JP6475007B2 - Burst phase adjustment apparatus and method - Google Patents

Description

  The present invention relates to a burst phase adjusting apparatus and method for an ISDN line having a plurality of independent transmission / reception timings.

  FIG. 11 shows an example of a system configuration at the beginning of operation of an ISDN (Integrated Services Digital Network) network and an example of transmission / reception timings of a plurality of ISDN lines.

  The transmission / reception timing of a plurality of ISDN lines is determined by the station, and transmission and reception signals of the ISDN line A, ISDN line B, and ISDN line C are performed at the same time. For this reason, interference due to signal crosstalk occurs between the ISDN lines, but these interferences occur only between the transmission signals of the ISDN lines or between the reception signals.

  Since the difference in transmission power between transmission signals and the difference in reception power between reception signals are small, the influence of interference due to signal crosstalk is small.

  Note that transmission / reception of ISDN lines according to TTC (Information and Communication Technology Committee) standard G.961 is repeated at a cycle of 2.5 ms as shown in FIG. This transmission / reception timing is called burst timing or burst phase.

  FIG. 12 shows an example of the system configuration of a new operation method currently in the ISDN network and an example of burst timing of a plurality of ISDN lines.

  The existing new operation method is a method of using an IP (Internet Protocol) network with a low line cost instead of the ISDN network for the purpose of reducing the operation cost.

  In such a configuration, since the IP network is an asynchronous system, burst timing information synchronized with the ISDN network cannot be generated from the IP network.

  In the example of FIG. 12, the burst timing information of ISDN line A, which is an ISDN network, and the burst timing information of ISDN line B and ISDN line C generated based on the IP network are not synchronized in phase. For this reason, the reception of the ISDN line A and the transmission of the ISDN line B and the ISDN line C overlap, and interference due to signal crosstalk occurs.

  Generally, the reception power of the reception signal is smaller than the transmission power of the transmission signal due to propagation loss. Therefore, if the transmission timing of another line overlaps the reception timing, the influence of interference increases. In addition, since transmission and reception are performed at a cycle of 2.5 ms, interference due to crosstalk also occurs at a cycle of 2.5 ms.

  As described above, when independent lines whose burst timings are not synchronized with each other are adjacent to each other, interference due to signal crosstalk may occur with other lines.

  Patent Documents 1 and 2 disclose a method for reducing interference due to such crosstalk. In this method, first, the presence or absence of crosstalk and the burst timing of the crosstalk are extracted, and the burst timing of the line is set on the basis of the burst timing of the crosstalk.

Japanese Patent Laid-Open No. 04-014940 Japanese Patent Laid-Open No. 03-270441

  However, in the methods of Patent Document 1 and Patent Document 2, the power of the crosstalk (signal level) that can be detected is up to the reception sensitivity (minimum reception level) of the station or subscriber's house that detects the crosstalk. The following power crosstalk cannot be detected. Therefore, even when crosstalk cannot be detected, interference due to crosstalk may occur.

  An object of the present invention is to provide a burst capable of detecting and reducing interference caused by crosstalk of signals between ISDN lines even when the crosstalk power is low in a plurality of ISDN lines whose burst timings do not match. A phase adjustment apparatus and method are provided.

  In order to solve the above-described problem, the burst phase adjustment apparatus of the present invention includes a test pattern generation unit that generates a test pattern, a burst timing generation unit that generates a transmission timing of a transmission signal, and a communication counter according to the transmission timing. A transmission signal generating section for generating a transmission signal for setting the apparatus in a folded state, generating the transmission signal using the test pattern as a data section, and transmitting the transmission signal to the communication facing apparatus; There is a mismatch between the data part and the test pattern as a result of the comparison, a transmission / reception part that receives the received signal from the test part, a test pattern verification part that extracts the data part from the received signal and compares it with the test pattern A phase adjustment unit that determines a phase adjustment amount from the comparison result and shifts the transmission timing according to the phase adjustment amount. And wherein the Rukoto.

  Further, the burst phase adjustment method of the present invention sets the communication opposite device in a folded state, transmits a transmission signal having a test pattern as a data portion to the communication opposite device, and receives the data portion from the received signal received from the communication opposite device. Is extracted and compared with the test pattern. If there is a mismatch between the data part and the test pattern, the phase adjustment amount is determined from the comparison result, and the transmission timing of the transmission signal is shifted according to the phase adjustment amount. It is characterized by.

  According to the burst phase adjusting apparatus and method of the present invention, in a plurality of ISDN lines whose burst timings do not match, interference due to crosstalk of signals between the ISDN lines is detected and reduced even when the crosstalk power is low. It becomes possible to do.

It is a figure which shows the structural example of the burst phase adjustment apparatus of 1st embodiment of this invention. It is a figure which shows the operation example of the burst phase adjustment apparatus of 1st embodiment of this invention. It is a figure which shows the implementation example in OCU of the burst phase adjustment apparatus of 1st embodiment of this invention. It is a figure which shows the example of the operation state of OCU of 1st embodiment of this invention. It is a figure which shows the example of the transmission / reception timing of 1st embodiment of this invention. It is a figure which shows the outline | summary of the example of the phase adjustment of 1st embodiment of this invention. It is a figure which shows the structural example of the burst phase adjustment apparatus of 2nd embodiment of this invention. It is a figure which shows the implementation example in OCU of the burst phase adjustment apparatus of 2nd embodiment of this invention. It is a figure which shows the operation example of the burst phase adjustment apparatus of 2nd embodiment of this invention. It is a figure which shows the implementation example in OCU of the burst phase adjustment apparatus of 3rd embodiment of this invention. It is a figure which shows the example of the transmission / reception timing of an ISDN system. It is a figure which shows the example of the transmission / reception timing of the ISDN system containing an IP line. It is a figure which shows the frame structure and transmission / reception timing of TTC standard G.961.

[First embodiment]
The first embodiment of the present invention will be described using a specific example.

  First, FIG. 1 shows a configuration example of a burst phase adjusting apparatus according to the present embodiment. The test pattern generation unit 11, the transmission signal generation unit 12, the transmission / reception unit 13, the test pattern verification unit 14, the phase adjustment unit 15, and the burst timing generation unit 16 are configured.

  The test pattern generation unit 11 is a part that generates a test pattern.

  The burst timing generation unit 16 is a part that generates transmission timing (burst timing) of a transmission signal.

  The transmission signal generation unit 12 is a part that generates a transmission signal for setting the communication facing device in a folded state and generates a transmission signal using the test pattern generated by the test pattern generation unit 11 as a data part. Here, the return state refers to a state in which received data is transmitted as return transmission data. At this time, the transmission signal generated by the transmission signal generation unit 12 is generated according to the burst timing generated by the burst timing generation unit 16.

  The transmission / reception unit 13 is a part that transmits the transmission signal generated by the transmission signal generation unit 12 to the communication opposite device and receives a reception signal from the communication opposite device.

  The test pattern matching unit 14 is a part that extracts a data part from the received signal received by the transmission / reception unit 13 and compares the test pattern generated by the test pattern generation unit 11 with the extracted data part. Since the transmission signal generation unit 12 transmits a transmission signal for setting the communication opposite device in the folded state, the test pattern transmitted by the transmission signal is a data portion of a signal transmitted by the communication opposite device in the communication opposite device. Inserted and wrapped. Therefore, if there is no influence of interference, the test pattern generated by the test pattern generation unit 11 matches the data part of the received signal. When there is an influence of interference, a mismatch occurs between the test pattern and the data part.

  The phase adjustment unit 15 is a part that determines the phase adjustment amount from the comparison result in the test pattern matching unit 14 and adjusts the burst timing generated by the burst timing generation unit 16 according to the phase adjustment amount. The error occurrence range from when a mismatch between the test pattern and the data part occurs until the end is measured, and the phase adjustment amount is determined so that the burst timing does not cause a mismatch between the test pattern and the data part.

  By configuring the burst phase adjustment apparatus of this embodiment in this way, it is possible to detect interference by comparing the transmission signal and the reception signal returned by the communication counterpart apparatus, and adjust the burst timing so that interference does not occur. It becomes possible. Further, since the interference of the actual reception signal is detected, even when the crosstalk power is low, the interference can be detected if the interference occurs due to the influence of the crosstalk. Therefore, it is possible to detect and reduce interference caused by crosstalk of signals between ISDN lines even when the crosstalk power is low in a plurality of ISDN lines that do not match the burst timing.

  Next, an example of the operation of the burst phase adjustment apparatus of this embodiment will be described using FIG.

  First, in step S101, control for setting the communication facing device in a folded state is performed. That is, a transmission signal for setting the communication opposite device in a folded state is generated and transmitted to the communication opposite device.

  In step S <b> 102, a transmission signal using the test pattern generated by the test pattern generation unit 11 as a data portion is generated and transmitted to the communicating device via the transmission / reception unit 13.

  In step S103, the transmission / reception unit 13 extracts the data portion of the received signal received from the communication facing device, compares it with the test pattern, and detects a mismatched portion.

  In step S104, if there is no mismatch (error) as a result of the comparison in step S103, the process proceeds to step S105. If there is a mismatch, the process proceeds to step S106.

  In step S105, the folded state set in step S101 is canceled, and the phase adjustment operation ends.

  In step S106, the phase adjustment amount is determined from the comparison result in step S103, and the burst timing generated by the burst timing generation unit 16 is adjusted. Then, the process returns to step S101. By returning to step S101, the burst timing is adjusted until there is no mismatch in the result of the comparison between the received data and the test pattern in step S103.

  By operating the burst phase adjusting device of this embodiment in this way, it is possible to detect interference by comparing the transmission signal and the received signal returned by the communication counterpart device, and adjust the burst timing so that interference does not occur. It becomes possible. Further, since the interference of the actual received signal is detected, even when the crosstalk power is low, the crosstalk can be detected if the interference occurs due to the influence of the crosstalk. Therefore, it is possible to detect and reduce interference caused by crosstalk of signals between ISDN lines even when the crosstalk power is low in a plurality of ISDN lines that do not match the burst timing.

  Next, an example in which the burst phase adjusting device described above is realized by an OCU (Office Channel Unit) will be described with reference to FIG.

  FIG. 3 is a functional configuration example of the ISDN termination portion in the OCU having the function of the burst phase adjusting apparatus according to the present embodiment.

  The test pattern generation unit 11, the transmission / reception unit 13, the phase adjustment unit 15, and the burst timing generation unit 16 in FIG. 1 are respectively the test pattern generation unit 105, the transmission / reception separation transformer 101, the phase adjustment unit 114, and the burst timing generation unit in FIG. It corresponds to 117. The transmission signal generation unit 12 corresponds to the frame superimposing unit 103 and the driver 102. The test pattern verification unit 14 corresponds to the receiver 111, the received data extraction unit 110, and the test pattern verification unit 108.

  The OR 115 and the phase adjustment SW 116 generate and output information for determining the operation state of the OCU from the information input to the OR 115 and the phase adjustment SW 116. The OCU has three types of operation states: a data communication state, a test state, and a phase adjustment state.

  FIG. 4 shows the relationship between the state of the test activation signal 112, the phase adjustment SW 116, and the OR 115 and the data communication state, the test state, and the phase adjustment state, which are the three types of operation states of the OCU. Regardless of the state of the test activation signal 112, when the phase adjustment SW 116 is valid, the OCU is in the phase adjustment state, and when the phase adjustment SW 116 is invalid and the test activation signal 112 is valid, the OCU is in the test state. When both the test activation signal 112 and the phase adjustment SW 116 are invalid, the OCU enters a data communication state.

  The ISDN line 113 is connected to the transmission / reception separation transformer 101, and the transmission / reception separation transformer 101 separates the signal of the ISDN line 113 into a transmission signal and a reception signal.

  The test pattern generation unit 105 is a part that generates a test pattern.

  The transmission side switch 104 transmits to the frame superimposing unit 103 the downlink data 106 in the data communication state and the test pattern generated and output by the test pattern generation unit 105 in the test state and the phase adjustment state as transmission data. Output.

  The frame superimposing unit 103 generates a transmission frame for setting a DSU (Subscriber Line Termination Unit: Digital Service Unit), which is a communication partner, in a folded state in the test state and the phase adjustment state. Further, based on the burst timing generated by the burst timing generation unit 117, the transmission frame is superimposed on the transmission data and output to the driver 102.

  The driver 102 D / A converts the input signal and outputs it to the transmission / reception separation transformer 101 as a transmission signal.

  The received signal is A / D converted by the receiver 111, and the A / D converted signal is input to the received data extraction unit 110. The reception data extraction unit 110 identifies the data part of each reception frame of the input signal, extracts reception data, and outputs it to the reception side switch 109.

  The reception side switch 109 outputs the reception data to the uplink data 107 when in the data communication state, and outputs the reception data to the test pattern matching unit 108 during the test state and the phase adjustment state.

  The test pattern collating unit 108 collates the input received data with the test pattern, detects the occurrence of an error in the received data (mismatch between the received data and the test pattern), and outputs the detected result to the phase adjusting unit 114.

  The phase adjustment unit 114 measures the number of bits and the error occurrence position from the start to the end of error occurrence in the received data detected by the test pattern matching unit 108 in the phase adjustment state, and from the bit number and burst timing information The phase adjustment amount is determined. A method of determining the phase adjustment amount will be described later.

  The burst timing generation unit 117 shifts the burst timing by the phase adjustment amount determined by the phase adjustment unit 114 and generates and outputs a new burst timing in the phase adjustment state. Then, after completion of the phase adjustment state, the burst timing newly generated in the phase adjustment state is output even in the data communication state.

  By configuring the OCU of this embodiment in this way, it is possible to compare the OCU transmission signal and the received signal returned by the DSU to detect interference and adjust the burst timing so that interference does not occur. . Further, since the interference of the actual received signal is detected, even when the crosstalk power is low, the crosstalk can be detected if the interference occurs due to the influence of the crosstalk. Therefore, it is possible to detect and reduce interference caused by crosstalk of signals between ISDN lines even when the crosstalk power is low in a plurality of ISDN lines that do not match the burst timing.

  Next, an example of the operation when the burst phase adjusting apparatus of the present embodiment is realized by an OCU will be described.

  FIG. 5 shows the signals on two independent ISDN lines. The A line and the B line are two independent ISDN lines, and the OCU of the B line functions as the burst phase adjusting device of this embodiment.

  FIG. 5A shows a signal on the ISDN line in a state where phase adjustment has not been performed, and FIG. 5B shows a signal on the ISDN line in a state where phase adjustment has been performed in the present embodiment.

  In the state of FIG. 5A, there is a possibility that interference due to signal crosstalk may occur in the portion α where the transmission signal of the A line and the reception signal of the B line overlap. The portion of α where interference may occur occurs every 2.5 ms because the burst period of the ISDN line is constant at 2.5 ms.

  In the phase adjustment state, the frame superimposing unit 103 first generates and outputs a transmission signal for setting the DSU in a folded state. When the DSU receives a signal for returning the DSU to the folded state, the DSU turns the received signal back to the transmission signal (S101 in FIG. 2).

  Next, the OCU inserts a test pattern into the transmission signal to the ISDN line and transmits it to the DSU (S102 in FIG. 2). Then, the OCU compares the test pattern inserted in the transmission signal with the reception data included in the reception signal of the OCU that has been returned by the DSU, and detects the occurrence of an error (S103 in FIG. 2).

  If no occurrence of an error is detected, generation of a transmission signal for turning the DSU into the folded state is stopped in order to cancel the folded state of the DSU (S105 in FIG. 2). When the DSU stops receiving the signal for setting the DSU in the folded state, the DSU cancels the state in which the received signal is folded back to the transmission signal. Then, the OCU ends the phase adjustment state.

  When the occurrence of an error is detected, the OCU measures the number of bits from the start to the end of the error occurrence and determines the phase adjustment amount (S106 in FIG. 2). The OCU performs communication according to a new burst timing with the phase shifted by the determined phase adjustment amount.

  When the phase adjustment is completed, the OCU repeats the phase adjustment operation until no error is detected. Then, after the phase adjustment, communication is performed according to the burst timing adjusted in the phase adjustment state in the data communication state.

  FIG. 6 shows a case where interference due to signal crosstalk occurs in the portion α where the transmission signal of the A line and the reception signal of the B line overlap in FIG. 5A, and an error occurs in the data of the reception signal of the B line. The error detection result in the test pattern matching unit 108 is shown. The occurrence of an error in the received signal data of the B line is detected by the test pattern verification unit 108 by comparing the test pattern transmitted to the DSU with the test pattern returned from the DSU. .

  The phase adjustment unit 114 measures the number of bits from the start to the end of the error occurrence detected by the test pattern matching unit 108, identifies the range where interference occurs, and adjusts the phase adjustment amount so that interference does not occur To decide.

  The determination of the phase adjustment amount is finally performed so as to be a burst timing at which no interference occurs. For example, this can be realized by a method in which the phase adjustment amount is always fixed to a predetermined value and the phase adjustment is repeated until there is no mismatch between the test pattern and the received data.

  However, in the method in which the phase adjustment is repeated while the phase adjustment amount is always fixed and the mismatch is eliminated, it takes time to complete the phase adjustment.

  Further, it is desirable that the phase adjustment amount is determined so that the burst timing is matched with the line that receives interference as much as possible. The combined length of transmission periods of transmission signals of the A line and the B line is minimum when the burst timings of the A line and the B line are matched. The shorter the transmission period of transmission signals of the A line and the B line, the smaller the possibility of interference with other lines other than the A line and the B line. For this reason, it is desirable to determine the phase adjustment amount so as to match the burst timing as much as possible.

  For example, by determining the phase adjustment amount as follows, the transmission / reception timing of the B line can be substantially matched with the transmission / reception timing of the A layer.

  When the interference generation range is near the back of the test pattern, it can be considered that the portion near the back of the received frame is receiving interference as shown in FIG. Whether it is behind or not can be detected by, for example, a method of determining whether interference occurs in a predetermined range from the last bit of the test pattern.

  The frame of TTC standard G.961 is configured as shown in FIG. 13A, and the “20 (2B + D) slots” is the data portion. When the interference generation range is behind the test pattern, the occurrence of interference at the back portion of the data portion is detected. Since interference has occurred in the rear part of the data portion, it can be estimated that interference has occurred in the rear part of the frame. In this case, the parity bit (see “ It can be estimated that interference also occurs in the portion indicated by “P”. Therefore, the bit number “1” of the parity bit (portion indicated by “β” in FIG. 5) is added to the bit number in the range where interference has occurred (the bit number indicated by “α” in FIG. 5). Shift the phase forward by the amount added. By doing so, it is possible to shift the transmission / reception timing of the B line so that interference does not occur.

  Furthermore, assuming that interference is occurring in the DSU received signal, the transmission / reception timing of the B line can be adjusted by shifting the phase of the DSU transmission / reception phase difference (the number of bits indicated by “γ” in FIG. 5). It is possible to match the transmission / reception timing of the A line. The frame of T.G.961 is transmitted / received at the timing shown in FIG. The transmission / reception phase difference of the DSU corresponds to a portion of “6 to 7 bits” in FIG. Therefore, the number of bits obtained by adding the parity bit number 1 (β in FIG. 5) and the transmission / reception phase difference bit number 6.5 (γ in FIG. 5) to the measured bit number (α in FIG. 5). Is determined as the phase adjustment amount, the transmission / reception timings of the A layer and the B layer can be substantially matched.

  For example, if the measured test pattern error is 20 bits, the error 20 bits + the last bit of the frame 1 + the transmission / reception phase difference 6.5 bits = 27.5 bits is calculated, which corresponds to 27.5 bits. The time to perform is determined as the phase adjustment amount. The burst timing generator 117 generates and outputs a burst timing that is advanced by a time corresponding to 27.5 bits.

  In addition, CRC (Cyclic Redundancy Check) is added to the reception signal in DSU and OCU. Normally, when the OCU determines that there is an error as a result of the CRC calculation, it is determined that there is a device failure, connection error, etc., and transmission / reception with the DSU is stopped, or the person in charge of the maintenance by the failure display means To notify. In the DSU, the DSU transmits the data portion of the received signal as the data portion of the transmission signal. At this time, for the CRC portion of the transmission signal, the CRC of the received signal is not inserted as it is, but a correct CRC is added to the generated transmission signal. When interference occurs in the received signal of the OCU, it is determined that there is an error as a result of the CRC calculation, so that normal transmission / reception cannot be performed. Therefore, when a mismatch with the test pattern occurs in the received data in a state where transmission / reception is normally performed, it can be determined that interference has occurred in the DSU reception signal.

  When the interference occurrence range is closer to the test pattern, the burst timing is delayed by the phase obtained by adding the frame bit, 16 bits for the CL channel, and 39.5 bits for transmission / reception phase difference to the measured number of bits. Thus, the timing can be almost matched. However, when the interference generation range is closer to the front of the received frame, interference also occurs in the frame word of the received frame, frame synchronization may not be achieved, and normal communication may not be performed. In addition, even when interference occurs in the CRC portion, normal communication cannot be performed. For this reason, when communication with the DSU is normally established, the interference generation range is often behind the received frame.

  By operating the OCU of this embodiment as described above, it is possible to detect interference by comparing the transmission signal of the OCU and the reception signal returned by the DSU, and to adjust the burst timing so that the interference does not occur. . Further, since the interference of the actual received signal is detected, even when the crosstalk power is low, the crosstalk can be detected if the interference occurs due to the influence of the crosstalk. Therefore, it is possible to detect and reduce interference caused by crosstalk of signals between ISDN lines even when the crosstalk power is low in a plurality of ISDN lines that do not match the burst timing.

  Next, the effect of this embodiment will be described with specific numerical examples.

The amount of transmission signals on line A and line B is 6V0-P. When the amount of crosstalk between the lines is 60 dB, the amount X of the transmission signal 6V0-P of the line A and the amount of crosstalk to the line B can be calculated as follows.

Since the line loss at the maximum line length in the ISDN line is 50 dB, the minimum amount Y of the received signal on the line B can be calculated as follows.

If the burst timings of line A and line B do not match, when receiving line B, the 0.018V0-P main signal on line B will be affected by crosstalk from line A to 0.006V0-P. Become. The SN ratio at this time can be calculated as follows.

  When the burst timings of line A and line B are matched, transmission of line A and transmission of line B, and reception of line A and reception of line B are performed at the same time. In this case, the influence of the crosstalk from the line A to the line B is when the transmission of the line A crosstalks to the transmission of the line B, or when the reception of the line A crosstalks to the reception of the line B.

When transmission on line A crosstalks to transmission on line B, the amount X of transmission signal on line A crosstalks to line B X is 0.006V0-P, so the SN ratio at this time is It can be calculated as follows.

When the reception of the line A crosstalks to the reception of the line B, the amount Z of the received signal of the line A 0.018V0-P crosstalks to the line B and the SN ratio at that time can be calculated as follows.

  Thus, by matching the burst timing, the S / N ratio due to the influence of the crosstalk is greatly improved from 9.5 dB to 60 dB, and the influence of the interference due to the crosstalk can be reduced.

  As described above, in the first embodiment of the present invention, it is possible to detect the interference by comparing the transmission signal and the received signal returned by the communication counterpart device, and adjust the burst timing so that the interference does not occur. It becomes possible. Further, since the interference of the actual received signal is detected, even when the crosstalk power is low, the crosstalk can be detected if the interference occurs due to the influence of the crosstalk. Therefore, it is possible to detect and reduce interference caused by crosstalk of signals between ISDN lines even when the crosstalk power is low in a plurality of ISDN lines that do not match the burst timing.

[Second Embodiment]
Next, a second embodiment of the present invention will be described.

  FIG. 7 shows a configuration example of the burst phase adjusting apparatus 20 of the present embodiment. An attenuating unit 27 is added to the configuration example (FIG. 1) of the first embodiment. Since the test pattern generation unit 11, the transmission signal generation unit 12, the transmission / reception unit 13, the test pattern verification unit 14, the phase adjustment unit 15, and the burst timing generation unit 16 are the same as those in the first embodiment, description thereof is omitted.

  The attenuating unit 27 is a part that reduces the output level of the input transmission signal and outputs the reduced transmission signal to the transmission / reception unit 13. By reducing the output level of the transmission signal, the reception level at the communication counterpart device is also reduced. As a result, the reception signal at the communication counterpart device is likely to be affected by interference due to crosstalk. That is, by adding the attenuating unit 27 to the burst phase adjusting apparatus 10 of FIG. 1, it becomes easy to detect burst timing that may cause interference.

  FIG. 8 shows a configuration example when the burst phase adjustment apparatus of the present embodiment is realized by an OCU. An attenuator 218 and an output switch 219 are added to the configuration example (FIG. 3) of the first embodiment. Since other components are the same as those in the first embodiment, description thereof is omitted.

  The attenuating unit 218 corresponds to the attenuating unit 27 in FIG. 7 and is a part that lowers the output level of the input transmission signal.

  The output switch 219 outputs the transmission signal input from the driver 102 to the transmission / reception separation transformer 101 in the data communication state and the test state, and the transmission signal input from the attenuation unit 218 in the phase adjustment state.

  By configuring the burst phase adjustment apparatus of this embodiment in this way, as in the first embodiment, interference is detected by comparing the transmission signal with the reception signal returned by the communication counterpart device, and no interference occurs. Thus, it becomes possible to adjust the burst timing. Further, since the interference of the actual received signal is detected, even when the crosstalk power is low, the crosstalk can be detected if the interference occurs due to the influence of the crosstalk. Therefore, it is possible to detect and reduce interference caused by crosstalk of signals between ISDN lines even when the crosstalk power is low in a plurality of ISDN lines that do not match the burst timing.

  Further, in this embodiment, the reception level at the communication counterpart device is also reduced by reducing the output level of the transmission signal, and as a result, the reception signal at the communication counterpart device is likely to be affected by interference due to crosstalk. For this reason, it is possible to easily detect burst timing that may cause interference.

  Next, FIG. 9 shows an example of the operation of the burst phase adjusting apparatus 20 of the present embodiment. Step S201 is added to FIG.

  In step S201, the attenuation unit 27 is enabled to attenuate the transmission signal transmitted in the subsequent phase adjustment operation. Thereafter, step S101 and subsequent steps are the same as those in FIG.

  As described above, in the second embodiment of the present invention, similarly to the first embodiment, interference is detected by comparing the transmission signal with the received signal returned by the communication counterpart device, and no interference occurs. Thus, it becomes possible to adjust the burst timing. Further, since the interference of the actual received signal is detected, even when the crosstalk power is low, the crosstalk can be detected if the interference occurs due to the influence of the crosstalk. Therefore, it is possible to detect and reduce interference caused by crosstalk of signals between ISDN lines even when the crosstalk power is low in a plurality of ISDN lines that do not match the burst timing.

  Further, in this embodiment, the reception level at the communication counterpart device is also reduced by reducing the output level of the transmission signal, and as a result, the reception signal at the communication counterpart device is likely to be affected by interference due to crosstalk. For this reason, it is possible to easily detect burst timing that may cause interference.

[Third embodiment]
Next, a third embodiment of the present invention will be described.

  A configuration example of the burst phase adjusting apparatus of the present embodiment is the same as that in FIG. In the present embodiment, the attenuation amount in the attenuation unit 27 is variable.

  FIG. 10 shows an example of the functional configuration of the ISDN termination portion when the burst phase adjustment apparatus of this embodiment is realized by an OCU. Compared to FIG. 8, a plurality of attenuation units 318 are provided, and SW 320 is added.

  The attenuation unit 318 attenuates the output from the driver 102, and the SW 320 selects the output from the plurality of attenuation units 318.

  Decreasing the output level of the transmission signal in the OCU in the phase adjustment state also decreases the reception level at the DSU, and as a result, the reception signal at the DSU is likely to be affected by interference due to crosstalk.

  The lower the reception level at the DSU, the more likely the received signal of the DSU is affected by interference due to crosstalk, and the maximum influence of interference due to crosstalk when the received signal is at the minimum reception level that can be received by the DSU.

  The OCU can set the transmission level of the transmission signal of the OCU by the attenuation unit 318 so that the reception signal at the DSU becomes the minimum reception level that can be received by the DSU.

  Next, an example of operation in the OCU of FIG. 10 will be described. The flow of the operation is the same as that in FIG. 9, but an operation different from that of the second embodiment is performed in step S201.

  In step S201, first, the OCU performs transmission with the transmission signal transmission level set to a minimum state. At this time, since the DSU receives a reception signal having a level lower than the minimum reception level that can be received by the DSU, the DSU cannot communicate normally.

  Next, the OCU performs transmission by changing the transmission level of the transmission signal to a level higher than the minimum state. When the DSU cannot communicate normally in this state, the OCU changes the transmission level of the transmission signal to a higher level and performs transmission. Then, the transmission level of the transmission signal of the OCU is changed to a higher level until the DSU can communicate normally.

  When the DSU is in a state where communication can be performed normally, the OCU stops changing the transmission level of the transmission signal, and the transmission level is fixed to the transmission level at the time of stopping, and the process proceeds to step S101. In this way, the transmission level of the transmission signal of the OCU is set so that the reception signal at the DSU becomes the minimum reception level that can be received by the DSU.

  However, when the transmission level of the transmission signal of the OCU is set so as to be the minimum reception level that can be received by the DSU, an error due to the low reception level may occur in the DSU. As a method for avoiding this influence, for example, the following two methods are conceivable.

  In the first method, when it is possible to stop transmission / reception of an adjacent other line, transmission / reception of the other line is stopped, that is, a state in which crosstalk does not occur and an error does not occur in the above method in that state. This is a method for determining the transmission level. In a state where no crosstalk occurs, the minimum transmission level at which no error occurs in transmission / reception with the DSU is determined, and then transmission / reception of the stopped other line is started and phase adjustment is performed. By doing in this way, the error which generate | occur | produces at the time of phase adjustment can be made only into interference by crosstalk.

  The second method detects whether there is a deviation in the test pattern error location. If there is no deviation, it is determined that the reception level is low, and the transmission level of the transmission signal is further reduced. It is a way to raise. As an error deviation detection method, for example, the presence / absence of an error in a range of a predetermined number of bits, such as an 8-bit unit, is checked, and it is determined that there is an error when an error-free state continues for a predetermined number of times. Possible methods.

  As described above, in the third embodiment of the present invention, as in the first and second embodiments, interference is detected by comparing the transmission signal with the received signal returned by the communication counterpart device, and the interference It is possible to adjust the burst timing so as not to occur. Further, since the interference of the actual received signal is detected, even when the crosstalk power is low, the crosstalk can be detected if the interference occurs due to the influence of the crosstalk. Therefore, it is possible to detect and reduce interference caused by crosstalk of signals between ISDN lines even when the crosstalk power is low in a plurality of ISDN lines that do not match the burst timing.

  Furthermore, in this embodiment, the output level of the transmission signal can be set to the minimum reception level that can be received by the communication counterpart device. Therefore, it is possible to make it easier to detect burst timing that may interfere with the second embodiment.

  Each of the above-described embodiments is a preferred embodiment of the present invention, and various modifications can be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 10, 20 Burst phase adjustment apparatus 11 Test pattern generation part 12 Transmission signal generation part 13 Transmission / reception part 14 Test pattern verification part 15 Phase adjustment part 16 Burst timing generation part 27 Attenuation part

Claims (10)

A test pattern generation unit for generating a test pattern;
A burst timing generation unit for generating transmission timing of a transmission signal;
In accordance with the transmission timing, a transmission signal for generating a transmission signal for setting the communication facing device in a folded state, and generating the transmission signal using the test pattern as a data part, and
A transmission / reception unit for transmitting the transmission signal to the communication opposite device and receiving a reception signal from the communication opposite device;
A test pattern matching unit that extracts the data part from the received signal and compares it with the test pattern;
As a result of the comparison, when there is a mismatch between the data portion and the test pattern, the width of the error occurrence range from the occurrence of the mismatch between the data portion and the test pattern of the received signal to the end is measured, and the error occurrence A burst phase adjustment apparatus comprising: a phase adjustment unit that determines a phase adjustment amount based on a range width and shifts the transmission timing according to the phase adjustment amount.   The phase adjusting unit is
  When the error occurrence range is closer to the back of the test pattern, an amount based on a value obtained by adding the width of the portion of the transmission signal after the data portion and the width of the error occurrence range is the phase adjustment amount,
  The transmission timing is shifted forward according to the phase adjustment amount.
  The burst phase adjusting apparatus according to claim 1, wherein:   The phase adjusting unit is
  When the error occurrence range is closer to the back of the test pattern, the width of the portion of the transmission signal after the data portion, the width of the error occurrence range, and the position between the reception signal and the transmission signal. The amount based on the value obtained by adding the phase difference is the phase adjustment amount,
  The transmission timing is shifted forward according to the phase adjustment amount.
  The burst phase adjusting apparatus according to claim 1, wherein:   The phase adjusting unit is
  When the error occurrence range is closer to the front of the test pattern, the width of the transmission signal before the data portion, the width of the error occurrence range, and the position between the transmission signal and the reception signal The amount based on the value obtained by adding the phase difference is the phase adjustment amount,
  The transmission timing is delayed according to the phase adjustment amount.
  The burst phase adjusting apparatus according to any one of claims 1 to 3, wherein   A test pattern generation unit for generating a test pattern;
  A burst timing generation unit for generating transmission timing of a transmission signal;
  In accordance with the transmission timing, a transmission signal for generating a transmission signal for setting the communication facing device in a folded state, and generating the transmission signal using the test pattern as a data part, and
  A transmission / reception unit for transmitting the transmission signal to the communication opposite device and receiving a reception signal from the communication opposite device;
  A test pattern matching unit that extracts the data part from the received signal and compares it with the test pattern;
  As a result of the comparison, when there is a mismatch between the data part and the test pattern and there is a shift in the position where the mismatch occurs, a phase adjustment amount is determined from the comparison result, and the transmission is performed according to the phase adjustment amount. A phase adjustment unit for shifting the timing;
  An attenuator that raises the transmission level of the transmission signal when there is no deviation in the location where the mismatch occurs;
  A burst phase adjustment apparatus comprising: Set the communication facing device to the folded state,
A transmission signal having a test pattern as a data part is transmitted to the communication counterpart device;
Extracting the data part from the received signal received from the communication counterpart device and comparing it with the test pattern;
When there is a discrepancy between the data portion and the test pattern, the width of the error occurrence range from the occurrence to the end of the discrepancy between the data portion and the test pattern of the received signal is measured, and based on the width of the error occurrence range And determining a phase adjustment amount, and shifting a transmission timing of the transmission signal according to the phase adjustment amount.   When the error occurrence range is closer to the back of the test pattern, an amount based on a value obtained by adding the width of the portion of the transmission signal after the data portion and the width of the error occurrence range is the phase adjustment amount,
  The transmission timing is shifted forward according to the phase adjustment amount.
  The burst phase adjustment method according to claim 6, wherein   When the error occurrence range is closer to the back of the test pattern, the width of the portion of the transmission signal after the data portion, the width of the error occurrence range, and the position between the reception signal and the transmission signal. The amount based on the value obtained by adding the phase difference is the phase adjustment amount,
  The transmission timing is shifted forward according to the phase adjustment amount.
  The burst phase adjustment method according to claim 6, wherein   When the error occurrence range is closer to the front of the test pattern, the width of the transmission signal before the data portion, the width of the error occurrence range, and the position between the transmission signal and the reception signal The amount based on the value obtained by adding the phase difference is the phase adjustment amount,
  The transmission timing is delayed according to the phase adjustment amount.
  9. The burst phase adjustment method according to claim 6, wherein the burst phase adjustment method is performed.   Set the communication facing device to the folded state,
  A transmission signal having a test pattern as a data part is transmitted to the communication counterpart device;
  Extracting the data part from the received signal received from the communication counterpart device and comparing it with the test pattern;
  When there is a mismatch between the data part and the test pattern and there is a shift in the position where the mismatch occurs, a phase adjustment amount is determined from the comparison result, and the transmission timing of the transmission signal is determined according to the phase adjustment amount. Shift,
  Raise the transmission level of the transmission signal when there is no deviation at the location where the mismatch occurs
  A burst phase adjustment method characterized by that.

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