CN108900247A - A kind of wireless light communication pulse interval modulation system and method - Google Patents
A kind of wireless light communication pulse interval modulation system and method Download PDFInfo
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- CN108900247A CN108900247A CN201810676793.7A CN201810676793A CN108900247A CN 108900247 A CN108900247 A CN 108900247A CN 201810676793 A CN201810676793 A CN 201810676793A CN 108900247 A CN108900247 A CN 108900247A
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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
- 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
- H04B10/50—Transmitters
- H04B10/516—Details of coding or modulation
- H04B10/524—Pulse modulation
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- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
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- Optical Communication System (AREA)
Abstract
The present invention relates to pulse modulation technique fields, a kind of wireless light communication pulse interval modulation system is provided, the system hardware is mainly made of modulation and transmission module and reception demodulation module, and the modulation and transmission module includes encoder, transmitting filter module and LED drive module；The receiving module is made of preamplifier, automatic gain system, decision device and decoder；The LED drive module uses white light LEDs, and the front end of the preamplifier is connected with photodetector, and the white light LEDs are communicated with photodetector by direct projection channel；The present invention, which is realized, carries out modulation, demodulation to baseband signal using SDH-PIM, and the maximum feature of this modulation system is exactly that bit synchronization signal and symbol sync signal are not needed when demodulating, and it is more convenient that this feature decodes Demodulation Systems, also can enhanced modulation rate.
Description
Technical field
The present invention relates to pulse modulation technique fields, and in particular to a kind of wireless light communication pulse interval modulation system and side
Method.
Background technique
Light wireless communication has the advantage of fiber optic communication and mobile communication as a kind of novel communication technology, can
Realize broadband transmission, networking maneuverability is not necessarily to frequency application, and electromagnetism interference, good confidentiality, therefore nowadays to wireless
The research of optic communication receives extensive attention.Low-loss light transmission path has not existed in light wireless communication system.Nothing
Linear light communication system link is affected by atmospheric channel by weather, such as：Atmospheric attenuation, light intensity flashing, background radiation
Deng, while there are also optical link alignment issues, and eye-safe limits laser average emitted power, to be mentioned to modulation system
High requirement out.
Due to the low-power consumption requirement of eye-safe and portable mobile communications device, under given error rate condition, light
Source average emitted power should be as low as possible.And indoors in visible light communication, power problems are not present, while meeting indoor photograph
Brightness require under, higher mean power can reduce LED use number it using large power white light LED as light source, send meat
Eye sightless flash signal guarantees normal communication.Currently, the modulation system that light wireless communication is normally applied has：Pulse position
Modulation, ON-OFF keying modulation, digit pulse interval modulation, the modulation demodulation system of communications applications also just become the key of communication
Technology.
Summary of the invention
The technical issues of solution
In view of the deficiencies of the prior art, the present invention provides a kind of wireless light communication pulse interval modulation system and method,
One kind is intended to provide based on the wireless suitable for indoor visible light of the principle foundation for passing empty double end pulse interval modulation (SDH-PIM)
Communication system.
Technical solution
In order to achieve the above object, the present invention is achieved by the following technical programs：
A kind of wireless light communication pulse interval modulation system, the system hardware mainly by modulation and transmission module and receive solution
Mode transfer block composition, the modulation and transmission module includes encoder, transmitting filter module and LED drive module；The reception mould
Block is made of preamplifier, automatic gain system, decision device and decoder；The LED drive module uses white light LEDs, institute
The front end for stating preamplifier is connected with photodetector, and the white light LEDs are led to photodetector by direct projection channel
Letter.
A kind of wireless light communication pulse interval modulation method, operating procedure is mainly by modulating-coding and demodulation coding group
At：
The modulating-coding includes following operating process：
S11：Encoder carries out crystal oscillator to divide to obtain cycle T=Ts/2 clock, and programming is limited using Mealy type
State machine, the effect of clock are to generate 20 states；
S12：Binary data flow is compiled into decimal number k, and compared with 2 (m-1), meets k<2 (m-1) are then generated
Head signal H1, otherwise generates H2；
S13：Correct signal is judged, and completes the transmission of a signal；
The demodulation coding includes following operating process：
S21：Modulation and transmission module signal is received, and the signal of receiving is negated；
S22：It is a signal or unknown signaling by being counted to counter to pulse, and according to count value judgement；
S23：When finding signal, generates count enable signal just to count to the pulse spacing, subtract in a signal
High level width count value can determine binary value, complete demodulation coding.
Further, the encoder and decoder are the core apparatus of modulating system, using programmable logic device,
Its model selects EP2C5T144C8NFPGA.
Further, the automatic gain system is used to enhance the reliability of system, makes when too strong for anti-stop signal
At the saturation of receiver, pulse missing is caused when signal is too weak.
Further, when the demodulation coding, using with unified clock, and the clock cycle is modulator clock
1/10 is even shorter, can facilitate and differentiate head signal and pulse spacing.
Further, the frequency that pulse is counted in demodulation coding is 10 times for sending signal clock frequency, is being counted
It is also easy to produce counting error in the process, when carrying out differentiation signal according to count value, using 1 range come the type of confirmation signal.
Beneficial effect
The present invention provides a kind of wireless light communication pulse interval modulation system and methods, compared with existing well-known technique,
Of the invention has the advantages that：
1, this system is based on the modulation of field programmable gate array FPGA indoor visible light and demodulating system, it uses SDH-
PIM to baseband signal carry out modulation, demodulation, the maximum feature of this modulation system be exactly do not needed when demodulating bit synchronization signal and
Symbol sync signal, it is more convenient that this feature decodes Demodulation Systems, also can enhanced modulation rate.
Detailed description of the invention
In order to more clearly explain the embodiment of the invention or the technical proposal in the existing technology, to embodiment or will show below
There is attached drawing needed in technical description to be briefly described, it should be apparent that, the accompanying drawings in the following description is only this
Some embodiments of invention for those of ordinary skill in the art without creative efforts, can be with
It obtains other drawings based on these drawings.
Fig. 1 is system structure diagram of the invention；
Fig. 2 is modulating-coding flow chart of the invention；
Fig. 3 is demodulation coding flow chart of the invention；
Label in figure respectively represents：1- modulation and transmission module；2- receives demodulation module；3- encoder；4- sends filtering
Device module；5-LED drive module；6- preamplifier；7- decision device；8- decoder；9- photodetector.
Specific embodiment
In order to make the object, technical scheme and advantages of the embodiment of the invention clearer, below in conjunction with the embodiment of the present invention
In attached drawing, technical scheme in the embodiment of the invention is clearly and completely described, it is clear that described embodiment is
A part of the embodiment of the present invention, instead of all the embodiments.Based on the embodiments of the present invention, those of ordinary skill in the art
Every other embodiment obtained without creative efforts, shall fall within the protection scope of the present invention.
A kind of wireless light communication pulse interval modulation system, the system hardware mainly by modulation and transmission module and receive solution
Mode transfer block composition, the modulation and transmission module includes encoder, transmitting filter module and LED drive module；The reception mould
Block is made of preamplifier, automatic gain system, decision device and decoder；The LED drive module uses white light LEDs, institute
The front end for stating preamplifier is connected with photodetector, and the white light LEDs are led to photodetector by direct projection channel
Letter.
A kind of wireless light communication pulse interval modulation method, operating procedure is mainly by modulating-coding and demodulation coding group
At：
The modulating-coding includes following operating process：
S11：Encoder carries out crystal oscillator to divide to obtain cycle T=Ts/2 clock, and programming is limited using Mealy type
State machine, the effect of clock are to generate 20 states；
S12：Binary data flow is compiled into decimal number k, and compared with 2 (m-1), meets k<2 (m-1) are then generated
Head signal H1, otherwise generates H2；
S13：Correct signal is judged, and completes the transmission of a signal；
The demodulation coding includes following operating process：
S21：Modulation and transmission module signal is received, and the signal of receiving is negated；
S22：It is a signal or unknown signaling by being counted to counter to pulse, and according to count value judgement；
S23：When finding signal, generates count enable signal just to count to the pulse spacing, subtract in a signal
High level width count value can determine binary value, complete demodulation coding.
Further, the encoder and decoder are the core apparatus of modulating system, using programmable logic device,
Its model selects EP2C5T144C8NFPGA.
Further, the automatic gain system is used to enhance the reliability of system, makes when too strong for anti-stop signal
At the saturation of receiver, pulse missing is caused when signal is too weak.
Further, when the demodulation coding, using with unified clock, and the clock cycle is modulator clock
1/10 is even shorter, can facilitate and differentiate head signal and pulse spacing.
Further, the frequency that pulse is counted in demodulation coding is 10 times for sending signal clock frequency, is being counted
It is also easy to produce counting error in the process, when carrying out differentiation signal according to count value, using 1 range come the type of confirmation signal.
This system is based on the modulation of field programmable gate array FPGA indoor visible light and demodulating system, it uses SDH-PIM
Modulation, demodulation are carried out to baseband signal, the maximum feature of this modulation system is exactly not need bit synchronization signal and symbol when demodulating
Number synchronization signal, it is more convenient that this feature decodes Demodulation Systems, also can enhanced modulation rate.
It should be noted that, in this document, relational terms such as first and second and the like are used merely to a reality
Body or operation are distinguished with another entity or operation, are deposited without necessarily requiring or implying between these entities or operation
In any actual relationship or order or sequence.Moreover, the terms "include", "comprise" or its any other variant are intended to
Non-exclusive inclusion, so that the process, method, article or equipment including a series of elements is not only wanted including those
Element, but also including other elements that are not explicitly listed, or further include for this process, method, article or equipment
Intrinsic element.In the absence of more restrictions, the element limited by sentence "including a ...", it is not excluded that
There is also other identical elements in process, method, article or equipment including the element.
The above embodiments are merely illustrative of the technical solutions of the present invention, rather than its limitations；Although with reference to the foregoing embodiments
Invention is explained in detail, those skilled in the art should understand that：It still can be to aforementioned each implementation
Technical solution documented by example is modified or equivalent replacement of some of the technical features；And these modification or
Replacement, the spirit and scope for technical solution of various embodiments of the present invention that it does not separate the essence of the corresponding technical solution.
Claims (6)
1. a kind of wireless light communication pulse interval modulation system, which is characterized in that the system hardware mainly sends mould by modulation
Block and reception demodulation module composition, the modulation and transmission module includes encoder, transmitting filter module and LED drive module；
The receiving module is made of preamplifier, automatic gain system, decision device and decoder；The LED drive module uses
White light LEDs, the front end of the preamplifier are connected with photodetector, and the white light LEDs and photodetector pass through direct projection
Channel is communicated.
2. a kind of wireless light communication pulse interval modulation system according to claim 1, which is characterized in that the encoder
It is the core apparatus of modulating system with decoder, using programmable logic device, model selects EP2C5T144C8NFPGA.
3. a kind of wireless light communication pulse interval modulation system according to claim 1, which is characterized in that the automatic increasing
Beneficial system is used to enhance the reliability of system, causes the saturation of receiver when too strong for anti-stop signal, arteries and veins is caused when signal is too weak
Punching is lost.
4. a kind of wireless light communication pulse interval modulation method, which is characterized in that its operating procedure is mainly conciliate by modulating-coding
Adjust decoding composition：
The modulating-coding includes following operating process：
S11：Encoder carries out crystal oscillator to divide to obtain cycle T=Ts/2 clock, and programming uses Mealy type finite state
Machine, the effect of clock are to generate 20 states；
S12：Binary data flow is compiled into decimal number k, and compared with 2 (m-1), meets k<2 (m-1) then generate head letter
Number H1, otherwise generates H2；
S13：Correct signal is judged, and completes the transmission of a signal；
The demodulation coding includes following operating process：
S21：Modulation and transmission module signal is received, and the signal of receiving is negated；
S22：It is a signal or unknown signaling by being counted to counter to pulse, and according to count value judgement；
S23：When finding signal, count enable signal is generated just to count to the pulse spacing, subtract the height electricity in a signal
Flat width count value can determine binary value, complete demodulation coding.
5. a kind of wireless light communication pulse interval modulation method according to claim 4, which is characterized in that the demodulation is translated
When code, using with unified clock, and the clock cycle is the 1/10 even shorter of modulator clock, can facilitate and differentiate head letter
Number and the pulse spacing.
6. a kind of wireless light communication pulse interval modulation method according to claim 4, which is characterized in that in demodulation coding
When to count the frequency of pulse be to send 10 times of signal clock frequency, counting error is also easy to produce in counting process, according to meter
When numerical value carries out differentiation signal, using 1 range come the type of confirmation signal.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114024619A (en) * | 2021-10-26 | 2022-02-08 | 华中科技大学 | Back scattering communication method, device and system based on pulse interval modulation |
Citations (3)
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|---|---|---|---|---|
| CN102215089A (en) * | 2011-05-26 | 2011-10-12 | 王红星 | Wireless optical communication pulse position modulation detection and demodulation method based on least posterior error probability |
| WO2016092790A1 (en) * | 2014-12-11 | 2016-06-16 | 株式会社デンソー | Transmission device |
| US20160269121A1 (en) * | 2015-03-09 | 2016-09-15 | Alcatel-Lucent Usa Inc. | Modulator Biasing For Optical Transmission |
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2018
- 2018-06-27 CN CN201810676793.7A patent/CN108900247A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102215089A (en) * | 2011-05-26 | 2011-10-12 | 王红星 | Wireless optical communication pulse position modulation detection and demodulation method based on least posterior error probability |
| WO2016092790A1 (en) * | 2014-12-11 | 2016-06-16 | 株式会社デンソー | Transmission device |
| US20160269121A1 (en) * | 2015-03-09 | 2016-09-15 | Alcatel-Lucent Usa Inc. | Modulator Biasing For Optical Transmission |
Non-Patent Citations (2)
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114024619A (en) * | 2021-10-26 | 2022-02-08 | 华中科技大学 | Back scattering communication method, device and system based on pulse interval modulation |
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Application publication date: 20181127 |