Demodulation method and demodulation device for NFC (Near Field Communication) signal and NFC equipment

Abstract

The invention relates to the technical field of near field communication, and discloses a demodulation method and a demodulation device for an NFC (Near Field Communication) signal, and NFC equipment. The demodulation method comprises the following steps: receiving an NFC signal, and preprocessing the NFC signal to obtain an I-path digital signal and a Q-path digital signal of the NFC signal; calculating a first signal-to-noise ratio and a first symbol value of the I-path digital signal, and a second signal-to-noise ratio and a second symbol value of the Q-path digital signal; according to the first signal-to-noise ratio, the second signal-to-noise ratio, the first symbol value and the second symbol value, determining a target-path signal in the I-path digital signal, the Q-path digital signal and a combined signal of the I-path digital signal and the Q-path digital signal; and demodulating the target path signal, and determining information transmitted by the NFC signal. According to the application, one path of digital signal or a combined signal of two paths of digital signals with concentrated energy can be automatically selected for demodulation, so that the accuracy of demodulating NFC signal transmission information can be improved.

Description

Technical Field

[0001] The present application relates to the field of near field communication technology, for example, to a demodulation method and a demodulation device for NFC signals, and an NFC device. Background Art

[0002] At present, NFC near-field communication has three working modes: card emulation mode, read-write mode and point-to-point communication mode. Electronic devices with NFC function can perform contactless point-to-point data transmission, thereby conveniently and safely completing information exchange and access to content and services. It is widely used in access control, public transportation, mobile payment and other fields.

[0003] In the related art, for the point-to-point data transmission mode, after receiving the NFC signal, the NFC device (ie, the NFC receiver) processes the NFC signal into an I-channel digital signal and a Q-channel digital signal, and then selects one of the digital signals for demodulation.

[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] In actual application environments, due to interference from various factors (such as quality differences in NFC devices, imperfect NFC chip manufacturing processes, etc.), the digital signal selected for demodulation may not be accurate, and the energy of the NFC signal may be concentrated on the unselected digital signal, or it may be distributed on both signals at the same time, resulting in a loss of demodulation performance and failure to correctly demodulate the transmitted information. Therefore, when receiving an NFC signal, how to improve the accuracy of demodulating the information transmitted by the NFC signal has become a technical problem that needs to be solved urgently.

[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 demodulation method and a demodulation device for NFC signals, and an NFC device, which can improve the accuracy of demodulating NFC signal transmission information.

[0009] In some embodiments, a demodulation method for an NFC signal includes: receiving an NFC signal, and preprocessing the NFC signal to obtain an I-channel digital signal and a Q-channel digital signal of the NFC signal; calculating a first signal-to-noise ratio and a first symbol value of the I-channel digital signal, and a second signal-to-noise ratio and a second symbol value of the Q-channel digital signal; determining a target channel signal among the I-channel digital signal, the Q-channel digital signal, and a combined signal of the I-channel and Q-channel digital signals based on the first signal-to-noise ratio, the second signal-to-noise ratio, the first symbol value, and the second symbol value; and demodulating the target channel signal to determine information transmitted by the NFC signal.

[0010] Optionally, determining a target channel signal among an I-channel digital signal, a Q-channel digital signal, and a combined signal of the I-channel and Q-channel digital signals according to the first signal-to-noise ratio, the second signal-to-noise ratio, the first symbol value, and the second symbol value includes: when a difference between the first signal-to-noise ratio and the second signal-to-noise ratio is greater than a set threshold, adopting the I-channel digital signal as the target channel signal; when a difference between the second signal-to-noise ratio and the first signal-to-noise ratio is greater than the set threshold, adopting the Q-channel digital signal as the target channel signal; and when an absolute value of the difference between the first signal-to-noise ratio and the second signal-to-noise ratio is less than or equal to the set threshold, determining the target channel signal among the I-channel digital signal, the Q-channel digital signal, and a combined signal of the I-channel and Q-channel digital signals according to the first symbol value and the second symbol value.

[0011] Optionally, determining a target path signal among an I-path digital signal, a Q-path digital signal, and a combined signal of the I-path and Q-path digital signals according to the first symbol value and the second symbol value includes: when the number of corresponding point symbols in the first symbol value and the second symbol value that are identical or opposite is greater than or equal to a set number, using the combined signal of the I-path and Q-path digital signals as the target path signal; when the number of corresponding point symbols in the first symbol value and the second symbol value that are identical or opposite is less than a set number, if the first signal-to-noise ratio is greater than the second signal-to-noise ratio, using the I-path digital signal as the target path signal; if the first signal-to-noise ratio is less than or equal to the second signal-to-noise ratio, using the Q-path digital signal as the target path signal.

[0012] Optionally, when the number of corresponding point symbols in the first symbol value and the second symbol value that are the same is greater than or equal to a set number, the combined signal of the I-channel and Q-channel digital signals is calculated using the following expression:

[0013]

[0014] When the number of corresponding points with opposite signs in the first symbol value and the second symbol value is greater than or equal to the set number, the combined signal of the I-channel and Q-channel digital signals is calculated using the following expression:

[0015]

[0016] Among them, Cadp(n) is the combined signal of the I-channel and Q-channel digital signals, CI(n) is the I-channel digital signal, and CQ(n) is the Q-channel digital signal.

[0017] Optionally, calculating a first signal-to-noise ratio and a first symbol value of an I-channel digital signal, and a second signal-to-noise ratio and a second symbol value of a Q-channel digital signal, includes: calculating a first correlation value of the I-channel digital signal and a second correlation value of the Q-channel digital signal; calculating a first power value and a first symbol value of the I-channel according to the first correlation value, and calculating a second power value and a second symbol value of the Q-channel according to the second correlation value; calculating a first signal-to-noise ratio of the I-channel according to the first power value, and calculating a second signal-to-noise ratio of the Q-channel according to the second power value.

[0018] Optionally, preprocessing the NFC signal includes: amplifying the NFC signal; and performing orthogonal down-conversion on the amplified NFC signal to obtain an I-channel digital signal and a Q-channel digital signal.

[0019] Optionally, before performing orthogonal down-conversion on the amplified NFC signal, the demodulation method further includes: performing filtering processing on the amplified NFC signal to suppress interference and noise of the NFC signal.

[0020] In some embodiments, a demodulation device for NFC signals includes: a processing module configured to receive an NFC signal and pre-process the NFC signal to obtain an I-channel digital signal and a Q-channel digital signal of the NFC signal; a calculation module configured to calculate a first signal-to-noise ratio and a first symbol value of the I-channel digital signal, and a second signal-to-noise ratio and a second symbol value of the Q-channel digital signal; a determination module configured to determine a target channel signal among the I-channel digital signal, the Q-channel digital signal, and a combined channel signal of the I-channel and Q-channel digital signals based on the first signal-to-noise ratio, the second signal-to-noise ratio, the first symbol value, and the second symbol value; and a demodulation module configured to demodulate the target channel signal to determine information transmitted by the NFC signal.

[0021] In some embodiments, a demodulation device for NFC signals includes a processor and a memory storing program instructions, and the processor is configured to execute the above-mentioned demodulation method for NFC signals when running the program instructions.

[0022] In some embodiments, an NFC device includes: a device body; and a demodulation device for NFC signals as described above, disposed in the device body.

[0023] The demodulation method and demodulation device for NFC signals and the NFC device provided in the embodiments of the present disclosure can achieve the following technical effects:

[0024] In the embodiment of the present disclosure, after the received NFC signal is processed into an I-channel digital signal and a Q-channel digital signal, the first signal-to-noise ratio and the first symbol value of the I-channel digital signal, as well as the second signal-to-noise ratio and the second symbol value of the Q-channel digital signal are first calculated respectively. Then, based on the first signal-to-noise ratio, the second signal-to-noise ratio, the first symbol value and the second symbol value, the target channel signal that is most suitable for demodulation among the I-channel digital signal, the Q-channel digital signal and the combined signal of the I-channel and Q-channel digital signals is determined. Finally, the target channel signal is demodulated to determine the information transmitted by the NFC signal. In this way, a digital signal with concentrated energy or a combined signal of two digital signals can be automatically selected for demodulation. Therefore, the embodiment of the present disclosure can improve the accuracy of demodulating information transmitted by the NFC signal.

[0025] 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

[0026] 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:

[0027] Figure 1 is a schematic diagram of an NFC device provided by an embodiment of the present disclosure;

[0028] Figure 2 is a schematic diagram of a demodulation method for NFC signals provided by an embodiment of the present disclosure;

[0029] Figure 3 is a schematic diagram of another demodulation method for NFC signals provided by an embodiment of the present disclosure;

[0030] Figure 4 is a schematic diagram of another demodulation method for NFC signals provided by an embodiment of the present disclosure;

[0031] Figure 5 is a schematic diagram of a demodulation device for NFC signals provided by an embodiment of the present disclosure;

[0032] Figure 6 is a schematic diagram of another demodulation device for NFC signals provided by an embodiment of the present disclosure. DETAILED DESCRIPTION

[0033] 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.

[0034] The terms "first", "second", etc. in the specification and claims of the embodiments of the present disclosure and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchanged where appropriate, so that the embodiments of the embodiments of the present disclosure described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions.

[0035] Unless otherwise stated, the term "plurality" of a feature means two or more.

[0036] In the embodiment of the present disclosure, the character " / " feature indicates that the preceding and following objects are in an "or" relationship. For example, the A / B feature indicates: A or B.

[0037] The term "and / or" is a description of the association relationship between objects, and the characteristic indicates that there can be three relationships. For example, A and / or B, the characteristic indicates: A or B, or, A and B.

[0038] 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.

[0039] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present disclosure may be combined with each other.

[0040] In the embodiments of the present disclosure, an NFC device refers to a proximity coupling device (PCD), for example, a smartphone, a tablet computer, and an NFC receiver such as an NFC reader / writer. Figure 1 As shown, the NFC device includes a device body 110 and a demodulation device 500 (600) for NFC signals.

[0041] Specifically, the demodulation device 500 ( 600 ) for NFC signals is disposed in the device body 110 .

[0042] Optionally, the demodulation device 600 for NFC signals includes a processor, which can pre-process the received NFC signal to obtain an I-channel digital signal and a Q-channel digital signal of the NFC signal. The target channel signal with concentrated energy among the I-channel digital signal, the Q-channel digital signal, and the combined signal of the I-channel and Q-channel digital signals can be determined by calculating the first signal-to-noise ratio and the first symbol value of the I-channel digital signal, and the second signal-to-noise ratio and the second symbol value of the Q-channel digital signal. The target channel signal can be demodulated to determine the information transmitted by the NFC signal.

[0043] In combination with the above-mentioned NFC device, the present disclosure provides a demodulation method for NFC signals, such as Figure 2 As shown, the demodulation method includes:

[0044] S201, the processor receives an NFC signal, and pre-processes the NFC signal to obtain an I-channel digital signal and a Q-channel digital signal of the NFC signal.

[0045] Specifically, the NFC signal refers to a radio frequency signal emitted when a proximity integrated circuit card (PICC) is close to an NFC device. An antenna device is provided on the NFC device, and the processor can collect and receive the NFC signal through the antenna device.

[0046] Specifically, the principle of NFC near-field communication technology is to use orthogonal modulation technology to achieve signal transmission. Orthogonal modulation is a method of dividing the original signal into real and imaginary parts (or I and Q) for modulation. This modulation method can separate NFC signals in the frequency domain, improving the efficiency and anti-interference ability of signal transmission. Therefore, after receiving the NFC signal, the NFC signal needs to be preprocessed into I digital signal and Q digital signal.

[0047] Optionally, preprocessing the NFC signal includes: amplifying the NFC signal; and performing orthogonal down-conversion on the amplified NFC signal to obtain an I-channel digital signal and a Q-channel digital signal.

[0048] Specifically, a low noise amplifier (LNA) may be used to amplify the NFC signal. Specifically, by amplifying the NFC signal through a low noise amplifier, the characteristics of the NFC signal in the I path and the Q path may be highlighted, and the noise introduced when the NFC signal is amplified may be reduced.

[0049] Specifically, the NFC signal can be separated in the frequency domain through orthogonal down-conversion, so that an I-channel digital signal and a Q-channel digital signal of the NFC signal can be obtained.

[0050] Optionally, before performing orthogonal down-conversion on the amplified NFC signal, the demodulation method further includes: performing filtering processing on the amplified NFC signal to suppress interference and noise of the NFC signal.

[0051] Specifically, before the amplified NFC signal is orthogonally down-converted, the NFC signal is filtered by a digital bandpass filter, which can suppress interference and noise of the NFC signal and ensure the accuracy of subsequent frequency division of the NFC signal into an I-channel digital signal and a Q-channel digital signal.

[0052] S202: The processor calculates a first signal-to-noise ratio and a first symbol value of an I-channel digital signal, and a second signal-to-noise ratio and a second symbol value of a Q-channel digital signal.

[0053] Specifically, by calculating the first signal-to-noise ratio and the first symbol value of the I-channel digital signal, and the second signal-to-noise ratio and the second symbol value of the Q-channel digital signal, the energy distribution of the NFC signal in the I-channel and the Q-channel can be analyzed and determined, and according to the energy distribution of the NFC signal, it can be determined which digital signal is demodulated to determine the transmission information more accurately. Therefore, it is necessary to calculate the signal-to-noise ratio and the symbol value of the I-channel digital signal and the Q-channel digital signal.

[0054] S203: The processor determines a target channel signal among the I-channel digital signal, the Q-channel digital signal, and a combined signal of the I-channel and Q-channel digital signals according to the first signal-to-noise ratio, the second signal-to-noise ratio, the first symbol value, and the second symbol value.

[0055] Specifically, according to the first signal-to-noise ratio, the second signal-to-noise ratio, the first symbol value, and the second symbol value, the distribution of the energy of the NFC signal in the I channel and the Q channel can be analyzed and determined. Therefore, based on the first signal-to-noise ratio, the second signal-to-noise ratio, the first symbol value, and the second symbol value, the processor can filter out the target channel signal from the I channel digital signal, the Q channel digital signal, and the combined channel signal of the I channel and Q channel digital signals.

[0056] S204: The processor demodulates the target path signal to determine the information transmitted by the NFC signal.

[0057] Specifically, the Fourier algorithm can be used for demodulation, and the sine sequence and cosine sequence are used as orthogonal reference signals to perform operations with the discrete sampling values ​​of the target signal to obtain the required real and imaginary information, and then the real and imaginary information are restored to the original digital data to determine the information transmitted by the NFC signal.

[0058] In the embodiment of the present disclosure, after the received NFC signal is processed into an I-channel digital signal and a Q-channel digital signal, the first signal-to-noise ratio and the first symbol value of the I-channel digital signal, as well as the second signal-to-noise ratio and the second symbol value of the Q-channel digital signal are first calculated respectively. Then, based on the first signal-to-noise ratio, the second signal-to-noise ratio, the first symbol value and the second symbol value, the target channel signal that is most suitable for demodulation among the I-channel digital signal, the Q-channel digital signal and the combined signal of the I-channel and Q-channel digital signals is determined. Finally, the target channel signal is demodulated to determine the information transmitted by the NFC signal. In this way, a digital signal with concentrated energy or a combined signal of two digital signals can be automatically selected for demodulation. Therefore, the embodiment of the present disclosure can improve the accuracy of demodulating information transmitted by the NFC signal.

[0059] The present disclosure provides another demodulation method for NFC signals. Figure 3 As shown, the demodulation method includes:

[0060] S301: The processor receives an NFC signal and pre-processes the NFC signal to obtain an I-channel digital signal and a Q-channel digital signal of the NFC signal.

[0061] S302: The processor calculates a first signal-to-noise ratio and a first symbol value of an I-channel digital signal, and a second signal-to-noise ratio and a second symbol value of a Q-channel digital signal.

[0062] S303: When the difference between the first signal-to-noise ratio and the second signal-to-noise ratio is greater than a set threshold, the processor uses the I-channel digital signal as the target channel signal.

[0063] Specifically, if the difference between the first signal-to-noise ratio and the second signal-to-noise ratio is greater than the set threshold, it indicates that the energy concentrated on the I path of the NFC signal is much higher than the energy concentrated on the Q path. In this case, the information transmitted by the NFC signal can be more accurately obtained by demodulating the I-path digital signal. Therefore, in the above case, the processor needs to use the I-path digital signal as the target path signal.

[0064] S304: When the difference between the second signal-to-noise ratio and the first signal-to-noise ratio is greater than a set threshold, the processor uses the Q-channel digital signal as the target channel signal.

[0065] Specifically, if the difference between the second signal-to-noise ratio and the first signal-to-noise ratio is greater than the set threshold, it indicates that the energy concentrated on the Q path of the NFC signal is much higher than the energy concentrated on the I path. In this case, the information transmitted by the NFC signal can be more accurately obtained by demodulating the Q path digital signal. Therefore, in the above case, the processor needs to use the Q path digital signal as the target path signal.

[0066] S305, when the absolute value of the difference between the first signal-to-noise ratio and the second signal-to-noise ratio is less than or equal to a set threshold, the processor determines a target channel signal among the I-channel digital signal, the Q-channel digital signal, and the combined signal of the I-channel and Q-channel digital signals according to the first symbol value and the second symbol value.

[0067] Specifically, if the absolute value of the difference between the first signal-to-noise ratio and the second signal-to-noise ratio is less than or equal to the set threshold, it indicates that the energy of the NFC signal distributed on the I and Q paths is relatively balanced, or the difference is small. Therefore, it is necessary to further determine which digital signal of the I digital signal, the Q digital signal, and the combined signal of the I and Q digital signals to demodulate based on the first symbol value and the second symbol value, so as to more accurately obtain the information transmitted by the NFC signal.

[0068] Optionally, determining a target path signal among an I-path digital signal, a Q-path digital signal, and a combined signal of the I-path and Q-path digital signals according to the first symbol value and the second symbol value includes: when the number of corresponding point symbols in the first symbol value and the second symbol value that are identical or opposite is greater than or equal to a set number, using the combined signal of the I-path and Q-path digital signals as the target path signal; when the number of corresponding point symbols in the first symbol value and the second symbol value that are identical or opposite is less than a set number, if the first signal-to-noise ratio is greater than the second signal-to-noise ratio, using the I-path digital signal as the target path signal; if the first signal-to-noise ratio is less than or equal to the second signal-to-noise ratio, using the Q-path digital signal as the target path signal.

[0069] Specifically, the first symbol value includes a set of symbols of I-channel related values ​​corresponding to multiple zero-crossing points, and the second symbol value includes a set of symbols of Q-channel related values ​​corresponding to multiple zero-crossing points. If the number of corresponding points in the first symbol value and the second symbol value (corresponding points are zero-crossing points corresponding to the first symbol value and the second symbol value) with the same or opposite symbols is greater than or equal to the set number, it indicates that the energy of the NFC signal is relatively balanced in the I channel and the Q channel. Therefore, in this case, it is necessary to use the combined signal of the I channel and Q channel digital signals as the target channel signal.

[0070] Specifically, if the number of corresponding points in the first symbol value and the second symbol value that have the same or opposite symbols is less than the set number, it indicates that the energy distribution of the NFC signal on the I path and the Q path is slightly different. Therefore, it is necessary to further compare the magnitude relationship between the signal-to-noise ratios of the I path and the Q path to determine whether the energy of the NFC signal is more concentrated on the I path or the Q path.

[0071] Specifically, if the first signal-to-noise ratio is greater than the second signal-to-noise ratio, it indicates that the energy of the NFC signal is more concentrated on the I path. Therefore, it is necessary to use the I path digital signal as the target path signal. If the first signal-to-noise ratio is less than or equal to the second signal-to-noise ratio, it indicates that the energy of the NFC signal is more concentrated on the Q path. Therefore, it is necessary to use the Q path digital signal as the target path signal.

[0072] Optionally, when the number of corresponding point symbols in the first symbol value and the second symbol value that are the same is greater than or equal to a set number, the following expression is used to calculate the combined signal of the I-channel and Q-channel digital signals:

[0073]

[0074] When the number of corresponding points with opposite signs in the first symbol value and the second symbol value is greater than or equal to the set number, the combined signal of the I-channel and Q-channel digital signals is calculated using the following expression:

[0075]

[0076] Among them, Cadp(n) is the combined signal of the I-channel and Q-channel digital signals, CI(n) is the I-channel digital signal, and CQ(n) is the Q-channel digital signal.

[0077] S306: The processor demodulates the target path signal to determine the information transmitted by the NFC signal.

[0078] In the embodiment of the present disclosure, by comparing the difference between the first signal-to-noise ratio and the second signal-to-noise ratio, the difference between the second signal-to-noise ratio and the first signal-to-noise ratio and the set threshold, it is determined whether the energy of the NFC signal is more distributed in the I path or the Q path. And when the energy of the NFC signal distributed in the I path and the Q path is relatively balanced, or the difference is small, the energy distribution of the NFC signal is further judged based on the first symbol value and the second symbol value. In this way, the accuracy of the determined target path signal is guaranteed, and then the accuracy of the information transmitted by the subsequently demodulated NFC signal is guaranteed.

[0079] The present disclosure provides another demodulation method for NFC signals. Figure 4 As shown, the demodulation method includes:

[0080] S401: The processor receives an NFC signal and pre-processes the NFC signal to obtain an I-channel digital signal and a Q-channel digital signal of the NFC signal.

[0081] S402: The processor calculates a first correlation value of an I-channel digital signal and a second correlation value of a Q-channel digital signal.

[0082] Specifically, the first correlation value and the second correlation value may be calculated respectively according to the subcarrier characteristics of the I-channel digital signal and the Q-channel digital signal.

[0083] Exemplarily, taking the subcarrier characteristic frequency as 848KHz, the sampling period as 6.78MHz, and the reference signal as ref=[-1-1-1-1 1 1 1 1], the first correlation value can be calculated according to the following expression (1), and the second correlation value can be calculated according to the following expression (2).

[0084] CI(n)=sum(I(n,…,n+7).*ref), expression (1);

[0085] CQ(n)=sum(Q(n,…,n+7).*ref), expression (2);

[0086] Among them, CI(n) is the I-channel digital signal, CQ(n) is the Q-channel digital signal, sum() is the summation operation; and “.*” is the multiplication operation of corresponding points in two vectors.

[0087] S403: The processor calculates a first power value and a first symbol value of the I path according to the first correlation value, and calculates a second power value and a second symbol value of the Q path according to the second correlation value.

[0088] Specifically, the power value is a parameter reflecting the strength of the signal, which is determined by calculating the square of the correlation value. The sign value is a parameter reflecting the phase information of the signal, which is determined by taking the sign of the correlation value.

[0089] Specifically, when calculating the power value and the symbol value of the I-channel digital signal and the Q-channel digital signal, it is necessary to search the frame header synchronization area.

[0090] For each valid half-subcarrier searched, if it is a positive half-subcarrier, for any zero-crossing point, the first power value is calculated according to the following expression (3), the second power value is calculated according to the following expression (4), the first correlation value is calculated according to the following expression (5), and the second correlation value is calculated according to the following expression (6):

[0091] I PwrI0 =CI0 2 , expression (3);

[0092] I PwrQ0 =CQ(PosI0) 2 , expression (4);

[0093] I SI0 =sign(CI0), expression (5);

[0094] I SQ0=sign(CQ(PosI0)), expression (6);

[0095] Among them, I PwrI0 is the first power value, CI is the first correlation value, CQ is the second correlation value, CI0 represents the positive maximum value of the first correlation value, PosI0 is the position of the positive maximum value, I PwrQ0 is the second power value, I SI0 is the first symbol value, I SQ0 is the second sign value, and sign is the sign function.

[0096] For each valid half-subcarrier searched, if it is a negative half-subcarrier, for any zero-crossing point, the first power value is calculated according to the following expression (7), the second power value is calculated according to the following expression (8), the first correlation value is calculated according to the following expression (9), and the second correlation value is calculated according to the following expression (10):

[0097] I PwrI1 =CI1 2 , expression (7);

[0098] I PwrQ1 =CQ(PosI1) 2 , expression (8);

[0099] I SI1 =sign(CI1), expression (9);

[0100] I SQ1 =sign(CQ(PosI1)), expression (10);

[0101] Among them, I PwrI1 is the first power value, CI is the first correlation value, CQ is the second correlation value, CI1 is the positive minimum value of the first correlation value, PosI1 is the position of the positive maximum value, I PwrQ1 is the second power value, I SI1 is the first symbol value, I SQ1 is the second sign value, and sign is the sign function.

[0102] Specifically, since both the I-channel digital signal and the Q-channel digital signal include multiple zero-crossing points, the first power value can be expressed according to the following expression (11), the second power value can be expressed according to the following expression (12), the first correlation value can be expressed according to the following expression (13), and the second correlation value can be expressed according to the following expression (14):

[0103] I PwrI =[I PwrI0 , I PwrI1 ,…I PwrI2M-1 ], expression (11);

[0104] I PwrQ =[I PwrQ0 , I PwrQ1 ,…I PwrQ2M-1 ], expression (12);

[0105] I SI =[I SI0 , I SI1 ,…I SI2M-1 ], expression (13);

[0106] I SQ =[I SQ0 , I SQ1 ,…I SQ2M-1 ], expression (14);

[0107] S404: The processor calculates a first signal-to-noise ratio of the I path according to the first power value, and calculates a second signal-to-noise ratio of the Q path according to the second power value.

[0108] Specifically, the first signal-to-noise ratio of the I path is calculated according to the following expression (15) based on the first power value, and the second signal-to-noise ratio of the Q path is calculated according to the following expression (16) based on the second power value.

[0109]

[0110] Among them, SNR I is the first signal-to-noise ratio, SNR Q is the second signal-to-noise ratio, M and N are integers, I and Q are index variables, and their values ​​range from 0 to 2M-1.

[0111] S405: The processor determines a target channel signal among the I-channel digital signal, the Q-channel digital signal, and a combined signal of the I-channel and Q-channel digital signals according to the first signal-to-noise ratio, the second signal-to-noise ratio, the first symbol value, and the second symbol value.

[0112] S406: The processor demodulates the target path signal to determine the information transmitted by the NFC signal.

[0113] In the embodiment of the present disclosure, when calculating the first signal-to-noise ratio, the second signal-to-noise ratio, the first symbol value, and the second symbol value, the correlation value and the power value of the I-path and Q-path digital signals are first calculated, and then the signal-to-noise ratio and the symbol value of the I-path and Q-path digital signals are calculated according to the correlation value and the power value. In this way, the accuracy of the calculated signal-to-noise ratio and the symbol value of the I-path and Q-path digital signals is improved.

[0114] Combination Figure 5As shown, the embodiment of the present disclosure provides a demodulation device 500 for NFC signals, including: a processing module 501, a calculation module 502, a determination module 503 and a demodulation module 504. The processing module 501 is configured to receive an NFC signal and pre-process the NFC signal to obtain an I-channel digital signal and a Q-channel digital signal of the NFC signal. The calculation module 502 is configured to calculate a first signal-to-noise ratio and a first symbol value of the I-channel digital signal, and a second signal-to-noise ratio and a second symbol value of the Q-channel digital signal. The determination module 503 is configured to determine the target channel signal in the I-channel digital signal, the Q-channel digital signal and the combined signal of the I-channel and Q-channel digital signals according to the first signal-to-noise ratio, the second signal-to-noise ratio, the first symbol value and the second symbol value. The demodulation module 504 is configured to demodulate the target channel signal and determine the information transmitted by the NFC signal.

[0115] Combination Figure 6 As shown, the embodiment of the present disclosure provides a demodulation device 600 for NFC signals, and the demodulation device 600 for NFC signals includes: a processor (processor) 601 and a memory (memory) 602. Optionally, the device may also include a communication interface (Communication Interface) 603 and a bus 604. Among them, the processor 601, the communication interface 603, and the memory 602 can communicate with each other through the bus 604. The communication interface 603 can be used for information transmission. The processor 601 can call the logic instructions in the memory 602 to execute the demodulation method for NFC signals applied to the demodulation device 600 for NFC signals of the above embodiment.

[0116] In addition, the logic instructions in the memory 602 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.

[0117] The memory 602 is a computer-readable storage medium that can be used to store software programs and computer executable programs, such as program instructions / modules corresponding to the method in the embodiment of the present disclosure. The processor 601 executes the function application and data processing by running the program instructions / modules stored in the memory 602, that is, the demodulation method for NFC signals applied to the demodulation device 600 for NFC signals in the above embodiment is implemented.

[0118] The memory 602 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 602 may include a high-speed random access memory and may also include a non-volatile memory.

[0119] 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-mentioned demodulation method for NFC signals.

[0120] 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 causing 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, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a disk or an optical disk, and other media that can store program codes.

[0121] The above description and the 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 only possible changes. 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 claims. As used in the description of the embodiments and the claims, 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.

[0122] 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.

[0123] 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.

[0124] 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 demodulation method for NFC signals, characterized in that: include: Receive the NFC signal, and pre-process the NFC signal to obtain an I-channel digital signal and a Q-channel digital signal of the NFC signal; Calculating a first signal-to-noise ratio and a first symbol value of an I-channel digital signal, and a second signal-to-noise ratio and a second symbol value of a Q-channel digital signal; Determine a target channel signal among an I-channel digital signal, a Q-channel digital signal, and a combined signal of the I-channel and Q-channel digital signals according to the first signal-to-noise ratio, the second signal-to-noise ratio, the first symbol value, and the second symbol value; Demodulate the target signal to determine the information transmitted by the NFC signal.

2. The demodulation method according to claim 1, characterized in that: Determining a target channel signal in an I-channel digital signal, a Q-channel digital signal, and a combined channel signal of the I-channel and Q-channel digital signals according to the first signal-to-noise ratio, the second signal-to-noise ratio, the first symbol value, and the second symbol value, comprises: When the difference between the first signal-to-noise ratio and the second signal-to-noise ratio is greater than a set threshold, using the I-channel digital signal as the target channel signal; When the difference between the second signal-to-noise ratio and the first signal-to-noise ratio is greater than a set threshold, using the Q-channel digital signal as the target channel signal; When the absolute value of the difference between the first signal-to-noise ratio and the second signal-to-noise ratio is less than or equal to the set threshold, the target channel signal among the I-channel digital signal, the Q-channel digital signal and the combined signal of the I-channel and Q-channel digital signals is determined according to the first symbol value and the second symbol value.

3. The demodulation method according to claim 2, characterized in that: Determining a target channel signal in an I-channel digital signal, a Q-channel digital signal, and a combined channel signal of the I-channel and Q-channel digital signals according to a first symbol value and a second symbol value, comprising: When the number of corresponding points with the same or opposite signs in the first symbol value and the second symbol value is greater than or equal to the set number, a combined signal of the I-channel and Q-channel digital signals is used as the target channel signal; When the number of corresponding point symbols in the first symbol value and the second symbol value that are identical or opposite is less than a set number, if the first signal-to-noise ratio is greater than the second signal-to-noise ratio, the I-channel digital signal is used as the target channel signal; if the first signal-to-noise ratio is less than or equal to the second signal-to-noise ratio, the Q-channel digital signal is used as the target channel signal.

4. The demodulation method according to claim 3, characterized in that: When the number of corresponding point symbols in the first symbol value and the second symbol value that are the same is greater than or equal to the set number, the combined signal of the I-channel and Q-channel digital signals is calculated using the following expression: When the number of corresponding points with opposite signs in the first symbol value and the second symbol value is greater than or equal to the set number, the combined signal of the I-channel and Q-channel digital signals is calculated using the following expression: Among them, Cadp(n) is the combined signal of the I-channel and Q-channel digital signals, CI(n) is the I-channel digital signal, and CQ(n) is the Q-channel digital signal.

5. The demodulation method according to any one of claims 1 to 4, characterized in that: Calculating a first signal-to-noise ratio and a first symbol value of an I-channel digital signal, and a second signal-to-noise ratio and a second symbol value of a Q-channel digital signal, comprising: Calculate a first correlation value of an I-channel digital signal and a second correlation value of a Q-channel digital signal; Calculate a first power value and a first symbol value of the I path according to the first correlation value, and calculate a second power value and a second symbol value of the Q path according to the second correlation value; A first signal-to-noise ratio of the I path is calculated according to the first power value, and a second signal-to-noise ratio of the Q path is calculated according to the second power value.

6. The demodulation method according to any one of claims 1 to 4, characterized in that: Pre-process the NFC signal, including: Amplify the NFC signal; The amplified NFC signal is orthogonally down-converted to obtain an I-channel digital signal and a Q-channel digital signal.

7. The demodulation method according to claim 6, characterized in that: Before performing orthogonal down-conversion on the amplified NFC signal, the demodulation method further includes: The amplified NFC signal is filtered to suppress interference and noise of the NFC signal.

8. A demodulation device for NFC signals, characterized in that: include: A processing module is configured to receive an NFC signal and pre-process the NFC signal to obtain an I-channel digital signal and a Q-channel digital signal of the NFC signal; A calculation module is configured to calculate a first signal-to-noise ratio and a first symbol value of an I-channel digital signal, and a second signal-to-noise ratio and a second symbol value of a Q-channel digital signal; A determination module is configured to determine a target channel signal among an I-channel digital signal, a Q-channel digital signal, and a combined channel signal of the I-channel and Q-channel digital signals according to the first signal-to-noise ratio, the second signal-to-noise ratio, the first symbol value, and the second symbol value; The demodulation module is configured to demodulate the target path signal to determine the information transmitted by the NFC signal.

9. A demodulation device for NFC signals, comprising a processor and a memory storing program instructions, characterized in that: The processor is configured to execute the demodulation method for NFC signals according to any one of claims 1 to 7 when executing the program instructions.

10. An NFC device, characterized in that: include: Equipment body; The demodulation device for NFC signals as claimed in claim 8 or 9 is arranged on the device body.

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