CN107920040A - Symbol synchronization method, apparatus and equipment - Google Patents

Symbol synchronization method, apparatus and equipment Download PDF

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Publication number
CN107920040A
CN107920040A CN201711071824.8A CN201711071824A CN107920040A CN 107920040 A CN107920040 A CN 107920040A CN 201711071824 A CN201711071824 A CN 201711071824A CN 107920040 A CN107920040 A CN 107920040A
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sampled
signal
coded sequence
symbol
points
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CN107920040B (en
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林淦斌
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Ruijie Networks Co Ltd
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Ruijie Networks Co Ltd
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2668—Details of algorithms
    • H04L27/2673—Details of algorithms characterised by synchronisation parameters
    • H04L27/2675—Pilot or known symbols

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Synchronisation In Digital Transmission Systems (AREA)

Abstract

The embodiment of the present application provides a kind of symbol synchronization method, apparatus and equipment.Wherein, method includes：Over-sampling processing is carried out to the current demand signal from transmitting terminal with local clock frequency, to obtain the first oversampled signals；With frequency N × fT0Down-sampled processing is carried out to the first oversampled signals, to obtain the first down-sampled signal, N is positive integer, fT0It is the desired signal frequencies of transmitting terminal；According to the down-sampled points of reality in single symbol, Edge check is carried out to the first down-sampled signal, to determine the first sampling point of each code element in the first down-sampled signal.The embodiment of the present application can be in the case where ensureing high code member synchronization accuracy, and reduce symbol synchronization realizes difficulty.

Description

Symbol synchronization method, apparatus and equipment
Technical field
This application involves digital communication technology field, more particularly to a kind of symbol synchronization method, apparatus and equipment.
Background technology
In digital communication systems, receiving terminal is in order to which the recovery data-signal from the digital signal received is, it is necessary to certain Speed carries out digital signal periodically to sample, adjudicates, this requires receiving terminal to have the symbol speed with digital signal The clock signal of rate synchronization, to obtain accurate sampling instant.
In order to correctly sample, adjudicate decoding, receiving terminal needs to extract the chip rate with digital signal in a digital signal Synchronous clock signal, this process is symbol synchronization.Had at present using more symbol synchronization mode：Examined based on edge Mode, the mode of all-digital phase-locked loop (Digital Phase Locked Loop, DPLL) of survey.
Wherein, the synchronization accuracy of the mode based on Edge check is poor；Digital phase-locked loop in the mode of all-digital phase-locked loop It is complicated, realize that difficulty is larger.From this analysis, it is badly in need of a kind of symbol for realizing that difficulty is relatively low, synchronization accuracy is higher Synchronization scenario.
The content of the invention
The embodiment of the present application provides a kind of symbol synchronization method, apparatus and equipment, to ensure the synchronous essence of high code member In the case of degree, difficulty is realized in reduction.
The embodiment of the present application provides a kind of symbol synchronization method, including：With local clock frequency to working as from transmitting terminal Front signal carries out over-sampling processing, to obtain the first oversampled signals；With frequency N × fT0To first oversampled signals into The down-sampled processing of row, to obtain the first down-sampled signal, N is positive integer, fT0It is the desired signal frequencies of the transmitting terminal；Root According to the down-sampled points of reality in single symbol in the signal from the transmitting terminal, the described first down-sampled signal is carried out Edge check, to determine the first sampling point of each code element in the first down-sampled signal.
The embodiment of the present application also provides a kind of symbol synchronization device, including：Over-sampling module, for local clock frequency Rate carries out over-sampling processing to the current demand signal from transmitting terminal, to obtain the first oversampled signals；Down-sampled module, is used for With frequency N × fT0Down-sampled processing is carried out to first oversampled signals, to obtain the first down-sampled signal, N is just whole Number, fT0It is the desired signal frequencies of the transmitting terminal；Edge check module, for according in the signal from the transmitting terminal The down-sampled points of reality in single symbol, Edge check is carried out to the described first down-sampled signal, to determine first drop The first sampling point of each code element in sampled signal.
The embodiment of the present application also provides a kind of symbol synchronization equipment, including：Memory and processor；The memory For：Store one or more computer instruction；The processor is used to perform one or more computer instruction, with For：Over-sampling processing is carried out to the current demand signal from transmitting terminal with local clock frequency, to obtain the first over-sampling letter Number；With frequency N × fT0Down-sampled processing is carried out to first oversampled signals, to obtain the first down-sampled signal, N is just Integer, fT0It is the desired signal frequencies of the transmitting terminal；According to the reality in the signal from the transmitting terminal in single symbol Down-sampled points, Edge check is carried out to the described first down-sampled signal, each in the first down-sampled signal to determine The first sampling point of symbol.
The embodiment of the present application also provides a kind of computer-readable recording medium for being stored with computer program, the calculating Machine program is performed the step that can be realized in symbol synchronization method provided by the embodiments of the present application.
In the embodiment of the present application, by down-sampled processing, and combine single in the signal from transmitting terminal being previously obtained Symbol synchronization, is converted to the judgement of sampling number, reduces the realization of symbol synchronization by the down-sampled points of reality in a symbol Difficulty, further combined with Edge check, can make the points surplus of each code element not accumulate next symbol as far as possible, so that more Add the first sampling point for accurately determining each code element, ensure the precision of symbol synchronization.
Brief description of the drawings
In order to illustrate more clearly about the embodiment of the present invention or technical scheme of the prior art, below will to embodiment or Attached drawing needed to be used in the description of the prior art is briefly described, it should be apparent that, drawings in the following description are these Some embodiments of invention, for those of ordinary skill in the art, without creative efforts, may be used also To obtain other attached drawings according to these attached drawings.
Fig. 1 a are the structure diagram for the communication system that one embodiment of the application provides；
Fig. 1 b are 0 corresponding signal waveforms of coded identification in FM0 coding modes；
Fig. 1 c are 1 corresponding signal waveforms of coded identification in FM0 coding modes；
Fig. 1 d are the corresponding signal waveforms of coded identification sequence in FM0 coding modes；
Fig. 1 e are the corresponding Coding conversion state chart relation of coded identification sequence in FM0 coding modes；
Fig. 1 f are the corresponding Coding conversion state chart relation of coded identification sequence in Miller coding modes；
Fig. 2 is the method flow diagram for the symbol synchronization method that another embodiment of the application provides；
Fig. 3 is the method flow diagram for the symbol synchronization method that the another embodiment of the application provides；
Fig. 4 a are the method flow diagram of the down-sampled points of reality in the single symbol that the another embodiment of the application provides；
Fig. 4 b are that the reality in signal of the calculating from transmitting terminal provided by the embodiments of the present application in single symbol is down-sampled The process schematic of points；
Fig. 4 c are the method flow diagram for the correlation computations that the another embodiment of the application provides；
Fig. 5 is the method flow diagram for the symbol synchronization method that the another embodiment of the application provides；
Fig. 6 a are the structure diagram for the symbol synchronization device that one embodiment of the application provides；
Fig. 6 b are the structure diagram for the symbol synchronization device that another embodiment of the application provides
Fig. 7 is the structure diagram for the symbol synchronization equipment that one embodiment of the application provides.
Embodiment
To make the purpose, technical scheme and advantage of the embodiment of the present invention clearer, below in conjunction with the embodiment of the present invention In attached drawing, the technical solution in the embodiment of the present invention is clearly and completely described, it is clear that described embodiment is Part of the embodiment of the present invention, instead of all the embodiments.Based on the embodiments of the present invention, ordinary skill people Member's all other embodiments obtained without creative efforts, belong to the scope of protection of the invention.
Fig. 1 a are the structure diagram for the communication system that one embodiment of the application provides.As shown in Figure 1a, the communication system Including receiving terminal 10 and transmitting terminal 20.It can be in communication with each other between receiving terminal 10 and transmitting terminal 20.Transmitting terminal 20 is mainly used for pair Content of Communication is encoded and sends signal of communication；Receiving terminal 10 is used to receive signal of communication, and decodes and obtain signal of communication institute The Content of Communication to be transmitted.
According to the difference of the communication technology of use, communication system can have polytype.For example, the communication based on 3G technology System, the communication system based on 4G technologies, the communication system based on Wifi and based on radio frequency identification (Radio Frequency Identification, RFID) communication system etc. realized of technology.
Wherein, RFID technique refers to be exchanged for purpose with data to identify, utilizes sensing, radio wave or microwave to carry out The automatic identification technology of contactless two-way communication, tracking and pipe to all physical objects can be realized using this technology Reason.Described to simplify, RFID communication system will be known as based on the communication system that RFID technique is realized.In a kind of communication specification, RFID communication system uses the hyperfrequency (Ultra-High Frequency, UHF) of 900MHz or so, can be further 860MHz-960MHz frequency ranges, can be described as UHF RFID communication systems.What deserves to be explained is RFID communication system is adoptable Frequency range is not limited to 900MHz or so, such as can also use high frequency 13.56MHz, microwave frequency band 2.4GHz etc..
Wherein, UHF RFID communication systems generally comprise RFID tag and RFID reader.RFID labels can be divided into active Label and passive label, the embodiment of the present application do not limit this.Passive label is with read or write speed is fast, memory capacity is big, knows The features such as distance is not remote, cost is low, size is small, is more suitable for the application in the fields such as following logistics, supply chain, library management, To realize that it is possible that " Internet of Things " (Internet of Things, IoT) is provided.
In UHF RFID communication systems, when RFID reader needs to send signal to RFID tag, RFID reader Transmitting terminal 20 can be used as, RFID tag can be used as receiving terminal 10；Correspondingly, when RFID tag needs to send to RFID reader During signal, RFID tag can be used as transmitting terminal 20, and RFID reader can be used as receiving terminal 10.Wherein, RFID tag is read with RFID Writing device can use but be not limited to：Two-phase space code coding mode (Bi-Phase Space, abbreviation FM0) coding mode, Miller (Miller) coding mode.
In FM0 coding modes, the signal waveform of a symbol continues two pulse periods, and two pulse periods are one A code-element period.The wave characteristics of FM0 are：Waveform upset can occur for the border between symbol and symbol；Meanwhile in transmission symbol When " 0 ", need to overturn in a code-element period；When transmitting symbol " 1 ", then need to keep waveform stabilization in code-element period.Fig. 1 b Two kinds of signal waveforms in code-element period during transmission symbol " 0 " are shown.Fig. 1 c show symbol during transmission symbol " 1 " Two kinds of signal waveforms in cycle.Fig. 1 d show the multiple signal waveforms for including the two code elements cycle.As shown in Figure 1 d, it is adjacent Waveform upset can occur for the border between symbol, and the corresponding signal waveform of symbol " 1 " keeps steady in a code-element period Fixed, there are the upset of primary wave shape in a code-element period for the corresponding signal waveform of symbol " 0 ".
In FM0 coding modes, there are 4 kinds of encoding states, as shown in fig. 1b and fig. lc.The first half of symbol " 0 " will be represented A code-element period is high level, and rear half of code-element period is denoted as encoding state S2 for low level signal waveform, will represent symbol Preceding half of code-element period of " 0 " is low level, and rear half of code-element period is denoted as encoding state S3 for the signal waveform of high level. To represent in a code-element period of symbol " 1 " is always that low level signal waveform is marked as encoding state S1；Accorded with representing The signal waveform token in one code-element period of number " 1 " being always high level is encoding state S4.
Can mutually it be changed between 4 kinds of encoding states in FM0 coding modes, the transformational relation between 4 kinds of encoding states Meet that FM0 coding modes are required being overturn to the border between adjacent symbol.As shown in Fig. 1 e, turn between 4 kinds of encoding states The relation of changing includes：Encoding state S1 can jump to encoding state S3 and S4, and encoding state S2 can jump to encoding state S1 And S2；Encoding state S3 can jump to encoding state S3 and S4, and encoding state S4 can jump to encoding state S1 and S2.
Miller coding modes can be understood as two coding stages, i.e. basic coding stage and modulating-coding stage. Basic coding stage, the signal waveform of a symbol continue two pulse periods, and two pulse periods are a code-element period. The wave characteristics of Miller are：When transmitting symbol " 0 ", do not overturn in a code-element period；When transmitting symbol " 1 ", one Need to carry out once inside out in a code-element period；When transmitting two continuous " 0 ", the border between adjacent symbol needs to send out Raw waveform upset；When transmitting two continuous " 1 ", the border between adjacent symbol need not be overturn.In modulating-coding rank Section, by original coding waveform modulated into subcarrier, subcarrier can be understood as the pulse sequence that frequency is symbol frequency integral multiple Row, specific multiple sends the relevant parameter in instruction by reader and determines, such as can take 2 times, 4 times or 8 times etc..
In Miller coding modes, 4 kinds of encoding states are equally existed, and can mutually turn between 4 kinds of encoding states Change, the transformational relation between 4 kinds of encoding states meets that Miller coding modes overturn the border between adjacent symbol and requires. As shown in Figure 1 f, the transformational relation in Miller coding modes between 4 kinds of encoding states includes：Encoding state S1 can be redirected To encoding state S2 and S4, encoding state S2 can jump to encoding state S3 and S4；Encoding state S3 can jump to coding State S1 and S2, encoding state S4 can jump to encoding state S1 and S3.
For RFID reader, after the signal of FRID labels transmission is received, it can be used according to FRID labels Coding mode, such as the coding rule of FM0 coding modes or Miller coding modes, with identical with the signal received Chip rate periodically sample and adjudicate.This means RFID reader (i.e. receiving terminal) needs one with receiving Signal chip rate synchronization clock signal, accurately to be sampled and be adjudicated the moment.Symbol synchronization refers to from reception To signal in the extraction clock signal synchronous with the chip rate of the signal process, be correctly to sample, adjudicate and translate The basis of code.
In communication system provided by the embodiments of the present application, transmitting terminal 20 should be with a desired signal frequencies fT0Produce letter Number.Wherein, desired signal frequencies fT0The frequency that to be transmitting terminal 20 make an appointment with receiving terminal 10, such as receiving terminal 10 lead in advance Instruction is crossed by desired signal frequencies fT0It is handed down to transmitting terminal 20.However, in practical applications, since is produced from the inside of transmitting terminal 20 Raw clock is not accurate enough, causes the actual frequency f of the signal of the transmission of transmitting terminal 20TWith desired signal frequencies fT0There are certain Deviation.By taking UHF RFID communication systems as an example, the clock produced inside RFID tag is not accurate enough, causes RFID tag to send To the backscatter link frequency (Backscatter Link Frequency, BLF) of the signal of RFID reader, there are maximum ± 22% deviation.For example, it is 320kHz that if RFID reader, which requires the BLF of RFID label return signals, label is actual to be returned The signal BLF returned may fall between (1-22%) × 320~(1+22%) × 320kHz.
For receiving terminal 10, it is necessary to the signal there are frequency departure that transmitting terminal 20 returns is carried out correct sampling and Judgement, to identify the initial position of each code element, condition is provided for follow-up correct decoding.
In the present embodiment, receiving terminal 10 by it is down-sampled processing, be previously obtained single code in the signal from transmitting terminal 20 The down-sampled points of reality and Edge check in member are combined, and each code element adopts in the definite signal from transmitting terminal 20 The initial position of sample starting point, i.e. each code element.
Since from exemplified by the current demand signal of transmitting terminal 20, receiving terminal 10 receive transmitting terminal 20 transmission current demand signal after, Over-sampling processing is carried out to current demand signal with local clock frequency first, to obtain the first oversampled signals.Here why claim It is because the local clock frequency of receiving terminal 10 is far above the desired signal frequencies f of transmitting terminal 20 for over-samplingT0, be higher by times Number can be determined on a case-by-case basis, such as local clock frequency can be desired signal frequencies fT0200 times.
Then, receiving terminal 10 is with frequency N × fT0Down-sampled processing is carried out to the first oversampled signals, to obtain the first drop Sampled signal, N are positive integers.Here it is because frequency N × f why to be known as down-sampledT0Far below receiving terminal 10 local when Clock frequency, the value of N can be determined on a case-by-case basis.
If the actual frequency f for the signal that transmitting terminal 20 is sentTWith desired signal frequencies fT0Identical, then first is down-sampled Can all there is N number of sampled point in each code element of signal, then every N sampled point is a symbol since first sampled point, It may determine that the first sampling point number of each code element.But in practical applications, there is the probability of this ideal situation very It is low, in most of situation even whole circumstances, the actual frequency f for the signal that transmitting terminal 20 is sentTWith desired signal frequencies fT0 There are certain deviation.This means the down-sampled points actually fallen in each code element are not N number of, but R.R representation theories On can fall the down-sampled points in each code element, by following formula (1) understand R be non integer value.Below by formula (1) Derivation illustrate：
In above-mentioned formula (1), fR=N × fT0；N ' represents down-sampled in each code element closest to that can fall in theory The integer value of points；ε is frequency departure, and α is the non-fractional part divided exactly.Because sampling number can not take fractional part, Adopted closest to the integer value N ' that can fall the down-sampled points in each code element in theory as the actual drop in single symbol Number of samples.
In the present embodiment, the reality that receiving terminal 10 is obtained in the signal from transmitting terminal 20 in single symbol is down-sampled Determine that the sampling of each code element in the first down-sampled signal originates based on points N ', and by the down-sampled points N of the reality ' Point.In the present embodiment, the actual drop that receiving terminal 10 is obtained in the signal from transmitting terminal 20 in single symbol is not limited to adopt The mode of number of samples, the side of every down-sampled points of reality that can be obtained in the signal from transmitting terminal 20 in single symbol Formula is suitable for the present embodiment.For example, receiving terminal 10 can be estimated out from transmitting terminal by a lead code correlator array The down-sampled points of reality in 20 signal in single symbol.
Understood based on above-mentioned formula (1), reality of the receiving terminal 10 in based on the signal from transmitting terminal 20 in single symbol The down-sampled points N in border ' to determine the first sampling point of each code element in down-sampled signal when, can also there are one in each code element Fixed points surplus (the non-fractional part divided exactly), the points surplus can accumulate next symbol, and this points surplus is tired out Product can cause error code to produce after multiple symbols.Based on this, in order to ensure symbol synchronization precision, receiving terminal 10 is according to reality The down-sampled points N in border ' carry out combining Edge check on the basis of symbol synchronization, i.e. according to single in the signal from transmitting terminal 20 The down-sampled points of reality in a symbol, carry out Edge check, to determine in the first down-sampled signal to the first down-sampled signal The first sampling point of each code element.
It can be seen from the above that receiving terminal is by down-sampled processing, and combine the reality in the signal from transmitting terminal in single symbol Symbol synchronization, is converted to the judgement of sampling number by the down-sampled points in border, reduces the difficulty of realizing of symbol synchronization, further With reference to Edge check, the points surplus of each code element can be made not accumulate next symbol as far as possible, so as to more accurately determine The first sampling point of each code element, ensures the precision of symbol synchronization.
The process that symbol synchronization is carried out to receiving terminal is described in detail the application following methods embodiment.
Fig. 2 is the method flow diagram of the symbol synchronization method of another offer of the embodiment of the present application.As shown in Fig. 2, this method Including：
Step 201, with local clock frequency carry out over-sampling processing to the current demand signal from transmitting terminal, to obtain the One oversampled signals.
Step 202, with frequency N × fT0Down-sampled processing is carried out to first oversampled signals, is adopted with obtaining the first drop Sample signal, N are positive integers, fT0It is the desired signal frequencies of transmitting terminal.
The down-sampled points of reality in step 203, signal of the basis from transmitting terminal in single symbol, to described first Down-sampled signal carries out Edge check, to determine the first sampling point of each code element in the first down-sampled signal.
In the present embodiment, since from exemplified by the current demand signal of transmitting terminal.In theory, transmitting terminal should be with ideal signal Frequency fT0Send current demand signal.Receiving terminal receives the current demand signal that transmitting terminal is sent, and with local clock frequency to current demand signal Over-sampling is carried out, obtains oversampled signals.For ease of distinguishing and describing, oversampled signals here are known as the first over-sampling Signal.Wherein, the local clock frequency of receiving terminal is far above the desired signal frequencies f of transmitting terminalT0, the multiple being specifically higher by can It is determined on a case-by-case basis, such as local clock frequency can be desired signal frequencies fT0200 times.
In step 202, receiving terminal is with frequency N × fT0Down-sampled processing is carried out to the first oversampled signals, obtains a drop Sampled signal.For ease of distinguishing and describing, down-sampled signal here is known as the first down-sampled signal.Wherein, receiving terminal with Fixed frequency N × fT0Down-sampled processing is carried out again to the signal after local clock frequency over-sampling, it is possible to achieve receiving terminal is believed The normalization of number frequency, easy to simplify the processing logic of receiving terminal.
In the ideal situation, each code element of the first down-sampled signal should include N number of sampled point.But in practical application In, since transmitting terminal internal clocking is not accurate enough, the actual frequency f of the current demand signal from transmitting terminalTAnd desired signal frequencies fT0Between there are deviation.The sampling number actually included in each code element that this deviation will cause the first down-sampled signal is simultaneously It is non-N number of.Understood referring to above-mentioned formula (1), due to the actual frequency f of current demand signalTWith desired signal frequencies fT0Between deviation The sum of it is an Integer N to cause to fall on the sampling number in each code element ' and certain point number surplus (the non-fractional part divided exactly).
In the present embodiment, receiving terminal depends on the down-sampled point of reality in single symbol in the signal from transmitting terminal Number N '.Signal here from transmitting terminal is to refer to any signal from transmitting terminal.It is " single in the signal from transmitting terminal The down-sampled points N of reality in symbol ' " represent：Every signal from transmitting terminal, is passing through receiving terminal with local clock frequency Rate carries out over-sampling again with frequency N*fT0Carry out the actual samples in each code element in the down-sampled down-sampled signal obtained afterwards Points are N '.Wherein, actual down-sampled points N ' letter before current demand signal that can be receiving terminal send according to transmitting terminal Number estimate closest to the integer that can fall the down-sampled points in each code element in theory.
On the basis of the above, the down-sampled points N of reality since receiving terminal from the signal of transmitting terminal in single symbol ' Based on estimate the first sampling point of each code element in the first down-sampled signal.Furthermore, it is contemplated that the presence of points surplus, is Avoid each code element points surplus accumulate cause multiple symbols to next symbol after phase offset cause error code to produce, The down-sampled points N of reality of the receiving terminal in the signal from transmitting terminal in single symbol ' on the basis of combine Edge check, So that the points surplus of each code element does not accumulate next symbol as far as possible, the points surplus of a upper symbol is reduced in next code The adverse effect produced in first deterministic process, so as to accurately determine the first sampling point of each code element, ensures symbol synchronization Precision.
In the present embodiment, by down-sampled processing, and the reality in the signal from transmitting terminal in single symbol is combined Symbol synchronization, is converted to the judgement of sampling number by down-sampled points, and reduce symbol synchronization realizes difficulty, further knot Edge check is closed, the points surplus of each code element can be made not accumulate next symbol as far as possible, so as to more accurately determine every The first sampling point of a symbol, ensures the precision of symbol synchronization.
In the above-described embodiments, it is necessary to carry out Edge check to the first down-sampled signal.Edge check is mainly detection code The edge point of first waveform, edge point are exactly the changed point of both sides level, and the situation of change of both sides level can be from high electricity Flat saltus step be low level or from low transition be high level.Wherein, Edge check can have a variety of implementations. Such as exclusive or calculating can be done to the level value of neighbouring sample point, the electricity of neighbouring sample point is illustrated if exclusive or result is " 1 " Level values are different, and there occurs edge transition, illustrates that the level value of neighbouring sample point is identical if exclusive or result is " 0 ", does not occur Edge transition.In addition to the implementation, FIG. 3 below illustrated embodiment provides the embodiment of another Edge check.
Fig. 3 is the method flow diagram of the symbol synchronization method of the another offer of the embodiment of the present application.As shown in figure 3, this method Including：
Step 301, with local clock frequency carry out over-sampling processing to the current demand signal from transmitting terminal, to obtain the One oversampled signals.
Step 302, with frequency N × fT0Down-sampled processing is carried out to first oversampled signals, is adopted with obtaining the first drop Sample signal, N are positive integers, fT0It is the desired signal frequencies of transmitting terminal.
Step 303, successively handled the symbol in the first down-sampled signal, when current symbol is arrived in processing, according to The down-sampled points of reality in the first sampling point of previous symbol and signal from transmitting terminal in single symbol, determine current Symbol estimates starting point.
Step 304, estimate in starting point and its several front and rear sampled point from described, obtains and continuous L afterwards is a adopts It is positive integer that the absolute value of the difference of sampling point, which is all higher than the sampled point of given threshold as edge point, L,.
Step 305, according to the edge point, determine the first sampling point of the current symbol.
Step 306, judge whether also have untreated symbol in the described first down-sampled signal；If the determination result is YES, Return to step 303；If judging result is no, terminate this symbol synchronization operation.
The description as described in step 301 and 302 refers to the record in embodiment illustrated in fig. 2, and details are not described herein.
In step 303, each code element in the first down-sampled signal is handled successively.Here processing is main It is the first sampling point for identifying each code element.Wherein, can if current symbol is the first symbol in the first down-sampled signal Directly to regard some sampled point of signal incipient stage as its first sampling point.Some sampled point can be first sampled point, Second sampled point or the 3rd sampled point etc., depending on specific visual application scenarios.If current symbol is not the first down-sampled letter First symbol in number, then can be in the first sampling point according to previous symbol and the signal from transmitting terminal in single symbol The down-sampled points of reality determine that current symbol estimates starting point.Because a upper symbol is worked as there may be points surplus The actual samples starting point of preceding symbol is likely located at this and estimates starting point, it is also possible to is estimated positioned at this near starting point.
If the first sampling point of previous symbol is n-th of sampled point, the starting point of estimating of current symbol is that the n-th+N ' is a Sampled point.For example, it is assumed that the first sampling point of previous symbol is the 10th sampled point in the first down-sampled signal, and it is single The actual point of symbol is N '=8, then the starting point of estimating of current symbol samples for the 18th in the first down-sampled signal Point.
Further, it is contemplated that the down-sampled points N of the reality of single symbol in the signal from transmitting terminal ', it may be possible to most connect The nearly integer value that can fall the down-sampled points in single symbol in theory, and except actual down-sampled points in each code element Outside N ', it is also possible to can have points surplus.For example, 7 sampled points are of virtually in a down-sampled obtained symbol, separately Actually there are 9 sampled points in one symbol, and the down-sampled points of reality in single symbol are 8 points.In this case, if The initial position of each code element is determined with 8 points, then symbol synchronization can be caused to malfunction.
To avoid drawbacks described above, determine current symbol estimate starting point after, estimate starting point and its adjacent at this Edge check is carried out in the range of sampled point.Above-mentioned steps 304 essentially describe the another embodiment of Edge check.At this In embodiment, from estimating in starting point and its several front and rear sampled point for current symbol, obtain and continuous L afterwards It is positive integer that the absolute value of the difference of sampled point, which is all higher than the sampled point of given threshold as edge point, L,.Wherein, the value of L can It is empirically derived, for example, L can take 2,3,4,5 etc..By lot of experiment validation, when L takes 3, Edge check accuracy compared with It is high.
For example, starting point is estimated as n-th point on the first down-sampled signal, n-th point of several front and rear sampled points For：N-th-△ n o'clocks is to the 2 △ n+1 points included altogether between the n-th+△ n points, and △ n are integer, △ n >=1.From the n-th-△ n A point starts, calculate the n-th-△ n points with its afterwards continuously L sampled point difference absolute value.Represent that first is down-sampled with X The corresponding sample sequence of signal, calculates the n-th-△ n points and absolute value of difference of continuous L sampled point can represent after it For：Calculate | Xn-△n -Xn-△n+1|、|Xn-△n-Xn-△n+2|…|Xn-△n-Xn-△n+L|, and judge it is that above-mentioned absolute value calculates the result is that It is no to be all higher than given threshold.The given threshold can be 0 or the number more than 0.If the n-th-△ n points and continuous L after it are a The absolute value of the difference of sampled point is all higher than given threshold, then there are larger level with L point after it for the n-th-△ n points Difference, it is believed that there occurs level saltus step at the n-th-△ n points, it may be determined that the n-th-△ n points are edge point.
If the n-th-△ n points and absolute value of difference of continuous L sampled point is not both greater than given threshold after it, Continue to judge the n-th-△ n+1 points and whether the absolute value of the difference of continuous L sampled point is all higher than given threshold after it, directly To the n-th-△ n o'clocks to found between the n-th+△ n points satisfaction and after it difference of continuous L sampled point absolute value it is equal More than given threshold sampled point or not the n-th-△ n o'clocks to found between the n-th+△ n points meet with it after it is continuous Untill the absolute value of the difference of L sampled point is all higher than the sampled point of given threshold.If finding edge point, i.e., with connecting after it The absolute value for continuing the difference of L sampled point is all higher than the sampled point of given threshold, then enters step 305；If edge is not found Point, then can estimate starting point as its first sampling point using current symbol.
After definite edge point, the first sampling point of current symbol can be determined according to the edge point.Alternatively, may be used Using the first sampling point by the edge point as current symbol, or also can using first point after the edge point as work as The first sampling point of preceding symbol, or can also be using the l-th point after the edge point as current symbol first sampling point, Depending on specific visual actual conditions are flexible.For example, determine the n-th-△ n points as after edge point, can using the n-th-△ n points as The first sampling point of current symbol, first sampling point that can also be using the n-th-△ n+1 points as current symbol, or by n-th- First sampling point of the △ n+L points as current symbol.In the present embodiment, according to single code in the signal from transmitting terminal What the down-sampled points of reality in member determined current symbol estimates starting point, to estimating starting point and its neighbouring several points Edge check is carried out, the interference of phase margin, ensure that higher symbol caused by eliminating the points surplus in each code element Synchronization accuracy.
In above-described embodiment or following embodiments, the current demand signal from transmitting terminal is carried out in element synchronization Dependent on the down-sampled points of reality in the signal of transmitting terminal in single symbol.Optionally, in the signal from transmitting terminal The down-sampled points of reality in single symbol can obtain in advance before symbol synchronization, can also be in the process of symbol synchronization In in real time calculate obtain.Wherein, the mistake of the down-sampled points of reality in single symbol is obtained ahead of time in the signal from transmitting terminal Journey can perform before Fig. 2 or embodiment illustrated in fig. 3.As shown in fig. 4 a, the process of actual samples points, which is obtained ahead of time, to be included：
Step 401, with local clock frequency to from transmitting terminal signal carry out over-sampling processing, to obtain the second mistake Sampled signal.
Step 402, with frequency N × fT0Down-sampled processing is carried out to second oversampled signals, is adopted with obtaining the second drop Sample signal, N are positive integers, fT0It is the desired signal frequencies of transmitting terminal.
Step 403, according to 2K+1 groups coded sequence the lead code in the described second down-sampled signal is carried out respectively it is related Calculate, to obtain 2K+1 lead code correlated results；Wherein, the coding shape that each coded sequence represents in 2K+1 groups coded sequence State is determined that the points of coded sequence are one in N ± i in every group of coded sequence, i=by the coding mode that transmitting terminal uses 0,1,2 ... K, K are nonnegative integers, and the size of K is related to N.
Step 404, obtain the corresponding coding of lead code correlated results maximum in the 2K+1 lead code correlated results The points of sequence, as the down-sampled points of reality in the signal of transmitting terminal in single symbol.
On the basis of Fig. 2 or embodiment illustrated in fig. 3, in step 401 signal from transmitting terminal can be transmitting terminal to Receiving terminal sends the signal before current demand signal, such as can be transmitting terminal for the request of receiving terminal or instruct to receiving terminal The request signal that the answer signal or transmitting terminal of return are actively sent to receiving terminal.
Preferably, when the signal from transmitting terminal is the answer signal that transmitting terminal is returned to receiving terminal in step 401, Can be first answer signal that transmitting terminal is returned to receiving terminal.By taking FRID communicates as an example, FRID labels are to RFID reader First answer signal returned is the answer signal for carrying 16 random codes (RN16).When coming from transmitting terminal in step 401 Signal when being the request signal that transmitting terminal is actively sent to receiving terminal, can be that transmitting terminal is actively sent to receiving terminal the One request signal.
Wherein, when transmitting terminal sends first response/request signal to receiving terminal, just estimate out from transmitting terminal The down-sampled points N of reality in signal in single symbol ', can be directly actual down-sampled using this during subsequent communications Points N ' symbol synchronization is carried out, without computing repeatedly actual down-sampled points N in subsequent symbol synchronizing process ', on the whole The efficiency of symbol synchronization can be improved.
In step 401, receiving terminal can use local clock frequency f as sample frequency to the signal from transmitting terminal Over-sampling is carried out, to obtain oversampled signals.For ease of being carried out with the first oversampled signals in Fig. 2 or embodiment illustrated in fig. 3 Distinguish, oversampled signals here are known as the second oversampled signals.Although oversampled signals here are known as the second over-sampling Signal, but occur on time of occurrence prior to the first oversampled signals, therefore " first " in the embodiment of the present application, " the The descriptions such as two " neither limit number, also do not limit sequencing, only to the differentiation of title.Wherein, f is much larger than fTOr fT0, therefore referred to as over-sampling will be sampled to the signal from transmitting terminal with local clock frequency f here.fTFor from transmission The actual frequency of the signal at end, with fT0There is certain deviation, but be not much different.Wherein, with higher local clock frequency f to coming Over-sampling is carried out from the signal of transmitting terminal, is conducive to be lifted the time domain resolving power and signal-to-noise ratio of the second oversampled signals.
In step 402, with frequency N × fT0Down-sampled processing is carried out to the second oversampled signals, obtains a down-sampled letter Number.For ease of being distinguished with the first down-sampled signal in Fig. 2 or embodiment illustrated in fig. 3, down-sampled signal here is claimed For the second down-sampled signal.fT0It is the desired signal frequencies of transmitting terminal.In the ideal situation, the reality of the signal from transmitting terminal Border frequency fTWith fT0It is identical, obtain each code element of the second down-sampled signal after down-sampled to the progress of the second oversampled signals On should have N number of sampled point.But during practical communication, it is limited to the precision of transmitting terminal internal clocking, fTWith fT0Between deposit In deviation.It is N that the quantity of the sampled point actually included in each code element that this deviation will cause the second down-sampled signal, which is not, A, specific derivation process can be found in formula (1), and details are not described herein.
The down-sampled points of reality grown in the second down-sampled signal in each code element can be derived by formula (1) It is not N number of, but N ' is a, but the actual drop that can not directly obtain in the second down-sampled signal in each code element is adopted Number of samples N '.In general, the clock frequency deviation of transmitting terminal be stablize it is constant be within some time in other words it is stable, this Mean for any signal from transmitting terminal, over-sampling is being carried out again with frequency with local clock frequency f by receiving terminal N×fT0Carry out it is down-sampled after down-sampled points of reality in obtained down-sampled signal in single symbol it is all identical.Therefore, may be used To estimate the down-sampled points of reality in the second down-sampled signal in each code element as in the signal of transmitting terminal The down-sampled points N of reality in single symbol '.
In the present embodiment, the signal from transmitting terminal includes lead code, and lead code is effective in positioning signal The initial position of data.The lead code that different coding mode uses is different.Once it is determined that coding mode, lead code is also just true It is fixed.For example, in FM0 coding modes, a kind of corresponding coded identification sequence of lead code can be " 1010v1 ", wherein v tables Show the waveform beyond FM0 encoding states, referred to as break rules symbol；Second lead code can be attached before " 1010v1 " a string it is continuous 12 coded identifications " 0 ".In addition, once it is determined that coding mode, the encoding state under the coding mode also just uniquely determines .For example, FM0 coding modes have 4 kinds of encoding states, reference can be made to shown in Fig. 1 b, Fig. 1 c and Fig. 1 e.In another example Miller is compiled Code mode has 4 kinds of encoding states, reference can be made to Fig. 1 f.
In the present embodiment, incorporating parametric N, arrange parameter K, i take 0,1,2 ..., and K, K reflect transmitting terminal to a certain extent The deviation of system clock, the down-sampled points of reality in the second down-sampled signal in each code element are probably one in N ± i. With frequency fT0The corresponding signal waveform of each encoding state under the coding mode that transmitting terminal uses is produced, with frequency (N ± i) * fT0 In each frequency the corresponding signal waveform of each encoding state is sampled, so as to obtain 2K+1 group coded sequences.Its In, each group of coded sequence includes the coded sequence sampled to the corresponding signal waveform of each encoding state.Each group The points of coded sequence in coded sequence are one kind in N ± i, and the points of the coded sequence in different groups are different.
, can be according to the Coding conversion state chart relation of coding mode for the coded sequence in each group of coded sequence (as shown in Fig. 1 e or Fig. 1 f) is produced and is included the benchmark preamble sequence of corresponding sampling number in single symbol, and then is based on base Lead code in quasi- preamble sequence and the second down-sampled signal, which carries out correlation computations, can obtain in the second down-sampled signal each The down-sampled points of reality in symbol.
Then, as shown in Figure 4 b, phase is carried out to the lead code in the second down-sampled signal with 2K+1 groups coded sequence respectively Close and calculate, to obtain 2K+1 lead code correlated results, according to the essence of correlation computations, select the lead code of maximum is related to tie The points of the corresponding coded sequence of fruit, as the down-sampled points of reality in each code element in the second down-sampled signal, that is, come The down-sampled points of reality from the signal of transmitting terminal in single symbol.
By taking the corresponding signal waveform of each encoding state of any coding mode as an example, signal wave corresponding to each encoding state When shape is sampled, the points of sampling can be one in N ± i, and i=0,1,2 ... K, K are nonnegative integers.Then according to sampling The difference of points, can obtain 2K+1 group coded sequences.For example, during i=0,1st group coded sequence of the points for N is obtained；I= When 1,2nd group coded sequence of the points for N+1 is obtained, and points are the 3rd group of coded sequence of N-1；And so on, i= During K, 2k group coded sequence of the points for N+K is obtained, and points are the 2k+1 group coded sequences of N-K.
As shown in Fig. 1 b and 1c, FM0 coding modes include encoding state S1~S4, then include in every group of coded sequence To encoding state S1~S44 coded sequences that corresponding signal waveform samples.Correspondingly, Miller coding modes are also wrapped Include encoding state S1~S4, then include in every group of coded sequence to encoding state S1~S4Corresponding signal waveform samples to obtain 4 coded sequences.Coded sequence is illustrated by taking FM0 coding modes as an example below.
It is assumed that N=8, K=2, then can obtain 2K+1=5 group coded sequences.High level, and number are represented with numerical value 1 Value -1 represents low level, with Sx yRepresent in y group coded sequences to encoding state SxThe volume that corresponding signal waveform samples Code sequence.
In i=0, the points of each coded sequence are N ± 0=8 in the 1st group of coded sequence, then S1 1For [1,1,1,1,1, 1,1,1], S2 1For [1,1,1,1, -1, -1, -1, -1], S3 1For [- 1, -1, -1, -1,1,1,1,1], S4 1For [- 1, -1, -1, - 1,-1,-1,-1,-1]；
In i=1, the points of each coded sequence are N-1=7 in the 2nd group of coded sequence, then S1 2For [1,1,1,1,1,1, 1], S2 2For [1,1,1,1, -1, -1, -1], S3 2For [- 1, -1, -1, -1,1,1,1], S4 2For [- 1, -1, -1, -1, -1, -1, - 1]；
In i=1, the points of each coded sequence are N+1=9 in the 3rd group of coded sequence, then S1 3For [1,1,1,1,1,1, 1,1,1], S2 3For [1,1,1,1, -1, -1, -1, -1, -1], S3 3For [- 1, -1, -1, -1,1,1,1,1,1], S4 3For [- 1 ,- 1,-1,-1,-1,-1,-1,-1,-1]；
In i=K=2, the points of each coded sequence are N-2=6 in the 4th group of coded sequence, then S1 4For [1,1,1,1, 1,1], S2 4For [1,1,1, -1, -1, -1], S3 4For [- 1, -1, -1,1,1,1], S4 4For [- 1, -1, -1, -1, -1, -1]；
In i=K=2, the points of each coded sequence are N+2=10 in the 5th group of coded sequence, then S1 5For [1,1,1,1, 1,1,1,1,1,1], S2 5For [1,1,1,1,1, -1, -1, -1, -1, -1], S3 5For [- 1, -1, -1, -1, -1,1,1,1,1,1], S4 5For [- 1, -1, -1, -1, -1, -1, -1, -1, -1, -1].
The coded sequence of above-mentioned different points is only a kind of example, the other volumes deformed based on above-mentioned example Code sequence is also applied for the embodiment of the present application.
From above-mentioned example, the points of each coded sequence are identical in one group of coded sequence.For example, first group of volume The points of each coded sequence are 8 in code sequence, and the points of each coded sequence are 7, etc. in second group of coded sequence.
Wherein, the size of K is related to N, and N values are bigger, the increase of being also adapted to property of K.For example, during N=8, K can be with 3, N=15 When, K can take 5.
, can be with when carrying out correlation computations to the lead code in the second down-sampled signal respectively with 2K+1 groups coded sequence 2K+1 groups coded sequence is carried out correlation computations by identical mode with the lead code in the second down-sampled signal respectively.
In a kind of optional embodiment, by taking first group of coded sequence in 2K+1 group coded sequences as an example, illustrate and Lead code in second down-sampled signal carries out the process of correlation computations.Wherein, first group of coded sequence can be that 2K+1 groups are compiled Any one group of coded sequence in code sequence.As illustrated in fig. 4 c, which includes：
Step 4031, the Coding conversion state chart relation according to coding mode, from first group of coded sequence selection with it is leading The matched coded sequence of each code element of code.
Step 4032, using with the matched coded sequence of each code element of lead code carry out each code element of lead code Correlation computations, to obtain the correlated results of each code element of lead code.
Step 4033, add up the correlated results of each code element of lead code, to obtain first group of coded sequence pair The lead code correlated results answered.
In step 4031, energy measuring can be carried out to lead code, to determine the start bit of each code element in lead code Put.On energy measuring reference can be made to the prior art, is not detailed herein.
On lead code is determined behind the initial position of each code element, for each symbol in lead code, according to symbol Corresponding coded identification, it may be determined that the corresponding coded sequence of the symbol.For example, by taking the lead code 1010v1 of FM0 as an example, first The corresponding coded identification of a symbol is 1, and symbol waveform is high level, and then symbol 1 corresponds to encoding state S1, then the symbol Corresponding coded sequence can be S1 1、 S1 2…S1 2K+1.The corresponding coded identification of second symbol is 0, and symbol waveform is first low Level high level again, then encoding state is encoding state S3 by S1 saltus steps, then the corresponding coded sequence of the symbol is S3 1、 S3 2…S3 2K+1。
, can be by the corresponding volume of first symbol by taking first symbol in lead code as an example in step 4032 Code sequence does correlation computations to obtain the correlated results of first symbol.For example, the sampled point in first symbol is X1= [x1x2x3x4x5x6x7x8x9], first coded sequence that first symbol corresponds in first group of coded sequence is S1 1=[1, 1,1,1,1,1,1,1,1].When carrying out correlation computations, to X1 and S1 1Correlation computations are done, obtain correlated results C<X1, S1 1>。
Wherein, C is calculated<X1, S1 1>When, can putting in order according to sampled point, first calculate x1And S1 1In the phase of first 1 Close as a result, simultaneously calculating x after the same method2And S1 1In the correlation calculation result of second 1, arrive x until calculating8With S1 1In The correlation calculation result of the 8th 1.Be calculated 8 correlated results are added up, you can obtain the corresponding C of first symbol< X1, S1 1>。
When calculating the correlation calculation result of any symbol and coded sequence, according to the feature of orthogonal coding, if symbol with The value of the corresponding point in position is identical in coded sequence, then its correlated results is 1, if it is different, then correlated results is 0.
Based on the above process, each code element in lead code can be obtained and correspond to coded sequence with first group of coded sequence Between correlated results.
In step 4033, each symbol of lead code and corresponding encoded sequence in first group of coded sequence are determined After correlated results, the correlated results of each code element and corresponding encoded sequence in first group of coded sequence can be added up, with Obtain the corresponding lead code correlated results of first group of coded sequence.For example, the related knot of the corresponding lead code of first group of coded sequence FruitThe total number of M presentation code sequences.
According to 4031~step 4033 of above-mentioned steps, the corresponding lead code correlated results of other groups of coded sequences can obtain.
Optionally, in the embodiment of the present application, transmitting terminal can compile transmission signal using orthogonal coding mode Code, such as FM0 coding modes, FM1 coding modes, Miller code or Manchester's code (Manchester).Therefore, true After determining 2K+1 lead code correlated results, the correlated results of maximum can be chosen, that is, from C1、C2... and C2K+1Middle selection Maximum Cmax, and by CmaxThe points of corresponding coded sequence, as the down-sampled points N of reality in the single symbol '. With Cmax=C2Exemplified by, C2Corresponding 2nd group of coded sequence, the 2nd group of coded sequence S1 2、S2 2 S3 2And S4 2Sampling number be 7, Then can determine that the down-sampled points N of reality in single symbol ' it is 7.
It is corresponding to signal from transmitting terminal second down-sampled respectively according to 2K+1 groups coded sequence in the present embodiment Lead code in signal carries out correlation computations, to obtain 2K+1 lead code correlated results, and it is related based on 2K+1 lead code As a result the down-sampled points of reality being calculated in single symbol, correlation is carried out relative to each code element is directed in the prior art The technical solution of calculating, the technical solution of this example greatly reduces the consumption of the hardware such as multiplier in correlation computations, and estimates Actual down-sampled points are time-consuming short, improve the timeliness of symbol synchronization.
Optionally, in the above-mentioned or following embodiment of the application, according to 2K+1 groups coded sequence respectively to lead code into Row correlation computations can be that slip correlation computations are carried out to lead code, i.e., to every group of coded sequence in 2K+1 group coded sequences Repeatedly slided in lead code using corresponding points as length of window, so as to calculate multiple correlation calculation results.Its In, it is one and the relevant empirical values of N to slide number, it usually needs slip [N/4] is secondary respectively to the left and to the right, slides altogether [N/2] is secondary, wherein [] represents bracket function.By taking first symbol in lead code as an example, every group of coded sequence can be first It is secondary that [N/2] is slided in a symbol.Often slide once, a correlated results is calculated, to obtain [N/2]+1 correlation computations knot Fruit, and correlated results of the maximum as first symbol is obtained from [N/2]+1 correlation calculation result.
For example, the sampled point in first symbol is X1=[x1x2x3x4x5x6x7x8x9], it is corresponding with first symbol Coded sequence S1 1Exemplified by, S1 1=[1,1,1,1,1,1,1,1,1].N=9, then it is [9/4]=2 to slide number, respectively with Xm's First point x1Centered on, slide once and to the right slide once to the left.
When carrying out slip correlation computations, S can be calculated first1 1When not sliding and X1 sums correlation calculation result, that is, From S1 1In the 1st point start to do correlation computations with the point in X1 successively.Then, by S1 1Slide once to the left, that is, from S1 1In the 2nd point start to do correlation computations with the point in X1 successively.Finally, by S1 1Slide once to the right, that is, from X1 In the 2nd point start successively with S1 1In point do correlation computations.Above-mentioned correlation computations three times can respectively obtain a related knot Fruit, can choose correlated results of the value of maximum as first symbol from these three results.And then by using slip Coded sequence, improves the reasonability of the actual point in the single symbol estimated.
Optionally, in the above-mentioned or following embodiment of the application, lead code is carried out by taking first group of coded sequence as an example During correlation computations, in addition to Fig. 4 c illustrated embodiments, it can also be closed according to the content and Coding conversion state chart of lead code System, the corresponding coded sequence of each code element in lead code is combined, obtains the corresponding first coded sequence group of lead code Close.For example, by taking the lead code 1010v1 of FM0 as an example, accorded with without considering breaking rules, then visual lead code is 10101.According to Fig. 1 e institutes The Coding conversion state chart relation shown, it can be S that can obtain corresponding first coding sequence combination of lead code 101011 1 S3 1 S4 1 S2 1 S1 1.Then, lead code the first coding sequence combination corresponding with lead code is subjected to correlation computations, so that directly To the lead code correlated results of first group of coded sequence.
When carrying out correlation computations to lead code using other groups of coded sequences, can sample similar approach obtain it is leading Code corresponding second coding sequence combination, the 3rd coding sequence combination ... and 2K+1 coding sequence combinations.Then, will Lead code other coding sequence combinations corresponding with lead code carry out correlation computations, so as to directly obtain other groups of coded sequences Lead code correlated results.
What deserves to be explained is when lead code some coding sequence combination corresponding with lead code is carried out correlation computations Slip correlation computations can also be carried out, the principle for sliding correlation computations can be found in previous embodiment, and it is not described here in detail.
In embodiment shown in above-mentioned Fig. 4 a, the actual samples calculated before symbol synchronization in single symbol are described The process of points.During practical communication, the clock jitter of transmitting terminal is probably variation, and then is caused in single symbol Actual down-sampled points meeting respective change, in this case, can be in code to be further ensured that the accuracy of symbol synchronization The actual point in single symbol is calculated during first synchronization in real time.Embodiment shown in Fig. 5 provides a kind of symbol synchronization side Method, the symbol synchronization method include the process for calculating the down-sampled points of reality in single symbol in real time.As shown in figure 5, the party Method includes：
Step 501, with local clock frequency to from transmitting terminal signal carry out over-sampling processing, to obtain over-sampling Signal.
Step 502, with frequency N × fT0Down-sampled processing is carried out to the oversampled signals, to obtain down-sampled signal, N It is positive integer, fT0It is the desired signal frequencies of the transmitting terminal.
Step 503, according to 2K+1 groups coded sequence respectively in the down-sampled signal lead code carry out correlometer Calculate, to obtain 2K+1 lead code correlated results；Wherein, the encoding state that each coded sequence represents in 2K+1 groups coded sequence The coding mode used by transmitting terminal determines that the points of coded sequence are one, i=0 in N ± i in every group of coded sequence, 1,2 ... K, K are nonnegative integers, and the size of K is related to N.
Step 504, obtain the corresponding coding of lead code correlated results maximum in the 2K+1 lead code correlated results The points of sequence, as the down-sampled points of reality in the signal of transmitting terminal in single symbol.
Step 505, according to the down-sampled points of reality in the single symbol, edge is carried out to the down-sampled signal Detection, to determine the first sampling point of each code element in the down-sampled signal.
The description of each step can be found in the description of corresponding steps in previous embodiment in the present embodiment, and details are not described herein.
In the present embodiment, receiving terminal carries out the signal progress over-sampling from receiving terminal down-sampled again, uses afterwards 2K+1 groups coded sequence carries out correlation computations to down-sampled signal and obtains the actual drop in the signal from sending end in single symbol Sampling number, then identifies each code element in down-sampled signal based on actual samples points and with reference to Edge check First sampling point, to realize symbol synchronization.
In most circumstances, the clock jitter of transmitting terminal is a fixed value, therefore in particular time range, is sent The code check of the signal of the transmission at end is fixed.That is the meter that step 503 and step 504 describe in embodiment illustrated in fig. 5 Calculating the operation of the down-sampled points of reality in single symbol can perform once for some signal that transmitting terminal is sent, follow-up logical The down-sampled points of reality that letter process can be continued to use in the single symbol calculated carry out symbol synchronization.Using such reality Mode is applied, can further reduce consuming of the symbol synchronization to hardware source.
For some special circumstances, the clock jitter of transmitting terminal is probably variation, then the actual drop in single symbol is adopted Number of samples can respective change.At these in special circumstances, it may be necessary to all go to perform in intermittent or each element synchronization The operation for the down-sampled points of reality in the single symbol of calculating that step 503 and step 504 describe in embodiment illustrated in fig. 5.Its In, for the actual drop calculated in single symbol that step 503 and step 504 describe in embodiment illustrated in fig. 5 need not be performed The element synchronization of the operation of sampling number can be found in Fig. 2-embodiment illustrated in fig. 4.
Fig. 6 a are the structure diagrams of symbol synchronization device provided by the embodiments of the present application.As shown in Figure 6 a, the device Including：
Over-sampling module 601, over-sampling processing is carried out with local clock frequency to the current demand signal from transmitting terminal, with Obtain the first oversampled signals.
Down-sampled module 602, with frequency N × fT0Down-sampled processing is carried out to first oversampled signals, to obtain the One down-sampled signal, N are positive integers, fT0It is the desired signal frequencies of the transmitting terminal.
Edge check module 603, according to the down-sampled point of the reality in the signal from the transmitting terminal in single symbol Number, carries out Edge check, to determine the sampling of each code element in the first down-sampled signal to the described first down-sampled signal Starting point.
Still optionally further, as shown in Figure 6 b, described device further includes：Correlation computations module 604 and points acquisition module 605。
Over-sampling module 601, is additionally operable to：With local clock frequency to the signal before the current demand signal of transmitting terminal Over-sampling processing is carried out, to obtain the second oversampled signals.Down-sampled module 602 is additionally operable to frequency N × fT0To described second Oversampled signals carry out down-sampled processing, to obtain the second down-sampled signal.Correlation computations module 604, for according to 2K+1 groups Coded sequence carries out correlation computations to the lead code in the described second down-sampled signal respectively, to obtain 2K+1 lead code phase Close result.Points acquisition module 605 is used to obtain lead code correlated results maximum in the 2K+1 lead code correlated results The points of corresponding coded sequence, as the down-sampled points of reality in the single symbol.Wherein, coded sequence in every group The encoding state of expression is determined that the points of coded sequence are in N ± i in every group by the coding mode that the transmitting terminal uses One, i=0,1,2 ... K, K is nonnegative integer, and the size of K is related to N.
Still optionally further, the correlation computations module 604 is additionally operable to, according to first group of coded sequence to described Lead code in second down-sampled signal carries out slip correlation computations, corresponding leading to obtain first group of coded sequence Code correlated results.
Still optionally further, the correlation computations module 604 is specifically used for, according to the encoding state of the coding mode Transformational relation, selection and the matched coded sequence of each code element of the lead code from first group of coded sequence；Utilize Correlation computations are carried out to each code element of the lead code with each code element matched coded sequence of the lead code, to obtain Obtain the correlated results of each code element of the lead code；The correlated results of each code element of the lead code is added up, with Obtain the corresponding lead code correlated results of first group of coded sequence.
Still optionally further, the Edge check module 603 is specifically used for：Reality on the single symbol is obtained After down-sampled points, according to the down-sampled points of reality in the single symbol, side is carried out to the described second down-sampled signal Along detection, to determine the first sampling point of each code element in the second down-sampled signal.
Still optionally further, the signal before the current demand signal is directed to the first of receiving terminal return for the transmitting terminal A answer signal.
Still optionally further, the coding mode is orthogonal coding mode.
Still optionally further, the Edge check module 603 is specifically used for：According to the first sampling point of previous symbol and The down-sampled points of reality in the single symbol, determine current symbol estimates starting point；From it is described estimate starting point and In its several front and rear sampled point, obtain and the absolute value of the difference of continuous L sampled point is all higher than the sampling of given threshold afterwards Point is used as edge point, and L is positive integer；According to the edge point, the first sampling point of the current symbol is determined.
Symbol synchronization device provided in this embodiment, by down-sampled processing, and combines single in the signal from transmitting terminal Symbol synchronization, is converted to the judgement of sampling number, reduces the realization of symbol synchronization by the down-sampled points of reality in a symbol Difficulty, further combined with Edge check, can make the points surplus of each code element not accumulate next symbol as far as possible, so that more Add the first sampling point for accurately determining each code element, ensure the precision of symbol synchronization.
It should be noted that in the corresponding embodiments of Fig. 6 a and Fig. 6 b, the function performed by each module can be by each Kind of application specific integrated circuit (ASIC), digital signal processor (DSP), digital signal processing appts (DSPD), programmable patrol Device (PLD), field programmable gate array (FPGA), micro- middle control element, microprocessor or the realization of other electronic components are collected, no Repeat again.
The built-in function and structure of symbol synchronization device are the foregoing described, as shown in fig. 7, in practice, symbol synchronization dress Put and can be achieved as symbol synchronization equipment, including：Memory 701, processor 702 and communication component 703.
Wherein, memory 701 is used for：One or more computer instruction is stored, and can be configured as storing other various Data are to support the operation in symbol synchronization equipment.The example of these data includes being used to operate in symbol synchronization equipment Any application program or method instruction.
Memory 701 can realize by any kind of volatibility or non-volatile memory device or combinations thereof, Such as static RAM (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable is read-only Memory (EPROM), programmable read only memory (PROM), read-only storage (ROM), magnetic memory, flash memory, magnetic Disk or CD.
Processor 702, couples with memory 701, for performing the computer instruction in memory 701, for：With Local clock frequency carries out over-sampling processing to the current demand signal from transmitting terminal, to obtain the first oversampled signals；With frequency N×fT0Down-sampled processing is carried out to first oversampled signals, to obtain the first down-sampled signal, N is positive integer, fT0It is The desired signal frequencies of the transmitting terminal；According to the down-sampled point of the reality in the signal from the transmitting terminal in single symbol Number, carries out Edge check, to determine the sampling of each code element in the first down-sampled signal to the described first down-sampled signal Starting point.
Still optionally further, processor 702 is specifically used for：With local clock frequency to the current demand signal from transmitting terminal Signal before carries out over-sampling processing, to obtain the second oversampled signals；With frequency N × fT0To second oversampled signals Down-sampled processing is carried out, to obtain the second down-sampled signal；According to 2K+1 groups coded sequence respectively to the described second down-sampled letter Lead code in number carries out correlation computations, to obtain 2K+1 lead code correlated results；It is related to obtain the 2K+1 lead code As a result the points of the middle maximum corresponding coded sequence of lead code correlated results, are adopted as the actual drop in the single symbol Number of samples.Wherein, the encoding state that coded sequence represents in every group determines by the coding mode that the transmitting terminal uses, every group It is nonnegative integer that the points of middle coded sequence, which are one, i=0,1,2 ... K, K in N ± i, and the size of K is related to N.
Still optionally further, processor 702 is additionally operable to, down-sampled to described second according to first group of coded sequence Lead code in signal carries out slip correlation computations, to obtain the corresponding lead code correlated results of first group of coded sequence.
Still optionally further, processor 702 is specifically used for, according to the Coding conversion state chart relation of the coding mode, from Selection and the matched coded sequence of each code element of the lead code in first group of coded sequence；Using with it is described leading The matched coded sequence of each code element of code carries out correlation computations to each code element of the lead code, described leading to obtain The correlated results of each code element of code；The correlated results of each code element of the lead code is added up, to obtain described The corresponding lead code correlated results of one group of coded sequence.
Still optionally further, processor 702 is specifically used for：The down-sampled points of reality on the single symbol is obtained Afterwards, according to the down-sampled points of reality in the single symbol, Edge check is carried out to the described second down-sampled signal, with Determine the first sampling point of each code element in the described second down-sampled signal.
Still optionally further, the signal before the current demand signal is directed to the first of receiving terminal return for the transmitting terminal A answer signal.
Still optionally further, the coding mode is orthogonal coding mode.
Still optionally further, processor 702 is specifically used for：According to the first sampling point of previous symbol and the single code The down-sampled points of reality in member, determine current symbol estimates starting point；Starting point is estimated from described and it is front and rear some In a sampled point, obtain and the absolute value of the difference of continuous L sampled point is all higher than the sampled point of given threshold as edge afterwards Point, L are positive integers；According to the edge point, the first sampling point of the current symbol is determined.
Wherein, it is wired or wireless between equipment and other equipment where communication component 703 is configured to facilitate communication component The communication of mode.Equipment where communication component can access the wireless network based on communication standard, such as WiFi, 2G or 3G, or it Combination.In one exemplary embodiment, communication component is received from external broadcasting management system via broadcast channel Broadcast singal or broadcast related information.In one exemplary embodiment, the communication component further includes near-field communication (NFC) Module, to promote junction service.For example, radio frequency identification (RFID) technology, Infrared Data Association can be based in NFC module (IrDA) technology, ultra wide band (UWB) technology, bluetooth (BT) technology and other technologies are realized.
Further, as shown in fig. 7, the symbol synchronization equipment further includes：Display 704, power supply module 705, audio component Other components such as 706.Members are only schematically provided in Fig. 7, are not meant to that symbol synchronization equipment is only included shown in Fig. 7 Component.
Wherein, display 704 includes screen, its screen can include liquid crystal display (LCD) and touch panel (TP). If screen includes touch panel, screen may be implemented as touch-screen, to receive input signal from the user.Touch surface Plate includes one or more touch sensors to sense the gesture on touch, slip and touch panel.The touch sensor can Not only to sense the boundary of a touch or slide action, but also detect and the touch or slide relevant duration And pressure.
Wherein, power supply module 705, the various assemblies of equipment provide electric power where power supply module.Power supply module can wrap Include power-supply management system, one or more power supplys, and other and equipment generation, management and distribution electric power where power supply module Associated component.
Wherein, audio component 706, can be configured as output and/or input audio signal.For example, audio component includes one A microphone (MIC), the equipment where audio component is in operator scheme, such as call model, logging mode and speech recognition mould During formula, microphone is configured as receiving external audio signal.The received audio signal can be further stored in memory Or sent via communication component.In certain embodiments, audio component further includes a loudspeaker, for exports audio signal. Symbol synchronization equipment provided in this embodiment, by down-sampled processing, and combines in the signal from transmitting terminal in single symbol The down-sampled points of reality, symbol synchronization is converted to the judgement of sampling number, reduce symbol synchronization realizes difficulty, into One step combination Edge check, can make the points surplus of each code element not accumulate next symbol as far as possible, so that more accurately Determine the first sampling point of each code element, ensure the precision of symbol synchronization.
Correspondingly, the embodiment of the present application also provides a kind of computer-readable recording medium for being stored with computer program, meter Calculation machine program is performed each step that can be realized and can be performed in above method embodiment by symbol synchronization equipment.
Finally it should be noted that：The above embodiments are merely illustrative of the technical solutions of the present invention, rather than its limitations；To the greatest extent Pipe is with reference to the foregoing embodiments described in detail the present invention, it will be understood by those of ordinary skill in the art that：It is still It can modify to the technical solution described in foregoing embodiments, or which part technical characteristic is equally replaced Change；And these modifications or replacement, the essence of appropriate technical solution is departed from the essence of various embodiments of the present invention technical solution God and scope.

Claims (12)

  1. A kind of 1. symbol synchronization method, it is characterised in that including：
    Over-sampling processing is carried out to the current demand signal from transmitting terminal with local clock frequency, to obtain the first oversampled signals；
    With frequency N × fT0Down-sampled processing is carried out to first oversampled signals, to obtain the first down-sampled signal, N is just Integer, fT0It is the desired signal frequencies of the transmitting terminal；
    According to the down-sampled points of reality in the signal from the transmitting terminal in single symbol, to the described first down-sampled signal Edge check is carried out, to determine the first sampling point of each code element in the first down-sampled signal.
  2. 2. according to the method described in claim 1, it is characterized in that, according to single symbol in the signal from the transmitting terminal On the down-sampled points of reality, Edge check is carried out to the described first down-sampled signal, to determine the first down-sampled signal Before the first sampling point of middle each code element, further include：
    Over-sampling processing is carried out to the signal before the current demand signal of transmitting terminal with local clock frequency, to obtain the second mistake Sampled signal；
    With frequency N × fT0Down-sampled processing is carried out to second oversampled signals, to obtain the second down-sampled signal；
    Correlation computations are carried out to the lead code in the described second down-sampled signal according to 2K+1 groups coded sequence respectively, to obtain 2K + 1 lead code correlated results；
    The points of the corresponding coded sequence of lead code correlated results maximum in the 2K+1 lead code correlated results are obtained, are made For the down-sampled points of reality in the single symbol；
    Wherein, the encoding state that each coded sequence represents in 2K+1 groups coded sequence is true by the coding mode that the transmitting terminal uses Fixed, it is nonnegative integer that the points of coded sequence, which are one, i=0,1,2 ... K, K in N ± i, in every group of coded sequence, and K's is big It is small related to N.
  3. 3. according to the method described in claim 2, it is characterized in that, to first group of code sequence in the 2K+1 groups coded sequence For row, correlation computations are carried out to the lead code in the described second down-sampled signal according to first group of coded sequence, with To the corresponding lead code correlated results of first group of coded sequence, including：
    Slip correlation computations are carried out to the lead code in the described second down-sampled signal according to first group of coded sequence, with To the corresponding lead code correlated results of first group of coded sequence.
  4. 4. according to the method described in claim 2, it is characterized in that, to first group of code sequence in the 2K+1 groups coded sequence For row, correlation computations are carried out to the lead code in the described second down-sampled signal according to first group of coded sequence, with To the corresponding lead code correlated results of first group of coded sequence, including：
    According to the Coding conversion state chart relation of the coding mode, selection and the lead code from first group of coded sequence The matched coded sequence of each code element；
    Correlometer is carried out to each code element of the lead code using with each code element of the lead code matched coded sequence Calculate, to obtain the correlated results of each code element of the lead code；
    The correlated results of each code element of the lead code is added up, with obtain first group of coded sequence it is corresponding before Leading code correlated results.
  5. 5. according to the method described in claim 2, it is characterized in that, down-sampled points of reality on the single symbol is obtained Afterwards, the method further includes：
    According to the down-sampled points of reality in the single symbol, Edge check is carried out to the described second down-sampled signal, with true The first sampling point of each code element in the fixed second down-sampled signal.
  6. 6. according to the method described in claim 2, it is characterized in that, the signal before the current demand signal is the transmitting terminal pin First answer signal returned to receiving terminal.
  7. 7. according to the method any one of claim 2-6, it is characterised in that the coding mode is orthogonal coding side Formula.
  8. 8. according to the method any one of claim 1-6, it is characterised in that down-sampled according to the reality in single symbol Points, Edge check is carried out to the described first down-sampled signal, to determine adopting for each code element in the first down-sampled signal Sample starting point, including：
    According to the down-sampled points of reality on the first sampling point of previous symbol and the single symbol, the pre- of current symbol is determined Estimate starting point；
    Estimated from described in starting point and its several front and rear sampled point, obtain and the difference of continuous L sampled point afterwards it is exhausted It is positive integer that the sampled point of given threshold is all higher than to value as edge point, L；
    According to the edge point, the first sampling point of the current symbol is determined.
  9. A kind of 9. symbol synchronization device, it is characterised in that including：
    Over-sampling module, for carrying out over-sampling processing to the current demand signal from transmitting terminal with local clock frequency, to obtain First oversampled signals；
    Down-sampled module, for frequency N × fT0Down-sampled processing is carried out to first oversampled signals, to obtain the first drop Sampled signal, N are positive integers, fT0It is the desired signal frequencies of the transmitting terminal；
    Edge check module is right for the down-sampled points of reality in single symbol in signal of the basis from the transmitting terminal The first down-sampled signal carries out Edge check, to determine that the sampling of each code element in the first down-sampled signal originates Point.
  10. 10. device according to claim 9, it is characterised in that further include：Correlation computations module and points acquisition module；
    The over-sampling module, is additionally operable to carry out the signal before the current demand signal of transmitting terminal with local clock frequency Sampling processing, to obtain the second oversampled signals；
    The down-sampled module, is additionally operable to frequency N × fT0Down-sampled processing is carried out to second oversampled signals, to obtain Second down-sampled signal；
    The correlation computations module, for according to 2K+1 groups coded sequence respectively to the lead code in the described second down-sampled signal Correlation computations are carried out, to obtain 2K+1 lead code correlated results；
    The points acquisition module, for obtaining lead code correlated results pair maximum in the 2K+1 lead code correlated results The points for the coded sequence answered, as the down-sampled points of reality in the single symbol；
    Wherein, the encoding state that each coded sequence represents in 2K+1 groups coded sequence is true by the coding mode that the transmitting terminal uses Fixed, it is nonnegative integer that the points of coded sequence, which are one, i=0,1,2 ... K, K in N ± i, in every group of coded sequence, and K's is big It is small related to N.
  11. A kind of 11. symbol synchronization equipment, it is characterised in that including：Memory and processor；
    The memory is used for：Store one or more computer instruction；
    The processor is used to perform one or more computer instruction, for：
    Over-sampling processing is carried out to the current demand signal from transmitting terminal with local clock frequency, to obtain the first oversampled signals；
    With frequency N × fT0Down-sampled processing is carried out to first oversampled signals, to obtain the first down-sampled signal, N is just Integer, fT0It is the desired signal frequencies of the transmitting terminal；
    According to the down-sampled points of reality in the signal from the transmitting terminal in single symbol, to the described first down-sampled signal Edge check is carried out, to determine the first sampling point of each code element in the first down-sampled signal.
  12. 12. a kind of computer-readable recording medium for being stored with computer program, it is characterised in that the computer program is held The step in the method any one of claim 1-8 can be realized during row.
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