CN103763002B - A kind of multipoint communication system based on PZT in solid structure and method - Google Patents
A kind of multipoint communication system based on PZT in solid structure and method Download PDFInfo
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Abstract
The invention discloses a kind of multipoint communication system based on PZT in solid structure and method, this system includes: sensor, intelligent sensing circuit, acoustic-electrical transducer, signal processing system.Described method includes: by solid structure medium emission detectable signal；Receive detectable signal, and the detectable signal received is carried out time reversal process and spread processing；Signal after time reversal is carried out carrier modulation, and the signal after modulation carries binary signal information；Encourage, by binary signal, the PZT sheet that described sensor is corresponding, make PZT sheet produce stress wave, and stress wave is transferred to receiving terminal；The signal received is carried out carrier wave demodulation by receiving terminal, and pseudo-spread spectrum code corresponding with described sensor for the signal after demodulation is carried out coherently despreading process, it is thus achieved that sensor signal.The present invention preferably solves frequency dispersion, multipath and the multi-modal problem existed during stress wave propagation in solid dielectric, makes up dispersion thus reaches synchronization signal detection.Use spread spectrum to realize the non-interfering independent communication of multichannel, the ability of antinoise and anti-interference in solid dielectric multi-point, can be greatly improved.
Description
Technical field
The present invention relates to signal detection and field of wireless communications, particularly relate to a kind of towards solid dielectric based on
PZT realizes the system and method for multi-point.
Background technology
Existing solid structure infrastructure the most aging, their sustainability is monitored be current
One of big challenge, especially pipeline configuration, valve class formation and twisted wire structure etc., do not have the direct method can
With.Because the frequent generation of fault, they are carried out continuous detecting assessment and arranges corresponding maintenance activity
It is the most necessary.Elongated solid structure is monitored continuously and needs to dispose multiple sensor, a sensor
In network, data communication is likely to occur between two or more sensor node, it is also possible to occur in sensing
Between device node and a central processing unit, so in the urgent need to realizing non-interfering multipoint data communication
Technology.
In classical communication theory, carry after the signal of information is modulated and sent by transmitting terminal excitation, letter
Number propagated by physical medium, such as empty gas and water or cable, then received by a receiving terminal,
The signal received is demodulated, it is possible to recover the information propagated.Such as, at wireless communication system
Middle electromagnetic signal carries out data transmission often as carrier.Transmission medium is air.In underwater sound communication, profit
Transmitting information with acoustic signal, transmission medium is water.Transmission medium is air.At underwater sound communication, utilize
Acoustic signal transmission information, transmission medium is water.Existing structural health detection sensor network uses also
Improve traditional scheme, as radio communication and acoustic communication carry out data communication.But when applying to sealing
Time in environmental unit, such as the pipeline being buried under the ground, the sub sea upper mounting plate of hollow-core construction and valve type etc.
Frame for movement, electromagnetic communication is to be difficult to, because electromagnetic wave signal propagates meeting sternly in soil or water
Heavily decay, there is also the phenomenon of electromagnetic shielding, so causing propagation distance the shortest.Due to elastic stress
The availability of ripple wideband frequency, do not have electromagnetic shielding phenomenon, easily identify and be prone to the advantages such as measurement,
On solid dielectric, carry out heat transfer agent communication currently with PZT generation elastic wave and there is wide application
Background.
Chinese patent 102954893A discloses a kind of nanoparticle inks base for monitoring structural health conditions
The method and system of piezoelectric transducer distributed network.This system includes the knot to be monitored for structural health
Structure, also includes piezoelectric transducer assembly distributed of deposited nanoparticle inks base on this structure
Network, each assembly all includes the piezoelectric transducer of multiple nanoparticle inks base and multiple for interconnecting
Multiple conductive ink power of sensor and communication wire assembly.The method also includes using data communication network
Network via come from nanoparticle inks base piezoelectric transducer assembly one or more signals retrieval and
Process the structural health data of structure.This patent relate to the multi-point of piezoelectric transducer, but does not has
Multi-point is realized based on CDMA technology.
Chinese patent 102062747A the invention discloses a kind of based on piezoelectric ceramics and wavelet packet analysis
Concrete filled steel tubular member steel pipe walls peels off monitoring method, belongs to concrete filled steel tubular member steel pipe walls and peels off situation
Monitoring field.Method particularly includes: on outer wall of steel pipe, paste multiple piezoceramic transducer, at steel pipe
Inside concrete embedment intelligent aggregate, by high-frequency signal injection intelligent aggregate, high-frequency signal collection be
System gathers the output signal of sensor in steel pipe walls and this signal data is reached Computerized analysis system;So
After carry out wavelet packet analysis, draw the energy indexes of defined each sensor: and choose institute's monitoring surface
The energy indexes being not likely to produce stripping damage position represents the energy level without peeling off injury region;Finally define
One damage criterion, is estimated the bond state of each sensor position of steel pipe walls.This patent
It is not directed to CDMA technology and realizes multi-point, the most do not use time reversal to solve the problems such as frequency dispersion.
Above-mentioned patent has related to piezoelectric transducer communication issue, stress wave in the most unresolved solid dielectric
Frequency dispersion, multipath and multi-modal problem during propagation.But, sense in the solid structure of multisensor
The increase of the quantity of device node is frequent with potential data cube computation, and modern Application program typically requires more multiple
Miscellaneous communication architecture, i.e. realizes multisensor communication in identical transmission medium simultaneously.In order to keep away
Exempt from the interference of signal, in the urgent need to the new side in same medium, different channel signals can distinguished mutually
Method.
Summary of the invention
For solving above-mentioned technical problem, it is an object of the invention to provide one based on PZT at solid structure
In multipoint communication system and method, preferably solve stress wave in solid dielectric by this system and method
Frequency dispersion, multipath and the multi-modal problem existed during propagation, thus reach multi channel signals independent communication.
Improve the versatility of signal intensity and communication system, using the teaching of the invention it is possible to provide multiple business service, have higher
Frequency efficiency and antinoise, the anti-interference and ability of anti-multipath fading.
The purpose of the present invention is realized by following technical scheme:
A kind of multipoint communication system based on PZT in solid structure, including:
Sensor, intelligent sensing circuit, acoustic-electrical transducer, signal processing system；Described
Sensor, for producing different data types, including numeral, text and video type；
Intelligent sensing circuit, for embedding the data signal of corresponding sensor；
Acoustic-electrical transducer, produces elastic stress wave, for transmitting described different data type；
For gathering the data signal of described sensor, and the data of collection are carried out time reversal process,
Data signal after processing time reversal carries out carrier modulation, and the signal after described modulation carries binary system
Signal message, finally obtains respective sensor data at receiving terminal.
One realizes multicast routing method based on PZT in solid structure, including:
Using solid structure as medium emission detectable signal；
Receive detectable signal, and the detectable signal received is carried out time reversal process and spread processing.
Described spread processing is: the data of sensor encode in solid structure becomes binary signal, by difference
The frequency spectrum of pseudo-extended code broadening difference sensing sources data signal.
Signal after time reversal is carried out carrier modulation, and the signal after modulation carries binary signal information；
Encourage, by binary signal, the PZT sheet that described sensor is corresponding, make PZT sheet produce stress wave,
And stress wave is transferred to receiving terminal；
The signal received is carried out carrier wave demodulation by receiving terminal, and by the signal after demodulation and described sensor
Corresponding pseudo-spread spectrum code carries out coherently despreading process, it is thus achieved that sensor signal.
Compared with prior art, one or more embodiments of the invention can have the advantage that
The present invention is the method and system in solid structure by multichannel PZT real-time data communication, i.e. solid
Body structure realizes the independent communication of multiple sensor PZT data based on CDMA technology.Creative
The signal that ground receives after proposing to detect channel carries out time reversal process, again by launching after being modulated
End sends, and utilizes the time-reversal focusing characteristic of sound wave, can improve signal intensity, preferably solve
Frequency dispersion, multipath and the multi-modal problem existed during stress wave propagation in solid dielectric.Use spread spectrum
Realize the non-interfering independent communication of multichannel, antinoise can be greatly improved in solid dielectric multi-point
Ability with anti-interference.System and method described above can be applied in different elongated solid structures,
Such as pipeline configuration, valve type structure, bar structure, plate structure and twisted wire structure etc..
Accompanying drawing explanation
Fig. 1 is the multiple sensor integrated system of (such as pipeline etc.) in solid structure based on PZT
Structural representation；
Fig. 2 is to realize multicast routing method flow chart in solid structure based on PZT；
Fig. 3 is to realize multiple sensor PZT data communication based on CDMA technology in solid structure
Block diagram；
Fig. 4 is OQPSK modulation and the OQPSK of multiple sensor PZT data communication in solid structure
Coherent demodulation block diagram；
Fig. 5 is spread spectrum and the despreading technology frame chart of multiple sensor PZT data communication in solid structure.
Detailed description of the invention
For making the object, technical solutions and advantages of the present invention clearer, below in conjunction with embodiment and accompanying drawing pair
The present invention is described in further detail.
Solid structure mentioned in the present invention is a kind of medium that can propagate stress wave.Described system bag
Include: sensor, intelligent sensing circuit, acoustic-electrical transducer, signal processing system；Described sensor, uses
In producing different data types, including numeral, text and video type；Intelligent sensing circuit, is used for
Embed the data signal of corresponding sensor；Acoustic-electrical transducer, produces elastic stress wave, is used for transmitting institute
State different data types；For gathering the data signal of described sensor, and the data of collection are carried out
Time reversal processes, and the data signal after processing time reversal carries out carrier modulation, after described modulation
Signal carries binary signal information, finally obtains respective sensor data at receiving terminal.As it is shown in figure 1,
Sensor 102 is arranged on sensor in solid structure 101, and sensor can be temperature sensor, strain
The identical or different types such as sensor, velocity sensor, acceleration transducer, imageing sensor, so
Different data types can be produced, including numeral, text and video type.Intelligent sensing circuit 103,
Each sensor has signal corresponding thereto to process flush type circuit；Piezoelectric ceramic piece 104 and piezoelectricity pottery
Ceramics 105 both can also be as shockwave sensor as executor；Receiving device 106 can be from
Piezoelectric ceramic piece 105 receives analogue signal, and the analogue signal received is converted into digital signal.
Computer server and advanced signal processing system can process digital signal thus obtain each sensor
Entrained data message.
Above-mentioned multi-address communication system realizes multi-channel data same in solid structure based on CDMA technology
Step communication.And can not interfere with each other to another independent communication put concrete from a sensing point.Can apply to
In dissimilar solid structure, as pipeline configuration, valve type structure, bar structure, plate structure and twisted wire are tied
Structure etc..
Above-mentioned PZT can mutually can change as executor and sensor, executor and sensor.
The elastic stress wave produced by acoustic-electrical transducer can transmit different data types, including numeric type,
Text-type and video type etc..
The signal processing system of above-mentioned advanced person includes carrying out the corresponding signal of each sensor at time reversal
Reason and spread processing are the frequency dispersion existed when it can preferably solve stress wave propagation in solid dielectric, many
Path and multi-modal problem.And above-mentioned advanced signal-processing system uses Direct Sequence Spread Spectrum Communication technology
Model, spread spectrum substantially increases the ability of antinoise and anti-interference, does not does realizing multichannel
The independent communication disturbed.It is real that advanced signal-processing system uses offset quadraphase shift keying system (OQPSK)
Existing multi-sensor information modulation.Because there being many resonant frequencies, changing carrier modulation frequency and can reach one
Individual good demodulation effect.Described spread spectrum uses orthogonal geocoding and quasi-orthogonal intersection to come district
Dividing the data channel of different sensors, the spread spectrum code of employing is m code, Gold code and M code.Described
Orthogonal geocoding solid dielectric communicate in, application different rank Walsh code can meet difference
The different transmission rates of channel.
The present embodiment additionally provides one and realizes multi-point in solid structure based on PZT as shown in Figure 2
Method, the method realizes multiple sensor PZT data communication based on CDMA technology；Described method bag
Include:
Step 10 passes through solid structure medium emission detectable signal；
Step 20 receives detectable signal, and the detectable signal received is carried out time reversal process and expansion
Frequency processes.Described spread processing is: the data of sensor encode in solid structure becomes binary signal,
Frequency spectrum by different pseudo-extended code broadening difference sensing sources data signals.
Step 30 carries out carrier modulation to the signal after time reversal, and the signal after modulation carries binary system
Signal message；
Step 40 encourages, by binary signal, the PZT sheet that described sensor is corresponding, makes PZT sheet produce
Stress wave, and stress wave is transferred to receiving terminal；
The signal received is carried out carrier wave demodulation by step 50 receiving terminal, and by the signal after demodulation and institute
The pseudo-spread spectrum code stating sensor corresponding carries out coherently despreading process, it is thus achieved that sensor signal.
If Fig. 3 is to realize multiple sensor PZT data communication based on CDMA technology in solid structure
Block diagram, frequency dispersion, multipath and the multi-modal problem existed during stress wave propagation in solid dielectric, so this
The signal that invention receives after proposing to detect channel carries out time reversal process, again by sending out after being modulated
Penetrate end to send, utilize the time-reversal focusing of ripple, signal intensity can be improved, overcome owing to elastic wave passes
Broadcast serious channel frequency dispersion, multipath and the multi-modal problem caused.
First a detectable signal 201 is launched by the piezoelectric patches 202 of transmitting terminal, by long shape solid structure
Medium sends 206.After channel response, the piezoelectric patches 203 at receiving terminal is due to inverse piezoelectric effect
Signal 204 after channel detection can be received.The signal received is carried out time reversal again and processes 205.
In solid structure, the data 207 of all the sensors are all coded as binary signal 208, then
With the frequency spectrum 209 of the different pseudo-extended code broadening difference sensing sources data signal that spectrum-spreading code generator produces.
Wherein need in advance according to number of probes in solid structure, determine spread spectrum code type.Assume sensor
Number is n, then the number of spread spectrum code is also n, and is one-to-one relationship, say, that a sensing
The corresponding spread spectrum code of device data.Then the signal after time reversal is carried out carrier modulation 210 again, adjusts
Signal after system carries binary signal information 208, encourages the PZT that each sensor is corresponding after amplification
Sheet 202 [in equivalent Fig. 1 104], PZT sheet produces stress wave under signal encourages, and solid by long shape
Body structured media sends (206), and stress wave generally individually exists noise and outside during medium transmission
The factors 211 such as interference.When stress wave reaches receiving terminal, stress wave can make PZT sheet 203 [etc. of receiving terminal
With 105 in Fig. 1] produce vibration, due to inverse piezoelectric effect, the corresponding signal of telecommunication will be produced.Each PZT
The signal received is carried out carrier wave demodulation 212 by sheet, and by corresponding with each sensor for signal after demodulation
Pseudo-spread spectrum code carries out coherently despreading and processes 213.Here, need the pseudo-code between ensureing spread spectrum and despreading
Synchronize 214 and ensure the relatively low bit error rate.Demodulated despread after, original base band two can be recovered and enter
Signal 215 processed, thus obtain sensor signal 216.
As shown in Figure 4, for multisensor PZT data communication system OQPSK (Offset Quadrature
Phase Shift Keying) method figure, OQPSK modulate (204) and OQPSK coherent demodulation (210) two
Major part composition.The method that the present invention relates to process multisensor real-time PZT data communication.If
The detection scope of data of each sensor is little, as temperature sensor measurement data just can with 4 or
8 binary code representations, then modulator approach uses BPSK (Binary Phase Shift Keying) method.
But the measurement scope of each sensor or a portion sensor is relatively big (such as pressure etc.), then measure
After data change into binary sequence, figure place is the most long, then need to use OQPSK method.Due to OQPSK
Be the four kinds of outs of phase utilizing carrier wave to characterize digital information, each carrier phase represents two bits
Information, therefore for input sensing data sequence of binary digits should first be grouped.Will be every
It is one group that two bits are compiled, respectively 00, and 01,10,11 four kind of combination, the most respectively by four kinds of differences
Carrier phase characterize.
The manipulator of OQPSK can be regarded as being made up of two BPSK manipulators, the serial two of input
Binary information sequence is divided into, through serial parallel conversion 2041, the sequence that two-way speed halves, and one is referred to as in the same direction
Branch road, i.e. I branch road；One claims quadrature branch, i.e. Q branch road.(Q props up first to descend tributary signal in the drawings
Road) skewT/22042, wherein T is code-element period, due to the skew of two branch road code element half periods, every time
Only one road, it may happen that polarity upset, will not occur the phenomenon that two branch road code element polarity overturn simultaneously.Cause
This, OQPSK signal phase can only saltus step 0 °, ± 90 °, do not have the phase hit of 180 °, so
OQPSK overcomes the phase hit of l80 ° of QPSK.
Level generator produces ambipolar two level signals U respectively according to binary sequencet2043 Hes
Vt2044, wherein UtFor in-phase component, VtFor quadrature component.Then produced by carrier generator 2045
Raw Coswt (referred to as homophase carrier wave), is on the one hand directly modulated in-phase branch signal；On the other hand
Carrier wave is processed 2046 through phase shift pi/2, obtains after Sinwt (referred to as quadrature carrier) orthogonal tributary signal
It is modulated, and i.e. can get OQPSK letter after the signal addition after in-phase branch and quadrature branch modulation
Numbers 2047.
OQPSK demodulator uses two orthogonal carrier signals to realize coherent demodulation.Pass through carrier auxiliary
Circuit 2101, produces coherent carrier 2102, respectively homophase carrier wave and quadrature carrier is supplied to in-phase branch
With the correlator of quadrature branch, through Integral Processing 2103 and 2104, pass through bit timing recovery 2105 simultaneously
Ensure the synchronization of signal.Then two-way is each implemented to adjudicate 2106 and 2107, and in-phase branch will obtain
Decision signal carries out T/2 skew 2108, last and quadrature branch decision signal parallel serial conversion 2109, thus
Recover the original sensor binary data information needing transmission.
Fig. 5 is spread spectrum and the despreading technology frame chart of multiple sensor PZT data communication in solid structure.Main
To be conciliate spread spectrum module 210 by spread spectrum module 203 to form, the present invention will spread theoretical introducing multi-data source
In stress wave multichannel communication, utilize sequence orthogonality and quasi-orthogonality to distinguish different sensors data source.
With frequency, simultaneously under conditions of, each receives piezoelectric patches and goes out according to the differential separation between unlike signal code
The signal needed.Different sensors specifically can include the different types of data such as numerical value, text and video,
This patent uses different pseudo-random sequences to distinguish different data types as spread spectrum code.Although puppet with
Machine sequence has good autocorrelation performance, but its cross correlation is less desirable, because cross correlation value
It not to be zero everywhere.If pseudo-random sequence is used simultaneously as spreading code and address code, communication system performance
To be greatly affected.Walsh code has good autocorrelation performance as address code and is zero everywhere
Cross correlation.But, each code character of Walsh code due to the equal reason of shared spectral bandwidth, thus
Cannot function as spreading code.So pseudo-random sequence PN to be used as spread spectrum code, and for address code, this
Patent uses Walsh coding.
In spread spectrum module 203, each sensing data source is each individually takies a channel 2031, wherein
(S11(t), S12(t)..., S1n(t)) ..., (Sm1(t), Sm2(t)..., Smn(t)) represent different types of data group.
In every set type, each channel carries out mould 2032 from different Walsh sequence codes respectively.Due in system not
The data rate to be transmitted with sensor data source is varied, and the Walsh function of same order
Limited amount, therefore allows the Walsh function the using different rank different channels data to different rates
Stream is modulated.Then each signal in often group is added and carries out orthogonal multiplex 2033.The most each data
Type group combines different spread spectrum PN codes and carries out signal spread-spectrum process 2034, by information signal to be transmitted
Spread spectrum becomes broadband signal, and the bandwidth at this moment transmitting signal is far longer than the raw information being transmitted
The bandwidth of signal, has been greatly reinforced anti-artificial disturbance in stress wave transmitting procedure, the interference of anti-arrowband, anti-many
The ability of footpath interference.Spread spectrum code can include m code sequence, Gold code sequence and M code sequence etc..Each letter
Road signal is superimposed by after spread processing, forms composite signal S(t)2035。
In despreading module 211, each data type group is de-spread by the PN code first passing through correspondence
Frequently preliminary treatment 2111, in the most each data type group, each receives the Walsh that channel is corresponding with itself
Code carries out synchronizing convolution 2112, it is achieved auto-correlation demodulation 2113, can recover the signal that each channel sends
2114。
Although the embodiment that disclosed herein is as above, but described content is only to facilitate understand this
The embodiment invented and use, is not limited to the present invention.In any the technical field of the invention
Technical staff, on the premise of without departing from the spirit and scope that disclosed herein, can implement
And make any amendment and change in details in form, but the scope of patent protection of the present invention, still must be with institute
Attached claims are defined in the range of standard.
Claims (3)
1. one kind based on PZT multipoint communication system in solid structure, it is characterised in that this system
Including: sensor, intelligent sensing circuit, acoustic-electrical transducer, signal processing system；Described
Sensor, for producing different data types, including numeral, text and video type；
Intelligent sensing circuit, for embedding the data signal of corresponding sensor；
Acoustic-electrical transducer, produces elastic stress wave, for transmitting described different data type；
The data of collection for gathering the data signal of described sensor, and are carried out by signal processing system
Time reversal processes, and the data signal after processing time reversal carries out carrier modulation, after described modulation
Signal carries binary signal information, finally obtains respective sensor data at receiving terminal；
Described signal processing system uses Direct Sequence Spread Spectrum Communication technology, and uses skew quaternary phase shift key
Control modulation realizes multi-sensor information modulation；
Described spread spectrum uses orthogonal geocoding and quasi-orthogonal intersection to distinguish the number of different sensors
According to passage, using spread spectrum code is m code, Gold code and M code；
Described orthogonal geocoding is in solid dielectric multi-point, and the Walsh code of application different rank is full
The different transmission rates of foot different channels.
2. one kind realizes multicast routing method based on PZT in solid structure, it is characterised in that described
Method includes:
Using solid structure as medium emission detectable signal；
Receive detectable signal, and the detectable signal received is carried out time reversal process and spread processing；
Sent by transmitting terminal again after being modulated, utilize the time-reversal focusing of ripple, improve signal intensity, gram
Take serious channel frequency dispersion, multipath and multi-modal problem that elastic wave propagation causes, it is achieved multichannel senses
The synchronization of information does not interfere with each other communication；
Described spread processing is: the data of sensor encode in solid structure becomes binary signal, uses
The frequency spectrum of different pseudo-extended code broadening difference sensing sources data signals；
Signal after time reversal is carried out carrier modulation, and the signal after modulation carries binary signal information；
Encourage, by binary signal, the PZT sheet that described sensor is corresponding, make PZT sheet produce stress wave,
And stress wave is transferred to receiving terminal；
The signal received is carried out carrier wave demodulation by receiving terminal, and by corresponding with sensor for the signal after demodulation
Pseudo-spread spectrum code carry out coherently despreading process, it is thus achieved that sensor signal.
The most according to claim 2 in solid structure, realize multicast routing method based on PZT,
It is characterized in that, described sensor is to there being a corresponding spread spectrum code.
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102507655A (en) * | 2011-10-24 | 2012-06-20 | 沈阳建筑大学 | Method for monitoring compaction of concrete-filled steel tube structure based on piezoelectric intelligent aggregate |
| CN103105434A (en) * | 2013-01-17 | 2013-05-15 | 华南理工大学 | Elongated metal structure damage detecting method and system based on active acoustic emission method |
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| GB2459091B (en) * | 2008-04-07 | 2012-05-23 | Thales Holdings Uk Plc | Method and system for acoustic imaging |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102507655A (en) * | 2011-10-24 | 2012-06-20 | 沈阳建筑大学 | Method for monitoring compaction of concrete-filled steel tube structure based on piezoelectric intelligent aggregate |
| CN103105434A (en) * | 2013-01-17 | 2013-05-15 | 华南理工大学 | Elongated metal structure damage detecting method and system based on active acoustic emission method |
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