CN85102959A - The code division multiplexing unit that adopts Direct Sequence Spread Spectrum Signal to handle - Google Patents

Abstract

Some synchronous transmitters on common clock, one of every emission by appointment but the public bipolarity pseudo noise code institute expanded data signal of sign indicating number sequence displacement all inequality.A receiver that is synchronized to this clock, can give fixed transmitter signal to one distinguishes from other transmitter signal, method is to produce one first pseudo noise code, it is duplicating of this public bipolarity pseudo noise code and has and sign indicating number sequence displacement that the sign indicating number sequence bit phase shift of predetermined transmitter is worked as, and producing one second bipolarity pseudo noise code, it is duplicating of this public bipolarity pseudo noise code and has a sign indicating number sequence displacement of not specifying.The difference of the first and second bipolarity pseudo-random code sequences is ternary sign indicating number sequences, and it and the signal of coming in are carried out cross-correlation.

Description

The code division multiplexing unit that adopts Direct Sequence Spread Spectrum Signal to handle

The present invention is usually relevant with the code division multiplexing of adopting Direct Sequence Spread Spectrum Signal to handle, more specifically, is the signal processing that is used for increasing the multichannel transmitter number under given code length.

In a spread spectrum system, transmitting is expanded on a frequency range, and this section frequency range is much wideer than launching the required minimum frequency range of this customizing messages.In other modulation format, resemble amplitude modulation or frequency modulation, the bandwidth comparability of transmission bandwidth and information itself is intended, and a spread spectrum system is for example having only several kilo hertzs inromation bandwidth to modulate with the code signal in a broadband, this information expansion being had on the wide frequency band of several megahertzes at one.Therefore, a key character of difference spread spectrum system and other wideband transmission system is, in the spread-spectrum signal processing, this signal that is sent out that has been different from the signal extension that transmits information arranged.

In typical spread spectrum system, the expansion that transmits is with following method: the modulation of (1) direct sequence, (2) frequency hopping or (3) pulse-frequency modulation or " linear frequency modulation " modulation.In the direct sequence modulation, carrier wave is modulated by a digital coding sequence, and the bit rate of coded sequence is far above the signal bandwidth of information.Frequency hopping is that carrier frequency is come saltus step by the pattern of coded sequence domination with discrete increment, and in the Linear Frequency Modulation system, carrier frequency is inswept one section wide frequency band in the burst length of being given.Other but the carrier frequency expansion technique that is of little use comprise that the time goes up and jump frequency hopping when sending out and jumping, jump sending out on time is to be controlled by a coded sequence launch time (normally low duty cycle and short duration), and frequency hopping then is that a coded sequence not only determines tranmitting frequency but also determine launch time during jumping.

Spread spectrum system has various application, mainly is to make the earwig not translate the information transmitted sign indicating number come.Other application comprise navigation and range finding, and resolution wherein is decided by used specific bit rate and sequence length.(spread spectrum system) book can be for referencial use for R.C.Dixon work " Spread Spectrum System ".This book John Wiley in 1976 ﹠amp; Sons.N.Y. publish, particularly the 9th chapter has detailed narration about application.

Direct sequence modulation involves a carrier frequency and is modulated by the coded sequence of any form of several different-formats (for example amplitude modulation or frequency modulation), yet the quarter-phase phase shift keying is the most frequently used a kind of.In quarter-phase phase shift keying (PSK), two inputs of balanced mixer are coded sequence and radio-frequency carrier, when making the emission carrier wave when " 1 ", coded sequence has the first phase shift X °, when coded sequence makes it to have second phase shift (180+X) ° during for " 0 ".Other form of quarter-phase phase shift keying modulation ratio is superior, and this is because carrier wave is suppressed in the transmission, receives with common equipment is difficult, and in transmission, with respect to carrier wave, has kept more power on information.In the 4th chapter of above-mentioned Dixon book, provided the characteristic of quarter-phase phase shift keying.

Be used for expanding the coding form of transmission bandwidth, general desirable linear code is so when especially the fail safe of message not being required, and the maximum code of getting best their cross correlation.According to definition, maximum code is exactly the longest sign indicating number that can be produced by a given shift register or other delay element that certain-length is arranged.In two condition shift-register sequence generator, maximum length (the being abbreviated as ML) sequence that is produced by n level shift register is (2 ⁿ-1) position.Shift-register sequence generator is made up of through the shift register that feeds back to other grade and go some shift register stage by one.Output code flow is decided by the mode of the sum of series feedback of shift register duplicating length before the sequence.For example one 5 grades shift register may produce 31 two-state sequences (promptly 2 ⁵-1) its maximum length that, Here it is (ML) sequence.The ML sequence that the shift register ML sequencer that progression is very many is produced, repeat so often so that this sequence look like and be to have characteristics of noise and to be difficult to and to detect at random.Therefore, direct sequency system is called " pseudo noise " system sometimes.

In book 3.1 joints of Dixon, summed up the character of maximal sequence, listed feedback method of attachment in Dixon book 3.6 tables by 3 to 100 grades of maximum code generators.For one 1023 sign indicating number, be equivalent to 10 grades of shift registers that have with the maximum length feedback, it has 512 " 1 " and 511 " 0 ", differs one.The relative position of these " 1 " and " 0 " changes in ML sign indicating number sequence, and for identical ML length sequences, the number of the number of " 1 " and " 0 " all is a fixed number in each maximal-length sequence.

Because the difference of the number of the number of " 1 " and " 0 " always one in any maximal-length sequence, so auto-correlation of a maximum linear sign indicating number, promptly the replica code of this sequence with displacement back itself gone many to compare, remove at 0+1 position phase-shifted region, its value all is-1, and in this zone, auto-correlation changes to (2 linearly from-1 ⁿ-1).Therefore, for one 1023 maximum code (2 ⁿ-1), the peak of auto-correlation function-to a mean value be 1024, be converted into 30.1db.

This characteristic can be used in the code division multiplexing direct sequence spread spectrum transmission just.Many receivers of putting in the different displacements of public ML sign indicating number only could be synchronously to the transmitter with the same displacement of this common code.Therefore, can not have at one time with same frequency and launch a plurality of signals faintly.In the multiloop loop system of auto-correlation type, a public clock or timing source are arranged, many transmitters and at least one receiver are all synchronous to it.These transmitters produce a public maximal-length sequence, but the sign indicating number of every transmitter compares with the sign indicating number of other transmitter, at least displacement one.The receiver machine produces a replica code the same with the maximal-length sequence of common issue in this locality, and its sign indicating number sequence bit is moved the displacement that is equivalent to certain tuning with it particular transmitter.The local sequence that produces with receive the signal that comes and in correlation detector, carry out auto-correlation, this detector is adjusted to such an extent that can recognize and have only+level and the only information extraction from the signal that fixed in advance transmitter produces of the difference of 1 bit synchronization.

Because the autocorrelation performance of maximum-length code sequence has an inclined to one side value that is equivalent to the code length inverse, promptly

V/（2 ⁿ-1）

Wherein V is the voltage amplitude that is equivalent to " 1 ", and n is the progression of shift register, occurs overlapping between adjacent channel.Therefore, for unwanted entering signal, can not reject fully.So the non-fuzzy signal differentiates and just requires to place a shield segment at interchannel that this has just reduced the number of potential transmitter to certain code length.Though a long maximal-length sequence can compensate this section protection to increase the number of potential transmitter, it makes the power imbalance problem that slows down synchronously and produce multichannel transmitter.

Therefore, a main purpose of the present invention provides a kind of multiplex method and system of auto-correlation type code division of improvement, wherein can not have under certain code length and differentiates the more transmitter of more number faintly.Another purpose provides the multiplex method and system of a kind of code division, and it adopts short ML sign indicating number to remove to differentiate the transmitter of quite a lot of number.

Another object of the present invention provides a kind of correlation detector that is used for the improvement of input.

Another purpose provides a kind of correlation detector that is used to detect the improvement of code division multiplex system signal.

Another purpose provides a kind of correlation detector that is used for the improvement of direct sequence spread spectrum code division multiloop loop system.

There is a purpose to provide a kind of the demarcation again and adjusts the correlation detector circuit of number for minimum.

There is a purpose to provide a kind of the demarcation again and adjusts number and be minimum correlation detector, be used in the degree of correlation that decides in the multi-channel detector in the code division multiplex communication between a receiver and the transmitter of reserving in advance.

Another object of the present invention is to improve the ratio of making an uproar in a code division multiplexing receiver.Another purpose is to improve signal to noise ratio and synchronous characteristic in a code division multiplexing receiver, this receiver has several correlation detectors, the latter regularly postpones in the different in succession sign indicating number displacement of public pseudo noise code, and output is handled to determine best receiver synchronous.

Another object of the present invention be improve in the Receiver of Direct-sequence Spread Spectrum synchronously.Also having a purpose is improve receiver in the following receiver of direct sequence spread spectrum synchronous, and this receiver adopts a plurality of correlation detectors, and they are the equal part sign indicating number position of displacement each other, so that the synchronization delay of discriminating the best.

Another purpose is to remove signal and the noise differentiated in Receiver of Direct-sequence Spread Spectrum.

It is improve receiver in Receiver of Direct-sequence Spread Spectrum when data sampling rate is higher than timing signal frequency synchronous that a purpose is arranged again.

The method according to this invention and system, more than these and other purpose can both satisfy, some transmitters and at least one receiver are wherein arranged all synchronously on a common timing signal source, every transmitter sends the carrier wave of a data modulation, this carrier wave is expanded by a bipolarity pseudo noise code, and this pseudo noise code is a given public bipolar code sequence that different displacements are arranged.In order to differentiate that the signal that a fixed in advance transmitter is sent out distinguishes it from other transmitter signals, receiver produces the bipolarity pseudo noise code of two this locality, and they all are the replica codes of the public bipolarity pseudo noise code of emission.One of them local code has and the fixed in advance given same sign indicating number sequence displacement of sign indicating number sequence displacement of transmitter, and another local sign indicating number that produces then has never gives the sign indicating number sequence displacement of appearing.These two the local sign indicating numbers that produce can draw a ternary sign indicating number sequence through handling, and it and the signal of coming in are carried out cross-correlation, are used for differentiating and information extraction from the coding that fixed in advance transmitter is sent out.

According to a further aspect in the invention, this two condition coded sequence also can be maximum length (ML) sequence with good automatic correlative property.Utilize the modulation of phase shift keying (PSK) signal, information can be embedded in the two condition coded sequence.

According to a further aspect in the invention, can provide the many different concrete device of correlation detector, wherein first and second reference signals with two condition Serial No. form multiply each other with the modulated data bipolar sequence of coming in, and make two products subtract each other again.Difference is carried out integration random noise is on average fallen, and further demodulation is to recover two condition information.The next transfer function of each channel derivation by correlation detector is

1/(T) ${\∫}_0^T$ s（t）〔r（t）-e（t）〕dt

R(t wherein) being to have the bipolar sequence that is equivalent to fixed in advance transmitter code displacement, is to have never to be appeared the bipolar code sequence of yard displacement e(t), s(t) is the signal of coming in, and T is one yard bit period.

According to a kind of concrete device of coherent detection, the multiplier of each channel or slave receiver is made up of an analog multiplexer, its two inputs each by two suitable reference sequences r(t) and e(t) control.This multiplexer adds list entries s(t selectively) and list entries be inverted to a subtracter, provide one and be equivalent to expression formula s(t) (r(t)-e(t)) and will be in the sequence of one yard bit period upper integral, this just produces relevant.

In second kind of concrete device of correlation detector, N channel correlation detector is made up of the analog multiplexer of three inputs by N, corresponding to the polarity of two reference sequences, just input signal s(t), input signal s(t) anti-phase or zero be added to integration and remove and make in the circuit in several yards bit period upper integrals in succession.Two reference signal r(t) and e(t) be the multiplexer of controlling this three input by Digital Logical Circuits.

According to the third concrete device of correlation detector, all signal processing are undertaken by digital form entirely.The signal s(t that receives) be digitized, and the cycle that equals one yard bit period with the time in an accumulator is carried out the algebraically summation.The difference of initial value and stop value is represented s(t in the accumulator) integrated value on one yard bit period.When the value of two reference signals equated, the value of accumulator remained unchanged.When two reference signals were unequal, the content in the accumulator was by s(t) value make amendment: as r(t) when being one " 1 ", s(t) value after the digitlization is added in the accumulator; As r(t) when being one " 0 ", s(t) value after the digitlization is by being cut in the accumulator.

According to a kind of distortion of this third concrete device, voltage to frequency changer the input signal digitlization, and with a frequency counter go to add up this and several.When two reference signals equated, a clock of actuation counter was under an embargo.As r(t) when being " 1 ", this binary counter is the s(t that is controlled to by next with Voltage-to-frequency Converter) proportional speed summation pulse.As r(t) when being " 0 ", accumulative total is subtraction, counting direction is anti-.

According to a further aspect in the invention, can provide at some transmitters and at least one receiver and all be synchronized to a kind of method and system that improves signal to noise ratio in this Resistant DS Spread Spectrum System of a common timing signal source.Every transmitter is sent out an expanded data signal by the bipolarity pseudo noise code, this pseudo noise code be one have an appointment but public bipolar code sequences of different displacements all.Receiver is made up of several correlation detectors, and each produces the bipolarity pseudo noise code of two this locality, and the latter is the duplicating of public polarity pseudo noise code of emission.One of them local sign indicating number that produces has the sign indicating number sequence displacement same sign indicating number sequence displacement given with intended transmitter, the sign indicating number sequence displacement of another local generation yard then with arbitrary transmitter give all inequality.These two the local sign indicating numbers that produce are handled in each correlation detector, can draw a ternary sign indicating number sequence, the latter carries out cross-correlation with the signal of coming in, produce some coherent signals, they can be used for adjusting the timing of receiver, make each correlation detector position on a local relevant peaks.According to the present invention, except the synchronous of receiver is provided, the output of these correlation detectors is processed again to be received data and makes signal to noise ratio become the best.When the receiver quilt is well synchronous, recognize the symbol of the symbol of each relevant peaks corresponding to the data that sending, these relevant outputs are also handled with weighted factors that some are selected according to the certain distortion of existence, make signal to noise ratio become the best.

According to a further aspect in the invention, provide a kind of synchronous method and system between a transmitter and the receiver that can improve in the direct sequence spread spectrum code division multiplex system, particularly some transmitters wherein and at least one receiver are all synchronously on a common timing signal source.One of every transmitter emission is by bipolarity pseudo noise code institute expanded data signal, this pseudo noise code be one have an appointment but public bipolar code sequences of displacement inequality all.Receiver is made up of a plurality of correlation detectors, and each produces the bipolarity pseudo noise code of two this locality, and the latter is the duplicating of public bipolarity pseudo noise code of emission.One of them local sign indicating number that produces has the sign indicating number sequence displacement same sign indicating number sequence displacement given with intended transmitter, the sign indicating number sequence displacement of another local generation yard then with arbitrary transmitter give all inequality.After these two local generation sign indicating numbers are processed, draw a ternary sign indicating number sequence, the latter carries out cross-correlation with the signal of coming in, with discriminating and information extraction the signal of sending out from fixed in advance transmitter.When this receiver with fixed transmitter is on time in advance, cross-correlation produces an in-phase signal, Here it is greatly, and the signal that produces 90 ° of phase places, it is minimum that Here it is.Adjust the timing of receiver, make the cross-correlated signal of 90 ° of phase places become minimum, just can provide synchronous.

According to a kind of concrete device of the present invention, can measure the ratio of in-phase signal and 90 ° of phase signals, this ratio is processed to come the regularly size of displacement of receiver control, draws synchronously completely, does not need to pass through step by step regularly displacements in the middle of some of receiver.If this ratio is greater than a predetermined value, this receiver just is considered to so set up a dead band, can reduce synchronous overshoot fully synchronously.

Another kind according to the present invention specifically installs, and can measure the ratio of the amplitude of homophase and 90 ° of phase place coherent signals to a correlation detector in these correlation detectors, is used for signal in the detection noise.If much larger than one, can thinking, this ratio have a signal to exist; Otherwise this receiver is considered to receiving noise.When this receiver just thinks that the ratio that records is greater than predetermined value just Be Controlled go to attempt to carry out synchronously with the signal of coming in.

According to a further aspect in the invention, provide and can improve in the direct sequence spread spectrum code division multiplex system synchronous a kind of method between a transmitter and the receiver, particularly wherein some transmitters and at least one receiver all synchronously on the common timing signal source.Every transmitter is sent out one by pseudo noise code institute expanded data signal, this pseudo noise code be one have an appointment but common code sequences of different displacements all.Receiver is with to send out one synchronous by a transmitter of the pseudo noise code institute expanded data signal with predetermined codes sequence, and follow these steps to be synchronized on the timing signal source, to the speed sampling of data-signal by or its integral multiple identical with the timing signal source frequency, one or more data samples that come are in succession closed And produce a data sample point together, it is equivalent to a specific timing point in timing signal source, measure which data point again and have maximum, when maximum, just receiver is locked on the timing point in this timing signal source suitable with the measured data sample point.

It is the sort of to causing the redundant data channel of synchronously fuzzy every point sampling that an advantage of above method is that it does not need.In addition, last method allows data sampling rate to be higher than the frequency in timing signal source.The method that data sample that And comes in succession goes to produce a data point is closed in utilization, and data sampling rate can be greater than clean data transfer rate, the latter on effect be exactly the sample points of per second or code bit number (by close And one or more in succession data sample and get).This arrangement can make data sample close And (for example in a microprocessor) in number and allow the timing of data transfer rate and real hardware irrelevant.

From following detailed description, be familiar with the people of this technology for those, also horse back is known that the present invention also has some purposes and advantage, some concrete devices that the just the present invention who below shows and describe recommends just are used for illustrating optimal modes more of the present invention of thinking long and hard.Just as will be appreciated, the present invention can also make other and different concrete devices, and some details can also do some modification aspect tangible many, but all these does not leave this invention.Therefore, these figure and explanation all are regarded as illustration in nature, can not be as a kind of restriction.

The cutline of accompanying drawing

Fig. 1 is a DSSS(direct sequence spread spectrum) simplified block diagram of code division multiplexing receiver;

Fig. 2 is a representative of a bipolarity pseudo-random pulse sequence;

Fig. 3 is an auto-correlation pattern of the sort of bipolarity pseudo-random pulse of Fig. 2 sequence;

Fig. 4 represents to be equivalent in the code division multiplex system several auto-correlation patterns overlapping of adjacent transmitters;

Fig. 5 is the signal of adjacent transmitters is separated back Fig. 4 by shield segment a figure;

Fig. 6 (a)-6(d) is the waveform that explanation produces ternary sign indicating number;

Fig. 7 is the simplified block diagram according to a receiver of principle of the invention work;

Fig. 8 is according to desirable cross-correlation pattern between a local ternary sign indicating number sequence that produces according to the present invention and the two condition sign indicating number sequence of coming in;

Fig. 9 (a)-9(c) is the associative mode that is produced by the multichannel correlation detector in each concrete device according to the present invention;

Figure 10 be a receiver of the present invention various make quality low influence the time the real associative mode of working;

Figure 11 is with the concrete device of a kind of simulation of the multichannel correlation detector that decides degree of correlation according to the present invention;

Figure 12 is the simplified electrical circuit diagram of the concrete device of simulation of Figure 11 when using the two condition reference signal;

Figure 13 is the further simplified electrical circuit diagram of Figure 11 analog circuit when reducing the analog multiplexer number with Digital Logic;

Figure 14 (a) and 14(b) show two kinds of constructive methods of Figure 13 circuit;

Figure 15 is the Digital Implementation of a channel in Figure 11 circuit;

Figure 16 is the popularization of the N path channels of Figure 15 circuit realization;

Figure 17 is the another kind of Digital Implementation of Figure 11 single channel correlator;

Figure 18 is the popularization of the N path channels of Figure 17 circuit;

Figure 19 shows the associative mode of a homophase and 90 ° of phase places, has marked the position of the slave receiver channel of coherent detection among the figure;

Figure 20 (a) and 20(b) be the flow chart that receiver carries out two kinds of methods of fine tuning;

Figure 21 be receiver carry out whether fine tuning and detection signal exist based on microprocessor circuit;

Figure 22 is the flow chart whether timing of correction receiver and detection signal exist two kinds of methods;

Figure 23 is the flow chart that receiver carries out a kind of method of coarse adjustment;

Figure 24 (a)-24(e) is the time diagram that concerns between the commutator pulse between a transmitter and the receiver;

Figure 25 represents a transmitter and a receiver are locked in a circuit on the identical commutator pulse; And

Figure 26 represents to carry out in the receiver that data recover based on microprocessor circuit.

Realize optimal mode of the present invention

General introduction

In spread spectrum communication, expand signal bandwidth above being transmitted the normal required bandwidth of data, this expansion is to finish by laxative remedy, earlier the data that will launch are modulated a carrier waveform in phase shift keying (PSK) mode, then the signal that forms is modulated with reference to pseudo noise code by one, the code length of pseudo noise code is L, and its repetition rate is the twice of data transfer rate usually at least.Though the PSK modulation system is because the reason said in the past is often selected, other modulation system except that PSK also can be used for modulated carrier and expand this compound signal.

For this signal transmission of demodulation, received signal is to come heterodyne or multiply each other with a reference code identical with the sign indicating number of expansion during this compound transmission, and suppose that the sign indicating number of this emission and the local receiver code that produces are synchronous, so just removed by transmitter coding PSK and modulated caused carrier wave conversion, and in receiver, recovered the carrier wave that original baseband modulation is crossed.

Fig. 1 illustrates a kind of basic link that embodies the basic band spread receiver of one aspect of the invention.Receiver 100 has received a direct sequence spread spectrum (DSSS) signal, this signal is to be sent by a transmitter in some this transmitters, handle this received signal, the signal that this particular transmitter is sent out is differentiated from the signal that all transmitters are sent out.Should note, the signal of receiving is twice of modulated mistake, that is be, carrier wave is modulated by data, this composite signal is again by a pseudo-random code sequence modulation then, composite signal expansion can with a comparable bandwidth of the bandwidth of pseudo random sequence on, 100 pairs of signals of receiving of receiver provide the two-stage demodulation to extract the data of transmission.The DSSS signal that receives at first by heterodyne or multiply by this particular transmitter the sign indicating number, the signal of this particular transmitter will be differentiated in other signal.Therefore, suppose that the sign indicating number of transmitter and the sign indicating number that receiver produces are synchronous, caused carrier wave conversion is modulated by coding PSK by the transmitter place, has been removed at multiplier 102 places now, and has recovered the carrier wave that original baseband modulation is crossed.The carrier wave that is resumed of this narrow-band deliver to one design only allow this baseband modulation cross the band pass filter that passes through of carrier wave (drawing among the figure).With the local carrier wave that produces of exalted carrier and heterodyne or way of multiplying each other in multiplier 104 baseband signal is extracted then.The output of multiplier 104 is sent to a common correlation filter, and for example this is an integration and removes circuit, follows a sampling and holding circuit, so just draw the signal that is equivalent to launch data.

Receiver 100 is controlled by the microprocessor 108 of a standard, and microprocessor 108 is synchronous with system clock 110, and each transmitter is also synchronous with it.Because noise and unwanted also being transmitted in the multiplier 102 through producing the reference code same multiplication process that multiplies each other with this locality, this process is compressed on the original carrier bandwidths direct sequence signal that receives, but anyly is expanded on the bandwidth of a bandwidth that equals entering signal and reference code bandwidth sum with this local nonsynchronous entering signal of reference code that produces.Because this asynchronous input signal is mapped on the same with the reference code at least bandwidth, a band pass filter just can be got rid of a big chunk power in the undesired signal.The meaning of DSSS system that Here it is.

Synchronous input signal is transformed into the bandwidth of baseband modulation on the reference code modulation bandwidth, and the expansion still of asynchronous input signal is on code modulated bandwidth.

Synchronizing process is to utilize an inwardness of this special code of transmitter place employing.The auto-correlation of a maximum length (ML) sequence, also be exactly to move duplicating of back itself this sequence time of multiply by, synchronously the time is a spike, and loses (time difference between this yard and its replica code is near a code element or bigger) when synchronous, and auto-correlation just drops to-P ²/ L, wherein P is the amplitude of yard sequence, L is the length of sign indicating number.The symbol of auto-correlation figure is decided by the data symbols of modulation transmitter.Therefore, after Receiver And Transmitter is all suitably synchronous, monitor that this autocorrelative symbol just can recover the data that this is launched at the receiver place.

Referring to Fig. 2, receiver 100 tuning pseudo-random code sequence be ambipolar, that is the supposition constant voltage supply is gone its polarity of conversion.Adopt bipolarity rather than unipolarity in the present invention, in order that improve the efficient of power delivery, because carrier wave has been suppressed in the bipolarity transmission.The high concentration of energy in any frequency range has also been avoided in the bipolarity transmission, so also helps to avoid the interference between many different transmitters transmission in this system.Each bipolar sequence has an amplitude P and element duration T _CThe length of ML sequence is to decide according to the number that its signal in this system need carry out the multiplex different transmitters of code division.Every transmitter is designated same transmission code, but has the specific displacement that has nothing in common with each other of this public ML sequence.The length that therefore, in this system, can just be equivalent to this ML sequence by multiplex transmitter maximum number.

In this code division multiplex system, carry out noiseless multiplex transmitter number, equal the code length of this sequence in theory.For example for a ML sign indicating number that 63 bit lengths are arranged, this transmission channel can make 63 different transmitters carry out multiplexing in theory.This supposition when the sign indicating number that receives transmitter and the local sign indicating number that produces all synchronously on a public timing source, and its auto-correlation is when a spike, just is considered to finish synchronous between receiver and the transmitter reserved in advance.Yet in fact, in this system, can be encoded and cut apart that to carry out multiplex transmitter number much smaller more than this theoretical maximum, because in the auto-correlation of ML sequence, because-P ²The existence of/L item, adjacent correlation curve overlaps.Can know the understanding this point referring to Fig. 3, Fig. 3 shows an autocorrelator trace of single transmission, when Fig. 4 represents to have adjacent transmission, and several autocorrelator traces when promptly these transmission are offset a code element in time each other.

In Fig. 3, when the sign indicating number sequence with this locality generation of launching is offset in time each other greater than a code element T _CThe time, autocorrelative amplitude becomes-P ²/ L, wherein P is the absolute amplitude of this sequence, L is to be the sequence length of unit with the position.When the sign indicating number that produces with this locality of emission almost synchronously the time, i.e. when being offset less than a code element on the time each other, auto-correlation just increases on amplitude, and reaches peak value P fully synchronously the time ²Therefore, as long as monitor this autocorrelative output, synchronous can being detected between receiver and the transmitter, and when autocorrelation signal surpasses a predetermined positive, just be considered to set up synchronous.

Yet see Fig. 4 now, suppose the sign indicating number sequence K, K-1 and the K+1 that have three to be offset the emission of a code element each other in time.The same with Fig. 3, each is correlated with and has positive peak value P ²With negative peak value-P ²/ L.The correlation curve of adjacent code sequence is beaten dashed area at Fig. 4 and is overlapped each other.In these parts, the adjacent code sequence has common being correlated with, and makes it can not go to distinguish these transmission, in fact, for fear of the interference between transmission, need insert shield segment between sequence.This can specify transmission to such an extent that make the displacement of sequence be equivalent to the delay every a code element rather than the delay of the sort of each code element of Fig. 4.The result is, under best-case, compares with maximum in theory number, also has only the multiplexing of half number.In fact, in the code division multiplex system, when adopting bipolar sequence even half transmitter that also lacks than this theoretical maximum number might carry out multiplexing, because for fear of synchronous bluring, need than that bigger shield segment that is provided every a sign indicating number displacement delay is provided.

According to an aspect of the present invention, can carry out multiplex transmitter number only rises to and lacks one than theoretical limit, method is to adopt the cross-correlation of input signal and a ternary sign indicating number, this ternary yard be by be assigned to particular transmitter and receiver does not have the difference of the sign indicating number sequence of appointment to draw to it tuning sign indicating number sequence and one.In other words, at the receiver place, produce two bipolar codes, sign indicating number is exactly that of all transmitters common code sequence of launching duplicates, and its sequence bit is moved the sequence displacement that is equivalent to intended transmitter.Second sign indicating number is a replica code of public bipolar sequence, and has a sign indicating number sequence displacement that any transmitter is not all had appointment.A local sign indicating number that produces is deducted another local sign indicating number that produces, and the result is a ternary sign indicating number sequence, allows it and the signal decorrelation of coming in again.The static simultaneous techniques that below will talk about is adopted in the sequence displacement of ternary sign indicating number sequence, is to carry out in a code element of the sequence that the transmitter by preliminary election produces.Adopt the dynamic synchronization also will talk about below, can obtain between receiver and the preliminary election transmitter fully synchronously, the normally timing of mobile receiver and monitor that the output of correlator obtains continuously in a symbol ranges of this dynamic synchronization.When relevant output reached peak value, receiver and preliminary election transmitter were considered to synchronized with each other.Now the supposition Receiver And Transmitter also all with suitable clock (also be exactly, if transmitter is asynchronous on a clock, and receiver just is synchronized to another clock and gets on) synchronously, the polarity of relevant output is monitored the data that this transmission just can be extracted in the back.

Just how can better understand the tri-state impulse sequence of carrying out cross-correlation with transmitting sequence referring to Fig. 6 (a)-6(d) produces.In Fig. 6 (a), represented a bipolar sequence s(t who is launched), it has absolute amplitude P and code-element period T _CThis sequence is the simplification of actual sequence, and in the practicality, actual sequence will be longer, for example is 63.In receiver, produce the first reference pulse sequence r(t), shown in Fig. 6 (b).This sequence r(t) be with Fig. 6 (a) in the sequence s(t that sends by fixed in advance transmitter) identical because transmitter sequence has identical delay and is considered to synchronized with each other with the receiver sequence.

Receiver also produces the second reference pulse sequence e(t), that it sends with the preliminary election transmitter and all be the same sequence shown in Fig. 6 (c) with sequence that all other transmitters send, but the delay of sequence is not the delay of arbitrary transmitter appointment.

Draw poor (r(t)-e(t) of these two the local reference pulse sequence that produce), the tri-state impulse sequence of Here it is Fig. 6 (d).According to two reference pulse sequence r(t) with e(t) relative two condition value, this ternary sequence has arbitrary value in (+2,0 ,-2).

Here it will be appreciated that the sequence length of drawing in Fig. 6 example is 7.In fact, should adopt long sequence, go to carry out the code division multiplexing with the transmitter that adapts to quite a lot of number.

Referring to Fig. 7, with the bipolar pulse sequence of coming in carry out cross-correlation to be used for the ternary reference sequences that multiple signals separate be to produce in receiver 200.Receiver 200 receives launch pulse sequence s(t) after, just this sequence of coming in is delivered to the input of the first relevant relevant multiplier 204 of multiplier 202 with second.The first relevant multiplier 202 is the sequence s(t that come in) with the local reference pulse sequence r(t that produces) multiply each other, and r(t) the sequence displacement and the sequence displacement of intended transmitter be suitable.204 of multipliers are the sequence s(t that comes in) with pulse train e(t) multiply each other, e(t) have a pulse train displacement of never specifying.Result's product is all delivered to subtraction circuit 206, and this difference is carried out integration and removing in the correlation filter 208 of a standard, and the result draws output signal Y _Out

In Fig. 7, to point out list entries s(t) at first with two reference pulse sequence r(t) and e(t) multiply each other respectively, in subtraction circuit 206, carry out subtracting each other of product then.This and ask two reference pulse sequence r(t earlier) and e(t) poor, then difference and the sequence s(t that comes in) to multiply each other be equivalent.

Result's cross-correlation as shown in Figure 8.Note examining sequence r(t when the transmission of preliminary election and local the generation)-e(t) being moved away from each other a code element when above, every correlation curve all is 0 value.The cross-correlation curve of this and Fig. 3 can contrast, and Fig. 3 has the residual correlation value of a negative value, and size is P ²/ L.And when the sequence of preliminary election emission and the local reference pulse sequence that produces were synchronous, the amplitude of correlation curve just increased linearly, reaches peak value P(L+1 always)/L.

The advantage of this corresponding strategies can find out from the comparison of Fig. 9 a and Fig. 4 that Fig. 9 a represents the correlation curve of several adjacent transmission according to the present invention.Fig. 9 a some sign indicating numbers of 2 code elements of representing to be separated by particularly.Yet can recognize that several transmission of Fig. 9 a can be each other only have overlappingly every a code element and adjacent transmission several relevant, and in Fig. 4, dashed area occurs overlapping.Therefore, the present invention's length (unit for position) that can make multiplex number equal pulse train subtracts one.Can not there be this result in the system of technology before adopting.Even put into a shield segment between the transmission in the strategy of Fig. 9 a, reliable multiplex number is also much bigger than the reliable multiplex number of the corresponding strategies that adopts Fig. 4.

Suppose the code division multichannel psk signal Y(t that enters receiver) be expressed as following formula:

Y（t）＝ $\underset{\mathrm{j\; =\; 1}}{\overset{N}{\mathrm{\Σ}}}$ P _jd _jx _j（t）cos〔w _ct+o〕+N（t）（1）

Wherein, for N transmission that enters:

O＜t≤T, T are code-element periods;

P _jBe the power in each bipolar pulse sequence that enters;

d _jBe the polarity or the symbol of each suitable sequence that enters;

x _j(t) be the data that are transmitted;

w _cBe carrier angular frequencies, unit is a radian;

O is a carrier phase; And

N(t) be noise.

Adopt the output V of the common receiver of single reference code sequence _A(T) can define out by following formula:

V _A（T）＝P _rd _r+ (l)/(L)

P _jd _j+N _A（2）

P wherein _rBe the required power that enters sequence;

d _rIt is the data symbol of required sequence;

L is a pulse sequence length, and unit is the position;

P _jBe each power that does not need sequence;

d _jIt is the suitable data symbol that does not need sequence; And

N _AIt is noise.

Output V according to the receiver of principle of the invention work _B(T) can define out by following formula:

V _B（T）＝P _rd _r（l+l/L）+N _B（3）

Because correlation technique of the present invention comprises a subtraction with sign indicating number sequence of the sign indicating number sequence displacement that never provides, so at output V _B(T) in, all unwanted transmission components (" r " discerns with subscript) have removed fully, and in the receiver of former technology, output V _A(T) the transmission component of existing needs (subscript " r ") also has unwanted transmission component (having subscript " j ").

The ternary signal of multiplexer relevant with only with the common correlation ratio of the two condition pulse train of specific transmission, the white noise in that data-signal occurs with respect to receiver inlet on to the demodulation of noise will cause and add 3 decibels reduction.Therefore

N _A= N _B=0

（4）

N ² _B=2(1+1/L) N ² _A

Multiplexing strategy discussed above, the result makes us adopt random length ML sign indicating number in the code division multiplex system, and the transmission that does not need to enter is had the ability of refusal fully.In the past, have only the ML sign indicating number of sufficient length just can be used for some multiplexing potentially, and allow multiplex number than code length much less.Even the power imbalance problem of multiplexing transmitter also will occur like that.

Say that additionally the desirable cross-correlation figure of Fig. 9 a utilizes the method for the theoretical limit that surpasses sign indicating number from itself, also can draw the method for some multichannels, Here it is makes each time migration adopt more complicated receiver structure less than a code element and supposition.For example have been found that between each yard sequence shown in Figure 4, to add a sign indicating number again, just allow to be increased to 2 * (L-2) roads that only do some little sacrifice at the total signal of receiver on to noiseproof feature this moment as multiplex transmitter number.As Fig. 9 b, can between each sign indicating number shown in Figure 4, insert an extra-code.These yards all detect in several taps place of receiver.The output of each receiver tap shown in Fig. 9 b can be listed as follows:

Table 1

1. the sign indicating number that adds

2. 1/2 sign indicating number that adds

3. zero

4. 1/2 yard 1

Sign indicating number 1+1/2 sign indicating number 1 '

6. 1/2 yard 1+ sign indicating number 1 '+1/2 yards 2

7. 1/2 yard 1 '+sign indicating number 2+1/2 sign indicating number 2 '

Then each channel is solved the sequence of these equations:

Channel 1=2 * tap 4

Channel 1 '=2 * (tap 5-channel 1)

Channel 2=2 * (tap 7-channel 1 '-tap 4)

Channel 2 '=2 * (tap 7-channel 2-tap 5)

〃 〃 〃

〃 〃 〃

〃 〃 〃

Channel L '=2 * tap (2L+3)

In fact, because noise and stationary problem, some difficulty is done in above arrangement.Another kind method is need equal half part of maximum at relevant envelope to make carrier wave null value occur.Under this arrangement, for the output of each tap, equation becomes:

Table 2

1. the sign indicating number that adds

2. zero

3. zero

4. zero

The sign indicating number 1

The sign indicating number 1 '

The sign indicating number 2

This arrangement can make data recover fully and not interference, but it still wants how much to be subjected to The noise.In order to overcome the above problems, Fig. 9 c has shown a kind of arrangement, and wherein two or more yards combined sequence together and have buffer zone to separate.Group is to have nothing to do with this arrangement with group or by the definite separation method of several figures that are combined into and figure.This method also allows several the transmitters that similar characteristics is arranged are divided in groups, to simplify stationary problem.

Carry out any additional modulation and can combine with above-described strategy by the signal that is loaded with data in order to improve the needed measure of communication between the transmitter and receiver.The condition of unique requirement is the not essential timing of destroy displacement afterpulse sequence of any additional modulation, thereby keeps the sensitivity of receiver multichannel.

Synchronously-general introduction

Before the extraction data, the transmitter of receiver and preliminary election must be synchronous in time each other.Suppose Receiver And Transmitter all synchronously on a public fixed source (if the commercial power line is a transmission medium, common timing also can obtain from 60 hertz of power supplys), be exactly time relationship different propagation delays that are adapted to transmit and the delay that is adapted to timing signal and is adapted to the transmitter and receiver inherence that makes receiver synchronously.Wherein have some delays to fix, available " static state " postpones to compensate, and makes the transmitter of desynchronize in a code element each other this receiver and preliminary election, and one of them code element is defined as the bit period of pseudo-noise code generator.

In general, static delay can compensate at the initial timing signal of receiver, because most static delay is fixed.Yet when transmission medium is a transmission line, transmitter and receiver is all synchronously in a common timing source and when wherein the communication between two unit all be twocouese, has the difficulty can generation.So static delay must be from the consideration of getting on of two reference points, the one, transmitter is at the timing source place, and another is that receiver is at the timing source place.

If the emission seat in the plane receives what its place in office, seat in the plane at the timing source place, timing signal and transmit and will almost propagate into receiver from transmitter so with same speed.It all is because the delay that causes of transmitter and receiver circuit inside that between the transmitter and receiver other regularly changes, and can arrange in advance transmitter and receiver is carried out in a code element each other synchronously.Therefore, all receivers away from timing source all have identical static delay.

If yet receiving the seat in the plane at the timing source place and transmitter what its place in office, each receiver may need the transmitter of every distant place is had the static delay of a uniqueness, because the distance that signal is propagated is different.Therefore, make a receiver can receive the signal of many transmitters, the static delay of receiver must be variable.In fact, the static delay between each transmitter and receiver is measured when transmitter is installed; Static delay to all signal posts in the future of a particular transmitter need all arranges in receiver in advance.No matter when receive the transmission that a transmitter is sent, in order to obtain the combined synchronization of this transmitter, the timing of receiver can be adjusted to adapt to and this particular transmitter delay associated automatically.

In a kind of concrete device of the present invention, disposed some cover emittor/receivers unit, be arranged in what is called " master/pair " form.In this arrangement, there is a cover to be called the emittor/receiver unit of main website as source to other each station (secondary station) broadcast timing signal.Retardation together with timing signal between the secondary station of main website and each comprises the following: signal propagation delays, the coupling delay of main website and the emission filter delay of main website between the delay, main website that for example is used for filter delay, the main website receiving filter in timing signal source in the main website and the specific secondary station.The knowledge that these various delays have been arranged just can be made an estimation to the static delay amount that is correlated between the specific secondary station of main website and.But because the variation in the transmission line, together with influences such as variation of temperature, transmission frequencies, each postpones also with some variation.

Yet dynamic deferred adjustment can be with respect to these variations of major part in the static delay characteristic between the major and minor unit, but this moment, the multiplexing ability of this system may decrease, because in a certain specific master or pair unit, receiver must can be followed the tracks of the variation that postpones on one section scope that several code elements are arranged.This just requires one section enough wide buffer zone, makes the signal of two adjacent reception machines can do some temporal variation on their connected scopes and not cause interference.

But have now found that, required protection bandwidth can reduce with laxative remedy, go to measure between main website and each the secondary station in main website exactly with enclosing phase property and transmit relevant static delay with signal, periodically adjust the timing relationship of this transmitter signal then at the pair station, so that static delay is got back in the required scope.This just allows more pair and stands in emission in the same time, because can reduce greatly for postponing to change required buffer zone, makes how useful code delay be used for multiplexing.

By static delay set up synchronously, its variation can be compensated by dynamic deferred mechanism in each receiver.Dynamic deferredly comprise two steps: fine tuning and coarse adjustment.In view of static delay regularly make receiver and intended transmitter will be in a code element mutually synchronization mutually.Fine tuning then is to utilize coherent detection to carry out meticulous adjustment in the receiver timing, and it is as a function that receives transmission, and a function (static delay) that does not transmit as expection.

After fine tuning was set up, receiver was necessary to determine receiver institute " correct " this Di Mine whether the best is correlated with of this this Di Mine regularly this moment regularly at Xiang Guan Mine place, this ground.This needs, because according to the relevant nature of institute's code selection, and some other factor, it seems that several close Mine mutually, and this main ground Mine there is the biggest Mine value amplitude.This Ji Mine is to cause from the relevant institute of carrier wave in ± 1Tc Ma Xiang Guan Mine scope.At last must decision, appear at which pulse is suitable for doing synchronous use in the system's commutator pulse on each data bit.If there is not this decision, a kind of situation will appear, and promptly transmitter is locked on the commutator pulse and receiver is locked on another commutator pulse.This is because data two commutator pulses were arranged in the cycle, and incorrect timing can cause a kind of quadrature condition between transmitter data cycle and the receiver cycle data.Thereby for the cycle data of this quadrature, net energy is zero.Even Receiver And Transmitter is synchronized with each other, data still can not be extracted from the sequence that receives, because can not detect and transfer of data is decoded out this moment, unless Receiver And Transmitter all is locked on the identical commutator pulse.About fine tuning and coarse adjustment and in each data value inter-sync to suitable commutator pulse, also will be described in detail now.

Figure 10 explanation is carried out the relational graph that cross-correlation draws by accompany its carrier wave of a bipolar pulse sequence that enters with the local ternary reference sequences that produces.This associative mode is at receiver timing V ₁There is Yi Zhu Mine at the place, at receiver timing V ₂, V ₃, V ₆And V ₇As " channel ", there is little Xiang Guan Mine at the place hereinafter.At main channel V ₁The Mine that closes mutually at place depends on by the relevant nature of code selection, and postpones a poor function as symbol time between sign indicating number sequence of coming in and the reference code sequence.When Receiver And Transmitter reaches synchronous, this relevant Shi Zai Mine value, when synchronization discrepancy near a code element or when bigger, relevant absolute value drops to zero.It should be noted that the relevant difference of Figure 10 seldom is sine-shaped owing to the incomplete relevant nature of this yard and owing to the influence of sinusoidal carrier to being correlated with, more once Fig. 9 a does not wherein comprise carrier wave, and it is the desirable correlation curve of piecewise linearity.Here it is needs the reason of coarse adjustment; Fine tuning is the timing of adjusting receiver, up to having determined a Xiang Guan Mine; Coarse adjustment goes to determine whether this Xiang Guan Mine follows channel V then ₁Principal phase Guan Mine, still follow channel V ₂, V ₃, V ₆Or V ₇Little Xiang Guan Mine or Qi Ta De Mine.

According to an aspect of the present invention, receiver be synchronously by be tuned to several slave receivers that separate or the correlation detector of each receiver channel finish.Suppose each channel V ₁, V ₂, V ₃, V ₆And V ₇/ 3rd code elements that separate each other in time, the timing of this receiver is just adjusted in fine tuning so, and these channels all are on this ground Mine.In addition, suppose channel V ₁Be in just by a synchronous symbol ranges, this channel V so ₁Be in the sixth code element of this Di Mine.The output of these correlation detectors is all delivered to below with in the microprocessor of saying 314, so that produce a receiver timing signal and the extraction transmission data to the synchronous usefulness of transmitter.Drawn some concrete devices of this multichannel correlation detector of Figure 11-18.

Coherent detection

A kind of concrete device of multichannel correlation detector shown in Figure 11 is promoted into N correlated channels.Label 300 expression multichannel interlock circuits wherein all include a correlator 302 for each channel, and each correlator comprises one first multiplier 304, second multiplier 306 and subtraction circuit 308.The sequence S(t that first multiplier 304 has an input to receive into), also have second input to receive the first local reference sequences r(t that produces), the latter has the sequence displacement that is equivalent to the displacement of intended transmitter sequence.The sequence S(t that multiplier 306 has an input to receive into), also have one second input to receive the second reference sequences e(t), the latter has one never to give the sequence displacement of appearing.The sequence that each representative of these two multipliers 304 and 306 output is come in and the product of the reference sequences of these two local generations, and all be sent to the integration that work period and code-element period of bit rate be complementary and remove mode filter 310, just produce down column signal V for each channel like this _N:

V _N＝ ${\∫}_0^t$ S（t）〔r（t _N）-e（t _N）〕dt （5）

V wherein _NAnd S(t) all is analog signal, r(t _N) and e(t _N) all be the two condition signal.The output of integration and removing circuit 310 is sent to a sampling and holding circuit 312, and its monitors also stores this integrator output V _NSize and polarity.This value is if be sent to a common microprocessor 314, and microprocessor can respond from the output of all N detector 302, just can from predetermined transmission, extract the two condition signal, and can produce a signal of timing error and go to keep receiver synchronous with predetermined transmitter, these also will go through below.

Simulation multichannel correlation detector shown in Figure 11 need be to multiplier 304,306, and subtraction circuit 308, integration and removing circuit 310 and sampling and holding circuit 312 are carried out a large amount of demarcation adjustment.In fact, the detector of this 8 channels needs 80 to demarcate and adjust approximately.

If only utilize reference sequences r(t) and polarity e(t), the result can simplify this system greatly, only performance is brought a little reduction.Because these two reference sequences all are two condition (bipolarity) signals, do multiplication in a N channel correlators, can adopt analog multiplexer and inverter of a 2N shown in Figure 12 double input end.In this device, select input signal S(t by two condition reference signal decision) still select the input signal S(t of paraphase) deliver to subtraction circuit 308.The output of each subtraction circuit is exactly S(t in N subtraction circuit _N) (r(t _N)-e(t _N)), in the correlation detector 400 of Figure 12, each channel comprises one first dual input transducer 402 and one second dual input transducer 404, they are respectively by the first and second bipolarity reference sequences r(t _N) and e(t _N) control.In these two transducers 402 and 404, first circuit 406 is received in an input of each transducer, the sequence S(t that this line receives into), also have one second input to be received circuit 408, the sequence S(t that comes in that circuit 408 receiving polarities are put upside down by inverter 410).Transducer 402 and 404 all passes through driver 412 and 414 by reference sequences r(t _N) and e(t _N) drive.

Suppose r(t _N) and e(t _N) polarity identical, these two transducers 402 and 404 all are connected to circuit 406.So list entries S(t) just be sent to the positive input terminal and the negative input end of subtraction circuit 308, a zero-signal is delivered to integration and is removed circuit 310(Figure 11 as a result).If r(t _N) just be, e(t _N) be negative, transducer 402 is received circuit 406, and transducer 404 is received circuit 408.Therefore, sequence S(t) deliver to the positive input terminal of subtraction circuit 308, paraphase sequence S (t) is sent to the negative input end of circuit 308; The result is sequence 2S(t) deliver to integration and removed circuit 310.On the other hand, if the relative polarity of these two reference sequences is all put upside down sequence S(t so) deliver to the negative input end of subtraction circuit 308, the list entries S (t) of paraphase delivers to the positive input terminal of subtraction circuit 308; Consequential signal-2S(t) be sent to integration and removing circuit 310, so satisfy equation

V _N（t）＝S（t _N）〔r（t _N）-e（t _N）〕

The circuit of Figure 12 is more superior than the circuit of Figure 11, because in Figure 12, though inverter 410 needs two to demarcate adjustment (balance and biasing), the demarcation adjustment of analog converter is unwanted.To one 8 channel detector, required adjustment number difference seldom can reduce to 34 from 80.

Referring to Figure 13, then the circuit of Figure 11 can also further be simplified, as long as recognize that being input to each integration and removing what go in the circuit 310 is the poor of two signals, one of this two signal is list entries S(t) multiply by+1 or-1, and output is zero when two reference sequences are equal to each other.According to Figure 13,2N multiplier and N subtracter all change the analog multiplexer 502 of N three inputs in circuit 500.An input of each transducer 502 is connected to and receives list entries S(t) circuit 504.Second input of transducer 502 is connected to circuit 506, and the latter receives by 508 anti-phase list entries S (t).The 3rd input of transducer 502 is connected to circuit 510, and the latter links to each other with ground wire again.

The first reference sequences r(t _n) control input end of directly linking transducer 502 through an inverter/driver 512.Be connected to the anticoincidence circuit 514 that also has of transducer 502 control input ends, the latter has two inputs respectively to meet reference sequences r(t _n) and e(t _n).

When two reference sequences were equal to each other, the output of anticoincidence circuit 514 drove transducer to circuit 510, made the output of transducer 502 produce a zero-signal to integration/removing circuit 310(Figure 11).If the first sequence r(t _n) equal 1, the output V(t of transducer 502) equal S(t).If but r(t _n) equal 0, transducer output V(t) just equal-S(t).Therefore the output of subtraction circuit just produces signal S(t _n) (r(t _n)-e(t _n)), and to each channel, the output of this integration and removing is exactly required

${\∫}_0^1$ S（t）〔r（t _n）-e（t _n）〕dt （6）

Figure 14 a and 14b respectively represent to make among Figure 13 two circuit of three input analog converters 502.In Figure 14 a, each all has following characteristic in the transducer 600,602 of two two inputs:

When A=0, X=X ₀;

When A=1, X=X ₁

The first reference sequences r(t) is connected to the control end A of transducer 600 and be connected to an input of anticoincidence circuit 604.The second reference sequences e(t) is connected to one second input of anticoincidence circuit 604.The output of exclusive-OR gate 604 is connected to the control end A of transducer 602.The sequence S(t that comes in) is connected to an input X of transducer 600 ₁, and, be connected to the second input X of same transducer by inverter 606 ₀The output X of transducer 600 is received an input X of transducer 602 ₁, the second input X of transducer 602 ₀Earth connection.

Among Figure 14 a, the output V(t of transducer) can be by the following required equation V(t that is equivalent to)=S(t) (r(t _n)-e(t _n)) truth table define out.

Table 3

r（t） e（t） r

e V（t）

0 0 0 0

0 1 1 -S（t）

1 0 1 S（t）

1 1 0 0

In the concrete device of three input transducers 606 shown in Figure 14 b, different according to the two condition value of two control input end A and B, output X be selectively with four input X ₀, X ₁, X ₂, X ₃In arbitrary input link.List entries S(t) direct and input X ₂Link, and by an inverter 608 and input X ₁Link.Input X ₀And X ₃Ground connection all.Two reference sequences e(t) and r(t) each links with two the control input end A and the B of transducer 606.

The action of transducer 606 can be described with above truth table of deriving as Figure 14 a, so required output V(t also can be provided).

The coherent detection implement body device of Figure 11-14 is all based on to this analogue technique of the integration of a continuous signal.If replace analog integration in the correlation detector with the summation of discrete signal, the number of then required demarcation adjustment also can further reduce.Referring to Figure 15, this is the correlation detector 700 that each channel for receiver provides, the sequence S(t that it makes into) digitlization, and on the time cycle that equals a bit period, this digitized signal is carried out the algebraically summation in accumulator.The initial value in the accumulator and the difference of final value are represented S(t) integrated value on a bit period.Add up by reference sequences r(t) and value e(t) control.When two reference sequences equated, accumulated value did not change.As r(t) and when e(t) unequal, according to r(t) value, adding up is to increase or subtract a S(t) value.

Correlation detector 700 comprises an analog digital converter 702, and the latter receives simulated series S(t) and in output D generation digital signal corresponding.The output of analog digital converter 702 is sent to an input A of adder/subtracter circuit 704, and the input of an accumulator register 706 is delivered in the output of this circuit.Output register 708 is delivered in the output of accumulator 706, is added to the second input B of adder/subtracter 704 simultaneously.The action of unit 702-708 also has the action of sequencer 710 all to be synchronized to a bit period T.Sequencer 710 is controlled the conversion time of A/D converter 702 and adding up the time of accumulator register 706 respectively at output 712 and 714.Accumulator register 706 by exclusive-OR gate 716 and AND gate 718 by two reference sequences r(t) and e(t) control.

Adder/subtracter 704 is as reference sequences r(t) when being 1, produce an output signal, it is digital list entries S(t) and accumulator register 706 in the content sum, and as reference sequences r(t) when being zero, it is accumulator register content and list entries S(t) digital value poor.Two signals that are added on adder/subtracter input A and the B are carried out addition and subtraction, are by being added in signal controlling on the input F, and this signal is by reference sequences r(t) generate by an inverter 720.

If r(t) equal e(t), exclusive-OR gate 716 produces a logic zero signal, and the latter is sent to an input of AND gate 718.Another input of AND gate 718 is the cumulative signal that writes by sequencer 710.Sequencer 710 alternately produces " conversion input " signal and delivers to A/D converter 702, make list entries S(t) conversion of an analog to digital is provided, with " write accumulator " signal of generation, make on existing accumulated value S(t) instantaneous value add or deduct, and deliver to output register 708, deliver to then and can produce two microprocessor 314(Figure 11 that advance value output signal and signal of timing error).

Therefore, as r(t) equal e(t) time, under the control of exclusive-OR gate 716, the content of accumulator register 706 remains unchanged.As r(t) when equaling logical one, the content of accumulator register 706 is the sequence S(t that increased) value, and as r(t) when equaling logical zero, the content of accumulator register is the sequence S(t that has reduced) value.This has just had at S(t) on multiply by+1 or-1 and the effect of integration.

The correlation detector of Figure 15 can be promoted into the correlation detector 800 of N the channel of Figure 16.Reference sequences r(t _n) and e(t _n) all delivering to an input latch 802, the latter has r(t _n) and e(t _n) output deliver to a pair of N respectively than on 1 the transducer 804,806.The input of exclusive-OR gate 808 is delivered in the output of these two transducers 804,806, and this exclusive-OR gate is by AND gate 812 control accumulative registers 810.

Accumulative register 810 among Figure 16 is equivalent to the accumulator register 706 among Figure 15.Yet memory 810 contains many memory blocks that are equivalent to each channel, and comes addressing by channel sequencer 814, and the latter is controlled by the output of sequencer 816.Equally, the output of accumulative register 810 is sent to output storage 818, and the latter is equivalent to the output register 708 among Figure 15.Memory 818 contains many memory blocks that are equivalent to correlated channels, and comes addressing by the output of sequencer 816.

The sequence S(t that comes in) be sampled with holding circuit 820 and sample, and be sent to simulate to digitalizer 822 the simulated series S(t that comes in therein) be digitized, deliver to adder/subtracter 824 by the described mode of Figure 15 then.

In operation, sampling and 820 couples of simulated series S(t that come in of holding circuit) sample, and these samples be transformed into by microprocessor 314(Figure 11) generation the time also adds to the synchronous suitable digital value of bit period T on the sequencer 816.Each memory block of accumulative register 810 is by sequencer 816 addressing, according to reference sequences r(t in suitable channel) value, the content of accumulative register 810 is to be increased or to reduce by a S(t) current value.Circuit 800 is just so continuously to list entries sampling, and under the control of channel sequencer 814 and sequencer 816 and microprocessor 314, each this sequence of channel N multiply by+and 1 or-1 and integration.So accumulative register 810 and output storage 818 like this along with the time synchronized of each signal the channel sequencing be sampled and holding circuit 820 and input latch 802 storage lives between can monitor N the channel that adds up.

Referring now to Figure 17,, this is that the another kind of digital device correlation detector 900 of individual channel correlation detector comprises a common voltage to frequency changer 902, and the latter crosses an absolute value circuit 904 and receives list entries S(t) absolute value.Absolute value electricity 904 needs, because voltage is to frequency changer 902, just because of it is only the unipolarity input signal to be played response usually.The preface S(t that voltage is come in to frequency changer 902 handles) instantaneous amplitude is transformed into the signal of independent suitable frequency, " delivers to forward-backward counter 906 with an input of door 908 by one again.

List entries S(t) also be added to simultaneously analog comparator 908, the latter can follow the tracks of defeated sequence S(t) polarity.In other words, the output of analog comparator 908 is representative input row S(t) symbol.Reference sequences r(t) and e(t) all pass through the remaining input of exclusive-OR gate 910 to door 908.

Forward-backward counter 906 is controlled by second exclusive-OR gate 912, and the latter receives the output and the first reference sequences r(t that intends comparator 908).So, as list entries S(t) symbol and reference sequences r(t) symbol when identical, the forward-backward counter Be Controlled must go to increase; Otherwise counter will go to reduce.The output of counter 906 be sent to the synchronous latch 914 of bit period T on.

As two reference sequences r(t) and e(t) when being equal to each other, the clock CLK of forward-backward counter 90 is forbidden by exclusive-OR gate 910.Otherwise, the counter clock enabling, and counter 906 is being followed the sequence S(t that comes in).In other words, as r(t) when being 1, counter is to sequence bit S(t) positive polarity counting upwards, the sequence bit S(t of anticathode) counting downwards.As reference sequences r(t) when being logical zero, adding up is deducted, and counting direction is opposite.

The circuit 900 of Figure 17 can be promoted into the coherent detection of N channel with the circuit among Figure 18 1000.In circuit 1000, voltage to frequency changer 1002, absolute value circuit 1004 and analog comparator 1006 all is equivalent to the suitable parts among Figure 17, and all public to all channels.Yet, forward-backward counter 1008, AND gate 1010 and exclusive- OR gate 1012 and 1014, each channel configuration one cover.The output of each up/down binary counter 1008 is sent to latch 1016, the common synchronization period T that puts in place.Microprocessor 314(such as Figure 11 are all delivered in the output of this N latch), the latter can handle the coherent signal of these individual channel, and produce the binary data that recovers from intended transmitter and produce some timing signals, make the timing of receiver move to such an extent that keep synchronously with intended transmitter.

Dynamic synchronization

As discussed above, static relating to synchronously set up some predetermined delays in receiver, and these delays are equivalent to different propagation time of being associated with different transmitters.Static delay in this receiver that just presets when beginning to be provided with can make transmitter and receiver synchronized with each other in a symbol ranges.React to set up completely by 314 pairs of coherent signals that produce by above-mentioned many correlation detectors of microprocessor then and be correlated with.

Microprocessor 314 carries out special processing to the coherent signal of these channels, with the timing of two kinds of step receiver control, make it to carry out synchronously with predetermined transmitter, this two step is exactly fine tuning and coarse adjustment, when needing, also and then synchronous correction is done in some suitable pulses of system clock.

Still referring to Figure 10, wandering back to coding relevant is that symbol time postpones a function of difference between the sign indicating number received and the reference code, and depends on the special relevancy matter of used sign indicating number, relevant You Yi Mine when reaching synchronous, and when synchronism deviation near a code element or when bigger, relevant absolute value falls to zero.Data are recovered from associative mode, and the symbol that method is based on associative mode depends on the numeric data code position that is used for modulating this transmitter.Therefore, after Receiver And Transmitter is suitably synchronous each other, can close the monitor voltage V of channel place in principal phase ₁Symbol way the emission data recover out.

Fine tuning

Referring to Figure 19, this is an associative mode that is equivalent to Figure 10 associative mode, now represents with 1100.This is " homophase " associative mode, is decorated with thick correction channel V among the figure ₁, V ₂, V ₃, V ₆And V ₇, they are all used and which decide close Mine mutually be equivalent to main channel, and main channel has maximum relevant synchronously the time.A pair of additional channel V ₄, V ₅Be thin correction channel, or be the fine setting correction channel, they make main channel V ₁Relevant output become greatly keep receiver synchronously.It should be understood that in the former discussion that all references to part code element all are related to the ratio that carrier frequency and sign indicating number produce frequency.As an example, if carrier frequency is 5670 hertz, it is 3870 yards bps that sign indicating number produces frequency, so just relevant with ratio 3/2 to the reference of part code element, it allows every code element that 3 Ge Mine are arranged.Also having a correlation curve 1200 among Figure 19 is 90 ° of phase place correlation curves, it to the displacement of homophase correlation curve 90 °.The meaning of 90 ° of phase place correlation curves is, when homophase correlation curve when being very big, the value of 90 ° of phase place correlation curves is zero.Will discuss as following, and adopt 90 ° of phase places relevant, and can simplify signal processing, particularly simplify the detection of Xiang Guan Mine.

Because three Xiang Guan Mine are arranged, suppose principal phase pass channel V in each code element ₁Be in and be about in the suitably synchronous code element main channel V ₁Be " in the sixth symbol ranges of local ” Mine.Fine tuning makes this receiver go down to adjust its timing in the control of microprocessor 314, makes the correlated channels V of 1/3rd code elements that separate each other ₁, V ₂, V ₃, V ₆And V ₇All the position is at its this Di Mine value place.Adjust the timing of receiver to such an extent that make these five correlated channels all the position is at this Di Mine, it is the order searching method that shows in the flow chart that provides with Figure 20 (a) that a kind of method is arranged.This comprise adopt one and longly be 2(PS) preamble, wherein S is a number of times level and smooth on every, and P equals 1/6(in this example) code-element period is divided by the dependent resolution of receiver, or receiver from synchronous zero point Tiao Zheng Dao the associated numbers of times of the needed minimum resolution of Mine value.

For each data bit of preamble, the receiver principal phase is closed channel V ₁Timing be adjusted the minimum score 1/6(P of a code element) (step 1320), simultaneously associated voltage V ₁Amplitude store (1330).Repeat this process and all changed its timing (1340) on one section 1/3rd code element in whole maximum, select relevant V then up to receiver ₁Amplitude be a maximum point as this Di Mine (1350), and the timing of adjusting receiver makes channel V ₁The position is on this position (1360).

Another kind of fine tuning method by microprocessor 314 controls is the fine tuning channel V that adopts among Figure 19 ₄And V ₅The fine tuning channel V that provides by a pair of additional correlation detector (drawing among the figure) ₄And V ₅, all close channel V with principal phase in time ₁Be offset a code element mark that equates less than 1/6 code element.Also can select a preamble in this law for use, it has length PS under worst case, and it is 1/6(P that minimum receiver is proofreaied and correct (resolution)) code element.Referring to Figure 20 (b), associated voltage V ₄And V ₅Associated voltage V with main channel ₁All be added in the microprocessor 314 (step 1950) together.Compare V ₄And V ₅Relative amplitude (step 1960,1970), microprocessor just determines the direction (step 1980,1990) that receiver regularly will move, and makes main channel V like this ₁Be on the main Ben ground Xiang Guan Mine.Figure 21 has shown this system with sketch.For simple meter has omitted the program of microprocessor 314 here, but, compile this program and can think routine work based on the flow chart of Figure 20 (b) simplification and the discussion here.

Also having a kind of fine tuning method is to adopt a channel, and the timing of this channel produces by 90 ° of phase carriers.Know from Figure 19, appear at the Yi Xie Mine value place of homophase associative mode 1100 zero point of 90 ° of phase place associative modes 1200,, can produce an error voltage by microprocessor 314 according to the symbol of homophase and 90 ° of phase place two figure products.The symbol of error voltage is just pointed out the direction that receiver regularly must move, and the receiver correlated channels is synchronized on this ground Xiang Guan Mine.Utilize the amplitude of homophase and 90 ° of phase place associated voltage 1100 and 1200, not only can determine receiver to move direction regularly synchronously, and can determine in order to reach the required amount of movement of this Di Mine in order to reach.

Therefore, according to a further aspect in the invention and the method for being summed up in the flow chart as Figure 22 (a), measure homophase associated voltage V ₁With 90 ° of phase place associated voltage V _1q(step 2050) calculates homophase associated voltage V ₁With 90 ° of phase place associated voltage V _1qRatio (2060), if this ratio is just (2080), two relevant just is considered to have identical polarity, so must increase receiver delay (2095) regularly; Otherwise, be correlated with for these two and be considered to have opposite polarity, should reduce receiver constant time lag (2090).If receiver and intended transmitter are synchronous fully, in order to prevent receiver change regularly, and for fear of in receiver by the confusion that postpones to cause, can utilize the information more more Zao to make the judgement of correction, and supervision ratio V than a data bit ₁/ V _1qAbsolute value, the latter mainly is a cotangent function.This can with the memory of microprocessor 314 couplings in deposit a form, this form is ratio V ₁/ V _1qConnect with the fine tuning number of corrections that will reach optimal synchronisation, for example each correction will be moved 1/48th of a code element, and this form is listed as follows:

Table 4

The number of times V that proofreaies and correct ₁/ V _1q

(a code element mark that equates)

0 ∞

1 5.02

2 2.41

3 1.49

4 1.00

5 0.668

6 0.4149

7 0.1999

8 0

Therefore, can be for receiver number of corrections regularly directly from V ₁/ V _1qMake, when ratio greater than 5.02 the time, proofreading and correct has a dead band, its can near cancellation receiver searching back and forth optimal synchronisation.In addition, receiver is moved to the required data bits of Xiang Guan Mine from a suppressed zero also can be from 8(in this example) be reduced to 1, this just reduces to the length of any required preamble minimum and has quickened and seeks in proper order.Last this might be forbidden carrying out tracking correction on several data bit in succession, but do not reduce the following rate of receiver, thereby eliminated overshoot.

The detection that signal exists

90 ° of phase place associated voltage V have been arranged _1qAnd homophase associated voltage V ₁, may determine in noise background also further whether a signal exists.As the flow chart of Figure 22 (b) summary, when the input of receiver has only noise, in-phase voltage V ₁With 90 ° of phase voltage V _1qSimilar all is identical value K, so ratio V ₁/ V _1qApproach 1.But if signal and noise exist simultaneously, fine tuning makes V ₁For greatly making V _1qFor minimum, the ratio of gained substantially exceeds 1, thereby V ₁/ V _1qRatio can be used as a kind of indication that signal exists.In fact, can monitor this ratio on several data bit, employing smoothing technique or the method that the minority is subordinate to the majority are guaranteed precision.

Figure 21 has represented in noise background to detect the circuit whether signal exists, and this is that the output of 314 pairs of correlation detectors discussed above of microprocessor responds and produces signal V ₁And V _1qSignal V ₁, V _1qHandle with microprocessor 314, produce ratio V ₁/ V _1q, again V as a result ₁/ V _1qAbsolute value compare with a predetermined threshold value, be to have a transfer of data in the signal that decides into like this or only be noise.

After the decision, this receiver is adjusted to Mine place, this ground with regard to the method with above-mentioned fine tuning, needs then to decide whether " correct " this ground Mine of present this ground Mine by coarse adjustment, so that receiver has is best relevant.

Coarse adjustment

According to a kind of concrete device, receiver can guarantee that to the coarse adjustment previously selected transmitter this receiver is tuned on the maximum Xiang Guan Mine rather than transfers on the Zai Fu Shu De Mine, seek comprising order, after fixing a point as one Di Mine, receiver will be adjusted on the multiple of 1/3rd code elements, measures the amplitude of received signal at Mine place, each adjacent ground.After the amplitude decision of Zhe Xie Mine, go again to determine whether Zhe Mine be suitable.Because the influence of channel model distortion, near the difficult each other difference of the amplitude of the adjacent Ji Mine associative mode center, at this moment can adopt the method for common " mass centre " to differentiate maximum this Di Mine, this decision is based on the relative value of all each channels, does not just select the channel of a maximal correlation amplitude.

Microprocessor 314 is programme with coarse adjustment order searching modes, make receiver after identifying this Di Mine, move the integral multiple of 1/3rd code elements in the timing again, measure and store these relevant amplitudes, and identify a correct Mine of pass mutually with mass centre or other method.Order is sought needs the transmission preamble that length is WS, and wherein W is the width (is unit with 1/3rd code elements) of Mine value hunting zone, and S is a figure place level and smooth in the voltage readings.

Figure 23 is that microprocessor 314 provides order to seek the block diagram of simplifying procedures of coarse adjustment, and it comprises a check at step 1200 place, still use fine tuning discussed above, and whether the position is on this ground Mine for the decision receiver.If at this ground Mine, receiver is not wanted fine tuning to receiver, receive the seat in the plane at this ground Mine up to this.Being in after this ground Mine, adding an increment (step 1202) in the timing of this receiver, is at K+N up to its timing, the timing of this ground Mine that draws when wherein K is fine tuning, and N is the number of how many individual 1/3rd code elements of a decision of predesignating.Measure and store the correlation (step 1204) of K+N, the timing of receiver reduces by 1/3rd code elements (step 1206) then.Measure and store relevant (step 1208) of this receiver and intended transmitter now.Whether the timing of Verification Receiver determines it in that (whether K-N) ， Calipering is in the opposite side (step 1210) of initial this Di of detection Mine K.If not, reduce the timing of receiver again, and measure with to store this relevant.Up to being, all check once (step 1212) relevant to determine Yi Mine value all storages relevant.

According to another kind of concrete device, in order to reduce the length of preamble, can adopt a plurality of auxiliary receiver channels, these channels are at main channel V ₁Both sides are offset 1/3rd yards integral multiple each other, and they produce principal phase and close signal and some additional related signals, and all deliver to microprocessor 314.Microprocessor 314 is differentiated the main channel V with maximal correlation with the program of mass centre or other analytical method ₁With some auxiliary channels.Need not seek circuit or program in proper order owing to adopted a plurality of receiver channels or correlation detector, the required preamble length of coarse adjustment can be reduced to level and smooth figure place S.Certainly this supposition is closed channel V for required search width in principal phase ₁The public skew of both sides 1/3rd code element multiples on have a channel to exist.

A plurality of receivers have been arranged, just need not work out the order finder of microprocessor.What replace is that the program of microprocessor 314 only needs to lose simply the relatively full output of transferring at this Di Mine of these correlation detectors, and identifies an amplitude peak De Mine.

The correction of timing signal

If the bit rate of transmission data is less than half of the pulse recurrence rate of timing source, transmitter and receiver might be locked on the different commutator pulses, seems fully synchronous though seem them.For example, numeric data code speed is 30 yards positions of per second, and the commutator pulse source is 60 hertz, and the carrier frequency position is between 60 hertz of harmonic waves, and then transmitter may be locked on 60 hertz of commutator pulses, and receiver is locked on next 60 hertz of commutator pulses.Be not fully synchronously between Receiver And Transmitter, because the receiver data are regularly recovered irrelevantly, the transfer of data of an alternation just can not be detected.

For this conditioning theory is got clearer, Figure 24 (a) represented receiver and predetermined transmitter all to some synchronous commutator pulses.Figure 24 (b) is a carrier of transmitter, and Figure 24 (c) is 1 and zero emission data of representing alternation.Suppose that Receiver And Transmitter is all synchronous on identical commutator pulse, the integration of receiver and removing circuit 310 will be synchronized to the emission data, and in the place's removing of the back edge of each data, shown in Figure 24 (d), some of them " point " expression integration removing point.So the output of integrator after the sampling is exactly to be embedded in duplicating of data in the transmission.

But if transmitter and receiver is not synchronously on same commutator pulse, integration and remove circuit 310 can not with the data of launching have suitable synchronously.This situation is shown in Figure 24 (e), and the some of them integration is removed point and appeared between the transmission data, and the sampling output of integrator 310 all is 0.

In other words, Receiver And Transmitter is as if asynchronous on same commutator pulse, but difference is synchronous on two commutator pulses that link to each other, and just can not recover arbitrary transmission data.Therefore must check this Receiver And Transmitter, guarantee that they are all synchronously on same commutator pulse rather than synchronous two commutator pulses that linking to each other.

According to an aspect among the present invention, with main receiver channel V ₁Be associated, an auxiliary receiver channel V is arranged ₁', the latter has an additional delay that is contained in half inner numeric data code position.So two channel V ₁And V ₁' in a signal that can detect this emission is always arranged.With the data preamble of an alternate, deliver to the auxiliary receiver channel of advocating peace together with this transmission, just can make decision.The amplitude of the relevant output of this two receiver channel relatively, correct channel (having big correlation magnitude person) are exactly and the transmitter channel on same commutator pulse synchronously.Data just monitor on " correct " channel.

Figure 25 is used for the synchrodyne Receiver And Transmitter that can make regularly to be locked in simplified electrical circuit diagram on the same commutator pulse.Microprocessor 314 produces an auxiliary channel V ₁', the latter is to channel V ₁Be offset data bit half.To the sequence that enters of a preamble with alternate, microprocessor is channel V relatively just ₁With channel V with half yard position delay ₁' the data output amplitude, and identify a channel that has by a relatively large margin.This channel just is considered to be locked in channel on the same commutator pulse with transmitter, and is added to microprocessor again and recovers to use as data.

In the concrete device of another kind of the present invention, also can remove auxiliary receiver channel V ₁' needs.When the timing reference frequency is less than or equal to data sampling rate, and when the ratio of data sampling rate and timing reference frequency is an integer, continuous several data samples are combined draw a data point or numeric data code position, this moment, transmitter and receiver can be by synchronously.Merged these data sample points, received an alternately preamble of negate simultaneously, more all possible and several sizes is also selected the sample that provides maximum output, just can make the data sample point an of the best.If each sample is assigned on its synchronous points, lock onto this time that provides maximum output so just can finish synchronously.

For example, the frequency of timing signal is 60 hertz, and data sampling rate is per second 30 samples, and for the data transfer rate of 30 yards positions of per second, each data sample is used to draw a data point or numeric data code position.For the data transfer rate of per second 15,7.5 or 3.75 code values, will provide a numeric data code position with 2,4 or 8 data samples in succession.Except removing the needs to the redundant data channel, last method has also been removed will the requirement identical with data transfer rate to the data sample rate.In fact, sample rate can be higher than data transfer rate.This just allows a plurality of data samples are merged in number, for example merges in microprocessor, and allows data transfer rate not rely on the timing of actual hardware.

Data are recovered

In spread spectrum system, it is well known that data are recovered, and material as a setting can be with reference to book 5.3 joints of above-mentioned Dixon work, particularly since 155 pages the discussion about Costas ring demodulator.

Because the spread spectrum system that provides here comprises a plurality of correlated channels, so according to one aspect of the present invention, can in each channel, extract data rather than only in single correlated channels, extract, so improved the data recovery, thereby might reduce the message error rate of system, and for receiver synchronously, also might shorten or eliminate the length of any required preamble.

Still referring to Figure 19, the center of noting associative mode 1000 is to close channel V in principal phase ₁Near.Principal phase is closed channel V ₁Symbol depend on the data symbol of launching.Therefore, V ₁On the occasion of the logical one that is equivalent to launching, and relevant V ₁The negative value logical zero that is equivalent to launching.

At V ₂, V ₃, V ₆And V ₇The relevant of place also has and the suitable value of symbol of launching data.Specifically say, when not having noise and distortion, channel V ₁, V ₂, V ₃, V ₆And V ₇Voltage output between following relation arranged:

V ₂＝V ₃＝R ₁V ₁

（7）

V ₆＝V ₇＝R ₂V ₁

Wherein

R ₁＝- 2/3

R ₂＝ 1/3

According to the present invention, set up suitable receiver synchronously after, the data symbol of each correlation detector output all can be monitored.Data also can be used channel V ₁, V ₂And V ₃Output extract, depend on the characteristic of noise and distortion, the gain of its effective signal-to-noise ratio is

K wherein _jBe V _jTo V ₁The noiseless relative amplitude, j=2,3, (k when not having distortion _j=R ₁), L is a pseudo noise code length, u _jFor to V _jWeighted factor, j=1,2,3.Weighted factor will be selected according to the certain distortion that exists.

Figure 26 is one and simplifies circuit, 314 couples of channel V of expression microprocessor ₁, V ₂And V ₃Deal with, and output that program merges all these three correlated channels is arranged to extract the transmission data, wherein weighted factor is to choose according to the certain distortion of known existence in the transmission medium.Table 5 has illustrated the improvement of signal to noise ratio under some possible distortions and weighted factor situation.

Table 5

An attendant advantages of recovering at the enterprising line data of all channels of receiver is can identify the random error and the burst error that can influence each channel and also can neglect.This be with above discussion to utilize the relevant output with 90 ° of phase places of homophase to do the detection that signal exists similar, but to use all each channels, be not two only relevant quadratures outputs with individual channel.

In addition, all correlated channels or at least on several correlated channels another attendant advantages of restore data be when receiving message, might monitor synchronously.Though when receiving message, can not adjust synchronously, adopt additional receiver channel, the content of message can be recovered when adjusting synchronously, does not need to retransmit.

Here in the content of Jie Luing, only show and described the present invention and recommended some concrete devices of usefulness; However, it is to be understood that the present invention can also be used for many other combination and environment, and can also do some in the inventive concept scope of here expressing and change or revise.

Errata 850401

85102959

Errata

Errata

Claims (25)

1, a kind of direct sequence spread spectrum code division multiplex system, it comprises:

A timing source;

Some synchronous transmitters on this timing signal source all, each emission data all use a bipolarity pseudo noise code to expand should this pseudo noise code has appointment and displacement inequality public bipolar code sequences all; And following feature is arranged:

A receiver that is synchronized to said timing signal source, be used for receiving said data-signal and sign and do not go out one by giving the signal that first selected transmitter sends, this signal is expanded by a bipolarity pseudo noise code, and this pseudo noise code have give first appointment but transmit the displacement of sign indicating number sequence different with other transmitter.Receiver comprises the device that can produce the first bipolarity pseudo noise code.This yard is the duplicating and the sign indicating number sequence displacement of giving first appointment arranged of public bipolarity pseudo noise code of emission.Can produce the device of the second bipolarity pseudo noise code in addition, this yard also is the duplicating of public bipolarity pseudo noise code of emission, but has the sign indicating number sequence displacement of never specifying, the device that is used for handling the said first and second bipolarity pseudo noise codes is arranged again, draw a ternary sign indicating number sequence thus, and comprise and be used for transmitting and said ternary sequence is carried out the device of cross-correlation said.

2, the system of claim 1, wherein said bipolar code sequence are a maximum length (ML) sequences.

3, claim 1 or 2 system, wherein said bipolar code sequence is a phase shift keying (PSK) signal.

4, in a kind of direct sequence spread spectrum code division multiplex system, comprise synchronous some transmitters at a common timing signal, one of every transmitter emission is by the expanded data signal S(t of bipolarity pseudo noise code institute), this pseudo noise code is to have to specify and displacement inequality common code sequences all:

Receiver on synchronous said timing signal is used for receiving and saidly has transmitting that the pseudo noise code of the sign indicating number sequence displacement of giving first appointment expands by a bipolarity, and following feature is arranged:

The device that produces one first bipolarity pseudo noise code is arranged, this pseudo noise code is the duplicating and have a sign indicating number sequence displacement of giving first appointment of public bipolarity pseudo noise code of emission, the device that produces one second bipolarity pseudo noise code is arranged, this pseudo noise code also is the duplicating of public bipolarity pseudo noise code of emission, but has a sequence displacement of never specifying, the device that is used for handling the said first and second bipolarity pseudo noise codes is arranged, draw a ternary sign indicating number sequence thus and comprise and be used for transmitting and said ternary sequence is made the device of cross-correlation said.

5, a receiver in the claim 4, and have following feature:

Said receiver comprises that several correlation detectors and some devices are used for producing: (1) one first with reference to bipolar sequence one duplicates, and has such sign indicating number displacement, this displacement be in giving a symbol ranges of deciding the transmitter designated displacement and be added in public bipolar code sequence on other correlation detector and diverge to one of a code element less than 1 public mark, (2) one second with reference to bipolar sequence e(t), it is that of this public bipolar sequence duplicates, but has a sign indicating number sequence displacement of never specifying.Each said correlation detector comprise be used for drawing transmitting sequence S(t) with first with reference to bipolar sequence r(t) first device of product; Be used for drawing transmitting sequence S(t) with the second parameter bipolar sequence e(t) second device of product; And the product and second that is used for drawing this first device gained installs the 3rd device of difference of the product of gained; Be used for this difference is carried out the synchronous integration apparatus of integration; Be used for the output of this integrator arrangement is carried out the device of synchronized sampling and can be decided transmitter and carry out the signal processor means that the output of synchronous said correlation detector is handled making said receiver and said giving.

6, the receiver of claim 5, and have following feature: each said first and second device comprises first and second analog multiplexers, and each said transducer has two inputs and an output; Respond said first and second with reference to bipolar sequence r(t) and e(t) after remove to control respectively the device of first and second multiplexers; An and subtraction circuit that is connected on two converter output ends; Said transmitting sequence S(t) is an input that is sent in two inputs of these transducers, and delivers to second input of these transducers by an inverter; Each said transducer can be connected its first input end when its suitable reference sequences has a value to add thereon, and when its suitable reference sequences has second value, connect its second input, the output V(t of subtraction circuit) have following numerical value:

r（t）＝e（t）;V（t）＝0

r（t）＝1，e（t）＝0;V（t）＝+2S（t）

r（t）＝0，e（t）＝1;V（t）＝-2S（t）

7, the receiver in the claim 5 or 6, and have following feature: each said first and second device comprises an analog converter, it has three inputs and an output, said transmitting sequence S(t) be the first input end that is added in said transducer, and be added in second input of said transducer, the 3rd input end grounding by an inverter; And a digital logic arrangement, be used for making transducer work as r(t)=be connected to its 3rd input e(t) time, and as r(t) ≠ e(t) time, be connected to an input in its first and second inputs.

8, any receiver in the claim 5,6 or 7, and and following feature is arranged: each said first and second device comprises that the chain type of the analog converter of a pair of two inputs connects, first transducer has its two inputs, and each inserts a said transmitting sequence S (t) and an anti-phase said transmitting sequence S(t); Said second transducer has its two inputs, each inserts an output of a ground wire and said first analog converter, and digital logic arrangement, be used for the response said two reference sequences r(t) and e(t) after remove to control said first and second transducers, with produce one output V(t):

r（t）＝e（t）;V（t）＝0

r（t）＝0，e（t）＝1;V（t）＝-S（t）

r（t）＝1，e（t）＝0;V（t）＝S（t）

9, any receiver of claim 5 to 8, and have following feature: each said product detector comprises an analog multiplexer, and it has four inputs and an output; Two said input end grounding lines, remaining two inputs respectively connect to such an extent that be used for receiving said list entries S(t) and an anti-phase said list entries S (t), and the device that is used for controlling said transducer, to produce following output signal V(t):

r（t）＝e（t）;V（t）＝0

r（t）＝0，e（t）＝1;V（t）＝-S（t）

r（t）＝1，e（t）＝0;V（t）＝S（t）

10, any receiver of claim 5 to 9, and have following feature: each said first and second device comprises that one is simulated to digitalizer, is used for making transmitting sequence S(t) digitlization; Accumulator that the output of converter is responded and to reference sequences r(t) and the logic device that e(t) responds, as r(t)=counting in this accumulator is remained unchanged e(t) time, and as r(t) ≠ make the counting in the accumulator increase or reduce e(t) time; An output register; Be used for the content of this accumulator is transferred to periodically the device of this output register; And be used for handling the content of this output register and produce a receiver signal of timing error making this receiver be synchronized to the device that this gives selected earlier transmitter.

11, any receiver in the claim 5 to 10, and following feature is arranged: comprise in each said first and second device:

A voltage is to frequency changer;

Be used for drawing transmitting sequence S(t) the device of absolute value;

A forward-backward counter, the output to the frequency translation apparatus responds to voltage for it; And

Digital logic arrangement is used for controlling said reversible counting apparatus, makes this counter:

(a) as r(t)=forbid e(t) time

(b) work as r(t)=0, e(t)=1 o'clock, S(t) be timing counting upwards, S(t) count downwards when negative;

(c) work as r(t)=1, e(t)=0 o'clock, S(t) count downwards, S(t) counting upwards when negative for timing.

12, the receiver in the claim 5, and have following feature:

Have the device that the output to each correlation detector responds, be used for recovering the data of said previously selected transmitter emission.

13, the receiver in the claim 12, and have following feature:

Said Data Recapture Unit comprises the device that is used for storing weighted factor, these weighted factors depend on the special shape that has distortion, and utilize these said weighted factors to amplify the device of said each output of slave receiver, so that signal to noise ratio becomes the best.

14, the system in the claim 5, and have following feature:

A kind of signal to noise ratio method of improving, it comprises the steps: to store the weighted factor that is equivalent to each said correlation detector output and selectes weighted factor by the special shape that has distortion; Amplify these output from the function of next said these weighted factors of conduct of said correlation detector; Merge the output after these said amplifications.

15, the receiver in the claim 5, and have following feature:

Each said correlation detector comprises: the device that is used for producing an in-phase correlate and 90 ° of phase place coherent signals, when said receiver and saidly give earlier selected transmitter when synchronized with each other, in-phase correlate is in greatly, 90 ° of phase place coherent signals are in minimum, and said processing unit comprises: the device of absolute value that is used for drawing the ratio of said homophase and 90 ° of phase place coherent signals, and be used for mobile receiver device regularly, amount of movement is to give selected and that depend on said ratio earlier size, enables to reach synchronous with the said transmitter of selecting earlier that gives.

16, the receiver of claim 15, and have following feature: when giving certainty ratio greater than one, near optimal synchronisation point, sets up the ratio that records a synchronous dead band.

17, claim 15 or 16 receiver, and have following feature:

Said processing unit comprises a kind of storage device, wherein has list data, and these data move synchronization timing to come out as a function definition of said correlation ratio different value.

18, the receiver in the claim 5, and have following feature:

Each said correlation detector comprises the device that is used for producing in-phase correlate and 90 ° of phase place coherent signals, when said receiver and saidly give earlier selected transmitter when synchronized with each other, in-phase correlate is in greatly, it is minimum that 90 ° of phase place coherent signals are in, and said processing unit comprises: with the device of the absolute value of the ratio that decides said homophase and 90 ° of phase place coherent signals; Be used for device that the size of said ratio is compared with a predetermined value, and the device that said comparison means is responded and has signal not to exist under the noise background to differentiate.

19, the receiver of claim 18, and have following feature:

Said processing unit further comprises a kind of device, the signal Synchronization that the size that it just thinks said ratio just makes said receiver go and come in when surpassing said predetermined value is so that said receiver is locked in and saidly gives on the transmitter of selecting earlier rather than be locked on the noise.

20, in direct sequence spread spectrum code division multiplex system, comprise:

A timing source;

Some synchronous transmitters on this timing signal source, and one of every transmitter emission is by public bipolarity pseudo noise code institute expanded data signal, this pseudo noise code are to have to specify and displacement inequality public bipolarity random code sequences all; And

The synchronous receiver on this timing signal source is used for receiving the bipolarity pseudo noise code of giving the sign indicating number sequence displacement of first appointment that has of said emission;

A kind ofly make receiver and said one give the earlier selected synchronous method of transmitter, one of this transmitter emission has the said bipolarity pseudo noise code institute expanded data signal that gives the sign indicating number sequence of first appointment by this.

And with following each step as feature:

Produce one first bipolarity pseudo noise code, it is duplicating of the said bipolarity pseudo noise code of giving the displacement of first designated code sequence of having of this emission; Produce one second bipolarity pseudo noise code, it is the duplicating of bipolarity pseudo noise code of this emission, but has a sign indicating number sequence displacement of never specifying; Merge the said first and second bipolarity pseudo noise codes, draw a ternary sequence; Two condition pseudo noise code and said ternary sign indicating number sequence to said emission are carried out cross-correlation; And result in response, produce a receiver timing signal.

21, the method for claim 20, wherein said treatment step comprises a subtraction.

22, claim 20 or 21 method, wherein said two condition sign indicating number sequence is a maximum length (ML) sequence.

23, claim 20,21 or 22 method, wherein said two condition sign indicating number sequence is a phase shift keying (PSK) signal.

24, be suitable for receiving in the data receiver of the data-signal that comes by a transmitter in some the transmitters, every transmitter is launched one by public pseudo noise code institute's expanded data signal and a signal that comes from the timing signal source, wherein pseudo noise code is the public pseudo-random code sequence that an appointment has the displacement that has nothing in common with each other, a kind of this receiver that makes is synchronized to method for synchronous that gives on the selected earlier transmitter in the said transmitter, one of this transmitter emission has the said pseudo noise code institute expanded data signal that gives the sign indicating number sequence of first appointment by this, and with following each step as feature:

(a) to said data signal samples, sample rate equals frequency or its integral multiple in this timing signal source;

(b) merge one or more data samples that come in succession, produce a data sample point, make it be equivalent to a specific timing point in said timing signal source;

(c) in said data sample point, detect which sample point and have maximum; And

(d) receiver is locked on the timing point in the timing signal source that is equivalent to said maximum value data sample point.

25, in direct sequence spread spectrum code division multiplex system, comprise: a timing source, some synchronous transmitters on this timing signal source, one of every transmitter emission is specified and displacement inequality public pseudo noise code institute expanded data signals all by having; And the receiver of a normal synchronized on this timing signal source, be used for receiving the pseudo noise code that having of said emission given the displacement of first designated code sequence; A kind ofly make receiver and said one give the earlier selected synchronous method of transmitter, one of this transmitter emission is by having the said pseudo noise code institute expanded data signal that gives the sign indicating number sequence of first appointment, and with following each step as feature:

(a) to said data signal samples, sample rate equals frequency or its integral multiple in this timing signal source;

(b) merge one or more data samples that come in succession, produce a data sample point, make it be equivalent to a specific timing point in said timing signal source;

(c) in said data sample point, detect which sample point and have maximum; And

(d) receiver is locked on the timing point in the timing signal source that is equivalent to said maximum value data sample point.

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