JP2010141759A - Reference signal generating device, and apparatus employing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reference signal generating device in which a high-precision reference signal can be easily obtained at a low cost, without lowering communication quality nor restricting call origination/termination, at a user side while utilizing a communication line employing a wide-spread ADSL system or the like, and to provide an apparatus employing the same. <P>SOLUTION: The reference signal generating device generates a reference signal while using a communication system for performing communication, via a communication line, between a station-side communication device and a user-side terminal device. The reference signal generating device includes a reference signal extraction circuit which inputs a signal containing a reference signal having a fixed frequency transmitted from the station-side communication device via the communication line and extracts the reference signal from the input signal. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention uses a signal input to a terminal device on the user side via a communication line adopting an ADSL (Asymmetric Digital Subscriber Line) method or the like, and provides a very high accuracy standard. The present invention relates to a reference signal generation device capable of generating a signal and a device using the same.

JP 2007-215104 A JP 2007-221551 A JP 2007-300471 A JP 2007-306352 A JP 2008-10994 A

  In recent years, optical communication using optical fibers has been spreading to businesses as well as ordinary homes, but as a means to realize broadband environment by enabling Internet communication etc. at low cost using existing telephone lines, The xDSL system represented by the ADSL system is widely used.

  By the way, the digital system has been used in place of the analog system in all technical fields including the communication technology adopting the ADSL system. As an example, along with the development and spread of digital communication technology, there are increasing opportunities for general users to create data consisting of character information, image information, etc., and to transmit / receive the created data.

  In the above example, there is a need to accurately record and prove the date and time when the user created the data and the date and time when the data was transmitted and received. Various time certification techniques called stamps have been proposed.

  Examples of such time certification techniques include those disclosed in JP 2007-215104 A, JP 2007-221551 A, JP 2007-300471, JP 2007-306352 A, and the like. Various proposals have already been made.

The terminal device according to the above Japanese Patent Application Laid-Open No. 2007-215104 is configured using a slave device, a terminal device capable of communicating with the slave device, and an information processing server that receives measurement values from the terminal device. A terminal device used in an information processing system,
A measurement value acquisition means for acquiring a measurement value obtained by measuring the measurement target by the slave terminal from the slave terminal;
A clock device that measures the time when the measurement value is received by the measurement value receiving means;
Time proof information generating means for generating time proof information according to the acquired time for the received measurement value;
It is comprised so that it may comprise.

Further, the recording apparatus according to the above-mentioned Japanese Patent Application Laid-Open No. 2007-221551 includes digital data acquisition means for acquiring information to be recorded as digital data,
A clock device for measuring the time when the digital data was acquired;
Current position information acquisition means for acquiring current position information when the digital data is acquired;
A secret key storage means for storing a secret key;
Signing means for generating recording data including the acquired digital data, the acquired time, and the acquired current position information, and digitally signing the generated recording data with the stored secret key;
It is comprised so that it may comprise.

Furthermore, a reference time providing device according to the above Japanese Patent Application Laid-Open No. 2007-306352 includes a reference clock device for measuring a reference time,
A signing means for electronically signing the measured reference time;
Time certificate generating means for generating a time certificate including the reference time and the electronic signature;
Time certificate providing means for providing the generated time certificate to a digital broadcasting system for transmission by digital broadcasting;
It is comprised so that it may comprise.

In addition, the data creation time certification system according to the above Japanese Patent Laid-Open No. 2007-300471 includes a terminal device provided with a data creation program, a data creation time certification server, and a time stamp server that issues a time stamp via a network. Connected data creation time certification system,
The terminal device is
Communication start means for starting communication with the data creation time certification server;
First time measuring means for measuring, as a first time, a time from when a communication start response is received from the data creation time certification server to when the data creation program is activated;
Feature data transmission means for transmitting at least feature data of content data generated by the data creation program to the data creation time certification server,
Second time measuring means for measuring the time from the end of the data creation program to the start of transmission by the feature data transmitting means as the second time;
A measurement time transmitting means for transmitting the first time and the second time to a data creation time certification server;
With
The data creation time certification server is
Third time measuring means for measuring, as a third time, a time from when the communication start request is received from the terminal device to at least receiving the feature data from the terminal device;
Feature data transfer means for transmitting feature data received from the terminal device to a time stamp server;
A time stamp receiving means for receiving a time stamp for the characteristic data transmitted by the characteristic data transferring means from the time stamp server;
A fourth time measuring means for measuring a time from when the characteristic data is transmitted to the time stamp server until the time stamp is received from the time stamp server as a fourth time;
With
The time stamp server is
Time stamp generating means for generating a time stamp including a time stamp time for the feature data received from the data creation time certification server,
A time stamp transmitting means for transmitting a time stamp to the data creation time certification server;
In the data creation time certification system with
The data creation time certification server is
A first time and a second time received from the terminal device; a third time measured by the third time measuring means; a fourth time measured by the fourth time measuring means; Data creation time proof generating means for generating a data creation time proof based on the time stamp time received from the time stamp server;
It is comprised so that it may be equipped with.

  In each of the various techniques proposed as described above, a timepiece device that measures time is an essential component. By the way, a timepiece device that measures time is used to prove time, and requires very high accuracy. As a timepiece device that requires extremely high accuracy, a reference oscillator that uses a natural frequency with extremely high stability of cesium atoms (Cs) and rubidium (Rb) atoms is currently used.

The National Institute of Information and Communications Technology uses seven cesium atomic clocks to measure time, and the cesium atomic clock has an extremely high accuracy of an error of about 10 ⁻¹² . Incidentally, the standard time in Japan is set based on this cesium atomic clock. In addition, NTT and television broadcasters and other communications carriers and broadcasters provide communications and broadcasting businesses based on accurate time without accumulated errors, using the cesium atomic clock of the National Institute of Information and Communications Technology as a reference. is doing.

  However, the above-described conventional technique has the following technical problems. That is, any of the techniques disclosed in the above-mentioned JP-A-2007-215104, JP-A-2007-300471, JP-A-2007-306352, JP-A-2007-221551, etc. It is necessary to obtain time information from a cesium atomic clock, etc. installed at the National Institute of Information and Communications Technology, etc., and a very high frequency that is the standard for accurate time etc. on the terminal equipment side used by general companies and individuals There is a technical problem that a reference signal having accuracy cannot be easily obtained.

In addition, a reference transmitter using rubidium (Rb) atoms is commercially available as the reference transmitter, and the reference transmitter using rubidium (Rb) atoms has a frequency stability of 5 × 10 ^-11 or less. However, although it has very high accuracy, it has a technical problem that the price is very high, about several million yen.

  On the other hand, as a technique for performing clock transmission without changing an existing system, a technique disclosed in Japanese Unexamined Patent Application Publication No. 2008-10994 has already been proposed.

The xDSL system according to Japanese Patent Laid-Open No. 2008-10994 is an xDSL system in which first and second xDSL (x Digital Subscriber Line) devices are arranged to face each other.
Each of the first xDSL apparatus side and the second xDSL apparatus side is configured to have modulation / demodulation means for modulating / demodulating a reference clock in a band of 4 kHz or less for telephone voice.

  However, in the case of the xDSL system according to the above-mentioned Japanese Patent Application Laid-Open No. 2008-10994, modulation / demodulation that modulates / demodulates the reference clock in the band of 4 kHz or less for telephone voice on each of the first xDSL apparatus side and the second xDSL apparatus side. It is necessary to provide new means, and the DSLAM peripheral equipment on the central office side needs to be modified for each telephone line, resulting in an increase in cost and the need to superimpose a reference clock in a band of 4 KHz or less for telephone voice. Therefore, there is a technical problem that noise may be generated in the voice, and there is a possibility that the incoming and outgoing calls may be restricted during the synchronization operation.

  Therefore, the problem to be solved by the present invention is to use a communication line adopting a widely used ADSL method or the like, without causing a reduction in communication quality, restrictions on outgoing / incoming calls, etc. on the user side, It is an object of the present invention to provide a reference signal generation device and an apparatus using the same, which can obtain a highly accurate reference signal easily and inexpensively.

In other words, in order to solve the above-described problem, the invention described in claim 1 is a communication system that performs communication via a communication line between a communication device on a station side and a terminal device on a user side. In a reference signal generation device that generates a reference signal using:
A reference signal extraction circuit is provided that inputs a signal including a reference signal having a certain frequency transmitted from the communication device on the station side via the communication line and extracts the reference signal from the input signal. Is a reference signal generating device.

According to a second aspect of the present invention, there is provided a phase correction circuit that outputs a reference signal synchronized with the reference signal on the station side by correcting the phase of the reference signal extracted by the reference signal extraction circuit. The reference signal generation device according to claim 1, further comprising:

  Furthermore, the invention described in claim 3 is characterized in that the communication line is a communication line adopting an ADSL method, and an ISDN method reference signal is used as the reference signal. Is a reference signal generation device.

  According to a fourth aspect of the present invention, the communication line is a communication line adopting an ADSL system, and a transmission / reception base signal that is phase-synchronized with an ISDN standard signal is used as the reference signal. The reference signal generation device according to claim 1, wherein:

  Furthermore, the invention described in claim 5 is characterized in that the phase correction circuit averages the phase of the reference signal extracted by the reference signal extraction circuit. This is a reference signal generating device.

The invention described in claim 6 is an apparatus using the reference signal generation device according to any one of claims 1 to 5,
A communication area for performing mobile radio communication is divided into a plurality of cells, each cell is further divided into a plurality of sectors, a radio communication base station is arranged for each cell, and the radio communication base station is supported. In a radio communication base station apparatus used in an IP data radio communication system that performs radio communication of IP data with a mobile terminal apparatus located in a cell,
Interference is achieved by synchronizing a signal used to perform wireless communication of IP data between the wireless communication base station and the mobile terminal apparatus between at least one of the plurality of cells or between the plurality of sectors. Interference reduction means for reducing
The interference reduction means generates interference by synchronizing a signal used for wireless communication of the IP data using a reference signal by the reference signal generation device according to any one of claims 1 to 5. This is a device using a reference signal generation device characterized by being reduced.

Furthermore, the invention described in claim 7 is an apparatus using the reference signal generation device according to any one of claims 1 to 5,
An apparatus using a reference signal generation device, comprising time measuring means for measuring time by counting reference signals output from the reference signal generation device.

  The invention described in claim 8 is the apparatus according to claim 7, further comprising time synchronization means for synchronizing the time measured by the time measuring means with a reference time.

  Furthermore, the invention described in claim 9 is the device according to claim 7, further comprising issuing means for issuing a time certificate based on the time measured by the time measuring means.

The invention described in claim 10 is an apparatus using the reference signal generation device according to any one of claims 1 to 5,
A plurality of reference signal generating devices arranged at locations separated from each other;
A plurality of time measuring means arranged corresponding to the plurality of reference signal generating devices, and measuring time by counting reference signals output from the respective reference signal generating devices;
An apparatus using a reference signal generating device, comprising: synchronization control means for performing synchronous control at the same time at locations separated from each other based on the time measured by each of the time measuring means.

  According to the present invention, a highly accurate reference signal can be generated on the user side using a communication line adopting a widely used ADSL method without causing a reduction in communication quality or restrictions on outgoing / incoming calls. It is possible to provide a reference signal generation device that can be obtained easily and inexpensively and a device using the same.

  Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1
1 is a block diagram showing an ADSL communication system to which a reference signal generating apparatus according to Embodiment 1 of the present invention is applied. This communication system employs the Annex C system among the ADSL systems.

  In FIG. 1, reference numeral 100 denotes a DSLAM (Digital Subscriber Line Access Multiplexer) as a station side communication device installed in a telephone station such as NTT. It is connected to a handset modem 300 as a communication terminal device installed in a user's company or an individual's home via a communication line 200 such as a telephone line. The user-side handset modem 300 can be connected to a communication network such as the Internet via a core network provided by NTT or another communication carrier, such as the communication line 200 including a general telephone line. ing.

  The DSLAM 100 is installed in a central office of a telephone station by a telecommunications carrier that provides communication by the ADSL system or the like. The DSLAM 100 is connected to a communication line 200 including a general telephone line connected to the telephone station. Thus, it branches off from a telephone exchange (not shown) through an MDF (main distributing frame) which is not shown.

  The DSLAM 100 includes a transceiver 101 for communicating with a user side handset modem 300 via a communication line 200. The transceiver 101 has a DSLAM clock signal 102 having a frequency f1 as a base signal. The ADSL method is used to transmit and receive data. In the illustrated example, only one slave modem 300 on the user side is shown, but there are of course a plurality of slave modems 300 connected to the DSLAM 100.

  By the way, the communication of the ADSL system provided by the telecommunications carrier is regulated by G.992 (G.dmt / G.Lite) etc., which is a standard standardized by the ITU (International Telecommunication Union). Annex C for Japan, Annex A for North America, Annex B for Europe, etc. are prepared as ancillary standards to which regulations in consideration of local communication conditions are added.

  In Japan, the Annex C standard is mainly used as described above, but the Annex A standard, which is a standard other than Annex C, is used by some communication carriers. Among these standards, the Annex C standard, in order to prevent ISDN interference, is also synchronized with a time-division direction control method (Time Compression Modulation) called ISDN ping-pong transmission, and also uses AMI coding by the time-division direction control method. Is used for baseband transmission. In the Annex C standard, since transmission and reception are switched in synchronization between subscriber lines, there is no near end crosstalk NEXT (Near End Crosstalk), only far end crosstalk FEXT (Far End Crosstalk), and thin subscribers. Transmission over a relatively long distance is possible with a wire.

  Here, near-end crosstalk refers to a crosstalk phenomenon that occurs on the side of a terminal that performs communication, whereas far-end crosstalk refers to electromagnetic waves, etc. in a bundle of communication lines located away from a communication terminal. This means that noise or the like is generated by the interference.

  In the time-division direction control method in ISDN, as shown in FIG. 2, communication from the station to the slave unit and communication from the slave unit to the station are switched at a time interval of 1.25 ms.

Therefore, in the DSLAM 100, as shown in FIG. 1, the timing of switching between transmission and reception using the ISDN synchronization schedule means 103 realized by hardware or software is set to a constant frequency f0 = ISDN reference signal. It is synchronized with a reference synchronization clock 104 of 400 Hz. This reference synchronous clock 104 requires very high accuracy in order to maintain communication quality. Reference signals supplied from cesium atomic clocks installed at the National Institute of Information and Communications Technology, etc. It is generated based on the reference signal outputted from the reference oscillator using the installed cesium atom or rubidium atoms in the station building, 5 × 10 ^-9 or less, very about 5 × 10 ^-12 in principle Have high frequency accuracy.

  Further, as shown in FIG. 1, a user side handset modem 300 connected to the station side DSLAM 100 via a communication line 200 includes a transceiver 301 for communicating with the station side DSLAM 100. A data signal transmitted from the DSLAM 100 on the station side as a baseband signal having a frequency f1 is received and a desired data signal is transmitted.

  As shown in FIG. 3, the ADSL signal communicated between the station-side DSLAM 100 and the user-side slave modem 300 is synchronized with the ISDN signal from the station-side DSLAM 100 to the user-side slave modem 300. And the upstream communication from the user side handset modem 300 to the station side DSLAM 100 are switched. Also, the ADSL signal transmitted and received between the station-side DSLAM 100 and the user-side handset modem 300 is divided into frames having a period of, for example, 0.264 ms, and the number of downstream frames is higher. More than the number of frames is set, and the communication line 200 is an asymmetric asymmetric digital subscriber dedicated line.

  As a result, the communication system adopting the Annex C standard ADSL system constitutes a synchronous network (ATM: Asynchronous Transfer Mode) synchronized with the ISDN signal. In this synchronous network, as shown in FIG. 4, when data is transmitted from the communication apparatus A to the communication apparatus C via the communication apparatus B, as shown in FIG. Until the data signal transmitted in synchronization with the communication device B is received by the communication device C via the communication device B, the data signal is transmitted by a reference clock that is completely synchronized between the communication devices. In this synchronous network, the frequency of the reference clock is completely the same among the communication apparatuses A to C. However, while the data signal is transmitted from the communication device A to the communication device C, a delay may occur depending on electrical characteristics such as a time constant of the communication line or the relay unit. Since the frequency of the reference clock used in each communication device is completely the same, it can be handled in a fixed manner.

  On the other hand, when the communication system is an asynchronous network typified by IP communication, data is transmitted and received between communication apparatuses A to C based on a reference clock as shown in FIG. Each of the communication devices A to C has a clock individually, and the reference clock does not need to be synchronized between the communication devices A to C. Therefore, in this asynchronous network, the frequency of the reference clock is not guaranteed, and the delay changes dynamically.

  Therefore, in this embodiment, in view of the fact that the communication system adopting the Annex C standard ADSL system constitutes a synchronous network, between the communication device on the station side and the terminal device on the user side, A reference signal generation device that generates a reference signal using a communication system that performs communication via a communication line includes a reference signal having a certain frequency transmitted from the communication device on the station side via the communication line A reference signal extraction circuit that inputs a signal and extracts a reference signal from the input signal, and a reference signal synchronized with the reference signal on the station side is corrected by correcting the phase of the reference signal extracted by the reference signal circuit. And a phase correction circuit for outputting.

  That is, in this embodiment, as shown in FIG. 1, the reference signal generating device 400 is connected to the user branching from the communication line 200 connected to the slave modem 300 on the user side. Is input with a signal including a reference signal 104 having a certain frequency f0 transmitted from the DSLAM 100 on the telephone station side via the communication line 200.

  As shown in FIG. 7, the reference signal generator 400 is roughly composed of a reference signal extraction circuit 410, a phase correction circuit 420, and a phase synchronization circuit 430. The reference signal extraction circuit 410 includes a first stage amplifier 411 that amplifies the ADSL signal 501 including the reference signal 104 transmitted from the DSLAM 100 on the telephone station side via the communication line 200. A signal 502 having a frequency corresponding to the reference signal is extracted from the signal amplified by the amplifier 411 through the first-stage filter circuit 412. Thereafter, in the reference signal extraction circuit 410, the signal 502 having a frequency corresponding to the reference signal extracted by the first-stage filter circuit 412 is further amplified by the second-stage amplifier 413 and the second-stage filter. Only a signal 503 having a frequency corresponding to the reference signal is extracted by the circuit 414. The amplifiers 411 and 413 and the filter circuits 412 and 414 may be provided in a plurality of stages (two stages in the illustrated example) as described above. However, depending on the characteristics of the amplifier and the filter circuit, only one stage is provided. Of course, it is also good.

  The reference signal 503 extracted by the reference signal extraction circuit 410 is input to the phase correction circuit 420 to correct the phase, and the phase synchronization with the station-side reference signal 104 is achieved. The phase correction circuit 420 includes a phase comparator 421, an averaging circuit 422, a VCO (voltage controlled oscillation circuit) 423, and a frequency divider 424. The reference signal 503 extracted by the reference signal extraction circuit 410 is input to the phase correction circuit 421 and compared in phase with the signal output from the frequency divider 424. The phase comparator 421 outputs a signal having a voltage corresponding to the phase difference between the input reference signal 503 and the signal output from the frequency divider 424. The signal output from the phase comparator 421 is averaged by the averaging circuit 422 and then input to the VCO 423. As the averaging circuit 422, for example, it is desirable to use a target signal to be extracted, that is, a circuit having a time constant of about ISDN synchronization frequency of 2.5 ms.

  The VCO 423 outputs a sine wave or a pulsed signal 504 having a frequency corresponding to the voltage averaged by the averaging circuit 421. The signal 504 output from the VCO 423 is input to the frequency divider 424, and the frequency divider 424 outputs a signal whose frequency is divided into N (N is an integer or a fraction).

  The phase correction circuit 420 averages the phases of the reference signal 503 and outputs a reference clock 504 that is a reference signal whose phase is synchronized with the reference signal 104 on the station side.

  Further, in this embodiment, as shown in FIG. 7, a phase synchronization circuit 430 is provided at the subsequent stage of the phase correction circuit 420, and the phase synchronization circuit 430 has a phase that is the same as the reference signal 104 on the station side. A synchronized reference clock 504 having a desired frequency is output from the output terminal 435. The phase synchronization circuit 430 includes a phase comparator 431, a loop filter circuit 432, a VCO (voltage controlled oscillation circuit) 433, and a frequency divider 434.

  The reference signal 504 synchronized with the reference signal 104 on the station side by the phase correction circuit 420 is input to the phase comparison circuit 431 and the phase of the signal output from the frequency divider 434 is compared. The phase comparator 431 outputs a signal having a voltage corresponding to the phase difference between the input reference signal 504 and the signal output from the frequency divider 434. The signal output from the phase comparator 431 is input to the VCO 433 after the phase is compensated by the loop filter circuit 432 including a low-pass filter or the like.

  The VCO 433 outputs a pulse signal having a frequency corresponding to the signal whose phase is compensated by the loop filter circuit 432. The pulse signal output from the VCO 433 is input to the frequency divider 434. The frequency divider 434 outputs a signal whose frequency is divided into N (N is an integer or a fraction). Note that the number N of frequencies divided by the frequency divider 434 can be arbitrarily set by the division number setting unit 436.

  From the phase synchronization circuit 430, the phase is synchronized with the reference signal 104 on the station side, and a reference clock 505 having a desired frequency is output from the output terminal 435 to the outside.

  In the above configuration, in the reference signal generation device according to this embodiment, the communication quality is lowered on the user side by using a communication line adopting a widely used ADSL system or the like as follows. In addition, it is possible to easily and inexpensively obtain a highly accurate reference signal without causing restrictions on outgoing and incoming calls.

  That is, in the reference signal generating apparatus 400 according to this embodiment, as shown in FIG. 1, a communication terminal is used by using a handset modem 300 which is a communication terminal apparatus possessed by a user who subscribes to ADSL provided by a communication carrier. 200 is connected to the DSLAM 100 on the station side through 200. As shown in FIG. 3, the handset modem 300 communicates with the station-side DSLAM 100 and the ISDN in order to suppress ISDN interference when communicating with the DSLAM 100.

  On the slave modem 300 side, the ADSL signal 501 transmitted from the DSLAM 100 on the station side via the communication line 200 is branched from the input side of the transceiver 301 and input to the reference signal generator 400. In the reference signal generator 400, as shown in FIG. 7, the ADSL signal 501 transmitted from the DSLAM 100 on the station side is amplified by the first stage amplifier 411, and then the ADSL signal is output by the first stage filter circuit 412. The reference signal 502 included in is extracted. Further, in the reference signal generator 400, after the extracted reference signal 502 is again amplified by the second stage amplifier 413, only the reference signal 503 included in the ADSL signal 501 is obtained by the second stage filter circuit 414. Extracted.

  Thereafter, in the reference signal generator 400, the phase of the reference signal 503 extracted by the second stage filter circuit 414 is corrected by the phase correction circuit 420, as shown in FIG. A reference signal 504 whose phase is synchronized with the signal 104 is obtained.

  Further, in the reference signal generator 400, the signal is converted into a reference signal 505 having a desired frequency by the phase synchronization circuit 430 according to the needs of the user, and then output from the output terminal 435 to an external system.

  As described above, in the reference signal generation device 400 according to the above-described embodiment, the ADSL signal 501 transmitted from the DSLAM 100 on the station side via the communication line 200 is used, and the ADSL signal included in the ADSL signal is highly accurate. Since the reference signals 502 and 503 having frequency accuracy are extracted and the phase is corrected and the reference clock 504 is output, it is not necessary to superimpose a signal to be used other than communication on the communication line 200, and the station side DSLAM periphery There is no need to add new equipment to the device, and a high-accuracy reference signal can be obtained easily and inexpensively on the user side without causing deterioration in communication quality or restrictions on outgoing / incoming calls.

Experimental Example Next, in order to confirm the operation of the reference signal generation device configured as described above, the present inventor prototyped a reference signal generation device 400 as shown in FIG. 7 and FIG. An experiment was conducted in which signals flowing through 400 locations were observed using an oscilloscope. As an oscilloscope, SS5711 manufactured by Iwasaki Tsushinki Co., Ltd. was used.

  FIG. 8 is a waveform diagram showing a state where signals flowing through various parts of the reference signal generator are observed using an oscilloscope.

  The waveform at the upper left of FIG. 8 shows the ADSL signal 501 input to the reference signal generation device 400, and this ADSL signal 501 includes a signal having a frequency band of 30 KHz to 1.1 MHz and a reference signal 104 of 400 Hz. It is.

  8 shows the output signal 502 of the first-stage filter circuit 412 of the reference signal generation device 400. This output signal 502 contains a considerable amount of noise, and is still a reference. It can be seen that only the signal is not extracted.

  8 shows the output signal 503 of the second-stage filter circuit 414 of the reference signal generation device 400. This output signal 503 is obtained by removing only noise and the like from the reference signal. As shown in FIG. 9, it can be seen that the half cycle is completely coincident with 1.25 ms, but the phase fluctuates and fluctuates.

  8 shows the output signal 504 of the phase correction circuit 420 of the reference signal generator 400, and this output signal 504 has a half cycle of 1 as shown in FIG. .25 ms is completely coincident with the reference signal 104 on the station side, and the phase is also corrected and synchronized with the reference signal 104 on the station side. Further, as described above, the output signal 504 of the phase correction circuit 420 has a ½ period that completely matches 1.25 ms, that is, the frequency completely matches the reference signal 104 on the station side, Even if it has a phase difference δ with the reference signal 104 on the side, the phase difference δ is constant and is completely synchronized.

Embodiment 2
FIG. 11 shows the second embodiment of the present invention. The same reference numerals are given to the same parts as those in the first embodiment, and in this second embodiment, the ADSL is used as the reference signal. The communication line adopting the system is configured to use a transmission / reception base signal that is phase-synchronized with the ISDN standard signal.

  In other words, in this embodiment, as shown in FIG. 11, an Annex A standard other than the Annex C standard is adopted as a communication system employing the ADSL system. Therefore, in this communication system, basically, it is assumed that the ADSL signal 501 communicated between the DSLAM 100 as the station side communication device and the user side handset modem 300 is not synchronized with the IDSN signal. It has become.

  Therefore, in this embodiment, as shown in FIG. 11, the DSLAM clock 102 itself used for data transmission by the DSLAM 100 is converted to a constant frequency f0 = 400 Hz which is an ISDN reference signal using the PLL synchronization circuit 105. It is configured to synchronize with the reference synchronization signal 104. As a result, the ADSL signal 501 itself transmitted through the communication line 200 is completely synchronized with the reference clock 104 having a constant frequency f0 = 400 Hz, which is an ISDN reference signal.

  As shown in FIG. 12, the reference signal generation apparatus 400 according to this embodiment basically includes a reference signal extraction circuit 410 itself, and the reference signal extraction circuit 410 includes a communication line 200. The DSLAM clock 102 itself synchronized with the reference signal 104 having a constant frequency f0 = 400 Hz, which is an ISDN reference signal, is extracted from the ADSL signal 501 transmitted via the ADSL signal 501 and output. At that time, the amplifier 411 and the filter circuit 412 constituting the reference signal extraction circuit 410 may be provided in a plurality of stages (for example, two stages) as necessary, as in the first embodiment.

  In addition, a phase synchronization circuit 430 is provided at the subsequent stage of the reference signal extraction circuit 410 as required so that a reference signal having a desired frequency can be output.

  In the second embodiment, the modification in the telephone office only adds the PLL synchronization circuit 104 to the DSLAM 100, and there is no problem with the sound, and a highly accurate reference signal can be obtained easily and inexpensively. Can do.

  Since other configurations and operations are the same as those of the first embodiment, description thereof is omitted.

Embodiment 3
FIG. 13 shows a third embodiment of the present invention. The same reference numerals are given to the same parts as those in the first embodiment. In the third embodiment, a reference signal generator is used. The mobile radio communication area is divided into a plurality of cells, each cell is further divided into a plurality of sectors, a radio communication base station is arranged for each cell, and the radio In a radio communication base station apparatus used for an IP data radio communication system that performs radio communication of IP data between a communication base station and a mobile terminal apparatus located in a corresponding cell, the radio communication base station and the mobile terminal Interference reduction means for reducing interference by synchronizing a signal used for wireless communication of IP data with a device at least one of the plurality of cells or between the plurality of sectors; Serial interference reduction means uses the reference signal by the reference signal generator is configured to reduce interference by synchronizing the signal used for wireless communication of the IP data.

  That is, in the third embodiment, as shown in FIG. 13, the reference signal generating apparatus according to the present invention is applied to an IP data wireless communication system. In this IP data wireless communication system, a communication area 601 is divided into a plurality of cells 602, and each cell 602 is divided into three sectors 603. At the center of each cell 602 is a wireless communication base station. 604 is installed. Each base station 604 is connected to the Internet network 607 via a relay device 606 such as a router.

  Meanwhile, a wireless communication terminal 605 including a personal computer having a communication function used by a user or a mobile phone capable of data communication performs wireless communication with the base station 604 in the cell 602 in which the wireless communication terminal 605 exists. When communicating with the wireless communication terminal 605, it is necessary to modulate or demodulate the encoded IP data. Here, in order to modulate and demodulate the encoded IP data without interfering with each other, each base station 604 needs to generate an orthogonal code or the like in synchronization with the reference synchronization signal. It is necessary to receive an accurate reference synchronization signal.

  Therefore, in this embodiment, as shown in FIG. 14, a modem 300 is installed in each base station 604 and connected to the DSLAM 100 on the station side via the communication line 200, so that each base station By using the reference signal 505 output from the reference signal generation device 400 as the reference synchronization signal used in the station 604, the reference signal 505 is input to the orthogonal code generation unit 610 and output from the orthogonal code generation unit 610. By performing modulation / demodulation by the IP data modulation / demodulation unit 613 based on the orthogonal code control signal 612, interference in IP data wireless communication can be reduced.

  Since other configurations and operations are the same as those of the first embodiment, description thereof is omitted.

Embodiment 4
FIG. 15 shows a fourth embodiment of the present invention. The same parts as those in the first embodiment will be described with the same reference numerals. In the fourth embodiment, they are arranged at locations separated from each other. A plurality of reference signal generating devices, a plurality of time measuring means arranged corresponding to the plurality of reference signal generating devices and measuring time by counting reference signals output from the respective reference signal generating devices, Synchronous control means for performing synchronous control at the same time at locations separated from each other based on the time measured by each of the time measuring means.

 That is, the reference signal generation device according to the present embodiment can be used for control applications that require highly accurate simultaneity, such as simultaneous activation of a plant in a factory, sluice gates in various places, and switching of radio waves. . In this case, for example, by measuring the precise delay of each transmission line connected to a remote location with reference to the number of synchronization signals, if this system corrects the delay accurately, the remote location can be controlled simultaneously. Is possible.

  Since other configurations and operations are the same as those of the first embodiment, description thereof is omitted.

Embodiment 5
FIG. 16 shows a fifth embodiment of the present invention. The same reference numerals are given to the same parts as those in the first embodiment. In the fifth embodiment, the reference signal generating device A time measuring means for measuring the time by counting the output reference signal;
Time synchronization means for synchronizing the time measured by the time measuring means with a reference time is provided.

  That is, in the fifth embodiment, as shown in FIG. 16, the reference signal generation device 400 of the present invention is applied to the time synchronization device 700, and the reference signal generation is performed after the reference signal generation device 400. A time measuring device 701 that measures time by counting a reference signal 505 output from the device 400 is provided. In this time measuring device 701, a synchronization device 702 having a highly accurate time standard is always or at a predetermined timing. Connected with.

  In this time synchronizer 700, the time elapsed by the time measuring device 701 is measured with high accuracy, and the delay is corrected by being synchronized with the synchronizer 702 having a high accuracy time standard at all times or at a predetermined timing. Thus, the absolute time can be obtained with high accuracy.

Thus, according to the time synchronizer 700 connected to the system using the present invention, the accuracy (10 times the accuracy of an atomic clock) compared to the accuracy (about ± 100 to 10 ms) that a normal NTP connection PC or JJY radio clock can reach. ^-12 or less) can be provided.

  Since other configurations and operations are the same as those of the first embodiment, description thereof is omitted.

Embodiment 6
FIG. 17 shows a sixth embodiment of the present invention. The same reference numerals are given to the same parts as those in the first embodiment. In the sixth embodiment, the reference signal generating device The timer is configured to measure time by counting the output reference signal, and issuance means to issue a time certificate based on the time measured by the timer.

  That is, in the sixth embodiment, the reference signal generation device 400 of the present invention is applied to the time certification device 800, and the reference signal output from the reference signal generation device 400 is provided at the subsequent stage of the reference signal generation device 400. In addition to the time counting device 801 that counts the signal 505 by counting the signal 505, the time counting device 801 includes the issuing device 802 that issues a time certificate based on the time measured by the time measuring device 801. By counting the reference signal 505 output from the reference signal generation device 400, it is possible to measure the time and prove the time with very high accuracy.

  A high-accuracy time standard is very important in the security management field where time stamps and encryption are performed. For example, “the time when text was created and encrypted”, “after that no falsification was performed. In the past, the proof of "" can only be used with an accuracy of about ± 100 to 10 ms (time stamp has an accuracy of about several ms), and if a high-speed tampering device is used, counterfeiting takes about 1 ms. It was possible.

On the other hand, in the present invention, the security level can be drastically improved by an accurate time stamp (accuracy such as ns, ps, etc.) having an accuracy similar to that of an atomic clock (10 ⁻¹² or less).

  Since other configurations and operations are the same as those of the first embodiment, description thereof is omitted.

  In the above embodiment, the case where the ADSL system is adopted as a communication system that performs communication via a communication line between the communication device on the station side and the terminal device on the user side has been described. The invention is not limited to the ADSL system, and can of course be applied to communication systems that employ other xDSL systems.

FIG. 1 is a configuration diagram showing a communication system to which a reference signal generation device according to Embodiment 1 of the present invention is applied. FIG. 2 is a timing chart showing signal switching timing in the ISDN system. FIG. 3 is a waveform diagram showing an example of the synchronous relationship between the ADSL signal and the ISDN signal. FIG. 4 is a schematic diagram showing a communication system. FIG. 5 is a chart showing a data transmission state in the synchronous network. FIG. 6 is a chart showing a data transmission state in the asynchronous network. FIG. 7 is a block diagram showing the reference signal generating apparatus according to Embodiment 1 of the present invention. FIG. 8 is a configuration diagram and waveform diagram showing an experimental example. FIG. 9 is a waveform diagram showing an ADSL signal and an ISDN signal. FIG. 10 is a waveform diagram showing an ADSL signal and an ISDN signal. FIG. 11 is a configuration diagram showing a communication system to which the reference signal generation device according to Embodiment 2 of the present invention is applied. FIG. 12 is a block diagram showing a reference signal generation apparatus according to Embodiment 2 of the present invention. FIG. 13 is a configuration diagram showing a communication system to which the reference signal generation device according to Embodiment 3 of the present invention is applied. FIG. 14 is a block diagram showing a communication base station to which the reference signal generation apparatus according to Embodiment 2 of the present invention is applied. FIG. 15 is a block diagram showing a time measuring device to which the reference signal generating device according to the fourth embodiment of the present invention is applied. FIG. 16 is a block diagram showing a time measuring device to which the reference signal generating device according to the fifth embodiment of the present invention is applied. FIG. 17 is a block diagram showing a time certification apparatus to which the reference signal generation apparatus according to Embodiment 6 of the present invention is applied.

Explanation of symbols

  100: DSLAM, 200: communication line, 300: slave modem, 400: reference signal generator, 410: reference signal extraction circuit, 420: phase correction circuit.

Claims (10)

In a reference signal generation device that generates a reference signal using a communication system that performs communication via a communication line between a communication device on the station side and a terminal device on the user side,
A reference signal extraction circuit is provided that inputs a signal including a reference signal having a certain frequency transmitted from the communication device on the station side via the communication line and extracts the reference signal from the input signal. A reference signal generator. 2. The phase correction circuit according to claim 1, further comprising a phase correction circuit that outputs a reference signal synchronized with the reference signal on the station side by correcting the phase of the reference signal extracted by the reference signal extraction circuit. The reference signal generating device described.   The reference signal generation apparatus according to claim 1, wherein the communication line is a communication line adopting an ADSL method, and an ISDN reference signal is used as the reference signal.   3. The communication line according to claim 1 or 2, wherein the communication line is a communication line adopting an ADSL system, and a transmission / reception base signal phase-synchronized with an ISDN reference signal is used as the reference signal. Reference signal generator.   5. The reference signal generation device according to claim 2, wherein the phase correction circuit averages the phase of the reference signal extracted by the reference signal extraction circuit. A device using the reference signal generation device according to any one of claims 1 to 5,
A communication area for performing mobile radio communication is divided into a plurality of cells, each cell is further divided into a plurality of sectors, a radio communication base station is arranged for each cell, and the radio communication base station is supported. In a radio communication base station apparatus used in an IP data radio communication system that performs radio communication of IP data with a mobile terminal apparatus located in a cell,
Interference is achieved by synchronizing a signal used to perform wireless communication of IP data between the wireless communication base station and the mobile terminal apparatus between at least one of the plurality of cells or between the plurality of sectors. Interference reduction means for reducing
The interference reduction means generates interference by synchronizing a signal used for wireless communication of the IP data using a reference signal by the reference signal generation device according to any one of claims 1 to 5. An apparatus using a reference signal generation device characterized by being reduced. A device using the reference signal generation device according to any one of claims 1 to 5,
An apparatus using a reference signal generation device, comprising: time measuring means for measuring time by counting reference signals output from the reference signal generation device.   8. The device according to claim 7, further comprising time synchronization means for synchronizing the time measured by the time measuring means with a reference time.   8. The device according to claim 7, further comprising issuing means for issuing a time certificate based on the time measured by the time measuring means. A device using the reference signal generation device according to any one of claims 1 to 5,
A plurality of reference signal generating devices arranged at locations separated from each other;
A plurality of time measuring means arranged corresponding to the plurality of reference signal generating devices, and measuring time by counting reference signals output from the respective reference signal generating devices;
An apparatus using a reference signal generating device, comprising: synchronization control means for performing synchronous control at the same time at locations separated from each other based on the time measured by each of the time measuring means.

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