CN85105642A - Automatically be identified in the method and apparatus of the modulator-demodulator that responds in the multidrop network - Google Patents
Automatically be identified in the method and apparatus of the modulator-demodulator that responds in the multidrop network Download PDFInfo
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- CN85105642A CN85105642A CN 85105642 CN85105642A CN85105642A CN 85105642 A CN85105642 A CN 85105642A CN 85105642 CN85105642 CN 85105642 CN 85105642 A CN85105642 A CN 85105642A CN 85105642 A CN85105642 A CN 85105642A
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Abstract
High-speed communication system has some far-end modulator-demodulators main and that discerned by coding, the signal that receives from far-end makes primary modem set up and store corresponding with each far-end modulator-demodulator respectively peculiar operational factor rapidly, comprise equalizer coefficients and receiver parameter, they are to obtain when transmitting for the first time advocating peace between each far-end, in transmission subsequently, this particular remote modulator-demodulator is discerned in the transmission specific coding in the time of reserving before the transfer of data, primary modem takes out its receiver of parameter adjustment that in advance obtains according to the identification signal that receives, and begins transfer of data rapidly and need not transmit at every turn and all adopt long training sequence.
Description
The present invention relates to high speed modem, particularly the high speed modem that in the multiple spot polled network is used, is adopted.
In a kind of multi-point communication network, the remote terminal of a plurality of subordinates of main website poll or be slave station.When comprising modulator-demodulator in the telecommunication system, the modulator-demodulator of main website transmits its Zai Bo And continuously and is received by each remote terminal modulator-demodulator, and the remote terminal modulator-demodulator is transferred to demodulating data the data terminal equipment (DTE) that is connected with the data Xie Tiao And that carries then.When corresponding remote terminal ， And of main website poll and polled DTE responded the polling signal from main website, this corresponding far-end modulator-demodulator must at first be connected its Zai Bo And and set up a communication channel to master station.In case this particular remote station modulator-demodulator begins action, the main website modulator-demodulator will detect the carrier wave of far-end modulator-demodulator, extract the timing signal of receiver, inner gain amplifier parameter ， And is set calculates the value of modem equalization device so that this is specificly now compensated with the transmission channel of far-end modulator-demodulator.Like this, because the communication channel of each modulator-demodulator all can have the independent path or the connection of a separation, just caused a different set of response characteristic of respective phase and amplitude, made the main website modulator-demodulator to compensate respectively each modem signal passage.Each main website-remote terminal communication channel all required the modulator-demodulator that connected to begin with the training signal of a sequence, so that essential parameter and the coefficient of corresponding modulation receiver acquisition before each transfer of data.But each training sequence signal has occupied the quite big a part of time, otherwise should the time just can be used to data communication.Carrying out the short time from different far-end modulator-demodulators during transfer of data, the part that is used for the receiver training in the transmission time cost that just becomes is higher, causes the efficient of modem system and whole data network seriously to descend.
Communication system of the present invention comprises a plurality of high speed modems, these modulator-demodulators are connected on the multidrop network with a central primary modem and a plurality of far-end modulator-demods, make system reach maximal efficiency by the communication of promptly setting up between primary modem and the independent far-end modulator-demodulator.System effectiveness is defined as the ratio of actual data transfer time and overall transmission time.The present invention is kept to minimum and increases efficient adjustment or the training time by making the modulator-demodulator subsequent transmission.According to the present invention, primary modem obtains the receiver operational factor in initial training sequence and equalizer coefficients ， And is distributing to parameter and coefficient storage in the memory cell of this particular remote modulator-demodulator subsequently.When the transmission of subsequently modulator-demodulator need to begin to use the coefficient of storage in advance and parameter, the receiver parameter of primary modem and equalizer coefficients are reinitialized to being stored in the value in the corresponding memory cell, are following the receiver adjustment of training sequence to add of having shortened then.According to the present invention, primary modem at first obtains to have improved the above-mentioned parameter and the coefficient of accuracy by the initial training time before the prolongation transfer of data, and the specific receiver parameter of being stored comprises carrier frequency displacement and data ticking frequency displacement parameter.According to the present invention, determine that for each far-end modulator-demodulator an additional Can Shuos that And stores so that use in the future, this parameter makes the receiver markers reach best according to the difference between the different parameters that partly obtain of initial training sequence.In modulation transmission subsequently, corresponding far-end modulator-demodulator is discerned by the cognizance code that is transmitted, and several previously used equalizer coefficients and receiver parameter are restored.After this, primary modem further obtains remaining receiver parameter in a very of short duration training period.The parameter that in of short duration training period, obtains with before Que Ding the And stored parameters and combine, make each far-end modulator-demodulator with the primary modem communication in obtain high data accuracy minimum (of short duration) training period arranged simultaneously, this just makes the transmission of data reach the efficient of Zui Da And raising system in transmission subsequently.
In each embodiment discussed below, the far-end modulator-demodulator is by one that transmits as first data after initial training period clearly digital identification.In the transmission afterwards,, adopt the phasor difference data that the identification signal of the uniqueness sent in of short duration training period by each corresponding far-end modulator-demodulator is encoded according to first embodiment of the present invention.This identification signal also is used to recover the necessary carrier phase information of the normal operation of receiver simultaneously.This specific cognizance code can be 12 in worthwhile one, and this value is selected by a switch in each far-end modulator-demod.This cognizance code is converted into a duration with corresponding proportion by the carrier wave of phasor difference coding.In such a way, carrier wave both can be used for discerning modulator-demodulator, also can be used for making the signal in the receiver part to recover.Training sequence by polled far-end modulator-demodulator transmission is divided into several sections.According to the present invention, recognition sequence presynchronization time (Presynchronization time) with one 14 baud behind the second training sections has one first data value as Kai Shi And at interval.The cognizance code of being followed one period duration that first data value is kept in conduct before the carrier signal that comprises second data value.Primary modem receives training sequence the transmission contain identification signal from the far-end modulator-demodulator.The width of first signal is to determine that De ， And and corresponding code number have also provided.The code number is represented that by tetrad which is carrying out communication to point out 12 far-end modulator-demodulators uniquely.The cognizance code of measuring also is received modulator-demodulator and is used to select a receiver hybrid parameter memory, stores the receiver parameter corresponding to this far-end modulator-demodulator therein.When transmitting data between later primary modem and this far-end modulator-demodulator, training period be shortened And and this code number be used to from corresponding receiver hybrid parameter memory, to detect from correspondence, before the parameter that in advance obtains in the equalizer coefficients of storage and the corresponding receiver parameter.This receiver is Shuoed And according to the Can that detects and is adjusted rapidly by the signal of the training period that shortens, and begins transfer of data then.
Second embodiment adopted before short training sequence with a single-tone or double-tone sequence finish with 12 far-end modulator-demods in the identification of a unique corresponding unit.The frequency of these sounds is within the signal band scope that the transmission of corresponding far-end modulator-demodulator is partly transmitted, And and be detected in the signal band scope that is detected by receiving modem.The identification signal that is produced is used to retrieve corresponding equalizer coefficients and receiver signal by receiving modem, as mentioned above.According to any one embodiment of the present invention, the system and method for far-end modulator-demodulator identification makes homophony system demodulation receiver eliminate long equalizer training process by synchronous rapidly And, makes the effectively quick poll to a lot of far-end modulator-demodulators become possibility.
Above-mentioned and further feature of the present invention will be in conjunction with the drawings, and the detailed description of only reading to example is better understood, wherein:
Fig. 1 is the block diagram of multi-point communication system;
Fig. 2 is the block diagram of a modulator-demodulator in the system shown in Figure 1;
Fig. 3 is the demodulator block diagram of a modulator-demodulator;
Fig. 4 is a sequential chart, has shown the identification of training sequence internal modulation demodulator Audiocode or time width code; With
Fig. 5 is a sequential chart, has shown the position of training sequence modulator-demodulator identification afterwards.
In multidrop network shown in Figure 1, according to the present invention, a plurality of far-end modulator-demodulator of primary modem 30 a polls 21-25.Each far-end modulator-demodulator is connected on the corresponding data terminal equipment 31-35, and same primary modem 30 is connected on the master data terminal equipment 40.Primary modem 30 transmits a Zai Bo And continuously and is received by each far-end modulator-demodulator 21-25 on the connection network.When primary modem 30 transmitted data, each these data of far-end modulator-demodulator Jie Shou And demodulation passed to it corresponding data terminal equipment 31-35 then.Normally in service, a certain equipment in the middle of the data terminal equipment 31-35 will cease the data that respond from primary modem by carrying to write in reply to primary modem 30.In order to accomplish this point, the far-end modulator-demodulator that this is specific, for example modulator-demodulator 23 must at first be connected its carrier wave, and demodulation responds to homophony system with data to send a training sequence ， And.At any one time, have only a far-end modulator-demodulator its carrier wave can be connected in the network.In a kind of like this arrangement, primary modem 30 must detect these carrier waves, extracts timing signal, determines that internal amplifier gain ， And calculates equalizer values and compensates with the different transmission channels to the particular modem of sending signal.The path of each far-end modulator-demodulator will have the different phase places and the deviation of amplitude, and this deviation is proofreaied and correct by the equalizer with one group of special parameter, and these parameters are corresponding to selected transmission channel and affiliated far-end modulator-demodulator.
According to the present invention, each far-end modulator-demodulator 21-25 all provides a unique cognizance code that can be received by primary modem 30, then by this primary modem with specific cognizance code demodulation.In the process of transmission for the first time, primary modem 30 is optionally adjusted modulation receiver and equalizer according to the parameter of determining from above-described initial communication sequence.Receiver parameter that is obtained and equalizer coefficients are stored in a multiple unit to be mixed among the receiver condition memory, and wherein each unit is corresponding to a specific respective distal end modulator-demodulator.Before transfer of data subsequently begins, from the modulator-demodulator that carries out communication receive the other Dai Ma of a Shi And by primary modem 30 with its decoding; Retrieving receiver parameter and balanced device Xi from the receiver condition memory cell corresponding to this modulator-demodulator Shuos And and deposits suitable receiver and equalizer register in.Primary modem 30 is promptly adjusted then, so that transmit with selected far-end modulator-demodulator, has so just eliminated most time of training homophony system demodulation receiver required again.
According to block diagram shown in Figure 2, modulator-demodulator 50 of the present invention both can be used as the primary modem 30 among Fig. 1, also can be used as any one far-end modulator-demodulator 21-25.Yet primary modem 30 as shown in Figure 3, makes it be different from far-end modulator-demodulator 21-25 owing to comprise that in demodulator 100 is mixed a receiver memory 140, and additional memory cell is arranged in this memory, and its operation will be in following discussion.The telephone connection of one four line is connected on a pair of transmission line 52 and a pair of reception line 54; Data terminal equipment (DTE) is connected on the RS-232 line 56.Modem circuit provides the suitable Code And Decode of signal between above-mentioned signal connects.The signal that is transmitted is by being produced by the signal that DTE interface 58 receives from DTE, and this interface provides the digital signal of the specific logic levels of using in the hardware of the present invention.Switch 60 is selected between a figure signal and this digital signal, and figure signal is to be produced by pattern generator 60, and this pattern generator is in order to produce the modulator-demodulator training sequence, data-signal after this training sequence is finished from DTE interface 58.The selected signal that is produced is encoded according to a kind of known pseudo random code by encoder 64, and suitable spectral distribution is provided in modulator-demodulator, can carry out the relevant recovery of quadrature amplitude modulation (QAM) signal by the known technology in this area like this.The signal that is produced is received by modulator 66, and this modulator produces a QAM output according to the control of demodulation processor 100 discussed below, and this processor is as the master controller of modulator-demodulator 50.By transmission filter 68 filtering, provide the signal of its frequency band through restriction from the signal of modulator 66 output, this signal is connected with a pair of transmission line 52 of telephone system by impedance matching transformer 70.
In the modulator-demodulator block diagram of Fig. 2, the QAM signal is received ， And with the reception line to youngster 54 through transformer 72 and carries out filtering by band pass filter 74 from telephone system.Circuit 76 detects a carrier wave, and this circuit indicates to demodulation processor 100 and has a carrier wave that receives.Carrier amplitude through filtering is made And by low pass filter 80 filtering once more by 78 controls of an agc circuit.Then, the signal that is produced is handled by a splitting phase circuit 82, and so that homophase (I) signal and a quadrature (Q) signal to be provided, these signals are received by demodulation processor 100.Demodulation processor 100 comprises that equalizer and reception control circuit ， And will go through referring to Fig. 3 hereinafter.Demodulation processor provides the output of digital signal, and this output is by decoder 84 decodings, the decoding function that this decoder provides with respect to receiving the partly encoding function complementation of the encoder 64 of explanation.The signal that output produced of decoder 84 is and the corresponding signal of data that these data are received from DTE by the transmitter that carries out another modulator-demodulator (not shown) of communication with this modulator-demodulator.Graphic detector 86 by demodulation processor 100 controls detects the figure that is used in the data training sequence, below will further discuss.Decoder output is subsequently by DTE or make the interface 58 of data terminal be converted to the form of RS232, so that deliver on the relevant device of line 56.
More particularly, modulator-demodulator of the present invention provides a kind of method and apparatus that is used for the equalizer of qam demodulator (receiving port) 100 in training plan 3 primary modems 30, And and an initial data transfer are carried out after an initial training sequence as shown in Figure 4 like this, and a very short follow-up conducting sequence as shown in Figure 5 can be used to follow-up transfer of data.In initial training sequence, parametric equalizer and several receiver parameter, comprise corresponding to markers first phase difference parameter △ of the difference between markers first phase τ and the determined different value of τ ' is stored by Huo De And exactly, for use in transfer of data subsequently.In the patent application of submitting on February 22nd, 1984, describe in detail and use stored parameters and coefficient being entitled as " use stored parameters carry out the training of modem equalization device " in advance, comprise a kind of modulator-demodulator that △ trains.
The size of difference or adjusted value △ is that the function ， And of transmission line characteristics can change with the distribution of dial-up telephone line.According to the present invention,, determine that difference △ is the key of this equalizer training success comprising equalizer with the tap that distributes constantly by the T sampling.
The method according to this invention, equalizer coefficients discussed below, the ticking frequency skew, carrier frequency shift, and markers first phase difference △ parameter all is stored in an initial data transfer process in the discrete cell of mixing receiver situation memory 140, this initial data transfer comprises an initial training sequence, the cognizance code that this unit receives the decode with respect to the far-end modulator-demodulator.Subsequently, when reusing this data channel, this particular modem is identified; And recovers corresponding receiver and parametric equalizer and markers first phase difference △, uses the logical sequence of a short circuit to recover this first phase of an initial markers first phase τ (in a preceding program process) once more and is added in difference △ upward so that the first phase τ ' of correction to be provided.The carrier phase parameter of modulator-demodulator also all the other during this Short Training partly in, recover before the transfer of data subsequently.
Initial training sequence as shown in Figure 4, comprise a preorder part that has strong spectrum component at band edge, τ promptly is from wherein acquisition, and following a length thereafter is enough to gradient method the pseudo-random signal of equalizer training with a definite correction first phase τ '.Initial training preorder is partly looked is enough to intactly obtain the ticking frequency displacement, and the school becomes markers first phase τ ' to measure (as discussed below) exactly by Jian Dan And during pseudo-random signal like this.When communication subsequently, obtain first phase τ once more, then △ is added to first phase τ and goes up recovery correction first phase τ '.Because the equalizer coefficients of selecting during beginning is the markers first phase of adjusting at by difference △, receiver reaches optimum state rapidly after the Short Training phase subsequently.Consequently, the present invention allows remarkable connection sequence that shortens of use in transfer of data subsequently, and low error rate and minimum additional firmware are provided, and the apparent receiver adjustment required time of saving kindly.
Except with τ and △ and the operation relevant with the storage of parameter and coefficient, total operation is described below.From transmission channel, the signal that receives as telephone wire 54 carries out amplitude rectification ， And by band pass filter 80 filtering by automatic gain control (AGC) circuit 78, and this filter eliminates the frequency band external noise.The signal that is produced is received by a sampler 102, and this device provides the sample of signal speed of per second 1/S.Selected speed 1/S equals signal integral multiple m/T(m=4 in the present embodiment of (baud rate) 1/T constantly), with this sample of signal that some is provided in the output of sampler 102, making the sample of signal sequence is that the signal that received (this signal after detection by the dn representative) is described in the processing subsequently of following explanation fully.Then, signal is received by Hilbert transducer (Hilbert transformer) 106.The Hilbert transducer is on record a kind of device with a signal input and two orthogonal signalling outputs, provides the homophase and the quadrature component of input signal respectively at its output.
Homophase (I) and quadrature (Q) output signal from Hilbert transducer 106 are taken a sample with the signal frequency of 1/T by I and Q sampler 108 and 110 respectively.Connect the Shu that a clock markers recovery device 112 is used for receiving analog-digital converter (ADC) 104 and go out Xin And control sampler 102, I and Q sampler 108 and 110, and other parts (not shown) of receiver 100.Above-mentioned each sampler, ADC, AGC and clock recovery device all use by well-known mode, the concrete use of each isolated system are not gone through at this.
Respectively the output in the sampler 108 of received signal and 110 provide, digitized I and Q signal component be added in the signal input part of a complex demodulation device 114.Complex demodulation device 114 receives a homophase carrier wave and the quadrature carrier that form is Sin2 π fcnT that form is COS2 π fcnT from a local signal source, and wherein fc is a carrier frequency, and n is a positive integer, and span is to infinity from zero.If signal is in signal nT reception constantly, be expressed as rn, the output in sampler 108 and 110, I and Q component are expressed as ri respectively, n, and rq, n.Then demodulator 114 provide respectively restituted signal Xn corresponding to I that has taken a sample and component Xin and the Xqn of Q.Plural then Xn is by a plural equalizer 116, and this equalizer comprises a known tapped delay line in the industry.The delay line signal Bei Jia Quan And that receives from N tap sues for peace to produce a signal according to complex operation, and wherein the weight coefficient of N tap is to be stored in the equalizer, the plural number of the feature of expression equalizer 116.
Then, the output signal yn of the plural equalizer 116 that is produced, comprising in-phase component yin, quadrature component yqn, phase difference θ between this machine clock frequency fc and the carrier frequency that received is adjusted according to the output φ of carrier recovery circuit by circuit 118, this circuit with complex signal yn anglec of rotation θ to produce phase-locked plural equalizer output signal y ' n.At last, enter error determinating circuit 120 through output signal y ' n balanced and rotation, this circuit has two kinds of working methods.When data mode, which complex signal what error determinating circuit 120 was determined to be sent here by far-end conveyer (not shown) is, calculate the apparent error signal of corresponding plural number then: e ' n=y ' n-dn, this signal is received by equalizer 116 by rotating element 121 rotation backs.In training method (equalizer is initially adjusted) process, send known, predetermined data-signal in the initial training sequence of conveyer before data, these signals also produce ， And as signal dt, wherein dt=dn by a training control circuit in the receiver 122 simultaneously.Calculate error signal e ' n, use it for the tap coefficient ck that adjusts carrier recovery circuit 124 and adjust equalizer 116 then.Complex signal dn is corresponding to the transmission data, and And is converted to a serial numerical digit (bit) stream subsequently in data output circuit, send to the user.Receiver parameter of being recovered and equalizer coefficients are stored in the far-end modulator-demodulator that transmits with main receiver 30 and mix accordingly that units corresponding Nei ， And discerns according to embodiment of the present invention discussed below in the receiver situation memory.
The initial adjustment of receiver 100, the particularly adjustment for markers first phase τ and difference △ are described as follows: a far-end transmitter (not shown) sends out very simple first sections that has the signal preamble 152 of strong spectrum component in the band edge of transmission spectrum.Agc circuit 78 among Fig. 2 is in fast reaction when initial, and high-gain Zhuan Tai And is that receiver 100 is set up the appropriate signals level rapidly.The appearance ， And that the carrier recovery circuit 124 of receiver 100 detects the received signal energy makes receiver 100 its initialization of beginning and has the training process that triggers sequence, and this will discuss referring to Fig. 4.Markers restore circuit 112 uses strong band broad edge spectrum component to finish initial the determining of best sampling markers first phase τ.Carrier recovery circuit 112 also can be preset at this carrier phase and frequency constantly, though Zhong a QAM Xi Tong with plural equalizer And do not require must be like this because plural equalizer itself just can obtain carrier phase.Then, the far-end transmitter is changed into a pseudorandom training waveform 154 that is used to train equalizer among Fig. 4 according to the normal signal sequence in the initial training sequence.Sampling markers first phase τ is corrected in pseudo random sequence, so that a new sampling markers first phase τ ' to be provided, equalizer coefficients and this markers first phase are complementary one to one, and difference is △, this difference also is that unique De ， And is stored in respectively in the memory 140 to each far-end modulator-demodulator.
The sampling markers first phase τ ' that proofreaies and correct provides the basis of the efficient sampling data frequency response of a definite passage.For this reason, equalizer is through training, so that this passage is compensated.The one group of trained best equalizer coefficient that is produced is present in the end ， And of pseudo random sequence and the correction sampling first phase τ ' of each far-end modulator-demodulator is complementary one to one.According to the present invention, the correction markers first phase τ ' of this each far-end modulator-demodulator and the man-to-man coupling of equalizer coefficients all are kept in the independent unit of memory 140 uniquely by calculating and the storage of difference △, to allow short conducting sequence subsequently, be called " Short Training row ", be used for further transfer of data on the same transmission circuit.
Phase-locked loop, particular as receiver 100, among the markers and the carrier recovery loop of markers restore circuit 112 and carrier recovery circuit 124, its derivative term that is higher than single order generally requires a lot of symbol periods in the initial training sequence, so that accurately obtain this derivative term.In the present invention, the details of phase-locked loop is not a key factor to the application of △, does not comprise these details at this.In the initial training sequence, these derivative terms also are stored in corresponding to ， And among the memory 140 of each far-end modulator-demodulator and recover to reduce or eliminate the time that regains them in the Short Training program.Therefore, in comparatively desirable embodiment, skew of receiver ticking frequency and carrier frequency shift, do not hold the first △ of differing of acquisition to be stored in the discrete cell of memory 140 with equalizer coefficients with in initial training, be used to recomputate correction markers first phase τ ' (obtaining after the τ when short training sequence subsequently begins).Then, when the logical sequence of short circuit begins, according to receiving the data that the decoded far-end modem code recovery of De, And is stored.
Figure 4 shows that sequential chart according to initial training sequence of the present invention.152 representatives during this time have the preamble of strong spectrum component at band edge, make during T
1In obtain rapidly markers first phase τ ， And and make the signal data that obtains ticking frequency skew and carrier frequency shift.In comparatively desirable embodiment, time T
1Length be limited in the possible shortest time, in this time by the markers restore circuit between the sign field T ± can repeatedly obtain markers first phase τ in 2% the scope.152 total duration T during this time
2, be typically two seconds, be enough to obtain fully the ticking frequency skew.Equally, carrier frequency shift also can during obtain in 152.During this time 153, typically be one second, representative is used for the pseudo random sequence that equalizer training and carrier phase are obtained.During 153 when finishing, markers first phase τ has been corrected for τ ′ ， And and difference △ is determined and stores.
Directly follow after initial pseudorandom data training sections 153 and transmit a modulator-demodulator identification number 154, just in time be before actual data transfer begins, this identification number is used for being chosen in the unit 1 that mixes receiver situation memory 140 by training method control circuit 122,2,3, N has the parameter and the coefficient value of modulation receiver (demodulator) 100 in this memory.
Training method control circuit 122 is receiving the initialize signal that is entered by carrier detecting circuit 76 response after the signal that produces, and the number of times of data symbol is calculated.The Shuo of enough number of times is taking place according to Fu And and elapsed time T
2After, an incident TS takes place by the training method control circuit
1, the 126 quilt recoveries of markers adjustment counter are zero in this circuit, and T allows to carry out the increment variation according to the markers restore circuit between sampling period, and this markers restore circuit rises in value or depreciations markers adjustment counter 126.When the markers restore circuit caused the increment response of a growth in the T between sampling date, markers is adjusted counter 126 countings to be increased.When causing the decrement response of a growth in the markers restore circuit is between sampling date, markers adjuster counter 126 countings reduce.
For during the situation of a given ticking frequency skew obtaining in 152, markers restore circuit 112 will during the skew of the adjustment separate compensation ticking frequency of a fixed number of instruction in 153.(optimized) markers first phase τ ' of a correction during any other adjustment all is attributable to during 153.In time T
3During termination, the training method control circuit will be enough to train the equalizer coefficients of the equalizer (with obtaining carrier phase) that is adopted, carrier frequency offset and ticking frequency deviation are stored among the mixing receiver situation memory cell that numeral that the Shen receives in during 154 indicates.Then, training method control circuit 122 becomes ticking frequency shifted signal data transaction in whole duration T
3On markers adjust an equivalence numeral of increment, and revise the counting output that markers is adjusted counter 126, adjust the numeral of increment to determine markers, this increment comprises markers first phase difference △.Then, difference △ is stored in the discrete cell 1,2,3 of mixing receiver memory 140 ... among the N, for use in the triggering of Short Training row.Must be offset to obtain ticking frequency by long enough (typically being two seconds) during 152, like this, the equivalent number that is transformed into markers adjustment increment can have enough resolutions, can accurate Calculation difference △.
Figure 5 shows that the basic system and method for identification modulator-demodulator in the Short Training row at interval, wherein identification is to be determined by the time interval between specific data signal or the vector.According to one one embodiment, recognition sequence occurs in after the sections 202 of training sequence and before the data.According to system of the present invention, be with two or dibit (dibit) transmission in pairs for each baud wayside signaling.At the end of sections 202, the value 0 ,-1 of an I and Q will be transmitted in the presynchronization interval 203 of one 10 to 14 baud.This time interval is detected between two prearranged signals, the directly transmission after presynchronization signal 0 ,-1 of first signal.First signal 204 is included in a signal 0 ,-5 that transmits in the duration of about 4 bauds.This signal is received and is surveyed by demodulator, and this demodulator will be exported filtering and provide a filter response, and its signal transition is detected according to the peak value of filtering signal then.The interval of representing coded identification signals by first and subsequently signal peak determine.Because signal filtering blured the accurate transit time relevant with signal specific, the constant offset interval of one four baud is added in initial signal 0, after-5 so that the filtering detection signal decay to one be convenient to input than low value.After this, system wait from 0, and-5 to 0 ,-1 transformation, this transformation have produced the secondary signal of limiting time sections ending.This transformation can be directly takes place after the interval of first four bauds signal 0 ,-5, and perhaps extensible X(counts arbitrarily) interval of individual baud.Then, identification is directly determined according to the X number relevant at interval with the duration of being determined by identification markers element 130.Because this method requires to recover baud markers and carrier phase, this identification sections must occur in after the sections 2.Say that sections provides the necessary synchronous and parameter adjustment of receiver.
Second method according to identification modulator-demodulator of the present invention is also shown in Figure 3, adopt identification 201 codes of audio coding, receiver further comprises the zero crossing detector 90 of an outside, as shown in Figure 2, or the zero crossing detector within receiver 100 132, produce the one-period signal according to zero crossing by automatic gain control section 78 signal that produces.The discrete cell that this signal is received with selection memory 140 by storage multiplexer (MUX 134 is then therefrom retrieved receiver parameter and equalizer coefficients.Determine received characteristic frequency with this periodic signal then.Shown in the typical frequencies table of using in this method 1 below:
The modulator-demodulator hertz
1 696.77
2 780.72
3 875.67
4 967.16
5 1062.30
6 1178
7 1296
The modulator-demodulator hertz
8 1440
9 1620
10 1851.43
11 2160
12 2492.31
More than using in the embodiment of listed 12 audio frequency, each in 12 audio frequency is all corresponding to a specific modulator-demodulator; This audio frequency is by the decoding of the microprocessor in the demodulator 100, to produce a relative unique discre value.Listed audio frequency is to select according to following principle in the above table 1.For the ease of improving noise immunity, and reducing the mistake that from telecommunication transfer error, produces than the arrangement of bass, this mistake generally can reach ± deviation of 10Hz, add that attached group postpones.High audio is restricted to 2500Hz, and this is the logical peak frequency that holds easily of band of system.Then, Zhong Jian audio frequency is to select downwards from the upper limit of 2500Hz.Processor 106 comprises a counter or timer, and it detects the periodic signal that is produced by zero crossing detector 90, produces the identification signal corresponding to this frequency.
The recognition methods of an alternating frequency selection comprises the sequence of one two groups different audio frequency, and first is four and selects in the audio frequency that second portion subsequently is to select one in three audio frequency, and 12 possible combinations are provided.The sequential of tonic train shown in Fig. 5 201, first sections of its sound intermediate frequency directly occur in before second sections 202 of training sequence.First tonic train is to select one from four frequencies, and this frequency generally is in shown in the table 1 within the frequency range, but is not one that is necessary in the middle of 12.Second group of audio identification frequency adds that with first (base) frequency a deviation frequency is relevant.Deviation frequency can be zero, adds a fixed value or deducts a fixed value, and this value generally is less than the interval of facing fundamental frequency to the next one mutually.After a limited time, begin second audio identification.If group postpones serious, between the tour that occurs between first and second frequency identification, can be delayed and reach two milliseconds, otherwise just fuzzy, the detection difficulty that identification signal is changed, and it is uncertain or inaccurate to cause that second frequency is identified as.By from the fixing slight deviation of fundamental frequency, in phone transmission known because group postpone the error that produces will be very little and can determine frequency exactly by the zero cross detection method with respect to fundamental frequency.According to one embodiment of the present invention, in two-part audio identification sequence, this sequence typically continue one 10 milliseconds during, after first 2.5 milliseconds, will detect carrier wave.
Above exemplary, and the modification of having been done by the skilled person in those this areas and replacing all within the scope of the present invention, except appended claim, the present invention is not limited by other.
Claims (9)
1, in multidrop network, a kind of automatic identifying method comprises the steps:
Select one first training sections;
Receive above-mentioned first sections;
Set up a carrier frequency;
Send one first identification sections;
Receive the above-mentioned first identification sections;
Send data; And
Receive data.
2, the method for claim 1 further comprises:
Send one second cognizance code; And
Receive one second cognizance code.
3, the method for claim 2 further comprises:
Send one second markers sections signal; And
Receive this second markers sections signal.
4, in a multidrop network, a kind of automatic identifying method comprises the steps:
Transmit one first and second sections;
Receive the above-mentioned first and second markers sections;
Receive one first identification signal;
Sending one second identification signal corresponding to the station after the identification duration;
Receive above-mentioned first and second identification signals;
Detect the duration between first and second identification signals; And
Determine to discern according to the above-mentioned duration.
5, in a multidrop network, a kind of method that recognizes the far-end modulator-demodulator of primary modem comprises the steps:
Transmit one first and second markers sections;
Transmit one first identification signal; And
After a duration, transmit one second identification signal corresponding to far-end modulator-demodulator discriminating digit.
6, in a multidrop network, a kind of method that recognizes the far-end modulator-demodulator of primary modem comprises the steps:
Receive one first and second markers sections;
Receive one first and second identification signal;
Detect the beginning of each above-mentioned first and second identification signal; And
Determine identifier according to the time that continues between the beginning of the beginning of first identification signal and second identification signal.
7, in a multidrop network, a kind of method that recognizes the far-end modulator-demodulator of primary modem comprises the steps:
Transmit one first training sections;
Transmit one have with the corresponding audio frequency of identification number first identification audio signal; And
Transmit one second audio signal.
8, in a multidrop network, a kind of method that recognizes the far-end modulator-demodulator of primary modem comprises the steps:
Receive one first audio signal;
Receive one first identification audio frequency;
Detect the frequency of this first identification audio frequency;
Frequency according to this identification audio frequency is determined identification number; And
Receive one second audio signal.
9, in a multidrop network with quadrature phase shift keying data, a modulation-demodulation device comprises:
Audio decoding apparatus provides a corresponding signal of the frequency with received signal; And demodulating equipment, receive quadrature phase shift keying data-signal and this audio decoder output signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 85105642 CN85105642A (en) | 1985-07-24 | 1985-07-24 | Automatically be identified in the method and apparatus of the modulator-demodulator that responds in the multidrop network |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 85105642 CN85105642A (en) | 1985-07-24 | 1985-07-24 | Automatically be identified in the method and apparatus of the modulator-demodulator that responds in the multidrop network |
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| Publication Number | Publication Date |
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| CN85105642A true CN85105642A (en) | 1987-01-28 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN 85105642 Pending CN85105642A (en) | 1985-07-24 | 1985-07-24 | Automatically be identified in the method and apparatus of the modulator-demodulator that responds in the multidrop network |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1110916C (en) * | 1996-03-27 | 2003-06-04 | 罗伯特·博施有限公司 | Point-multi point radio transmission system |
| CN111263205A (en) * | 2020-02-28 | 2020-06-09 | 青岛海信宽带多媒体技术有限公司 | Identification method, driving method and device for front end component of terminal equipment |
-
1985
- 1985-07-24 CN CN 85105642 patent/CN85105642A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1110916C (en) * | 1996-03-27 | 2003-06-04 | 罗伯特·博施有限公司 | Point-multi point radio transmission system |
| CN111263205A (en) * | 2020-02-28 | 2020-06-09 | 青岛海信宽带多媒体技术有限公司 | Identification method, driving method and device for front end component of terminal equipment |
| CN111263205B (en) * | 2020-02-28 | 2021-12-24 | 青岛海信宽带多媒体技术有限公司 | Identification method, driving method and device for front end component of terminal equipment |
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