CN104113501B - Modulator, demodulator, modulation method and demodulation method for low-frequency magnetic induction communication - Google Patents
Modulator, demodulator, modulation method and demodulation method for low-frequency magnetic induction communication Download PDFInfo
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- CN104113501B CN104113501B CN201410276980.8A CN201410276980A CN104113501B CN 104113501 B CN104113501 B CN 104113501B CN 201410276980 A CN201410276980 A CN 201410276980A CN 104113501 B CN104113501 B CN 104113501B
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Abstract
The invention provides a modulator, demodulator, modulation method and demodulation method for low-frequency magnetic induction communication. Therefore, problems of mutual restriction of a bandwidth and a Q value of the existing low-frequency magnetic induction communication transmitting terminal, low low-frequency communication rate, low integration degree and flexibility of the hardwire demodulation mode of the receiving terminal, and large calculation amount of the software demodulation mode in the prior art can be solved. According to the modulator, use data are successively processed by channel coding, BPSK digital modulation, D/A conversion and power amplification and then are inputted into a first series connection resonance loop; voltage physical reversing of the two ends of a first capacitor in the resonance loop is carried out at the time of phase changing of the loop current signal of the first series connection resonance loop, thereby avoiding the loop current signal attenuation. Therefore, the modulation signal bandwidth can be substantially improved on the premise that the Q value is maintained to be high; and the communication rate is improved.
Description
Technical field
The invention belongs to the modulation-demodulation technique of the communications field, more particularly to a kind of manipulator of low-frequency magnetic inductive communication,
Demodulator and modulator approach and demodulation method.
Background technology
At present, the communication of low frequency magnetic strength due to its antenna size it is little, multipath effect is not received in communication process, propagation delay and decline
The impact that falls and be widely used in subsurface communication and underground communication.But the channel under low frequency band is a low rate
Channel, how maximally effective utilization communication channel is the difficult point in current LF communication technology.
In prior art, common low-frequency resonant circuit is generally required in bandwidth and Q in the transmitting terminal of low frequency magnetic strength communication
Accepted or rejected between value, it is desirable to which increasing resonant bandwidth must be to reduce the Q-value of circuit as cost, and vice versa, therefore typically all
It is to choose suitable bandwidth and Q-value to meet the condition of communication after balance, bandwidth and Q-value cannot simultaneously take maximum.Additionally, low
When the receiving terminal of frequency magnetic strength communication carries out signal capture, local replica also reduces the real-time of communication with the related operation of lead code
Property, and existing hardware demodulation mode hardware integration degree is low, it is not high to demodulate motility, is to solve the problem, carries in prior art
Go out the scheme of software demodulation, with the demodulator circuit that monolithic system instead of complexity, so not only increase the collection of hardware system
Cheng Du further increases the motility of demodulation, but compared to traditional circuit type hardware demodulation, the shortcoming of existing software demodulation
It is that amount of calculation is larger, needs longer process time.
In sum, the existing bandwidth of low frequency magnetic strength communication transmitting terminal and the value of Q-value are mutually limited and cause low frequency to lead to
Letter speed is low, and the hardware demodulation mode integrated level of receiving terminal is low, motility is not high, and software demodulation mode exist it is computationally intensive
Problem.
The content of the invention
The present invention provides a kind of manipulator of low-frequency magnetic inductive communication, demodulator and modulator approach and demodulation method, is used for
Solve the existing bandwidth of low frequency magnetic strength communication transmitting terminal and the value of Q-value is mutually limited and causes LF communication speed low, receive
The hardware demodulation mode integrated level at end is low, motility is not high, and software demodulation mode there is a problem of it is computationally intensive.
To solve the above problems, present invention firstly provides a kind of manipulator of low-frequency magnetic inductive communication, including：First ARM
Processor, phase-shifting full-bridge BPSK modulation circuits and low-frequency magnetic induced emission antenna；The phase-shifting full-bridge BPSK modulation circuits it is defeated
Enter end to be connected with first arm processor by FSMC buses, outfan connects the low-frequency magnetic induced emission antenna；It is described
First arm processor carries out chnnel coding to user data, obtains sequence of symhols to be sent and by the sequence of symhols Jing
FSMC buses are sent to the phase-shifting full-bridge BPSK modulation circuits；The phase-shifting full-bridge BPSK modulation circuits are in the code element sequence for receiving
Lead code 01010101 is added before row and the sequence of symhols to receiving is modified：Whenever 0101010 just inserts one after
Individual 0, and amended sequence of symhols is carried out successively to obtain the first simulation after BPSK digital modulation, D/A conversions and power amplification
Modulated signal；The port for exporting first modulated-analog signal passes sequentially through first electric capacity and the low frequency magnetic induction
Penetrate antenna and constitute the first series resonant tank, and the first series resonance described in the phase-shifting full-bridge BPSK modulation circuit real-time judges
Whether the phase place of the loop current signals in loop will occur the change of 180 degree, if so, then in first series resonant tank
The moment of the phase change of loop current signals is by the first electric capacity both end voltage physics sex reversal；The low frequency magnetic induction is sent out
Penetrate antenna and the current signal for flowing through itself is converted to into low-frequency magnetic field signal transmission.
Preferably, the phase-shifting full-bridge BPSK modulation circuits include：BPSK digital modulation modules, D/A modular converters, power
Amplifier, first switch, second switch, the 3rd switch, the 4th switch, on-off circuit control module, not gate logical device and
First electric capacity；The input of the BPSK digital modulation modules is connected by FSMC buses with first arm processor,
Outfan is connected with the input of the D/A modular converters；The BPSK digital modulation modules are before the sequence of symhols for receiving
Add lead code 01010101 and the sequence of symhols to receiving is modified：Whenever 0101010 just inserts one 0 after；And
Amended sequence of symhols is carried out into BPSK digital modulation；The outfan of the D/A modular converters and the power amplifier
Input connects；The outfan of the power amplifier is connected with one end of the first switch, the 3rd switch simultaneously, and described the
The other end of the other end of one switch and the 3rd switch is by first capacitance connection；The first switch and the first electric capacity
Connection end is also connected with one end of the second switch, the other end of the second switch and the low-frequency magnetic induced emission antenna
Coil one end connection, the low-frequency magnetic induced emission antenna the coil other end ground connection；3rd switch and the first electric capacity
Connection end also be connected with one end of the described 4th switch, the other end connection second switch of the 4th switch and described
The coil connecting terminal of low-frequency magnetic induced emission antenna；The on-off circuit control module connects with the BPSK digital modulation modules
Connect, and its control output end is simultaneously defeated with what the input of the not gate logical device, the control end of first switch, the 4th switched
Enter end connection, the outfan of the not gate logical device is while the control end and the control end of the 3rd switch with the second switch
Connection；The on-off circuit control module according to the BPSK digital modulation modules to sent sequence of symhols modulation feelings
Condition, in the phase change 180 degree of the loop current signals of first series resonant tank, will be imparted to the not gate
The digital signal of logical device carries out 0-1/1-0 switchings, to control the first switch, second switch, and the 3rd switch, the 4th opens
Close transformation current switch states.
Preferably, the BPSK digital modulation modules and on-off circuit control module are realized using FPGA modes.
Preferably, the phase-shifting full-bridge BPSK modulation circuits also include that first resistor, isolating amplifier circuit, an A/D turn
Mold changing block and current zero detection module；The low-frequency magnetic induced emission antenna it is not another with the coil that the second switch is connected
One end is grounded by the first resistor, and the isolating amplifier circuit input connects the line of the low-frequency magnetic induced emission antenna
The connection end of circle and first resistor, outfan connects the input of an A/D modular converters；The first A/D moduluss of conversion
The outfan of block connects the input of the current zero detection module, the outfan of the current zero detection module with it is described
On-off circuit control module connects；The current zero detection module by an A/D modular converters, isolating amplifier circuit, the
One resistance and low-frequency magnetic induced emission antenna institute connection circuit detect the direction of the loop current of first series resonant tank, and
First series resonant tank loop current will zero-acrross ing moment notify the on-off circuit control module；The switch
The loop current of the first series resonant tank that circuit control module is sent according to the current zero detection module will zero passage
Notify, whether the current signal element to be sent of judgement and the upper code element for just having sent are identical, if it is not, then in the described first string
The loop current zero-acrross ing moment of connection resonant tank will be imparted to the digital signal of the not gate logical device to carry out 0-1/1-0 and cuts
Change.
The present invention also provides a kind of tune of the low-frequency magnetic inductive communication of the manipulator corresponding to above-mentioned low-frequency magnetic inductive communication
Device processed, including：Low frequency magnetic induction reception antenna, the second electric capacity, impedance-matching transformer, active filter, programmable amplifying circuit,
2nd A/D modular converters, BPSK demodulation modules and the second arm processor；The low frequency magnetic induction reception antenna is according to low-frequency magnetic
The alternating magnetic field that the low-frequency magnetic field signal that the manipulator of inductive communication sends is formed induces the second analog current modulated signal；Institute
The primary coil for stating low frequency magnetic induction reception antenna, the second electric capacity and impedance-matching transformer is composed in series the second series resonance
Loop, equiva lent impedance of the impedance-matching transformer in second series resonant tank in purely resistive and with the low frequency
Magnetic induction reception antenna internal resistance is equal, and second series resonant tank is used for low frequency magnetic induction reception antenna output
Second analog current modulated signal carries out frequency-selecting；3rd analog current of the secondary coil output of the impedance-matching transformer is adjusted
Signal processed active filter filtering described in Jing successively, programmable amplifying circuit described in Jing carries out signal amplification, and the 2nd A/D described in Jing turns
Mold changing block is converted to digital modulation signals, and BPSK demodulation modules are sent to described second described in after being demodulated into digital demodulated signal
Arm processor carries out error detection, and second arm processor is supplied to correct digital demodulated signal as user data
User；Wherein, the BPSK demodulation modules are used to demodulate the signal that lead code is 01010101, and the BPSK demodulation modules are adopted
FPGA modes are realized.
Preferably, the BPSK demodulation modules in the demodulator include：Carrier recovery unit, correlation demodulation unit,
Lead code recognition unit, clock sample unit and thresholding judging unit；The carrier recovery unit adopts costa rings calculating side
Method, the phase contrast of the signal carrier of the digital modulation signals exported with the 2nd A/D modular converters by local carrier is to carrying
Wave phase is corrected in real time, and revised carrier wave is sent to into the correlation demodulation unit；The correlation demodulation unit bag
Include multiplier and FIR low pass filter, the multiplier respectively with outfan, the carrier wave of the 2nd A/D modular converters
The input connection of the outfan of recovery unit and the FIR low pass filter, the multiplier is to the carrier auxiliary list
The carrier signal of unit's output and the digital modulation signals of the 2nd A/D modular converters output carry out being sent to the FIR after multiplication low
Bandpass filter, the FIR low pass filter is filtered to input signal and obtains baseband signal and export to the lead code to know
Other unit；The lead code of the baseband signal that the lead code recognition unit is exported to FIR low pass filter is identified, and is obtained with this
Go out the phase place of sampling clock and be supplied to the clock sample unit and thresholding judging unit；The clock sample unit with it is described
Carrier recovery unit connects, and the phase place of the sampling clock for being sent according to the lead code recognition unit is extensive to the carrier wave
The carrier signal of multiple unit output carries out clock sampling, obtains the frequency of sampling clock and provides it to the thresholding judgement list
Unit；The thresholding judging unit using the sampling clock for receiving phase place and the frequency of sampling clock, obtain sampling clock and with
This clock carries out threshold judgement to the baseband signal, demodulates digital demodulated signal.
The manipulator of the low-frequency magnetic inductive communication provided corresponding to the present invention, the present invention also provides a kind of low frequency magnetic induction and leads to
The modulator approach of letter, the method comprising the steps of：
S11：Chnnel coding is carried out to user data, sequence of symhols to be sent is obtained；
S12：BPSK digital modulation is carried out to the sequence of symhols to be sent, and by the numeral after modulation in modulated process
The lead code of signal is set as 01010101, and the sequence of symhols to receiving is modified：Whenever 0101010 just inserts after
One 0, obtain BPSK digital modulation signals；
S13：D/A conversions are carried out to the BPSK digital modulation signals, BPSK modulated-analog signals are obtained；
S14：Power amplification is carried out to the BPSK modulated-analog signals and obtains the first modulated-analog signal；
S15：By first modulated-analog signal input one by export first modulated-analog signal port, first
In first series resonant tank of electric capacity and low-frequency magnetic induced emission antenna composition, and the first series resonance described in real-time judge is returned
Whether the phase place of the loop current signals on road will occur the change of 180 degree, if so, then change in the phase place of the loop current signals
The moment of change is by the first electric capacity both end voltage physics sex reversal；
S16：The current signal for flowing through itself is converted to low-frequency magnetic field signal and is sent by the low-frequency magnetic induced emission antenna.
Preferably, in the modulator approach of the low-frequency magnetic inductive communication, judge that first series resonance is returned described in S15
Whether the phase place of the loop current signals on road be by the method for the change that 180 degree occurs：Judge current signal element to be sent
Whether the upper code element for just having sent is identical, if it is not, then the loop current signals of first series resonant tank are in code element
There is phase shift in the current zero-crossing point changed near the moment.
The demodulator of the low-frequency magnetic inductive communication provided corresponding to the present invention, the present invention also provides a kind of low frequency magnetic induction and leads to
The demodulation method of letter, including step：
S21：The low-frequency magnetic field signal shape that low frequency magnetic induction reception antenna sends according to the manipulator of low-frequency magnetic inductive communication
Into alternating magnetic field induce the second analog current modulated signal；
S22：The 3rd analog current modulated signal that frequency-selecting is obtained is carried out to the second analog current modulated signal；
S23：Carry out active power filtering, signal amplification, A/D conversions successively to the 3rd analog current modulated signal, obtain
Lead code is 01010101 digital modulation signals；
S24：It is that 01010101 digital modulation signals carry out BPSK demodulation to lead code, and to code that demodulation is obtained
Metasequence is modified：Often run into 01010100 and just remove last 0, obtain digital demodulated signal；
S25：Error detection is carried out to the digital demodulated signal, and using correct digital demodulated signal as user data
It is supplied to user.
Preferably, it is that 01010101 digital modulation signals are carried out to lead code described in S24 in above-mentioned demodulation method
BPSK demodulation method be：
S241：Using costa ring computational methods, by the phase of local carrier and the signal carrier of the digital modulation signals
Potential difference is corrected in real time to carrier phase；
S242：Multiplying is carried out by the carrier signal for obtaining the digital modulation signals and S241, and by multiplication
Operation result carries out FIR low-pass filtering, recovers baseband signal；
S243：The lead code 01010101 of the baseband signal is identified, and is just gone running into 01010100 every time
Fall last 0, finally draw the phase place of sampling clock, and the carrier signal obtained to S241 is when carrying out clock sampling and obtaining sampling
The frequency of clock；
S244：Sampling clock is obtained using the phase place of the sampling clock and the frequency of sampling clock, and with adopting for obtaining
Sample clock carries out threshold judgement to the baseband signal, and changes code element, demodulates digital demodulated signal.
Preferably, in the S243 lead code 01010101 of the baseband signal is carried out using finite automaton state machine
Recognize, concrete recognition methodss are：
S31：State machine initial state value is set as 0, represents that lead code is to be identified, if recognizing base band letter in a state
Number rising edge then enter state 1；
S32：On the premise of state 1, if recognize baseband signal next hopping edge be trailing edge and with it is previous
The time interval of rising edge is between (1-m) T to (1+m) T, then into state 2, if surpassing with the time interval of previous rising edge
Cross (1+m) T and occur without trailing edge, then return state 0；Wherein m is fixed value and 0<m<1/2, T is a code-element period；
S33：On the premise of state 2, if recognize baseband signal next hopping edge be rising edge and with it is previous
The time interval of trailing edge is the state 3 that then enters between (1-m) T to (1+m) T, if being with the time interval of previous trailing edge
Occur more than (1+m) T and without rising edge, then return state 0；Wherein m is fixed value and 0<m<1/2, T is a code-element period；
S34：The process of repeat step S32-S33, every time detection increases 1 by then state value, and otherwise state value returns 0, directly
To state 7 is entered, the lead code of the baseband signal is recognized successfully.
Preferably, the method for the hopping edge of identification baseband signal is during the S31-S34：To be currently needed for what is recognized
The data point markers of baseband signal are n-th point, and Ruo Dang (n-N/2) o'clock to the point between (n-k) point to bear and less than setting
Fixed negative threshold value, and the point between (n+k) o'clock to (n+N/2) puts is just and higher than in the positive threshold value of setting, then it is assumed that currently
Occur rising edge at the data point for needing the baseband signal for recognizing, and suspend identification base within the following 1/2 code-element period time
The hopping edge of band signal；Wherein, k is constant and 0<k<N/4, N are the corresponding sampling number of code-element period.
The above-mentioned technical proposal of the present invention has the beneficial effect that：
The present invention provide low-frequency magnetic inductive communication manipulator and modulator approach in, by low-frequency magnetic induced emission antenna,
First electric capacity and loop resistance constitute series resonant circuit, and resonant capacitance (i.e. the first electric capacity) is located in " H " bridge switch circuit,
Transmission of symbols change is the signal phase shift moment, can control the first electric capacity by " H " bridge switch circuit and be inverted in circuit,
Allow signal voltage direction to be consistent with the course of discharge of the first electric capacity, so as to avoid the decay of current signal, believe modulation
Number maintain maximum resonance state always in resonant tank, modulated signal can be greatly improved on the premise of higher q values are kept
Bandwidth, effectively raise the speed of LF communication, solve the bandwidth and Q-value of existing low frequency magnetic strength communication transmitting terminal
The problem that value is mutually limited and traffic rate is low.Additionally, the demodulation of the corresponding low-frequency magnetic inductive communication of present invention offer
Device and demodulation method are demodulated using digital demodulation mode, can fast and accurately capture lead code, it is ensured that demodulation it is real-time
Property, increased the motility of demodulation and improve the integrated level of hardware, leading Code acquisition is carried out using pattern recognition in demodulation, count
Calculation amount is far below traditional correlation capturing, is conducive to the low power dissipation design of whole system.
Description of the drawings
Fig. 1 is a kind of modulator structure schematic diagram of low-frequency magnetic inductive communication provided in an embodiment of the present invention；
Fig. 2 is that the preferred real-time architecture of one of which of the manipulator of low-frequency magnetic inductive communication provided in an embodiment of the present invention shows
It is intended to
Fig. 3 is the phase-shifting full-bridge BPSK modulated process schematic diagrams in circuit shown in Fig. 2；
Fig. 4 is preferable to carry out structural representation for the another kind of the manipulator of low-frequency magnetic inductive communication；
The modulator approach flow chart of the low-frequency magnetic inductive communication that Fig. 5 is provided for the present invention；
A kind of demodulator structure schematic diagram of low-frequency magnetic inductive communication that Fig. 6 is provided for the present invention；
Fig. 7 is a kind of preferred real-time architecture schematic diagram of the demodulator of low-frequency magnetic inductive communication shown in Fig. 6；
The demodulation method flow chart of the low-frequency magnetic inductive communication that Fig. 8 is provided for the present invention.
[accompanying drawing main components description of symbols]
1st, the first arm processor；
2nd, phase-shifting full-bridge BPSK modulation circuits；
3rd, low-frequency magnetic induced emission antenna；
4th, BPSK digital modulation modules；
5th, D/A modular converters；
6th, power amplifier；
7th, on-off circuit control module；
8th, not gate logical device；
9th, isolating amplifier circuit；
10th, an A/D modular converters；
11st, current zero detection module；
12nd, low frequency magnetic induction reception antenna；
13rd, impedance-matching transformer；
14th, active filter；
15th, programmable amplifying circuit；
16th, the 2nd A/D modular converters；
17th, BPSK demodulation modules；
18th, the second arm processor；
19th, carrier recovery unit；
20th, correlation demodulation unit；
21st, lead code recognition unit；
22nd, clock sample unit；
23rd, thresholding judging unit；
24th, multiplier；
25th, FIR low pass filter；
K1, first switch；
K2, second switch；
K3, the 3rd switch；
K4, the 4th switch；
C1, the first electric capacity；
R1, first resistor；
C2, the second electric capacity.
Specific embodiment
To make the technical problem to be solved in the present invention, technical scheme and advantage clearer, below in conjunction with accompanying drawing and tool
Body embodiment is described in detail.
Fig. 1 show a kind of modulator structure schematic diagram of low-frequency magnetic inductive communication provided in an embodiment of the present invention, such as Fig. 1
Shown in, the manipulator includes：First arm processor 1, phase-shifting full-bridge BPSK modulation circuits 2 and low-frequency magnetic induced emission antenna
3.Wherein, the input of phase-shifting full-bridge BPSK modulation circuits 2 is connected by FSMC buses with the first arm processor 1, and outfan connects
Connect low-frequency magnetic induced emission antenna 3.First arm processor 1 carries out chnnel coding to user data, obtains code element sequence to be sent
Sequence of symhols Jing FSMC buses are simultaneously sent to phase-shifting full-bridge BPSK modulation circuits 2, and be responsible for this manipulator and other equipment by row
Interface protocol.Phase-shifting full-bridge BPSK modulation circuits 2 added lead code 01010101 and to receiving before the sequence of symhols for receiving
To sequence of symhols modify：Whenever 0101010 just inserts one 0 to avoid the occurrence of and lead code identical sequence after
Row, and amended sequence of symhols is carried out successively to obtain the first simulation tune after BPSK digital modulation, D/A conversions and power amplification
Signal processed；The port for exporting the first modulated-analog signal passes sequentially through 3 groups of first electric capacity and low-frequency magnetic induced emission antenna
Into the first series resonant tank, and the loop current of the first series resonant tank of real-time judge of phase-shifting full-bridge BPSK modulation circuits 2
Whether the phase place of signal will occur the change of 180 degree, if so, then the first series resonant tank loop current signals phase place
The moment of change is by the first electric capacity both end voltage physics sex reversal.Low-frequency magnetic induced emission antenna 3 is believed the electric current of itself is flow through
Number be converted to low-frequency magnetic field signal transmission.
In due to traditional BPSK modulation, because transmitting terminal resonant tank limits bandwidth, the electric current in resonant tank exists
180 ° of phase shift points can be attenuated, i.e., in the series resonant circuit course of work, energy is transmitted back and forth in electric capacity with inductance,
Loop current zero-acrross ing moment, energy is stored entirely in resonant tank electric capacity, and subsequent time electric capacity will be discharged, electric discharge electricity
Before stream direction and zero passage conversely, and under BPSK modulation systems, signal can occur 180 ° of phase shifts at the current over-zero moment, cause work(
The signal voltage of output is put with the voltage direction of electric capacity conversely, the two can make loop current signals decay after cancelling out each other.This
By by the first electric capacity both end voltage physics sex reversal, allowing the voltage and signal voltage of the first electric capacity at the signal phase shift moment in bright
Direction is consistent, this to be entered by physics mode so as to realize that signal phase place in the case of unattenuated is quickly changed
The mode of row modulation can greatly improve the bandwidth of modulated signal on the premise of higher q values are kept.
Fig. 2 show the one of which of the manipulator of low-frequency magnetic inductive communication provided in an embodiment of the present invention and preferably ties in real time
Structure schematic diagram, as shown in Figure 2, in the manipulator of the low-frequency magnetic inductive communication, phase-shifting full-bridge BPSK modulation circuits include：BPSK
Digital modulation module 4, D/A modular converters 5, power amplifier 6, first switch K1, second switch K2, the 3rd switch K3, the 4th
Switch K4, on-off circuit control module 7, the electric capacity C1 of not gate logical device 8 and first.
Wherein, the input of BPSK digital modulation modules 4 is connected by FSMC buses with the first arm processor 1, outfan
It is connected with the input of D/A modular converters 5；BPSK digital modulation modules 4 added lead code before the sequence of symhols for receiving
01010101 and the sequence of symhols to receiving modify：Whenever 0101010 just after insert one 0 with avoid the occurrence of with it is front
Leading code identical sequence, and amended sequence of symhols is carried out into BPSK digital modulation, and the digital signal after modulation is sent
To D/A modular converters 5.The outfan of D/A modular converters 5 is connected with the input of power amplifier 6；Power amplifier 6 it is defeated
Go out end to be connected with one end of first switch K1, the 3rd switch K3 simultaneously, the other end of first switch K1 and the 3rd switchs the another of K3
One end is connected by the first electric capacity C1；The connection end of first switch K1 and the first electric capacity C1 also connects with one end of second switch K2
Connect, the other end of second switch K2 is connected with coil one end of low-frequency magnetic induced emission antenna 3, low-frequency magnetic induced emission antenna 3
The coil other end ground connection；The connection end of the 3rd switch K3 and the first electric capacity C1 is also connected with one end of the 4th switch K4, and the 4th
The other end connection second switch K2 and the coil connecting terminal of low-frequency magnetic induced emission antenna 3 of switch K4.On-off circuit controls mould
Block 7 is connected with BPSK digital modulation modules 4, and its control output end is while input, the first switch of NAND gate logical device 8
The input connection of the control end of K1, the 4th switch K4, the outfan of not gate logical device 8 is while the control with second switch K2
End and the control end connection of the 3rd switch K3.On-off circuit control module 7 and BPSK digital modulation modules 4 connect, and according to
BPSK digital modulation modules 4 are believed to sent the modulation case of sequence of symhols in the loop current of the first series resonant tank
Number phase change 180 degree moment, will be imparted to the digital signal of not gate logical device 8 carries out 0-1/1-0 switchings, with control
First switch K1, second switch K2, the 3rd switch K3, the 4th switch K4 transformation current switch states.Wherein, power amplifier 6
For a kind of low noise LF power amplifier, to the BPSK modulated signals for exporting D/A modular converters 5 carry out power amplification with
Drive transmitting antenna loop.
And by Fig. 2 it will be evident that due to first switch K1 and the control end connection not gate logical device 8 of the 4th switch K4
Input, and the outfan of the switch K3 connections of second switch K2 and the 3rd not gate logical device 8, therefore first switch K1 and the
The on off state of four switch K4 is forever consistent, and the on off state of the switch K3 of second switch K2 and the 3rd is opened unanimously and with first forever
The on off state for closing the switch K4 of K1 and the 4th is contrary.From unlike conventional resonant circuit, the first electric capacity in Fig. 2 is located at " H "
In bridge switch circuit, therefore, by on-off circuit control module 7 and not gate logical device 8 it is controllable by first, second, third,
" H " bridge switch circuit of 4th switch composition, so as to realize allowing the first electric capacity C1 to enter at the series resonant tank current over-zero moment
The quick reversion of row, allows the first electric capacity C1 back discharges, realizes the 180 degree phase shift of loop current.
Fig. 3 is the phase-shifting full-bridge BPSK modulated process schematic diagrams in circuit shown in Fig. 2.It is normal humorous as can see from Figure 2
Center of percussion resonant capacitance can successively experience positive charge, back discharge, reverse charging, positive electric discharge four-stage, circuit shown in Fig. 2
In, the original state of 4 electrical switches is K1, K4 conducting, and K2, K3 disconnect, and now the first electric capacity C1 is positive accesses circuit.Due to
There is the current over-zero moment after the first electric capacity reverse charging terminates in the change of first time code element, now power amplifier 6 is exported
There are 180 ° of phase shifts in voltage, now control " H " bridge switch circuit and be switched to K1, K4 disconnection, K2, K3 conducting, so that the first electric capacity
C1 reversely accesses circuit, and by this reverse turn operation physically 180 ° of loop current phase shift is made, so as to artificially allow resonance just
Often go on.
Preferably, as shown in Fig. 2 BPSK digital modulation modules 4 and on-off circuit control module 7 adopt FPGA mode realities
It is existing, and can realize in same FPGA coprocessors.For example, FPGA coprocessors can adopt altera corp
Cyclone IV family chips.
Preferably, in order that on-off circuit control module 7 can more accurately control the switch in " H " bridge switch circuit
Switching action, can carry out detection to carry out assist control, specifically such as using the direction of the loop current to series resonant tank
The another kind of the manipulator of the low-frequency magnetic inductive communication of Fig. 4 is preferable to carry out shown in structural representation, phase-shifting full-bridge BPSK modulation electricity
Road also includes first resistor R1, isolating amplifier circuit 9, an A/D modular converters 10 and current zero detection module 11.Wherein,
The coil other end not being connected with second switch K2 of low-frequency magnetic induced emission antenna 3 is grounded by first resistor R1, and isolation is put
The coil of the big input of circuit 9 connection low-frequency magnetic induced emission antenna 3 and the connection end of first resistor R1, outfan connection first
The input of A/D modular converters 10；The input of the outfan connection current zero detection module 11 of the first A/D modular converters 10
End, the outfan of current zero detection module 11 is connected with on-off circuit control module 7.In Fig. 4, current zero detection module 11
By an A/D modular converters 10, the 3 connection circuit inspections of isolating amplifier circuit 9, first resistor R1 and low-frequency magnetic induced emission antenna
The direction of the loop current of the first series resonant tank is surveyed, and the loop current in the first series resonant tank will zero-acrross ing moment
Notify on-off circuit control module 7.On-off circuit control module 7 is humorous according to the first series connection that current zero detection module 11 is sent
Shake loop loop current will zero passage notify, judge whether are current signal element to be sent and the upper code element that just sent
It is identical, if it is not, then the first series resonant tank loop current zero-acrross ing moment will be imparted to not gate logical device 8 numeral letter
Number carry out 0-1/1-0 switchings.
The modulated terminal of the low-frequency magnetic inductive communication provided corresponding to the present invention, the present invention also provides a kind of low frequency magnetic induction and leads to
The modulator approach of letter, as shown in figure 5, the modulator approach of the low-frequency magnetic inductive communication of present invention offer includes step：
S11：Chnnel coding is carried out to user data, sequence of symhols to be sent is obtained；
S12：BPSK digital modulation is carried out to sent sequence of symhols, and by the digital signal after modulation in modulated process
Lead code be set as 01010101, and the sequence of symhols to receiving is modified：Whenever 0101010 just inserts one after
0, obtain BPSK digital modulation signals；
S13：D/A conversions are carried out to BPSK digital modulation signals, BPSK modulated-analog signals are obtained；
S14：Power amplification is carried out to BPSK modulated-analog signals and obtains the first modulated-analog signal；
S15：By the first modulated-analog signal input one by the output port of the first modulated-analog signal, the first electric capacity and low
In first series resonant tank of frequency magnetic induction transmitting antenna composition, and the loop current of the series resonant tank of real-time judge first
Whether the phase place of signal will occur the change of 180 degree, if so, then electric by first at the moment of the phase change of loop current signals
Hold both end voltage physics sex reversal；
S16：The current signal for flowing through itself is converted to low-frequency magnetic field signal and is sent by low-frequency magnetic induced emission antenna.
Preferably, in the modulator approach of above-mentioned low-frequency magnetic inductive communication, the first series resonant tank is judged in step S15
Whether the phase place of loop current signals be by the method for the change that 180 degree occurs：Judge current signal element to be sent and just
Whether the upper code element for having sent is identical, if it is not, then the loop current signals of the first series resonant tank change in code element
There is phase shift in the current zero-crossing point near the moment.
Corresponding to the manipulator of low-frequency magnetic inductive communication provided in an embodiment of the present invention, the embodiment of the present invention also provides one kind
The demodulator of low-frequency magnetic inductive communication as shown in Figure 6, the demodulator includes：Low frequency magnetic induction reception antenna 12, the second electric capacity
C2, impedance-matching transformer 13, active filter 14, programmable amplifying circuit 15, the 2nd A/D modular converters 16, BPSK solution mode transfer
The arm processor 18 of block 17 and second.
In the demodulator of low-frequency magnetic inductive communication shown in Fig. 6, low frequency magnetic induction reception antenna 12 is logical according to low frequency magnetic induction
The alternating magnetic field that the low-frequency magnetic field signal that the manipulator of letter sends is formed induces the second analog current modulated signal.Low frequency magnetic strength
The primary coil for answering reception antenna 12, the second electric capacity C2 and impedance-matching transformer 13 is composed in series the second series resonance time
Road.Second series resonant tank is used to select the second analog current modulated signal of the output of low frequency magnetic induction reception antenna 12
Frequently, to suppress a part of noise, equiva lent impedance of the impedance-matching transformer 13 in the second series resonant tank in purely resistive and
It is equal with low frequency magnetic induction 12 internal resistances of reception antenna, so as to reach the impedance matching between amplifying circuit and resonance circuit, so as to incite somebody to action
The signal of reception is coupled to late-class circuit with peak power.3rd simulation electricity of the secondary coil output of impedance-matching transformer 13
Successively Jing active filters 14 are filtered stream modulated signal, and Jing after programmable amplifying circuit 15 carries out signal amplification the 2nd A/D is sent to
Modular converter 16 carries out A/D conversions.This is, due in practical communication, with the change of transmission power and communication distance, to receive
To signal power also can change, if directly carrying out A/D conversions, when the shadow that the fainter quantization error of signal is brought
Sound is bigger, in order to ignore quantization error, should may amplify the signal to certain stable amplitude before A/D conversions, therefore this is in
Programmable amplifying circuit 15 is set between the A/D modular converters 16 of active filter 14 and the 2nd.Subsequently, the 2nd A/D modular converters 16
The analogue signal of input is converted to into digital modulation signals, then is sent Jing after BPSK demodulation modules 17 are demodulated into digital demodulated signal
Error detection is carried out to the second arm processor 18, final second arm processor 18 is using correct digital demodulated signal as user
Data are supplied to user.Wherein, BPSK demodulation modules 17 are used to demodulate the signal that lead code is 01010101, it is preferable that BPSK
Demodulation module 17 is realized using FPGA coprocessor modes, and FPGA coprocessors can also in real time be adjusted according to current demand signal amplitude
The signal amplification factor of section programmable amplifying circuit 15, so that signal amplitude is stable in certain scope.
Fig. 7 is a kind of preferred real-time architecture schematic diagram of the demodulator of low-frequency magnetic inductive communication shown in Fig. 6, wherein, BPSK
Demodulation module 17 includes：Carrier recovery unit 19, correlation demodulation unit 20, lead code recognition unit 21, clock sample unit 22
With thresholding judging unit 23.Wherein,
Carrier recovery unit 19 adopts costa ring computational methods, is exported with the 2nd A/D modular converters 16 by local carrier
The phase contrast of signal carrier of digital modulation signals carrier phase is corrected in real time, and revised carrier wave is sent to
Correlation demodulation unit 20.
Correlation demodulation unit 20 includes multiplier 24 and FIR low pass filter 25, and multiplier 24 is changed respectively with the 2nd A/D
The input connection of the outfan, the outfan of carrier recovery unit 19 and FIR low pass filter 25 of module 16, multiplier 24
The digital modulation signals of carrier signal and the output of the 2nd A/D modular converters 16 to the output of carrier recovery unit 19 are carried out after multiplication
It is sent to FIR low pass filter 25, FIR low pass filter 25 is filtered to input signal and obtains baseband signal and export to front
Leading code recognition unit 21.
The lead code of the baseband signal that lead code recognition unit 21 is exported to FIR low pass filter 25 is identified, with this
Draw the phase place of sampling clock and be supplied to clock sample unit 22 and thresholding judging unit 23.
Clock sample unit 22 is connected with carrier recovery unit 19, for the sampling sent according to lead code recognition unit 21
The phase place of clock, to the carrier signal of the output of carrier recovery unit 19 clock sampling is carried out, and is obtained the frequency of sampling clock and is incited somebody to action
It is supplied to thresholding judging unit 23.
Thresholding judging unit 23 obtains sampling clock simultaneously using the phase place and the frequency of sampling clock of the sampling clock for receiving
Threshold judgement is carried out to baseband signal with this clock, digital demodulated signal is demodulated.
The demodulator of the low-frequency magnetic inductive communication provided corresponding to the present invention, the embodiment of the present invention also provides a kind of low-frequency magnetic
The demodulation method of inductive communication, is illustrated in figure 8 the demodulation method flow chart of this low-frequency magnetic inductive communication, including step：
S21：The low-frequency magnetic field signal shape that low frequency magnetic induction reception antenna sends according to the manipulator of low-frequency magnetic inductive communication
Into alternating magnetic field induce the second analog current modulated signal；
S22：The 3rd analog current modulated signal that frequency-selecting is obtained is carried out to the second analog current modulated signal；
S23：Carry out active power filtering, signal amplification, A/D conversions successively to the 3rd analog current modulated signal, obtain leading
Code is 01010101 digital modulation signals；
S24：It is that 01010101 digital modulation signals carry out BPSK demodulation to lead code, and to code element sequence that demodulation is obtained
Row are modified：Often run into 01010100 and just remove last 0, obtain digital demodulated signal；
S25：Error detection is carried out to digital demodulated signal, and is provided correct digital demodulated signal as user data
To user.
Preferably, it is that 01010101 digital modulation signals are carried out to lead code in step S24 in method shown in Fig. 8
BPSK demodulation method be：
S241：Using costa ring computational methods, by local carrier and the phase contrast of the signal carrier of digital modulation signals
Carrier phase is corrected in real time；
S242：Multiplying is carried out by the carrier signal for obtaining digital modulation signals and S241, and by multiplying
As a result FIR low-pass filtering is carried out, baseband signal is recovered；
S243：The lead code 01010101 of baseband signal is identified, and is just removed most running into 01010100 every time
0 afterwards, finally draws the phase place of sampling clock, and the carrier signal obtained to S241 carries out clock sampling and obtains sampling clock
Frequency；
S244：Obtain sampling clock using the phase place of sampling clock and the frequency of sampling clock, and with obtain sampling when
Clock carries out threshold judgement to baseband signal, demodulates digital demodulated signal.
Preferably, in step S243 the lead code 01010101 of baseband signal is known using finite automaton state machine
Not, concrete recognition methodss are comprised the following steps：
S31：State machine initial state value is set as 0, represents that lead code is to be identified, if recognizing base band letter in a state
Number rising edge then enter state 1；
S32：On the premise of state 1, if recognize baseband signal next hopping edge be trailing edge and with it is previous
The time interval of rising edge is between (1-m) T to (1+m) T, then into state 2, if surpassing with the time interval of previous rising edge
Cross (1+m) T and occur without trailing edge, then return state 0；Wherein m is fixed value and 0<m<1/2, T is a code-element period；
S33：On the premise of state 2, if recognize baseband signal next hopping edge be rising edge and with it is previous
The time interval of trailing edge is the state 3 that then enters between (1-m) T to (1+m) T, if being with the time interval of previous trailing edge
Occur more than (1+m) T and without rising edge, then return state 0；Wherein m is fixed value and 0<m<1/2, T is a code-element period；
S34：The process of repeat step S32-S33, every time detection increases 1 by then state value, and otherwise state value returns 0, directly
To state 7 is entered, the lead code of baseband signal is recognized successfully.
Preferably, the method for the hopping edge of identification baseband signal is during S31-S34：The base band for recognizing will be currently needed for
The data point markers of signal are n-th point, and Ruo Dang (n-N/2) o'clock to the point between (n-k) point is negative and less than setting
Negative threshold value, and the point between (n+k) o'clock to (n+N/2) puts is just and higher than in the positive threshold value for setting, then it is assumed that it is currently needed for
Occur rising edge at the data point of the baseband signal of identification, and suspend identification base band letter within the following 1/2 code-element period time
Number hopping edge；Wherein, k is constant and 0<k<N/4, N are the corresponding sampling number of code-element period.
The present invention provide low-frequency magnetic inductive communication manipulator and modulator approach in, by low-frequency magnetic induced emission antenna,
First electric capacity and loop resistance constitute series resonant circuit, and resonant capacitance (i.e. the first electric capacity) is located in " H " bridge switch circuit,
Transmission of symbols change is the signal phase shift moment, can control the first electric capacity by " H " bridge switch circuit and be inverted in circuit,
Allow signal voltage direction to be consistent with the course of discharge of the first electric capacity, so as to avoid the decay of current signal, believe modulation
Number maintain maximum resonance state always in resonant tank, modulated signal can be greatly improved on the premise of higher q values are kept
Bandwidth, effectively raise the speed of LF communication, solve the bandwidth and Q-value of existing low frequency magnetic strength communication transmitting terminal
The problem that value is mutually limited and traffic rate is low.Additionally, the demodulation of the corresponding low-frequency magnetic inductive communication of present invention offer
Device and demodulation method are demodulated using digital demodulation mode, can fast and accurately capture lead code, it is ensured that demodulation it is real-time
Property, increased the motility of demodulation and improve the integrated level of hardware, leading Code acquisition is carried out using pattern recognition in demodulation, count
Calculation amount is far below traditional correlation capturing, is conducive to the low power dissipation design of whole system.
The above is the preferred embodiment of the present invention, it is noted that for those skilled in the art
For, on the premise of without departing from principle of the present invention, some improvements and modifications can also be made, these improvements and modifications
Should be regarded as protection scope of the present invention.
Claims (12)
1. a kind of manipulator of low-frequency magnetic inductive communication, it is characterised in that include：First arm processor, phase-shifting full-bridge BPSK is adjusted
Circuit processed and low-frequency magnetic induced emission antenna；The input of the phase-shifting full-bridge BPSK modulation circuits by FSMC buses with it is described
First arm processor connects, and outfan connects the low-frequency magnetic induced emission antenna；
First arm processor carries out chnnel coding to user data, obtains sequence of symhols to be sent and by the code element
Sequence Jing FSMC buses are sent to the phase-shifting full-bridge BPSK modulation circuits；
The phase-shifting full-bridge BPSK modulation circuits added before the sequence of symhols for receiving lead code 01010101 and to receiving
Sequence of symhols is modified：Whenever 0101010 just inserts one 0 after, and amended sequence of symhols is carried out successively
The first modulated-analog signal is obtained after BPSK digital modulation, D/A conversions and power amplification；Export first modulated-analog signal
Port pass sequentially through first electric capacity and the low-frequency magnetic induced emission antenna and constitute the first series resonant tank, it is and described
Whether the phase place of the loop current signals of the first series resonant tank described in phase-shifting full-bridge BPSK modulation circuit real-time judges will be sent out
The change of raw 180 degree, if so, then first series resonant tank loop current signals phase change moment by institute
State the first electric capacity both end voltage physics sex reversal；
The current signal for flowing through itself is converted to low-frequency magnetic field signal and is sent by the low-frequency magnetic induced emission antenna.
2. the manipulator of low-frequency magnetic inductive communication as claimed in claim 1, it is characterised in that the phase-shifting full-bridge BPSK modulation
Circuit includes：BPSK digital modulation modules, D/A modular converters, power amplifier, first switch, second switch, the 3rd switch,
4th switch, on-off circuit control module, not gate logical device and first electric capacity；
The input of the BPSK digital modulation modules is connected by FSMC buses with first arm processor, outfan with
The input connection of the D/A modular converters；The BPSK digital modulation modules added leading before the sequence of symhols for receiving
Code 01010101 and the sequence of symhols to receiving modify：Whenever 0101010 just inserts one 0 after；And after changing
Sequence of symhols carry out BPSK digital modulation；
The outfan of the D/A modular converters is connected with the input of the power amplifier；The output of the power amplifier
End be connected with one end of the first switch, the 3rd switch simultaneously, the other end of the first switch and the 3rd switch it is another
End is by first capacitance connection；The connection end of the first switch and the first electric capacity also connects with one end of the second switch
Connect, the other end of the second switch is connected with coil one end of the low-frequency magnetic induced emission antenna, the low frequency magnetic induction
The coil other end ground connection of transmitting antenna；One end that the connection end of the 3rd switch and the first electric capacity also switchs with the described 4th
Connection, the other end of the 4th switch connects the coil connection of the second switch and the low-frequency magnetic induced emission antenna
End；
The on-off circuit control module is connected with the BPSK digital modulation modules, and its control output end is simultaneously non-with described
The input of gate logic device, the control end of first switch, the 4th switch input connection, the not gate logical device it is defeated
Go out end to be connected with the control end of the second switch and the control end of the 3rd switch simultaneously；
The on-off circuit control module according to the BPSK digital modulation modules to sent sequence of symhols modulation case,
In the phase change 180 degree of the loop current signals of first series resonant tank, will be imparted to the not gate and patrol
Collecting the digital signal of device carries out 0-1/1-0 switchings, to control the first switch, second switch, the 3rd switch, the 4th switch
Transformation current switch states.
3. the manipulator of low-frequency magnetic inductive communication as claimed in claim 2, it is characterised in that the BPSK digital modulation modules
Realized using FPGA modes with on-off circuit control module.
4. the manipulator of low-frequency magnetic inductive communication as claimed in claim 3, it is characterised in that the phase-shifting full-bridge BPSK modulation
Circuit also includes first resistor, isolating amplifier circuit, an A/D modular converters and current zero detection module；The low-frequency magnetic
The coil other end not being connected with the second switch of induced emission antenna is grounded by the first resistor, and the isolation is put
Big circuit input end connects the coil of the low-frequency magnetic induced emission antenna and the connection end of first resistor, and outfan connection is described
The input of the first A/D modular converters；The outfan of the first A/D modular converters connects the current zero detection module
Input, the outfan of the current zero detection module is connected with the on-off circuit control module；
The current zero detection module passes through an A/D modular converters, isolating amplifier circuit, first resistor and low frequency magnetic induction
Transmitting antenna institute connection circuit detects the direction of the loop current of first series resonant tank, and in first series resonance
The loop current in loop will zero-acrross ing moment notify the on-off circuit control module；
The loop of the first series resonant tank that the on-off circuit control module is sent according to the current zero detection module
Electric current will zero passage notify, judge whether current signal element to be sent and the upper code element that just sent identical, if it is not, then
The digital signal that will be imparted to the not gate logical device in the loop current zero-acrross ing moment of first series resonant tank enters
Row 0-1/1-0 switches.
5. a kind of demodulator of low-frequency magnetic inductive communication, it is characterised in that include：Low frequency magnetic induction reception antenna, the second electric capacity,
Impedance-matching transformer, active filter, programmable amplifying circuit, the 2nd A/D modular converters, BPSK demodulation modules and the 2nd ARM
Processor；
The low frequency magnetic induction reception antenna is formed according to the low-frequency magnetic field signal that the manipulator of low-frequency magnetic inductive communication sends
Alternating magnetic field induces the second analog current modulated signal；
The primary coil of the low frequency magnetic induction reception antenna, the second electric capacity and impedance-matching transformer is composed in series the second string
Connection resonant tank, equiva lent impedance of the impedance-matching transformer in second series resonant tank in purely resistive and with institute
State low frequency magnetic induction reception antenna internal resistance equal, second series resonant tank is used for the low frequency magnetic induction reception antenna
Second analog current modulated signal of output carries out frequency-selecting；
The 3rd analog current modulated signal active power filtering described in Jing successively of the secondary coil output of the impedance-matching transformer
Device is filtered, and programmable amplifying circuit described in Jing carries out signal amplification, and the 2nd A/D modular converters described in Jing are converted to digital modulation letter
Number, the BPSK demodulation modules described in are sent to second arm processor and carry out error detection after being demodulated into digital demodulated signal,
Correct digital demodulated signal is supplied to user by second arm processor as user data；
Wherein, the BPSK demodulation modules are used to demodulate the signal that lead code is 01010101, and the BPSK demodulation modules are adopted
FPGA modes are realized.
6. the demodulator of low-frequency magnetic inductive communication as claimed in claim 5, it is characterised in that the BPSK demodulation modules bag
Include：Carrier recovery unit, correlation demodulation unit, lead code recognition unit, clock sample unit and thresholding judging unit；
The carrier recovery unit adopts costa ring computational methods, is exported with the 2nd A/D modular converters by local carrier
The phase contrast of signal carrier of digital modulation signals carrier phase is corrected in real time, and revised carrier wave is sent to
The correlation demodulation unit；
The correlation demodulation unit includes multiplier and FIR low pass filter, and the multiplier is changed respectively with the 2nd A/D
The input connection of the outfan of module, the outfan of the carrier recovery unit and the FIR low pass filter, it is described to take advantage of
The carrier signal and the digital modulation signals of the 2nd A/D modular converters output that musical instruments used in a Buddhist or Taoist mass is exported to the carrier recovery unit is taken advantage of
The FIR low pass filter is sent to after method, the FIR low pass filter is filtered to input signal and obtains baseband signal simultaneously
Export to the lead code recognition unit；
The lead code of the baseband signal that the lead code recognition unit is exported to FIR low pass filter is identified, and is drawn with this
The phase place of sampling clock is simultaneously supplied to the clock sample unit and thresholding judging unit；
The clock sample unit is connected with the carrier recovery unit, for adopting for being sent according to the lead code recognition unit
The phase place of sample clock, to the carrier signal of the carrier recovery unit output clock sampling is carried out, and obtains the frequency of sampling clock
And provide it to the thresholding judging unit；
The thresholding judging unit using the sampling clock for receiving phase place and the frequency of sampling clock, obtain sampling clock and with
This clock carries out threshold judgement to the baseband signal, demodulates digital demodulated signal.
7. a kind of modulator approach of low-frequency magnetic inductive communication, it is characterised in that including step：
S11：Chnnel coding is carried out to user data, sequence of symhols to be sent is obtained；
S12：BPSK digital modulation is carried out to the sequence of symhols to be sent, and by the digital signal after modulation in modulated process
Lead code be set as 01010101, and the sequence of symhols to receiving is modified：Whenever 0101010 just inserts one after
0, obtain BPSK digital modulation signals；
S13：D/A conversions are carried out to the BPSK digital modulation signals, BPSK modulated-analog signals are obtained；
S14：Power amplification is carried out to the BPSK modulated-analog signals and obtains the first modulated-analog signal；
S15：By first modulated-analog signal input one by port, the first electric capacity for exporting first modulated-analog signal
In the first series resonant tank of low-frequency magnetic induced emission antenna composition, and the first series resonant tank described in real-time judge
Whether the phase place of loop current signals will occur the change of 180 degree, if so, then in the phase change of the loop current signals
Moment is by the first electric capacity both end voltage physics sex reversal；
S16：The current signal for flowing through itself is converted to low-frequency magnetic field signal and is sent by the low-frequency magnetic induced emission antenna.
8. the modulator approach of low-frequency magnetic inductive communication as claimed in claim 7, it is characterised in that judge described in S15 described
Whether the phase place of the loop current signals of the first series resonant tank be by the method for the change that 180 degree occurs：Judgement is currently treated
Whether the signal element of transmission and the upper code element for just having sent are identical, if it is not, the then loop of first series resonant tank
There is phase shift in current zero-crossing point of the current signal near code element changes the moment.
9. a kind of demodulation method of low-frequency magnetic inductive communication, it is characterised in that including step：
S21：Low frequency magnetic induction reception antenna is formed according to the low-frequency magnetic field signal that the manipulator of low-frequency magnetic inductive communication sends
Alternating magnetic field induces the second analog current modulated signal；
S22：The 3rd analog current modulated signal that frequency-selecting is obtained is carried out to the second analog current modulated signal；
S23：Carry out active power filtering, signal amplification, A/D conversions successively to the 3rd analog current modulated signal, obtain leading
Code is 01010101 digital modulation signals；
S24：It is that 01010101 digital modulation signals carry out BPSK demodulation to lead code, and to code element sequence that demodulation is obtained
Row are modified：Often run into 01010100 and just remove last 0, obtain digital demodulated signal；
S25：Error detection is carried out to the digital demodulated signal, and is provided correct digital demodulated signal as user data
To user.
10. the demodulation method of low-frequency magnetic inductive communication as claimed in claim 9, it is characterised in that be to lead code described in S24
01010101 digital modulation signals carry out the method for BPSK demodulation：
S241：Using costa ring computational methods, by the phase contrast of local carrier and the signal carrier of the digital modulation signals
Carrier phase is corrected in real time；
S242：Multiplying is carried out by the carrier signal for obtaining the digital modulation signals and S241, and by multiplying
As a result FIR low-pass filtering is carried out, baseband signal is recovered；
S243：The lead code 01010101 of the baseband signal is identified, and is just removed most running into 01010100 every time
0 afterwards, finally draws the phase place of sampling clock, and the carrier signal obtained to S241 carries out clock sampling and obtains sampling clock
Frequency；
S244：Obtain sampling clock using the phase place of the sampling clock and the frequency of sampling clock, and with obtain sampling when
Clock carries out threshold judgement to the baseband signal, and changes code element, demodulates digital demodulated signal.
The demodulation method of 11. low-frequency magnetic inductive communications as claimed in claim 10, it is characterised in that using having in the S243
Limit automatic state machine is identified to the lead code 01010101 of the baseband signal, and concrete recognition methodss are：
S31：State machine initial state value is set as 0, represents that lead code is to be identified, if recognizing baseband signal in a state
Rising edge then enters state 1；
S32：On the premise of state 1, if recognize baseband signal next hopping edge be trailing edge and with previous rising
The time interval on edge is between (1-m) T to (1+m) T, then into state 2, if exceeding (1 with the time interval of previous rising edge
+ m) T and without trailing edge occur, then return state 0；Wherein m is fixed value and 0<m<1/2, T is a code-element period；
S33：On the premise of state 2, if recognize baseband signal next hopping edge be rising edge and with previous decline
The time interval on edge be then into state 3 between (1-m) T to (1+m) T, if with the time interval of previous trailing edge be more than
(1+m) T and without rising edge occur, then return state 0；Wherein m is fixed value and 0<m<1/2, T is a code-element period；
S34：The process of repeat step S32-S33, every time detection increases 1 by then state value, and otherwise state value returns 0, until entering
Enter state 7, the lead code of the baseband signal is recognized successfully.
The demodulation method of 12. low-frequency magnetic inductive communications as claimed in claim 11, it is characterised in that the S31-S34 processes
The method of hopping edge of middle identification baseband signal is：The data point markers that the baseband signal of identification will be currently needed for are n-th point,
Ruo Dang (n-N/2) o'clock is negative and less than the negative threshold value of setting to the point between (n-k) point, and (n+k) o'clock is to (n+N/
2) point between putting is just and higher than in the positive threshold value of setting, then it is assumed that be currently needed for appearance at the data point of the baseband signal of identification
Rising edge, and suspend the hopping edge of identification baseband signal within the following 1/2 code-element period time；Wherein, k is constant and 0<k<
N/4, N are the corresponding sampling number of code-element period.
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Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
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| CN109586768B (en) * | 2018-11-21 | 2020-12-22 | 上海交通大学 | Near field communication method based on magnetic sensor |
| CN111384994B (en) * | 2018-12-28 | 2022-05-10 | 武汉万集信息技术有限公司 | Signal processing method and device |
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| CN114079605B (en) * | 2020-08-13 | 2023-05-23 | 立锜科技股份有限公司 | Communication signal demodulation device and communication signal demodulation method |
| CN114610079B (en) * | 2022-03-09 | 2022-10-18 | 国机传感科技有限公司 | Two-dimensional control method and system based on extremely-low-frequency magnetic sensing |
| CN115790672B (en) * | 2023-02-06 | 2023-05-12 | 国机传感科技有限公司 | Very low frequency electromagnetic wave half-duplex magnetic sensing system and method |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH06237189A (en) * | 1993-02-09 | 1994-08-23 | Mitsubishi Electric Corp | Digital radio communication equipment |
| CN101257467A (en) * | 2007-03-02 | 2008-09-03 | 中兴通讯股份有限公司 | Method for realizing phase overturn-amplitude shift keying digital modulation |
| CN101651953A (en) * | 2008-08-08 | 2010-02-17 | 英特尔公司 | Method and device for generating packet preamble |
| US7688929B2 (en) * | 2003-04-01 | 2010-03-30 | Kingston Technology Corp. | All-digital phase modulator/demodulator using multi-phase clocks and digital PLL |
| CN102195677A (en) * | 2010-03-10 | 2011-09-21 | 青岛东软载波科技股份有限公司 | Receiving circuit, transmitting circuit, microcontroller and power-line carrier communication method |
-
2014
- 2014-06-19 CN CN201410276980.8A patent/CN104113501B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH06237189A (en) * | 1993-02-09 | 1994-08-23 | Mitsubishi Electric Corp | Digital radio communication equipment |
| US7688929B2 (en) * | 2003-04-01 | 2010-03-30 | Kingston Technology Corp. | All-digital phase modulator/demodulator using multi-phase clocks and digital PLL |
| CN101257467A (en) * | 2007-03-02 | 2008-09-03 | 中兴通讯股份有限公司 | Method for realizing phase overturn-amplitude shift keying digital modulation |
| CN101651953A (en) * | 2008-08-08 | 2010-02-17 | 英特尔公司 | Method and device for generating packet preamble |
| CN102195677A (en) * | 2010-03-10 | 2011-09-21 | 青岛东软载波科技股份有限公司 | Receiving circuit, transmitting circuit, microcontroller and power-line carrier communication method |
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