processing module 210, a frequency estimation module 220, a preamble acquisition module 230, and a decoding module 240.

The preprocessing module 210 is configured to preprocess the received tag signal to obtain a complex signal corresponding to the tag signal; the frequency estimation module 220 is configured to perform signal frequency estimation on the complex signal to obtain a signal frequency indication value; the preamble acquisition module 230 is configured to determine a preamble acquisition coefficient according to the signal frequency indication value, and acquire a preamble in the complex signal according to the preamble acquisition coefficient; the decoding module 240 is configured to determine data to be decoded in the complex signal based on the preamble, and decode the data to be decoded.

According to an embodiment of the present invention, referring to fig. 11, the preprocessing module 210 includes: the tag signal processing device comprises a sampling unit 211, a filtering unit 212 and a processing unit 213, wherein the sampling unit 211 is configured to sample and obtain an in-phase signal and a quadrature signal in the tag signal according to a preset sampling rate; the filtering unit 212 is configured to perform filtering processing on the in-phase signal and the quadrature signal; the processing unit 213 is configured to perform phase rotation processing on the filtered in-phase signal and the filtered quadrature signal to obtain a complex signal.

According to an embodiment of the present invention, the frequency estimation module 220 is specifically configured to: determining an oversampling number range corresponding to a pilot tone in the complex signal according to a signal frequency value of the complex signal, a preset frequency deviation range and a preset sampling rate; determining the coefficient of a signal frequency matching filter corresponding to each oversampling number in the oversampling number range; matching the complex signal with a signal frequency matching filter corresponding to each oversampling number to obtain a matching output value corresponding to each oversampling number; and taking the oversampling number corresponding to the maximum value in the matching output values as a signal frequency indication value.

According to an embodiment of the present invention, the preamble capture module 230 is specifically configured to: determining an inverted waveform of the lead code according to the coding type and the standard of the complex signal; and determining a preamble acquisition coefficient according to the signal frequency indication value and the inverted waveform of the preamble.

According to an embodiment of the present invention, the preamble acquisition module 230 is specifically configured to: taking the three preamble capture coefficients as coefficients of three preamble matched filters; matching the complex signal with each lead code matched filter to obtain a matched output value corresponding to each lead code matched filter; and taking the peak time output by the preamble matched filter corresponding to the maximum value in the matched output values as the end time of the preamble.

According to an embodiment of the present invention, the preamble acquisition module 230 is further configured to: and determining the sampling number corresponding to the code pattern in the data to be decoded according to the lead code matched filter corresponding to the maximum value in the matched output values and the signal frequency indicated value.

According to an embodiment of the present invention, the decoding module 240 is specifically configured to: and decoding the data to be decoded according to the sampling number corresponding to the code pattern and each code pattern from the ending time of the preamble code.

According to an embodiment of the present invention, referring to fig. 11, the decoding apparatus for an RFID reader further includes a signal detection module 250, where the signal detection module 250 is configured to: determining whether a complex signal exists according to the signal frequency indication value; determining that the complex signal exists, controlling the preamble acquisition module 230 to acquire the preamble; determining that the complex signal is not present, the preamble acquisition module 230 is controlled to stop acquiring the preamble.

It should be noted that, for the description of the decoding apparatus for the RFID reader in the present application, please refer to the description of the decoding method for the RFID reader in the present application, and detailed description is omitted here.

According to the decoding device for the RFID reader-writer, the frequency estimation and the lead code capture are divided into two stages, the first stage is used for obtaining the signal frequency indicated value through the signal frequency estimation of the complex signal and determining the lead code capture coefficient based on the signal frequency indicated value, the second stage is used for capturing the lead code based on the lead code capture coefficient, and then the decoding of the data to be decoded is achieved based on the captured lead code, so that the overall computing resource consumption can be greatly reduced, the reliability of the lead code capture is improved, the decoding success rate of the data to be decoded is improved, and the requirement on the signal-to-noise ratio is low.

It should be noted that the logic and/or steps represented in the flowcharts or otherwise described herein, such as an ordered listing of executable instructions that can be considered to implement logical functions, can be embodied in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. For the purposes of this description, a "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of the computer-readable medium would include the following: an electrical connection (electronic device) having one or more wires, a portable computer diskette (magnetic device), a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). Additionally, the computer-readable medium could even be paper or another suitable medium upon which the program is printed, as the program can be electronically captured, via for instance optical scanning of the paper or other medium, then compiled, interpreted or otherwise processed in a suitable manner if necessary, and then stored in a computer memory.

It should be understood that portions of the present invention may be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, the various steps or methods may be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, any one or combination of the following technologies, which are well known in the art, may be used: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application specific integrated circuit having an appropriate combinational logic gate circuit, a Programmable Gate Array (PGA), a Field Programmable Gate Array (FPGA), or the like.

In the description of the specification, reference to the description of "one embodiment," "some embodiments," "an example," "a specific example," or "some examples" or the like means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or to implicitly indicate the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.

Claims

1. A decoding method for an RFID reader, the method comprising:

preprocessing the received label signal to obtain a complex signal corresponding to the label signal, comprising: sampling according to a preset sampling rate to obtain an in-phase signal and an orthogonal signal in the label signal; filtering the in-phase signal and the quadrature signal; carrying out phase rotation processing on the filtered in-phase signal and the filtered quadrature signal to obtain the complex signal;

performing signal frequency estimation on the complex signal to obtain a signal frequency indication value, including: determining an oversampling number range corresponding to a pilot tone in the complex signal according to a signal frequency value of the complex signal, a preset frequency deviation range and a preset sampling rate; determining the coefficient of a signal frequency matching filter corresponding to each oversampling number in the oversampling number range; matching the complex signal with a signal frequency matching 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 values as the signal frequency indication value;

determining a lead code acquisition coefficient according to the signal frequency indicating value; determining a preamble acquisition coefficient according to the signal frequency indication value, comprising: determining an inverted waveform of the lead code according to the coding type and standard of the complex signal; determining the preamble acquisition coefficient according to the signal frequency indication value and the inverted waveform of the preamble;

acquiring the preamble in the complex signal according to the preamble acquisition coefficient, comprising: taking the three preamble capture coefficients as coefficients of three preamble matched filters; matching the complex signal with each lead code matched filter to obtain a matched output value corresponding to each lead code matched filter; taking the peak time output by the lead code matched filter corresponding to the maximum value in the matched output values as the end time of the lead code;

determining data to be decoded in the complex signal based on the preamble, and decoding the data to be decoded, including: decoding the data to be decoded according to the sampling number corresponding to the code pattern and each code pattern in the complex signal from the end time of the lead code; and determining the sampling number corresponding to the code pattern in the data to be decoded according to the lead code matched filter corresponding to the maximum value in the matched output values and the signal frequency indicated value.

2. The decoding method for an RFID reader/writer according to claim 1, wherein the filtering process includes at least one of a low-frequency noise filtering process, a direct-current signal filtering process, and a high-frequency signal filtering process.

3. The decoding method for an RFID reader/writer according to claim 1, wherein the pilot tone is a single pilot tone or a multi-pilot tone.

4. The decoding method for an RFID reader/writer according to any one of claims 1 to 3, wherein the preamble acquisition coefficients include three, which are a preamble acquisition coefficient corresponding to a value obtained by subtracting 1 from the signal frequency indication value, a preamble acquisition coefficient corresponding to the signal frequency indication value, and a preamble acquisition coefficient corresponding to a value obtained by adding 1 to the signal frequency indication value.

5. The decoding method for an RFID reader/writer according to claim 1, wherein determining the number of samples corresponding to a code pattern in the data to be decoded according to a preamble matching filter corresponding to a maximum value in the matching output values and the signal frequency indication value includes:

determining a lead code matched filter corresponding to a maximum value in the matched output values as a lead code matched filter corresponding to a value obtained by subtracting 1 from the signal frequency indicated value, wherein the sampling number is a value obtained by subtracting 1 from K times of the signal frequency indicated value, K is an integer, and K is determined according to the coding type of the complex signal;

determining that the lead code matched filter corresponding to the maximum value in the matched output values is the lead code matched filter corresponding to the signal frequency indicated value, wherein the sampling number is K times of the signal frequency indicated value;

and determining that the lead code matched filter corresponding to the maximum value in the matched output values is the lead code matched filter corresponding to the value obtained by adding 1 to the signal frequency indicated value, wherein the sampling number is the value obtained by adding 1 to K times of the signal frequency indicated value.

6. The decoding method for an RFID reader/writer according to claim 1, characterized in that the method further comprises:

determining whether the complex signal exists according to the signal frequency indication value;

acquiring the lead code if the complex signal is determined to exist;

determining that the complex signal is not present, stopping acquisition of the preamble.

7. A computer-readable storage medium, characterized in that a decoding program for an RFID reader is stored thereon, which when executed by a processor implements the decoding method for an RFID reader according to any one of claims 1 to 6.

8. An RFID reader, comprising: memory, processor and decoding program for an RFID reader stored on the memory and executable on the processor, which when executed by the processor implements a decoding method for an RFID reader according to any one of claims 1 to 6.

9. A decoding apparatus for an RFID reader, the apparatus comprising:

the preprocessing module is used for preprocessing the received label signal to obtain a complex signal corresponding to the label signal, and comprises: sampling according to a preset sampling rate to obtain an in-phase signal and an orthogonal signal in the label signal; filtering the in-phase signal and the orthogonal signal; carrying out phase rotation processing on the in-phase signal and the orthogonal signal after filtering processing to obtain the complex signal;

a frequency estimation module, configured to perform signal frequency estimation on the complex signal to obtain a signal frequency indication value, including: determining an oversampling number range corresponding to a pilot tone in the complex signal according to a signal frequency value of the complex signal, a preset frequency deviation range and a preset sampling rate; determining the coefficient of a signal frequency matching filter corresponding to each oversampling number in the oversampling number range; matching the complex signal with a signal frequency matching 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 values as the signal frequency indication value;

a preamble acquisition module, configured to determine a preamble acquisition coefficient according to the signal frequency indication value, and acquire a preamble in the complex signal according to the preamble acquisition coefficient, including: determining an inverted waveform of the lead code according to the coding type and standard of the complex signal; determining the preamble acquisition coefficient according to the signal frequency indication value and the inverted waveform of the preamble; taking the three preamble capture coefficients as coefficients of three preamble matched filters; matching the complex signal with each lead code matched filter to obtain a matched output value corresponding to each lead code matched filter; taking the peak time output by the lead code matching filter corresponding to the maximum value in the matching output values as the end time of the lead code;

a decoding module, configured to determine data to be decoded in the complex signal based on the preamble, and decode the data to be decoded, including: decoding the data to be decoded according to the sampling number corresponding to the code pattern and each code pattern in the complex signal from the end time of the lead code; wherein the preamble acquisition module is further configured to: and determining the sampling number corresponding to the code pattern in the data to be decoded according to the lead code matched filter corresponding to the maximum value in the matched output values and the signal frequency indicated value.

10. The decoding device for an RFID reader/writer according to claim 9, wherein said preprocessing module comprises:

the sampling unit is used for obtaining an in-phase signal and an orthogonal signal in the label signal according to sampling at a preset sampling rate;

the filtering unit is used for carrying out filtering processing on the in-phase signal and the orthogonal signal;

and the processing unit is used for carrying out phase rotation processing on the in-phase signal and the orthogonal signal after filtering processing to obtain the complex signal.

11. The decoding device for the RFID reader/writer according to any one of claims 9 to 10, wherein the preamble acquisition coefficients include three, which are a preamble acquisition coefficient corresponding to a value obtained by subtracting 1 from the signal frequency indication value, a preamble acquisition coefficient corresponding to the signal frequency indication value, and a preamble acquisition coefficient corresponding to a value obtained by adding 1 to the signal frequency indication value.

12. Decoding apparatus for RFID reader/writer according to claim 9,

13. The decoding device for RFID reader/writer according to claim 9 characterized in that said device further comprises a signal detection module for:

if the complex signal is determined to exist, controlling the lead code acquisition module to acquire the lead code;

and if the complex signal is determined not to exist, controlling the preamble code acquisition module to stop acquiring the preamble code.