Acoustic array power supply and command downlink multiplexing system based on pulse density modulation and control method thereof
Technical Field
The invention relates to the technical field of acoustic signal processing, in particular to an acoustic array power supply and command downlink multiplexing system based on pulse density modulation and a control method thereof.
Background
The open space acoustic sensor array is formed by arranging a group of acoustic sensors in space according to a certain mode, so that acoustic information rich in space can be obtained, and the functions of noise suppression, reverberation removal, human voice interference suppression, sound source direction finding, sound source tracking, array gain and the like are realized by combining a signal processing algorithm, so that the processing quality of voice signals is improved, and the voice recognition rate in a real environment is improved. Aiming at an array topological structure, the method mainly comprises a linear array, an area array and a three-dimensional array. The acoustic sensor array is a development front in the field of array signal processing, and is widely applied to the fields of underwater sound engineering, environmental noise monitoring, voice interaction, video conference, intelligent home, unmanned aerial vehicle rescue embedded with the microphone array and the like. For different working scenes, the application range of the acoustic array is limited by configuring the acoustic sensor to fix the working parameters so as to adapt to the working environment, so that the dynamic adjustment of the working parameters of a plurality of remote acoustic array nodes is an important subject and difficult problem to be solved.
Disclosure of Invention
The invention aims to solve the problem of dynamic adjustment of working parameters of a plurality of remote acoustic array nodes in the prior art, and provides an acoustic array power supply and command downlink multiplexing system based on pulse density modulation. The main application scene is places such as school classrooms, hospitals and public places where a large amount of acoustic signals are required to be acquired. Taking a college classroom as an example, if the functions of an examination room without monitoring or remotely recording a teacher's public class and the like are to be realized, the voice signals of the teacher and the students, the acoustic signals of musical instruments of a music class or other related various signals need to be collected in the classroom in real time, and an acoustic sensor array consisting of a plurality of microphones is a sensor array applicable to the scenes.
The invention also aims to provide a control method of the acoustic array power supply and command downlink multiplexing system, so that a user of an upper computer such as a central control room can conveniently and synchronously send simple switch commands and dynamic parameter setting command signals to a plurality of acoustic sensor arrays with large areas. The signal is superimposed on the DC power line in the form of serial data and is simultaneously transmitted to all the acoustic sensor array nodes.
The technical scheme adopted for realizing the purpose of the invention is as follows:
the system comprises an upper computer control end, a power bus composed of a ground wire and a voltage wire, and a plurality of acoustic terminal nodes connected with the voltage wire, wherein:
the upper computer control end comprises an upper computer for adjusting dynamic parameters of the acoustic array and displaying waveforms of the acoustic array, a command modulation module for modulating the dynamic parameters, a high-power direct-current power supply module for supplying power to the acoustic array and an adder for superposing a power supply and command signals, wherein the upper computer is connected with the input end of the adder through the command modulation module, the high-power direct-current power supply module connected with the ground wire is connected with the input end of the adder, and the output end of the adder is connected with a voltage line of the power bus;
the acoustic terminal node comprises a command demodulation module and an acoustic array unit, wherein the command demodulation module comprises a multiplexing command signal separation module, a synchronous clock extraction module and a pulse density modulation signal demodulation module, wherein the input end of the multiplexing command signal separation module is connected with the voltage line through a branch line, one output end of the multiplexing command signal separation module is connected with the acoustic array unit through a VCC branch line to provide power, the other output end of the multiplexing command signal separation module is connected with the acoustic array unit through the pulse density modulation signal demodulation module to transmit command signals, and the input end of the synchronous clock extraction module is connected with the branch line and the output end of the synchronous clock extraction module is respectively connected with the multiplexing command signal separation module and the pulse density modulation signal demodulation module.
In the above technical scheme, the command modulation module comprises a local clock, a main control chip and a tri-state gate which are sequentially connected, wherein the main control chip comprises a reference clock in communication connection with the local clock and a pulse density modulation unit in communication connection with the tri-state gate.
In the above technical solution, the main control chip of the command modulation module is ALTERA cycle iv EP4CE15F23C8N.
In the above technical solution, the synchronous clock extraction module and the demodulation module of the pulse density modulation signal are main control chips of the command demodulation module, and the model is ALTERA cycle iv EP4CE15F23C8N.
In the above technical solution, the multiplexing command signal separation module includes a passive band-pass filter and a passive low-pass filter connected with the voltage line, the passive band-pass filter is communicatively connected with the pulse density demodulation module through an amplifier to provide a pulse density signal, and the passive low-pass filter is communicatively connected with the acoustic array to provide a power supply.
In the above technical solution, the acoustic array unit includes a crystal oscillator, a converter, a main control unit and an acoustic sensor array, where the crystal oscillator is configured to generate a local clock, the main control unit includes a bit clock phase-locked loop, a byte phase-locked loop, a bit clock distribution unit, a byte clock distribution unit and a data receiving framing, the crystal oscillator is configured to send a bit clock signal and a byte clock signal, the bit clock phase-locked loop is configured to send the bit clock signal to the bit clock distribution unit, the byte phase-locked loop is configured to send the byte signal to the byte clock distribution unit, and the bit clock distribution unit and the byte clock unit respectively distribute the received bit clock signal and byte clock signal to a plurality of output signals and send the output signals to the converter;
the converter is used for receiving and converting the bit clock signal and the byte clock signal and transmitting the bit clock signal and the byte clock signal to the acoustic sensor array, the converter is also connected with the acoustic sensor array through an analog data branch circuit so as to convert the analog signal acquired by the acoustic sensor array into a digital signal, the converted digital signal is transmitted to the data receiving framing through a digital data branch circuit, and the data receiving framing is in communication connection with the Ethernet line.
In the above technical solution, the model of the converter is ADAU7002.
In the above technical scheme, the master control unit is of the type ALTERA Cyclone IV EP4CE75F23C8N.
In another aspect of the invention, a method for controlling a pulse density modulation-based acoustic array power supply and command downlink multiplexing system comprises the steps of:
step 1, an upper computer receives acoustic data and displays acoustic array waveforms, and simultaneously, parameters to be adjusted are input through the upper computer;
step 2, the upper computer converts the corresponding parameter adjustment command into a command frame of 3 bytes, and sends the command frame to a command modulation module (the current transmission rate is 9600 bps) through a serial port, and the command modulation module modulates the command frame through pulse density;
a main control chip (ALTERA cycle IV EP4CE15F23C 8N) of the command modulation module analyzes the command frame, modulates the command frame by a carrier clock of 3.072MHz, and the modulation mode is pulse density modulation;
step 3, after the modulated signals are overlapped with the forward output end of the high-power direct-current power supply module through an adder, the signals are transmitted to all acoustic terminal nodes through a power bus;
step 4, a multiplexing command signal separation module of the acoustic terminal node separates the command signal from the power supply VCC to provide a local power supply and the command signal for the acoustic array;
and 5, the sound array executes the command and transmits the sound signal data to the upper computer through an Ethernet cable.
In the above technical solution, in step 4, when the synchronous clock extraction module detects a rising edge, the demodulation module of the pulse density adjustment signal of the acoustic terminal node is started, and the pulse density demodulation module determines whether there is command input according to the signal input period, if there is command input, the counter technology is performed, the soft threshold value is determined, and finally the command demodulation is realized. Compared with the prior art, the invention has the beneficial effects that:
1. by dynamically adjusting working parameters of a plurality of remote acoustic nodes, the working efficiency and the elastic service capability of the acoustic array are improved, and the working range of the acoustic array is expanded.
2. Through the power supply and command downlink multiplexing technology, the structure of the acoustic array is simplified, the number of transmission lines is reduced, and technical support is provided for further improving the existing acoustic array.
3. In consideration of the working environment of a plurality of acoustic array nodes, the power supply and command downlink multiplexing technology can adjust working parameters in a short time and in a large range, and time cost, labor cost and capital cost are remarkably saved.
4. The invention adopts the mode of transmitting echo signals by the network cable and downloading commands by the power line, because the network cable transmits data by adopting point-to-point UDP data packets for uploading, if the downloading commands are also downloaded by the network cable, the reliability of data uploading can be reduced. In addition, the real-time requirement of the command is high, and the network cable transmission mode cannot ensure that each acoustic array node receives and analyzes the command frame synchronously in real time.
Drawings
Fig. 1 is a block diagram of an acoustic array power supply and command downlink multiplexing device and method based on direct current carrier pulse density modulation.
Fig. 2 is a block diagram of the structure of the command modulation module.
Fig. 3 is a block diagram of the configuration of the multiplexing command separation module.
Fig. 4 is a flow chart of modulation of the acoustic array power supply and command downstream multiplexing device and method based on pulse density modulation.
Fig. 5 is a flow chart of the demodulation of the device and method for multiplexing the power supply and the command downlink of the acoustic array based on pulse density modulation.
Detailed Description
The invention is described in further detail below with reference to the drawings and the specific examples. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
Example 1
The system comprises an upper computer control end, a power bus composed of a ground wire and a voltage wire, and a plurality of acoustic terminal nodes connected with the voltage wire, wherein:
the upper computer control end comprises an upper computer for adjusting dynamic parameters of the acoustic array and displaying waveforms of the acoustic array, a command modulation module for modulating the dynamic parameters, a high-power direct-current power supply module for supplying power to the acoustic array and an adder for superposing a power supply and command signals, wherein the upper computer is connected with the input end of the adder through the command modulation module, the high-power direct-current power supply module connected with the ground wire is connected with the input end of the adder, and the output end of the adder is connected with a voltage line of the power bus;
the acoustic terminal node comprises a command demodulation module and an acoustic array unit, wherein the command demodulation module comprises a multiplexing command signal separation module, a synchronous clock extraction module and a pulse density modulation signal demodulation module, wherein the input end of the multiplexing command signal separation module is connected with the voltage line through a branch line, one output end of the multiplexing command signal separation module is connected with the acoustic array unit through a VCC branch line to provide power, the other output end of the multiplexing command signal separation module is connected with the acoustic array unit through the pulse density modulation signal demodulation module to transmit command signals, and the input end of the synchronous clock extraction module is connected with the branch line and the output end of the synchronous clock extraction module is respectively connected with the multiplexing command signal separation module and the pulse density modulation signal demodulation module.
The dynamic parameters comprise array gain, starting, stopping or dormancy and the like, the upper computer control end is in communication connection with the power bus, the power bus is connected with the acoustic terminal node after carrying out remote transmission on power signals of multiplexing commands, and the acoustic terminal node separates the multiplexing commands and is respectively connected with the acoustic array through a command branch and a power branch. The command modulation module is used for modulating the command of the acoustic sensor node (acoustic array) set by a user in the upper computer into a pulse density signal, and the pulse density demodulation module is used for demodulating the pulse density signal into a command signal of three bytes.
Example 2
The present embodiment describes the command modulation module, the multiplexed command signal separation module, and the acoustic array in further detail on the basis of embodiment 1.
Preferably, the command modulation module comprises a local clock, a main control chip and a tri-state gate which are sequentially connected, wherein the main control chip comprises a reference clock which is in communication connection with the local clock and a pulse density modulation unit which is in communication connection with the tri-state gate.
The working process is as follows: generating a continuous high-frequency rectangular carrier wave by a local clock (a clock of a command modulation module circuit board); the local clock is generated by a crystal oscillator, the frequency of the crystal oscillator is fixed, the frequency multiplication or frequency division is carried out on the basis of the local clock on the basis of a reference clock, the frequency multiplication or frequency division process is completed by a main control chip, a pulse density modulation unit modulates a quantized (0/1) command signal, the modulated command signal is supplied to a tri-state gate to complete modulation, the modulated signal is supplied to an adder, en represents an enabling end, en=1, a modulation module works, en=0, and the modulation module stops working.
Preferably, the main control chip of the command modulation module is ALTERA Cyclone IV EP4CE15F23C8N.
Preferably, the synchronous clock extraction module and the demodulation module of the pulse density modulation signal are main control chips of the command demodulation module, and the model of the main control chips is ALTERA Cyclone IV EP4CE15F23C8N.
Preferably, the multiplexing command signal separation module includes a passive bandpass filter connected to the voltage line and a passive lowpass filter communicatively connected to the pulse density demodulation module through an amplifier to provide a pulse density signal, and communicatively connected to the acoustic array to provide a power supply.
The working process is as follows: the power bus (power supply plus command signal) obtains the waveform of the command signal through a passive band-pass filter, and the command signal is fed into a pulse density modulation module through an amplifier for demodulation; meanwhile, the power bus obtains direct current voltage required by the acoustic array through the passive low-pass filter to perform power supply work.
Preferably, the acoustic array unit includes a crystal oscillator, a converter, a main control unit and an acoustic sensor array, the crystal oscillator is used for generating a local clock, the main control unit includes a bit clock phase-locked loop, a byte phase-locked loop, a bit clock distribution unit, a byte clock distribution unit and a data receiving framing, the crystal oscillator is used for sending a bit clock signal and a byte clock signal, the bit clock phase-locked loop is used for sending the bit clock signal to the bit clock distribution unit, the byte phase-locked loop is used for sending the byte signal to the byte clock distribution unit, and the bit clock distribution unit and the byte clock unit respectively distribute the received bit clock signal and the byte clock signal to a plurality of output signals and send the output signals to the converter;
the converter is used for receiving and converting the bit clock signal and the byte clock signal and transmitting the bit clock signal and the byte clock signal to the acoustic sensor array, the converter is also connected with the acoustic sensor array through an analog data branch circuit so as to convert the analog signal acquired by the acoustic sensor array into a digital signal, the converted digital signal is transmitted to the data receiving framing through a digital data branch circuit, and the data receiving framing is in communication connection with the Ethernet line.
Thus, the synchronization of the clock signals is ensured, and the high synchronization and the high reliability of sound source sampling are ensured. The data receiving framing is used for receiving the digital signals and packaging the packets into frames for uploading.
Preferably, the type of the converter is ADAU7002.
The working process is as follows: the acoustic sensor samples the space acoustic signal at the sampling frequency of 48KHz, and the sampled analog signal is framed by the converter ADAU7002 in a digital signal type through data receiving and is transmitted to the upper computer by using the gigabit Ethernet.
Preferably, the master control unit is of the type ALTERA Cyclone IV EP4CE75F23C8N.
Example 3
The control method of the acoustic array power supply and command downlink multiplexing system comprises the following steps:
after the acoustic array is built and installed and the circuit connection is completed, the acoustic signal control terminal is started to check whether the upper computer control terminal operates normally or not.
Step 1, an upper computer receives acoustic data and displays acoustic array waveforms, and simultaneously, parameters to be adjusted are input through the upper computer;
step 2, the upper computer converts the corresponding parameter adjustment command into a command frame of 3 bytes, and sends the command frame to a command modulation module (the current transmission rate is 9600 bps) through a serial port, and the command modulation module modulates the command frame through pulse density;
a main control chip (ALTERA cycle IV EP4CE15F23C 8N) of the command modulation module analyzes the command frame, modulates the command frame by a carrier clock of 3.072MHz, and the modulation mode is pulse density modulation;
step 3, after the modulated signals are overlapped with the forward output end of the high-power direct-current power supply module through an adder, the signals are transmitted to all acoustic terminal nodes through a power bus;
step 4, a multiplexing command signal separation module of the acoustic terminal node separates the command signal from the power supply VCC to provide a local power supply and the command signal for the acoustic array;
specifically, the multiplexing command signal separation module obtains a command signal waveform through a passive band-pass filter, and the command signal waveform is fed into the pulse density modulation module through an amplifier to be demodulated; meanwhile, the multiplexing command signal separation module obtains a power supply VCC required by the acoustic array through a passive low-pass filter to perform power supply work.
Meanwhile, the power bus also enters a synchronous clock extraction module, the synchronous clock extraction module guides a multiplexing command signal separation module and a pulse density demodulation module, and the pulse density demodulation module realizes the demodulation of commands;
and 5, the sound array executes the command and transmits the sound signal data to the upper computer through an Ethernet cable.
In a preferred manner, in the step 4, the synchronous clock is used for determining a starting point when extracting the command signal, and specifically, the working principle of the synchronous clock is as follows: the master unit (ALTERA cycle iv EP4CE15F23C 8N) which synchronizes the clocks uses the local high frequency crystal as the working reference clock, which is typically much higher than the carrier frequency and command signal frequency. In order to enable each acoustic sensor node to accurately capture the bit start point of the input command signal, the system designs a special synchronous clock extraction module. The module monitors the transitions of the input signal waveform in real time and identifies the starting point of each high level "1" in the modulated command signal therefrom. Since the transmission rate of the modulated command signal is fixed at 9600Hz, the period of the signal is a fixed value. According to the method, the accurate extraction of the relevant synchronous clock can be realized as long as a plurality of high-level 1's in each command byte are ensured. While command bytes may ensure that each byte contains no less than 3 high level "1" when rules are set. Thus, the method can enable accurate sampling of the downstream command bytes by each acoustic sensor node.
When the synchronous clock extraction module detects a rising edge (high level), the demodulation module of the pulse density adjusting signal of the acoustic terminal node is started, the pulse density demodulation module judges whether a command is input according to a signal input period, if the command is input, counter technology is carried out, soft threshold judgment is carried out, and finally command demodulation is realized.
Preferably, the parameter adjustment command in step 2 includes array gain, start, stop or sleep.
The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.