Radio frequency card reader, state switching method for radio frequency card reader and electronic equipment
By adding a modulation signal and performing baseband processing in the RF card reader, the problem of low detection accuracy in low-power card detection schemes in scenarios with small tags or weakly coupled tags is solved, achieving high sensitivity and low power consumption detection effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- BEIJING CEC HUADA ELECTRONIC DESIGN CO LTD
- Filing Date
- 2025-11-20
- Publication Date
- 2026-04-28
AI Technical Summary
Existing low-power card detection solutions have low detection accuracy in scenarios with small tags or weakly coupled tags.
Adding a modulation signal to the RF card reader and setting up a baseband processing unit to perform matched filtering, smoothing filtering, and other processing on the received sensing signal improves the accuracy of peak measurement values.
It improves the detection accuracy of small or weakly coupled tags, avoids missed detections and false detections, and reduces power consumption.
Smart Images
Figure CN121936484A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of communication technology, specifically to an RFID card reader, a state switching method for the RFID card reader, and an electronic device. Background Technology
[0002] Radio frequency (RF) communication devices have a wide range of applications. Common examples of RF communication devices include Near Field Communication (NFC) devices and Radio Frequency Identification (RFID) devices. Typical NFC or RFID systems include reader devices and card devices. A reader device, also known as a card reader, poller, interrogator, or proximity coupling device (PCD), is referred to directly as a card reader in this application. The card reader generates a high-frequency radio field, polls, and attempts to communicate with a passive or active communication counterpart. The communication counterpart, i.e., the card device (also called a tag, card, or card device), can specifically be a passive transponder or active card emulation device acting as a proximity integrated circuit card (PICC), or other smart devices such as mobile phones that can be used as card devices.
[0003] Generally, card readers typically activate their RF field and continuously poll for communication counterparts across various communication technologies (e.g., NFC-A, NFC-B, NFC-F, NFC-V) to detect them. However, communication counterparts and the card reader are not always communicating, which is too power-intensive for battery-powered devices (e.g., mobile devices, wearables, door lock readers), quickly depleting the battery and reducing device availability. Therefore, Low Power Card Detection (LPCD), also known as Low Power Device Detection (LPDD), can be used to reduce card reader power consumption. This LPCD technology uses short RF sensing pulses (or short radio frequency pulses, detection signals) to detect load changes at the card reader's RF interface to determine the presence of a communication counterpart, thus waking up the polling process and extending battery life. This technology allows the card reader to significantly shorten its RF field activation time and switch to a power-saving state (such as standby mode) between sensing pulses.
[0004] However, low-power card detection schemes in related technologies have low detection accuracy in scenarios with small tags or weakly coupled tags. Summary of the Invention
[0005] This invention provides an RFID card reader, a state switching method for the RFID card reader, and an electronic device to solve the problem of low accuracy in low-power card detection schemes in related technologies, especially in scenarios with small tags or weakly coupled tags.
[0006] In a first aspect, the present invention provides an RFID card reader, which includes at least: a communication control module, a transmitting module, and a receiving module; The transmitting module is used to transmit a sensing signal with a modulated signal; The receiving module includes a front-end processing unit and a baseband processing unit; The front-end processing unit is used to process the received sensing signal to obtain the corresponding in-phase component signal and quadrature component signal; The baseband processing unit includes a matched filtering subunit, a channel selection subunit or a channel combining subunit, a smoothing filtering subunit, and a peak search subunit connected in sequence. The baseband processing unit is used to process the in-phase component signal and / or the quadrature component signal output by the front-end processing unit to obtain a target peak measurement value. The target peak measurement value includes the peak measurement value of the modulation signal. The communication control module is used to control the entry into a polling state based on the target peak measurement value.
[0007] In one optional implementation, the front-end processing unit includes at least a mixing subunit, a filtering subunit, and an amplification subunit connected in sequence. The front-end processing unit further includes a gain control subunit, which adjusts the gain of the amplification subunit based on the signal output by the amplification subunit.
[0008] In one alternative implementation, the gain control subunit adjusts the gain of the amplification subunit based on the signal output by the amplification subunit and the radio frequency field strength of the sensing signal received by the front-end processing unit.
[0009] In one optional implementation, the front-end processing unit further includes a radio frequency attenuator for adjusting the radio frequency field strength of the sensing signal received by the front-end processing unit. The gain control subunit adjusts the gain of the amplification subunit based on the signal output by the amplification subunit and the RF field strength adjusted by the RF attenuator.
[0010] In one optional implementation, the sensing signal includes a modulation signal and a carrier signal; the sensing signal satisfies at least one of the following conditions: The modulation signal is located in the middle of the carrier signal; The duty cycle of the modulation signal is between 20% and 80%. The frequency of the carrier signal is fc, and the value of fc ranges from 10 to 18 MHz; The baseband frequency of the modulation signal is fc / 8 or fc / 16; The modulation depth of the modulated signal is between 1% and 95%. The total duration of the sensed signal is less than 40 microseconds; The duration of the modulation signal is between 5 microseconds and 30 microseconds.
[0011] In a second aspect, the present invention provides a state switching method for an RFID card reader, applicable to an RFID card reader according to the first aspect above or any corresponding embodiment thereof, the method comprising: The transmitting module transmits a sensing signal with modulation. The front-end processing unit in the receiving module processes the received sensing signal to obtain the corresponding in-phase component signal and quadrature component signal; The baseband processing unit in the receiving module performs matched filtering on the in-phase component signal and the quadrature component signal respectively to obtain a first signal and a second signal. It selects at least one of the first signal and the second signal for smoothing filtering and peak detection to obtain the target peak measurement value, or it combines the first signal and the second signal and then performs smoothing filtering and peak detection to obtain the target peak measurement value. The communication control module controls the entry into a polling state based on the target peak measurement value.
[0012] In one optional implementation, the front-end processing unit in the receiving module processes the received sensing signal to obtain corresponding in-phase component signals and quadrature component signals, including: The front-end processing unit performs mixing, filtering, and amplification processing on the sensed signal in two separate paths to obtain the in-phase component signal and the quadrature component signal.
[0013] In one optional implementation, the sensing signal includes a modulation signal and a carrier signal; the sensing signal satisfies at least one of the following conditions: The modulation signal is located in the middle of the carrier signal; The duty cycle of the modulation signal is between 20% and 80%. The frequency of the carrier signal is fc, and the value of fc ranges from 10 to 18 MHz; The baseband frequency of the modulation signal is fc / 8 or fc / 16; The modulation depth of the modulated signal is between 1% and 95%. The total duration of the sensed signal is less than 40 microseconds; The duration of the modulation signal is between 5 microseconds and 30 microseconds.
[0014] In one optional implementation, the baseband processing unit selects the first signal and the second signal, and performs smoothing filtering and peak detection on the first signal and the second signal respectively to obtain two target peak measurement values. When one of the target peak measurement values is greater than a first preset threshold, the communication control module controls the system to enter a polling state. or, The baseband processing unit selects the first signal and the second signal, and performs maximum ratio merging on the first signal and the second signal respectively. The merged signal is then smoothed, filtered, and peak detected to obtain the target peak measurement value. When the target peak measurement value is greater than a second preset threshold, the communication control module controls the system to enter a polling state.
[0015] Thirdly, the present invention provides an electronic device, comprising: an RFID card reader according to the first aspect above or any corresponding embodiment thereof.
[0016] The RFID reader, state switching method for the RFID reader, and electronic device provided in this invention add a modulation signal to the sensing signal used for card detection and set up a baseband processing unit to perform a series of processes such as matched filtering and smoothing filtering on the in-phase component signal and / or the quadrature component signal, or the combined signal of the two, of the received sensing signal. This avoids the influence of noise and interference, improves the accuracy of peak measurement values, and makes the RFID reader suitable for scenarios that require detection of small tags or weakly coupled tags. Specifically, a lower threshold can be set to improve the sensitivity of card detection and avoid missed detections. Since the influence of noise and interference is avoided, false detections will not occur, ensuring the accuracy of card detection. This not only ensures timely RFID communication response but also minimizes power consumption (false detections will lead to false wake-up of the RFID reader's polling, which will increase power consumption). Attached Figure Description
[0017] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0018] Figure 1 This is a schematic block diagram of a first structure of an RFID card reader according to an embodiment of the present invention; Figure 2This is a schematic diagram of a receiving module according to an embodiment of the present invention; Figure 3 This is a schematic diagram of a radio frequency communication system according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the signal timing of radio frequency communication according to an embodiment of the present invention; Figure 5 This is a schematic diagram of a sensing signal received by a receiving module according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the sensing signals before and during baseband processing according to an embodiment of the present invention; Figure 7 This is a schematic diagram of sensing signals before and during baseband processing according to another embodiment of the present invention; Figure 8 This is a schematic diagram of the design of a first modulation signal according to an embodiment of the present invention; Figure 9 This is a schematic diagram of the design of a second modulation signal according to an embodiment of the present invention; Figure 10 This is a schematic diagram of the design of a third modulation signal according to an embodiment of the present invention; Figure 11 This is a schematic diagram of the design of a fourth modulation signal according to an embodiment of the present invention; Figure 12 This is a schematic diagram of a sensing signal design according to an embodiment of the present invention; Figure 13 This is a flowchart illustrating a state switching method for an RFID card reader according to an embodiment of the present invention. Figure 14 This is a schematic diagram of the hardware structure of an electronic device according to an embodiment of the present invention. Detailed Implementation
[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0020] It is understood that before using the technical solutions disclosed in the various embodiments of the present invention, users should be informed of the types, scope of use, and usage scenarios of the personal information involved in the present invention and their authorization should be obtained in accordance with relevant laws and regulations through appropriate means.
[0021] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.
[0022] Low-power card detection technology detects nearby communication counterparts and only wakes up the card reader's polling function (specifically, it wakes up the relevant components of the card reader (the components that send polling commands to the detected communication counterparts)) when a nearby communication counterpart is detected. By applying low-power card detection technology, timely RF communication responses can be achieved without consuming a large amount of power.
[0023] As some smart devices become smaller, antenna sizes are also decreasing. Whether it's active RFID / NFC tags (tags powered by batteries) or passive tags (tags powered only by field power), the antenna size should be appropriately set to achieve a satisfactory user experience.
[0024] When the card reader performs LPCD card detection, the small size of the antenna makes the coupling between the card reader and the card weak. Moreover, the communication environment is affected by factors such as noise, interference and temperature. If the card reader has low sensitivity for low-power card detection, small tags or weakly coupled tags may be missed. If a high sensitivity is set (low detection threshold), polling may be easily triggered erroneously, increasing power consumption.
[0025] This embodiment provides an RFID card reader, such as... Figure 1 As shown, it includes at least: a communication control module 101, a transmitting module 102, and a receiving module 103; The transmitting module 102 is used to transmit a sensing signal with a modulated signal; specifically, the sensing signal can be transmitted under the control of the communication control module 101, and the transmitting module 102 generates the required sensing signal according to the configuration under the control of the communication control module. like Figure 2 As shown, the receiving module 103 includes a front-end processing unit 1031 and a baseband processing unit 1032; The front-end processing unit 1031 is used to process the received sensing signal to obtain the corresponding in-phase (I) component signal and quadrature (Q) component signal. like Figure 2As shown, the baseband processing unit 1032 includes a matched filtering subunit 10321, a channel selection subunit 10322 or a channel combining subunit, a smoothing filtering subunit 10323, and a peak search subunit 10324 connected in sequence. The baseband processing unit is used to process the in-phase component signal and / or the quadrature component signal output by the front-end processing unit to obtain a target peak measurement value. The target peak measurement value includes the peak measurement value of the modulated signal. The communication control module is used to control the entry into a polling state based on the target peak measurement value. Specifically, it enters the polling state by switching from the card detection state.
[0026] In this embodiment, the receiving module 103 is used to measure the received strength of the sensing signal, that is, to detect the peak value of the received sensing signal.
[0027] The matched filtering can be designed based on the preset envelope shape of the sensing signal. For the in-phase component signal and quadrature component signal output by the front-end processing unit 1031, one signal or both signals can be selected according to the signal strength to detect the received strength of the sensing signal. Specifically, if one signal (in-phase component signal or quadrature component signal) is selected, then only the selected signal is subjected to smoothing filtering and peak detection; if both signals (in-phase component signal or quadrature component signal) are selected, then smoothing filtering and peak detection can be performed separately. In this case, the change of the peak value of the two signals can be detected. As long as the peak value change of one signal is greater than the preset threshold, it can be determined that a tag or card has been detected. Alternatively, the two selected signals (in-phase component signal or quadrature component signal) can be combined by maximum ratio first, and then smoothing filtering and peak detection can be performed.
[0028] Smoothing filters can be implemented in various ways, such as infinite impulse response low-pass filters (IIR), moving average filters, and Gaussian smoothing filters.
[0029] The communication control module controls the overall communication process and wakes up the RF reader to enter the polling state when the difference between the received strength (i.e., peak value) of the sensed signal and the predefined reference value exceeds a predefined threshold.
[0030] Specifically, such as Figure 3The illustrated radio frequency (RF) communication system includes an RF reader that may further include a storage unit, an MCU, and a matching network. The RF reader and the card device (i.e., card, tag, or card) communicate via proximity. The RF reader detects the card using an LPCD (LPD sensing pulse), and upon detection, wakes up and polls, initiating communication. At great distances, the LPCD sensing pulse remains unchanged, preventing the reader from detecting the card. As the distance increases, the LPCD sensing pulse changes; if a wake-up threshold is reached, it wakes up and polls, enabling communication. The RF reader can be a traditional card reader, an NFC smart device (such as a mobile phone, walkie-talkie, or wearable device like a smartwatch or wristband), or an NFC-enabled device that functions as a card reader. The RF reader communicates via an antenna coupled to the card device (i.e., card, tag, or card). The card device can be a passive or active tag, or an NFC-enabled device that functions as a card device, such as a mobile phone, smartwatch, or wristband.
[0031] like Figure 3 and Figure 4 As shown, the RF card reader uses a communication control module to control the transmission of LPCD sensing signals for card detection. The sensing signal can be an RF carrier with a frequency of fc (fc ranges from 10-18MHz, typically 12-16MHz, specifically 13.56MHz). The RF carrier carries a modulated signal with a short, configurable duration, such as 30-50µs. The time interval between each sensing signal is also configurable, and the transmission frequency is typically a few Hz. The transmitting module generates the sensing signal, which passes through a matching network to the receiving module. The receiving module can detect changes in the sensing signal through a series of processing steps. If a card device approaches, the sensing signal will show amplitude or phase changes, which can be detected by the receiving module. For example, if a change in the sensing signal is detected and the change exceeds a detection threshold, the module will wake up and poll. Accurately detecting such weak changes in the sensing signal requires high detection sensitivity and anti-interference performance. Therefore, in the LPCD card detection stage, the type of sensing signal transmitted and the method of measuring the sensing signal become key limiting factors.
[0032] The RFID reader provided in this invention adds a modulation signal to the sensing signal used for card detection and includes a baseband processing unit to perform a series of processes such as matched filtering and smoothing filtering on the in-phase component signal and / or the quadrature component signal, or the combined signal of both, of the received sensing signal. This avoids the influence of noise and interference, improves the accuracy of peak measurement values, and makes the RFID reader suitable for scenarios requiring the detection of small tags or weakly coupled tags. Specifically, a lower threshold can be set to improve the sensitivity of card detection and avoid missed detections. Since the influence of noise and interference is avoided, false detections will not occur, ensuring the accuracy of card detection. This not only ensures timely RFID communication response but also minimizes power consumption (false detections can lead to false wake-ups of the RFID reader's polling, which increases power consumption).
[0033] Low-power card detection schemes in related technologies include those based on impedance change detection and those based on changes in transmitted sensing pulses or sensing signals. Detection of changes in sensing signals generally includes the following methods: 1. Transmit a sensing RF carrier and detect the envelope analog quantity; 2. Transmit a sensing RF carrier and detect the digital envelope value, i.e., the envelope value after analog-to-digital conversion (ADC); 3. The sensing RF carrier is sent and processed through mixing, filtering, amplification, etc., to obtain the in-phase (I) and quadrature (Q) components after ADC, that is, the change of DC of the detection signal.
[0034] However, these three methods have limitations; they are difficult to detect changes in sensing signals in scenarios with small tags and weak coupling.
[0035] Therefore, this embodiment adopts the following low-power card detection scheme: The system transmits a designed sensing signal, which can be a modulated signal. After transmission, the signal undergoes analog and baseband processing in the receiving link, including mixing, filtering, and amplification, to obtain the in-phase (I) and quadrature (Q) components after ADC processing. These components are then processed by digital baseband to detect changes in the intensity of the corresponding sensing signal. This low-power card detection scheme ensures that the LPCD detection card and the reader maintain consistent receiving sensitivity, thus solving the sensitivity and stability issues of LPCD card detection in weakly coupled scenarios.
[0036] For example, such as Figure 5As shown, after the sensing signal passes through the transmitting module, due to the influence of channel noise and interference, the signal sensed by the receiving module becomes unrecognizable. If the method of detecting the envelope of the sensing signal or the average value of the I / Q signal is used, it is difficult to identify the modulated part. However, after a series of processing by the receiving module, such as... Figure 6 and Figure 7 As shown, even with noise and interference signals, the peak value of the modulation part in the sensing signal can still be obtained accurately and clearly.
[0037] Furthermore, in the RF card reader provided in this embodiment, matched filtering occurs before channel combining in the receiving link, and smoothing filtering follows matched filtering, improving the accuracy of peak detection and thus increasing the card detection accuracy. The sensing signal in this embodiment can be directly transmitted through the card reader's transmitting link; therefore, the card reader provided in this embodiment can be a single card reader device, not necessarily an NFC device, and does not require activating internal tag load modulation to transmit signals. That is, the RF card reader provided in this embodiment can be used not only in NFC systems applied to mobile phones and some wearable smart devices, but also in traditional card reader devices.
[0038] The radio frequency card reader with low-power card detection function provided in this embodiment of the invention can be applied not only to radio frequency communication systems that need to detect physical or virtual smart cards, but also to radio frequency communication systems that need to detect, for example, radio frequency identification (RFID) tags or near field communication (NFC) tags.
[0039] Some optional implementations, such as Figure 2 As shown, the front-end processing unit 1031 includes at least a mixing subunit (i.e., a mixer), a filtering subunit (i.e., a filter), and an amplification subunit (i.e., a baseband amplifier) connected in sequence. The front-end processing unit also includes a gain control subunit (i.e., an automatic gain controller), which adjusts the gain of the amplification subunit based on the signal output by the amplification subunit.
[0040] Specifically, such as Figure 2 As shown, the front-end processing unit 1031 includes two processing circuits. Each circuit includes a mixing sub-unit (i.e., mixer), a filtering sub-unit (i.e., filter), and an amplification sub-unit (i.e., baseband amplifier) connected in sequence. The different processing circuits are used to process the received sensing signals to obtain in-phase component signals and quadrature component signals, respectively.
[0041] The RF card reader provided in this embodiment has a gain control subunit in the receiving link, which can improve the accuracy of subsequent peak detection, thereby improving the card detection accuracy.
[0042] In some optional embodiments, the gain control subunit adjusts the gain of the amplification subunit based on the signal output by the amplification subunit and the radio frequency field strength of the sensing signal received by the front-end processing unit.
[0043] Specifically, such as Figure 2 As shown, the front-end processing unit 1031 includes two processing circuits. Each circuit includes a mixing subunit (i.e., a mixer), a filtering subunit (i.e., a filter), and an amplification subunit (i.e., a baseband amplifier) connected in sequence. The different processing circuits are used to process the received sensing signals to obtain in-phase and quadrature component signals, respectively. The gain control subunit (i.e., automatic gain controller) adjusts the gain of the amplification subunit in the processing circuit that obtains the in-phase component signal based on the in-phase component signal; the gain control subunit (i.e., automatic gain controller) adjusts the gain of the amplification subunit in the processing circuit that obtains the quadrature component signal based on the quadrature component signal.
[0044] Some optional implementations, such as Figure 2 As shown, the front-end processing unit further includes an RF attenuator, which is used to adjust the RF field strength of the sensing signal received by the front-end processing unit. The gain control subunit adjusts the gain of the amplification subunit based on the signal output by the amplification subunit and the RF field strength adjusted by the RF attenuator.
[0045] In some optional embodiments, the sensing signal includes a modulation signal and a carrier signal; the sensing signal satisfies at least one of the following conditions: The modulation signal is located in the middle of the carrier signal; The duty cycle of the modulation signal is between 20% and 80%. The frequency of the carrier signal is fc, and the value of fc ranges from 10 to 18 MHz, generally from 12 to 16 MHz, and specifically it can be 13.56 MHz; The baseband frequency of the modulation signal is fc / 8 or fc / 16, for example, it can be 847.5KHz; The modulation depth of the modulated signal is between 1% and 95%. The total duration of the sensed signal is less than 40 microseconds; The duration of the modulated signal is between a few microseconds and tens of microseconds, for example, between 5 microseconds and 30 microseconds.
[0046] Of course, the total duration of the sensing signal is not limited to less than 40 microseconds; in some other implementations, it can exceed 40 microseconds, such as 100 microseconds. Similarly, the duration of the modulation signal is not limited to between 5 and 30 microseconds.
[0047] like Figure 8 and Figure 9 As shown, the design of the sensing signal can consist of a 13.56MHz RF carrier with duration T1, a signal with modulation portion T2, and a 13.56MHz RF carrier with duration T3. The durations T1, T2, and T3 are configurable and are generally integer multiples of the 13.56MHz RF carrier period. For example, a typical value for T1 is configurable as 128 13.56MHz RF carrier periods, approximately 9.44µs. The duration T2 is configured based on the modulation signal, and its duty cycle can be arbitrarily designed, typically set to 20%-80%. The modulation depth is configurable, for example, between 5%-95%, with a typical value of 30%. A typical value for T3 is configurable as 128 13.56MHz RF carrier periods, approximately 9.44µs.
[0048] For example, such as Figure 10 and Figure 11 As shown, the duty cycle of the modulated signal with duration T2 can be 50%. In this case, the baseband frequency is, for example, 847.5 kHz. After modulation by a 13.56 MHz carrier, its duration is at least two 847.5 kHz cycles, approximately 4.72 μs, or four 847.5 kHz cycles, approximately 9.44 μs, or eight 847.5 kHz cycles, approximately 18.88 μs. A typical value is configured as four 847.5 kHz cycles, approximately 9.44 μs.
[0049] like Figure 12 As shown, the designed sensing signal consists of two 13.56MHz RF carriers and an 847.5KHz modulation signal in the middle. Its total duration T = T1 + T2 + T3 is configurable, and its typical value is 9.44 + 9.44 + 9.44 = 28.32us, which is lower than the 40-50us design of low-power card detection schemes in related technologies, further saving LPCD card detection power consumption.
[0050] In this embodiment, the sensing signal can take various forms; the duty cycle, modulation depth, and duration can be designed according to actual needs. Furthermore, the baseband signal can have a phase transition or not.
[0051] This embodiment provides a state switching method for an RFID card reader, which can be used for any of the RFID card readers described above. Figure 13 This is a flowchart of a state switching method for an RFID card reader according to an embodiment of the present invention, such as... Figure 13 As shown, the process includes the following steps: Step S1301: The transmitting module transmits a sensing signal with a modulated signal; In step S1302, the front-end processing unit in the receiving module processes the received sensing signal to obtain the corresponding in-phase component signal and quadrature component signal. In step S1303, the baseband processing unit in the receiving module performs matched filtering on the in-phase component signal and the quadrature component signal respectively to obtain a first signal and a second signal. It selects at least one of the first signal and the second signal for smoothing filtering and peak detection to obtain the target peak measurement value, or it performs combined processing on the first signal and the second signal and then performs smoothing filtering and peak detection to obtain the target peak measurement value. Step S1304: The communication control module controls the entry into the polling state based on the target peak measurement value.
[0052] The state switching method for an RFID reader provided in this embodiment adds a modulation signal to the sensing signal used for card detection and sets up a baseband processing unit to perform a series of processes such as matched filtering and smoothing filtering on the in-phase component signal and / or the quadrature component signal, or the combined signal of the two, of the received sensing signal. This avoids the influence of noise and interference, improves the accuracy of peak measurement values, and makes the RFID reader suitable for scenarios that require detection of small tags or weakly coupled tags. Specifically, a lower threshold can be set to improve the sensitivity of card detection and avoid missed detections. Since the influence of noise and interference is avoided, false detections will not occur, ensuring the accuracy of card detection. This not only ensures timely RFID communication response but also minimizes power consumption (false detections will cause false wake-ups of the RFID reader's polling, which will increase power consumption).
[0053] In some optional embodiments, step S1302, i.e., the front-end processing unit in the receiving module, processes the received sensing signal to obtain the corresponding in-phase component signal and quadrature component signal, including: In step S13021, the front-end processing unit performs mixing, filtering and amplification processing on the sensing signal in two separate paths to obtain the in-phase component signal and the quadrature component signal.
[0054] like Figure 2 The transmitting module sends a sensing signal, which is then sent to the receiving module for measurement, specifically its changes. In the receiving module, the sensing signal undergoes attenuation, IQ mixing, filtering, amplification, ADC quantization, and then baseband processing to obtain the measured value of the sensing signal. This measured value is the peak value of the signal with the modulation portion. Baseband processing mainly includes matched filtering, channel combining (or channel selection), smoothing filtering, and peak search.
[0055] For the technical details in this embodiment, please refer to the above embodiment of the RFID card reader. Repeated content will not be repeated here.
[0056] In some optional embodiments, the sensing signal includes a modulation signal and a carrier signal; the sensing signal satisfies at least one of the following conditions: The modulation signal is located in the middle of the carrier signal; The duty cycle of the modulation signal is between 20% and 80%. The frequency of the carrier signal is fc, and the value of fc ranges from 10 to 18 MHz; The baseband frequency of the modulation signal is fc / 8 or fc / 16; The modulation depth of the modulated signal is between 1% and 95%. The total duration of the sensed signal is less than 40 microseconds; The duration of the modulation signal is between 5 microseconds and 30 microseconds.
[0057] For a description of the sensing signals in this embodiment, please refer to the above embodiment of the RFID card reader. Repeated content will not be repeated here.
[0058] In some optional embodiments, the baseband processing unit selects the first signal and the second signal, and performs smoothing filtering and peak detection on the first signal and the second signal respectively to obtain two target peak measurement values. When one of the target peak measurement values is greater than a first preset threshold, the communication control module controls the system to enter a polling state. or, The baseband processing unit selects the first signal and the second signal, and performs maximum ratio merging on the first signal and the second signal respectively. The merged signal is then smoothed, filtered, and peak detected to obtain the target peak measurement value. When the target peak measurement value is greater than a second preset threshold, the communication control module controls the system to enter a polling state.
[0059] In this embodiment, the processing flow of the receiving link for the sensing signal is as follows: after passing through the RF front end, the digital domain I / Q channels are respectively matched and filtered, and then channel selection is performed. Channel selection can choose to output both channels, then smooth and filter them separately, and then perform peak detection separately, or only one channel can be selected for output, or the two channels can be combined by maximum ratio. The output signal is then smoothed and filtered, and the detected peak value is used as the measurement value. When both channels output peak values, the change in the peak values of the two channels can be detected. As long as the peak value change value of one channel is greater than the preset threshold, it can be determined that a tag or card has been detected.
[0060] In this embodiment, if the detected change in the peak value is greater than a preset threshold, that is, if the wake-up condition for polling is met, the RFID reader is woken up for polling. After waking up, the RFID reader polls for card types such as Type A, Type B, Type F, and Type V. If a card responds and the reader can demodulate it correctly, the normal communication process begins (the reader and the card establish normal communication); otherwise, polling continues.
[0061] The state switching method for RFID card readers provided in this embodiment can be used not only in the NFC systems of mobile phones and some wearable smart devices, but also in traditional card reader devices.
[0062] In summary, this invention provides a low-power card detection method. This LPCD technology solution, through the design of a suitable sensing signal and the processing of matched filtering and smoothing filtering in the receiving demodulation link, has strong anti-noise and interference capabilities. The measurement value obtained by peak search is more accurate and reliable, enabling high-sensitivity detection in small tag weak coupling scenarios and reducing the probability of false detection.
[0063] In addition, the total pulse duration of the sensing signal can be shortened to the order of 15-40us. The pulse duration is about 30-50us when the I / Q signal value is calculated by averaging, and the pulse duration is about 50-200us when the field envelope is detected. Furthermore, the detection sensitivity of the latter two is not as good as that of the former, which further reduces the overall power consumption of LPCD.
[0064] This invention provides an electronic device having any of the aforementioned radio frequency card readers. This electronic device can be a smartphone or a wearable device such as a smartwatch.
[0065] In addition, such as Figure 14 As shown, the electronic device may further include a processor (e.g., a central processing unit, a graphics processor, etc.) 1401, which can perform various appropriate actions and processes according to a program stored in read-only memory (ROM) 1402 or a program loaded from memory 1408 into random access memory (RAM) 1403. The RAM 1403 also stores various programs and data required for the operation of the electronic device. The processor 1401, ROM 1402, and RAM 1403 are interconnected via bus 1404. An input / output (I / O) interface 1405 is also connected to bus 1404.
[0066] Typically, the following devices can be connected to I / O interface 1405: input devices 1406 including, for example, touchscreens, touchpads, keyboards, mice, cameras, microphones, accelerometers, gyroscopes, etc.; output devices 1407 including, for example, liquid crystal displays (LCDs), speakers, vibrators, etc.; memory devices 1408 including, for example, magnetic tapes, hard disks, etc.; and communication devices 1409 (including RFID card readers). Communication device 1409 allows electronic devices to communicate wirelessly or wiredly with other devices to exchange data. Although Figure 14 Electronic devices with various devices are shown, but it should be understood that it is not required to implement or have all of the devices shown, and more or fewer devices may be implemented or have instead.
[0067] Figure 14 The electronic device shown is merely an example and should not be construed as limiting the functionality and scope of use of the embodiments of the present invention.
[0068] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and all such modifications and variations fall within the scope defined by the appended claims.
Claims
1. An RFID card reader, characterized in that, At least including: Communication control module, transmitting module, and receiving module; The transmitting module is used to transmit a sensing signal with a modulated signal; The receiving module includes a front-end processing unit and a baseband processing unit; The front-end processing unit is used to process the received sensing signal to obtain the corresponding in-phase component signal and quadrature component signal; The baseband processing unit includes a matched filtering subunit, a channel selection subunit or a channel combining subunit, a smoothing filtering subunit, and a peak search subunit connected in sequence. The baseband processing unit is used to process the in-phase component signal and / or the quadrature component signal output by the front-end processing unit to obtain a target peak measurement value. The target peak measurement value includes the peak measurement value of the modulation signal. The communication control module is used to control the entry into a polling state based on the target peak measurement value.
2. The radio frequency card reader according to claim 1, characterized in that, The front-end processing unit includes at least a mixing subunit, a filtering subunit, and an amplification subunit connected in sequence. The front-end processing unit further includes a gain control subunit, which adjusts the gain of the amplification subunit based on the signal output by the amplification subunit.
3. The radio frequency card reader according to claim 2, characterized in that, The gain control subunit adjusts the gain of the amplification subunit based on the signal output by the amplification subunit and the radio frequency field strength of the sensing signal received by the front-end processing unit.
4. The radio frequency card reader according to claim 3, characterized in that, The front-end processing unit further includes an RF attenuator, which is used to adjust the RF field strength of the sensing signal received by the front-end processing unit. The gain control subunit adjusts the gain of the amplification subunit based on the signal output by the amplification subunit and the RF field strength adjusted by the RF attenuator.
5. The radio frequency card reader according to claim 1, characterized in that, The sensing signal includes a modulation signal and a carrier signal; the sensing signal satisfies at least one of the following conditions: The modulation signal is located in the middle of the carrier signal; The duty cycle of the modulation signal is between 20% and 80%. The frequency of the carrier signal is fc, and the value of fc ranges from 10 to 18 MHz; The baseband frequency of the modulation signal is fc / 8 or fc / 16; The modulation depth of the modulated signal is between 1% and 95%. The total duration of the sensed signal is less than 40 microseconds; The duration of the modulation signal is between 5 microseconds and 30 microseconds.
6. A state switching method for an RFID card reader, characterized in that, The method, applied to the radio frequency card reader according to any one of claims 1-5, comprises: The transmitting module transmits a sensing signal with modulation. The front-end processing unit in the receiving module processes the received sensing signal to obtain the corresponding in-phase component signal and quadrature component signal; The baseband processing unit in the receiving module performs matched filtering on the in-phase component signal and the quadrature component signal respectively to obtain a first signal and a second signal. It selects at least one of the first signal and the second signal for smoothing filtering and peak detection to obtain the target peak measurement value, or it combines the first signal and the second signal and then performs smoothing filtering and peak detection to obtain the target peak measurement value. The communication control module controls the entry into a polling state based on the target peak measurement value.
7. The method according to claim 6, characterized in that, The front-end processing unit in the receiving module processes the received sensing signal to obtain the corresponding in-phase component signal and quadrature component signal, including: The front-end processing unit performs mixing, filtering, and amplification processing on the sensed signal in two separate paths to obtain the in-phase component signal and the quadrature component signal.
8. The method according to claim 6, characterized in that, The sensing signal includes a modulation signal and a carrier signal; the sensing signal satisfies at least one of the following conditions: The modulation signal is located in the middle of the carrier signal; The duty cycle of the modulation signal is between 20% and 80%. The frequency of the carrier signal is fc, and the value of fc ranges from 10 to 18 MHz; The baseband frequency of the modulation signal is fc / 8 or fc / 16; The modulation depth of the modulated signal is between 1% and 95%. The total duration of the sensed signal is less than 40 microseconds; The duration of the modulation signal is between 5 microseconds and 30 microseconds.
9. The method according to claim 6, characterized in that, The baseband processing unit selects the first signal and the second signal, and performs smoothing filtering and peak detection on the first signal and the second signal respectively to obtain two target peak measurement values. When one of the target peak measurement values is greater than a first preset threshold, the communication control module controls the system to enter a polling state. or, The baseband processing unit selects the first signal and the second signal, and performs maximum ratio merging on the first signal and the second signal respectively. The merged signal is then smoothed, filtered, and peak detected to obtain the target peak measurement value. When the target peak measurement value is greater than a second preset threshold, the communication control module controls the system to enter a polling state.
10. An electronic device, characterized in that, include: The radio frequency card reader according to any one of claims 1 to 5.