CN105471499A - Coding and decoding method for enhancing visible light signal transmission rate, mobile terminal and system - Google Patents
Coding and decoding method for enhancing visible light signal transmission rate, mobile terminal and system Download PDFInfo
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Abstract
The invention discloses a coding and decoding method for enhancing visible light signal transmission rate, a mobile terminal and a receiving end adopting the method and a system. The coding method comprises the steps that mobile terminal coding is performed: code elements in data strings are read, level jumps when one code element is read, and different digits of code elements are coded into level signals with different level duration; and light signal modulation and emission are performed: light source modulation of the coded data is performed, and the data are emitted out in the mode of visible light. The receiving end can compare all the read high and low level duration with judgment duration according to the set judgment duration in decoding so that signal decoding is realized.
Description
Technical field
The present invention relates to a kind of decoding method improving visible light signal transmission rate, the especially decoding method of light signal that sends of the LED photoflash lamp of the mobile terminal such as mobile phone, and a kind of mobile terminal, and communication system.
Background technology
The light that visible light communication is sent by modulator approach modulation visible light sources such as amplitude, frequency and phase places, LED is a kind of common visible light source, and its transmission rate is up to per second several million to tens.Visible light communication can be applied in wireless light communication, is used for carrying out transfer of data.Visible light communication, compared with microwave technology, has quite abundant frequency spectrum resource, be general microwave communication and radio communication incomparable.Meanwhile, visible light communication almost can be suitable for any communication protocol, is applicable to any environment.The signal cover of visible light communication is more easy to control, and Content of Communication is not easily stolen, and has higher fail safe.In addition, the equipment of visible light communication is convenient flexibly, and cost is very low, is applicable to extensive popularization and application.
At present, LED photoflash lamp has been an important accessory of mobile phone, and the communication carrying out visible ray with the photoflash lamp of mobile phone will bring great convenience.But do like this and there is two problems, one is because the flash speed of photoflash lamp is slow, cause transmission rate little, two is when the opening and close of control LED photoflash lamp, time delay can be there is at random, the duration of the i.e. open and close of LED, the duration of opening, pass can not accurately control, and shows certain unsteadiness.Such as, patent CN102693567 gives a kind of decoding method, and is applied in gate control system, and the method just exists the less problem of amount of information of transmission each second, and owing to requiring higher to the control precision of LED, thus also there is more unstable problem.
Summary of the invention
The object of this invention is to provide a kind of decoding method improving visible light signal transmission rate, and a kind of mobile terminal and system, improve visible light signal transmission rate, eliminate the impact that the unsteadiness when the opening and close of control LED photoflash lamp causes.
For this reason, the present invention includes a kind of coding method improving visible light signal transmission rate, comprise the steps:
Mobile terminal is encoded: read the code element in serial data, when often reading a code element, and level generation saltus step, and different digital code element is encoded to the level signal with different level duration;
Optical signal modulation and transmitting: by the Data Modulation light source through encoding, described data are launched with visible ray form.
Further, described serial data is n system, n be greater than 1 integer, often read a code element, level generation saltus step, and by level continue duration/duration scope T0 ..., Tn-1 represents the different number 0 in n system ..., n-1; And T0, in Tn-1, the absolute value of the difference of any two adjacent duration/duration scopes is greater than predetermined value to reduce or to eliminate the impact of control delay inequality for different code element identification of light source, wherein, two adjacent duration/duration scopes refer to immediate two durations/duration scope of time span.
Further, T0 ..., in Tn-1, the absolute value of the difference of any two adjacent duration/duration scopes is at least greater than 1 times of the control delay inequality of light source.
Further, before mobile terminal coding, first system conversion is carried out to read serial data.
Further, read binary data string is converted to nonbinary equivalent data string by described being converted to, comprise: in binary data string to be sent, the adjacent binary code code element composition binary data string of j is got according to sequencing, by this binary data string recompile, form the equivalent data string that he number is k; Described equivalent data string is non-binary data string, and code element species number is wherein three or more; J and k is natural number, and j is greater than k; Then, each code element in equivalent data string is converted to the different level signal of duration successively; Repeat step: the adjacent binary code code element continuing to take off according to sequencing one group of j, repeat above-mentioned steps, until the data in serial data to be sent all convert; Or, described in be converted to read non-binary data string be converted to binary data string or different non-binary data strings.
Further, with this light signal have or nothing continue duration represent each code element, that is: make the saltus step of level become with presence or absence of light signal and change; Wherein, high level is corresponding luminous, and low level correspondence is not luminous; Or high level correspondence is not luminous, low level is corresponding luminous.
Further, if the number of the code element that certain unit transmission time is long is greater than the number of the code element of unit transmission shortest time, and this unit transmission time long code element code element that to be overall transmission time the longest, exchanges the code element of code element the longest for this overall transmission time and unit transmission shortest time.
Further, in optical signal modulation step, mobile terminal also utilizes the light signal of brightness regulation to carry out luminous intensity coding at least part of data to be transmitted, is represented by the light signal of at least part of data to be transmitted with varying strength.
Further, in continuous multiple same symbol, at least one code element has light signal than its adjacent code element more high strength to distinguish described continuous multiple same symbol.
The present invention also comprises a kind of coding/decoding method improving visible light signal transmission rate, comprises the steps:
Light signal receives and conversion: receiving terminal receives the visible light signal of representative data string, light signal is converted to corresponding level signal;
Signal decoding: according to the duration of each level read, receiving terminal determines that the code element that each level is corresponding is digital;
Integrate: receiving terminal is integrated each group of signal received, obtain the information that visible light signal characterizes.
Further, signal decoding comprises:
Receiving terminal pre-sets n-1 judgement duration Td1 ..., Tdn-1, marks off n duration by described n-1 judgement duration interval, respectively n code element number of corresponding n system, n be greater than 1 integer;
According to the duration of the N number of level read, receiving terminal judges that the duration of each level fallen into separately duration is interval, thus determine that code element corresponding to the duration of each level is digital, N be greater than 0 integer.
Further, described n-ary digit is binary data string according to string, arrange in judgement duration step and a judgement duration Td is only set, in signal decoding step, the duration of the N number of level collected is compared with Td respectively, if the duration of certain level is less than Td, then this level representative 0, if the duration of certain level is greater than Td, then this level representative 1, if the duration of certain level equal Td, then this level representative 0 or 1; Or,
Described n-ary digit is binary data string according to string, arrange in judgement duration step and a judgement duration Td is only set, in signal decoding step, the duration of the N number of level collected is compared with Td respectively, if the duration of certain level is less than Td, then this level representative 1, if the duration of certain level be greater than Td, then this level representative 0, if the duration of certain level equals Td, then this level representative 0 or 1.
Further, the method arranging judgement duration Td is as follows:
Appoint and get natural number m, 1≤m≤N, calculate the mean value Ta of a maximum N/m level duration, the mean value Tb of N/m minimum level duration, wherein, so, judgement duration is Td=(Ta+Tb)/2, wherein, if N/m is aliquant, and a round numbers part.
The present invention also comprises a kind of mobile terminal, the coding method described in employing.
The present invention also comprises a kind of receiving terminal, adopts above-mentioned coding/decoding method.
The present invention also comprises a kind of optical communication system, comprises above-mentioned mobile terminal and receiving terminal.
Owing to have employed such scheme, the present invention carrys out different digital code element in representative data string with the various durations that LED opens or closes, such as data 0 and 1, low level and high level (Guan Hekai of corresponding LED) are all used for characterization data, thus substantially increase transmission rate; On the other hand, although the control precision of mobile phone LED flash lamp is not high, it controls time delay substantially within the scope of one; Although time delay is random generation, show certain probabilistic statistical characteristics.According to this stroboscopic nature of mobile phone LED flash lamp, the present invention is by arranging judgement duration at receiving terminal to the reasonable process controlling time delay and luminous duration, ensure that low and high level can not produce in an encoding process to obscure, thus make low and high level all can be used for expression information, therefore effectively can improve the transinformation of each second.
Accompanying drawing explanation
Fig. 1 is the decoding method flow chart of the visible light signal that the embodiment of the present invention one provides;
Fig. 2 is the relation schematic diagram between the signal that provides of the embodiment of the present invention one and level (light intensity).
Fig. 3 is the relation schematic diagram between the signal that provides of the embodiment of the present invention four and light intensity.
Embodiment
Code element alleged herein refers to the digital efm of each forming arbitrary carry system serial data, and the code element of such as binary data string 00111 is 0,0,1,1,1, and the code element of ternary data string 012201 is 0,1,2,2,0,1.Two kinds of numbers are comprised for binary data string: 0 and 1; Three kinds of numbers can be comprised: 0,1 and 2 for ternary data string; N kind can be comprised according to string digital: 0,1,2 for n-ary digit ... n-1.
According to embodiments of the invention, the coding method improving visible light signal transmission rate comprises the steps:
Mobile terminal is encoded: read the code element in serial data, when often reading a code element, and level generation saltus step, and different digital code element is encoded to the level signal with different level duration;
Optical signal modulation and transmitting: by the Data Modulation light source through encoding, described data are launched with visible ray form.
In a further embodiment, described serial data is n system, n be greater than 1 integer, often read a code element, level generation saltus step, and by level continue duration/duration scope T0 ..., Tn-1 represents the different number 0 in n system ..., n-1; And T0, in Tn-1, the absolute value of the difference of any two adjacent duration/duration scopes is greater than predetermined value to reduce or to eliminate the impact of control delay inequality for different code element identification of light source, and wherein, two adjacent duration/duration scopes refer to immediate two durations of time span.
T0 ..., in Tn-1, the absolute value of the difference of any two adjacent duration/duration scopes is at least greater than 1 times of the control delay inequality of light source.In coding method preferred embodiment, T0 ..., in Tn-1, the absolute value of the difference of any two adjacent duration/duration scopes is greater than 2 times of the control delay inequality of light source.
According to embodiments of the invention, the coding/decoding method improving visible light signal transmission rate comprises the steps:
Light signal receives and conversion: receiving terminal receives the visible light signal of representative data string, light signal is changed into corresponding level signal;
Signal decoding: according to the duration of the level read, receiving terminal determines that the code element that each level is corresponding is digital;
Integrate: receiving terminal is integrated each group of signal received, obtain the information that visible light signal characterizes.
In a further embodiment, above-mentioned signal decoding comprises:
Receiving terminal pre-sets n-1 judgement duration Td1 ..., Tdn-1, mark off n duration by described n-1 judgement duration interval, n code element of corresponding n system is digital respectively; N be greater than 1 integer; Judgement duration can be selected according to the statistical law of test.
Receiving terminal according to the duration of the N number of level read respectively with Td1 ..., Tdn-1 compares, and judges that the duration of each level fallen into separately duration is interval, thus determines that code element corresponding to the duration of each level is digital, N be greater than 0 whole.
Described n-ary digit is binary data string according to string, arrange in judgement duration step and a judgement duration Td is only set, in signal decoding step, the duration of the N number of level collected is compared with Td respectively, if the duration of certain level is less than Td, then this level representative 0, if the duration of certain level be greater than Td, then this level representative 1, if the duration of certain level equals Td, then this level representative 0 or 1; Or, described n-ary digit is binary data string according to string, arrange in judgement duration step and a judgement duration Td is only set, in signal decoding step, the duration of the N number of level collected is compared with Td respectively, if the duration of certain level is less than Td, then this level representative 1, if the duration of certain level is greater than Td, then this level representative 0, if the duration of certain level equal Td, then this level representative 0 or 1.
Below by way of several specific embodiment, Code And Decode method of the present invention is described further.
Embodiment one:
The present embodiment illustrates a kind of decoding method of visible light signal, can improve visible light signal transmission rate, and described method comprises:
Mobile terminal is encoded in the following manner to the N bit-binary numeral signal obtained:
When often reading a code element 0 (hereinafter referred to as 0) or code element 1 (hereinafter referred to as 1), there is a saltus step in level, and duration level being continued T0 represents 0, duration level being continued T1 represents 1, T0 < T1, or T0 > T1; By through coding signal madulation become visible light signal, the saltus step of level is become with presence or absence of light signal and changes, and by this light signal have or nothing continue duration T0, T1 represent 0 or 1.The benefit of this coding method is: represent synchronizing signal with level saltus step, represents 0 or 1 with the duration that level continues, and like this, each duration can be used for representing signal, and density of encoding increases greatly, thus can improve transmission rate.But, due to when the opening and close of control LED photoflash lamp, at random time delay can occur, i.e. the duration of the open and close of LED, the duration of opening, pass can not accurately control, show certain unsteadiness, cause and represent that signal time error may be larger with duration.
For this reason, the present embodiment proposes further improvement project, is described as follows that (light modulation can be divided into two kinds of situations, and the first is that high level is corresponding luminous, and low level correspondence is not luminous; The second is that high level correspondence is not luminous, and low level is corresponding luminous.Be described for the first situation below):
Mobile terminal (transmitting terminal): the absolute value (| T0-T1|) of the difference between setting 0 and the duration of 1 is greater than 2 times of the control delay inequality of photoflash lamp.The control delay inequality of said photoflash lamp refers to the maximum delay Δ t of photoflash lamp herein
maxwith minimum time delay Δ t
minbetween difference.Such as: send command request photoflash lamp at moment t1 luminous, but it is just luminous at t1 ' moment photoflash lamp, just there is a time delay Δ t1=t1 '-t1 therebetween, equally, send command request photoflash lamp at moment t2 to close, but just close at t2 ' moment photoflash lamp, just have a time delay Δ t2=t2 '-t2 therebetween.The maximum Δ t of all these time delays
maxwith minimum value Δ t
minbetween difference, be called the control delay inequality of photoflash lamp in the application.After difference between the present embodiment setting 0 and the duration of 1 is greater than 2 times of the control delay inequality of photoflash lamp, still can ensure that the actual duration T0 of the symbol data that the actual duration T1 of the symbol data that duration is larger is less than duration is long, namely | T0-T1|-2 (Δ t
max-Δ t
min) >0, would not to cause at transmitting terminal just the data obfuscation of two durations.Certainly, for having the binary system of any number of code element or non-two-stage system serial data, the absolute value of the difference of any two adjacent durations more preferably greater than 2 times of control delay inequality of light source, thus prevents from distinguishing different digital code element because of time delay.Two adjacent durations refer to immediate two durations of time span.
When meeting | T0-T1|>2 (Δ t
max-Δ t
min) time, larger duration may be caused long, thus reduce emission effciency.In order to average out between emission effciency and recognition correct rate, also not necessarily meet in practical application | T0-T1|>2 (Δ t
max-Δ t
min).
In practical application, the photoflash lamp time delay of every money mobile terminal is not identical, needs the test carried out repeatedly.
Receiving terminal: receiving terminal detects visible light signal, converts light signal to the signal of telecommunication by photoelectric conversion device, has the corresponding high level of light, unglazed corresponding low level.Detect the duration of low and high level, N number of level duration, then stores altogether.Then by the judgement duration Td that receiving terminal sets, the above-mentioned N number of level duration received is compared, thus distinguishes the duration representing 0 and 1 respectively.In comparison procedure, as T0 < T1, T0 < Td≤T1, the duration (t1 of N number of level that top is collected, t2,, tn, n≤N) compare with Td respectively, if tn≤Td, then these level representative data 0, if tn > Td, then these level representative data 1; As T0 > T1, T0 >=Td > T1, duration of N number of level that top is collected (t1, t2 ... tn, n≤N) compare with Td respectively, if tn≤Td, then these level representative data 1, if tn > Td, then these level representative data 0.Then combining comparing the binary digital signal obtained according to the method described above, just recovering the initial data that mobile terminal sends.
Why adjudicate duration Td in receiving terminal setting, because the duration of the open and close of LED, the duration of opening, pass can not accurately control, show certain unsteadiness, actual situation about sending cannot be known in advance, thus also just cannot pre-determine the judgement duration that transmitting terminal (mobile terminal) and receiving terminal are all consistent.As follows in the method for receiving terminal setting judgement duration Td:
Any round numbers m, 1≤m≤N, calculate maximum N/m (if aliquant, round numbers part) the mean value Ta of individual level duration, minimum N/m is (if aliquant, round numbers part) the mean value Tb of individual level duration, so judgement duration is Td=(Ta+Tb)/2.The calculating of m value larger judgement duration is more accurate.
Further describe as follows to the present embodiment below:
See Fig. 1, be the decoding method flow chart of the visible light signal that the embodiment of the present invention one provides, this coding method comprises:
S101: information of mobile terminal reads: read the information stored in the terminal, information is converted to binary digital signal.
Wherein, mobile terminal can be the mobile phone, panel computer etc. of band LED photoflash lamp.
S102: mobile terminal is encoded: when reading 0, level generation saltus step, and the duration this level being continued T0 represents 0; When reading 1, level generation saltus step, and the duration this level being continued T1 represents 1.T0 < T1, or T0 > T1.
S103: optical signal modulation and transmitting: by the LED photoflash lamp of the modulates information mobile terminal after coding, by the signal madulation visible light signal through coding.Light modulation can be divided into two kinds of situations, and the first is that high level is corresponding luminous, and low level correspondence is not luminous; The second is that high level correspondence is not luminous, and low level is corresponding luminous.Here for the first situation, and T0 < T1, above-mentioned coding method is described.
Such as, as T0 < T1, T0 is set to 2ms, and T1 is set to 30ms, and the level waveforms of data 10011010 correspondence as shown in Figure 2.
Coded message is sent with the form of visible ray.
S104: light signal receives: receiving terminal receives visible light signal, changes light signal into the signal of telecommunication.
S105: read and store the low and high level duration: receiving terminal detects the duration of low and high level, N number of level duration, then stores altogether.
S106: Lookup protocol judgement duration Td: calculate maximum N/m (if aliquant, round numbers part) the mean value Ta of individual level duration, minimum N/m is (if aliquant, round numbers part) the mean value Tb of individual level duration, wherein, 1≤m≤N, so judgement duration is Td=(Ta+Tb)/2.
S107: signal decoding: the duration of all low and high levels read and judgement duration compare by receiving terminal, duration (the t1 of N number of level that top is collected, t2,, tn, n≤N) compare with Td respectively, if tn < is Td, then these level representative data 0, if tn > Td, then these level representative data 1.
S108: receiving terminal is integrated each group of signal received, obtains the information that visible light signal characterizes.
The code encoding/decoding mode that the present embodiment provides, utilizes the switch of the LED of the mobile terminals such as mobile phone controlled, and the performance that the duration of opening and closing is controlled, proposes a kind of coded system, and the various durations opened or closed with LED carrys out representative data 0 and 1.When mobile phone obtains data, adopt coded system provided by the invention, information is encoded, then the information after coding is sent with the form of visible light signal by LED photoflash lamp.Receiving terminal receives visible light signal, by electrooptical device, changes light signal into the signal of telecommunication, detects high level and low level duration, then by judging this duration, decoding to the signal obtained, recovering initial data.This programme efficiently solves the characteristic of the LED photoflash lamp flicker instability of the mobile terminals such as mobile phone, can realize the communication between the mobile terminals such as mobile phone and visible light signal receiving terminal, can improve the transmission rate of light signal between them.
Embodiment two: (segment encoding also condenses by multi-system, and N system is just with N kind waveform)
Binary digital signal to be sent is often got triad number according to ternary recompile by the present embodiment, meets 2 to enter for 1 (code element 2 is called for short 2), as shown in table 1:
Table 1 decimal system, binary system and ternary digital correspondence table
| The decimal system | Binary system | Ternary |
| 0 | 000 | 00 |
| 1 | 001 | 01 |
| 2 | 010 | 10 |
| 3 | 011 | 02 |
| 4 | 100 | 11 |
| 5 | 101 | 12 |
| 6 | 110 | 20 |
| 7 | 111 | 21 |
Decoding method and the embodiment one of the visible light signal of the present embodiment are similar, difference is signal to be encoded two kinds of code elements 0 by binary digital signal, 1 composition becomes by three of ternary digital signal kinds of code elements 0, 1, 2 compositions, correspondingly, mobile terminal is encoded in the following manner to the ternary digital signal obtained: often read 0, 1, during 2 arbitrary code element, level generation saltus step, duration level being continued T0 represents 0, duration level being continued T1 represents 1, duration level being continued T2 represents 2, T0, T1, the value of T2 is different.By through coding signal madulation become visible light signal, the saltus step of level is become with presence or absence of light signal and changes, and by this light signal have or nothing continue duration T0, T1, T2 represent 0,1,2.Similarly, the absolute value of the difference between the respective duration of setting 0,1,2 is greater than 2 times of the control delay inequality of photoflash lamp, causes at the data obfuscation of transmitting terminal by different duration to avoid the control time delay of photoflash lamp.
It should be noted that: above-mentioned binary system and ternary corresponding relation are only the simplest example, ternary two bit code of its correspondence can be adjusted according to the occurrence probability of three bit codes in binary code string in practical application, three bit codes that such as occurrence probability is the highest are adjusted to corresponding ternary 00, three bit codes that occurrence probability is minimum are adjusted to corresponding ternary 21 or 12, to shorten total transmitting time.Such as, through the first step three sections upset in the present embodiment, in code string, 010 probability occurred is greater than 011, and send 10 time obviously short than the time of transmission 02, so the ternary code 02 and 10 of corresponding Binary Zero 10 and 011 is exchanged, to realize shortening the object of transmitting time.As above, shown in table, 010 in binary system be 02 in corresponding ternary originally, but exchanges 10 in rear corresponding ternary, and 10 in the corresponding ternary originally of 011 in binary system, but exchange 02 in rear corresponding ternary (see bolded section in table).
After coding, ternary numerical value is from 00 to 21, and be all two bit codes, corresponding binary system is all three bit codes, does not have independent one 0 and one 1.
Decoding method of the present invention is obviously not only suitable for binary system or ternary digital signal, the present embodiment can also be done following expansion again: in binary digital signal to be sent, (character in digital signal is called code element to get the individual adjacent binary code code element of j according to sequencing, in binary system, its value is 1 or 0) composition binary digital signal string, by this binary digital signal string recompile, form the equivalent data string that he number is k; Described equivalent data string is nonbinary digital signal string, and code element species number is wherein three or more; J and k is natural number, and j is greater than k; Then, each code element in equivalent data string is converted to the different level signal of duration successively; Repeat step: the adjacent binary code code element continuing to take off according to sequencing one group of j, repeat above-mentioned steps, until the data in digital signal to be sent all convert.
Such as: in previous example, be the situation of j=3, k=2, but in recompile step, also can make j=2, k=1, then described in switch process, the length of different wave needs 4 kinds.
Embodiment three: (code element long for transmitting time and the short code element of transmitting time are exchanged by upset: under particular cases)
Decoding method and the embodiment one, two of the visible light signal of the present embodiment are similar, difference is, in this example, if the number of the code element that certain unit transmission time is long is greater than the number of the code element of unit transmission shortest time, and this unit transmission time long code element code element that to be overall transmission time the longest, exchanges the code element of code element the longest for this overall transmission time and unit transmission shortest time; And adopt and exchange mark and identify.
Such as, for situation ternary in embodiment two, we can be set as follows upset strategy: if the number that the number of 1 is greater than 0, and the number that the number of 0 is greater than 2 is multiplied by the average time of transmission 2 divided by the value after the average time of transmission 1, then 0 and 1 exchange (now by secondary overturning mark position 1), now because 1 is the longest code element of overall transmission time, 1 and 0 are exchanged and more can save the transmission time by than being exchanged in 2 and 0; If the number that the number of 2 is greater than 0, and the number that the average time that the number of 2 is multiplied by transmission 2 is greater than 1 divided by the value of the average time of transmission 1, then 0 and 2 exchange (now by secondary overturning mark position 2), now because 2 is the longest code elements of overall transmission time, 2 and 0 are exchanged and more can save the transmission time by than being exchanged in 1 and 0, otherwise do not exchange (now by secondary overturning mark position 0).
Embodiment four: (adding intensity modulated on the basis of embodiment two)
Decoding method and the embodiment two of the visible light signal of the present embodiment are similar, difference is, in this example, mobile terminal also utilizes the light signal of brightness regulation to carry out luminous intensity coding to a part for data to be transmitted, the light signal of data to be transmitted with varying strength is represented, and data to be transmitted after coding is sent with light signal.Due in above-described embodiment two, the value of code element has 0,1,2 three kind, if all represented with duration, then a kind of duration of code element wherein must be had very long.In order to save the transmission time, the present embodiment is used different difference luminous intensities instead value 2 and above code element and is represented.Such as: the duration that conventional luminous intensity continues T0 represents 0; The duration that conventional luminous intensity continues T1 represents 1, but 2 do not adopt conventional luminous intensity duration T 2 to represent, but represents by the difference luminous intensity different from conventional luminous intensity, its duration can be then T1 or T0 or other.
Preferably, in continuous multiple same symbol, at least one code element has light signal than its adjacent code element more high strength to distinguish described continuous multiple code element.Such as, the level waveforms of data 100122201 correspondence as shown in Figure 3.Owing to there being continuous print three 2, if all represented by same luminous intensity, then can cause losing synchronizing signal, so represent by two difference light intensity, between each 2 and next 2, have a saltus step to represent synchronizing signal.The duration of the difference light intensity corresponding to code element 2 can be T0, also can be T1, or even other durations.In Fig. 3, in order to shorten transmitting time, improve transmission rate, the duration of 2 adopts T0.Although the duration of 0 is also T0, the light intensity of 0 is saltus step between zero light intensity and conventional light intensity, and the light intensity of 2 signals is saltus steps between two special light intensity, is enough to distinguish therebetween.
This example to be encoded transmissions by controlling the luminescence power of photoflash lamp, so just can reduce the data volume of transmission by combining power replacement duration.And the scheme of light intensity combinations can improve fail safe.Due to increasing of light intensity progression, the quantity of codified is increased greatly, a little room so just can be used to increase the fail safe of coding further.
In further embodiments, the present invention also provides a kind of mobile terminal, and this mobile terminal can adopt the embodiment of any one coding method above-mentioned.
In further embodiments, the present invention also provides a kind of receiving terminal, and this receiving terminal can adopt the embodiment of any one coding/decoding method above-mentioned.
In other embodiment, the present invention also provides a kind of optical communication system, comprise above-mentioned any one mobile terminal and any one receiving terminal.
Although the present invention describes with reference to current specific embodiment, but those of ordinary skill in the art will be appreciated that, above embodiment is only used to the present invention is described, change or the replacement of various equivalence also can be made when not departing from spirit of the present invention, therefore, as long as all will drop in the scope of claims of the application the change of above-described embodiment, modification in spirit of the present invention.
Claims (16)
1. improve a coding method for visible light signal transmission rate, it is characterized in that comprising the steps:
Mobile terminal is encoded: read the code element in serial data, when often reading a code element, and level generation saltus step, and different digital code element is encoded to the level signal with different level duration;
Optical signal modulation and transmitting: by the Data Modulation light source through encoding, described data are launched with visible ray form.
2. the coding method improving visible light signal transmission rate as claimed in claim 1, it is characterized in that: described serial data is n system, n be greater than 1 integer, often read a code element, level generation saltus step, and by duration/duration scope T0 lasting for level, Tn-1 represents the different number 0 in n system ..., n-1; And T0, in Tn-1, the absolute value of the difference of any two adjacent duration/duration scopes is greater than predetermined value to reduce or to eliminate the impact of control delay inequality for different code element identification of light source, wherein, two adjacent duration/duration scopes refer to immediate two durations/duration scope of time span.
3. the coding method improving visible light signal transmission rate as claimed in claim 2, is characterized in that: T0 ..., in Tn-1, the absolute value of the difference of any two adjacent duration/duration scopes is at least greater than 1 times of the control delay inequality of light source.
4. the coding method improving visible light signal transmission rate as claimed in claim 1, is characterized in that: before mobile terminal coding, first carry out system conversion to read serial data.
5. the coding method improving visible light signal transmission rate as claimed in claim 4, is characterized in that:
Read binary data string is converted to nonbinary equivalent data string by described being converted to, comprise: in binary data string to be sent, the adjacent binary code code element composition binary data string of j is got according to sequencing, by this binary data string recompile, form the equivalent data string that he number is k; Described equivalent data string is non-binary data string, and code element species number is wherein three or more; J and k is natural number, and j is greater than k; Then, each code element in equivalent data string is converted to the different level signal of duration successively; Repeat step: the adjacent binary code code element continuing to take off according to sequencing one group of j, repeat above-mentioned steps, until the data in serial data to be sent all convert; Or, described in be converted to read non-binary data string be converted to binary data string or different non-binary data strings.
6. the coding method of the raising visible light signal transmission rate as described in any one of claim 1 to 5, is characterized in that: with this light signal have or nothing continue duration represent each code element, that is: make the saltus step of level become with presence or absence of light signal and change; Wherein, high level is corresponding luminous, and low level correspondence is not luminous; Or high level correspondence is not luminous, low level is corresponding luminous.
7. the coding method improving visible light signal transmission rate as claimed in claim 6, it is characterized in that: if the number of the code element of certain unit transmission time length is greater than the number of the code element of unit transmission shortest time, and this unit transmission time long code element code element that to be overall transmission time the longest, exchanges the code element of code element the longest for this overall transmission time and unit transmission shortest time.
8. the coding method of the raising visible light signal transmission rate as described in any one of claim 1 to 7, it is characterized in that: in optical signal modulation step, mobile terminal also utilizes the light signal of brightness regulation to carry out luminous intensity coding at least part of data to be transmitted, is represented by the light signal of at least part of data to be transmitted with varying strength.
9. the as claimed in claim 8 coding method improving visible light signal transmission rate, is characterized in that: in continuous multiple same symbol, and at least one code element has light signal than its adjacent code element more high strength to distinguish described continuous multiple same symbol.
10. improve a coding/decoding method for visible light signal transmission rate, it is characterized in that comprising the steps:
Light signal receives and conversion: receiving terminal receives the visible light signal of representative data string, light signal is converted to corresponding level signal;
Signal decoding: according to the duration of each level read, receiving terminal determines that the code element that each level is corresponding is digital;
Integrate: receiving terminal is integrated each group of signal received, obtain the information that visible light signal characterizes.
11. coding/decoding methods improving visible light signal transmission rate as claimed in claim 10, is characterized in that: signal decoding comprises:
Receiving terminal pre-sets n-1 judgement duration Td1 ..., Tdn-1, marks off n duration by described n-1 judgement duration interval, respectively n code element number of corresponding n system, n be greater than 1 integer;
According to the duration of the N number of level read, receiving terminal judges that the duration of each level fallen into separately duration is interval, thus determine that code element corresponding to the duration of each level is digital, N be greater than 0 integer.
12. coding/decoding methods improving visible light signal transmission rate as claimed in claim 11, it is characterized in that: described n-ary digit is binary data string according to string, arrange in judgement duration step and a judgement duration Td is only set, in signal decoding step, the duration of the N number of level collected is compared with Td respectively, if the duration of certain level is less than Td, then this level representative 0, if the duration of certain level is greater than Td, then this level representative 1, if the duration of certain level equals Td, then this level representative 0 or 1; Or, described n-ary digit is binary data string according to string, arrange in judgement duration step and a judgement duration Td is only set, in signal decoding step, the duration of the N number of level collected is compared with Td respectively, if the duration of certain level is less than Td, then this level representative 1, if the duration of certain level is greater than Td, then this level representative 0, if the duration of certain level equal Td, then this level representative 0 or 1.
13. coding/decoding methods improving visible light signal transmission rate as claimed in claim 12, is characterized in that: the method arranging judgement duration Td is as follows:
Appoint and get natural number m, 1≤m≤N, calculate the mean value Ta of a maximum N/m level duration, the mean value Tb of N/m minimum level duration, wherein, so, judgement duration is Td=(Ta+Tb)/2, wherein, if N/m is aliquant, and a round numbers part.
14. 1 kinds of mobile terminals, is characterized in that adopting the coding method as described in any one of claim 1 ?9.
15. 1 kinds of receiving terminals, is characterized in that adopting the coding/decoding method as described in any one of claim 10 ?13.
16. 1 kinds of optical communication systems, is characterized in that comprising mobile terminal as claimed in claim 14, and receiving terminal as claimed in claim 15.
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