CN107231192A - The data transmission method and LED visible light communication system of double level pulse widths codings - Google Patents
The data transmission method and LED visible light communication system of double level pulse widths codings Download PDFInfo
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- H04—ELECTRIC COMMUNICATION TECHNIQUE
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- 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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Abstract
The data transmission method and LED visible light communication system encoded the invention discloses a kind of pair of level pulse widths, this method includes：Transmitting terminal is encoded using the width of high and low level, the saltus step of high and low level is used as time reference, data to be transmitted is divided into one group of n positions, according to the value of every group of data, the high level or low level pulse signal of different in width are exported, the position of saltus step occurs for the impulse level that the code value correspondence of every group of data is different；Receiving terminal recognizes the width of symbol transmission and the end of a data bit transmission by the way that data bit whether there is the saltus step of level, time reference is used as using the rising or falling along saltus step for impulse level that receives, according to next level hopping edge moment, judge the width of high level or low level pulse, the corresponding code value of data to be transmitted is recovered, data transfer is completed.The present invention can improve illumination efficiency and eliminate the baseline drift problem of signal in communication link, enhance the antijamming capability in communication link.
Description
Technical field
The present invention relates to technical field of visible light communication, and in particular to the data transfer of a kind of pair of level pulse widths coding
Method and LED visible light communication system.
Background technology
Visible light communication is LED-based radio communication new technology, and it is to be switched using LED than fluorescent lamp and incandescent lamp
Fast advantage, is communicated by the high frequency flicker of LED/light source, has light to represent 1, unglazed to represent 0, the light for sending high speed is believed
Number, then obtain information by opto-electronic conversion.Because the depth that visible light communication is illuminated is compatible, with novel energy-conserving illuminating lamp
LED's becomes increasingly popular, it is seen that Optical Communication Technology Development prospect is limitless.With traditional radio communication and other radio communication systems
System compares, it is seen that optical communication technique has that transmission power is high, is not take up radio-frequency spectrum, without electromagnetic interference, electromagnetic-radiation-free,
The advantages of saving the energy.Current visible light communication technology has become multiple national study hotspots, but most of in experiment rank
Section, although total system realized, but with a certain distance from also having from the practical stage, the property indices of system need further
Improve, implementation is also required to further perfect.
One of the problem of presently, there are is the channel coding design problem of LED visible light communication system：
Visible light communication belongs to wireless communication field, using airspace as communication channel, inevitably special by air
The influence of property, this influence is referred to as air obstacle.The air obstacle that atmospheric impurities and turbulent flow are caused makes visible light communication system
Signal to noise ratio decline, the bit error rate is improved, and communication performance greatly declines.Reduce the shadow that air obstacle is caused to visible light communication
Ring, except when communication system is built, it is necessary to select that the severe degree of air is relatively low, the place that environmental condition is relatively good,
Should also use efficient channel coding technology, should at least meet it is following some：1st, timing information will enrich, and 2, baseline drift
Want small or DC level drift amount small, 3, to have certain rule., will if line code or code stream are unsatisfactory for these requirements
Can occur problems with：1st, cause bad jittering characteristic, when timing extraction occur it is difficult, 2, the unbalanced code stream of direct current will
The DC level of signal pulse is drifted about, reduce communication system transmission quality, 3, Serial No. there is no certain rule,
Communication period can not monitor the bit error rate of circuit.Due to may be by many noise jamming, channel coding in visible light communication
As important communication approach of error correction, extensive attention has been obtained.Current visible light communication research, mostly using OOK or VPPM
Modulation system, with reference to RZ codes or NRZ codes progress intensity modulated direct to white light LEDs so as to carry out signal transmission.Such way
It is easily achieved, but frequency spectrum resource utilization rate is too low, serious waste of resources, and also the code stream direct current of signal is uneven serious, compiles
The efficiency of code is very low, causes the transmission duration entirely communicated shorter.
In addition the two of the problem of presently, there are are excessive power drain problems caused by LED junction electric capacity：
The transmission medium of visible light communication is free space, for illumination LED light emitting diodes the angle of divergence than larger,
Therefore the geometry loss of signal transmission is larger, eventually arrives at the signal far smaller than transmitting terminal of receiver.Although having reported biography
Defeated speed is more than 1Gbt/s experimental system, but realizes that the distance of high-speed transfer only has several centimetres.
When communication distance change is big, loss of signal is serious, and the bit error rate rises, and cannot reach require that for signal transmission.
Improving the distance of transmission needs to increase the power of transmission signal, that is, increases LED luminous power output, and this is accomplished by increasing LED
Light-emitting area, and the increase of area causes the junction capacity of device to increase, and frequency response characteristic declines, and maximum communication rate is again
It is restricted.It is not singly LED component, the contradiction of the power characteristic and frequency characteristic of all semiconductor devices on a device design,
Be for a long time all semiconductor device design person institute facings the problem of.Report both domestic and external can also not take into account two at present
Aspect performance, it is contemplated that can not solve in a short time, it can only improve to a certain extent.
On the basis of existing LED component, improve the response speed of system by external drive circuit, realize logical at a high speed
Letter, common scheme is to use preemphasis or equilibrium.But, because the junction capacity of illuminating LED is generally larger, in nF amount
Level, discharge and recharge of the High-speed driving signals to this electric capacity will produce larger power consumption, so as to reduce the luminous of illuminator
Efficiency.There is presently no the scheme that one can preferably solve the problems, such as excessive power drain caused by LED junction electric capacity.
The content of the invention
In view of this, in order to solve above mentioned problem of the prior art, signal of communication and LED without baseline drift are obtained
The high illumination efficiency of illumination, the data transmission method and LED visible light of a kind of pair of level pulse widths coding of present invention proposition is logical
Letter system, can both reach transmission code stream DC balance, the utilization rate of frequency band can be improved again, thus control signal transmission when
It is long, it is ensured that communication and illumination functions are all unaffected.
The present invention is solved the above problems by following technological means：
A kind of data transmission method of pair of level pulse widths coding, including：
Transmitting terminal is using double level pulse widths codings：Encoded using the width of high and low level, high and low level
Saltus step as time reference, data to be transmitted is divided into one group of n positions, according to the value of every group of data, output different in width
The position of saltus step occurs for high level or low level pulse signal, the impulse level that the code value correspondence of every group of data is different；
Receiving terminal is using double level pulse widths decodings：Symbol transmission is recognized by the way that data bit whether there is the saltus step of level
Width and the end of data bit transmission, using rising or falling along saltus step as time reference for the impulse level that receives,
According to next level hopping edge moment, judge the width of high level or low level pulse, recover data to be transmitted corresponding
Code value, completes data transfer.
Further, realize that double level pulse widths of n are encoded using n digit counters, concrete methods of realizing is：
The counting cycle of counter represents that the value of n data to be transmitted is represented with k with τ, in each cycle, coding
Device exports high level or low level, and unison counter is started counting up, when the count value of counter is identical with data to be transmitted value
When, level upset saltus step, and reset count device occur for encoder, and the high level or low level pulse of the output of such encoder are wide
Degree is equal to k τ, then corresponds to the value of data to be transmitted.
Further, realize that double level pulse widths of n are decoded using n digit counters, concrete methods of realizing is：
When each signal level saltus step, counter is started counting up, and until next time, saltus step occurs in signal level
When stop counting, count value obtains corresponding data to be transmitted value with regard to respective pulses width.
A kind of LED visible light communication system, using the data transmission method of described pair of level pulse widths coding, including：
N consolidation circuits, the data group for data to be transmitted to be divided into one group of n positions；
Pattern generator, for receiving data group waiting for transmission, converts level pulse widths encoded signal in pairs；
Analog line driver, for after amplification, the output signal of pattern generator to be driven into LED, produces optic communication letter
Number；
LED, for producing optic communication signal according to the driving of analog line driver；
Optical-electrical converter, for receiving optic communication signal；
Comparator, for recovering double level pulse widths encoded signals by judgement；
Decoder, for the double level pulse widths encoded signals recovered to be decoded, obtains n-bit data group；
Data recovery circuit, for n-bit data group to be recovered into data to be transmitted.
Compared with prior art, beneficial effects of the present invention are as follows：
1), using double level pulse widths encoding schemes, belong to the fluctuating of DC component in DC balance codes, code stream compared with
It is small so that data are not influenceed by its DC component in the transmission, it is to avoid the gradually shifting phenomenon of signal output baseline, simplify light
Receive the circuit design of terminal.The coding circuit is also very simple, and signal is without scrambler, it is possible to without Phase Lock Technique, directly
The recovered clock from signal, enormously simplify clock extracting circuit, while also improving the utilization rate of frequency band；
2), using double level pulse widths encoding schemes, the discharge and recharge number of times of LED junction electric capacity is reduced, so as to reduce
Because the power of charge and discharge electric consumption, improves illumination efficiency.
Brief description of the drawings
Technical scheme in order to illustrate the embodiments of the present invention more clearly, makes required in being described below to embodiment
Accompanying drawing is briefly described, it should be apparent that, drawings in the following description are only some embodiments of the present invention, for
For those of ordinary skill in the art, on the premise of not paying creative work, other can also be obtained according to these accompanying drawings
Accompanying drawing.
Fig. 1 is the signal waveform schematic diagram of double level pulse widths codings, wherein (a) is coding principle figure, (b) is coding
Exemplary plot；
Fig. 2 is the structural representation of LED visible light communication system；
Fig. 3 is the embodiment schematic diagram of LED visible light communication system；
Fig. 4 is the communication process schematic diagram of double level pulse widths coded systems (LED visible light communication system)；
Caused receiver baseline drift phenomenon schematic diagram when Fig. 5 connects NRZ-L codes for transmission is long；
Fig. 6 is conventional LED driving schematic diagrames；
Fig. 7 is the flow direction schematic diagram of electric current when LED drive signal is respectively high and low level.
Embodiment
In order to facilitate the understanding of the purposes, features and advantages of the present invention, below in conjunction with accompanying drawing and specifically
Embodiment technical scheme is described in detail.It is pointed out that described embodiment is only this hair
Bright a part of embodiment, rather than whole embodiments, based on the embodiment in the present invention, those of ordinary skill in the art are not having
There is the every other embodiment made and obtained under the premise of creative work, belong to the scope of protection of the invention.
Embodiment 1
The present invention provides the data transmission method of a kind of pair of level pulse widths coding, including：
Transmitting terminal is using double level pulse widths codings：Encoded using the width of high and low level, high and low level
Saltus step as time reference, data to be transmitted is divided into one group of n positions, according to the value of every group of data, output different in width
The position of saltus step occurs for high level or low level pulse signal, the impulse level that the code value correspondence of every group of data is different；
Realize that double level pulse widths of n are encoded using n digit counters, concrete methods of realizing is：
The counting cycle of counter represents that the value of n data to be transmitted is represented with k with τ, in each cycle, coding
Device exports high level or low level, and unison counter is started counting up, when the count value of counter is identical with data to be transmitted value
When, level upset saltus step, and reset count device occur for encoder, and the high level or low level pulse of the output of such encoder are wide
Degree is equal to k τ, then corresponds to the value of data to be transmitted.
Receiving terminal is using double level pulse widths decodings：Symbol transmission is recognized by the way that data bit whether there is the saltus step of level
Width and the end of data bit transmission, using rising or falling along saltus step as time reference for the impulse level that receives,
According to next level hopping edge moment, judge the width of high level or low level pulse, recover data to be transmitted corresponding
Code value, completes data transfer；
Realize that double level pulse widths of n are decoded using n digit counters, concrete methods of realizing is：
When each signal level saltus step, counter is started counting up, and until next time, saltus step occurs in signal level
When stop counting, count value obtains corresponding data to be transmitted value with regard to respective pulses width.
As shown in figure 1, Fig. 1 (a) is its coding principle, transmitting terminal is using double level pulse widths codings, in each code element
During beginning, data waiting for transmission are divided into one group by encoder per n, according to the value of every group of data, export the pulse of different in width
Signal, using level saltus step as time reference, the hopping edge of each pulse is both the end of a upper code element, is also this
The beginning of code element.If the minimum slot time of pulse is τ, then the Breadth Maximum of pulse is 2n·τ.At the time of its level saltus step with
The value correspondence of data to be transmitted group.Receiving terminal is using the saltus step of impulse level that receives as time reference, according to the electricity of signal
At the flat hopping edge moment, the value of data to be transmitted is recovered, realize the transmission of data.
Fig. 1 (b) is encoding examples, and the value of the 1st group of data to be transmitted is " 0 ", so pulse only takes up the time slot of 1 unit
Width；The value of 2nd group of data to be transmitted is " 1 ", so pulse takes the time slot width of 2 units；3rd group of data to be transmitted
It is worth for " 3 ", so pulse takes the time slot width of 4 units.This waveform appears to the pulse commonly used in analog power
The combination of width modulated and pulse frequency modulated scheme, but be essentially different：Pulse width modulation and pulse frequency are adjusted
Technology processed is to represent analog signal with data signal, is to carry out digitally coded method to analog signal level, and the present invention is
The value of binary data group is characterized with impulse level hopping edge or pulse width, belongs to a kind of multicomponent coding mode.
Embodiment 2
As shown in Fig. 2 the present invention also provides a kind of LED visible light communication system, compiled using described pair of level pulse widths
The data transmission method of code, including：
N consolidation circuits, the data group for data to be transmitted to be divided into one group of n positions；
Pattern generator, for receiving data group waiting for transmission, converts level pulse widths encoded signal in pairs；
Analog line driver, for after amplification, the output signal of pattern generator to be driven into LED, produces optic communication letter
Number；
LED, for producing optic communication signal according to the driving of analog line driver；
Optical-electrical converter, for receiving optic communication signal；
Comparator, for recovering double level pulse widths encoded signals by judgement；
Decoder, for the double level pulse widths encoded signals recovered to be decoded, obtains n-bit data group；
Data recovery circuit, for n-bit data group to be recovered into data to be transmitted.
The course of work of the LED visible light communication system of the present invention is as follows：
Data to be transmitted is divided into the data group of one group of n positions by n consolidation circuits；
Pattern generator receives data group waiting for transmission, level pulse widths encoded signal in pairs is converted, for example, to realize
The multi-pulse width coding of n, can be realized using n digit counters：If the counting cycle of counter is τ, n to be transmitted
The value of data is k, and in each cycle, encoder output high level, unison counter is started counting up, when the counting of counter
When value is identical with data to be transmitted value, there is the saltus step of low and high level, and reset count device in encoder；
The output signal of pattern generator drives LED after analog line driver amplifies, and produces optic communication signal；
In receiving terminal, optical-electrical converter receives optic communication signal, by the judgement of comparator, recovers double level pulses wide
Spend encoded signal；
The double level pulse widths encoded signals recovered are decoded through decoder, obtain n-bit data group, then by data recovery
Circuit recovers data to be transmitted, and decoder can also be realized using n digit counters：Each signal level saltus step when
Wait, counter is started counting up, stop counting when saltus step occurs in signal level next time, count value is wide with regard to respective pulses
Degree, can obtain corresponding data to be transmitted value.
The general principle of the present invention is encoded by using double level pulse widths so that the low and high level in transmission data
Duration is almost equal, DC (direct current) balances in holding circuit, to reduce the baseline drift phenomenon of receiver appearance.Reduce
The transition times of LED driving voltage, reduction is because excessive power drain caused by LED junction electric capacity.Use variable length code simultaneously
First width, shortens low duration as far as possible, improves the dutycycle of signal, on the premise of ensureing that brightness of illumination is constant,
Reduce peak point current.
The major defect of conventional symbol transmission is that receiving terminal does not have clock, the number also received without clock with regard to None- identified
According to the beginning and end and the width of data bit of position；And double level pulse widths codings solve the problem of not having clock.Connect
Receiving end can whether there is the saltus step of level to recognize the width of symbol transmission and the end of a data bit transmission by data bit；Connect
Receiving end using receive level saltus step at the time of as time reference, the position of saltus step occurs according to level next time, recovers
Corresponding code value, completes data transfer.
As shown in Figure 3, it is preferable that LED visible light communication system transmitting terminal mainly includes the n positions being made up of FPGA and merges electricity
Road and pattern generator, analog line driver and LED.Receiving terminal mainly includes optical-electrical converter, the solution that comparator and FPGA are constituted
Code device and data recovery circuit.N consolidation circuits and pattern generator receive data to be transmitted, are converted to double level pulse widths
Encoded signal, after this signal amplifies through analog line driver, drives LED, produces optic communication signal.In receiving terminal, opto-electronic conversion
Device receives optic communication signal, by the examination of comparator, recovers double level pulse widths encoded signals, eventually passes FPGA structures
Into decoder decoding, recover signal to be transmitted.
Above-mentioned FPGA is moved using the EP2C5 chips of the series of altera corp cyclone- II, logic unit 4068 on piece
State memory total bit number 119808bit, embedded 18x18 multipliers 13, phaselocked loop 2 on piece.
Above-mentioned analog line driver use mimi-circuit companies ZHL-6A amplifiers, passband 0.0025-500MHz,
Gain 25dB, peak power output 22dBm.
Above-mentioned LED uses the LE_CW_E2B light emitting diodes of OSRAM companies, rated current 700mA, luminous flux 240-
610lm。
Above-mentioned optical-electrical converter uses 1601 optical-electrical converters of new port companies, its spectral response range 320-
1000nm, bandwidth 1GHz, rise time 400ps, equivalent input noise power 31pW, conversion gain 360/W.
Above-mentioned comparator uses the max961 comparators of Maxim, and its propagation delay 4.5ns, supply voltage 3-5V are defeated
Go out level compatibility TTL and CMOS standards.
Communication process is as shown in Figure 4：Data to be transmitted is divided into the data group of one group of n positions by n consolidation circuits.Code
Type generator receives data group waiting for transmission, converts level pulse widths encoded signal in pairs.For example, to realize double electricity of n
Pulse-width is encoded, and can be realized using n digit counters：If the counting cycle of counter is τ, n data to be transmitted
It is worth for k, in each cycle, encoder output high level (or low level), unison counter is started counting up, and works as counter
Count value it is identical with data to be transmitted value when, level saltus step, and reset count device occur for encoder.So output of encoder
Pulse width is equal to k τ, then corresponds to the value of data to be transmitted.Encoder occurs after level saltus step, and next code is carried out immediately
The transmission of member.The output signal of pattern generator drives LED after analog line driver amplifies, and produces optic communication signal.
In receiving terminal, optical-electrical converter receives optic communication signal, by the judgement of comparator, recovers double level pulses wide
Encoded signal is spent, decoder decoding is eventually passed, obtains n-bit data group, then data to be transmitted is recovered by data recovery circuit.
Decoder can also be realized using n digit counters：In each signal hopping edge, counter is started counting up, signal it is next
Level hopping edge stops counting, and count value can obtain corresponding data to be transmitted value with regard to respective pulses width.
According to the principle of such scheme, the baseline that this scheme runs into LED visible light communication system is analyzed respectively now
Drifting problem and in power consumption caused by LED junction electric capacity and the characteristic in terms of brightness of illumination：
1st, the baseline drift problem run into LED visible light communication system
Baseline drift be also referred to as baseline floating, be due to data signal by AC coupled network when produce.This be because
It is different from the situation of cable transmission for optical channel, there can not possibly be negative light in optic communication, therefore can not be as cable using bipolar
The pulse of property, and unipolar pulse can only be used.In digital optical communication system, correspondence " 1 " is luminous, and " 0 " is not light,
Necessarily containing certain flip-flop in unipolar digital code stream, and what AC coupled network can not be included by code stream
DC component, when rectangular pulse is added to AC coupled network, output pulse will appear from the hangover of opposite polarity, the width of this hangover
Degree and duration are by depending on the low frequency characteristic of AC coupled network.Low-frequency cut-off frequency is lower, and tail is longer.Pulse sequence
When row are by AC coupled network, the hangover of each pulse will be overlapped mutually, and be thereby resulted in " baseline floating ", be worked as receiver
Decision level it is constant when, this floating will influence the ability of the presence or absence of receiver decision pulse.
Digital Optical Terminal for optical transmission system has two kinds of working methods：It is synchronous and asynchronous.Both different operating sides
No matter the optical transmitter and receiver of formula is constituted from the structure, design philosophy, circuit of transmission signal, or has very big on regeneration decision method
Difference, baseline drift Producing reason and its influence also different.For synchronous mode optical transmitter and receiver, what it was transmitted is continuous numeral
Sequence, baseline floats, and the reason for occurring is uneven mainly due to " 1 " and " 0 " appearance in digital code stream, and appearance is prolonged
When connecting " 1 " or even " 0 ", the amplitude of flip-flop is caused to change, when flip-flop amplitude of variation is larger, it is possible to occur
Error code.
Caused receiver baseline drift phenomenon schematic diagram when as shown in Fig. 5 transmitting long even NRZ-L codes.Can be with by figure
Find out, after AC coupled, baseline can gradually sink, if now decision threshold immobilizes, a part of " 1 " code will be made
It is mistaken for " 0 " code.In this case, only by the method for increase signal amplitude to overcome error code, but so most I is made
The average light power received becomes big, and the sensitivity to receiver causes certain loss.
Light pulse as seen from the figure can only take unipolarity, therefore light pulse contains DC component, but AC network
The DC component that can not be contained by stream packet, so the hangover of reversed polarity occurs when rectangular pulse is by AC coupled network,
And the hangover of pulse train mutually overlaps and will result in baseline drift, and for the given decision threshold level of fixation
Speech, drift will influence interpretation error code occur, as shown in Figure 5.
It is desirable in the case of wire link, expect to be used without DC and a small amount of low-frequency content code, to permit
Perhaps driver and acceptor circuit, which isolate coding in other words with the DC (direct current) of transmission line, can realize that DC is balanced, so as to reduce line
Distorted signals on road.DC balance, refers to that in one group of data 0 and 1 number is equal, then this group of data are DC balances
's.When using capacitance, electric current flows into the terminating network of receiver only when state switches.The LED visible light of the present invention
Communication system, the variable length code element width coding encoded simultaneously using high and low level, when considering the dutycycle of signal, if most
Small low level width is tL, the slot time of trailing edge difference code value is tcThen, for n m primitive encodings, the height of each code element
The mean breadth of level isAnd the low level mean breadth of each code element is alsoIt is possible thereby to see
Go out that the low and high level duration transmitted in data is almost equal, so can be balanced with the DC (direct current) in holding circuit, to carry
High baseline, therefore be not in even 0 or even 1 data occurred error code, lost because of AC coupled
Several phenomenon, so as to eliminate the generation of the baseline drift phenomenon in communication link.
2nd, energy expenditure caused by LED junction electric capacity
It is conventional LED driving schematic diagrames as shown in Fig. 6 (a), LED is driven usually using the driver of a high speed.
But, because the junction capacity of illuminating LED is generally larger, in nF magnitude, discharge and recharge of the High-speed driving signals to this electric capacity
Larger power attenuation will be produced, so as to reduce the luminous efficiency of illuminator.Power consumption caused by junction capacity discharge and recharge can
To be analyzed according to Fig. 6.Fig. 6 (b) is the driving schematic diagram after being replaced it with LED equivalent circuit, and that wherein in dotted line frame is LED
Equivalent circuit diagram.Because mainly the influence of research LED junction electric capacity, ignores the factors such as LED series resistance, LED etc.
Imitate for a desired illumination diode D it is in parallel with LED junction electric capacity CLED.
When LED drive signal is respectively high and low level, the flow direction of electric current is as shown in Figure 6.Because electric capacity fills
What electric discharge only occurred in signal rises or falls edge, so the situation to signal rising edge and trailing edge is divided separately below
Analysis：
(1), during signal rising edge, circuit energy caused by LED junction electric capacity is consumed
Fig. 7 (a) is sense of current when input is high level, now internal drive switch S closures, and power supply VH is by driving
Dynamic device internal resistance RO powers to ideal LED and it is lighted, while the junction capacity to LED charges.
Power supply is not involved in lighting to the energy of LED junction electric capacity charging consumption, is the energy expenditure of circuit.Because electric capacity does not disappear
Power consumption, so actual power is all consumed on drive circuit, i.e., in the internal resistance of drive circuit.Drive signal rising edge saltus step
Energy expenditure caused by the discharge and recharge of junction capacity can be calculated with formula (1)
In formula, iCTo flow through the electric current of LED junction electric capacity, vRoFor the voltage in driver internal resistance, VHFor the high electricity of drive signal
Flat voltage, vLEDFor the voltage (being equal to the voltage on LED junction electric capacity) on LED, trFor signal elevating time.
It is equal to for the electric current for flowing through LED junction electric capacity
Because when signal keeps high level or low level, LED voltage keeps constant, and its junction capacity does not have discharge and recharge,
LED junction resistance and the internal resistance of driver constitute simple bleeder circuit, so having
R in formulaLEDFor LED junction resistance, ROFor the internal resistance of driver.Because LED internal resistance is interior much larger than driver
Resistance, so before rising edge, the voltage on LED is approximately equal to low level VL, the voltage after rising edge is approximately equal to VH, by formula (2)
(3) substitute into formula (1) with (4) and can obtain
V in formulamFor the difference of low and high level.From formula (5), during signal rising edge, circuit energy caused by junction capacity
Consumption is directly proportional to the size of junction capacity, to square being directly proportional for the peak-to-peak value of drive signal.
(2) during signal trailing edge, circuit energy caused by LED junction electric capacity is consumed
Fig. 7 (b) is the sense of current of each several part when input voltage is low level.Now internal drive switch S is closed
Close, the electric charge that LED junction electric capacity is accumulated in high level is discharged by the internal resistance of driver, and is discharged simultaneously by preferable LED, is put
Electric current is gradually reduced, and LED gradually extinguishes.So having
The energy for flowing through the internal resistance of driver is useless, so circuit energy consumption is caused by junction capacity
I in formulaDTo flow through the electric current of desired illumination diode, the equation that preferable LED positive C-V characteristic is followed is
In formula, I0For LED reverse saturation current, q is electronic charge, vDFor LED both end voltages, n is the material with LED
The relevant constant of material, k is Boltzmann constant, and T is absolute temperature.
Formula (6) and formula (8) are substituted into formula (7), when can obtain signal trailing edge, energy caused by LED junction capacity disappears
Consume and be
Section 1 is the energy stored on LED junction electric capacity in formula, and Section 2 is the energy of LED consumption during trailing edge,
Although this portion of energy does not contribute signal of communication, it is used to light.Because LED internal resistance is interior much larger than driver
Resistance, so during signal trailing edge, the energy of driver internal resistance consumption is much larger than the energy that LED is consumed, energy caused by LED junction electric capacity
Amount dissipation is approximately equal to
(3) during signal saltus step, circuit power caused by LED junction electric capacity is consumed
Circuit power consumption is equal in the unit interval energy expenditure of saltus step every time caused by LED junction electric capacity.Therefore, to every
The probability factor of individual cycle saltus step is α, and signal frequency is f drive signal, according to formula (5) and (10), the discharge and recharge of junction capacity
Caused power consumption is
By taking common power 1W LED as an example, its typical junction capacity 1nF, if driving voltage switching frequency 100MHz, modulation
Voltage 3V, using (to unipolarity nonreturn to zero code α=0.5, other pattern α can be much higher), its power consumption during unipolarity nonreturn to zero code
150mW is reached, this will cause the very big reduction of luminous efficiency.If frequency is further lifted, or junction capacity increase (big work(
Rate LED situation), this problem will be more serious.
(4) method of circuit power consumption caused by reduction LED junction electric capacity
According to formula (11), to reduce circuit power caused by LED junction electric capacity and consume, can be by reducing drive signal saltus step
Probability, reduce clock frequency, reduce LED junction electric capacity, reduction drive signal amplitude etc. method is realized.Because once LED is selected,
Its junction capacity size is just determined substantially, in order to obtain sufficiently high signal to noise ratio, and drive signal amplitude also must be sufficiently high, so
Most viable method is exactly the coding or modulation system by improving communication system, reduces the probability of drive signal saltus step, and
Reduce clock frequency.
The present invention using double level pulse widths encoding schemes can effectively reduce drive signal saltus step probability and when
Clock frequency：Exemplified by using n m primitive encodings, system transmitting terminal is using the rising edge (or trailing edge) of driving pulse as fixed
When refer to, according to the data of required transmission, using m primitive encodings, the position of the different level saltus steps of each code value correspondence drives arteries and veins
Rush after level generation saltus step, risen or (decline) with the most fast possible speed of system immediately, carry out the biography of next code element
It is defeated.
It can be seen that in a symbol time, signal saltus step once, transmits n bits, each of which cycle
The probability factor of saltus step is α=1, and the average frequency of its signal isTherefore power consumption caused by its junction capacity discharge and recharge is
Therefore power consumption caused by LED junction electric capacity compares basic unipolarity nonreturn to zero code signal, has been reduced to original
'sWhen n is sufficiently large, it can greatly reduce excessive power drain problem caused by LED junction electric capacity.
The present invention can improve its illumination efficiency and eliminate the baseline drift problem of signal in communication link, utilize signal
The width of high and low level is encoded, and using the encoding scheme of multicomponent coding, reduces the discharge and recharge number of times of LED junction electric capacity,
So as to reduce the power because charge and discharge electric consumption, LED illumination efficiency is improved；The width of high and low level is carried out simultaneously
Coding so that the low and high level duration in transmission data is almost equal, and the DC (direct current) of signal can be kept to balance, and eliminates
Antijamming capability in the baseline drift problem of signal in visible light communication link, enhancing communication link, improves band utilization
Rate.
Embodiment described above only expresses the several embodiments of the present invention, and it describes more specific and detailed, but simultaneously
Therefore the limitation to the scope of the claims of the present invention can not be interpreted as.It should be pointed out that for one of ordinary skill in the art
For, without departing from the inventive concept of the premise, various modifications and improvements can be made, these belong to the guarantor of the present invention
Protect scope.Therefore, the protection domain of patent of the present invention should be determined by the appended claims.
Claims (4)
1. the data transmission method of a kind of pair of level pulse widths coding, it is characterised in that including：
Transmitting terminal is using double level pulse widths codings：Encoded using the width of high and low level, the jump of high and low level
Become as time reference, data to be transmitted is divided into one group of n positions, according to the value of every group of data, the height electricity of output different in width
The position of saltus step occurs for flat or low level pulse signal, the impulse level that the code value correspondence of every group of data is different；
Receiving terminal is using double level pulse widths decodings：The width of symbol transmission is recognized by the way that data bit whether there is the saltus step of level
With the end of data bit transmission, using rising or falling along saltus step as time reference for the impulse level that receives, according to
At next level hopping edge moment, judge the width of high level or low level pulse, recover the corresponding code value of data to be transmitted,
Complete data transfer.
2. the data transmission method of according to claim 1 pair of level pulse widths coding, it is characterised in that use n
Counter realizes that double level pulse widths of n are encoded, and concrete methods of realizing is：
The counting cycle of counter represents that the value of n data to be transmitted is represented with k with τ, and in each cycle, encoder is defeated
Go out high level or low level, unison counter is started counting up, when the count value of counter is identical with data to be transmitted value, compile
Level upset saltus step, and reset count device, high level or low level pulse width of the output of such encoder etc. occur for code device
In k τ, the value of data to be transmitted is then corresponded to.
3. the data transmission method of according to claim 1 pair of level pulse widths coding, it is characterised in that use n
Counter realizes that double level pulse widths of n are decoded, and concrete methods of realizing is：
When each signal level saltus step, counter is started counting up, when saltus step occurs in signal level next time
Stop counting, count value obtains corresponding data to be transmitted value with regard to respective pulses width.
4. a kind of LED visible light communication system, it is characterised in that wide using any described double level pulses of claim 1-3
The data transmission method of coding is spent, including：
N consolidation circuits, the data group for data to be transmitted to be divided into one group of n positions；
Pattern generator, for receiving data group waiting for transmission, converts level pulse widths encoded signal in pairs；
Analog line driver, for after amplification, the output signal of pattern generator to be driven into LED, produces optic communication signal；
LED, for producing optic communication signal according to the driving of analog line driver；
Optical-electrical converter, for receiving optic communication signal；
Comparator, for recovering double level pulse widths encoded signals by judgement；
Decoder, for the double level pulse widths encoded signals recovered to be decoded, obtains n-bit data group；
Data recovery circuit, for n-bit data group to be recovered into data to be transmitted.
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Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107782438A (en) * | 2017-11-28 | 2018-03-09 | 广西师范大学 | Optical fiber raster vibration measuring system based on pulse code and edge filter demodulation method |
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103546213A (en) * | 2013-10-16 | 2014-01-29 | 深圳市宏电技术股份有限公司 | Optical communication transmission method and system |
| CN104868951A (en) * | 2015-01-20 | 2015-08-26 | 深圳市裕富照明有限公司 | LED illumination-based visible light communication transmission method and system |
| CN105471499A (en) * | 2014-09-05 | 2016-04-06 | 深圳光启智能光子技术有限公司 | Coding and decoding method for enhancing visible light signal transmission rate, mobile terminal and system |
| CN105960045A (en) * | 2016-04-28 | 2016-09-21 | 华南师范大学 | Realization method and device of communication illumination sharing system based on LED high illumination efficiency |
-
2017
- 2017-02-28 CN CN201710111875.2A patent/CN107231192A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103546213A (en) * | 2013-10-16 | 2014-01-29 | 深圳市宏电技术股份有限公司 | Optical communication transmission method and system |
| CN105471499A (en) * | 2014-09-05 | 2016-04-06 | 深圳光启智能光子技术有限公司 | Coding and decoding method for enhancing visible light signal transmission rate, mobile terminal and system |
| CN104868951A (en) * | 2015-01-20 | 2015-08-26 | 深圳市裕富照明有限公司 | LED illumination-based visible light communication transmission method and system |
| CN105960045A (en) * | 2016-04-28 | 2016-09-21 | 华南师范大学 | Realization method and device of communication illumination sharing system based on LED high illumination efficiency |
Cited By (19)
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| CN110874062A (en) * | 2018-09-04 | 2020-03-10 | 苏州迪芬德物联网科技有限公司 | Intelligent home system based on WIFI |
| CN110278057B (en) * | 2019-06-28 | 2021-08-24 | 中国矿业大学 | Variable code length RLL coding and decoding method based on visible light communication |
| CN110278057A (en) * | 2019-06-28 | 2019-09-24 | 中国矿业大学 | A kind of long RLL coding and decoding method of time-varying code based on visible light communication |
| CN111405286A (en) * | 2020-03-30 | 2020-07-10 | 辽宁航空智能制造研究院有限公司 | Self-adaptive coding and decoding double-line information transmission method and device |
| CN111405286B (en) * | 2020-03-30 | 2023-11-03 | 沈阳航空产业技术研究院有限公司 | Self-adaptive coding and decoding double-line information transmission method and device |
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| US12075845B2 (en) | 2020-06-18 | 2024-09-03 | Shenzhen Smoore Technology Limited | Aerosol atomization device, test device, control method therefor, and control apparatus thereof |
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