An acoustic positioning multi-tag identification and wake-up system and method

Abstract

This application relates to the field of acoustic positioning technology, providing an acoustic positioning multi-tag identification and wake-up system and method. The system includes a transmitter and a receiver. The transmitter modulates the unique identification information of the tag onto an acoustic carrier wave according to a preset frame structure through an encoding modulation circuit, forming an encoded acoustic signal containing a preamble, a pattern code, and ID data. Simultaneously, it transmits an RFID signal. The receiver's decoding circuit receives the signal and performs a two-stage wake-up detection using its integrated frequency detection and pattern correlator. An interrupt is generated only when the pattern code matches, waking up the main control unit. The main control unit reads the decoded ID and performs pairing verification with the ID in the RFID signal. For successfully paired tags, the distance is calculated based on the arrival time difference between the two signals. This application effectively solves the signal conflict problem when multiple tags are working concurrently through encoded acoustic waves, dual-wave pairing, and an intelligent wake-up mechanism.

Description

Technical Field

[0001] This application relates to the field of acoustic positioning technology, specifically to an acoustic positioning multi-tag identification and wake-up system and method. Background Technology

[0002] Acoustic positioning technology is widely used in indoor positioning, robot navigation, and other fields due to its advantages such as low cost and ease of implementation. However, the difficulty in carrier modulation of acoustic signals results in acoustic positioning signals having only frequency characteristics, and few coding techniques are available. This means that in the case of multi-tag item positioning, only time-division multiplexing can be used for round-robin operation, which consumes too much time resources and limits the total number of tags, thus affecting the scope of application of the technology.

[0003] In practical applications involving multiple tags and high concurrency, existing acoustic localization technologies suffer from the following problems:

[0004] 1. Traditional acoustic positioning systems typically rely on the frequency characteristics of the signal itself or simple time-division multiplexing (TDM) for tag differentiation. Because acoustic signal carrier modulation is relatively difficult, unlike radio frequency signals which require complex coding and modulation, the number of tags that can be simultaneously identified and differentiated in a single system is extremely limited. Most systems can only query each tag sequentially through time-slice polling, which not only consumes significant time resources, resulting in a low positioning refresh rate, but also severely limits the total number of tags the system can accommodate. This makes it impossible to meet the real-time, concurrent positioning needs of hundreds or even thousands of targets in large-scale warehousing and logistics sorting scenarios.

[0005] 2. The speed of sound propagation in air is easily affected by environmental factors such as temperature, humidity, air pressure, and wind speed, leading to inherent biases in calculation models based on a fixed sound speed. These errors are amplified when coordinates are calculated using positioning algorithms, causing the final positioning results to drift and making it difficult to maintain accuracy at the centimeter level.

[0006] To address environmental interference, existing technologies have proposed several improvement schemes. For example, Chinese patent CN120428169B discloses a method for dynamically correcting errors by introducing a reference tag with a known location. This system calculates a deviation ratio coefficient between the actual coordinates of the reference tag and the coordinates measured by the system, and applies this coefficient to correct the coordinates of the working tag. Simultaneously, it dynamically compensates for the speed of sound by incorporating parameters such as temperature, humidity, and wind speed, thereby improving positioning accuracy in complex environments to a certain extent.

[0007] This technical solution is still based on traditional tag polling or limited concurrent identification. It does not solve the fundamental problem of signal collision and identification when multiple tags are working concurrently. The system still needs to process the signals of each tag one by one. When the number of tags increases dramatically, the reference data acquisition cycle required to calculate the correction coefficient becomes longer, and the overall system response is sluggish, making it impossible to achieve true real-time, high-concurrency, and high-precision positioning. In addition, the continuous operation of tags also leads to higher overall power consumption. Summary of the Invention

[0008] To help solve the above-mentioned technical problems, this application provides a sound wave positioning multi-tag identification and wake-up system and method.

[0009] A multi-tag identification system for acoustic positioning, comprising a base station and at least one tag;

[0010] The tag includes a first main control unit, and a radio frequency transmission module and an acoustic wave transmission module, both connected to the first main control unit. The first main control unit is configured to control the radio frequency transmission module to send a radio frequency signal containing the tag's unique identification code, and to control the acoustic wave transmission module to send an acoustic wave signal modulated by digital encoding. The data frame structure of the acoustic wave signal includes at least a carrier wave, a preamble, a mode code, and data content.

[0011] The base station includes a second main control unit, and a radio frequency receiving module and an acoustic wave receiving module, both of which are connected to the second main control unit.

[0012] The acoustic wave receiving module includes an acoustic wave receiving probe and an acoustic wave decoding circuit; the acoustic wave receiving probe is used to receive acoustic wave signals and convert them into analog electrical signals; the acoustic wave decoding circuit is configured to perform envelope detection and digital slicing processing on the analog electrical signals to extract digital bit streams.

[0013] The acoustic decoding circuit is also configured to activate the second main control unit when a preset matching code is identified from the digital bitstream;

[0014] The second main control unit is configured to read the data content in the acoustic signal and calculate the distance between the tag and the base station based on the time difference of arrival of the radio frequency signal and the acoustic signal.

[0015] The data frame structure of the acoustic signal includes, in sequence, a carrier wave, a preamble, a mode code, and data content. The data content contains the unique identification code of the tag. The acoustic decoding circuit includes a programmable gain amplifier, a bandpass filter, and an envelope detector connected in sequence. The programmable gain amplifier is used to amplify the analog electrical signal, and the center frequency of the bandpass filter is matched with the carrier frequency of the acoustic signal.

[0016] The acoustic wave decoding circuit is a dedicated integrated circuit chip integrating a programmable gain amplifier, an envelope detector, a clock recovery circuit, and a decoder. The acoustic wave decoding circuit is equipped with a register for storing preset wake-up modes. The acoustic wave decoding circuit is configured to compare the extracted mode code with the preset wake-up mode in the register, and output a wake-up signal when they match. The second main control unit is configured as follows:

[0017] Extract the unique identification code of the tag from the data content of the sound wave signal;

[0018] The identification code obtained from the radio frequency signal is paired and verified with the identification code extracted from the sound wave signal;

[0019] Distance calculation based on the time difference of arrival is performed only when a pairing is successful.

[0020] A method for acoustic localization multi-label recognition, wherein, based on the aforementioned acoustic localization multi-label recognition system, the method includes:

[0021] A1: The tag synchronously transmits a radio frequency signal containing its unique identification code and a digitally encoded and modulated acoustic signal. The data frame structure of the acoustic signal includes at least a carrier wave, a preamble, a mode code, and data content.

[0022] A2: The acoustic wave signal is received by the acoustic wave receiving probe of the base station and converted into an analog electrical signal;

[0023] A3: The base station's acoustic decoding circuit performs envelope detection and digital slicing processing on the analog electrical signal to extract the digital bit stream, and activates the base station's main control unit when a preset matching code is identified from the digital bit stream.

[0024] A4: The main control unit of the activated base station reads the identification code from the acoustic signal data content and calculates the distance between the tag and the base station based on the arrival time difference between the radio frequency signal and the acoustic signal.

[0025] A multi-tag identification system for acoustic positioning, comprising a base station and at least one tag:

[0026] Base stations include:

[0027] A first acoustic transmitter is used to transmit a first coded acoustic signal to the tag;

[0028] A first radio frequency transmitter is used to send a first radio frequency signal containing the unique identification information of the base station to the tag;

[0029] The first encoding modulation circuit has an input terminal connected to a basic carrier signal and an encoding control signal, and an output terminal connected to a second acoustic wave transmitter. It is used to modulate the unique identification information of the base station onto the basic carrier signal according to a preset frame structure. The frame structure of the first encoded acoustic wave signal includes a preamble for signal synchronization, a mode code for triggering wake-up, and data content containing the unique identification information of the base station.

[0030] A first acoustic receiver is used to receive a second coded acoustic signal from the tag;

[0031] The first decoding circuit is used to decode the received second coded acoustic signal and extract the unique identification information of the tag;

[0032] The first main control unit is used to read the unique identification information of the tag extracted by the first decoding circuit and to pair and verify it with the unique identification information in the received second radio frequency signal. For tags that are successfully paired, the distance between the tag and the base station is calculated based on the time difference between the arrival of the second coded acoustic wave signal and the second radio frequency signal at the base station.

[0033] Tags include:

[0034] The second acoustic receiver is used to receive the first coded acoustic signal sent by the base station;

[0035] The second decoding circuit is used to decode the first coded acoustic signal and generate a wake-up interrupt when the decoded pattern code matches the preset wake-up code in the tag through a wake-up detection mechanism.

[0036] The second acoustic transmitter is used to send a second coded acoustic signal to the base station after the tag is woken up;

[0037] The second radio frequency transmitter is used to synchronously transmit a second radio frequency signal containing the tag's unique identification information;

[0038] The second encoding modulation circuit has an input terminal connected to the basic carrier signal and the encoding control signal, and an output terminal connected to the first acoustic wave transmitter. It is used to modulate the unique identification information of the tag onto the basic carrier signal according to a preset frame structure. The frame structure of the second encoded acoustic wave signal includes at least a preamble for signal synchronization and data content containing the unique identification information of the tag.

[0039] The second main control unit, in response to a wake-up interrupt, controls the tag to wake up from its sleep state and controls the second acoustic transmitter and the second radio frequency transmitter to send the second coded acoustic signal and the second radio frequency signal.

[0040] The encoding and modulation circuit includes:

[0041] The signal shaping link consists of multiple inverters connected in series. The input terminal receives the encoding control signal, which is used to invert and delay the signal.

[0042] The modulation core circuit includes a differential pair module and a current mirror module;

[0043] The differential pair module is composed of an NPN transistor and a PNP transistor connected in a complementary manner. Its first input terminal is connected to the output signal of the signal shaping link, and its second input terminal is connected to the fundamental carrier signal.

[0044] The current mirror module is connected to the power supply path of the differential pair module to provide operating current to the differential pair module;

[0045] The processed encoding control signal output from the signal shaping link is used to control the conduction state of the complementary transistors in the differential pair module, so that the basic carrier signal is selected or its amplitude is changed according to the logic level of the encoding control signal.

[0046] The output of the modulation core circuit outputs the carrier signal processed by the differential pair module, which serves as the encoded acoustic signal.

[0047] The acoustic decoding circuit includes:

[0048] The acoustic wave sensing module uses a piezoelectric ultrasonic receiver to convert the received coded acoustic wave signal into an analog electrical signal.

[0049] The signal conditioning module, electrically connected to the output of the acoustic wave sensing module, is used to amplify, filter, and transform the analog electrical signal. The signal conditioning module includes:

[0050] The preamplifier uses an operational amplifier to form a non-inverting amplifier circuit. Its non-inverting input is connected to the output of the acoustic wave sensing module to perform primary amplification of the analog electrical signal.

[0051] A bandpass filter, whose input is connected to the output of a preamplifier, has a center frequency that matches the carrier frequency of the encoded acoustic signal and is used to filter out out-of-band noise.

[0052] The impedance transformation circuit uses a voltage follower. The non-inverting input is connected to the output of the bandpass filter, and the output is used as the output of the signal conditioning module to convert high output impedance to low output impedance.

[0053] The decoding chip has its signal input pin connected to the output of the impedance transformation circuit. It is used to decode the conditioned analog electrical signal. The decoding chip integrates a programmable gain amplifier, envelope detector, data slicer, clock recovery circuit and decoder. It is used to perform signal amplification, filtering, digitization, synchronization and decoding operations. After the decoding verification is successful, it outputs a wake-up interrupt to the main control unit through the interrupt output pin.

[0054] The decoding circuit processes the encoded acoustic signal as follows:

[0055] The received analog acoustic signal is sequentially amplified by programmable gain and then bandpass filtered.

[0056] Envelope detection is performed on the filtered signal to extract the baseband envelope signal;

[0057] The baseband envelope signal is compared with a threshold and converted into a digital bit stream.

[0058] The preamble is detected from the digital bit stream, and the clock signal synchronized with the transmitter is reconstructed from it.

[0059] The reconstructed clock signal is used to decode the digital bit stream following the preamble to obtain the decoded data.

[0060] A method for acoustic localization multi-tag recognition, wherein the method based on the above-mentioned acoustic localization multi-tag recognition system includes the following steps:

[0061] B1: The base station sends an acoustic wake-up signal containing a specific wake-up mode code to the target tag;

[0062] B2: The tag receives the acoustic wake-up signal, decodes the acoustic wake-up signal, and generates a wake-up interrupt to activate from the sleep state when the identified pattern code matches a preset value;

[0063] B3: The activated tag sends a first radio frequency signal and an acoustic positioning signal containing its own unique identification information;

[0064] B4: The base station receives the first radio frequency signal and the acoustic positioning signal, and calculates the distance between the tag and the base station based on the time difference between their arrival.

[0065] In summary, the system of this application has the following advantages:

[0066] 1. By designing a specific frame structure containing preamble, pattern code, and unique identification information, and reliably modulating it onto an acoustic carrier wave using an encoding modulation circuit, each tag's emitted acoustic signal possesses a globally unique identification code at the physical layer. This enables the system to analyze and distinguish different tags from mixed and superimposed acoustic signals, overcoming the capacity limitations of traditional acoustic positioning that relies on time-division polling. At the transmitting end, the precise modulation capabilities of differential pairs and current mirrors in the encoding modulation circuit ensure the quality and anti-interference performance of the encoded signal.

[0067] 2. The core decoding chip in the decoding circuit integrates programmable gain, filtering, clock recovery, and decoding functions. Together with a preset wake-up code, they form a two-stage low-power wake-up mechanism. This mechanism ensures that the decoding circuit only triggers an interrupt to wake up the main control unit when it receives a valid signal that perfectly matches the preset mode code, strictly filtering out environmental noise and invalid signals. This allows the tag and base station to remain in a microampere-level sleep state most of the time, only being quickly and accurately woken up when communication is required. Attached Figure Description

[0068] Figure 1 This is a schematic diagram of the frame structure of the encoded acoustic signal in this application;

[0069] Figure 2 A schematic diagram of the code for the information content portion that needs to be sent to define the encoding process of this application;

[0070] Figure 3 This is a code diagram illustrating the encoding operation part of the encoding process in this application;

[0071] Figure 4 This is a schematic diagram of the code for the part of the encoding process of this application that transmits sound wave signals through a power amplifier;

[0072] Figure 5 This is a schematic diagram of the encoding and modulation circuit of this application;

[0073] Figure 6 This is a flowchart illustrating the decoding process of this application;

[0074] Figure 7 This is a flowchart illustrating the decoding process of the received acoustic signal in this application.

[0075] Figure 8 This is a flowchart illustrating the wake-up triggering of the information portion of the decoding process in this application, which receives the signal.

[0076] Figure 9 This is a schematic diagram of the decoding chip portion of the decoding circuit in this application;

[0077] Figure 10This is a schematic diagram of the main control chip portion of the decoding circuit in this application;

[0078] Figure 11 This is a flowchart illustrating the wake-up mechanism of this application;

[0079] Figure 12 This is a schematic diagram of the positioning results of this application. Detailed Implementation

[0080] The present application will be further described below with reference to the accompanying drawings. The structure and principle of the present application are very clear to those skilled in the art. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.

[0081] In one embodiment, this application provides an acoustic positioning multi-tag identification system, including a base station and at least one tag:

[0082] Base stations include:

[0083] A first acoustic transmitter is used to transmit a first coded acoustic signal to the tag;

[0084] A first radio frequency transmitter is used to send a first radio frequency signal containing the unique identification information of the base station to the tag;

[0085] The first encoding modulation circuit has an input terminal connected to a basic carrier signal and an encoding control signal, and an output terminal connected to a second acoustic wave transmitter. It is used to modulate the unique identification information of the base station onto the basic carrier signal according to a preset frame structure. The frame structure of the first encoded acoustic wave signal includes a preamble for signal synchronization, a mode code for triggering wake-up, and data content containing the unique identification information of the base station.

[0086] A first acoustic receiver is used to receive a second coded acoustic signal from the tag;

[0087] The first decoding circuit is used to decode the received second coded acoustic signal and extract the unique identification information of the tag;

[0088] The first main control unit is used to read the unique identification information of the tag extracted by the first decoding circuit and to pair and verify it with the unique identification information in the received second radio frequency signal. For tags that are successfully paired, the distance between the tag and the base station is calculated based on the time difference between the arrival of the second coded acoustic wave signal and the second radio frequency signal at the base station.

[0089] Tags include:

[0090] The second acoustic receiver is used to receive the first coded acoustic signal sent by the base station;

[0091] The second decoding circuit is used to decode the first coded acoustic signal and generate a wake-up interrupt when the decoded pattern code matches the preset wake-up code in the tag through a wake-up detection mechanism.

[0092] The second acoustic transmitter is used to send a second coded acoustic signal to the base station after the tag is woken up;

[0093] The second radio frequency transmitter is used to synchronously transmit a second radio frequency signal containing the tag's unique identification information;

[0094] The second encoding modulation circuit has an input terminal connected to the basic carrier signal and the encoding control signal, and an output terminal connected to the first acoustic wave transmitter. It is used to modulate the unique identification information of the tag onto the basic carrier signal according to a preset frame structure. The frame structure of the second encoded acoustic wave signal includes at least a preamble for signal synchronization and data content containing the unique identification information of the tag.

[0095] The second main control unit, in response to a wake-up interrupt, controls the tag to wake up from its sleep state and controls the second acoustic transmitter and the second radio frequency transmitter to send the second coded acoustic signal and the second radio frequency signal.

[0096] 1. The active wake-up process of the base station

[0097] The base station has complete acoustic / RF transceiver capabilities. When it is necessary to locate a tag, the base station's first main control unit controls the first acoustic transmitter to transmit a first coded acoustic signal (i.e., a wake-up signal), and simultaneously transmits a first RF signal. The frame structure of this wake-up acoustic signal contains a mode code and data content for the base station's own identification.

[0098] The encoding and modulation circuitry is crucial for generating this signal. Specifically, it includes:

[0099] Signal shaping link: It consists of multiple CMOS inverters connected in series, which invert and delay the input encoded control signal (from the main control unit) to shape it.

[0100] The modulation core circuit consists of a differential pair module composed of an NPN transistor Q1 and a PNP transistor Q2, and a current mirror module. The shaped coded signal controls the conduction state of this pair of complementary transistors, thereby modulating or gating the input fundamental carrier signal. The current mirror provides a stable and controllable operating current to the differential pair, ensuring modulation accuracy. The final output is the modulated carrier signal.

[0101] It should be noted that the difference in frame structure between the first and second coded acoustic signals is not determined by the structure of the coding modulation circuit, but by the program logic of the first and second main control units. Specifically, it is determined by the functional type and data content carried by the coding modulation circuit. The first and second coding modulation circuits in this application are identical in circuit structure.

[0102] The encoding modulation circuit is a general-purpose signal modulation hardware channel. Its function is to modulate the encoded control signals (i.e., baseband digital signals) representing logic "0" and "1" onto a fundamental carrier at a specific frequency, generating a modulated acoustic signal that can be transmitted in the channel. This circuit itself does not define or distinguish frame structures; it only performs the physical conversion function of outputting the corresponding modulated waveform based on the input digital sequence. The specific definition and differences in frame structures depend entirely on the generation rules of the encoded control signals input to the encoding modulation circuit, which are implemented by the main control unit.

[0103] 2. Tag Response and Location Process

[0104] When the tag is not invoked, its second main control unit and most of the circuitry are in deep sleep mode, with only the second acoustic receiver and the second decoding circuit in a monitoring state with extremely low power consumption.

[0105] When the tag's second decoding circuit receives the wake-up acoustic signal from the base station, and after decoding and pattern matching, compares it with its own preset wake-up code, a wake-up interrupt is generated. This interrupt wakes the tag's second main control unit from sleep mode. The activated main control unit then controls the tag's second acoustic transmitter and second radio frequency transmitter to synchronously transmit a second coded acoustic signal and a second radio frequency signal (i.e., a response signal) containing the tag's unique ID.

[0106] The base station's first acoustic receiver and first radio frequency receiver receive the tag's response signal, respectively. The acoustic signal is decoded to obtain the tag ID, which is then paired and verified against the ID in the radio frequency signal. The time difference of arrival is calculated for successfully verified signals to determine the tag's distance.

[0107] Specifically, the encoding and modulation circuit includes:

[0108] The signal shaping link consists of multiple inverters connected in series. The input terminal receives the encoding control signal, which is used to invert and delay the signal.

[0109] The modulation core circuit includes a differential pair module and a current mirror module;

[0110] The differential pair module is composed of an NPN transistor and a PNP transistor connected in a complementary manner. Its first input terminal is connected to the output signal of the signal shaping link, and its second input terminal is connected to the fundamental carrier signal.

[0111] The current mirror module is connected to the power supply path of the differential pair module to provide operating current to the differential pair module;

[0112] The processed encoding control signal output from the signal shaping link is used to control the conduction state of the complementary transistors in the differential pair module, so that the basic carrier signal is selected or its amplitude is changed according to the logic level of the encoding control signal.

[0113] The output of the modulation core circuit outputs the carrier signal processed by the differential pair module, which serves as the encoded acoustic signal.

[0114] Specifically, this circuit is an encoded carrier modulation circuit. Its core function is to modulate the input fundamental carrier through an encoded control signal to generate an output modulated carrier.

[0115] I. Signal Processing Logic

[0116] 1. Encoding control signal processing:

[0117] The encoded control signal is processed by a multi-stage inverter (the inverter connected in series after the "C" input in the figure) to realize the inversion, delay or logic transformation of the signal (the inverter can realize the phase flip of the signal, the multi-stage series can introduce delay, or cooperate with the subsequent circuit to realize specific logic functions).

[0118] 2. Carrier modulation implementation:

[0119] The processed coded control signal interacts with the "input fundamental carrier" ("A" input in the diagram) in a differential amplifier structure (complementary transistor pairs in the circuit, such as an NPN and PNP combination). The differential amplifier replicates and controls the current through a current mirror, and modulates the amplitude, phase, or frequency of the input carrier by combining the switching characteristics of the transistors, ultimately outputting a "modulated carrier" ("B" output in the diagram).

[0120] II. Circuit Structure and Component Functions

[0121] Inverter Link: Multi-stage inverters are used for signal preprocessing to ensure that the phase and timing of the encoded control signals match those of subsequent circuits.

[0122] Differential Amplification and Current Mirror: Differential amplifiers achieve differential amplification and modulation of signals through transistor topologies such as common emitter / common base; current mirrors precisely control the current flow direction to ensure modulation accuracy.

[0123] Power supply and ground: VCC provides the operating voltage for the circuit, and ground (GND) serves as the reference potential, together supporting the circuit's level conversion and signal processing.

[0124] The purpose of this application is to provide a sound wave triggering, encoding / decoding technology and system that assigns a unique ID number to each tag's transmitted sound wave. By pairing the RFID and USID transmitted by each tag, the base station can achieve high-precision, high-concurrency identification and positioning of a large number of tags, effectively solving the problem of multi-tag signal conflict. Simultaneously, it can independently wake up smart tags within the sound wave coverage area, ensuring that during non-working hours, the tags can enter sleep mode with microamplitude power consumption, significantly saving unnecessary power consumption.

[0125] The tag and base station employ a dual-probe scheme, with one probe transmitting acoustic signals and the other receiving them. The receiving probe is connected to a decoding chip for acoustic signal decoding.

[0126] I. Sound Wave Emission Process

[0127] 1. The MCU controls the generation of a 19kHz signal in the form of carrier wave + preamble + mode code + data content.

[0128] 2. Acoustic communication operates at a rate of 1ms / bit, and every 200ms cycle, it sequentially sends 1 byte of 0xFF, 1 byte of 0x55, and then appends 2 bytes of custom data, while referring to the limit transmission distance requirement of 60m.

[0129] 3. Simultaneously transmit its own RFID tag while sending sound waves.

[0130] II. Sound Wave Reception Process

[0131] 1. Sound wave recognition: The carrier signal arrives first, the decoding chip is activated, and it begins to prepare to receive data.

[0132] 2. Synchronization: The preamble follows immediately, helping the chip to stably lock the clock rhythm.

[0133] 3. Verification: Finally, the chip compares the mode code bit by bit. Only when all parts are correct will the decoding chip finally generate a wake-up signal (IRQ) to wake up the subsequent microcontroller (MCU). The base station collects the acoustic signal emitted by the tag, reverse-decodes it into binary, and compares it with the mode code of the transmitting end. The comparison result triggers a wake interrupt.

[0134] The second decoding circuit includes:

[0135] The acoustic wave sensing module (not shown in the figure) uses a piezoelectric ultrasonic receiver to convert the received coded acoustic wave signal into an analog electrical signal.

[0136] The signal conditioning module (not shown in the figure) is electrically connected to the output of the acoustic wave sensing module and is used to amplify, filter, and transform the analog electrical signal. The signal conditioning module includes:

[0137] The preamplifier (not shown in the figure) uses an operational amplifier to form a non-inverting amplifier circuit. Its non-inverting input is connected to the output of the acoustic wave sensing module and is used to perform primary amplification of the analog electrical signal.

[0138] A bandpass filter (not shown in the figure) has its input connected to the output of a preamplifier. Its center frequency is matched with the carrier frequency of the encoded acoustic signal and is used to filter out out-of-band noise.

[0139] The impedance transformation circuit (not shown in the figure) uses a voltage follower. The non-inverting input is connected to the output of the bandpass filter, and the output is used as the output of the signal conditioning module to convert the high output impedance to the low output impedance.

[0140] The decoding chip has its signal input pin connected to the output of the impedance transformation circuit. It is used to decode the conditioned analog electrical signal. The decoding chip integrates a programmable gain amplifier, envelope detector, data slicer, clock recovery circuit and decoder. It is used to perform signal amplification, filtering, digitization, synchronization and decoding operations. After the decoding verification is successful, it outputs a wake-up interrupt to the main control unit (MCU, specifically MSP430G2553IPW28) through the interrupt output pin.

[0141] X1 connects to the clock input and clock output pins of the decoding chip, with C5 and C10 connected in parallel as load capacitors (to match the oscillation characteristics of the crystal oscillator). It provides a high-precision clock reference for the digital signal processing circuitry of the decoding chip. The decoding chip requires a stable clock to ensure carrier synchronization during demodulation, bit synchronization during decoding, and timing control of internal logic, such as interrupt triggering and data buffering.

[0142] X2 connects to the MCU's clock input and clock output pins, providing clock hold (LPM3 mode) for the MSP430 in low-power mode. As an ultra-low-power MCU, the MSP430 enters low-power mode in standby mode, where the main clock is turned off, and only the 32.768kHz crystal oscillator is retained as the clock source, significantly reducing power consumption and making it suitable for battery-powered acoustic wave sensing devices.

[0143] The overall structure of the second decoding circuit includes an ultrasonic sensing module, a core decoding chip module, and an MCU main control module.

[0144] The ultrasonic sensing module uses a piezoelectric ultrasonic receiver. The signal conditioning and impedance matching unit uses an operational amplifier to form a non-inverting amplifier circuit as a preamplifier, with a gain set to 20-40dB to amplify millivolt-level signals to the hundreds of millivolt level or higher. The bandpass filter uses an active filter with a center frequency of 40kHz and a bandwidth of ±2kHz to ±5kHz to suppress out-of-band noise. The impedance transformation circuit uses a voltage follower, whose low-impedance output signal is directly connected to the channel input pin of the decoding chip (e.g., LFRX1).

[0145] The core decoding module of the decoding chip uses a single decoding chip. The main control module uses an ultra-low-power microcontroller. After the system powers on, the main control module first configures the decoding chip via the SPI interface. The analog front-end inside the decoding chip receives the analog electrical signal from the acoustic probe. This signal is first further amplified by a programmable gain amplifier, the gain of which is set by a configuration register to ensure that the signal amplitude reaches the optimal processing level. The processed analog signal is sent to an amplitude demodulator, the core of which is an envelope detector used to extract the envelope of the ASK modulated signal (i.e., the baseband digital signal). This envelope signal is then processed by an internal data slicer, which converts the analog envelope signal into a clear digital bitstream signal by comparing it with a programmable sensitivity threshold. The decoding chip detects a specific preamble. This preamble is usually an alternating sequence of '0's and '1's (e.g., "0xAA" or "0x55" in Manchester encoding), which serves to achieve bit synchronization and provide a stable clock reference for subsequent data decoding.

[0146] After clock recovery and locking, the digital bitstream is fed into the chip's built-in decoder. This decoder supports Manchester decoding and bidirectional phase decoding modes, selectable via register configuration. The decoder decodes the serial bitstream into parallel data bytes according to the encoding rules. The decoded data is temporarily stored in an internal buffer. The decoding chip compares the received data with a preset wake-up mode (typically a specific code of one or more bytes). The chip considers a received data frame a valid signal only if it contains the complete and correct wake-up mode.

[0147] After successful verification, an interrupt signal is triggered and the data register is prepared. The awakened master control module then communicates with the decoding chip through the SPI interface. First, it reads the interrupt status register to determine the source of the interrupt, and then reads the entire successfully decoded data frame from the data register in sequence.

[0148] The second decoding circuit processes the encoded acoustic signal as follows:

[0149] The received analog acoustic signal is sequentially amplified by programmable gain and then bandpass filtered.

[0150] Envelope detection is performed on the filtered signal to extract the baseband envelope signal;

[0151] The baseband envelope signal is compared with a threshold and converted into a digital bit stream.

[0152] The preamble is detected from the digital bit stream, and the clock signal synchronized with the transmitter is reconstructed from it.

[0153] The reconstructed clock signal is used to decode the digital bit stream following the preamble to obtain the decoded data.

[0154] The decoding chip is equipped with a register for storing a preset wake-up code. The mode code portion of the decoded data is compared with the preset wake-up code. Specifically, the decoded one-byte or multi-byte mode code sequence is matched bit by bit with the wake-up code stored in the register.

[0155] The decoding chip has an interrupt output pin, which is used to output a valid level signal as a wake-up interrupt to the main control unit when the mode code verification is consistent.

[0156] The main control unit connects to the decoding chip via an SPI interface or an I²C interface, and is used to read the decoded data containing unique identification information from the data register of the decoding chip after responding to a wake-up interrupt.

[0157] Specifically, the decoding process of the second decoding chip is as follows:

[0158] Step S1: Analog Signal Processing and Digitization

[0159] The analog front-end inside the decoding chip receives the analog electrical signal from the signal conditioning unit. This signal is first further amplified by a programmable gain amplifier (PGA), the gain of which is set by a configuration register to ensure the signal amplitude reaches the optimal processing level. Subsequently, the amplified signal passes through a bandpass filter, whose center frequency and bandwidth are configured in the register, to further filter out out-of-band interference. The processed analog signal is then fed into an amplitude demodulator, the core of which is an envelope detector used to extract the envelope of the ASK modulated signal (i.e., the baseband digital signal). This envelope signal is then processed by an internal data slicer, which converts the analog envelope signal into a clear digital bitstream signal by comparing it with a programmable sensitivity threshold.

[0160] Step S2: Clock Recovery and Data Synchronization

[0161] The decoding chip contains a clock recovery circuit that reconstructs a clock signal synchronized with the data rate of the transmitting end from the digital bitstream obtained in step S1. When the clock recovery circuit locks the input signal, the decoding chip detects a specific preamble. This preamble is typically an alternating sequence of '0's and '1's (e.g., "0xAA" or "0x55" in Manchester encoding), which serves to achieve bit synchronization and provide a stable clock reference for subsequent data decoding.

[0162] Step S3: Data Decoding and Frame Verification

[0163] After clock recovery and locking, the digital bitstream is fed into the chip's built-in decoder. This decoder supports Manchester decoding and bidirectional phase decoding modes, selectable via register configuration. The decoder decodes the serial bitstream into parallel data bytes according to the encoding rules.

[0164] Manchester decoding: Each bit has a level transition in the middle. '0' is represented by "01" (low to high transition), and '1' is represented by "10" (high to low transition). The decoder identifies data by detecting the level transitions in the middle of the bits. This method effectively eliminates DC offset and facilitates clock recovery.

[0165] Bidirectional phase decoding: A level transition at the beginning of a bit indicates '1', and no transition indicates '0'.

[0166] The decoded data is temporarily stored in an internal buffer. The decoding chip compares the received data with a preset wake-up mode (in this embodiment, a specific code of one or more bytes). The chip considers it a valid signal only if the received data frame contains a complete and correct wake-up mode.

[0167] Step S4: Interrupt Trigger and Data Output

[0168] Once a valid wake-up mode is successfully verified in step S3, the core decoding unit of the decoding chip will immediately set its interrupt output pin to the active state. This interrupt signal is sent directly to the interrupt pin of the main control unit, waking it up from sleep mode.

[0169] The awakened master control unit then communicates with the decoding chip via the SPI (or I²C) interface. It first reads the interrupt status register to determine the interrupt source (e.g., "data ready"), and then sequentially reads the entire successfully decoded data frame from the data register. This data frame, in addition to the wake-up code, typically contains subsequent commands or information data.

[0170] After reading and processing the data, the main control unit clears the interrupt flag by writing a command to a specific register of the decoding chip, thus restoring the / INT pin to an invalid state. Subsequently, the main control unit can re-enter sleep mode, and the entire system returns to a low-power monitoring state, awaiting the next valid ultrasonic signal.

[0171] In this embodiment, the first decoding circuit in the base station and the second decoding circuit in the tag adopt similar core hardware architectures, both based on the low-frequency wake-up receiving chip of the decoding chip. However, through differentiated peripheral configurations and software working modes, they are adapted to the functional requirements of the base station and the tag, respectively.

[0172] Specifically, the first decoding circuit of the base station also centers on a single decoding chip. Its signal input pins are directly connected to the base station's first acoustic receiver (e.g., an ultrasonic receiver probe) via a simple RC coupling and impedance matching network. Unlike the tag side, the discrete high-gain preamplifier and active bandpass filter are omitted here; instead, signal conditioning is achieved using the programmable gain amplifier (PGA) and configurable bandpass filter integrated within the decoding chip. Functionally, the key to the first decoding circuit lies in setting the decoding chip's operating mode. The base station's second main control unit configures the decoding chip's registers, either by setting or enabling specific "wake-up mode code" comparisons. The chip is placed in direct output mode, where its core decoding functions (envelope detection, clock recovery, and data decoding) continue to operate, but the decoded raw data stream (containing preamble, mode code, and tag ID data) is directly stored in the data buffer without triggering internal wake-up logic.

[0173] The chip is set to normal operating mode instead of low-power monitoring mode. Accordingly, its interrupt output pin ( / INT) does not need to be connected to the main control unit's interrupt pin. The base station's main control unit polls the decoding chip's status register periodically via SPI communication, actively reading the decoding results from its data buffer to obtain the tag's unique identification information. Finally, the distance between the tag and the base station is calculated by the time difference between the two initial electromagnetic and ultrasonic waves paired with the ID.

[0174] Furthermore, based on Figure 6 The decoding process of the second decoding circuit is as follows:

[0175] After the signal is input, it is split into two paths, which are amplified by channel amplifier 1 / 2 respectively. Each path simultaneously performs received signal strength measurement and status detection, with the specific status being "idle" or "normal". Then, the optimal channel signal is selected by the channel selector and enters the wake-up detection module to determine whether the "wake-up condition" is met. If it is not met, the detection continues in a loop. If it is met, it enters the main logic. The main logic interacts with the external MCU through SPI communication and performs envelope detection (specifically, extracting the baseband envelope of the ASK signal) and data slicing (specifically, converting the analog envelope into a digital bit stream) on the signal. The processed digital signal is sent to the Manchester decoder to complete decoding and clock recovery. The decoded data is then processed by the correlator for "correlation sequence calculation" (specifically, matching the preset wake-up mode) and "peak detection" (specifically, verifying data integrity), and finally outputs the decoding result.

[0176] In the field of container networking, containers circulate globally. If smart information tags could record relevant circulation information and internal environmental parameters, and be remotely monitored and managed, it could significantly improve logistics management efficiency and enhance the safety management of hazardous materials. However, due to the difficulty of charging during logistics, ensuring continuous power supply over a circulation cycle of several months has always been the biggest challenge in container networking solutions. Currently, the market either uses expensive cold chain logistics technology or ordinary containers with passive RF tags that can only perform simple identification and management. There is no more economical sensor tag technology for ordinary standard containers, which account for the majority of the market and reach tens of millions of containers. The core issue is the lack of an effective power management solution.

[0177] To address this, this application proposes a power management scheme that combines multi-tag positioning. The decoding chip in the second decoding circuit is equipped with a frequency detector and a mode correlator, and a dual wake-up mechanism is achieved through the following method:

[0178] The frequency detector is used to perform frequency domain analysis on the received signal. When the signal meets the preset frequency characteristics, a first-level wake-up trigger signal is generated.

[0179] The mode correlator is used to receive the first-level wake-up trigger signal and perform mode matching; if the mode matching is successful, the system wake-up is triggered directly; if the mode matching fails, the event is marked as a false wake-up and the false wake-up event information is written to the false wake-up register.

[0180] The main control unit is also used to read the information in the false wake-up register and adjust the detection parameters of the second decoding circuit based on the characteristics of the false wake-up event. The detection parameters include the frequency threshold of the frequency detector.

[0181] Specifically, the system's input signal comes from external signals received by the antenna and first enters the frequency detector. The frequency detector performs frequency domain analysis on the signal and generates a Wakeup Level 1 signal, which is the first level of coarse-grained wakeup trigger condition used to filter out signals that may need to be woken up.

[0182] The output of the frequency detector (wakeup level 1) is passed to the pattern correlator for a second-level fine-grained pattern matching (such as detecting the coding pattern of the signal, pulse sequence, and other predefined features): If the pattern matching is successful: the pattern correlator outputs a wakeup level 2 signal, directly triggering the system's wakeup action to complete a valid wakeup; if the pattern matching fails: the pattern correlator outputs an unsuccessful pattern correlation signal, marking this event as a false wakeup and writing it into the false wakeup register for later analysis of the cause of the false wakeup.

[0183] The microcontroller is responsible for handling false wake-ups and optimizing the detection logic. The microcontroller obtains detailed information about false wake-up events from the false wake-up register by reading the false wake-up register register. Based on the false wake-up records, the microcontroller generates a change setting to eliminate false wake-up events instruction and sends it to the register setting module.

[0184] After receiving instructions from the microcontroller, the register setting module adjusts the parameters of its internal configuration registers, such as the frequency threshold of the frequency detector, to avoid misinterpreting signals of non-target frequencies as wake-up signals. The adjusted parameters are then fed back to the frequency detector and the mode correlator to directly optimize the subsequent frequency detection and mode matching process, thereby reducing false wake-ups from the source.

[0185] This application also proposes a multi-tag identification method for acoustic localization, based on the aforementioned multi-tag identification system for acoustic localization, which includes the following steps:

[0186] B1: The base station sends an acoustic wake-up signal containing a specific wake-up mode code to the target tag;

[0187] B2: The tag receives the acoustic wake-up signal, decodes the acoustic wake-up signal, and generates a wake-up interrupt to activate from the sleep state when the identified pattern code matches a preset value;

[0188] B3: The activated tag sends a first radio frequency signal and an acoustic positioning signal containing its own unique identification information;

[0189] B4: The base station receives the first radio frequency signal and the acoustic positioning signal, and calculates the distance between the tag and the base station based on the time difference between their arrival.

[0190] In another embodiment, the wake-up function is not required; the tag can simply send a signal to the base station in one direction to achieve tag positioning.

[0191] An acoustic positioning multi-tag identification system includes a base station and at least one tag;

[0192] The tag includes a first main control unit, and a radio frequency transmission module and an acoustic wave transmission module, both connected to the first main control unit. The first main control unit is configured to control the radio frequency transmission module to send a radio frequency signal containing the tag's unique identification code, and to control the acoustic wave transmission module to send an acoustic wave signal modulated by digital encoding. The data frame structure of the acoustic wave signal includes at least a carrier wave, a preamble, a mode code, and data content.

[0193] The base station includes a second main control unit, and a radio frequency receiving module and an acoustic wave receiving module, both of which are connected to the second main control unit.

[0194] The acoustic wave receiving module includes an acoustic wave receiving probe and an acoustic wave decoding circuit; the acoustic wave receiving probe is used to receive acoustic wave signals and convert them into analog electrical signals; the acoustic wave decoding circuit is configured to perform envelope detection and digital slicing processing on the analog electrical signals to extract digital bit streams.

[0195] The acoustic decoding circuit is further configured to activate the second main control unit when a preset matching code is identified from the digital bit stream; it should be noted that the acoustic decoding circuit of this embodiment can adopt the first decoding circuit mentioned in the previous embodiment.

[0196] The second main control unit is configured to read the data content in the acoustic signal and calculate the distance between the tag and the base station based on the time difference of arrival of the radio frequency signal and the acoustic signal.

[0197] The data frame structure of the acoustic signal includes, in sequence, a carrier wave, a preamble, a mode code, and data content. The data content contains the unique identification code of the tag. The acoustic decoding circuit includes a programmable gain amplifier, a bandpass filter, and an envelope detector connected in sequence. The programmable gain amplifier is used to amplify the analog electrical signal, and the center frequency of the bandpass filter is matched with the carrier frequency of the acoustic signal.

[0198] The acoustic wave decoding circuit is a dedicated integrated circuit chip integrating a programmable gain amplifier, an envelope detector, a clock recovery circuit, and a decoder. The acoustic wave decoding circuit is equipped with a register for storing preset wake-up modes. The acoustic wave decoding circuit is configured to compare the extracted mode code with the preset wake-up mode in the register, and output a wake-up signal when they match. The second main control unit is configured as follows:

[0199] Extract the unique identification code of the tag from the data content of the sound wave signal;

[0200] The identification code obtained from the radio frequency signal is paired and verified with the identification code extracted from the sound wave signal;

[0201] Distance calculation based on the time difference of arrival is performed only when a pairing is successful.

[0202] This application also proposes a multi-tag identification method for acoustic positioning, based on the aforementioned multi-tag identification system for acoustic positioning, the method comprising:

[0203] A1: The tag synchronously transmits a radio frequency signal containing its unique identification code and a digitally encoded and modulated acoustic signal. The data frame structure of the acoustic signal includes at least a carrier wave, a preamble, a mode code, and data content.

[0204] A2: The acoustic wave signal is received by the acoustic wave receiving probe of the base station and converted into an analog electrical signal;

[0205] A3: The base station's acoustic decoding circuit performs envelope detection and digital slicing processing on the analog electrical signal to extract the digital bit stream, and activates the base station's main control unit when a preset matching code is identified from the digital bit stream.

[0206] A4: The main control unit of the activated base station reads the identification code from the acoustic signal data content and calculates the distance between the tag and the base station based on the arrival time difference between the radio frequency signal and the acoustic signal.

[0207] This application also proposes an application of a low-frequency wake-up receiving chip in the aforementioned acoustic wave positioning multi-tag identification system. The low-frequency wake-up receiving chip is a decoding chip or a chip compatible with it. The application includes: inputting the analog acoustic wave electrical signal converted by the acoustic wave receiving probe to the input terminal of the low-frequency wake-up receiving chip; using the envelope detection circuit and digital decoding circuit inside the low-frequency wake-up receiving chip to demodulate and perform pattern recognition on the analog acoustic wave electrical signal; and when a preset acoustic wave wake-up mode code is identified, triggering an interrupt in the positioning system main control unit using the wake-up output pin of the low-frequency wake-up receiving chip.

Claims

1. A sound wave localization multi-tag identification and wake-up system, characterized in that, Includes a base station and at least one tag: Base stations include: A first acoustic transmitter is used to transmit a first coded acoustic signal to the tag; A first radio frequency transmitter is used to send a first radio frequency signal containing the unique identification information of the base station to the tag; The first encoding modulation circuit has an input terminal connected to a basic carrier signal and an encoding control signal, and an output terminal connected to a second acoustic wave transmitter. It is used to modulate the unique identification information of the base station onto the basic carrier signal according to a preset frame structure. The frame structure of the first encoded acoustic wave signal includes a preamble for signal synchronization, a mode code for triggering wake-up, and data content containing the unique identification information of the base station. A first acoustic receiver is used to receive a second coded acoustic signal from the tag; The first decoding circuit is used to decode the received second coded acoustic signal and extract the unique identification information of the tag; The first main control unit is used to read the unique identification information of the tag extracted by the first decoding circuit and to pair and verify it with the unique identification information in the received second radio frequency signal. For tags that are successfully paired, the distance between the tag and the base station is calculated based on the time difference between the arrival of the second coded acoustic wave signal and the second radio frequency signal at the base station. Tags include: The second acoustic receiver is used to receive the first coded acoustic signal sent by the base station; The second decoding circuit is used to decode the first coded acoustic signal and generate a wake-up interrupt when the decoded pattern code matches the preset wake-up code in the tag through a wake-up detection mechanism. The second acoustic transmitter is used to send a second coded acoustic signal to the base station after the tag is woken up; The second radio frequency transmitter is used to synchronously transmit a second radio frequency signal containing the tag's unique identification information; The second encoding modulation circuit has an input terminal connected to the basic carrier signal and the encoding control signal, and an output terminal connected to the first acoustic wave transmitter. It is used to modulate the unique identification information of the tag onto the basic carrier signal according to a preset frame structure. The frame structure of the second encoded acoustic wave signal includes at least a preamble for signal synchronization and data content containing the unique identification information of the tag. The second main control unit, in response to a wake-up interrupt, controls the tag to wake up from its sleep state and controls the second acoustic transmitter and the second radio frequency transmitter to send the second coded acoustic signal and the second radio frequency signal.

2. The acoustic positioning multi-tag identification and wake-up system according to claim 1, characterized in that, The encoding and modulation circuit includes: The signal shaping link consists of multiple inverters connected in series. The input terminal receives the encoding control signal, which is used to invert and delay the signal. The modulation core circuit includes a differential pair module and a current mirror module; The differential pair module is composed of an NPN transistor and a PNP transistor connected in a complementary manner. Its first input terminal is connected to the output signal of the signal shaping link, and its second input terminal is connected to the fundamental carrier signal. The current mirror module is connected to the power supply path of the differential pair module to provide operating current to the differential pair module; The processed encoded control signal output from the signal shaping link is used to control the conduction state of the complementary transistors in the differential pair module, so that the basic carrier signal is selected or its amplitude is changed according to the logic level of the encoded control signal. The output of the modulation core circuit outputs the carrier signal processed by the differential pair module, which serves as the encoded acoustic signal.

3. The acoustic positioning multi-tag identification and wake-up system according to claim 1, characterized in that, The acoustic decoding circuit includes: The acoustic wave sensing module uses a piezoelectric ultrasonic receiver to convert the received coded acoustic wave signal into an analog electrical signal. The signal conditioning module, electrically connected to the output of the acoustic wave sensing module, is used to amplify, filter, and transform the analog electrical signal. The signal conditioning module includes: The preamplifier uses an operational amplifier to form a non-inverting amplifier circuit. Its non-inverting input is connected to the output of the acoustic wave sensing module to perform primary amplification of the analog electrical signal. A bandpass filter, whose input is connected to the output of a preamplifier, has a center frequency that matches the carrier frequency of the encoded acoustic signal and is used to filter out out-of-band noise. The impedance transformation circuit uses a voltage follower. The non-inverting input is connected to the output of the bandpass filter, and the output is used as the output of the signal conditioning module to convert high output impedance to low output impedance. The decoding chip has its signal input pin connected to the output of the impedance transformation circuit. It is used to decode the conditioned analog electrical signal. The decoding chip integrates a programmable gain amplifier, envelope detector, data slicer, clock recovery circuit and decoder. It is used to perform signal amplification, filtering, digitization, synchronization and decoding operations. After the decoding verification is successful, it outputs a wake-up interrupt to the main control unit through the interrupt output pin.

4. The acoustic positioning multi-tag identification and wake-up system according to claim 1, characterized in that, The decoding circuit processes the encoded acoustic signal as follows: The received analog acoustic signal is sequentially amplified by programmable gain and then bandpass filtered. Envelope detection is performed on the filtered signal to extract the baseband envelope signal; The baseband envelope signal is compared with a threshold and converted into a digital bit stream. The preamble is detected from the digital bit stream and used to reconstruct the clock signal synchronized with the transmitter. The reconstructed clock signal is used to decode the digital bit stream following the preamble to obtain the decoded data.

5. A method for acoustic wave localization, multi-tag identification, and wake-up, characterized in that, The acoustic positioning multi-tag identification and wake-up system based on any one of claims 1-4 includes the following steps: B1: The base station sends an acoustic wake-up signal containing a specific wake-up mode code to the target tag; B2: The tag receives the acoustic wake-up signal, decodes the acoustic wake-up signal, and generates a wake-up interrupt to activate from the sleep state when the identified pattern code matches a preset value; B3: The activated tag sends a first radio frequency signal and an acoustic positioning signal containing its own unique identification information; B4: The base station receives the first radio frequency signal and the acoustic positioning signal, and calculates the distance between the tag and the base station based on the time difference between their arrival.

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