CN112152728A - Convenient ultrasonic multi-path receiving and transmitting hardware system for behavior perception - Google Patents

Abstract

A convenient ultrasonic multi-path transceiving hardware system facing behavior perception comprises a USB synchronous transceiving sound card, a platform with an operating system, an ultrasonic generating sound and a microphone array; the USB synchronous receiving and transmitting sound card comprises circuits such as an MCU (microprogrammed control Unit), a TXCO (transmitter-receiver-co), a USB (universal serial bus), an audio DAC (digital-to-analog converter), a low-noise LDO (low dropout regulator), a microphone interface and the like, can be accessed to a USB interface of a platform with an operating system and is identified as a USB audio playing and recording device, and the USB audio driving is controlled by an upper computer program to realize the receiving and transmitting of a self-defined; the ultrasonic sound generating device comprises a linear power supply, a signal impact protection and energy saving circuit, a broadband power amplification circuit and an aluminum strip type high pitch loudspeaker, wherein an output signal of a sound card is amplified by the power amplification circuit and pushes the loudspeaker to emit ultrasonic sound; the microphone array is an array formed by 1-4 MEMS digital microphones capable of acquiring ultrasonic frequency bands. The system is low in cost and good in universality, can be conveniently controlled, and can realize multichannel synchronous receiving and transmitting of any ultrasonic signal in a 20K-40KHz frequency band.

Description

Convenient ultrasonic multi-path receiving and transmitting hardware system for behavior perception

Technical Field

The invention belongs to the technical field of electronic circuits and signal systems, relates to a supporting platform for application research such as behavior perception by utilizing ultrasonic signals, and particularly relates to a convenient ultrasonic multipath transceiving hardware system for behavior perception.

Background

In recent years, a new leading-edge research hotspot, namely 'wireless perception', is generated, the wireless perception technology mainly carries out non-contact behavior perception on people through universal wireless signals, such as RF, WiFi, ultrasonic waves and the like, the signals are not influenced by light line elements, privacy is not snooped, the wireless perception technology can be applied to health monitoring, novel human-computer interaction, behavior identification and the like, and the wireless perception technology is widely concerned and valued by academia and the industry. The ultrasonic wave has the advantages of no radiation, easy acquisition, no influence of environmental noise, light, object color and the like, no privacy snooping, capability of ensuring the safety of human eyes compared with laser and infrared, and the like. Therefore, in recent years, some famous wireless sensing research teams at home and abroad use ultrasonic waves to perform some high-precision and practical-value studies on behavior sensing, such as: human respiration monitoring, gait recognition, gesture recognition, trajectory tracking, fall detection, intrusion detection and the like.

At present, the ultrasonic wave transceiving hardware platform facing behavior perception can be divided into two types of commercial equipment and self-made equipment, but all have various defects. Commercial equipment comprises intelligent mobile equipment (such as a PC, a smart phone, a watch and the like) and sound microphone equipment, the commercial equipment generally does not directly have high sampling rate and the transceiving capacity of an ultrasonic frequency band, the universality is not good at present, a general researcher can utilize the frequency band of 18-22KHz, according to related research, partial infants and children can hear ultrasonic waves slightly higher than 20KHz, and the potential danger of interfering the children when the commercial equipment is applied to homes is shown. According to the related data, the hearing range of some livestock is higher than that of human (the upper limit of cattle hearing is about 35KHz, the upper limit of sheep hearing is about 30KHz, and the hearing range of horses is about 25KHz), so that the current commercial equipment cannot be applied to livestock. Furthermore, these commercial devices cannot flexibly implement mimo and mlrs, and some require even long-time software to correct sampling frequency offset. On the other hand, the piezoelectric ultrasonic transducer adopted by the existing self-made equipment can only send fixed frequency, the hardware cost for realizing frequency modulation is very high, even the piezoelectric ultrasonic transducer can be driven by high voltage, the beam angle and the sensitivity are very small, and the sensing range is limited.

Disclosure of Invention

In order to overcome the defects of the prior art and further widen the application range of behavior sensing based on ultrasound, the invention aims to provide a convenient ultrasound multipath transceiving hardware system facing the behavior sensing, which can design the transmitted ultrasound signals at will in the frequency band of 20K-40KHz and can receive the signals; secondly, can assemble and combine host program to realize multichannel or the ultrasonic signal of one way receiving and dispatching in a flexible way, be that one kind control is convenient, the frequency bandwidth, can realize that the supersound is sent more and is received more and receive synchronous hardware platform.

In order to achieve the purpose, the invention adopts the technical scheme that:

a convenient ultrasound multiplex transceiving hardware system oriented to behavioral awareness, comprising:

the microphone array is an array formed by 1-4 MEMS digital microphones capable of acquiring ultrasonic frequency bands;

the USB synchronous receiving and transmitting sound card comprises a microcontroller, a crystal oscillator, a USB communication circuit, an audio DAC, a low-noise LDO (low dropout regulator) and a microphone interface, wherein the microphone array is connected with the USB synchronous receiving and transmitting sound card through the microphone interface to realize single receiving or multiple receiving;

a USB interface of the platform with an operating system is connected with a USB synchronous receiving and transmitting sound card through a USB communication line, and the USB synchronous receiving and transmitting sound card is identified as USB audio playing and recording equipment;

the sound is taken place to supersound is connected with the synchronous receiving and dispatching sound card of USB through the audio line, including linear power supply, signal impact protection and energy-conserving circuit, wide band power amplifier circuit and speaker, the synchronous receiving and dispatching sound card output signal of USB promotes the speaker after wide band power amplifier circuit power amplification and sends the sound wave, the synchronous receiving and dispatching sound card of USB adopts the audio line that divides two monophones to connect two supersound and takes place the sound to realize singly sending or independently two.

Preferably, each MEMS digital microphone is a PCB platelet with an L channel or an R channel, and the real-time synchronous acquisition of the sound wave data stream of 1-4 channels is realized by combining two types of MEMS digital microphones with an L channel and an R channel and accessing to a microphone interface on the USB synchronous transceiving sound card.

Preferably, the microphone array is a double-microphone or four-microphone array mode, after the L/R microphone small plate is correspondingly connected to the microphone interface, a toggle switch on the USB synchronous transceiving sound card is switched and then is inserted into a platform with an operating system, and the conversion of the two modes is realized; the microphone interfaces are 4 FPC interfaces, an SAI A module arranged outside an SAI1 is used as a master mode, an SAI B module is used as a slave mode, I2S led out by the SAI A is connected to No. 1 and No. 3 FPC interfaces, I2S led out by the SAI B is connected to No. 2 and No. 4 FPC interfaces, and two interfaces of the same module are connected to two different PCB small plates of an L sound channel and an R sound channel; 1-2 wheat are accessed to realize single/double channel acquisition in a double-wheat array mode, and 1-4 wheat are accessed to realize 1-4 channel acquisition in a four-wheat array mode.

Preferably, the USB synchronous transceiver sound card adopts an STM32F4/F7xx high-performance microcontroller chip which takes ARM Cortex M4/M7 as an inner core as a main control processor, a 24.576MHz external high-precision active crystal oscillator with temperature compensation is adopted as a controller clock source, and a control key, a state monitoring indicator lamp for playing and recording audio data streams and an external interface are arranged at the periphery of the controller clock source; the USB communication circuit is designed by a USB _ OTG _ FS peripheral in an STM32 chip, an audio DAC adopts an ES9023 stereo audio digital-to-analog conversion chip, and is connected with an ES9023 through an I2S peripheral interface in an STM32 chip, so that decoding and output of audio data stream signals are realized; each circuit of the USB synchronous receiving and transmitting sound card adopts 3.3V voltage, namely, VBUS of the USB communication circuit is converted into 3.3V by adopting a low-noise LDO, and a microphone interface is a four-way interface expanded by an SAI peripheral A module and a B module in an STM32 chip and matched with a timer.

Preferably, the USB synchronous transceiving sound card only uses one clock source to ensure transceiving synchronization on hardware.

Preferably, in the USB synchronous transceiving sound card, an external high-speed clock is provided by a crystal oscillator of 24.576MHz, the external high-speed clock of 24.576MHz is finally distributed to an SAI peripheral 6.144MHz in a receiving mode by designing the distribution of an internal PLL and a clock tree of STM32, a bit clock frequency of 3.072MHz is provided to a digital microphone after frequency halving by a timer, and the bit clock frequency is distributed to an I2S peripheral 98.304MHz in a transmitting mode, so that MCLK of an audio DAC ES9023 finally connected to I2S is 24.576MHz, and further, both audio receiving and transmitting sampling rates are 96K.

Preferably, the operating system of the platform with the operating system is linux, Windows or macOS, when the platform with the operating system is connected with the USB synchronous transceiver sound card, the USB synchronous transceiver sound card is powered on and enumerated to identify the USB synchronous transceiver sound card as a USB audio device, the platform with the operating system serves as a host, the USB synchronous transceiver sound card serves as a slave, and the platform with the operating system is designed with an upper computer program to control the API driven by the USB audio device to further realize the output and input of audio data streams, so that the platform with the operating system realizes the related processing of signals.

Preferably, the ultrasonic sound generation device is provided with a 3.5mm audio signal input interface for connecting the output of a USB synchronous receiving and transmitting sound card, the interface is internally connected with the in-phase input end of a broadband power amplifier circuit and the input end of a voltage comparator of a signal impact protection and energy-saving circuit, a relay on the signal impact protection and energy-saving circuit determines the path of a linear power output and the broadband power amplifier circuit, and two ends of a loudspeaker are connected with the left sound channel output end of the broadband power amplifier circuit; the ultrasonic sound generation device has a frequency response range of 1K-40KHz and can send any sound wave signal in the frequency response range, the signal impact protection and energy saving circuit can prevent the loudspeaker from being damaged by large impact generated when the signal is suddenly input and disconnected, and the power amplifier circuit can be powered off and save energy when no sound source is input.

Preferably, the loudspeaker is an aluminum strip type high pitch loudspeaker with impedance of 8 omega and frequency response range up to 40KHz, the broadband power amplifier circuit adopts a single-track power amplifier circuit with a class-A LM4766 integrated power amplifier chip as a core, and the function of adjusting 1/2/4/8/16W five-grade output power is set by switching the resistance value of a feedback resistor; the linear power supply adopts a 220V alternating current input 120W and 18V double-output annular transformer with a middle tap; the signal impact protection and energy saving circuit mainly comprises an STM32F031F6P6MCU, a voltage comparator, three relays, a control key and a state indicator lamp, wherein the voltage comparator monitors an input signal in real time, namely a sound source signal decoded and output by a sound card, the voltage comparator monitors the sound source input, then external interruption is started and pulse counting is started, the three relays are started after the sound source input is monitored, and a path from a linear power supply to a broadband power amplifier circuit is opened to enable the power amplifier and the loudspeaker to be electrified and operated.

Preferably, a 60-degree temperature control switch and a cooling fan are adopted in the ultrasonic sound generation device, and the temperature control switch is fixed on a cooling fin of the broadband power amplifier circuit, so that over-temperature and timely cooling of the power amplifier chip is achieved.

Compared with the existing platform, the invention takes audio equipment such as a sound box, a sound card and the like as a designed reference prototype, designs a set of novel broadband ultrasonic transceiving system, can send any ultrasonic signal in a broadband of 20K-40KHz under a sampling rate of 96K, can synchronously receive the signal, and can realize multichannel independent and synchronous multiple sending and multiple receiving.

Drawings

Fig. 1 is a block diagram of the overall structure of the present invention.

FIG. 2 is a first schematic circuit diagram of a USB synchronous transceiver sound card of the present invention, wherein (a) is an MCU circuit diagram; (b) indicating a circuit diagram for the audio stream status; (c) is a TCXO circuit diagram; (d) is a key circuit diagram.

FIG. 3 is a second schematic circuit diagram of the USB synchronous transceiver sound card of the present invention, wherein (a) is a USB communication circuit diagram; (b) is an LDO circuit diagram; (c) is an audio DAC circuit diagram; (d) is a microphone interface circuit diagram.

Fig. 4 is a STM32 clock tree model design of the USB synchronous transceiver card of the present invention.

Fig. 5 is a structural view of an ultrasound generating sound of the present invention.

Fig. 6 is a schematic diagram of a wideband power amplifier circuit of ultrasonic sound generation of the present invention, wherein (a) is a power amplifier circuit of LM4766 monaural; (b) a toggle switch with adjustable output power for five gears, wherein (right side of the figure) a single small plate is shown; (c) is a rectification circuit diagram; (d) is a power interface circuit of a heat dissipation fan.

FIG. 7 is a schematic diagram of a signal impact protection and energy saving circuit of the ultrasonic sound generator of the present invention, wherein (a) is an MCU circuit diagram; (b) is an OSC circuit diagram; (c) indicating a circuit for the LED key; (d) is a voltage comparator circuit; (e) is an SWD/USART circuit; (f) a RESET circuit; (g) is a control key circuit; (h) a three-way relay circuit for the power amplifier power supply; (i) is an AC/DC circuit diagram.

Fig. 8 is a software flow chart of the signal impact protection and energy saving circuit of the ultrasonic sound generation device of the present invention.

Fig. 9 is a circuit diagram of the L and R channels of the microphone according to the present invention.

Fig. 10 is a schematic structural diagram of a two-transceiver and four-transceiver system according to the present invention.

Detailed Description

The embodiments of the present invention will be described in detail below with reference to the drawings and examples.

As shown in fig. 1 and 9, a convenient ultrasound multi-channel transceiving hardware system facing behavioral awareness includes: the system comprises four parts, namely a USB synchronous receiving and transmitting sound card 3, a platform 6 with an operating system, an ultrasonic generating sound 1 and a microphone array 2; the whole system is constructed in such a way that a USB synchronous receiving and transmitting sound card 3 is connected to a USB interface of a platform 6 with an operating system through a USB communication line 5 and identified as USB audio playing and recording equipment, a USB audio driver is controlled by an upper computer program to realize the receiving and transmitting of a user-defined ultrasonic signal, meanwhile, the USB synchronous receiving and transmitting sound card 3 is connected with an ultrasonic generating sound 1 through an audio line, a 3.5mm stereo is divided into two monaural audio lines to be connected with the two ultrasonic generating sound 1, so that the single transmitting or the independent two transmitting are realized, and finally, the USB synchronous receiving and transmitting sound card 3 is externally connected with a microphone array 2 to realize the single receiving or the 1-4 receiving.

As shown in fig. 2 (a) - (d) and fig. 3 (a) - (d), the USB synchronous transceiver card 3 mainly includes an STM32 MCU with an ARM Cortex M4/M7 as a core, a clock source, a USB communication circuit, an audio DAC, a low-noise LDO, and a microphone interface circuit. Specifically, as shown in the first schematic circuit diagram of the USB synchronous transceiving sound card shown in fig. 2, the sound card uses an STM32F4/F7xx high performance Micro Controller (MCU) chip as a main control processor, uses an external high precision active crystal oscillator (TCXO) with temperature compensation of 24.576MHz as an external high speed clock (HSE), and is provided with a control KEY (KEY), an audio stream status indicator for playing and recording, and other peripheral interfaces. As shown in a schematic diagram of a partial circuit of a USB synchronous transceiving sound card shown in fig. 3, a USB communication circuit of the sound card is designed by using a USB _ OTG _ FS peripheral device in an STM32 chip; the microphone interface circuit is designed by adopting the parameters of an MEMS digital microphone of a type of a Storey electronic SPH0641LU4H-1 which needs to be accessed by matching with the peripheral equipment of SAI 1; the audio DAC circuit is designed by adopting an ES9023 stereo audio digital-to-analog conversion chip with an I2S input interface, I2S in the STM32 is configured into a half-duplex master mode, the ES9023 is used as slave receiving, and the device is connected with the ES9023 through an I2S peripheral interface in the STM32, so that decoding and output of audio data stream signals are realized. The sound card adopts 3.3V voltage for each circuit, namely, the VBUS of the USB is converted into 3.3V by adopting low-noise LDO.

Specifically, the microphone adopts a Rogowski electronic SPH0641LU4H-1 type MEMS digital microphone, the frequency response upper limit of the microphone can reach 80KHz, the frequency range of the microphone which needs an external bit clock to work in an ultrasonic mode is 3.072 MHz-4.8 MHz, and the working voltage VDD is 1.62V-3.6V. The integrated Serial Audio Interface (SAI) on the chip STM32 allows the microcontroller to communicate with external audio equipment, the SAI comprising two independent sub-modules SAI a and SAI B that can operate synchronously or asynchronously, configuring the SAI a and B modules of the SAI1 peripheral in a master-slave synchronous mode, which is used as I2S with up to 4 pins (SD, SCK, FS, and MCLK) per audio sub-module. Firstly, the received audio sampling rate needs to be 96KHz, according to the size of a single slot of the frequency (FS _ a/B) of SAI SCK _ a/B, the number of slots of each slot can transmit audio data of one channel, a SAI a or B submodule is set to be respectively connected to L and R channel microphones, four channels of audio data are shared, that is, the number of slots is 4, the size of the single slot is set to be 16 bits, and therefore the SAI SCK _ a/B frequency needs to be 6.144 MHz. Since SAI is used to receive microphone PDM data without the need to provide the master clock MCLK, and the disable divider is set (both the master divider and the bit clock divider are off) according to the SAI clock generator architecture, MCLK _ a/B will have no output and SAI SCK _ a/B is equal to the peripheral clock SAI _ CK _ x that the system assigns to SAI, and thus SAI _ CK _ x also needs to be 6.144 MHz. In summary, as shown in the schematic circuit diagrams of fig. 2 and 3, the microphone interface is an interface that realizes 4 accessible digital microphone arrays by using the A, B module and the timer of the SAI1, and each interface is an FPC flexible flat cable interface.

In order to ensure the synchronization of transceiving on hardware, namely, the circuit design of the sound card only adopts one clock source, an external high speed clock (HSE) is provided by a TCXO with 24.576MHz, the HSE clock with 24.576MHz is finally distributed to an SAI peripheral 6.144MHz in a receiving mode by designing the distribution of an internal PLL and a clock tree of STM32, a bit clock frequency of 3.072MHz is provided to a digital microphone after frequency halving by a timer, the bit clock frequency is distributed to an I2S peripheral 98.304MHz in a transmitting mode, MCLK of an audio DAC ES9023 finally connected to I2S is 24.576MHz, and further, the sampling rates of audio transceiving and audio transmitting are both 96K. The synchronous clock MCLK required by the audio DAC is not provided by a separate crystal oscillator, but the MCO (master clock output) of I2S in the STM32 chip is turned on again to complete the connection of four lines of the master and slave, i.e., I2S _ CK (serial bit clock, serial clock output in master mode), I2S _ WS (frame clock for switching data of the left and right channels at a frequency equal to the sampling rate fs of the audio signal), I2S _ SD (serial data for transmitting data on two time-division multiplexed data channels), I2S _ MCK (master clock, which may be enabled or disabled), as shown in fig. 3.

As shown in fig. 4, the STM32 MCU as the master control core of the USB synchronous transceiver card 3 needs to strictly design a clock tree model. Since the upper limit of the system transceiving frequency response is to reach 40KHz, and the audio sampling frequency fs should be at least 96KHz according to the nyquist sampling theorem, taking the audio transmitting sampling frequency fs of 96KHz as the design target, it can be known that the frequency of I2S _ CK should be designed to be 3.072MHz according to the formula I2S _ CK being I2S _ ws (fs) 2 (channel number) 16(16bit, quantization bit width). In addition, when I2S is configured as the master mode, the clock frequency of I2S _ MCK outputted by the master clock is fixed to 256 × fs, i.e., 24.576MHz, and according to the design principle of one crystal oscillator clock as described above, the HSE also selects TCXO of 24.576 MHz.

The peripheral clock SAI _ CK _ x of SAI comes from the Q-divided output of PLLI2S, taking PLLI2S as an example, and the calculation formula is as follows:

SAI_CK_x＝(HSE/PLLI2SM)*PLLI2SN/PLLI2SQ/PLLI2SDIVQ

in order to make the received audio sampling rate fs be 96KHz and have no error, the PLLI2SM is set to 24, the PLLI2SN is set to 192, the PLLI2SQ is set to 8, and the PLLI2SDIVQ is set to 4, so that SAI _ CK _ x is 6.144MHz as required, as can be seen from the above, because the SAI internal frequency divider is disabled, the SAI SCK _ a/B frequency is also 6.144MHz (the frequency of the bit clock I2S _ CK-3.072 MHz required by the digital microphone), and after the frequency output pin of the SAI SCK _ a/B is connected to the timer again for frequency division, a synchronous bit clock of 3.072MHz can be synchronously provided for a plurality of microphones.

Further, the peripheral clock I2S _ CLK of I2S is I2S _ APB1 CLK, and the output from PLLI2S (divided by an R coefficient) requires calculation of the values of the respective dividers inside I2S according to designed fs. When I2S _ MCK output is enabled, the fs frequency calculation is as follows:

fs＝I2S_APB1 CLK/[256*(2*I2SDIV+ODD)]

wherein: I2S _ APB1 CLK (HSE/PLLI2SM) PLLI2SN/PLLI2 SR. HSE is 24.576MHz, where: PLLI2SM range: 2-63, and the value range of PLLI2SN is as follows: 192-432, and the value range of PLLI2SR is as follows: 2-7, the value range of I2SDIV is as follows: 2-255, ODD value range: 0/1. According to the above constraint conditions, in order to fix fs to 96KHz and realize 0 error without considering the TXCO frequency error, PLLI2SM is set to 24, PLLI2SN is set to 192, PLLI2SR is set to 2, I2SDIV is set to 2, ODD is set to 0, I2S _ APB1 CLK is set to 98.304MHz, and fs is set to 96 KHz.

The platform 6 with the operating system can be a platform based on operating systems such as linux, Windows or macOS, for example, an android smart phone, a computer, a raspberry group, and the like, the USB synchronous transceiver sound card 3 is connected to a USB interface of the platform 6, the sound card can be identified as a USB audio device after being powered on and enumerated, at this moment, the platform 6 serves as a host, the USB synchronous transceiver sound card 3 serves as a slave, and through designing an upper computer program on the platform, some APIs driven by the USB audio device are controlled to further realize output and input of audio data streams, so that related processing of signals can be realized on the platform.

As shown in fig. 5, a structure diagram of an ultrasonic sound generating device 1 is shown, which mainly comprises a loudspeaker 1-1, a broadband power amplifier circuit 1-8, a linear power supply 1-9, a signal impact protection and energy saving circuit 1-2, a sound housing 1-7, and the like, wherein the sound device is provided with a 3.5mm audio signal input interface 1-3 for connecting the output of a sound card, and is also provided with a heat radiation fan 1-6, the power supply of the heat radiation fan 1-6 is derived from the rectified voltage of the broadband power amplifier circuit, one branch of the power supply line of the heat radiation fan is provided with a normally open temperature control switch 1-4 with a 60-degree threshold, and the temperature control switch 1-4 is fixed on a heat radiation fin 1-5 of the broadband power amplifier circuit 1-8, so that the over-temperature monitoring and heat radiation of a power. The 3.5mm audio signal input interface 1-3 is internally connected with the non-inverting input end of the broadband power amplifier circuit 1-8 and the voltage comparator input end of the signal impact protection and energy saving circuit 1-2, a three-way relay on the signal impact protection and energy saving circuit 1-2 determines the path of the output of the linear power supply 1-9 and the broadband power amplifier circuit 1-8, and two ends of the loudspeaker 1-1 are connected with the left sound channel output end of the broadband power amplifier circuit 1-8. The linear power supply 1-9 is composed of a 120W, 18V double-output ring transformer and a power supply shell, and is provided with three paths of parallel output interfaces for simultaneously connecting three paths of sound equipment and supplying power to a broadband power amplification circuit 1-8 in the sound equipment, the sound equipment has the main function that weak analog signals output by a sound card are subjected to power amplification through the broadband power amplification circuit 1-8, a loudspeaker 1-1 is pushed to emit sound waves, the sound equipment has a frequency response range of 1K-40KHz and can send any sound wave signals in the frequency response range of the sound card, and the loudspeaker 1-1 adopts an aluminum belt type high pitch loudspeaker with impedance of 8 omega and frequency response range up to 40 KHz.

As shown in (a) to (d) of fig. 6, schematic diagrams of the broadband power amplifier circuit 1-8 of the ultrasound generating sound 1 are shown. The design of the broadband power amplifier circuit 1-8 needs to ensure broadband response and low distortion, a single-channel power amplifier circuit is designed by taking a class-A LM4766 integrated power amplifier chip as a core, and the function of 1/2/4/8/16W five-gear output power adjustment is set by switching the resistance value of a feedback resistor; the power supply of the power amplifier selects a linear power supply 1-9, a 120W and 18V double-output annular transformer with 220V alternating current input and a middle tap is adopted, the power supply voltage of the LM4766 is positive and negative direct current voltage of double 18V alternating current output from the linear power supply 1-9 after passing through a rectifying circuit, and an interface is also arranged to provide power for the cooling fans 1-6.

As shown in (a) to (i) of fig. 7, a schematic diagram of a signal impact protection and energy saving circuit 1-2 of the ultrasound generation sound 1 is shown. The signal impact protection and energy saving circuit 1-2 mainly comprises an STM32F031F6P6MCU, a voltage comparator, a power amplifier power supply, a three-way relay, an AC to DC, a control key, a state indicator lamp and other circuits.

The circuit uses STM32F031F6P6 as a main controller, and the signal that inputs wide band power amplifier circuit 1-8, namely the sound source signal of sound card decoding output, is monitored in real time through voltage comparator, sets up the threshold value of comparative voltage to be 200mV, and the transmission signal of input can trigger the comparator and constantly send the pulse wave, monitors the sound source input and then triggers MCU and produce the outside interrupt to the pulse count begins. The specific software working process is as shown in fig. 8, firstly, the MCU system is powered on and initialized, if the IO port connected to the output of the voltage comparator detects an external rising edge, the system is triggered to be interrupted externally, and then the pulse counting is started at the interrupt callback function, the main cycle polling detects that the number of pulses is 20, then the three relays are closed, the path from the linear power supply 1-9 to the broadband power amplifier circuit 1-8 is opened, so that the broadband power amplifier circuit 1-8 is powered on and operated, and the power amplifier power supply is first input and then delayed; meanwhile, when the system is initially powered on, the working time length needs to be manually set according to the sound wave emitting time length, the default time is 5min, once the system detects an input signal, the three relays are started and then timing is started, the relays are closed in advance when the timing is 4min50s, and the power amplifier and the loudspeaker 1-1 are powered off firstly. In practical use, the corresponding working time length is set by manually operating the two control keys (the plus-minus key) according to the sound wave emission time length set by the upper computer program, 5min is taken as an interval, if the sound wave emission time length set by the upper computer program is 10min, the power amplifier can be powered off in advance at 9min50s by only controlling to press the plus key, namely the power amplifier can be turned off in advance by 10s before the set working time length after the power amplifier is powered on by the system. This mechanism avoids the sudden input or disconnection of the source of sound when the power amplifier is in its fully operational state causing a large surge, which would appear as a strong plosive if it drives the loudspeaker 1-1, possibly damaging the tweeter 1-1. Therefore, the circuit can prevent the high pitch loudspeaker 1-1 from being damaged by large impact generated when signals are suddenly input and disconnected, and can also cut off the power of the broadband power amplifier circuit 1-8 when no sound source is input, thereby saving energy of class A power amplifiers with large quiescent current.

Each digital microphone is designed to be an L channel or an R channel, as shown in fig. 9, a circuit board structure and a circuit schematic diagram of the L and R channels of the microphone are shown, two PCB small boards of independent L/R channels are designed by connecting an L/R pin of the microphone to VDD or GND, and the two PCB small boards can be combined and accessed to a microphone interface of a USB synchronous transceiver card 3 by using an FPC flexible flat cable 4, so that real-time synchronous acquisition of sound wave data streams of 1-4 channels can be realized by combining with an upper computer program.

As shown in fig. 10, a schematic structural diagram of the two-transmitter four-receiver system of the present invention is shown, the whole system is constructed by connecting a USB synchronous transceiver sound card to a USB interface of a platform with an operating system through a USB communication line, and simultaneously, the USB synchronous transceiver sound card is connected to an ultrasonic sound generator through an audio line, and two ultrasonic sound generators can be connected by using a 3.5mm stereo or two monaural audio lines. The microphone array consists of 1-4 MEMS digital microphones of a type of Touhou electronic SPH0641LU4H-1 which can acquire ultrasonic frequency bands, a master control processor STM32 of a USB synchronous transceiving sound card, and a certain sub-module of SAI in a chip of the master control processor STM32 can only acquire data of two sound channels simultaneously, namely two interfaces led out by SAI A or SAI B can only be accessed into a microphone platelet of L and R by FPC (flexible printed circuit) flexible flat cables and can not be accessed into the same sub-module by the same sound channel, so that the array type of the microphone array can be flexibly arranged and designed according to the requirements of users. For example, the FPC interfaces 1 and 3 to which I2S led out from SAI a is connected, the FPC interfaces 2 and 4 to which I2S led out from SAI B is connected, and two interfaces of the same module need to be connected to two different microphone small boards, i.e., L and R; 1-2 wheat can be accessed to realize single/double channel collection in the double-wheat mode, 1-4 wheat can be accessed to realize 1-4 channel collection in the four-wheat mode, a toggle switch on a USB synchronous receiving and transmitting sound card is switched and then a platform with an operating system is inserted, and the conversion of the two modes is realized. The construction mode of the system can realize independent two-transmission four-reception at most, and in fact, a platform with an operating system generally has a plurality of USB interfaces or even a plurality of built-in USB controllers, and can extend USB hubs to access a plurality of USB synchronous receiving and transmitting sound cards so as to realize more multi-path receiving and transmitting.

The present invention is not limited to the above-described embodiments, which are intended to be illustrative only and not limiting; those skilled in the art, having the benefit of this disclosure, may effect numerous modifications thereto without departing from the scope and spirit of the invention as set forth in the claims that follow.

Claims (10)

1. A convenient ultrasonic multi-channel transceiving hardware system facing behavior perception is characterized by comprising:

the microphone array is an array formed by 1-4 MEMS digital microphones capable of acquiring ultrasonic frequency bands;

the USB synchronous receiving and transmitting sound card comprises a microcontroller, a clock source, a USB communication circuit, an audio DAC, a low-noise LDO (low dropout regulator) and a microphone interface, wherein the microphone array is connected with the USB synchronous receiving and transmitting sound card through the microphone interface to realize single receiving or multiple receiving;

a USB interface of the platform with an operating system is connected with a USB synchronous receiving and transmitting sound card through a USB communication line, and the USB synchronous receiving and transmitting sound card is identified as USB audio playing and recording equipment;

the sound is taken place to supersound is connected with the synchronous receiving and dispatching sound card of USB through the audio line, including linear power supply, signal impact protection and energy-conserving circuit, wide band power amplifier circuit and speaker, the synchronous receiving and dispatching sound card output signal of USB promotes the speaker after wide band power amplifier circuit power amplification and sends the sound wave, the synchronous receiving and dispatching sound card of USB adopts the audio line that divides two monophones to connect two supersound and takes place the sound to realize singly sending or independently two.

2. The convenient ultrasonic multi-channel transceiving hardware system oriented to behavior perception according to claim 1, wherein each MEMS digital microphone is a PCB (printed Circuit Board) small plate with an L channel or an R channel, and real-time synchronous acquisition of sound wave data streams of 1-4 channels is achieved by combining two MEMS digital microphones with the L channel and the R channel and connecting the two MEMS digital microphones to a microphone interface on a USB (Universal Serial bus) synchronous transceiving sound card.

3. The behavior perception-oriented convenient ultrasonic multi-path transceiving hardware system according to claim 2, wherein the microphone array is in a dual-microphone or four-microphone array mode, and after the L/R microphone platelet is correspondingly connected to a microphone interface, a toggle switch on the USB synchronous transceiving sound card is switched and then is inserted into a platform with an operating system, so that conversion of two modes is realized; the microphone interfaces are 4 FPC interfaces, an SAI A module arranged outside an SAI1 is used as a master mode, an SAI B module is used as a slave mode, I2S led out by the SAI A is connected to No. 1 and No. 3 FPC interfaces, I2S led out by the SAI B is connected to No. 2 and No. 4 FPC interfaces, and two interfaces of the same module are connected to two different PCB small plates of an L sound channel and an R sound channel; 1-2 wheat are accessed to realize single/double channel acquisition in a double-wheat array mode, and 1-4 wheat are accessed to realize 1-4 channel acquisition in a four-wheat array mode.

4. The convenient ultrasonic multi-path transceiving hardware system facing behavior perception according to claim 1, wherein the USB synchronous transceiving sound card employs an STM32F4/F7xx high performance microcontroller chip with ARM Cortex M4/M7 as an inner core as a main control processor, a 24.576MHz external high precision active crystal oscillator with temperature compensation is employed as a controller clock source, and a control key, a status monitoring indicator lamp for playing and recording audio data stream and an external interface are disposed at the periphery of the controller clock source; the USB communication circuit is designed by a USB _ OTG _ FS peripheral in an STM32 chip, an audio DAC adopts an ES9023 stereo audio digital-to-analog conversion chip, and is connected with an ES9023 through an I2S peripheral interface in an STM32 chip, so that decoding and output of audio data stream signals are realized; each circuit of the USB synchronous receiving and transmitting sound card adopts 3.3V voltage, namely, VBUS of the USB communication circuit is converted into 3.3V by adopting a low-noise LDO, and a microphone interface is a four-way interface expanded by an SAI peripheral A module and a B module in an STM32 chip and matched with a timer.

5. The convenient ultrasonic multi-path transceiving hardware system for behavior awareness according to claim 4, wherein the USB synchronous transceiving sound card only adopts one clock source to ensure transceiving synchronization on hardware.

6. The convenient ultrasonic multi-channel transceiving hardware system facing behavior perception according to claim 4, wherein in the USB synchronous transceiving sound card, an external high-speed clock is provided by a crystal oscillator of 24.576MHz, the external high-speed clock of 24.576MHz is finally distributed to the SAI peripheral device 6.144MHz in a receiving mode by designing distribution of an internal PLL and a clock tree of STM32, the bit clock frequency of 3.072MHz is provided for the digital microphone after frequency halving of a timer, the bit clock frequency is distributed to the I2S peripheral device 98.304MHz in a transmitting mode, MCLK of an audio DAC ES9023 finally connected to the I2S is 24.576MHz, and further, sampling rates of audio transceiving are both 96K.

7. The behavior perception-oriented convenient ultrasonic multi-channel transceiving hardware system according to claim 1, wherein an operating system of the platform with the operating system is liux, Windows or macOS, when the operating system is connected with a USB synchronous transceiving sound card, the USB synchronous transceiving sound card is powered on and enumerated to identify the USB synchronous transceiving sound card as a USB audio device, the platform with the operating system serves as a host, the USB synchronous transceiving sound card serves as a slave, and an upper computer program is designed on the platform with the operating system to control an API driven by the USB audio device to further achieve output and input of an audio data stream, so that related processing of signals is achieved on the platform with the operating system.

8. The behavior-aware-oriented convenient ultrasonic multi-channel transceiving hardware system according to claim 1, wherein the ultrasonic generating sound is provided with a 3.5mm audio signal input interface for connecting with the output of a USB synchronous transceiving sound card, the interface is internally connected with a non-inverting input end of a broadband power amplifier circuit and an input end of a voltage comparator of a signal impact protection and energy saving circuit, a relay on the signal impact protection and energy saving circuit determines a path between a linear power supply output and the broadband power amplifier circuit, and two ends of a loudspeaker are connected with a left sound channel output end of the broadband power amplifier circuit; the ultrasonic sound generation device has a frequency response range of 1K-40KHz and can send any sound wave signal in the frequency response range, the signal impact protection and energy saving circuit can prevent the loudspeaker from being damaged by large impact generated when the signal is suddenly input and disconnected, and the power amplifier circuit can be powered off and save energy when no sound source is input.

9. The convenient ultrasonic multichannel transceiving hardware system for behavioral awareness according to claim 1 or 8, wherein the speaker is an aluminum ribbon tweeter with impedance of 8 Ω and frequency response range up to 40KHz, the broadband power amplifier circuit adopts a monaural power amplifier circuit with a class a LM4766 integrated power amplifier chip as a core, and the function of adjusting five-level output power of 1/2/4/8/16W is set by switching the resistance of a feedback resistor; the linear power supply adopts a 220V alternating current input 120W and 18V double-output annular transformer with a middle tap; the signal impact protection and energy saving circuit mainly comprises an STM32F031F6P6MCU, a voltage comparator, three relays, a control key and a state indicator lamp, wherein the voltage comparator monitors an input signal in real time, namely a sound source signal decoded and output by a sound card, the voltage comparator monitors the sound source input, then external interruption is started and pulse counting is started, the three relays are started after the sound source input is monitored, and a path from a linear power supply to a broadband power amplifier circuit is opened to enable the power amplifier and the loudspeaker to be electrified and operated.

10. The behavior perception-oriented convenient ultrasonic multi-path transceiving hardware system according to claim 1 or 8, wherein a 60-degree temperature control switch and a cooling fan are adopted in the ultrasonic sound generation device, and the temperature control switch is fixed on a cooling fin of a broadband power amplification circuit, so that over-temperature and timely cooling of a power amplification chip is realized.

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