CN109450538A - Suitable for power transmission line in high altitude region inspection visible light communication square synchronization system - Google Patents
Suitable for power transmission line in high altitude region inspection visible light communication square synchronization system Download PDFInfo
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- CN109450538A CN109450538A CN201811457635.9A CN201811457635A CN109450538A CN 109450538 A CN109450538 A CN 109450538A CN 201811457635 A CN201811457635 A CN 201811457635A CN 109450538 A CN109450538 A CN 109450538A
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- signal
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- carrier synchronization
- synchronization unit
- quadratic
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/11—Arrangements specific to free-space transmission, i.e. transmission through air or vacuum
- H04B10/114—Indoor or close-range type systems
- H04B10/116—Visible light communication
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
- H04L27/2655—Synchronisation arrangements
- H04L27/2657—Carrier synchronisation
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- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Optical Communication System (AREA)
- Synchronisation In Digital Transmission Systems (AREA)
Abstract
One kind being suitable for power transmission line in high altitude region inspection visible light communication square synchronization system, include while receiving the first quadratic loop carrier synchronization unit of line-of-sight signal respectively and receiving the second quadratic loop carrier synchronization unit of non line of sight signal, the first quadratic loop carrier synchronization unit and the second quadratic loop carrier synchronization unit is for carrying out Phase synchronization processing to received signal respectively, output signal after the first quadratic loop carrier synchronization cell processing, which is added with the output signal after the second quadratic loop carrier synchronization cell processing by adder, constitutes overall digital output signal.The present invention takes full advantage of the signal resource of non line of sight link portions, carrier synchronization is realized in visible light communication field, the present invention during line data-logging visible light communication not by the interference of high-tension line complex electromagnetic environment, it is easily achieved linear network topology structure, suitable for the networking of transmission line of electricity, can be applied in the polling transmission line of high altitude localities.
Description
Technical field
The present invention relates to a kind of visible light communication square synchronization systems.It is defeated to be suitable for high altitude localities more particularly to one kind
Electric line inspection visible light communication square synchronization system
Background technique
The area such as Qinghai-Tibet Platean height above sea level, mountain area is more, natural environment is severe, to save valuable land resource, high pressure
Transmission line of electricity is built by the mountain mostly, and traditional ultra-high-tension power transmission line manual inspection mode is by larger restriction.Unmanned plane inspection etc.
New technology has played important function in power grid maintenance and in checking.Since unmanned plane is in high-speed flight, channel circumstance is not
Disconnected transformation, the communication system of single-rate, which real-time can not be obtained, changes its transmission speed according to different channel conditions, is unfavorable for
The promotion of efficiency of transmission.In addition more serious Doppler effect can be generated when unmanned plane high-speed flight cause bigger symbol
Between interfere, while ultra-high-tension power transmission line nearby has strong electromagnetic interference, therefore traditional communication mode limitation is larger.
Core as visible light communication technology, it is seen that the transmission mode of optical channel and carrier wave closely related therewith are same
Step is always people's priority fields of study.The on-link mode (OLM) of indoor communication system can be divided into two o'clock.First point is to see transmitting
Whether machine and receiver orient.So-called orientation is an angle problem in fact, for transmitter, if the light of its transmitting
The light beam of beam divergence angle very little, sending is almost parallel, then is called directional transmitter；If the visual field scope of receiver is very
It is small, then it is called direction-finding receiver.If sending and receiving both ends just establish a link, this link when being aligned both for orientation
It is known as directional link.Rather than directional link uses wide-angle Receiver And Transmitter.There are also a kind of links, in transmitter
With there is one to be non-directional in receiver, and the other is orientation, it is this be referred to as compounded link.Second point is according to two
Classify according between transmitter and receiver with the presence or absence of undisturbed sighting distance (line of sight, LOS) at end.Depending on
It is removed away from the light that receiver in link (line of sight, LOS) receives not reflected in the presence of being launched by transmitter
Light；And non line of sight (non line of sight, NLOS) link is usually transmitter against ceiling transmitting optical signal, is passed through
The a series of of wall reflect up to receiver.In conclusion the link mode of wireless light communication is generally divided into following six kinds: orientation
Line of sight link；Non-directional line of sight link；Mix line of sight link；Orient non line of sight link；Non-directional non line of sight link；Mix non-view
Away from link.
In digital communication systems, synchronizing is critically important technical problem, and realize on difficult point, net synchronization capability it is excellent
The bad performance for directly determining communication system.
In a communications system, after information is mapped by ad hoc fashion, transmitter is modulated, and passes through letter with certain frequency
Road is sent, and the signal that receiver receives will receive noise jamming in channel, in order to accurately recover transmission data, receiver
Groundwork be exactly to provide synchronization system for judgment device, realize the estimation and correction of data parameters.Receiver to signal into
When row demodulation, needs therefrom to extract and receive signal carrier with frequently with the coherent carrier of phase, the extraction of this coherent carrier
Journey is exactly carrier synchronization, and carrier synchronization is the basis of coherent demodulation.Digital information in communication system is a string of continuous symbols
Sequence is generally selected in the optimum sampling moment of code-element period, that is, eye figure when carrying out bit decision to the signal demodulated
Open maximum position.Receiving end must generate a bit timing pulse sequence synchronous with modulated signal chip clock is received,
It samples and adjudicates for symbol.
Carrier synchronization can be divided into pilot tone system and direct method two major classes, and insertion pilot tone system needs in the information sequence of transmission
It is inserted into pilot frequency sequence, this just needs system to distribute certain power to pilot signal, therefore distributes to the power of information sequence
It is corresponding to reduce, and direct method, it directly can restore carrier wave from reception signal, not need transmission pilot tone, save frequency band, this is right
In very nervous frequency spectrum resource be highly important.And square around-France is exactly one of direct carrier synchronization method, tradition is flat
Square ring carrier synchronization method is made of square law device, phaselocked loop and two-divider.Wherein phaselocked loop is equivalent to one very narrow
Narrow band filter, required carrier component can be extracted well, have it is good tracking, narrow-band filtering and memory function
Energy.
Summary of the invention
The technical problem to be solved by the invention is to provide a kind of frequency spectrums for taking full advantage of LOS channel Yu NLOS channel
Resource, improve VISIBLE LIGHT SYSTEM band efficiency is suitable for power transmission line in high altitude region inspection visible light communication square together
Step system.
The technical scheme adopted by the invention is that: it is flat that one kind being suitable for power transmission line in high altitude region inspection visible light communication
Square synchronization system includes while receiving the first quadratic loop carrier synchronization unit of line-of-sight signal respectively and receiving non line of sight signal
The second quadratic loop carrier synchronization unit, the first quadratic loop carrier synchronization unit and the second quadratic loop carrier synchronization unit
For carrying out Phase synchronization processing to received signal respectively, the output after the first quadratic loop carrier synchronization cell processing
Signal is added by adder with the output signal after the second quadratic loop carrier synchronization cell processing and constitutes overall digital output letter
Number.
The first quadratic loop carrier synchronization unit and the second quadratic loop carrier synchronization cellular construction is identical, includes
Have: square-law module, bandpass filter, phaselocked loop and the two-divider being sequentially connected in series, wherein the square-law module of institute's art
Input terminal receive line-of-sight signal or non line of sight signal, for carrying out square to the signal received, export one group of time-domain signal,
The output end of the two-divider constitutes the output of the first quadratic loop carrier synchronization unit or the second quadratic loop carrier synchronization unit
End.
The phaselocked loop includes the phase discriminator, loop filter and digital controlled oscillator being sequentially connected in series, the mirror
The output end of the input terminal connection bandpass filter of phase device, the output end of the digital controlled oscillator are separately connected the input of phase discriminator
The input terminal at end and two-divider, wherein the phase discriminator is to the output signal of digital controlled oscillator and the output of bandpass filter
Signal carries out phase demodulation, generates a phase error signal, the loop filter filter out receive high-frequency signal in signal and
Noise takes out the frequency of slowly varying DC component control digital controlled oscillator, and the mould that will be received by bilinear transformation
Quasi- signal is mapped to numeric field, and digital controlled oscillator is generated ideal by the output of fixed frequency control word and loop filter
Changeable frequency sine and cosine signal.
The digital controlled oscillator includes the phase accumulator being sequentially connected in series, phase register, phase adder
With cordic algorithm module, wherein the input terminal of the phase accumulator is separately connected the output end and phase of loop filter
The output end of bit register, the input terminal of the phase adder are also connected with phase control words, the cordic algorithm module
Output end is separately connected the input terminal of phase discriminator and the input terminal of two-divider.
Of the invention is suitable for power transmission line in high altitude region inspection visible light communication square synchronization system, takes full advantage of
The signal resource of the part non line of sight link (non line of sight, Non-LOS), realizes load in visible light communication field
Wave is synchronous, and present invention visible light communication during line data-logging is easy to real not by the interference of high-tension line complex electromagnetic environment
Now linear network topology structure can be applied in the polling transmission line of high altitude localities suitable for the networking of transmission line of electricity.
The present invention has the advantage that
1. being based on visible light communication technology, two-way carrier synchronization method is used, is taken full advantage of through NLOS channel part
The signal divided.Improve band efficiency.
2. digital controlled oscillator part uses the novel numerical control oscillator based on cordic algorithm, it is based on looking into compared to tradition
It looks for the digital controlled oscillator of table to compare, improves reaction speed and working efficiency.
3. there is no increase for the complexity of the synchronization system compared to traditional visible light communication synchronization module.
In conclusion the power transmission line in high altitude region inspection visible light communication square synchronization system that is suitable for of the invention has
There is good application prospect.
Detailed description of the invention
Fig. 1 is the whole frame that the present invention is suitable for power transmission line in high altitude region inspection visible light communication square synchronization system
Figure；
Fig. 2 is the composition block diagram of quadratic loop carrier synchronization unit in the present invention；
Fig. 3 is the composition block diagram of digital controlled oscillator in the present invention.
In figure
1: the first quadratic loop carrier synchronization unit, 2: the second quadratic loop carrier synchronization unit
3: adder 4: square-law module
5: bandpass filter 6: phaselocked loop
61: phase discriminator 62: loop filter
63: digital controlled oscillator 631: phase accumulator
632: phase register 633: phase adder
634:CORDIC algoritic module 635: phase control words
7: two-divider
Specific embodiment
Power transmission line in high altitude region inspection visible light communication is suitable for of the invention below with reference to embodiment and attached drawing
Square synchronization system is described in detail.
As shown in Figure 1, of the invention is suitable for power transmission line in high altitude region inspection visible light communication square synchronization system,
It is characterised in that it includes have while receiving respectively the first quadratic loop carrier synchronization unit 1 of line-of-sight signal (LOS) and receive non-view
The second quadratic loop carrier synchronization unit 2 away from signal (NLOS), the first quadratic loop carrier synchronization unit 1 and second square
Ring carrier synchronization unit 2 is for carrying out Phase synchronization processing, the first quadratic loop carrier synchronization to received signal respectively
Treated that output signal is added by adder 3 for treated the output signal of unit 1 and the second quadratic loop carrier synchronization unit 2
Constitute overall digital output signal.
As shown in Fig. 2, 2 structure of the first quadratic loop carrier synchronization unit 1 and the second quadratic loop carrier synchronization unit
It is identical, include: square-law module 4, bandpass filter 5, phaselocked loop 6 and the two-divider 7 being sequentially connected in series, wherein
The input terminal of the square-law module 4 of institute's art receives line-of-sight signal or non line of sight signal, for being carried out square to the signal received,
One group of time-domain signal is exported, the output end of the two-divider 7 constitutes the first quadratic loop carrier synchronization unit 1 or the second quadratic loop
The output end of carrier synchronization unit 2.
The phaselocked loop 6 includes the phase discriminator 61, loop filter 62 and digital controlled oscillator 63 being sequentially connected in series,
The output end of the input terminal connection bandpass filter 5 of the phase discriminator 61, the output end of the digital controlled oscillator 63 are separately connected
The input terminal of phase discriminator 61 and the input terminal of two-divider 7, wherein output signal of the phase discriminator 61 to digital controlled oscillator 63
Phase demodulation is carried out with the output signal of bandpass filter 5, generates a phase error signal, the loop filter 62, which filters out, to be connect
High-frequency signal and noise in the collection of letters number, take out the frequency of slowly varying DC component control digital controlled oscillator 63, and pass through
The analog signal received is mapped to numeric field by bilinear transformation, and digital controlled oscillator 63 passes through fixed frequency control word and ring
The output of path filter 62 generates the sine and cosine signal of ideal changeable frequency.
As shown in figure 3, the digital controlled oscillator 63 includes that the phase accumulator 631 being sequentially connected in series, phase are posted
Storage 632, phase adder 633 and cordic algorithm module 634, wherein the input terminal of the phase accumulator 631 connects respectively
The output end of loop filter 62 and the output end of phase register 632 are connect, the input terminal of the phase adder 633 also connects
Phase control words 635 are connect, the output end of the cordic algorithm module 634 is separately connected the input terminal and two divided-frequency of phase discriminator 61
The input terminal of device 7.
Illustrate that of the invention to be suitable for power transmission line in high altitude region inspection visible light communication square same below by example
Step system.
Visible light channel is divided into LOS and two kinds of NLOS, this, which makes the impulse response of channel form two, certain phase difference
Peak value.And the luminous flux of visible light communication is concentrated mainly on LOS channel, therefore traditional method of synchronization mainly believes LOS
Road part synchronizes, and present invention employs the synchronization units of dual carrier synchronous versions as shown in Figure 1, respectively in not
The two parts of signals in same-phase section synchronizes.
According to fig. 2, first the receiving end two-way quadratic loop carrier synchronization unit of signal respectively to corresponding phase field into
Row simultaneously operating.It is now assumed that input signal is that bpsk signal is carried out through square-law module first after it is input to synchronization unit
Square, it obtains:
Have when u (t) is rectangular pulseAssuming that phaselocked loop locking phase is in 2 ωc's
In frequency, the output signal of digital controlled oscillator isWhereinIt is the estimation to input signal phase
Value.
Due to phase discriminator use multiplier realize therefore obtained phase error signal for
The signal obtained after loop filter filters out high fdrequency component are as follows:It can thus be appreciated that loop filtering
The output of device is only related with phase.The system function of loop filter are as follows:
The key of this part is C1 in the value of C2, and thus phase difference has analog quantity to map in order to can be by digital controlled oscillator
The digital quantity of identification.
Traditional digital controlled oscillator using look-up table generate just, cosine signal, in the situation more demanding to output accuracy
Under, need to occupy a large amount of hardware store resource, and restriction of the output speed by chip RAM reading speed.The present invention adopts
Cordic algorithm can by just, the calculating of cosine be decomposed into a series of plus-minus and shift operation, algorithm structure is simpler
It is single, it is suitble to hardware realization, while occupying less hardware store resource.
Claims (4)
1. one kind is suitable for power transmission line in high altitude region inspection visible light communication square synchronization system, which is characterized in that including
There is while receiving respectively the first quadratic loop carrier synchronization unit (1) of line-of-sight signal and receives the second quadratic loop of non line of sight signal
Carrier synchronization unit (2), the first quadratic loop carrier synchronization unit (1) and the second quadratic loop carrier synchronization unit (2) are used
In carrying out Phase synchronization processing to received signal respectively, that treated is defeated for the first quadratic loop carrier synchronization unit (1)
Signal and the second quadratic loop carrier synchronization unit (2) treated output signal are added composition entirety number by adder (3) out
Word output signal.
2. according to claim 1 be suitable for power transmission line in high altitude region inspection visible light communication square synchronization system,
It is characterized in that, the first quadratic loop carrier synchronization unit (1) and second quadratic loop carrier synchronization unit (2) structure phase
Together, include: square-law module (4), bandpass filter (5), phaselocked loop (6) and the two-divider (7) being sequentially connected in series,
Wherein, the input terminal of the square-law module (4) of institute's art receives line-of-sight signal or non line of sight signal, for the signal received into
Row square, exports one group of time-domain signal, and the output end of the two-divider (7) constitutes the first quadratic loop carrier synchronization unit (1)
Or second quadratic loop carrier synchronization unit (2) output end.
3. according to claim 2 be suitable for power transmission line in high altitude region inspection visible light communication square synchronization system,
It is characterized in that, the phaselocked loop (6) includes the phase discriminator (61), loop filter (62) and numerical control being sequentially connected in series
Oscillator (63), the output end of input terminal connection bandpass filter (5) of the phase discriminator (61), the digital controlled oscillator (63)
Output end be separately connected the input terminal of phase discriminator (61) and the input terminal of two-divider (7), wherein the phase discriminator (61) is right
The output signal of digital controlled oscillator (63) and the output signal of bandpass filter (5) carry out phase demodulation, generate a phase error letter
Number, the loop filter (62) filters out the high-frequency signal and noise received in signal, takes out slowly varying DC component
The frequency of digital controlled oscillator (63) is controlled, and the analog signal received is mapped to by numeric field, numerical control by bilinear transformation
Oscillator (63) generates the sine of ideal changeable frequency by the output of fixed frequency control word and loop filter (62)
With cosine signal.
4. according to claim 3 be suitable for power transmission line in high altitude region inspection visible light communication square synchronization system,
It is characterized in that, the digital controlled oscillator (63) includes phase accumulator (631), the phase register being sequentially connected in series
(632), phase adder (633) and cordic algorithm module (634), wherein the input terminal of the phase accumulator (631) point
The output end of other linkloop filter (62) and the output end of phase register (632), the phase adder (633)
Input terminal is also connected with phase control words, and the output end of the cordic algorithm module (634) is separately connected the defeated of phase discriminator (61)
Enter the input terminal at end and two-divider (7).
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811457635.9A CN109450538B (en) | 2018-11-30 | 2018-11-30 | Visible light communication square synchronization system suitable for power transmission line inspection in high-altitude area |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811457635.9A CN109450538B (en) | 2018-11-30 | 2018-11-30 | Visible light communication square synchronization system suitable for power transmission line inspection in high-altitude area |
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| CN109450538A true CN109450538A (en) | 2019-03-08 |
| CN109450538B CN109450538B (en) | 2021-06-04 |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101150343A (en) * | 2006-09-20 | 2008-03-26 | 华为技术有限公司 | A MIMO mobile communication method and system |
| CN107359935A (en) * | 2017-07-11 | 2017-11-17 | 中国科学技术大学 | A kind of ultraviolet scatter communication system of non line of sight based on step-by-step counting and its method |
| CN108494714A (en) * | 2018-03-22 | 2018-09-04 | 桂林电子科技大学 | A method of quickly overcoming the GMSK coherent demodulations of Doppler frequency shift |
-
2018
- 2018-11-30 CN CN201811457635.9A patent/CN109450538B/en not_active Expired - Fee Related
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101150343A (en) * | 2006-09-20 | 2008-03-26 | 华为技术有限公司 | A MIMO mobile communication method and system |
| CN107359935A (en) * | 2017-07-11 | 2017-11-17 | 中国科学技术大学 | A kind of ultraviolet scatter communication system of non line of sight based on step-by-step counting and its method |
| CN108494714A (en) * | 2018-03-22 | 2018-09-04 | 桂林电子科技大学 | A method of quickly overcoming the GMSK coherent demodulations of Doppler frequency shift |
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