Device for quantifying NFC receiving interference

Abstract

The invention discloses a device for quantifying NFC receiving interference. The device comprises an MCU end and a noise signal acquisition unit. The MCU end is used for realizing information acquisition and upper computer data transmission functions; the noise signal acquisition unit comprises a controller core NXP-PN5190, an RFID (Radio Frequency Identification Device) induction coil and a matching tuning unit; the controller core NXP-PN5190 is used for realizing receiving input partial voltage self-adaption, baseband gain configuration and ADC conversion, gain matched filtering and noise signal sampling; and the matching tuning unit is used for realizing resonance optimization between the RFID coil and the NXP-PN5190 so as to ensure that the device can transmit signals with the maximum efficiency and receive signals from the environment. According to the invention, the coupling coil is standardized, analog data processing and quantification are realized through the noise analysis function of the module, and finally the quantification and standardization of the test result are realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of RFID, and in particular relates to a device for quantifying NFC reception interference. Background Art

[0002] RFID technology is gaining popularity around the world, and RFID technology is currently the core function of card reader equipment in the transportation and financial payment industries. With the development of science and technology, products are moving towards miniaturization and compactness to enhance consumers' product experience. However, the compact development trend of products has brought major challenges to RFID design. Among these challenges, the impact of the liquid crystal environment on RFID performance is one of the key parts.

[0003] In the existing technical solutions, an oscilloscope device can be used for relevant tests. The oscilloscope detects the signal in the coil loop by connecting the probe and GND into a loop. The implementation principle of this solution is to sense the signal in the environment through the coupling of the coil. The liquid crystal will continuously refresh the display when working. During the refresh process, the driving source signal changes rapidly and radiates interference outward. This signal will be sensed by the detection coil of the oscilloscope and converted into a corresponding electrical signal. Therefore, the level of the electrical signal can be understood as the interference level of the liquid crystal's external radiation. Through this solution, the interference signal of the liquid crystal refresh can be obtained, and a preliminary judgment of the interference can be made. However, this solution has the following problems:

[0004] 1) The RFID receiving circuit has internal receiving amplification and filtering circuits, and the test signal cannot effectively evaluate the interference level processed inside the chip;

[0005] 2) The test results cannot be quantified, so it is impossible to establish effective judgment criteria. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides a device for quantifying NFC reception interference.

[0007] In order to achieve the above technical objectives, the technical solution adopted by the present invention is: a device for quantifying NFC reception interference, including an MCU end and a noise signal acquisition unit;

[0008] The MCU end is used to realize the functions of information collection and host computer data transmission;

[0009] The noise signal acquisition unit includes a controller core NXP-PN5190, an RFID induction coil and a matching tuning unit;

[0010] The controller core NXP-PN5190 is used to implement receiving input voltage adaptation, baseband gain configuration and ADC conversion, gain matching filtering and noise signal sampling;

[0011] The matching tuning unit is used to optimize the resonance between the RFID coil and the NXP-PN5190 to ensure that the device can transmit signals with maximum efficiency and receive signals from the environment.

[0012] As a possible implementation mode, further, the receiving input voltage division adaptation is specifically as follows: after the differential signal inputted from the antenna end is inputted into the chip, the amplitude value of the input signal is controlled within the effective receiving range through the internal adjustable resistor.

[0013] As a possible implementation, further, the RSSI_Value is controlled to be around 0x40 by matching the receiving feedback resistor.

[0014] As a possible implementation mode, further, the baseband gain configuration and ADC conversion are specifically as follows: the differential signal input from the antenna end is amplified by a baseband gain amplifier with an amplification range of -6Db to 24Db, and then converted into a digital signal by an ADC.

[0015] As a possible implementation, further, the gain matching filtering is specifically: performing final gain control on the signal through a matching filter, and performing 4-level amplification control on the signal in this stage.

[0016] As a possible implementation, further, the noise signal sampling is specifically as follows: after the signal amplification process, when no card is placed on the coil, the amplitude of the background noise signal is obtained by ADC sampling; by placing the coil above the liquid crystal, the corresponding liquid crystal loading noise can be obtained.

[0017] As a possible implementation, further, the RFID induction coil uses a 45mm*45mm antenna; for the detection of other noises, a small coil is used for interference collection.

[0018] As a possible implementation manner, further, the matching tuning unit includes a front-stage filtering circuit, a rear-stage matching circuit, and a resistor connected in series with the rear-stage matching circuit;

[0019] The pre-stage filter circuit is used to process the 13.56Mhz approximate square wave signal output by the radio frequency chip into a 13.56Mhz sine wave signal;

[0020] The post-stage matching circuit realizes the resonant matching between the filter output and the antenna through an L-type matching circuit;

[0021] Finally, the antenna Q value is controlled by a series resistor to adjust the transmission signal strength.

[0022] As a possible implementation method, further, the host computer data transmission function is used to organize the data and realize the data graphing. The overall distribution of the noise level of the signal after the graphing process can be intuitively obtained in the graph; at the same time, the collected data is statistically processed, and the maximum value and effective value of the noise signal are statistically analyzed and then output.

[0023] As a possible implementation mode, further, the information collection function has multiple detection modes;

[0024] The MCU needs to implement the functions of the corresponding channels and provide functional interfaces to obtain signals on related acquisition links and realize data visualization.

[0025] By adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0026] The present invention improves the accuracy of RFID noise detection, and the data can be quantified through ADC sampling; the consistency of the acquisition environment can be ensured through standardized test coils; the noise signal is collected from the inside of the RF front end, so that the acquired noise signal meets the signal expectations of the RFID; in addition, the test results of the present invention are quantified through internal ADC sampling, so that the output results have reference value. In addition, the device can not only be used to troubleshoot liquid crystal interference, but also can be used to verify other interference sources. By using different antenna coils, the acquisition target can be switched. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 This is the receiving logic diagram of the NXP-PN5190 RF front-end chip;

[0029] Figure 2 The circuit schematic diagram of the matching tuning unit;

[0030] Figure 3 is a circuit diagram of a pre-stage filter circuit;

[0031] Figure 4 is a circuit diagram of an L-type matching circuit;

[0032] Figure 5 It is a graphical diagram of the data;

[0033] Figure 6Schematic diagram of data visualization. DETAILED DESCRIPTION

[0034] The present invention will be further described in detail below in conjunction with the accompanying drawings and examples. It is particularly noted that the following examples are only used to illustrate the present invention, but are not intended to limit the scope of the present invention. Similarly, the following examples are only partial embodiments of the present invention rather than all embodiments, and all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present invention.

[0035] This embodiment provides a device for quantifying NFC receiving interference, which mainly consists of an MCU end (MCU controller) and a noise signal acquisition unit;

[0036] The core of the hardware function lies in the design of the noise signal acquisition unit, which mainly consists of the following three parts:

[0037] 1) Controller core NXP-PN5190

[0038] The receiving logic of the NXP-PN5190 RF front-end chip is shown in the attached figure. Figure 1 As shown, the controller core NXP-PN5190 is mainly used to realize receiving input voltage adaptation, baseband gain configuration and ADC conversion, gain matching filtering and noise signal sampling;

[0039] a) Receive input voltage adaptation

[0040] As attached Figure 1 As shown in the figure, RXN / RXP is a set of differential signals input from the antenna end. After the differential signals input from the antenna end are input into the chip, the input signal amplitude value is controlled within the effective receiving range through the internal adjustable resistor. The receiving feedback resistor needs to be matched to control the RSSI_Value to be around 0x40.

[0041] b) Baseband gain configuration and ADC conversion

[0042] The input signal on RXN / RXP is amplified by a baseband gain amplifier (Base Band Amplifier) ​​with a range of -6Db to 24Db, and then converted into a digital signal by an ADC.

[0043] c) Gain Matched Filter

[0044] The matching filter can perform the final gain control on the signal. In this stage, the signal is amplified in 4 levels, which needs to be adjusted according to the reception situation.

[0045] d) Noise signal sampling

[0046] After the above signal amplification process, when there is no card placed on the coil, the amplitude of the background noise signal is obtained through ADC sampling. By placing the coil above the liquid crystal, the corresponding liquid crystal loading noise can be obtained.

[0047] 2) RFID induction coil

[0048] The purpose of the device design is to sample and analyze the environment of the RFID antenna coil. Based on the test requirements of EMV Co Contactless L1, the antenna design needs to meet the size requirement of more than 45mm*45mm. Therefore, the design of the device needs to use a 45mm*45mm antenna. In addition, for the detection of other noises, a small coil is required for interference collection.

[0049] 3) Matching tuning unit

[0050] The matching tuning unit includes a front-stage filtering circuit, a rear-stage matching circuit, and a resistor connected in series with the rear-stage matching circuit. The corresponding circuit schematic is shown in the attached figure. Figure 2 shown.

[0051] After the RFID coil is designed, it is necessary to optimize the resonance between the RFID coil and the NXP-PN5190 through the pre-stage filtering circuit and the post-stage L-type matching circuit to ensure that the device can transmit signals with maximum efficiency and receive signals from the environment.

[0052] Pre-filter circuit (such as attached Figure 3 The output of the RF chip is a 13.56Mhz approximate square wave signal. In addition to the 13.56Mhz baseband signal, the signal also contains high-order harmonics. The signal is processed into a 13.56Mhz sine wave signal through an LC low-pass filter circuit.

[0053] Post-stage matching circuit (such as attached Figure 4 As shown): The post-matching circuit achieves resonant matching between the filter output and the antenna through an L-type matching circuit.

[0054] Finally, the antenna Q value is controlled by a series resistor to adjust the transmission signal strength.

[0055] The MCU is mainly responsible for the realization of logic control functions, which is used to realize information collection and host computer data transmission functions;

[0056] A) Data transmission from host computer

[0057] The data collected by the acquisition device is not intuitive. The data collected from the channel needs to be processed and transmitted to the host computer, which needs to organize the data and realize the data graphics (such as the attached Figure 5 shown).

[0058] After the signal is processed graphically, the overall distribution of the noise level can be obtained intuitively in the graph. Since the signal noise is unstable, it is necessary to perform statistical processing on the collected data, and then output the maximum value and effective value of the noise signal after statistics.

[0059] B) Information collection function

[0060] The information collection unit has multiple detection methods, as follows:

[0061]

[0062] The MCU needs to implement the functions of the corresponding channels and provide functional interfaces to obtain signals on the relevant acquisition links and realize data visualization (such as the attached Figure 6 shown).

[0063] In summary, the present invention standardizes the coupling coil and realizes analog data processing and quantification through the noise analysis function (CTS) of the module, thereby finally achieving quantification and standardization of the test results.

[0064] The above descriptions are only some embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any equivalent device or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A device for quantifying NFC reception interference, characterized in that: Including MCU end and noise signal acquisition unit; The MCU end is used to realize the functions of information collection and host computer data transmission; The noise signal acquisition unit includes a controller core NXP-PN5190, an RFID induction coil and a matching tuning unit; The controller core NXP-PN5190 is used to implement receiving input voltage adaptation, baseband gain configuration and ADC conversion, gain matching filtering and noise signal sampling; The matching tuning unit is used to optimize the resonance between the RFID coil and the NXP-PN5190 to ensure that the device can transmit signals with maximum efficiency and receive signals from the environment.

2. The device for quantifying NFC reception interference according to claim 1, characterized in that: The receiving input voltage division adaptation is specifically as follows: after the differential signal input from the antenna end is input into the chip, the input signal amplitude value is controlled within the effective receiving range through the internal adjustable resistor.

3. The device for quantifying NFC reception interference according to claim 2, characterized in that: By matching the receiving feedback resistor, the RSSI_Value is controlled to be around 0x40.

4. The device for quantifying NFC reception interference according to claim 1, characterized in that: The baseband gain configuration and ADC conversion are specifically as follows: the differential signal input from the antenna end is amplified by a baseband gain amplifier, with an amplification range of -6Db to 24Db, and then converted into a digital signal by an ADC.

5. The device for quantifying NFC reception interference according to claim 1, characterized in that: The gain matching filtering specifically includes: performing final gain control on the signal through a matching filter, and performing 4-level amplification control on the signal in this stage.

6. The device for quantifying NFC reception interference according to claim 1, characterized in that: The noise signal sampling is specifically as follows: after the signal amplification process, when no card is placed on the coil, the amplitude of the background noise signal is obtained by ADC sampling; by placing the coil above the liquid crystal, the corresponding liquid crystal loading noise can be obtained.

7. The device for quantifying NFC reception interference according to claim 1, characterized in that: The RFID induction coil uses a 45mm*45mm antenna; for the detection of other noises, a small coil is used for interference collection.

8. The device for quantifying NFC reception interference according to claim 1, characterized in that: The matching and tuning unit includes a front-stage filtering circuit, a rear-stage matching circuit, and a resistor connected in series with the rear-stage matching circuit; The pre-stage filter circuit is used to process the 13.56Mhz approximate square wave signal output by the radio frequency chip into a 13.56Mhz sine wave signal; The post-stage matching circuit realizes the resonant matching between the filter output and the antenna through an L-type matching circuit; Finally, the antenna Q value is controlled by a series resistor to adjust the transmission signal strength.

9. The device for quantifying NFC reception interference according to claim 1, characterized in that: The host computer data transmission function is used to organize the data and realize the graphing of the data. The overall distribution of the noise level of the signal after the graphing can be intuitively obtained in the graph; at the same time, the collected data is statistically processed, and the maximum value and effective value of the noise signal are statistically analyzed and then output.

10. The device for quantifying NFC reception interference according to claim 1, characterized in that: The information collection function has multiple detection modes; The MCU needs to implement the functions of the corresponding channels and provide functional interfaces to obtain signals on related acquisition links and realize data visualization.

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