Method, circuit and device for detecting SOF of single subcarrier, and card machine
By performing autocorrelation operations on the single subcarrier signal sent by the card in the ISO/IEC15693 protocol and counting consecutive half-subcarrier counts, the problem of SOF signal detection errors in non-chip cards is solved, and higher detection accuracy and reliability are achieved.
Patent Information
- Application Number
- CN202411796502.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-09
- Publication Date
- 2025-03-25
AI Technical Summary
In the ISO/IEC15693 protocol, the single sub-carrier SOF signal sent by the card is susceptible to factors such as distance noise in unconnected chip cards, resulting in detection errors.
By performing autocorrelation operations on the input signal to identify the repetitive or periodic mode, count the number of consecutive half-subcarriers, and decode and judge the signal when the correlation peak exceeds the preset threshold and the number of consecutive half-subcarriers is greater than the preset value, the signal is decoded and judged to determine whether the correct single subcarrier SOF exists.
The detection accuracy of the single sub-carrier SOF is improved, errors caused by signal interference or attenuation are reduced, and the reliability of the detection results is enhanced.
Smart Images
Figure CN119696969A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of signal processing technology, for example, to a method, circuit, device, and card machine for detecting a single subcarrier SOF. Background Art
[0002] At present, the single subcarrier mode signal sent by the card in the ISO (International Organization for Standardization) / IEC (International Electrotechnical Commission) 15693 protocol has two speeds: high speed and low speed. The high speed is 26.48kbit / s, the low speed is 6.62kbit / s, and the subcarrier frequency is fc / 32, where fc is the carrier frequency 13.56M. In the ISO / IEC15693 protocol, each frame of the data structure sent by the card has a frame header (Start of Frame, SOF), data, and a frame tail (End Of Frame, EOF). Figure 1 This is a waveform diagram of the SOF of the single subcarrier signal sent by the card received by the card machine in the ISO / IEC15693 protocol. The horizontal axis is time and the vertical axis is the envelope amplitude of the subcarrier. In this waveform, there is first a non-modulated signal with a time length of 768 / fc, which is about 56.64μs, then 24 subcarriers of fc / 32, which is about 56.64μs, and then a coded waveform of data 1, which is about 37.76μs. For the decoder in the card machine, SOF is the starting point and mark of a frame of data, which is related to the correctness of the decoding of the entire frame of data.
[0003] In the related art, the signal is decoded according to the characteristics of the SOF waveform. If a non-modulated signal with a time length of 768 / fc, 24 subcarriers of fc / 32, and a coding waveform of logic 1 are decoded in sequence, it is determined to be a single subcarrier SOF.
[0004] In the process of implementing the embodiments of the present disclosure, it is found that there are at least the following problems in the related art:
[0005] Since the card chip of the ISO / IEC15693 series is a contactless chip, the signal returned to the card machine is greatly affected by factors such as distance noise, which can easily lead to SOF detection errors.
[0006] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present application, and therefore may include information that does not constitute the prior art known to ordinary technicians in the field. Summary of the invention
[0007] In order to provide a basic understanding of some aspects of the disclosed embodiments, a brief summary is given below. The summary is not an extensive review, nor is it intended to identify key / critical components or delineate the scope of protection of these embodiments, but rather serves as a prelude to the detailed description that follows.
[0008] The embodiments of the present disclosure provide a method, circuit, device, and card machine for detecting a single subcarrier SOF, so as to improve the accuracy of detecting a single subcarrier SOF.
[0009] In some embodiments, a method for detecting a single subcarrier SOF includes: performing an autocorrelation operation on an input signal to obtain a correlation peak; counting the number of consecutive half subcarriers of the input signal; when the correlation peak exceeds a preset SOF threshold and the number of consecutive half subcarriers is greater than a preset value, decoding the input signal and outputting decoded data; and judging the decoded data to determine whether a correct single subcarrier SOF exists in the input signal.
[0010] Optionally, when the input signal is a single subcarrier signal, the height of the correlation peak is linearly related to the amplitude of the input signal.
[0011] Optionally, counting the number of consecutive half-subcarriers of the input signal includes: filtering the input signal; detecting the zero-crossing spacing of the filtered signal; and when multiple consecutive zero-crossing spacings meet the half-subcarrier characteristics, taking the number of zero-crossing spacings that meet the half-subcarrier characteristics as the number of consecutive half-subcarriers.
[0012] Optionally, the input signal is decoded and decoded data is output, including: taking the moment when the correlation peak has a maximum value as the ETU (Enhanced Time Unit) boundary of the input signal; dividing each ETU according to the ETU boundary using a cycle count of a preset period; and determining the decoded data according to the relative size of the frequency values of the first half and the second half in each ETU.
[0013] Optionally, judging the decoded data includes: when the correlation peak exceeds a preset SOF threshold and the number of consecutive half subcarriers is greater than a preset value, if in a subsequent ETU, the decoded data is a preset logic value, it is determined to be a correct single subcarrier SOF.
[0014] Optionally, the preset SOF threshold is determined in the following manner: a transmission process of a single subcarrier signal is simulated to determine an initial value of the SOF threshold; and the initial value of the SOF threshold is adjusted according to an external input stimulus to obtain a preset SOF threshold.
[0015] Optionally, the preset value of the number of consecutive half subcarriers is determined in the following manner: obtaining the amplitude of the input signal; determining the preset value of the number of consecutive half subcarriers based on the amplitude of the input signal; when the amplitude of the input signal is low, setting the preset value of the number of consecutive half subcarriers to a lower value.
[0016] In some embodiments, a circuit for detecting a single subcarrier SOF includes: a correlator circuit configured to perform an autocorrelation operation on an input signal to obtain a correlation peak; a continuous half-subcarrier detection circuit configured to count the number of continuous half-subcarriers of the input signal; a decoding circuit configured to decode the input signal and output decoded data when the correlation peak exceeds a preset SOF threshold and the number of continuous half-subcarriers is greater than a preset value; and a decision circuit configured to judge the decoded data to determine whether a correct single subcarrier SOF exists in the input signal.
[0017] In some embodiments, an apparatus for detecting a single subcarrier SOF includes a processor and a memory storing program instructions, wherein the processor is configured to execute the above-mentioned method for detecting a single subcarrier SOF when executing the program instructions.
[0018] In some embodiments, the card machine includes: a card machine body; a circuit for detecting single subcarrier SOF as described above, or a device for detecting single subcarrier SOF as described above, installed in the card machine body.
[0019] The method, circuit, device, and card machine for detecting single subcarrier SOF provided by the embodiments of the present disclosure can achieve the following technical effects:
[0020] In the embodiment of the present disclosure, an autocorrelation operation is performed on the input signal, and a repetitive or periodic pattern in the input signal can be identified. When the correlation peak exceeds the preset SOF threshold, it indicates that there is a pattern matching the SOF feature in the input signal. The number of continuous half-subcarriers of the input signal is counted. When the number of continuous half-subcarriers is greater than the preset value, it indicates that there are a sufficient number of continuous half-subcarriers in the input signal to verify the validity of the SOF signal. When the above two conditions are met, it can ensure that the input signal is decoded at the correct time point, improve the accuracy of the detection of single subcarrier SOF, and output more accurate decoded data. Finally, the decoded data is judged to determine whether there is a correct single subcarrier SOF in the input signal. Therefore, the embodiment of the present disclosure can reduce errors caused by signal interference or attenuation by combining the correlation peak of the input signal, the number of continuous half-subcarriers, and the decoded data, and improve the accuracy and reliability of the single subcarrier SOF detection result.
[0021] The above general description and the following description are exemplary and explanatory only and are not intended to limit the present application. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] One or more embodiments are exemplarily described by corresponding drawings, which do not limit the embodiments. Elements with the same reference numerals in the drawings are shown as similar elements, and the drawings do not constitute a scale limitation, and wherein:
[0023] Figure 1 It is a schematic diagram of the SOF waveform of a single subcarrier signal;
[0024] Figure 2 is a circuit block diagram of a circuit for detecting a single subcarrier SOF provided by an embodiment of the present disclosure;
[0025] Figure 3 is a schematic diagram of a method for detecting a single subcarrier SOF provided by an embodiment of the present disclosure;
[0026] Figure 4 It is a schematic diagram of a coding waveform in which the data value of a single subcarrier signal is 0;
[0027] Figure 5 is a schematic diagram of a coding waveform in which the data value of a single subcarrier signal is 1;
[0028] Figure 6 It is a schematic diagram of a device for detecting a single subcarrier SOF provided by an embodiment of the present disclosure. DETAILED DESCRIPTION
[0029] In order to be able to understand the features and technical contents of the embodiments of the present disclosure in more detail, the implementation of the embodiments of the present disclosure is described in detail below in conjunction with the accompanying drawings. The attached drawings are for reference only and are not used to limit the embodiments of the present disclosure. In the following technical description, for the convenience of explanation, a full understanding of the disclosed embodiments is provided through multiple details. However, one or more embodiments can still be implemented without these details. In other cases, to simplify the drawings, well-known structures and devices can be simplified for display.
[0030] The terms "first", "second", etc. in the technical solutions described in this application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so as to describe the embodiments of the disclosed embodiments described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions.
[0031] Unless otherwise stated, the term "plurality" means two or more.
[0032] In the embodiment of the present disclosure, the character " / " indicates that the preceding and following objects are in an "or" relationship. For example, A / B indicates: A or B.
[0033] The term "and / or" is a description of the association relationship between objects, indicating that three relationships can exist. For example, A and / or B means: A or B, or, A and B.
[0034] The term "correspondence" may refer to an association relationship or a binding relationship. The correspondence between A and B means that there is an association relationship or a binding relationship between A and B.
[0035] Combination Figure 2 As shown, the embodiment of the present disclosure provides a circuit for detecting a single subcarrier SOF, including: a correlator circuit 10, a continuous half subcarrier detection circuit 20, a decoding circuit 30, and a decision circuit 40. The correlator circuit 10 is connected to the decoding circuit 30, the continuous half subcarrier detection circuit 20 is connected to the decoding circuit 30, and the decoding circuit 30 is connected to the decision circuit 40.
[0036] The correlator circuit 10 is configured to perform an autocorrelation operation on the input signal to obtain a correlation peak. The continuous half-subcarrier detection circuit 20 is configured to count the number of continuous half-subcarriers of the input signal. The decoding circuit 30 is configured to decode the input signal and output decoded data when the correlation peak exceeds a preset SOF threshold and the number of continuous half-subcarriers is greater than a preset value. The decision circuit 40 is configured to judge the decoded data to determine whether there is a correct single subcarrier SOF in the input signal.
[0037] The present disclosure provides a method for detecting a single subcarrier SOF by applying the above-mentioned circuit for detecting a single subcarrier SOF. Figure 3 As shown, the method includes:
[0038] S101, the correlator circuit performs autocorrelation operation on the input signal to obtain a correlation peak.
[0039] S102: A continuous half-subcarrier detection circuit counts the number of continuous half-subcarriers of an input signal.
[0040] S103, the decoding circuit decodes the input signal and outputs decoded data when the correlation peak exceeds a preset SOF threshold and the number of consecutive half subcarriers is greater than a preset value.
[0041] S104, the decision circuit makes a decision on the decoded data to determine whether a correct single subcarrier SOF exists in the input signal.
[0042] In the embodiment of the present disclosure, the input signal is autocorrelated by the correlator circuit, and the repetitive or periodic pattern in the input signal can be identified. When the correlation peak exceeds the preset SOF threshold, it indicates that there is a pattern matching the SOF feature in the input signal. The continuous half-subcarrier detection circuit counts the number of continuous half-subcarriers of the input signal. When the number of continuous half-subcarriers is greater than the preset value, it indicates that there are a sufficient number of continuous half-subcarriers in the input signal to verify the validity of the SOF signal. When the above two conditions are met, it can be ensured that the decoding circuit decodes the input signal at the correct time point, improves the accuracy of the detection of the single subcarrier SOF, and outputs more accurate decoding data. Finally, the decoded data is judged by the decision circuit to determine whether there is a correct single subcarrier SOF in the input signal. Therefore, the embodiment of the present disclosure can reduce the errors caused by signal interference or attenuation by combining the correlation peak of the input signal, the number of continuous half-subcarriers, and the decoded data, and improves the accuracy and reliability of the single subcarrier SOF detection result.
[0043] Optionally, when the input signal is a single subcarrier signal, the height of the correlation peak is linearly related to the amplitude of the input signal.
[0044] In this embodiment, the correlator circuit performs autocorrelation operation on the single subcarrier signal, and can convert the amplitude of the single subcarrier signal into the height value of the correlation peak, and the height of the correlation peak is linearly related to the amplitude of the single subcarrier signal. Figure 1 The single subcarrier SOF shown in the figure has an ETU of 37.76μs. The entire SOF includes 4 ETUs, and the fourth ETU is a normal logic "1". However, logic "1" does not improve the discrimination of the autocorrelation result much. Therefore, the correlator circuit only performs autocorrelation operation on the first three ETUs of the SOF to obtain the corresponding correlation peak. When the correlation peak exceeds the preset SOF threshold, it means that there is a pattern matching the SOF feature in the input signal, that is, SOF may exist.
[0045] Optionally, counting the number of consecutive half-subcarriers of the input signal includes: filtering the input signal; detecting the zero-crossing spacing of the filtered signal; and when multiple consecutive zero-crossing spacings meet the half-subcarrier characteristics, taking the number of zero-crossing spacings that meet the half-subcarrier characteristics as the number of consecutive half-subcarriers.
[0046] In this embodiment, the input signal first passes through a filter to remove noise and extract the part of interest in the signal. The filter is designed to pass the frequency components related to the ISO / IEC15693 protocol. Then the zero crossing point in the filtered signal is detected, that is, the point where the signal changes from positive to negative or from negative to positive. The zero crossing point is an important feature of the signal waveform and can be used to identify the subcarrier. The time interval between consecutive zero crossing points is measured. In the ISO / IEC15693 protocol, the frequency of the subcarrier is fc / 32, so the spacing between consecutive half subcarriers should be half of the subcarrier period. If the measured zero crossing point spacing meets the characteristics of the half subcarrier, that is, it meets half of the expected subcarrier period, it is considered that there is a valid half subcarrier in the signal. Whenever a half subcarrier that meets the characteristics is detected, the continuous half subcarrier counter is incremented by 1 to track the number of consecutive half subcarriers. If at a certain point, the zero crossing point spacing no longer meets the characteristics of the half subcarrier, the counter will be cleared to indicate the end of the continuous half subcarrier sequence. Therefore, the value of the counter is the number of consecutive zero crossing point spacings that meet the characteristics of the half subcarrier.
[0047] Optionally, the input signal is decoded and decoded data is output, including: taking the moment when the correlation peak has a maximum value as the ETU boundary of the input signal; dividing each ETU according to the ETU boundary using a cycle count of a preset period; and determining the decoded data according to the relative size of the frequency values of the first half and the second half in each ETU.
[0048] In this embodiment, by judging the correlation peak and the number of consecutive half subcarriers, the decoding circuit can decode the input signal at the correct time point. The moment when the correlation peak appears to be the maximum value is used as the ETU boundary, and the subsequent data decoding process can be synchronized. According to the ETU boundary, each ETU can be determined, and then the cyclic technology of the preset period is used to divide each ETU. The relative size of the frequency value of the first half and the second half of each ETU is analyzed to determine the decoded data. This process ensures the accurate decoding of the data frame, so as to correctly recover and process the transmitted data.
[0049] In an optional embodiment, each ETU is divided into 8 equal parts using a cycle count with a preset period of 8. The frequency mean when the cycle count is 1 and 2 is calculated to represent the frequency value of the first half of the ETU; the frequency mean when the cycle count is 5 and 6 is calculated to represent the frequency value of the second half of the ETU. By comparing the frequency values of the first half and the second half of the ETU, the logic value represented by each ETU can be determined. Figure 4 As shown, if the frequency value of the first half of the ETU is greater than the frequency value of the second half, it is decoded as logic "0". Figure 5As shown, if the frequency value of the first half of the ETU is less than or equal to the frequency value of the second half, it is decoded as logic "1".
[0050] Optionally, judging the decoded data includes: when the correlation peak exceeds a preset SOF threshold and the number of consecutive half subcarriers is greater than a preset value, if in a subsequent ETU, the decoded data is a preset logic value, it is determined to be a correct single subcarrier SOF.
[0051] In this embodiment, the decision logic of the decision circuit involves the synchronous satisfaction of multiple conditions, so as to ensure the correct detection of the SOF signal. First, the correlator circuit outputs a correlation peak that matches the SOF feature. When the correlation peak exceeds the preset SOF threshold, it indicates that the signal may have the feature of SOF. Then, the continuous half-subcarrier detection circuit detects the number of continuous half-subcarriers in the input signal. When the number of continuous half-subcarriers is greater than the preset value, it further supports the possibility of the existence of SOF in the input signal. After confirming the two conditions of the correlation peak and the number of continuous half-subcarriers, the logic value decoded by the decoding circuit in the subsequent ETU is finally checked. According to the ISO / IEC15693 protocol, SOF is followed by a logic "1". Therefore, if the logic value decoded by the decoder in the next ETU is "1" after the maximum value of the correlation peak appears as the ETU boundary, this further verifies the existence of SOF. Therefore, only when the above three conditions are met at the same time, the decision circuit will finally confirm that the detected signal is a correct SOF, ensuring the high accuracy and reliability of SOF detection and reducing the possibility of misjudgment. When SOF is confirmed, it can be synchronized and prepared to receive and decode the subsequent data frame. If any of the conditions is not met, it means that the currently detected signal may not be SOF, and it is necessary to continue to monitor subsequent signals or request retransmission. Using this decision logic that integrates multiple detection results, the card machine decoder of the ISO / IEC15693 protocol can more accurately identify the beginning of the data frame, thereby ensuring the synchronization and integrity of data transmission.
[0052] Optionally, the preset SOF threshold is determined in the following manner: a transmission process of a single subcarrier signal is simulated to determine an initial value of the SOF threshold; and the initial value of the SOF threshold is adjusted according to an external input stimulus to obtain a preset SOF threshold.
[0053] In this embodiment, a simulation model is established in MATLAB to simulate the transmission process of a single subcarrier signal, including the generation, transmission and reception of the signal. First, a simulated single subcarrier signal is generated that complies with the ISO / IEC15693 protocol, including SOF, data bits and EOF. In order to simulate the signal in the actual environment, noise and attenuation can also be added to the simulated signal to simulate the influence of distance and environment on the signal. An autocorrelation operation is performed on the received signal to detect the characteristics of SOF. The correlation peaks in the result of the autocorrelation operation are observed, and these peaks correspond to the characteristics of the SOF signal. According to the result of the autocorrelation operation, an initial SOF threshold is determined. This threshold should be higher than the noise level but lower than the minimum value of the SOF characteristic peak to ensure that SOF can be accurately detected. By adjusting the threshold, the influence on the accuracy of SOF detection is observed, and the threshold is optimized to improve the accuracy and robustness of detection. The initial value of the SOF threshold can be adjusted according to external input excitation, such as different signal strengths, noise levels or transmission distances. Among them, changes in signal strength will affect the height of the correlation peak. In the case of weak signals, the threshold needs to be lowered to ensure that SOF is detected; an increase in noise level may affect the clarity of the correlation peak. In a high-noise environment, the threshold needs to be adjusted to reduce false detections; an increase in transmission distance may cause signal attenuation, affecting the detection of SOF. In long-distance transmission, the threshold needs to be adjusted to adapt to signal attenuation. In practical applications, an adaptive algorithm can be developed to dynamically adjust the SOF threshold based on the real-time measured signal strength and noise level. Or use machine learning methods, such as neural networks, to learn the optimal threshold under different conditions based on historical data.
[0054] Optionally, the preset SOF threshold value ranges from [64, 128]. The default value of the preset SOF threshold value may be 80.
[0055] Optionally, the preset value of the number of consecutive half subcarriers is determined in the following manner: obtaining the amplitude of the input signal; determining the preset value of the number of consecutive half subcarriers based on the amplitude of the input signal; when the amplitude of the input signal is low, setting the preset value of the number of consecutive half subcarriers to a lower value.
[0056] In this embodiment, the preset value of the number of consecutive half-subcarriers is determined according to the amplitude of the input signal by measuring or estimating the amplitude of the input signal. This preset value is a standard for judging whether the number of consecutive half-subcarriers is sufficient when detecting SOF. When the amplitude of the input signal is low, it means that the signal may be weak. At this time, the preset value of the number of consecutive half-subcarriers should be lowered, so that SOF can be detected even when the signal is weak, thereby improving the sensitivity and robustness of the detection. In a specific embodiment, an algorithm or a lookup table can be designed to dynamically adjust the preset value of the number of consecutive half-subcarriers according to the amplitude of the input signal. For example, an amplitude threshold can be set, and when the signal amplitude is lower than this threshold, the preset value is lowered.
[0057] Optionally, the preset value of the number of consecutive half subcarriers is in a range of [4, 24]. The default value of the preset value of the number of consecutive half subcarriers may be 6.
[0058] Combination Figure 6 As shown, an embodiment of the present disclosure provides a device 300 for detecting a single subcarrier SOF, including a processor 200 and a memory 201. Optionally, the device may also include a communication interface 202 and a bus 203. The processor 200, the communication interface 202, and the memory 201 may communicate with each other through the bus 203. The communication interface 202 may be used for information transmission. The processor 200 may call the logic instructions in the memory 201 to execute the method for detecting a single subcarrier SOF of the above embodiment.
[0059] In addition, the logic instructions in the memory 201 described above may be implemented in the form of software functional units and when sold or used as independent products, may be stored in a computer-readable storage medium.
[0060] The memory 201, as a computer-readable storage medium, can be used to store software programs, computer executable programs, such as program instructions / modules corresponding to the method in the embodiment of the present disclosure. The processor 200 executes the function application and data processing by running the program instructions / modules stored in the memory 201, that is, the method for detecting a single subcarrier SOF in the above embodiment is implemented.
[0061] The memory 201 may include a program storage area and a data storage area, wherein the program storage area may store an operating system and an application required for at least one function; the data storage area may store data created according to the use of the terminal device, etc. In addition, the memory 201 may include a high-speed random access memory and may also include a non-volatile memory.
[0062] The disclosed embodiment provides a card machine, including: a card machine body, and the above-mentioned device for detecting single subcarrier SOF. The device for detecting single subcarrier SOF is installed in the card machine body. The installation relationship described here is not limited to placement inside the card machine, but also includes installation connections with other components of the card machine, including but not limited to physical connections, electrical connections or signal transmission connections. It can be understood by those skilled in the art that the device for detecting single subcarrier SOF can be adapted to a feasible card machine body, thereby realizing other feasible embodiments.
[0063] An embodiment of the present disclosure provides a computer-readable storage medium storing computer-executable instructions, wherein the computer-executable instructions are configured to execute the above method for detecting a single subcarrier SOF.
[0064] The technical solution of the embodiment of the present disclosure can be embodied in the form of a software product, which is stored in a storage medium and includes one or more instructions for enabling a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in the embodiment of the present disclosure. The aforementioned storage medium may be a non-transient storage medium, including: a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, and other media that can store program codes.
[0065] The above description and accompanying drawings fully illustrate the embodiments of the present disclosure so that those skilled in the art can practice them. Other embodiments may include structural, logical, electrical, process and other changes. The embodiments represent possible changes only. Unless explicitly required, separate components and functions are optional, and the order of operation may vary. The parts and features of some embodiments may be included in or replace the parts and features of other embodiments. Moreover, the words used in this application are only used to describe the embodiments and are not used to limit the technical solutions recorded in this application. As used in the technical solutions recorded in this application, unless the context clearly indicates, the singular forms of "a", "an" and "the" are intended to include plural forms as well. Similarly, the term "and / or" as used in this application refers to any and all possible combinations of listings containing one or more associated ones. In addition, when used in the present application, the term "comprise" and its variants "comprises" and / or comprising refer to the presence of stated features, wholes, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or groups thereof. In the absence of further restrictions, the elements defined by the sentence "comprising a ..." do not exclude the presence of other identical elements in the process, method or device comprising the elements. In this article, each embodiment may focus on the differences from other embodiments, and the same and similar parts between the various embodiments may refer to each other. For the methods, products, etc. disclosed in the embodiments, if they correspond to the method part disclosed in the embodiments, then the relevant parts can refer to the description of the method part.
[0066] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software may depend on the specific application and design constraints of the technical solution. The technicians may use different methods for each specific application to implement the described functions, but such implementations should not be considered to exceed the scope of the embodiments of the present disclosure. The technicians may clearly understand that, for the convenience and simplicity of description, the specific working processes of the systems, devices and units described above may refer to the corresponding processes in the aforementioned method embodiments, and will not be repeated here.
[0067] In the embodiments disclosed herein, the disclosed methods and products (including but not limited to devices, equipment, etc.) can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units can be only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between each other shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms. The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the units may be selected according to actual needs to implement this embodiment. In addition, each functional unit in the embodiment of the present disclosure may be integrated in a processing unit, or each unit may exist physically alone, or two or more units may be integrated in one unit.
[0068] The flowchart and block diagram in the accompanying drawings show the possible architecture, function and operation of the system, method and computer program product according to the embodiment of the present disclosure. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a part of the code, and the module, the program segment or a part of the code contains one or more executable instructions for realizing the specified logical function. In some alternative implementations, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, which can depend on the functions involved. In the description corresponding to the flowchart and the block diagram in the accompanying drawings, the operations or steps corresponding to different boxes can also occur in a different order from the order disclosed in the description, and sometimes there is no specific order between different operations or steps. For example, two consecutive operations or steps can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, which can depend on the functions involved. Each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, may be implemented by a dedicated hardware-based system that performs the specified functions or actions, or may be implemented by a combination of dedicated hardware and computer instructions.
Claims
1. A method for detecting a single subcarrier SOF, characterized in that: include: Perform autocorrelation operation on the input signal to obtain the correlation peak; Counting the number of consecutive half subcarriers of the input signal; When the correlation peak exceeds a preset SOF threshold and the number of consecutive half subcarriers is greater than a preset value, the input signal is decoded and decoded data is output; The decoded data is judged to determine whether a correct single subcarrier SOF exists in the input signal.
2. The method according to claim 1, characterized in that When the input signal is a single subcarrier signal, the height of the correlation peak is linearly related to the amplitude of the input signal.
3. The method according to claim 1, characterized in that Count the number of consecutive half subcarriers of the input signal, including: Filter the input signal; Detecting the zero-crossing interval of the filtered signal; In the case where a plurality of continuous zero-crossing point intervals all meet the half-subcarrier characteristic, the number of zero-crossing point intervals meeting the half-subcarrier characteristic is used as the number of continuous half-subcarriers.
4. The method according to claim 1, characterized in that: Decode the input signal and output decoded data, including: The moment when the correlation peak reaches its maximum value is taken as the ETU boundary of the input signal; According to the ETU boundary, each ETU is divided using a cycle count of a preset period; The decoded data is determined according to the relative magnitudes of the frequency values of the first half and the second half in each ETU.
5. The method according to claim 4, characterized in that Judge the decoded data, including: When the correlation peak exceeds the preset SOF threshold and the number of consecutive half subcarriers is greater than a preset value, if the decoded data is a preset logic value in a subsequent ETU, it is determined to be a correct single subcarrier SOF.
6. The method according to any one of claims 1 to 5, characterized in that: The preset SOF threshold is determined as follows: Simulate the transmission process of a single subcarrier signal to determine the initial value of the SOF threshold; According to the external input stimulus, the initial value of the SOF threshold is adjusted to obtain a preset SOF threshold.
7. The method according to any one of claims 1 to 5, characterized in that: The preset value of the number of consecutive half subcarriers is determined as follows: Get the amplitude of the input signal; The preset value of the number of consecutive half subcarriers is determined according to the amplitude of the input signal; when the amplitude of the input signal is low, the preset value of the number of consecutive half subcarriers is set to a low value.
8. A circuit for detecting a single subcarrier SOF, characterized in that: include: The correlator circuit is configured to perform an autocorrelation operation on the input signal to obtain a correlation peak; A continuous half-subcarrier detection circuit is configured to count the number of continuous half-subcarriers of an input signal; A decoding circuit is configured to decode the input signal and output decoded data when the correlation peak exceeds a preset SOF threshold and the number of consecutive half subcarriers is greater than a preset value; The decision circuit is configured to make a decision on the decoded data to determine whether a correct single subcarrier SOF exists in the input signal.
9. A device for detecting a single subcarrier SOF, comprising a processor and a memory storing program instructions, characterized in that: The processor is configured to execute the method for detecting a single subcarrier SOF according to any one of claims 1 to 7 when running the program instructions.
10. A card machine, characterized in that: include: Card machine body; The circuit for detecting single subcarrier SOF as claimed in claim 8, or the device for detecting single subcarrier SOF as claimed in claim 9, is installed in the card machine body.