CN103414676B - A kind of self adaptation self synchronous TCM-MPPM coded modulation demodulation communication means - Google Patents
A kind of self adaptation self synchronous TCM-MPPM coded modulation demodulation communication means Download PDFInfo
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Abstract
The invention discloses a kind of self adaptation self synchronous TCM MPPM coded modulation demodulation communication means and system, described method includes: use Trellis-coded modulation and multi-system pulse position modulation composition TCM MPPM to encode combined modulation；Information motor synchronizing collection and adaptive demodulation and decoding is carried out at receiving terminal.The present invention can make system improve error performance, automatically adjusts slot offset, while improving communication efficiency, it is ensured that the reliability of system.
Description
Technical field
The present invention relates to the communications field, be specifically related to a kind of self adaptation self synchronous TCM-MPPM coded modulation demodulation communication means.
Background technology
In the communication system using multi-system pulse position modulation (MPPM) scheme at present, there is problems in that
(1) simple MPPM modulation does not possess error correcting capability, need to add chnnel coding, while making communication system have error correcting capability, take into account effectiveness and the real-time of system again, and therefore the complexity of coding and decoding can not be the highest.
(2) asynchronous due to the crystal oscillator of transmitting-receiving two-end, can there is the slot offset of information along with the growth of call duration time in the signal that receiving terminal receives, causes receiving terminal decoding error.In order to avoid slot offset causes decoding error, original solution to be to increase the insertion frequency of synchronization frame.Although success communication so can be realized, but greatly limit the communication efficiency of communication system.
Summary of the invention
For the deficiencies in the prior art, the present invention provides a kind of self adaptation self synchronous TCM-MPPM coded modulation demodulation communication plan, this programme is used, it is possible to obtain following effect in wireless light communication or super broad band radio communication system etc. use the application scenario of MPPM modulation-demo-demodulation method:
(1) make system while improving error performance, there is high efficiency of transmission；
(2) demodulation joint decoding mode based on maximum likelihood is used at receiving terminal, it is not necessary to carry out the setting of threshold value thresholding, simplified decoding algorithm, make receiving terminal that the time-varying of channel is had higher robustness simultaneously；
(3) during the demodulation joint decoding of TCM-MPPM, add Self-synchronous algorithm, make system can automatically adjust the slot offset occurred due to the growth of call duration time, thus while improving communication efficiency, it is ensured that the reliability of system.
Technical scheme:
A kind of self adaptation self synchronous TCM-MPPM coded modulation demodulation communication means, including:
Grid coding combined modulation based on multi-system pulse position modulation；
Information motor synchronizing collection and adaptive demodulation and decoding is carried out at receiving terminal.
Described grid coding combined modulation based on multi-system pulse position modulation, is called for short TCM-MPPM coded modulation, and its step includes:
(1) data to be sent of regular length are pressed encoder for convolution codes input length packet, during often group is sequentially sent to encoder for convolution codes, obtains organizing more and export sequences of code bits accordingly；
(2) calculate and will often organize after sequences of code bits is mapped to PPM signal, the position that PPM signal high level occurs；
(3) according to frame format, frame synchronization head section is combined with frame information section, and insert preparation transmitting in caching to be sent；
(4) contents projection sent in caching is gone out by TCM-MPPM transmitting terminal, completes the primary emission of a communication frame.
Described information motor synchronizing gatherer process is as follows: first receiving terminal carries out synchronous head detection, and after all information synchronized after head section are all gathered and record, correcting program by slot offset and correct the skew of time slot, the TCM-MPPM modulated signal making TCM-MPPM modulated signal and the transmitting received is Tong Bu.
Described synchronous head detecting step includes:
(1) two data memory windows, respectively one the big window being used for depositing sampled point and the wicket for maximum in finding big window that can slide in big window are set up；
(2) value in the two window is all initialized as 0；
(3) receiving terminal often reads an analog-digital conversion result, just this result is stored in big window, and this sampled value and before continuous sampled value the most several times are stored in wicket；
(4) calculate this sub-value sum in wicket, and compare with last and value, if this and value are more than or equal to last and be worth, then current wicket is recorded apart from the side-play amount of big Window Start point；If this and value are less than last and value, then continue to retain the side-play amount of last registration；
(5) step (3) is repeated, during until big window collection is full, can find in this big window and that position of the continuous maximum of sampled result the most several times, the location determination that this maximum is occurred is the position that light pulse occurs, namely have found a light pulse synchronizing head section；
(6) repeat step (2), find the position of light pulse in next big window, then make comparisons with the position of light pulse in previous group sampled value, if the position that in these two groups, light pulse occurs is identical, then shows and have found a light pulse synchronizing head section；If the position that in these two groups, light pulse occurs is different, then it is assumed that in previous group, light pulse position is for once to judge by accident, light pulse in this group is designated as synchronizing first light pulse of head section；
(7) repeating step (2), until detecting and the identical light pulse of synchronization head section defined in frame format, completing the detection of synchronous head.
Described slot offset is corrected program step and is included:
(1) position of sampled point to TCM-MPPM modulated signal is calculated according to the form of information frame；
(2) position that in judgement information frame, in sampled point, light pulse occurs；
(3) position that the position of contrast actual samples light pulse out occurs with light pulse in TCM-MPPM standard signal, it is judged that whether the light pulse of frame information section offsets；
(4) if not offseting, then directly the sampled result of this information frame will be stored；If there occurs skew, being then adjusted it according to side-play amount, the result after adjusting stores；
(5) repeat step (1), until whole frame information section process terminates, and will store in order without the information frame of skew.
Described adaptive demodulation includes with decoding procedure:
(1) branch metric calculated and compare, selecting minimum branch metric to eliminate parallel transfer path；
(2) calculate and compare path metric, select and store path measure maximum path as surviving path, store corresponding buffer status value simultaneously；Wherein, path metric is equal to reach each branches of states and measures sum；
(3) repeat step (1), continue to calculate the branch metric of next group signal, update path metric and surviving paths matrix and retain mapping matrix；
(4) after arriving certain decoding depth, select one that in surviving path, path metric is maximum to carry out traceback decoding algorithm, traceback decoding result is stored in decoding result cache device.
Accompanying drawing explanation
Fig. 1 is that self adaptation self synchronous TCM-MPPM coded modulation demodulates communication system block diagram.
Fig. 2 is (4,3,2) structure of convolution code encoder figure.
Fig. 3 is (4,3,2) encoder for convolution codes grid chart (wherein solid line is input 0, and dotted line is input 1).
Fig. 4 describes TCM-16PPM signal collection segmentation situation.
Fig. 5 describes TCM-MPPM communication frame format.
Fig. 6 is that TCM-MPPM modulated signal launches flow chart.
Fig. 7 is the synchronous head testing process block diagram in the present invention.
Fig. 8 is the correction FB(flow block) of the slot offset in the present invention.
Fig. 9 is the hardware platform example block diagram of the present invention.
Detailed description of the invention
As a example by a kind of self adaptation self synchronous TCM-16PPM coded modulation demodulation communication plan, the present invention is elaborated below.
The system block diagram of whole self adaptation self synchronous TCM-MPPM coded modulation demodulation communication system is as shown in Figure 1.
First, the serial ports using PC sends the information of one group of regular length to TCM-MPPM transmitting terminal, TCM-MPPM transmitting terminal can carry out TCM-MPPM coded modulation to information after receiving this group information, and use the signal after coded modulation to drive laser instrument to control drive circuit for laser, thus realize the transmitting of signal.
The logic step of TCM-MPPM transmitting terminal coded modulation and transmission is as follows:
1. the data to be sent of regular length are pressed encoder for convolution codes input length packet, and sends in encoder for convolution codes a group by a group, obtain organizing more and export sequences of code bits accordingly；
Due to TCM coding modulation technique be the redundancy utilizing modulated signal collection to obtain error correcting capability, the most in this example, devise (4,3, a 2) encoder for convolution codes, the most as shown in Figure 2.Its grid chart is as shown in Figure 3；
First the information of 21 bytes (21*8bit) to be sent press bit decompose, and every 3 bits are as one group, 56 groups altogether；
Next 3 bits of each group are sent in (4,3, the 2) encoder for convolution codes shown in Fig. 2 the most in order, obtain the sequences of code bits of 56 groups of 4bit of correspondence.
2. calculate and will often organize after sequences of code bits is mapped to PPM signal, the position that PPM signal high level occurs；
In this example, between every 4bit information and the TCM-16PPM signal after coding, mapping relations are as shown in Figure 4.Owing to the 4bit information after coding can represent some numerical value in metric 0 to 15, and some numerical value in these 16 values can represent with the high level on some time slot in 16PPM modulated signal, this completes from TCM diversity signal to the conversion of 16PPM modulated signal, i.e. by (4,3,2) value of the sequences of code bits of these 56 groups of 4bit of encoder for convolution codes output, it is possible to directly determine the position of the high level of 56 16PPM modulated signals of correspondence.
3. according to frame format, frame synchronization head section is combined with frame information section, and insert preparation transmitting in caching to be sent；
In this example, the time span of each time slot that signal is launched in definition is 10us.Its communication frame format is as shown in Figure 5；
In example, a communication frame is made up of frame synchronization head section and frame information section two parts.Frame synchronization head section is made up of three protection sections and three light pulses, and wherein the protection section persistent period is 32 slot times, and light pulses duration is 1 slot time.Frame information section is made up of 56 information frames, and each information frame comprises a protection section and message segment, and wherein protection section continues the time when being 32 time slots, and message segment is a TCM-16PPM modulated signal；
First transmitting terminal inserts protection section between these 56 TCM-16PPM modulated signals, forms frame information section, adds frame synchronization head section afterwards, material is thus formed a communication frame before frame information section.Communication frame is pressed bit write subsequently send in caching, be ready for sending.
4. the contents projection sent in caching is gone out by TCM-MPPM transmitting terminal, completes the primary emission of a communication frame.The information frame of TCM-MPPM transmitting terminal launches flow process as shown in Figure 6.
Transmitting terminal in this example, owing to the time span of a time slot is 10us, sets the timer interruption of a 10us the most here, when entering interruption, should send high level or low level in judging ensuing 10us according to flow process shown in Fig. 6 every time.Detailed process is as follows:
First determine whether to synchronize head section whether battery has fired, if synchronizing head section not yet battery has fired, then enter synchronous head and launch.Now judge to synchronize the protection section whether battery has fired of head section, if the protection section synchronizing head section does not has battery has fired, then should launch low level, and the protection section count value synchronizing head section is subtracted one；If synchronizing the protection section battery has fired of head section, then should launch high level, and synchronization head section photo-impulses counting value is subtracted one.When entering interruption, continue to synchronize the emission process of head section next time, until synchronizing the whole battery has fired of head section, now can produce a prompting and indicating, making enter the transmitting initially entering message segment when interrupting next time.When entering the transmitting of message segment, first have to judge whether to have loaded the high level position of present frame.If there is no loading position information, then loading position information.Message segment to be judged the most battery has fired; if there is no battery has fired, then detect the protection section whether battery has fired of the current information frame of message segment, if the protection section of current information frame does not has battery has fired; then launching low level, the protection section count value of current information frame subtracts one.After the protection section battery has fired of current information frame, begin to launch the message segment of current information frame.When launching information frame, first having to judge whether to arrive the position sending high level, if arriving this position, then launching high level；If not arriving this position, then launch low level.When, after the high level battery has fired of information frame, needing to judge this information frame the most battery has fired, if battery has fired, then information frame count value to be sent is subtracted one, the protection section count value of reset information section；If there is no battery has fired, then continue to launch this information frame.So go on, until full detail frame is sent, just completes the primary emission of a communication frame, and to be launched numerical value is subtracted one.Now need to judge whether that needs re-emit, if desired re-emit, then reset synchronous head count value, synchronize the correlometer numerical value such as head section protection section count value, prepare transmitting next time；If need not re-emit, then the information demonstrating the need for launching the most all is sent, and now produces a flag bit, makes to enter next time when interrupting and does not launch any information.This completes the whole of a communication frame and launch work.
Above-mentioned low and high level signal controls the light on and off of laser instrument by drive circuit for laser, thus realizes the transmitting of light pulse, thus passes the information on away.
The photoelectric switching circuit of system reception part converts optical signals to analog electrical signal, sends into analog to digital conversion circuit and becomes digital signal, and TCM-MPPM receiving terminal carries out motor synchronizing collection and the demodulation coding of information successively.Finally, decoding result is sent on PC display by serial ports.
Next correlation technique and the logic step of TCM-MPPM receiving terminal are introduced.
By the data after photoelectric switching circuit and analog to digital conversion circuit, processor can be admitted to and carry out the motor synchronizing collection of information and the adaptive demodulation of information and decoding.
In order to make receiving terminal can accurately sample the light pulse that transmitting terminal sends, the every 2us of receiving terminal in this example is to reading analog to digital conversion circuit transformation result to photoelectric switching circuit.The each time slot of TCM-16PPM launched due to transmitting terminal is 10us, and the receiving terminal sampling interval is 2us, and therefore each time slot acquires 5 sampling points.
Receiving terminal first has to detect synchronous head.After synchronous head detection, thus the communication frame structure of example is it was determined that protection section that ensuing information is 56 groups of TCM-16PPM modulated signals and each of which.Owing to the system clock of transmitting terminal Yu receiving terminal certainly exists certain error (such as 10ns), growth along with call duration time, the accumulation of this error will reach very big (such as 2us), now will necessarily cause the skew of communication system time slot, cause the asynchronous of receiving terminal and transmitting terminal information, appearance cannot decode or the phenomenon such as decoding error, so that communication failure.Therefore after needing all information after synchronizing head section all to gather and record, being corrected the skew of time slot by communication time slot adjustment programme, the TCM-16PPM modulated signal making TCM-16PPM modulated signal and the transmitting received is Tong Bu.
The detection of synchronous head, the collection of signal and the correction procedure of slot offset are together defined as the motor synchronizing gatherer process of information.Synchronous head testing process as it is shown in fig. 7, the correction flow process of slot offset as shown in Figure 8.
The logic step that TCM-MPPM receiving terminal information motor synchronizing gathers is as follows:
1. initially set up two data memory windows, respectively one the big window being used for depositing sampled point and the wicket for maximum in finding big window that can slide in big window.Receiving terminal often reads an analog-digital conversion result, just this result is stored in big window；Load in wicket is this sampled value and sampled value the most several times before.It follows that system will calculate a few sub-value sums in wicket, and with last and compare, if this and value are more than or equal to last and value, then current wicket is recorded apart from the side-play amount of big Window Start point；If this and value are less than last and value, then continue to retain the side-play amount of last registration.So repeat to compare down, during until big window collection is full, that position that we just can find in this big window and sampled result is maximum the most several times.Due to itself and value maximum, the location determination that we just this maximum can occur is the position that light pulse occurs, thus have found a light pulse synchronizing head section.
In this example, each time slot of TCM-16PPM launched due to transmitting terminal is 10us, and the receiving terminal sampling interval is 2us, and each time slot i.e. acquires 5 sampling points.In the frame lattice of TCM-16PPM example, the form setting synchronous head is as follows :+1 time slot light pulse of+32 time slot low levels of 1 time slot light pulse+1 time slot light pulse of+32 time slot low levels.
In example, set big length of window as 33*5=165, wicket a length of 5.First the value in the two window is all initialized as 0, next reads an analog-digital conversion result every 2us, and write in big window and wicket.Calculate 5 result sums in wicket afterwards, if be currently calculate for the first time and, the most directly preserve current and be worth and currently wicket apart from the side-play amount of big Window Start point；If have existed for and, then relatively more current and preserve with the last time and size, and that value of the greater between the two and the side-play amount of correspondence are preserved.This side-play amount i.e. represents the position that in current big window, continuous 5 sampled value sums are maximum.Sampling the most always and calculate down, during until filling up big window, just have found the position of interior and maximum continuous 5 sampled points of current big window, the i.e. position of light pulse.
The most following, empty above-mentioned big window and wicket, same method finds the position of the light pulse in next big window, record this position, and make comparisons with the position of light pulse in previous group sampled value, if the position that in these two groups, light pulse occurs is identical, then shows and have found a light pulse synchronizing head section；If the position of light pulse is different from the position of light pulse in upper a group in this group, then it is assumed that in upper one group, light pulse position is an erroneous judgement, light pulse in this group is designated as synchronizing first light pulse of head section.So repeating judgement to go down, until detecting and the identical light pulse of synchronization head section defined in frame format, just completing the detection of synchronous head.
In this example, find in first group of 165 sampled point behind the position of light pulse, next position organizing the light pulse in 165 sampled points is found by same method, record this position, and make comparisons with the position of light pulse in 165 sampled points of previous group, if the position that in these two groups of 165 sampled points, light pulse occurs is identical, then shows and have found a light pulse synchronizing head section；If the position of light pulse is different from the position of light pulse in upper one group of 165 sampled point in 165 sampled points of this group, then it is assumed that in upper one group, light pulse position is an erroneous judgement, light pulse in this group sampled point is designated as synchronizing first light pulse of head section.So repeating judgement to go down, until three light pulses synchronized in head section all being detected, just completing the detection of synchronous head.
3. according to TCM-MPPM communication frame format shown in Fig. 5, it is exactly information frame section synchronizing after head section, it is necessary to all stored by information frame after therefore synchronous head being detected, is ready for the detection of slot offset and correction and the extraction of message segment.In order to prevent the information produced owing to time slot offsets backward from missing, when storing information frame section, the sampling point of a part should be gathered more.After sampling point all gathers, calculating the skew of the sampling point received, its principle and method are as follows:
Owing to the form of frame information section determines that, the method for front detection synchronous head therefore can be used to judge the position that light pulse occurs in information frame.Light pulse skew on time slot is as the length of information frame section to be increased and builds up generation, and from this point, this skew does not haves sudden change, i.e. simply gradually embodies along with the increase of transmission data, and side-play amount monotonic increase.Will show in sampled value when slot offset accumulates some.Owing to there being the existence synchronizing head section, the information that the position therefore terminated from synchronization head section starts does not has slot offset, and the skew of time slot is exactly to start accumulation from here afterwards.Owing to receiving what signal collection determined that, whether can be offset by the light pulse that the position of contrast actual samples light pulse out and standard signal concentrate the position of light pulse appearance to carry out judgment frame message segment, and determine that side-play amount is how many.If this information frame does not offset, then directly the sampled result of this information frame will be stored；If this information frame there occurs skew, being then adjusted it according to side-play amount, the information frame after adjusting stores.So repeat down, until whole frame information section process terminates, and by depositing in order without the information frame of skew, this completes TCM-MPPM receiving terminal information motor synchronizing collection.
In this example, each time slot of modulated signal gathers 5 sampling points, then the sampled point for a TCM-16PPM modulated signal adds up to 80, we by its numbered 0 to 79.Assume that skew does not occur in time slot, then we can determine whether that it is on the sampled point of numbering of 0-4 or 5-9 that the peak value of light pulse position sampling inherently occurs in a position.Such as: a certain TCM-16PPM signal light pulse occur on its ' 9 ' position, and the peak value of corresponding sampled value should occur on sampled point 45-49, and its position is 5-9.If sampled peak has occurred on other positions, then may determine that time slot occurs in that skew.Owing to the skew on this time slot is to be gradually increased with the transmission accumulation of time, therefore it is only possible to gradually be displaced to advanced one or delayed one by original without skew, without there is offseting suddenly the situation of multidigit.Therefore, in the event of skew, it is possible to judgement has been in advance or delayed, and correct in time by skew.Continue to transmit on TCM-16PPM signal ' 9 ' position as a example by light pulse above, the peak value of its sampled value should occur on a 45-49, if there is on some 44-48, then may determine that and offset by a sampled point backward, only will need to correct forward one from the data that now can start.
Detection and when correcting slot offset, first calculates the position of sampled point to TCM-16PPM modulated signal according to the form of information frame.Owing to there being the protection section of 32 time slots before TCM-16PPM modulated signal; the most in theory; in 5=240 sampled point of each group of (32+16) *, some 0-159 is the sampled point (totally 160) to protection section, and some 160-239 is the sampled point (totally 80) to TCM-16PPM modulated signal.When detection, it is assumed that occurred in that the skew of time slot, therefore analyst coverage is i.e. sampled point to TCM-16PPM modulated signal at a 160-239() on the basis of, increase the some 0-4 in some 155-159 and next 240 sampled point of group, 90 sampled points altogether.In these 90 sampled points, use and synchronize head section judges that the identical method in light pulse position, to judge the position of light pulse appearance in these 90 sampled points, and is recorded with detecting.Then the individual position of the up-to-date sampled point of the position that the light pulse recorded occurs is judged.If its position is 4 or 9, then illustrate that sampling time slot does not offset, it is not necessary to adjust, directly the sampled value of a 160-239 is sent in the output result array that motor synchronizing gathers；If its position is 3 or 8, then illustrate that sampling time slot offset by a sampled point backward, need to carry out time slot adjustment, the sampled value of a 159-238 is sent in the output result array that motor synchronizing gathers；If its position is 0 or 5, then one sampled point of sampling time slot biased forwards is described, needs to carry out time slot adjustment, the sampled value of a 161-239 and the point 0 of next group is sent in the output result array that motor synchronizing gathers；If its position is 2 or 3, then illustrate that sampling time slot offset by two sampled points backward, need to carry out time slot adjustment, the sampled value of a 158-237 is sent in the output result array that motor synchronizing gathers；If its position is 1 or 6, then two sampled points of sampling time slot biased forwards are described, need to carry out time slot adjustment, the sampled value of the some 0-1 of a 162-239 and next group is sent in the output result array that motor synchronizing gathers.So repeating to judge and correct, until all adjusting complete by whole TCM-16PPM signals, and by storing in order without the information frame of skew, this completes detection and the correction of slot offset.So far, the motor synchronizing collection of information is completed.
It follows that TCM-MPPM receiving terminal needs the data to obtaining after information motor synchronizing collection to carry out adaptive demodulation decoding.Here information is solved and be in harmonious proportion what work decoding had been bound together.
The decoding of TCM-MPPM, uses Viterbi decoding algorithm.Viterbi decoding algorithm essence is a kind of maximum likelihood decoding, and his principle is by comparing estimation decoded signal sequence path in grid chart, finding out the path always measuring maximum.Having first had to subset decoding, because each the corresponding signaling point of individual path in grid chart, the point of chosen distance received signal points distance minimum is optimum signal point.Then, the signaling point calculating each subset and the distance measure receiving between signal, select an optimal signal path, the total path metric of the signal sequence that is allowed to and receives is maximum.
The logic step of TCM-MPPM receiving terminal adaptive demodulation decoding is as follows:
1. pair branch metric calculates and compares, and selects minimum branch metric to eliminate parallel transfer path；
In this example, according to the coder structure figure shown in Fig. 2, and the encoder grid figure shown in Fig. 3, state-transition matrix and coding mapping matrix can be obtained.The 56 groups of 16PPM data messages (often 80 sampled points of group) obtaining sampling calculate the measurement value of a kind of possible state under it arrives.
2. calculate and compare path metric, selecting and store path measures the path of maximum as surviving path, store corresponding buffer status value simultaneously；
In this example, need to calculate respectively the measurement value of a kind of possible state under this group data message arrives, find out the maximum angle value reaching each state, calculate path metric, and preserve state value when obtaining maximum path measurement value and the input value corresponding to state transfer, it is stored in surviving path matrix respectively and survives in mapping matrix.Wherein, path metric is equal to reach each branches of states and measures sum.Next repeat this process, continue to calculate the branch metric of next group signal, update path metric and surviving paths matrix and retain mapping matrix.
3., after arriving certain decoding depth, select one that in surviving path, path metric is maximum to carry out traceback decoding algorithm.Afterwards, traceback decoding result is stored in decoding result cache, this completes the adaptive demodulation decoding of TCM-MPPM receiving terminal.Owing to, during decoding, information dimension is the biggest, and complexity is the highest, but also error code likely occurs, and the method blocked therefore can be used in the case of high information dimension to carry out traceback decoding；
In this example, owing to dimension is less, therefore after the branch metric calculating whole 16PPM signals, then the backtracking in path can be carried out.Now, find out the paths that in 4 paths, path metric is maximum, this path is recalled: in surviving path matrix, find the state transition path of correspondence, and find the input value corresponding with this state transition path as decoding result in coding mapping matrix, this result is stored in decoding result cache.This completes the adaptive demodulation decoding of receiving terminal.
It follows that the COM Debug Assistant that the data in decoding result cache are sent to PC is shown by TCM-MPPM receiving terminal by serial ports.
Information is sent by the PC of emitting portion, coded modulation through TCM-MPPM transmitting terminal, drive laser instrument luminous by drive circuit for laser, optical signal is photoelectrically converted circuit capture, it is transferred to TCM-MPPM receiving terminal through analog to digital conversion circuit, after TCM-MPPM receiving terminal carries out motor synchronizing collection and the adaptive demodulation decoding of information, it is sent to receiving portion PC and shows, this completes the transmittance process of a communication frame.So repeat to send multiple communication frame, once communicate until full detail is sent i.e. to complete.
In order to realize function described in this example, specialized designs develops a set of hardware platform.This platform as core, around includes FLASH, SDRAM, ADC, SMA interface and UART interface with TI company C6000 series DSP chip (TMS320C6713BPYP200).Hardware platform block diagram is as shown in Figure 9.FLASH, SDRAM and ADC are both connected on the EMIF interface of DSP, and sub-miniature A connector is connected on the GPIO interface of DSP, and UART module is connected on the McBsp interface of DSP.FLASH stores the program of communication system, can be automatically loaded in dsp chip during system electrification.SDRAM is for storing the data used in communication process.ADC samples for the waveform producing photoelectric switching circuit.SMA interface is used for driving laser instrument.UART interface is for exchanging data with computer end.
Claims (4)
1. a self adaptation self synchronous TCM-MPPM coded modulation demodulation communication means, including:
Grid coding combined modulation based on multi-system pulse position modulation；
Information motor synchronizing collection and adaptive demodulation and decoding is carried out at receiving terminal；
Described information motor synchronizing gatherer process is as follows:
First receiving terminal carries out synchronous head detection, and after all information synchronized after head section are all gathered and record, correcting program by slot offset and correct the skew of time slot, the TCM-MPPM modulated signal making TCM-MPPM modulated signal and the transmitting received is Tong Bu；
It is characterized in that:
Described combined modulation step includes:
(1) data to be sent of regular length are pressed encoder for convolution codes input length packet, during often group is sequentially sent to encoder for convolution codes, obtains organizing more and export sequences of code bits accordingly；
(2) calculate and will often organize after sequences of code bits is mapped to PPM signal, the position that PPM signal high level occurs；
(3) according to frame format, frame synchronization head section is combined with frame information section, and insert preparation transmitting in caching to be sent；
(4) contents projection sent in caching is gone out by TCM-MPPM transmitting terminal, completes the primary emission of a communication frame.
TCM-MPPM coded modulation the most according to claim 1 demodulation communication means, it is characterised in that: described synchronous head detecting step includes:
(1) two data memory windows, respectively one the big window being used for depositing sampled point and the wicket for maximum in finding big window that can slide in big window are set up；
(2) value in the two window is all initialized as 0；
(3) receiving terminal often reads an analog-digital conversion result, just this result is stored in big window, and this sampled value and before continuous sampled value the most several times are stored in wicket；
(4) calculate this sub-value sum in wicket, and compare with last and value, if this and value are more than or equal to last and be worth, then current wicket is recorded apart from the side-play amount of big Window Start point；If this and value are less than last and value, then continue to retain the side-play amount of last registration；
(5) step (3) is repeated, during until big window collection is full, can find in this big window and that position of the continuous maximum of sampled result the most several times, the location determination that this maximum is occurred is the position that light pulse occurs, namely have found a light pulse synchronizing head section；
(6) repeat step (2), find the position of light pulse in next big window, then make comparisons with the position of light pulse in previous group sampled value, if the position that in these two groups, light pulse occurs is identical, then shows and have found a light pulse synchronizing head section；If the position that in these two groups, light pulse occurs is different, then it is assumed that in previous group, light pulse position is for once to judge by accident, light pulse in this group is designated as synchronizing first light pulse of head section；
(7) repeating step (2), until detecting and the identical light pulse of synchronization head section defined in frame format, completing the detection of synchronous head.
TCM-MPPM coded modulation the most according to claim 1 demodulation communication means, it is characterised in that: described slot offset is corrected program step and is included:
(1) position of sampled point to TCM-MPPM modulated signal is calculated according to the form of information frame；
(2) position that in judgement information frame, in sampled point, light pulse occurs；
(3) position that the position of contrast actual samples light pulse out occurs with light pulse in TCM-MPPM standard signal, it is judged that whether the light pulse of frame information section offsets；
(4) if not offseting, then directly the sampled result of this information frame will be stored；If there occurs skew, being then adjusted it according to side-play amount, the result after adjusting stores；
(5) repeat step (1), until whole frame information section process terminates, and will store in order without the information frame of skew.
TCM-MPPM coded modulation the most according to claim 1 demodulation communication means, it is characterised in that: described adaptive demodulation includes with decoding procedure:
(1) branch metric calculated and compare, selecting minimum branch metric to eliminate parallel transfer path；
(2) calculate and compare path metric, select and store path measure maximum path as surviving path, store corresponding buffer status value simultaneously；Wherein, path metric is equal to reach each branches of states and measures sum；
(3) repeat step (1), continue to calculate the branch metric of next group signal, update path metric and surviving paths matrix and retain mapping matrix；
(4) after arriving certain decoding depth, select one that in surviving path, path metric is maximum to carry out traceback decoding algorithm, traceback decoding result is stored in decoding result cache device.
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1427564A (en) * | 2001-12-20 | 2003-07-02 | 北京六合万通微电子技术有限公司 | Synchronous signal detecting circuit device and detecting method of said device detecting synchronous signal |
| CN101944976A (en) * | 2010-10-11 | 2011-01-12 | 复旦大学 | Gray mapping-based code design method for optimizing Trellis Coded Modulation (TCM) system |
-
2013
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1427564A (en) * | 2001-12-20 | 2003-07-02 | 北京六合万通微电子技术有限公司 | Synchronous signal detecting circuit device and detecting method of said device detecting synchronous signal |
| CN101944976A (en) * | 2010-10-11 | 2011-01-12 | 复旦大学 | Gray mapping-based code design method for optimizing Trellis Coded Modulation (TCM) system |
Non-Patent Citations (4)
| Title |
|---|
| Trellis-Coded Multiple-Pulse-Position Modulation for Wireless Infrared Communications;Hyuncheol Park,John R. Barry;《IEEE TRANSACTIONS ON COMMUNICATIONS》;20040430;第52卷(第4期);643 * |
| Trellis-Coded Pulse-Position Modulation for Indoor Wireless Infrared Communications;David C. M. Lee,Joseph M. Kahn,Malik D. Audeh;《IEEE TRANSACTIONS ON COMMUNICATIONS》;19970930;第45卷(第9期);1080-1086 * |
| Trellis-Coded Pulse-Position Modulation for Optical Communication Systems Impaired by Pulsewidth;Kamran Kiasaleh,Tsun-Yee Yan,Meera Srinivasan;《JOURNAL OF LIGHTWAVE TECHNOLOGY》;19990831;第17卷(第8期);1336-1346 * |
| 一种二脉冲的MPPM编码映射方法研究;秦岭，柯熙政;《西安理工大学学报》;20071231;第23卷(第3期);第271页第1栏第30-32行 * |
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