CN108259092A - A kind of underwater sound modem and modulator approach based on the modulation of orthogonal differential phase-shift keying (PSK) - Google Patents
A kind of underwater sound modem and modulator approach based on the modulation of orthogonal differential phase-shift keying (PSK) Download PDFInfo
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- CN108259092A CN108259092A CN201810027300.7A CN201810027300A CN108259092A CN 108259092 A CN108259092 A CN 108259092A CN 201810027300 A CN201810027300 A CN 201810027300A CN 108259092 A CN108259092 A CN 108259092A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B13/00—Transmission systems characterised by the medium used for transmission, not provided for in groups H04B3/00 - H04B11/00
- H04B13/02—Transmission systems in which the medium consists of the earth or a large mass of water thereon, e.g. earth telegraphy
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B11/00—Transmission systems employing sonic, ultrasonic or infrasonic waves
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/18—Phase-modulated carrier systems, i.e. using phase-shift keying
- H04L27/20—Modulator circuits; Transmitter circuits
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/18—Phase-modulated carrier systems, i.e. using phase-shift keying
- H04L27/22—Demodulator circuits; Receiver circuits
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Abstract
A kind of underwater sound modem and modulator approach based on the modulation of orthogonal differential phase-shift keying (PSK), the demodulator further include mode switch, emitting portion, receiving portion, USB interface and power supply module using microcontroller as core；The emitting portion is made up of the transmitting terminal signal amplification circuit, transmission energy converter and software section of hardware components program to complete the variable encoder of function, modulator and Waveform shaping device；The receiving portion is made up of reception energy converter, receiving terminal one stage signal amplifying circuit, bandwidth-limited circuit, receiving terminal second signal amplifying circuit and the software section of hardware components program to complete the demodulator and decoder of function；When the USB interface is detached from the water surface for the underwater sound modem information exchange is carried out with computer；The power supply module is used to power to the underwater sound modem, makes its normal work.The present invention has merged orthogonal differential phase-shift keying (PSK) technology, realizes the switching of transceiver and bistatic.
Description
Technical field
The present invention relates to technical field of underwater acoustic communication, especially a kind of underwater sound tune based on the modulation of orthogonal differential phase-shift keying (PSK)
Modulator-demodulator and modulator approach.
Background technology
With the development of underwater sensor technology and modern communication technology, application of the mankind to the hydrospaces environment such as ocean
Demand is continuously improved, and more and more countries start to pay attention to the research of underwater sound sensing network.Underwater sound sensing network is with sound communication
Mode carries out information exchange, to ensure data stabilization, in real time transmission, there is an urgent need for design it is a kind of small, at low cost, low in energy consumption and
The high underwater sound modem of reliability.
Retrieval is found in the prior art, and Chinese Patent Application No. 201620077806.5 is entitled：A kind of self power generation
Underwater sound modem, the invention using power generation with marine energy module carry out electric energy supplement.Above-mentioned underwater sound modem side
The design of electricity generation module is overweighted, and assumes that underwater acoustic transducer is constantly in information transmit-receive state, increases network energy consumption.In reality
In underwater environment, underwater sound modem power supply module finite energy, and be not easy to replace, how to ensure underwater sound communication quality
Under the premise of, the corresponding handover mechanism to transducer designs, to reduce network energy consumption, it appears particularly important.
Further more, Chinese Patent Application No. is 201220371949.9, it is entitled：A kind of underwater modem.The invention
Using orthogonal phase shift spread spectrum technic, modulation scheme is absolute phase shift keying, and when demodulation uses coherent demodulation scheme.By underwater
The complex environments such as ambient noise and underwater sediment(s) influence, and coherent demodulation scheme phase ambiguity easily occurs in carrier auxiliary
Phenomenon causes to demodulate misjudgment.Above-mentioned deficiency hinders effective transmission of the information under water in environment, thereby reduces data
The real-time and validity of transmission.
It is found again through retrieval, Chinese Patent Application No. 201110224601.7 is entitled：A kind of wireless and underwater sound communication
Buoy, the invention provide a kind of dependable performance, easy to operate, dimension using digital signal processing chip as signal processing core
It is high to protect intellectual management degree, the underwater sound modem carrier available for underwater sound sensing network.But the invention equipment volume weight
Amount is big, non-modular designs, complicated integral structure, power consumption are high, thereby reduces the portability of underwater sound modem with making
With the service life, it is made easily to be died during the work time because electricity dies of exhaustion, it is difficult to meet the needs of large-scale network-estabilishing.
Therefore, different communication medium how is under water considered in weak communication environment, it is a kind of both using modular method design
Can guarantee that underwater information reliably obtains, but can realize the water surface data efficient passback low cost, low-power consumption have transceiver mode
The underwater sound modem of switching capability is particularly important.
Invention content
Present invention aims to overcome that deficiency of the prior art, provide and a kind of modulated based on orthogonal differential phase-shift keying (PSK)
Underwater sound modem and modulator approach, the underwater sound modem have transceiver and bistatic switching capability, work(
Consume low, efficient and lower-price characteristic.
Goal of the invention is realized in order to solve above-mentioned technical problem, and the present invention adopts the following technical scheme that：
A kind of underwater sound modem based on the modulation of orthogonal differential phase-shift keying (PSK), using microcontroller as core, further includes
Mode switch, emitting portion, receiving portion, USB interface and power supply module；
The emitting portion is passed through by the transmitting terminal signal amplification circuit, transmission energy converter and software section of hardware components
Program forms to complete the variable encoder of function, modulator and Waveform shaping device；During transmission data, in microcontroller
In, variable encoder calls corresponding encryption algorithm that the information collected under water is carried out message sink coding, and modulator recalls number
Signal after coding is carried out digital modulation by modulation algorithm, and then Waveform shaping device calls Waveform shaping algorithm by modulated letter
Number analog signal is converted to, and be transported to transmitting terminal signal amplification circuit；Transmitting terminal signal amplification circuit is used to receive microcontroller
Device analog signal, and complete signal amplification；Transmitting transducer is connect with transmitting terminal signal amplification circuit, completes analog signal to water
The conversion of acoustical signal；
The receiving portion is electric by the reception energy converter, receiving terminal one stage signal amplifying circuit, bandpass filtering of hardware components
Road, receiving terminal second signal amplifying circuit and software section complete the demodulator and decoder group of function by program
Into；Receive energy converter, receiving terminal one stage signal amplifying circuit, bandwidth-limited circuit and receiving terminal second signal amplifying circuit sequentially
Connection；When receiving data, underwater sound signal is converted into analog signal and inputs to receiving terminal one stage signal amplification electricity by reception energy converter
Road, receiving terminal one stage signal amplifying circuit completes signal amplification, and the signal of amplification is conveyed to bandwidth-limited circuit；Band logical is filtered
Wave circuit carries out bandpass filtering to the level-one amplified signal of reception, then inputs a signal into and amplifies electricity to receiving terminal second signal
Road；Receiving terminal second signal amplifying circuit again carries out received signal signal amplification and realizes the level conversion of signal and defeated
It is sent in microcontroller；In the microcontroller, corresponding algorithm is called to convert analog signals into digital signal, demodulator first
It recalls digital demodulation algorithm to make decisions and digital demodulation, decoder finally calls decoding algorithm to complete channel decoding；
When the USB interface is detached from the water surface for the underwater sound modem information exchange is carried out with computer；
The power supply module is used to power to the underwater sound modem, makes its normal work；
The mode switch provides bistatic and transceiver both of which, when in bistatic pattern,
It sends energy converter and receives energy converter and be independent energy converter respectively, when in transceiver pattern, send energy converter and connect
Receipts energy converter is same energy converter, that is, is known as being known as receiving energy converter when sending energy converter and receiving information when sending information,
In both modes, working mechanism's all same of mode switch；
The mode switch is made of two rectifying tubes, two power resistors and two switching tubes；First rectifying tube
Terminal circuit is penetrated with one end sending and receiving after the second rectifying tube reverse parallel connection, the other end meets the one of transmitting transducer and the first power resistor
End；First switch pipe is grounded with one end after second switch pipe reverse parallel connection, and the other end connects the other end of the first power resistor
With one end of the second power resistor, the other end connection of the second power resistor receives energy converter and receiving terminal circuit.
A kind of modulator approach of underwater sound modem based on the modulation of orthogonal differential phase-shift keying (PSK), content include
Following steps：
Step 1, mode switch can automatically perceive pattern, further according to the intrinsic threshold value of itself with send signal or
The signal that person receives energy converter acquisition is compared, and the reiving/transmitting state of the underwater sound modem is determined, so as to select information
Transmission direction；
Step 2, when the underwater sound modem be emission state when, call modulation algorithm to transmission signal adjust
System, and pass through transmitting terminal signal amplification circuit and launch；
When transmitting a signal, the coding that microcontroller is adapted to according to the corresponding code system of different request calls of user,
Character signal is converted into binary signal；Then data frame is packaged into, forms effective baseband digital signal m (t)：
(1) in formula, t is the time, and Probability p is random value, different with the difference of signal；Phase-shift keying (PSK) modulation is to utilize base
Variation with Digital Signals carrier phase carrys out a kind of modulation format of transmitting digital information；Specifically it is modulated to：
Incoming serial binary information sequence is converted by serial-parallel, is divided into the sequence a that two-way rate halvesnAnd bn, then
Two level pulse signal I (t) of bipolarity and Q (t) are occurred by level conversion g (t), mapping ruler is " 1 " → "+1 ", " 0 " → "-
1”.Then to cos ωcT and sin ωcT is modulated, and obtains quadrature phase shift keying signal；After completing quadrature phase shift keying modulation
Two paths of signals is added, differential phase keying (DPSK) modulation is carried out, i.e., represents digital information with the phase difference of front and rear symbol, modulate
Last information s (t)；
In modulated process, I (t), the pulse-shaping mode of Q (t) branches are the same, wherein, the signals of I (t) branches can be with
It is expressed as：
(2) in formula,G (t) is signal envelope waveform, is rectangular wave,
Amplitude is 1；TSFor time width；ωcFor carrier angular frequencies；anThe information exactly modulated, value are "+1 " or " -1 "；g(t)
It is one section of analog signal, it and anWith cos ωcT is multiplied, and just completes modulation；In the waveform for designing g (t), communication system
Entire response be designed to only there is response to current symbol in each sampling instant of receiving terminal, and to the response of other symbols
Zero is all, modulation waveform of the signal phase in overturning when a g (t) designs squaring is avoided and discontinuous saltus step occurs
Phenomenon eliminates inter-symbol interference problem, reduces the bit error rate；
Wherein, s (t) modulated signals can be expressed as：
(3) in formula, g (t) is signal envelope waveform, for rectangular wave, amplitude 1；TSFor time width；ωcFor carrier wave angular frequency
Rate；For the corresponding phase of n-th of symbol；That is modulated signal s (t) expression be in orthogonal form for：
(4) in formula,
Understand that the power spectrum main lobe of quadrature phase shift keying is narrow by (4) formula, band efficiency is higher；
Transmitting terminal signal amplification circuit is entered after signal modulation is complete；It is second signal amplifying circuit；The first order is amplified
Circuit amplifies mode using common collector, completely asks for signal voltage, avoid the distortion of signal transmission；Second level amplifying circuit,
The amplification mode of use is also common collector mode, this amplification mode output resistance is small, and being in output stage almost can be whole
Voltage-drop loading on transmitting transducer, driving transmitting transducer using ultrasonic wave signal from analog signal be converted to the underwater sound believe
It number sees off；
Step 3, when the underwater sound modem be reception state when, utilize receiving terminal one stage signal amplifying circuit, band
Bandpass filter circuit, receiving terminal second signal amplifying circuit realize amplification, filtering and the level conversion of signal and are transported to microcontroller
In device, last microcontroller calls corresponding algorithm to convert analog signals into digital signal, makes decisions demodulation digital solution
Adjust and complete channel decoding；Its particular content is：
When the underwater sound modem is when receiving signal, reception energy converter is produced using ultrasonic wave at crystal microchip both ends
Raw voltage forms faint analog electrical signal, completes conversion of the underwater sound signal to analog electrical signal, and faint simulation is believed
Number receiving terminal one stage signal amplifying circuit is sent to, signal code is amplified；In underwater acoustic channel, environment is complicated, noise
Numerous, the frequency for the analog electrical signal that energy converter is converted back differs, before microcontroller is demodulated and decoded, the water
Acoustic modem after level-one amplification letter to carrying out bandpass filtering, and to extract effective frequency signal, it is unnecessary in signal to eliminate
Burr, reduce information transmission the bit error rate；After bandpass filtering, signal passes through receiving terminal second signal amplifying circuit, completes electricity
The adjustment that pressure is stablized amplification and electric current accordingly reduces, facilitates the acquisition signal that microcontroller is intact；
The reception signal of microcontroller acquisition is quadrature phase shift keying signal element r (t)：
The carrier multiplication of r (t) and two-way orthogonal coherent exports respectively is：
WhereinCentre frequency be twice of carrier frequency, andIt is pure baseband signal；Make
High frequency section is curbed with low-pass filter, retains baseband signal；The output of low-pass filter is：
According toValue it is different, this signal voltage can be just, or it is negative, be bipolar voltage；Modulated
It is provided in journey：" 1 " → "+1 ", " 0 " → " -1 ", therefore during judgement, also positive voltage is judged to " 1 ", negative voltage is judged to " 0 "；Anticode
The function of transformation is with transmitting terminal on the contrary, the relocatable code that decision device is exported reverts to absolute code；Absolute code is as a data frame
It enters in data buffer zone and caches, decoding of tabling look-up is carried out to code-change table, completes the reception of information；
Step 4 continues data transmission if necessary, re-executes step 1 and carries out mode page；It is connect when needing USB
During port transmission, memory information is just transferred to the transmission of USB interface waiting USB interface by microcontroller, interacts with a computer information；
If it is not required, then the underwater sound modem is made to enter dormant state, data transmission wake-up device next time is waited for, this
The data transfer ends；Step 2~3 are repeated when the underwater sound is needed to transmit.
Compared with existing underwater sound modem, a kind of water based on the modulation of orthogonal differential phase-shift keying (PSK) provided by the invention
Acoustic modem and modulator approach have the advantages that：
1. the present invention can be transmitted, power consumption using two kinds of modulation /demodulation patterns of bistatic and transceiver according to information
Its transceiver mode is configured with requirements such as life times, not only reduces the generation of failure, reduces the costs such as maintenance and manufacture, also fill
The hardware efficiency of itself has been waved in distribution；
2. the present invention maps information using the method for code-change, the volume of information is quickly and easily realized
Code realizes the Robust Transmission of underwater acoustic information；
3. the present invention uses the modulation demodulation system of orthogonal differential phase-shift keying (PSK), highly reliable；It is theoretical ripe, it is easy to real
It is existing；
4. compared to traditional modem, present invention reduces the uses of hardware, have such as only used transmission in transmitting terminal
End signal amplifying circuit eliminates the filter circuit for avoiding noise jamming and designing, in addition, the present invention D/A converter module and
Analog-to-digital conversion module integrates in the microcontroller, has not only saved cost, has also greatly reduced power consumption.
The present invention has merged orthogonal differential phase-shift keying (PSK) technology using microprocessor as core, realizes transceiver with receiving
Send out the switching split.
Description of the drawings
Fig. 1 is the present invention is based on the underwater sound modem structure diagrams that orthogonal differential phase-shift keying (PSK) is modulated；
Fig. 2 is the mode switch structure diagram the present invention is based on orthogonal differential phase-shift keying (PSK) tune；
Fig. 3 is the modulation /demodulation overall flow block diagram the present invention is based on orthogonal differential PSK Modulation Technology；
Fig. 4 sheets are modulation principle block diagram of the invention based on orthogonal differential PSK Modulation Technology.
Specific embodiment
The present invention is described in further detail below in conjunction with the accompanying drawings：
A kind of underwater sound modem based on the modulation of orthogonal differential phase-shift keying (PSK) of the present invention, as shown in Figure 1, the underwater sound
Modem further includes mode switch, emitting portion, receiving portion, USB interface and power supply mould using microcontroller as core
Block；
The emitting portion is passed through by the transmitting terminal signal amplification circuit, transmission energy converter and software section of hardware components
Program forms to complete the variable encoder of function, modulator and Waveform shaping device；During transmission data, in microcontroller
In, variable encoder calls corresponding encryption algorithm that the information collected under water is carried out message sink coding, and modulator recalls specific
Digital modulation algorithm the signal after coding is subjected to digital modulation, then Waveform shaping device calls corresponding Waveform shaping algorithm
Modulated signal is converted into analog signal, and is transported to transmitting terminal signal amplification circuit；Transmitting terminal signal amplification circuit is used
In reception microcontroller analog signal, and complete signal amplification；Transmitting transducer is connect with transmitting terminal signal amplification circuit, is completed
Analog signal is to the conversion of underwater sound signal；
The receiving portion is electric by the reception energy converter, receiving terminal one stage signal amplifying circuit, bandpass filtering of hardware components
Road, receiving terminal second signal amplifying circuit and software section complete the demodulator and decoder group of function by program
Into；Receive energy converter, receiving terminal one stage signal amplifying circuit, bandwidth-limited circuit and receiving terminal second signal amplifying circuit sequentially
Connection；When receiving data, underwater sound signal is converted into analog signal and inputs to receiving terminal one stage signal amplification electricity by reception energy converter
Road, receiving terminal one stage signal amplifying circuit completes signal amplification, and the signal of amplification is conveyed to bandwidth-limited circuit；Band logical is filtered
Wave circuit carries out bandpass filtering to the level-one amplified signal of reception, then inputs a signal into and amplifies electricity to receiving terminal second signal
Road；Receiving terminal second signal amplifying circuit again carries out received signal signal amplification and realizes the level conversion of signal and defeated
It is sent in microcontroller；In the microcontroller, corresponding algorithm is called to convert analog signals into digital signal, demodulator first
It recalls specific digital demodulation algorithm to make decisions and digital demodulation, decoder finally calls corresponding decoding algorithm to complete letter
Road decodes；
When the USB interface is detached from the water surface for the underwater sound modem information exchange is carried out with computer；
The power supply module is used to power to the underwater sound modem, makes its normal work；
The mode switch provides bistatic and transceiver both of which, when in bistatic pattern,
It sends energy converter and receives energy converter and be independent energy converter respectively, when in transceiver pattern, send energy converter and connect
Receipts energy converter is same energy converter, that is, is known as being known as receiving energy converter when sending energy converter and receiving information when sending information,
In both modes, working mechanism's all same of mode switch；
The mode switch, as shown in Fig. 2, it is by two rectifying tubes, two power resistors and two switching tube groups
Into；Terminal circuit is penetrated in one end sending and receiving after 2 reverse parallel connection of first rectifying tube 1 and the second rectifying tube, the other end connect transmitting transducer and
One end of first power resistor 3；One end after first switch pipe 5 and 6 reverse parallel connection of second switch pipe is grounded, other end connection the
One end of the other end of one power resistor 3 and the second power resistor 4, the other end connection of the second power resistor 4 receive energy converter
And receiving terminal circuit.
The work flow diagram of the present invention is illustrated in figure 3, underwater sound modem of the present invention is placed in water, water can be carried out
Lower sound communication, modulator approach include the following steps：
Step 1, mode switch can automatically perceive pattern, further according to the intrinsic threshold value of itself with send signal or
The signal that person receives energy converter acquisition is compared, and the reiving/transmitting state of the underwater sound modem is determined, so as to select information
Transmission direction；
The selection information transfer directions, detailed process are as follows：
When transmitting terminal emits signal, i.e. sending mode, signal flows through transmitting terminal signal after amplifying circuit, and what is encountered is
The rectifying tube of two reverse parallel connections, since signal voltage is much larger than the forward conduction voltage of the first rectifying tube, signal can not lose
The first rectifying tube of mode switch very is passed through, signal drives transmitting transducer that will believe under the lifting of the first power resistor
Breath is sent in underwater acoustic channel；Due to the isolation of the first power resistor, it is the voltage being amplified to flow through transmitting transducer signal
Signal, so, when it by the first power resistor reach first switch pipe after be connected immediately, signal voltage is caused to be directly grounded
It cannot flow into and receive energy converter and receiving terminal circuit, transmitting transducing can not only be driven by flowing through transmitting transducer signal voltage signal
Device, effective protection receiving terminal circuit, and itself interference of energy converter is avoided, reduce the error code of underwater sound modem
Rate；When receiving energy converter reception signal, because of the isolation of the second power resistor, the electric current of generation is small, switching tube and rectifying tube
It cannot all be connected, so transmitting transducer cannot be driven, but can be very good to be demodulated into receiving terminal circuit.
Step 2, when the underwater sound modem be emission state when, call modulation algorithm to transmission signal adjust
System, and pass through transmitting terminal signal amplification circuit and launch；
During transmission data, microcontroller calls corresponding algorithm that the information collected under water is carried out message sink coding and number tune
System, then converts digital signals into analog signal output microcontroller；And the hardware of emitting portion is amplified by transmission end signal
Circuit and transmitting transducer composition, transmitting terminal signal amplification circuit are used to receive the analog signal of microcontroller output, complete letter
Number amplification, transmitting transducer connect with transmitting terminal signal amplification circuit, completes conversion of the analog signal to underwater sound signal；
In close relations with used modulation demodulation system due to the quality of communication system, modulation makes signal special with channel
Property match, therefore, according to the characteristic of channel of underwater sound sensing network, using the modulation of orthogonal differential phase-shift keying (PSK) as of the invention
Modulation and demodulation method.
When transmitting a signal, the volume that microcontroller can be adapted to according to the corresponding code system of different request calls of user
Character signal, is converted into binary signal by code；Then data frame is packaged into, forms effective baseband digital signal m (t)：
In formula, t is the time, and Probability p is random value, different with the difference of signal；The phase-shift keying (PSK) of the present invention is modulated
Using the variation of baseband digital signal control carrier phase come a kind of modulation format of transmitting digital information；Specifically it is modulated to：
The modulation principle block diagram of the present invention is illustrated in figure 4, incoming serial binary information sequence turns by serial-parallel
It changes, is divided into the sequence a that two-way rate halvesnAnd bn, then by level conversion g (t) occur two level pulse signal I (t) of bipolarity and
Q (t), mapping ruler be " 1 " → "+1 ", " 0 " → " -1 ".Then to cos ωcT and sin ωcT is modulated, and obtains orthogonal phase shift
Keying signal；Two paths of signals is added after completing quadrature phase shift keying modulation, carries out the differential phase keying (DPSK) modulation of next step, i.e.,
Digital information is represented with the phase difference of front and rear symbol, modulates last information s (t)；
In modulated process, I (t), the pulse-shaping mode of Q (t) branches are the same, wherein, the signals of I (t) branches can be with
It is expressed as
Wherein,G (t) is signal envelope waveform, for rectangular wave, width
Spend is 1；TSFor time width；ωcFor carrier angular frequencies；anThe information exactly modulated, value are "+1 " or " -1 "；G (t) is
One section of analog signal, it and anWith cos ωcT is multiplied, and just completes modulation；In the waveform for designing g (t), the present invention is communication
The entire response of system is designed to only there is response to current symbol in each sampling instant of receiving terminal, and to other symbols
Response is all zero, and it is discontinuous to avoid modulation waveform appearance of the signal phase in overturning when a g (t) designs squaring
Hopping phenomenon eliminates inter-symbol interference problem, reduces the bit error rate；
S (t) modulated signals can be expressed as
In formula,For the corresponding phase of n-th of symbol.Modulated signal s (t) expression be in orthogonal form for
In formula,
Transmitting terminal signal amplification circuit is entered after signal modulation is complete；It is second signal amplifying circuit；The first order is amplified
Circuit amplifies mode using common collector, completely asks for signal voltage, avoid the distortion of signal transmission；Second level amplifying circuit,
The amplification mode of use is also common collector mode, this amplification mode output resistance is small, and being in output stage almost can be whole
Voltage-drop loading on transmitting transducer, driving transmitting transducer using ultrasonic wave signal from analog signal be converted to the underwater sound believe
It number sees off.
Step 3, when the underwater sound modem be reception state when, utilize receiving terminal one stage signal amplifying circuit, band
Bandpass filter circuit, receiving terminal second signal amplifying circuit and demodulating algorithm complete the reception and processing of signal；Its particular content is：
When receiving data, because the hardware of receiving portion is by reception energy converter, receiving terminal one stage signal amplifying circuit, band
Bandpass filter circuit and receiving terminal second signal amplifying circuit composition receive energy converter and underwater sound signal are converted into receiving terminal level-one letter
Analog signal in number amplifying circuit, receiving terminal one stage signal amplifying circuit complete the amplification of analog signal, later bandpass filtering
The bandpass filtering of circuit realization receiving terminal one stage signal amplifying circuit amplified signal, and receiving terminal second signal amplifying circuit and band
Bandpass filter circuit connects, and realizes the level conversion of signal and is transported in microcontroller, and last microcontroller calls corresponding calculate
Method converts analog signals into digital signal, makes decisions demodulation digital demodulation and completes channel decoding；
When the underwater sound modem is when receiving signal, reception energy converter is produced using ultrasonic wave at crystal microchip both ends
Raw voltage forms faint analog electrical signal, completes conversion of the underwater sound signal to analog electrical signal, and faint simulation is believed
Number receiving terminal one stage signal amplifying circuit is sent to, signal code is amplified；In underwater acoustic channel, environment is complicated, noise
Numerous, the frequency for the analog electrical signal that energy converter is converted back differs, before microcontroller is demodulated and decoded, the present invention
To carrying out bandpass filtering after level-one amplification letter, to extract effective frequency signal, unnecessary burr in signal is eliminated, reduces letter
Cease the bit error rate of transmission；After bandpass filtering, signal pass through receiving terminal second signal amplifying circuit, complete voltage stablized amplification and
The adjustment that electric current accordingly reduces facilitates the acquisition signal that microcontroller is intact；
The demodulating algorithm, corresponding with the modulation of orthogonal differential phase-shift keying (PSK), demodulation scheme of the invention uses coherent demodulation
Add anticode converter technique；The step of coherent demodulation is：The orthogonal baseband signal of two-way is isolated with the orthogonal coherent carrier of two-way,
The symbol of I (t), Q (t) two-way is just obtained after the judgement of two-way baseband signal, by anticode transformation and parallel-serial conversion, as serial number
According to output；Coherent demodulation is implemented as：
Signal is received first after bandpass filtering, and the quadrature phase shift keying signal element r (t) for being input to demodulator is：
The carrier multiplication of r (t) and two-way orthogonal coherent exports respectively is：
Each branch has two, whereinCentre frequency be twice of carrier frequency, andIt is
Pure baseband signal, that is, the part needed；Then, high frequency section is curbed using low-pass filter, and protected
Baseband signal is stayed to prepare for subsequent processing；
The output of low-pass filter is
According toValue it is different, this signal voltage can be just, or negative, therefore be bipolar voltage.It is modulating
It once provides in the process：" 1 " → "+1 ", " 0 " → " -1 ", therefore during judgement, also positive voltage is judged to " 1 ", negative voltage is judged to " 0 ".
The function of anticode transformation is with transmitting terminal on the contrary, the relocatable code that decision device is exported reverts to absolute code；
Absolute code enters in data buffer zone cache as a data frame；Decoder again looks into code-change table
Table restores the ASCII character of character, further restores character, restores script information；
Step 4, after having demodulated data, when do not need to transmission data when, the underwater sound modem stores information
Come and in a dormant state, the next step of host is waited for wake up；When if desired sending information, the underwater sound modem can be into
Row sending mode selects；The present invention provides two kinds of sending mode selections：The underwater sound transmits and USB interface transmission；It is passed when needing the underwater sound
Step 1~3 are repeated when defeated；When USB interface is needed to transmit, memory information is just transferred to USB interface and waits for USB by microcontroller
The transmission of interface carries out the information exchange with computer.
Basic principle, the main features and advantages of the present invention have been shown and described above.The technical staff of the industry should
Understand, the present invention is not limited to the above embodiments, and the above embodiments and description only describe the originals of the present invention
Reason, without departing from the spirit and scope of the present invention, various changes and improvements may be made to the invention, these changes and improvements
It all fall within the protetion scope of the claimed invention.The claimed scope of the invention is by appended claims and its equivalent circle
It is fixed.
Claims (2)
1. underwater sound modem using microcontroller as core, further includes mode switch, emitting portion, receiving portion, USB and connects
Mouth and power supply module；
The emitting portion passes through program by the transmitting terminal signal amplification circuit, transmission energy converter and software section of hardware components
To complete the variable encoder of function, modulator and Waveform shaping device composition；It, in the microcontroller, can during transmission data
Becoming encoder calls corresponding encryption algorithm that the information collected under water is carried out message sink coding, and modulator recalls digital modulation calculation
Signal after coding is carried out digital modulation by method, and then Waveform shaping device calls Waveform shaping algorithm to convert modulated signal
For analog signal, and it is transported to transmitting terminal signal amplification circuit；Transmitting terminal signal amplification circuit is simulated for receiving microcontroller
Signal, and complete signal amplification；Transmitting transducer is connect with transmitting terminal signal amplification circuit, completes analog signal to underwater sound signal
Conversion；
The receiving portion by hardware components reception energy converter, receiving terminal one stage signal amplifying circuit, bandwidth-limited circuit, connect
Receiving end second signal amplifying circuit and software section are made up of program to complete the demodulator and decoder of function；It connects
Energy converter, receiving terminal one stage signal amplifying circuit, bandwidth-limited circuit and receiving terminal second signal amplifying circuit is received to be sequentially connected with；
When receiving data, underwater sound signal is converted into analog signal and inputs to receiving terminal one stage signal amplifying circuit by reception energy converter, is connect
Receiving end one stage signal amplifying circuit completes signal amplification, and the signal of amplification is conveyed to bandwidth-limited circuit；Bandpass filtering electricity
Road carries out bandpass filtering to the level-one amplified signal of reception, then inputs a signal into and gives receiving terminal second signal amplifying circuit；It connects
Receiving end second signal amplifying circuit again carries out received signal signal amplification and the level conversion for realizing signal and is transported to
In microcontroller；In the microcontroller, corresponding algorithm is called to convert analog signals into digital signal first, demodulator is adjusted again
It is made decisions with digital demodulation algorithm and digital demodulation, decoder finally calls decoding algorithm to complete channel decoding；
When the USB interface is detached from the water surface for the underwater sound modem information exchange is carried out with computer；
The power supply module is used to power to the underwater sound modem, makes its normal work；
The mode switch provides bistatic and transceiver both of which, when in bistatic pattern, sends
Energy converter and reception energy converter are independent energy converter respectively, when in transceiver pattern, send energy converter and reception is changed
Energy device is same energy converter, that is, is known as referred to as receiving energy converter when sending energy converter and receiving information when sending information, at this
In both of which, working mechanism's all same of mode switch；
The mode switch is made of two rectifying tubes, two power resistors and two switching tubes；First rectifying tube and
Terminal circuit is penetrated in one end sending and receiving after two rectifying tube reverse parallel connections, and the other end connects one end of transmitting transducer and the first power resistor；
One end after first switch pipe and second switch pipe reverse parallel connection is grounded, and the other end connects the other end and the of the first power resistor
One end of two power resistors, the other end connection of the second power resistor receive energy converter and receiving terminal circuit.
2. a kind of underwater sound modem based on the modulation of orthogonal differential phase-shift keying (PSK) obtains modulation methods according to claim 1
Method, it is characterised in that：This method content includes the following steps：
Step 1, mode switch can automatically perceive pattern, further according to the intrinsic threshold value of itself with sending signal or connecing
The signal for receiving energy converter acquisition is compared, and the reiving/transmitting state of the underwater sound modem is determined, so as to which information be selected to transmit
Direction；
Step 2, when the underwater sound modem be emission state when, call modulation algorithm to transmission signal be modulated, and
Launched by transmitting terminal signal amplification circuit；
When transmitting a signal, the coding that microcontroller is adapted to according to the corresponding code system of different request calls of user, word
Symbol signal is converted into binary signal；Then data frame is packaged into, forms effective baseband digital signal m (t)：
(1) in formula, t is the time, and Probability p is random value, different with the difference of signal；Phase-shift keying (PSK) modulation is to utilize base band number
The variation of word signal control carrier phase carrys out a kind of modulation format of transmitting digital information；Specifically it is modulated to：
Incoming serial binary information sequence is converted by serial-parallel, is divided into the sequence a that two-way rate halvesnAnd bn, then by electricity
Flat turn changes g (t) and occurs two level pulse signal I (t) of bipolarity and Q (t), and mapping ruler is " 1 " → "+1 ", " 0 " → " -1 ".So
Afterwards to cos ωcT and sin ωcT is modulated, and obtains quadrature phase shift keying signal；It completes two-way after quadrature phase shift keying is modulated
Signal is added, and is carried out differential phase keying (DPSK) modulation, i.e., is represented digital information with the phase difference of front and rear symbol, modulate last
Information s (t)；
In modulated process, I (t), the pulse-shaping mode of Q (t) branches are the same, wherein, the signal of I (t) branches can represent
For：
(2) in formula,G (t) is signal envelope waveform, is rectangular wave, and amplitude is
1；TSFor time width；ωcFor carrier angular frequencies；anThe information exactly modulated, value are "+1 " or " -1 "；G (t) is one section
Analog signal, it and anWith cos ωcT is multiplied, and just completes modulation；In the waveform for designing g (t), the entire of communication system
Response is designed to only there is response to current symbol in each sampling instant of receiving terminal, and the response of other symbols is all
Zero, it avoids modulation waveform appearance discontinuous saltus step of the signal phase in overturning when a g (t) designs squaring and shows
As eliminating inter-symbol interference problem, reducing the bit error rate；
Wherein, s (t) modulated signals can be expressed as：
(3) in formula, g (t) is signal envelope waveform, for rectangular wave, amplitude 1；TSFor time width；ωcFor carrier angular frequencies；
For the corresponding phase of n-th of symbol；That is modulated signal s (t) expression be in orthogonal form for：
(4) in formula,
Understand that the power spectrum main lobe of quadrature phase shift keying is narrow by (4) formula, band efficiency is higher；
Transmitting terminal signal amplification circuit is entered after signal modulation is complete；It is second signal amplifying circuit；First order amplifying circuit,
Mode is amplified using common collector, signal voltage is completely asked for, avoids the distortion of signal transmission；Second level amplifying circuit uses
Amplification mode be also common collector mode, this amplification mode output resistance is small, and being in output stage almost can be whole electricity
On transmitting transducer, signal from analog signal is converted to underwater sound signal using ultrasonic wave and sent by driving transmitting transducer for pressure loading
It goes out；
Step 3, when the underwater sound modem be reception state when, utilize receiving terminal one stage signal amplifying circuit, band logical filter
Wave circuit, receiving terminal second signal amplifying circuit realize amplification, filtering and the level conversion of signal and are transported to microcontroller
In, last microcontroller calls corresponding algorithm to convert analog signals into digital signal, makes decisions demodulation digital demodulation
And complete channel decoding；Its particular content is：
When the underwater sound modem is when receiving signal, reception energy converter utilizes what ultrasonic wave generated at crystal microchip both ends
Voltage forms faint analog electrical signal, completes conversion of the underwater sound signal to analog electrical signal, and faint analog signal is sent
Enter to receiving terminal one stage signal amplifying circuit, signal code is amplified；In underwater acoustic channel, environment is complicated, and noise is numerous,
The frequency for the analog electrical signal that energy converter is converted back differs, before microcontroller is demodulated and decoded, the underwater sound tune
Modulator-demodulator, to extract effective frequency signal, eliminates unnecessary hair in signal to carrying out bandpass filtering after level-one amplification letter
Thorn reduces the bit error rate of information transmission；After bandpass filtering, signal passes through receiving terminal second signal amplifying circuit, completes voltage quilt
Stablize the adjustment that amplification and electric current accordingly reduce, facilitate the acquisition signal that microcontroller is intact；
The reception signal of microcontroller acquisition is quadrature phase shift keying signal element r (t)：
The carrier multiplication of r (t) and two-way orthogonal coherent exports respectively is：
WhereinCentre frequency be twice of carrier frequency, andIt is pure baseband signal；
High frequency section is curbed using low-pass filter, retains baseband signal；The output of low-pass filter is：
According toValue it is different, this signal voltage can be just, or it is negative, be bipolar voltage；In modulated process
Regulation：" 1 " → "+1 ", " 0 " → " -1 ", therefore during judgement, also positive voltage is judged to " 1 ", negative voltage is judged to " 0 "；Anticode converts
Function and transmitting terminal on the contrary, the relocatable code that decision device is exported reverts to absolute code；Absolute code enters as a data frame
It is cached into data buffer zone, decoding of tabling look-up is carried out to code-change table, completes the reception of information；
Step 4 continues data transmission if necessary, re-executes step 1 and carries out mode page；It is passed when needing USB interface
When defeated, memory information is just transferred to the transmission of USB interface waiting USB interface by microcontroller, interacts with a computer information；If
It does not need to, then the underwater sound modem is made to enter dormant state, wait for data transmission wake-up device next time, this data
The end of transmission；Step 2~3 are repeated when the underwater sound is needed to transmit.
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| CN110007295A (en) * | 2019-04-30 | 2019-07-12 | 中国船舶工业***工程研究院 | The signal acquisition protector of energy converter is set in a kind of underwater sound transmitting-receiving conjunction |
| CN111190365A (en) * | 2019-12-31 | 2020-05-22 | 中国海洋石油集团有限公司 | Two-stage wake-up circuit for underwater acoustic communication and wake-up method thereof |
| CN111277525A (en) * | 2020-01-22 | 2020-06-12 | 北京工业大学 | Underwater acoustic communication modulation and demodulation module of frequency combination signal |
| CN112003650A (en) * | 2020-08-31 | 2020-11-27 | 西北工业大学 | Underwater acoustic communication receiving device and communication method based on intelligent mobile terminal |
| CN115001598A (en) * | 2022-04-29 | 2022-09-02 | 厦门大学 | Remote-controlled underwater acoustic signal transmitting device |
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| CN110007295A (en) * | 2019-04-30 | 2019-07-12 | 中国船舶工业***工程研究院 | The signal acquisition protector of energy converter is set in a kind of underwater sound transmitting-receiving conjunction |
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