CN1003271B - Method and apparatus for telephone exchange system synchronize - Google Patents

Abstract

The present invention discloses a method and equipment thereof for synchronizing digital signals from a first place (such as a digital telephone station) and the digital signals of a second place (such as a public equipment interface of a telephone switching system). The data signals transmitted from the first place are received from the second place, the occurrence of the data signals is judged at selected time, and subsequent delay time is selected in the first place. When delayed data signals occur in the second place at the selected time, the delay time of the data signals detected for the first time and the last time in the second place is averaged so as to determine optimal delay time, and a digital code which is corresponding to the optimal delay time is transmitted to the first place for selecting the optimal delay time of the first place.

Description

The method for synchronous and the equipment that are used for telephone switching system

The present invention relates to the synchronization scenario in telephone switching system, refer more particularly to a kind of method and apparatus that makes the time reference of the common equipment unit (CEU) that the digital data signal from telephone stations that receives is synchronized with a telephone switching system.This telephone stations is connected to this CEU as a keying operation unit (KSU).Because, through the telephone stations transmission line with transfer of data to the telephone stations that is positioned at a distant place or to send the time-delay that is run into therefrom here be variable, so such be necessary synchronously.

In order to be that benchmark carries out synchronously all, just must provide a kind of device that is used for compensating the outside time-delay that is run into from the data of digital telephone with timing at CEU or KSU place.A phone can be installed in the place different apart from KSU, and it can run into because the time-delay that propagation delay caused of transmission medium.For the twisted pair of standard, the propagation delay of per thousand feet cables is about 2 microseconds, and therefore, if the position of a phone is 2,000 feet from KSU, it will run into the loop time-delay (to phone 2 microseconds, returning 2 microseconds) of 4 microseconds.In order to compensate these time-delays, just need a kind of this amount of delay that be used for determining, and the method and apparatus that this time-delay is compensated.

An object of the present invention is to provide a kind of method and apparatus, be used on the time reference from the common equipment unit of data sync to a telephone switching system of a digital telephone stations.

Another object of the present invention provides a kind of method and apparatus, is used for compensating in telephone transmission line because the hysteresis of the signal phase that propagation delay caused.

In addition, also has a further purpose, just provide a kind of like this method and apparatus, it can be applied in the digital telephone exchange system, and the speech information of this system between telephone stations and common equipment unit transmits with digital form, for example PCM(pulse-code modulation) data.

These and other purpose system of the present invention realizes by synchronizer, and this device is synchronous with the data-signal in a digital data signal that has been transferred to certain second place from certain place and second place.This is included in first place and is used for a digital signal is transferred to the device in second place; Be used for the data-signal receiving system whether decision data signal occur a selected time in second place; Be used for coded data is transferred to the device in first place in second place; In first place in order to change the device of delay time to coded data response, promptly be transferred to second place at this time-delay back data-signal, thereby, when the device that is used for judging in second place in selected time detecting when having data-signal to occur, transmitting device just is transferred to coded data first place, go to select the delay time value, the result, this data-signal in second place just occurs in the selected time.

According to equipment, its method has also been done introduction.Other purpose of the present invention, characteristics and superiority also will be found out from following detailed description.

In the detailed description below, will with reference to the accompanying drawings the present invention be carried out more detailed introduction, in the accompanying drawings:

Fig. 1 is one and is illustrated in the calcspar that connects between the common equipment unit of some digital telephones and a telephone switching system.

Fig. 2 is that the telephone stations interface of this common equipment unit is than detailed block diagram.

Fig. 3 be one of them digital telephone platform than detailed block diagram.

Fig. 4 is one and is illustrated in the sequential chart that the method for phase lag is determined to cause owing to transmission line in the common equipment unit.

Fig. 5 illustrates by the common equipment unit the data placement form of data to telephone stations.

Fig. 6 illustrates the data placement form that is transferred to the signal of common equipment unit from telephone stations, and

It is a program flow diagram that Fig. 7 A and 7B join, and it can leave in the program storage of a common equipment cell phone platform interface, is used for determining the hysteresis of phase place and it is compensated.

Now referring to accompanying drawing, Fig. 1 is illustrated in a common equipment unit 10(CEU) the mutual basic contact of (as the keying of keyphone switching system operation unit (KSU)) and a plurality of digital telephone 50, KSU10 comprises telephone office's interface 11 of linking data line 8, and this transmission line 8 is linked KSU with phone; Also comprise a trunk interface 9, this interface is linked KSU in the circuit of outward trunk or main exchange (C, O), digital telephone 50 is adaptive mould/number and D/A, it converts voice signal to digital form, to be conducted to the transmission of KSU signal, be used for receiving digital signal simultaneously, and convert it to analogue voice signal from KSU.

Fig. 2 is illustrated in relevant circuit in telephone office's interface 11 of KSU10.This telephone office comprises a receiving interface 12, this interface comprises reception isolation circuit 13 and the multiplexer 14 that is used for each passage, this transducer will and the multichannel compound series signal that circulation distributes between changing on time from the mass data of 16 stand-alone phone offices 50 as shown in the figure, the serial signal output of multiplexer 14 is postponed by a constant time lag level 16, be time-delay 96 microseconds in the specific embodiments as shown, the output of delay line 16 passes to an input of digital audio processing machine 18 and sign register 20 then, Audio Processing machine 18 and sign register 20 are under the control of the cpu central processing unit 22 of telephone office, as the Z80 microprocessor of being made by zilog company.Be coupled to the signal of sign register 20 and Audio Processing machine 18, must be synchronous with the system time reference that produces by time reference generator 24, and this time benchmark is by a clock signal of system control.

The data/address bus 26 of sign register 20 process CPU is used in two aspects by the CPU22 of telephone office; Promptly read from what telephone set came and be inserted into the signal control data the serial signal and signal control data write among the serial signal row, this serial signal warp 28 is exported to telephone set.

Audio Processing machine 18 is revised the Audio Meter gain with digital method, these audio signals are from linking receiving interface 12(line 29) telephone set and come other digital signal 30 of coming since the system digits data/address bus, these audio signals or derive from other telephone set of other telephone office's interface in the system of linking, or deriving from external interrupt line C, O, these signals are synchronous with system time reference 24.In illustrated specific embodiments, system time reference is by the decision of the sampling rate of the PCM signal on the digital data bus, this speed is that 8 kilo hertzs of suitable sampling periods are 125 microseconds, therefore, if the two carries out strict decoding to signal by Audio Processing machine 18 and sign register 20, then just must be synchronized on the cycle of 125 microseconds from the signal that above-mentioned phone is come.

Along with the two is handled from the data 30 of digital data bus with from the data 29 of above-mentioned telephone set by 18 pairs in digital audio processing machine, be transferred to the data 32 that phone drives and be sent to multiplexer 34.In 34, be inserted in the data 32 from the signal control data in the sign register 20.The demultiplexer 36 that mixed digital voice and signal data are sent to coffret 38, and separated signal is linked each telephone set through isolating circuit 40, as shown in the figure, two telephone offices can utilize a special encoding scheme, so that can use a common data transmission channel jointly.

Received from telephone set and by Audio Processing machine 18 data processed, warp 42 returns links digital data bus, to be transferred to other telephone set or external interrupt line in the system.

Be used for control audio processor 18 operation and determine and program that compensation of phase lags behind leaves in the program storage 44 that this memory is linked CPU22, this program will be described in more detail according to Fig. 7 A and 7B.

The block diagram of a digital telephone 50 is shown in Fig. 3.Receive (R _z) form of (relevant with phone) digital data stream is shown in Fig. 5.These Rx data are bi-phase modulated, and have comprised the PCM data and the signal control data that insert.Signal data and PCM data are inserted at 1 ms interval place, and per 1 millisecond of 1 numerical digit by signal data of the least significant digit of pcm word sign indicating number is replaced.Signal data information is that 32 numerical digits are long, and per 32 milliseconds of synchronous time marks of sending a signal are with synchronous with the telephone time benchmark.Usually in the two-phase transfer of data, the frame synchronizing signal of sending never occurs, and promptly in the centre of this one-digit time, data transmit under the repressed situation, have hindered bi-phase modulated.Shown in the interval among Fig. 5 51.Frame synchronizing signal comprises half digit interval of a level 52 as shown, and then is the interval of the anti-phase level 53 of two continuous numerical digits, as shown in Figure 5.

Still according to Fig. 3, digital telephone 50 comprises a receiving interface 56, is used for receiving the data from KSU telephone stations interface.A phase-locked loop 58 is used for extracting a clock signal from the biphase modulated signal that the KSU shown in Fig. 5 comes.Suitable gate circuit 60 extracts the frame synchronization markers from receive data.These signals are used to the time reference 62 of the system that produces respectively and make this time reference synchronous.Time reference 62 is used to make sign register 64 synchronous, makes it not hold the signal data that occurs 32 numerical digits in this register at per 32 millisecond period *.The existence of frame synchronizing signal resets local call time reference 62, thereby phone is calibrated the data flow of the Rx that comes.Behind the calibrating telephone time reference, just can produce time synchronisation, correctly receiving the PCM data, and per 1 millisecond of insertion signal data that extracts a numerical digit, this is by square 63 expressions.Signal data is existed in the sign register 64, up to each frame signal in the cycle (32 milliseconds) deposit 32 signal numerical digits in.Under the direct control of KSU, these signal numerical digits are used to control the state of various telephone lines.

The data that receive also are sent to audio frequency processing circuit 66, there the voice data of PCM are handled.

As shown in Figure 3, move, cancelled 5 numerical digits that receive by KSU, and keep 27 numerical digits and finish other function, as make light-emitting diode flash in order to compensate different lagging phases.

Shift register 68 addressings of numerical digit to a variable word length are controlled in these 5 time-delays, and this shift register compensates time-delay.Basically, this shift register is one many outputs shift register separately, and these are selected by 5 numerical digits of addressing separately.Multiplexer 70 will be from the digital audio signal of voicefrequency circuit 66 with from the signal control data coupling of signal scanning circuit 72.The button of 72 pairs of phones of scanning circuit scans, and moves to determine whether these buttons, and produces a serial that is inserted in the digitized voice signal, exports and deliver to multiplexer 70, and with notice KSU, for example which type of key is pressed.And point out to require which type of function and conversation to get in touch.

The scanning phone is controlled by local time reference 62, and the result just will scan and the synchronization of data streams that receives.32 of controlling in the numerical digits of output are decided to be synchronous numerical digit, and it is always maintained on the identical logic level, shown in 71.Then, bipolar modulated device 74 and coffret 76 are linked in the output of the shift register 68 of variable word length.Bipolar modulated device 74 will become form as shown in Figure 6 from the data-modulated of shift register 68.

As mentioned above, variable word length shift register (VLSR) is a register that all has the addressable parted hair in output place of every grade of register.By selecting appropriate parted hair, can change the time-delay between output and the input.In illustrated specific embodiments, this VLSR has 32 grades, and at 1 microsecond interval to these register timing.32 parted hairs can be selected by the control of one 5 numerical digit address, are the time-delay of 0～32 microsecond scope of incremental change so just can realize 1 microsecond.As mentioned above, 5 time-delay address numerical digits are to obtain from the output of sign register 64.

The data of delivering to KSU from phone also comprise PCM data and signal data, and inserted mode is similar in appearance to the Rx data; Promptly at the least significant digit bit position of per the 8th pcm word, every millisecond transmits a signal numerical digit.Yet in form as shown in Figure 6, data-modulated is ambipolar.

For will be synchronous from the time reference 24 of the telephone stations interface of the data flow of phone and KSU, the process of a software control of employing is correspondingly adjusted the time-delay of variable word length shift register, time-delay with compensation circuit, program is stored in the memory 44, and program flow diagram is shown in Fig. 7 A and the 7B.As mentioned above, a numerical digit in phone (Tx) signal is used for the data flow from phone is harmonized according to the time reference of KSU telephone stations interface as the mark or the synchronous numerical digit of a signal.When the phone needs were synchronous, the PCM signal was suppressed, and telephone stations interface CPU22 position searching data by synchronous numerical digit in sign register 20 flows.This process is shown in Figure 4.Be 64 transmission of the sign register in phone, telephone stations interface CPU22 is that a count of zero is monitored signal from telephone set then to determine the appearance of synchronous numerical digit at first with the time-delay number of addresses position in the sign register 20.If synchronous numerical digit do not occur in certain time interval, then under software control, CPU is the time-delay cyclic address change of VLSR68 just.So, in from the data flow of phone, just increase the additional delay of 1 microsecond, and once more data stream monitored, with the synchronous numerical digit of determining in sign register 20, to occur on the appropriate location.If this numerical digit do not occur then continue to increase time-delay, till detecting synchronous numerical digit and occurring with the incremental change of 1 microsecond.Express among Fig. 4, in sign register 20, synchronously numerical digit near and by its situation of suitable position, the diagram counting is 20～26 microseconds.When the time-delay counting equals 23 microseconds, detected synchronous numerical digit, as shown the number of samples position is set to 1.This time-delay counting is stored, and still continues to increase its counting, no longer occurs up to synchronous numerical digit, and counting is 26 microseconds as represented.Then, this program calculates one and is about and the corresponding time-delay mean value in synchronous numerical digit center, and as shown, a time-delay counting equals 24 microseconds.This counting is in order to the optimum delay value to the phone data sampling; Be transferred to telephone set with binary form and the corresponding to deferred address numerical digit of this time-delay optimum value,, till again new desynchronize occurring, at this moment, repeat said process again with to the VLSR68 addressing.

So,, can the time-delay on the transmission line that connect phone and KSU telephone stations interface be compensated by a variable time-delay that is provided with in telephone stations.For example, under the situation that through total transmission delay of transmission line is 7 microseconds, (spread out of and return each 3.5 microsecond), in telephone set, should adjust to the time-delay of one 24 microsecond.In KSU telephone stations interface, delay-level 16 realizes the time-delay of 96 fixing microseconds, to reach total time-delay of (96+7+24) microsecond or 125 microseconds.Because the time reference of KSU is latched in the sampling period of the PCM data of 125 microseconds, just must delay time 125 microsecond blanking times or its integral multiple with synchronous with time reference at the signal that delay-level 16 outputs place are received by telephone stations.

Flow chart in order to the synchronization program of realizing Variable delay has been shown among Fig. 7 A and the 7B.The per 32 milliseconds of execution of this synchronization program once, a program frame equals 32 milliseconds.According to these accompanying drawings, it is synchronous that the first * of CPU determines a SYNC(whether occurs 100 earlier) numerical digit.If the SYNC numerical digit does not occur, program circuit just points to the B of 7B.Carry out an inspection 102, determining, whether corresponding to 4 32 milliseconds program frame, promptly 128 milliseconds during, the SYNC numerical digit is 0 always; If not zero, then program stops and to turn back to START(initial), to begin next 32 milliseconds program.In case through 4 frame SYNC numerical digits is zero, carries out an inspection 104, to determine that whether telephone device is in the past in synchronous regime.Suppose it is like this, promptly asynchronous for NOSYNC(this moment in 106 expressions) shape knows, then, to be adjusted into 0 at 108 program state counter SF, the address that to delay time at 110 phase counter PHASE(VLSR) adjusts to 0, and is zero 112 with PHASE(this moment) be transferred to telephone stations, turn back to START then.

In next program frame, check the SYNC numerical digit once more 100.As detecting, then lead to B less than the SYNC numerical digit.Program is checked whether passed through 4 frames to determine it, and never detected the SYNC numerical digit again.Remain zero if passed through 4 program frame SYNC numerical digits, then reexamine sync state 104.Owing to be expressed as the phone hold off in the past, then will have entered decision block 114.At this position detection SF counter.If transferred to 0 before the SF, just mean and detect numerical digit always less than SYNC, then program jump is to step 116, and in this position, the PHASE counter increases by 1.Check 118 whether reached the long delay of 31() to determine PHASE.If do not reach, this PHASE value after then increasing just is transferred to the telephone set at step 112 place.If PHASE has reached 31, PHASE is involution to 0, and this expression did not detect the SYNC numerical digit at all, and promptly meaning does not have phone to link to each other with that passage.

At last, owing to increased PHASE, will detect the SYNC numerical digit, as shown in Figure 4.Then, program circuit will enter into 120 of Fig. 7 A, check 120 pairs of sync states, suppose to detect for the first time the SYNC numerical digit, and this checks false, because sync state was not equivalent to SYNC in the past.So program jump is to 122, and checking, has been 1 to determine whether the SYNC numerical digit through 4 program frames.If not, then turn back to START.In case the SYNC numerical digit has equaled 1 through 4 frames, then carry out step 124.Do not equal zero owing to SF is adjusted always, then entered for 126 steps and SF is transferred to 1(shows that the SYNC numerical digit is detected once through 4 program frames), it is a memory cell that deposits the PHASE value in that P is transferred to 0(P) and PHASE is transferred to 0.129, be that this PHASE value of 0 just is transferred to phone and turns back to START this moment.

Executive program is checked to determine whether the SYNC numerical digit occurring through 4 frames once more.Suppose in step 124 the SYNC numerical digit can occur through 4 frames, SF has been 1 this moment, therefore, redirect to 130.Check 130, to determine that P whether more than or equal to metric 128, checks promptly maximum significant digit (numerical digit 8) is to determine whether it is adjusted, to have only that having adjusted this numerical digit just represents to save as among the P phase value of at first the SYNC numerical digit being taken a sample.Suppose that this numerical digit was not transferred always, then redirect to 132, adjust the maximum significant digit of P and P adjusted to and equal the value of PHASE this moment, promptly at first to that PHASE value of SYNC spare position sampling.This shows that P has been transferred to that analog value that at first detects the SYNC numerical digit through 4 frames.134, the PHASE counter increases by 1.Check 136, to determine whether PHASE has reached 31; If do not reach, this PHASE value just is transferred to phone; If equal 31(mean reach maximum delay and this SYNC numerical digit still exists), then add by P value (deduct this maximum significant digit---128) that this PHASE value (31) is removed by 2 again and calculate the PHASE optimum value that this finishes in step 138.139, result's fractional part is removed.From theoretical and in logic, according to the P value equal 0 and last PHASE value equal 31, the optimal delay that this program can calculate is 15.Yet, in fact such result can't appear, so, 140 the SF counter is transferred to 2, and final, be shown at 142 SYNC of place.

Fix on some point, no longer detect the SYNC numerical digit when START and PHASE do not reach 31 as yet, that is to say that the increase of PHASE value has surpassed synchronous points, then will turn back to the B point of Fig. 7 B when program turns back to.In case still detect numerical digit 102 through 4 program frames, then check synchronous state 104 less than SYNC.Because state SYNC does not show, then redirect to step 114 always.At this point, SF has been transferred to 1 in the step 126 of 1(in Fig. 7 A this moment), then redirect to 144 and check the maximum significant digit of P.If it is adjusted, determined first delay value that the SYNC numerical digit is set in other words, then promptly added by P value (deducting maximum significant digit-128) that the PHASE value (PHASE-1) at last detected SYNC numerical digit place is removed by 2 again and calculate the PHASE optimum value 146.148, remove the fractional part among the result.Then, SF is transferred to 2, and is transferred to telephone set at 112 PHASE with optimum value 150.

Program turns back to initial, owing to utilized the optimum phase delay, the SYNC numerical digit will occur 100, in the 122 synchronous numerical digits that also can occur through 4 frames.Step 124 redirect to 142 and SYNC be shown.

In above specification, the present invention has been done introduction with reference to the embodiment that exemplifies especially.Yet, obviously also may carry out different modifications and changes, and can not break away from the spirit and scope of the invention that propose in the appended claims it.Therefore, this specification and accompanying drawing only are considered to have the meaning of explanation and power without limits.

Claims (30)

1, be used for and will be transferred to one first data-signal and one second device that data-signal is synchronous that is present in this second place in one second place from one first place, this device comprises:

With the device of above-mentioned first data to second place, this transmitting device comprises above-mentioned first signal delay device of an adjustable time of delay in first place;

Receive the device of above-mentioned first data-signal in second place, this device is in order to judge that whether above-mentioned first data-signal is in a selected time appearance synchronous with above-mentioned second data-signal;

Transmit the device of the coded data relevant with the respective value of above-mentioned adjustable delay time to above-mentioned first place in second place;

First place with above-mentioned time delay device in response to this coded data to change the time of delay that above-mentioned first data-signal is transferred to second place;

It is characterized in that:

Above-mentioned decision maker when second place detects above-mentioned first data-signal when occur in above-mentioned second place seclected time, the above-mentioned transmitting device in second place is to selected above-mentioned coded data of above-mentioned first place transmission, coded data that should be selected with keep value time of delay synchronous between above-mentioned first data-signal and second data-signal relevant in second place, this coded data of selecting selects the value of above-mentioned time of delay to appear at second place can make first data-signal time of delay that is implemented in above-mentioned first place in the time of selecting; Above-mentioned decision maker further comprises:

The device of above-mentioned first data-signal being sampled in the selected time;

When the part of above-mentioned first data-signal appears at above-mentioned seclected time first identification one first time of delay and when the part of above-mentioned first data-signal appears at above-mentioned seclected time for the last time the device of one second time of delay of identification; With

Between above-mentioned first and second time of delays, calculate the device of an optimum delay time.

2, the device described in claim 1 is characterized in that: described first data-signal number comprises that a digital data signal and the described device that is used to change time of delay comprise and uses the incremental change of being judged by described coded data one by one to postpone the variable word length shift register arrangement of described first data-signal.

3, the device described in claim 2 is characterized in that: described decision maker comprises digital computer unit.

4, the device described in claim 1, it is characterized in that: described coded data comprises coding digital data, and, the described device that is used for coded data is transferred to above-mentioned first place comprises the counting device that changes above-mentioned coded data with incremental mode, and each increment is corresponding to a different time of delay.

5, the device described in claim 4 is characterized in that: described transmitting device also comprises the register setting that receives above-mentioned coding digital data.

6, the device described in claim 1, it is characterized in that: described recognition device comprises the device of one second numeral that the device that produces one first numeral relevant with above-mentioned first time of delay and generation were correlated with above-mentioned second time of delay, and described calculation element comprises above-mentioned first and second numerals are asked average device.

7, the device described in claim 1 is characterized in that also being included in the constant time lag device in above-mentioned second place.

8, will be transferred to one first data-signal in one second place and the synchronous a kind of method of one second data-signal that exists in second place from one first place, the step that comprises is:

Above-mentioned first data-signal is transferred to this second place from this first place, and this transmitting step comprises above-mentioned first data-signal is postponed an adjustable time of delay;

Receive above-mentioned first data-signal in this second place and judge that in this second place whether above-mentioned first data-signal is a seclected time appearance synchronous with above-mentioned second data-signal;

Transmit the coded data relevant from this second place to above-mentioned first place with the respective value of above-mentioned adjustable delay time,

Change the above-mentioned time of delay of above-mentioned first data in above-mentioned first place in response to this coded data to second place;

It is characterized in that:

When detecting above-mentioned first data-signal when occur in above-mentioned second place seclected time, a selected above-mentioned coded data is transferred to above-mentioned first place, coded data that should be selected with keep value time of delay synchronous between above-mentioned first data-signal and second data-signal relevant in second place, this coded data of selecting selects the value of above-mentioned time of delay to appear at second place can make first data-signal time of delay that is implemented in above-mentioned first place in the time of selecting; Above-mentioned determination step further comprises:

A seclected time to above-mentioned first data signal samples;

When the part of above-mentioned first data-signal appears at above-mentioned seclected time first identification one first time of delay and when the part of above-mentioned first data-signal appears at above-mentioned seclected time for the last time one second time of delay of identification; With

Between above-mentioned first and second time of delays, calculate an optimum delay time.

9, the method described in claim 8, it is characterized in that: described identification step comprises and produces first numeral relevant with above-mentioned first time of delay and second numeral of being correlated with above-mentioned second time of delay of generation, and described calculation procedure comprises above-mentioned first and second numerals are asked average.

10, the method described in claim 9, it is characterized in that: described step to the first place transfer encoding data comprises the transfer encoding numerical data, and further comprise the step that changes above-mentioned coding digital data with incremental mode, wherein each increment is corresponding to a different time of delay.

11, the method described in claim 8 is characterized in that: described first data-signal comprises that the step of a digital data signal and wherein said change time of delay comprises the word length that changes a shift register.

12, the method described in claim 8 is characterized in that further being included in this second place and postpones the step of described first data-signal.

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