JP5375468B2 - Transmission path measuring apparatus, measuring method, and computer program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To automatically measure a length of a balanced type transmission line without providing any signal line or the like for measurement. <P>SOLUTION: In a transmission line measuring apparatus, a loop-shaped loop-back transmission line is formed of a balanced type transmission line to be measured, a measuring current having generated a specific change in current is sent from one terminal of the loop-back transmission line, and a feedback current is received from the other terminal of the loop-back transmission line. Based on a time difference between a time at which the specific change is generated in the measuring current, and a time at which the specific change generated in the feedback current is detected, a length of the balanced type transmission line to be measured is determined. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a technique for measuring the length of a balanced transmission line.

  In a digital network, specifications regarding how a transmission signal transmitted through a balanced transmission line should appear are defined by the International Telecommunication Union (ITU-T) and the like.

  The transmission signal needs to conform to a template called a pulse mask that is defined according to the type of network at the end of a balanced transmission line or the like. The network type is, for example, a T1 network used in North America or an E1 network used in Europe.

  Therefore, the drive device has a function that enables pulse amplitude adjustment, that is, drive output adjustment, taking into account the loss due to its resistance, etc., based on the length of the balanced transmission path.

  This drive output adjustment is performed by selecting several stages of output range sections prepared in advance in the drive device. This division is determined according to the length of the balanced transmission line. For example, if the transmission path length is between 40 m (meters) and 80 m, an LBO (Line Build Out) range “2” indicating the output range section is set (see FIG. 13).

  The user who installs the balanced transmission path measures the length of the balanced transmission path, selects the LBO range, and sets it in the drive device.

  However, if the measurement of the length of the balanced transmission path is not accurate, the set LBO range may not be an appropriate LBO range. Further, although the length measurement is not wrong, there is a possibility that the set LBO range is wrong. In these cases, the transmitted signal may not conform to the prescribed pulse mask.

  Here, there is a technique for automatically measuring the transmission path length.

  For example, this is a technique for obtaining a transmission path length of an analog video signal from a time difference between an input time point and an output time point of a measurement signal (see Patent Document 1, etc.).

  If the length of the transmission line can be automatically measured, an appropriate LBO range can be set according to the measured length.

JP-A-8-307325

  However, although this technique can automatically measure the length of the transmission path, it is necessary to provide a measurement signal line separately from the analog video signal transmission path.

  It is not practical to provide a measurement signal line separately from the original transmission line only to measure the length of a balanced transmission line extending to several hundred meters.

  Accordingly, an object of the present invention is to automatically measure the length of a balanced transmission line without providing a measurement signal line or the like.

A transmission line measuring apparatus according to an aspect of the present invention is a transmission line measuring apparatus that measures the length of a balanced transmission line composed of a pair of first conductive wires and second conductive wires. Measuring current sending means for sending a measuring current causing a specific change to the first end which is one end , and sending a balanced current to the first end and the second end which is one end of the second conducting wire And a balanced current receiving means for receiving the balanced current from a third end which is the other end of the first conducting wire and a fourth end which is the other end of the second conducting wire, Receiving means for receiving a feedback current of the measurement current from a second end; a first switch for switching the connection destination of the first end to the measurement current sending means or the balanced current sending means; and the second end The second connection destination is switched to the measuring means or the balanced current sending means. A third switch for switching whether the connection destination of the switch and the third end and the fourth end is the balanced current receiving means, or the third end and the fourth end are connected to each other And the first switch is used to switch the connection destination of the first end to the measurement current sending means, the second switch is used to switch the connection destination of the second end to the measurement means, and the third switch Forming means for forming a loop-like loopback transmission line from the balanced transmission line by connecting the third end and the fourth end by a switch, and the specific change in the measured current on the basis of the specific changes that have occurred in the feedback current to the time difference between the time of detecting the time that gave rise to, before and measuring means for determining Sulfur butterfly is, the voltage value of the feedback current received by the receiving means Detect When the voltage value detection means and the detected voltage value are larger than the voltage value to be detected by the voltage value detection means when the loopback transmission line is the longest, the loopback transmission line is correctly Determining means for determining that it has been formed .

  The transmission path measuring apparatus having the above configuration can automatically measure the length of the balanced transmission path without providing a measurement signal line or the like.

It is a figure which shows the example of a functional structure of the drive side apparatus and termination | terminus apparatus of embodiment. It is a figure which shows the case where the transmission apparatus is used as a balanced transmission apparatus. It is a figure which shows the case where the transmission apparatus is used as an unbalanced transmission apparatus in order to measure the length of a balanced transmission line. It is a figure which shows the example of a functional structure of a measurement control part and an unbalanced current termination part. It is a figure which shows the example of the electric current for a measurement, and a termination resistance voltage. 6 is a time chart showing a current value of a measurement current sampled in synchronization with a reference clock and a voltage value generated in a termination resistor. It is a figure which shows the example of the bit table showing the role of F bit in a super frame format. It is a figure which shows the example of the voltage value which arises in the termination resistance of a 1310-foot loopback transmission line. It is a figure which shows the example of the voltage value which arises in the termination resistance of a 1500 foot loopback transmission line. It is a flowchart which shows the transmission line length automatic measurement process in which the transmission apparatus 1 measures the length of a balanced transmission path, and controls the drive output of a balanced current drive part. It is a flowchart which shows a drive output instruction | indication process. It is a figure which shows the example of the circuit structure for forming a balanced interface. It is a figure which shows the example of the LBO output range division corresponding to a transmission line length. It is a figure which shows the example of a functional structure of the apparatus of the modification 1. It is a figure which shows the example of a functional structure of the apparatus of the modification 2.

<Embodiment>
FIG. 12 is a diagram illustrating an example of a circuit configuration for forming a balanced interface.

  The drive side device 80 includes a balanced current drive unit 81 and a transformer 82, and the termination side device 90 includes a balanced current termination unit 91, a transformer 92, and a termination resistor 93.

  The balanced current driving unit 81 includes a pair of voltage sources having the same characteristics such as waveform, amplitude, and phase, and applies a voltage generated from each voltage source to the balanced transmission line 30 including a pair of conductors.

  Further, the termination resistor 93 provided in the termination-side device 90 differs depending on the type of network. For example, the T1 network includes a 100Ω termination resistor 93, and the E1 network includes a 120Ω termination resistor 93.

  The transformer 82 and the transformer 92 perform conversion between a balanced system and an unbalanced system.

  FIG. 1 is a diagram illustrating an example of a functional configuration of the driving device 10 and the terminal device 20 according to the embodiment. Hereinafter, the driving device 10 and the terminal device 20 are collectively referred to as “transmission device 1”.

  The transmission apparatus 1 of the embodiment normally forms a balanced interface and is used as a balanced transmission apparatus. However, when automatically measuring the length of the balanced transmission path 30, an unbalanced interface is formed and the transmission path length is measured.

<How to find the balanced transmission line length to be measured>
Here, a mechanism for automatically measuring the length of the balanced transmission line 30 will be described with reference to FIGS. Each function of the drive side device 10 and the termination side device 20 in FIGS. 1 to 3 will be described in detail in the section <Configuration>.

  FIG. 1 is a diagram illustrating an example of a functional configuration of the transmission apparatus 1 according to the embodiment.

  The drive side device 10 is obtained by adding functional units such as the measurement control unit 1000 and switches 12A to 12F to the drive side device 80 of FIG. Further, the terminal device 20 is obtained by adding functional units such as the overhead monitoring unit 5000 and the switches 22A and 22B to the terminal device 90 of FIG.

  FIG. 2 is a diagram illustrating a case where the transmission apparatus 1 is used as a balanced transmission apparatus.

  The switches 12A to 12F of the driving device 10 and the switches 22A and 22B of the terminal device 20 are set so that the transmission device 1 forms a balanced interface.

  FIG. 3 is a diagram illustrating a case where the transmission apparatus 1 is used as an unbalanced transmission apparatus in order to measure the length of the balanced transmission path.

  The transmission device 1 forms an unbalanced interface, that is, the switch 12A to the switch 12F of the driving side device 10 and the termination side device so that the loopback transmission line 31 is formed from a pair of conductors constituting the balanced transmission line 30. Twenty switches 22A and 22B are switched.

  When used as a balanced transmission device, the switches 12A to 12F, the switch 22A, and the switch 22B are switched so as to form a balanced interface through the transformer 82, the transformer 92, and the termination resistor 93. When measuring the transmission line length, the switches 12A to 12F, the switch 22A, and the switch 22B are switched so that the loopback transmission line 31 that does not pass through the transformer 82, the transformer 92, and the termination resistor 93 can be formed. It should be noted that the position of the switch 12A and the like may be arranged so that such a balanced interface and an unbalanced interface can be formed.

  2 and 3, the functional units described as solid rectangles form a balanced interface or an unbalanced interface. The transmission path through which the signal passes is indicated by a solid double line.

  In the embodiment, a current for transmission line length measurement is sent from the unbalanced current drive unit 4000 to the loopback transmission line 31, and the balanced transmission line 30 is based on the time until the current returns to the unbalanced current termination unit 2000. The length of is calculated.

  Here, with respect to how to obtain the time until the transmission path length measurement current sent from the unbalanced current drive unit 4000 (hereinafter referred to as “measurement current”) returns to the unbalanced current termination unit 2000, This will be described with reference to FIGS.

  FIG. 5 is a diagram illustrating an example of the measurement current and the termination resistance voltage.

  The drive current graph 400 shows changes in the measurement current output from the unbalanced current drive unit 4000. The measurement current is generated by changing the current so as to form the peak point 402. This current change is suitable for the transmission line cable to be measured. In the embodiment, since the balanced transmission line 30 is a T1 cable (ABAM 600 T1 Cable) used for the DS1 interface, T = 1 / 1.544 M [sec]. For example, in the case of an E1 transmission line cable, T = 1 / 2.048 M [sec].

  In addition, the termination voltage graph 200 shows a change in voltage generated in the termination resistance included in the unbalanced current termination unit 2000.

  The time axis of each of the drive current graph 400 and the termination voltage graph 200 represents the same time. That is, “0” on the time axis of the drive current graph 400 and “0” on the time axis of the termination voltage graph 200 indicate the same timing.

  The peak point 402 of the current curve 401 in the drive current graph 400 occurs at T / 2 [sec], and the peak point 202 of the voltage curve 201 in the termination voltage graph 200 occurs at T / 2 + α [sec].

  That is, it is shown that the measurement current output from the unbalanced current drive unit 4000 has reached the unbalanced current termination unit 2000 after “α” time via the loopback transmission line 31.

Therefore, the length of the balanced transmission line 30 can be obtained from the arrival time “α” according to the following Expression 1.

Formula 1) Loopback transmission line length = α x (light velocity ÷ √ (dielectric constant of transmission line cable))
Balanced transmission line length = loopback transmission line length ÷ 2
Light speed: 299,792,458 m / s
Dielectric constant: 2.3 (T1 cable)
<How to find the arrival time “α”>
The current value of the measurement current and the voltage value generated in the termination resistor are sampled in synchronization with the reference clock, and the arrival time “α” is obtained by comparing the clocks at the respective peak points. The sampled current value and voltage value are stored in a RAM (Random Access Memory), and specifically, the clock at each peak point is detected.

  A specific example is shown in FIG. FIG. 6 is a time chart showing the current value of the measurement current sampled in synchronization with the reference clock and the voltage value generated in the termination resistor.

  The “reference clock” in the first stage indicates a reference clock.

  The “measurement start” in the second stage indicates a signal indicating the start of sampling.

  The “drive current” in the third stage indicates the current value of the measurement current. In the embodiment, it is assumed that the current value indicated by “drive current” is determined in advance as a change in the measurement current, and a current according to this change is output. Note that the current value of the measurement current may be sampled.

  The “RAM address” on the fourth level indicates the address of the RAM that stores the measured voltage value. The RAM address starts from 1 and is incremented by 1 for each reference clock. Therefore, the RAM address indicates the number of elapsed clocks.

  The “termination voltage” in the fifth stage indicates a voltage value generated in the termination resistor (hereinafter, also referred to as “termination voltage value”). The termination voltage value is a value obtained by detecting a voltage value actually generated in the termination resistor 2011. Since the voltage is measured in synchronization with the reference clock, the voltage value is actually detected when it is delayed from the reference clock by the time required for measurement. When detected, it is stored in the address indicated by the RAM address. The voltage value starts to be detected when the start instruction signal 100 indicating the start of measurement is received.

  The RAM address where the largest voltage value is recorded becomes the clock value of the peak point 202 of the voltage curve 201 (see FIG. 5).

Therefore, the arrival time “α” can be obtained by the following equation 2 based on the RAM address where the largest voltage value is recorded. In Equation 2, “RAM address where the largest voltage value is recorded” is described as “RAM address”. The clock value at the peak point 402 of the current curve 401 is represented by “T ÷ 2”.

Expression 2) α [sec] = {RAM address− (reference clock frequency × T ÷ 2)}
÷ reference clock frequency

In FIG. 6, the RAM address at which the largest voltage value 103 “3.0” is recorded is “14”. The clock value in which the maximum value “60” of the current value 102 is recorded is “10”. Therefore, the time difference 104, that is, the arrival time “α” is a time corresponding to four clocks.

<Reference clock setting method>
Here, an appropriate reference clock setting method will be described.

  The reference clock is preferably generated based on a highly stable transmission source. This is because the measurement error “β” increases in proportion to the stability of the reference clock.

The error “β” is obtained by the following Equation 3.

Formula 3) β [μsec] = A ÷ (speed of light ÷ √ (dielectric constant of transmission line cable)) × B
Loopback transmission path length: A [m]
Reference clock stability: B [ppm]

For example, a high-precision oscillation source such as OCXO (Oven Controlled Xtal Oscillator) is used as a reference, and a stable clock whose frequency is converted by a PLL (Phase Locked Loop) is used as a reference clock for measurement. To do. By using a stable clock as a reference clock, measurement errors can be kept very small in measuring a long balanced transmission line length.

  Specifically, the measurement error of a balanced transmission line having a length of 200 m and a relative dielectric constant of 2.3 is as follows.

  Since the length of the balanced transmission path is 200 m, the length of the loopback transmission path is 400 m. The reference clock is 299.792458MHz (± 4.6ppm). Note that 1 ppm means that there is an error of 1 usec per second.

Measurement error β [μsec] = 400 ÷ (299792458 ÷ √2.3) × 4.6
= 6.1376E-06
When converted to distance, the error is approximately 0.00184 [m].

  Note that 4.6 parts per million of the loopback transmission line 400 m can be considered as an error in the measurement distance. This is because when there is a deviation in the reference clock to be used, a deviation also occurs in the measurement distance. Therefore, it is also possible to obtain an error of 0.00184 [m] = 400 × 4.6 ÷ 1000000.

  Hereinafter, the transmission apparatus 1 that measures the length of the balanced transmission line 30 that transmits data in the DS1 format will be described with reference to the drawings.

<Configuration>
FIG. 1 is a diagram illustrating an example of a functional configuration of the driving device 10 and the terminal device 20 according to the embodiment.

  The drive-side device 10 includes a balanced current drive unit 81, a transformer 82, a measurement control unit 1000, an unbalanced current termination unit 2000, an overhead generation unit 3000, an unbalanced current drive unit 4000, and switches 12A to 12F.

  The measurement control unit 1000 has a function of controlling other functional units in order to measure the length of the balanced transmission path 30. Details of the functions of the measurement control unit 1000 will be described later in detail with reference to FIG.

  The unbalanced current drive unit 4000 has a function of sending a measurement current, which is an unbalanced current for measuring the transmission path length, to the loopback transmission path 31.

  The unbalanced current termination unit 2000 has a function of receiving a feedback signal from the loopback transmission line 31. Details of the functions of the unbalanced current termination unit 2000 will be described later in detail with reference to FIG.

  The overhead generation unit 3000 has a function of generating overhead for notifying the termination-side device 20 that the measurement of the length of the balanced transmission path 30 is started and transmitting the overhead to the termination-side device 20 using a balanced interface. . The overhead is a frame synchronization signal and is a part for transferring frame information and maintenance monitoring information.

  Here, the frame format of the DS1 signal for transmitting overhead will be described with reference to FIG.

  There are two types of DS1 signal frame formats: a superframe format and an extended superframe format. Here, the super frame format will be described.

  One frame is composed of 193 bits and is called a multiframe with 12 frames as one unit. In the extended superframe format, one multiframe is composed of 24 frames.

  The first 1 bit of one frame is called an F bit, and maintenance monitoring such as frame synchronization and transmission error is performed using 12 bits obtained by collecting the F bits of 12 frames.

  FIG. 7 is a bit table 3010 representing the role of the F bit in the superframe format.

  A frame number 3011 indicates a frame number in the multiframe, and an F bit 3012 indicates the use of the F bit of each frame.

  The “bit number” indicates the position of the F bit in the multiframe. “Fs” indicates that it is used as a signal bit for transmitting various types of information. “Ft” indicates that it is used as a synchronization bit for frame synchronization.

  In the embodiment, for example, the termination side apparatus 20 is notified that measurement of the length of the balanced transmission line 30 is started using a signal bit indicated by “Fs”.

  Next, the termination-side device 20 includes a balanced current termination unit 91, a transformer 92, a termination resistor 93, an overhead monitoring unit 5000, an interface forming unit 6000, a switch 22A, and a switch 22B.

  The overhead monitoring unit 5000 has a function of monitoring whether overhead is transmitted from the driving device 10.

  The interface forming unit 6000 has a function of switching the switch 22A and the switch 22B to form a source using a balanced interface or an unbalanced interface.

  Next, the measurement control unit 1000 and the unbalanced current termination unit 2000 will be described with reference to FIG.

  FIG. 4 is a diagram illustrating an example of functional configurations of the measurement control unit 1000 and the unbalanced current termination unit 2000.

  The measurement control unit 1000 includes an interface formation unit 1200, an unbalanced interface formation confirmation unit 1300, a current change instruction unit 1400, an address update instruction unit 1500, a voltage conversion instruction unit 1600, a transmission path length calculation unit 1700, a drive output determination unit 1800, and a drive. An output notification unit 1900 is included.

  The unbalanced current termination unit 2000 includes a RAM 2100, a voltage value writing unit 2200, an A / D conversion unit 2300, an LPF (Low Pass Filter) 2400, a protection diode 2010, and a termination resistor 2011.

  First, the configuration of the measurement control unit 1000 will be described.

  The interface forming unit 1200 has a function of switching the switches 12A to 12F to form a source with a balanced interface or an unbalanced interface.

  The unbalanced interface formation confirmation unit 1300 has a function of confirming whether an unbalanced interface suitable for measuring the transmission path length is formed. This is because when the appropriate interface is not formed, the length of the loopback transmission line 31 cannot be measured accurately. A method for confirming whether an appropriate unbalanced interface is formed will be described in the section <Method for confirming an appropriate unbalanced interface>.

  The current change instructing unit 1400 has a function of issuing an instruction to the unbalanced current driving unit 4000 to send a measurement current (see current curve 402 in FIG. 5) that changes as determined in advance.

  The address update instruction unit 1500 has a function of instructing the voltage value writing unit 2200 of the unbalanced current termination unit 2000 to update the address in order to store the termination voltage value.

  The voltage conversion instruction unit 1600 has a function of instructing the A / D conversion unit 2300 to digitally convert the termination voltage value.

  The current change instruction unit 1400, the address update instruction unit 1500, and the voltage conversion instruction unit 1600 issue respective instructions in synchronization with the reference clock.

  The transmission path length calculation unit 1700 has a function of obtaining the length of the balanced transmission path 30 with reference to the voltage value stored in the RAM 2100. The method for obtaining the length is as described above in <How to obtain the balanced transmission line length to be measured>.

  The drive output determination unit 1800 has a function of determining the amplitude of the pulse output from the balanced current drive unit 81, that is, the drive output, and instructing the balanced current drive unit 81 according to the measured length of the balanced transmission line 30. Have.

  The drive output notification unit 1900 has a function of notifying information related to the drive output determined by the drive output determination unit 1800. Specifically, for example, information related to the drive output is displayed on a personal computer or the like connected to the drive side device 10.

  Next, the configuration of the unbalanced current termination unit 2000 will be described.

  The RAM 2100 has a function of storing a voltage value generated in the termination resistor 2011. The area of the RAM 2100 necessary for storing the voltage value will be described in the section <Required storage area amount>.

  The voltage value writing unit 2200 has a function of storing the voltage value digitally converted by the A / D conversion unit 2300 at a predetermined address in the RAM 2100. The predetermined address refers to the RAM address to be written at the time when the voltage value is detected (hereinafter referred to as “write address”). The voltage value writing unit 2200 updates the write address according to an instruction from the address update instruction unit 1500 of the measurement control unit 1000.

  The A / D conversion unit 2300 has a function of digitally converting the termination voltage value. The A / D converter 2300 receives as input a feedback current from which high-frequency noise has been removed by the LPF 2400. This is because the feedback current includes noise due to passing through the loopback transmission line 31.

  The termination resistor 2011 has a resistance value that is a half of the resistance value of the termination resistor 93 of the termination-side device 20.

<Checking the appropriate unbalanced interface>
Here, a method for confirming whether an appropriate unbalanced interface is formed will be described with reference to FIG. FIG. 8 is a diagram illustrating an example of a voltage value generated in a termination resistor of a 1310-foot loopback transmission line.

  A method for confirming whether or not an appropriate unbalanced interface is formed is that an appropriate unbalanced interface is formed when the average value of the voltage values generated in the termination resistor 2011 of the unbalanced current termination unit 2000 is larger than a threshold value. Judge.

  The threshold value is obtained as follows.

  The attenuation characteristics of the T1 cable (ABAM 600 T1 Cable) used for the DS1 interface stipulates that for every 1000 feet, the signal loss measured at 722 kHz should be less than 5 dB. Further, the longest length of the balanced transmission line 30 of the DS1 interface is 655 feet, and the longest length of the loopback transmission line 31 is 1310 feet.

Therefore, the maximum amount of attenuation that occurs when the measurement current having a frequency component of 722 kHz passes through the loopback transmission line 31 is obtained by Equation 4.

Formula 4) Maximum attenuation [dB] = Attenuation per 1000 feet [dB]
× Loopback transmission path length [feet] ÷ 1000 [feet]
6.55 [dB] = 5 [dB] x 1310 [feet] ÷ 1000 [feet]

The maximum attenuation of the longest loopback transmission line 31 is “6.55 dB”.

  That is, the voltage value generated in the termination resistor 2011 should be a value within which the attenuation from the voltage value at the drive output terminal of the unbalanced current drive unit 4000 is within “6.55 dB”.

  Therefore, when a voltage value with an attenuation of “6.55 dB” or more is confirmed, it is determined that the unbalanced interface is not correctly formed.

  In FIG. 8, “0” feet in the loopback transmission line indicate the drive output end of the unbalanced current drive unit 4000, and “1310” feet indicate the end of the loopback transmission line 31.

  The voltage value at the output terminal when the measurement current is output can be calculated from the output measurement current and the termination resistor 2011 of the unbalanced current termination unit 2000. Here, for example, “3.3 V” is set.

  The voltage value generated in the termination resistor 2011 is “1.55 V” when the attenuation amount is “6.55 dB”. This “1.55V” is the threshold value.

  Therefore, when the average value of the voltage value generated in the termination resistor 2011 is smaller than the threshold value “1.55 V”, it is determined that the unbalanced interface is not correctly formed.

  FIG. 9 is a diagram illustrating an example of a voltage value generated in the terminating resistor of the 1500 foot loopback transmission line. In this case, the threshold value is “1.39 V”.

  Even if the unbalanced interface is not formed in the termination side device 20 for some reason, and the loopback transmission line is not formed, the threshold value is effective due to the resistance provided in the termination side device 20 and the unbalanced current termination unit 2000. It becomes. Some reason is, for example, when overhead has not arrived.

<Required storage area>
Here, a method of calculating the amount of area to be secured in the RAM 2100 will be described.

  The area amount of the RAM 2100 necessary for storing the termination voltage value is obtained as follows.

First, the number of voltage values recorded in the RAM 2100 is obtained from the recording time and the number of clocks. An area necessary for storing one voltage value, for example, an amount obtained by multiplying the obtained number by one byte is the necessary area amount.

Formula 5) Recording time [sec] = Maximum value of balanced transmission line length x 2
÷ (speed of light ÷ √ (dielectric constant of transmission line cable)) + T
Number of recorded voltage values = recording time ÷ reference clock frequency

Specifically, in FIG. 6, “α + T” is the number of recorded terminal voltage values “24”. Therefore, for example, when 1 byte is required to record one termination voltage value, 24 bytes are the amount of area required for the RAM 2100.

  All or a part of the functions described above are executed by the CPUs of the drive side device 10 and the termination side device 20 executing the programs recorded in the memories of the drive side device 10 and the termination side device 20, respectively. Realized.

<Operation>
Hereinafter, the operation when the transmission apparatus 1 of the embodiment automatically measures the length of the balanced transmission path 30 and automatically controls the drive output of the balanced current drive unit 81 will be described with reference to FIGS. I will explain.

  In the transmission apparatus 1 of the embodiment, two operation modes are provided in order to control the drive output of the balanced current drive unit 81.

  The first is a “range mode” in which the drive output is determined by setting the LBO range as shown in FIG. 13 according to the length of the balanced transmission path 30.

  The second is an “optimization mode” in which drive output control is performed according to the length of the balanced transmission path 30.

  The optimization mode is a mode in which optimum drive output control is performed according to the measured transmission path length. This is a particularly effective mode when the length of the balanced transmission line is the length per boundary of the LBO range. This is because, in the LBO range, there is a range in the length of the transmission line targeted by one range, and thus the drive output by the set LBO range may not necessarily be optimal.

  Also, the standard defines the length of the transmission line that must be guaranteed to meet the appropriate pulse mask characteristics. For example, the T1 cable used in the DS1 interface is 0 m to 200 m (see FIG. 13).

  However, if the driving device used in the balanced current driving unit 81 has a high capability, even if the cable is longer than the length defined in the standard, a signal that conforms to an appropriate pulse mask characteristic at the end of the cable. Can be output.

  In the embodiment, a mode for setting the drive output is provided even if the cable is longer than the length defined in the standard, as long as it can be guaranteed to meet the pulse mask characteristics.

  An optimization mode based on the premise that the cable length is within the standard is referred to as an “intra-standard optimization mode”, and an optimization mode within the capability of the drive device is referred to as an “in-device capability optimization mode”.

  FIG. 10 is a flowchart showing a transmission path length automatic measurement process in which the transmission apparatus 1 measures the length of the balanced transmission path 30 and controls the drive output of the balanced current drive unit 81.

  First, the user attaches the balanced transmission path 30 to the transmission apparatus 1. The transmission apparatus 1 forms a balanced interface which is a normal usage pattern (see FIG. 2).

  After the mounting, the user operates a personal computer connected to the drive side device 10 to set the operation mode. Specifically, one of the three operation modes of “range mode”, “intra-standard optimization mode”, and “in-device capability optimization mode” is set.

  The drive-side device 10 that has detected the operation mode set by the user passes the detected operation mode to the measurement control unit 1000 and requests measurement of the length of the balanced transmission path 30.

  The measurement control unit 1000 acquires a threshold value (hereinafter referred to as “determination threshold value”) used for determining whether the unbalanced interface is correctly formed according to the passed operation mode.

  Specifically, when the operation mode is “optimization mode within device capability” (step S100: optimization mode within device capability), a determination threshold value for the drive capability of the drive device is obtained (step S110). For example, when the transmission path length that can guarantee the drive capability of the drive device is 1500 feet, the determination threshold is “1.39 V” (see FIG. 9).

  On the other hand, when the operation mode is “optimization mode within device capability” (step S100: range mode, intra-standard optimization mode), the longest determination threshold in the standard of the balanced transmission line 30 is obtained (step S120). For example, when the maximum length of the balanced transmission line 30 in the standard is 655 feet, the determination threshold value is “1.55 V” (see FIG. 8).

  The determination threshold value is obtained as described in the above section <Method for confirming appropriate unbalanced interface>.

  Next, the measurement control unit 1000 sets an LBO range (step S130). Specifically, the balanced current drive unit 81 is instructed to drive according to the set LBO range.

  The LBO range set here is the LBO range that is determined to be set first among the five LBO ranges shown in FIG. For example, “3”.

  In the embodiment, the LBO range is reset in order until the unbalanced interface is correctly formed to confirm that the unbalanced interface is correctly formed. The length of the loopback transmission line 31 measured in the correctly formed unbalanced interface is defined as the length of the loopback transmission line 31. Therefore, the order of the LBO ranges to be set is determined in advance.

  The measurement control unit 1000 that has set the LBO range requests the overhead generation unit 3000 to notify the termination-side device 20 of the notification that the measurement of the transmission path length is started.

  Upon receiving the request, the overhead generation unit 3000 generates a multi-frame including an overhead for starting measurement, and transmits the generated multi-frame via the balanced current driving unit 81 (see step S140, white arrow). .

  When the overhead monitoring unit 5000 of the termination-side device 20 receives the overhead for starting the measurement via the balanced current termination unit 91, the overhead monitoring unit 5000 requests the interface forming unit 6000 to form an unbalanced interface.

  Upon receiving the request, the interface forming unit 6000 operates the switch 22A and the switch 22B to form an unbalanced interface that does not pass through the transformer 92 and the termination resistor 93 (step S300, see FIG. 3).

  On the other hand, the measurement control unit 1000 that has requested the overhead generation unit 3000 to transmit overhead requests the interface formation unit 1200 to form an unbalanced interface.

  Upon receiving the request, the interface forming unit 1200 operates the switches 12A to 12F to form an unbalanced interface that does not pass through the transformer 82 (step S150, see FIG. 3).

  When an unbalanced interface is formed in both the drive side device 10 and the termination side device 20, a loopback transmission line is formed.

  The measurement control unit 1000 that has requested the interface forming unit 1200 to form an unbalanced interface waits for a sufficient time for the unbalanced interface to be formed in the terminating device 20, and then causes the current change instruction unit 1400 to start measurement. Instruct.

  Upon receiving the instruction, the current change instruction unit 1400 first instructs the unbalanced current drive unit 4000 to send the start instruction signal 100 (see FIG. 6) to the address update instruction unit 1500 and the voltage conversion instruction unit 1600. Upon receiving the instruction, the unbalanced current drive unit 4000 sends a start instruction signal 100.

  The address update instruction unit 1500 that has received the start instruction signal 100 starts an instruction to the voltage value writing unit 2200 to update the address. In addition, the voltage conversion instruction unit 1600 starts an instruction to the A / D conversion unit 2300 to digitally convert the termination voltage value.

  The current change instructing unit 1400 instructed to send the start instruction signal 100 starts to send the measurement current in accordance with a predetermined change from the clock next to the clock instructing the start instruction signal 100. The unit 4000 is instructed in synchronization with the reference clock. The time designated by the current change instruction unit 1400 is the “T” time in FIG.

  In parallel, the address update instruction unit 1500 instructs the voltage value writing unit 2200 to write, and the voltage conversion instruction unit 1600 instructs the A / D conversion unit 2300 to digitally convert the termination voltage value. . The time designated by the address update instruction unit 1500 and the voltage conversion instruction unit 1600 is the “T + α” time in FIG.

  When the instructions of the address update instructing unit 1500 and the voltage conversion instructing unit 1600 are finished, the voltage value described in the above <How to obtain the arrival time “α”> is recorded in the RAM 2100 (step S160). .

  When the termination voltage value is recorded in the RAM 2100, the measurement control unit 1000 requests the interface forming unit 1200 to form a balanced interface.

  Upon receiving the request, the interface forming unit 1200 operates the switches 12A to 12F to form a balanced interface (step S170, see FIG. 2).

  On the other hand, the overhead monitoring unit 5000 of the termination-side device 20 requests the interface forming unit 6000 to form an unbalanced interface, and then is sufficient for the drive-side device 10 to send a measurement current and record the termination voltage value. The predetermined time which is a long time is counted (step S310: No).

  When the predetermined time has elapsed (step S310: Yes), the overhead monitoring unit 5000 requests the interface forming unit 6000 to form a balanced interface.

  Upon receiving the request, the interface forming unit 6000 operates the switch 22A and the switch 22B to form a balanced interface (step S330, see FIG. 2).

  In the driving side device 10, the measurement control unit 1000 that has requested the interface forming unit 1200 to form a balanced interface confirms that the measurement current is sent and the termination voltage value is recorded in an appropriate unbalanced interface. The unbalanced interface formation confirmation unit 1300 is requested to perform

  The unbalanced interface formation confirmation unit 1300 that has received the request confirms whether or not an appropriate unbalanced interface has been formed, as described above in <Appropriate Unbalanced Interface Confirmation Method> (step S180). The unbalanced interface formation confirmation unit 1300 notifies the measurement control unit 1000 of the confirmation result.

  When the measurement control unit 1000 receives a notification from the unbalanced interface formation confirmation unit 1300 that an appropriate unbalanced interface has not been formed (step S180: No), the measurement control unit 1000 has an LBO range that has not been tried (step S180). In S190: No, the next LBO range is set (step S130), and the processes of steps S140 to S180 are performed.

  If all the LBO ranges have been tried (step S190: Yes), the measurement control unit 1000 notifies the user of an error to that effect (step S200). For example, an error message to that effect is displayed on the personal computer display.

  The measurement control unit 1000 that has notified the user of the error ends the process.

  The measurement control unit 1000 that has received notification from the unbalanced interface formation confirmation unit 1300 that an appropriate unbalanced interface has been formed (step S180: Yes), causes the transmission line length calculation unit 1700 to determine the length of the balanced transmission line 30. Request to calculate

  Upon receiving the request, the transmission path length calculation unit 1700 refers to the voltage value stored in the RAM 2100 and, as described above in <How to obtain the balanced transmission path length to be measured>, the length of the balanced transmission path 30. I ask for it. The transmission path length calculation unit 1700 passes the obtained length of the balanced transmission path 30 to the measurement control unit 1000.

  The measurement control unit 1000 that has received the length of the balanced transmission line 30 from the transmission line length calculation unit 1700 determines the drive output according to the operation mode and instructs the balanced current drive unit 81 (step S220).

  Next, with reference to FIG. 11, a process for determining the drive output according to the operation mode from the length of the balanced transmission path 30 and instructing the balanced current drive unit 81 will be described.

  FIG. 11 is a flowchart showing the drive output instruction process.

  The measurement control unit 1000 that has received the length of the balanced transmission line 30 from the transmission line length calculation unit 1700 requests the drive output determination unit 1800 to instruct the balanced current drive unit 81 to output the drive according to the operation mode. At this time, the operation mode set by the user and the length of the balanced transmission line 30 received from the transmission line length calculation unit 1700 are passed.

  Upon receiving the request, when the operation mode is “range mode” (step S400: range mode), the drive output determination unit 1800 balances the drive output in the LBO range suitable for the length of the passed balanced transmission path 30. The current driver 81 is instructed (step S410).

  Thereafter, the drive output determination unit 1800 passes the LBO range instructed to the balanced current drive unit 81 to the measurement control unit 1000. The measurement control unit 1000 to which the LBO range is passed notifies the user of the passed LBO range (step S420). For example, the transferred LBO range is displayed on the display of the personal computer as the LBO range set in the transmission apparatus 1.

  On the other hand, when the operation mode is “intra-standard optimization mode” (step S400: intra-standard optimization mode), the drive output determination unit 1800 determines whether the length of the transferred balanced transmission line 30 is within the standard. To do.

  When it is determined that the length is out of the standard (step S430: No), the drive output determination unit 1800 passes to the measurement control unit 1000 the length of the passed balanced transmission path 30 and the fact that the length is out of the standard. The measurement control unit 1000 notifies the user of such an error (step S470). For example, the length of the balanced transmission path 30 and an error message indicating that the length of the balanced transmission path 30 is out of specification are displayed on the display of the personal computer.

  When it is determined that the length is within the standard (step S430: Yes), the drive output determination unit 1800 instructs the balanced current drive unit 81 to output the drive according to the length of the passed balanced transmission path 30 ( Step S440).

  Thereafter, the drive output determination unit 1800 passes the drive output information instructed to the balanced current drive unit 81 to the measurement control unit 1000. The measurement control unit 1000 to which the instructed drive output information is passed notifies the user of the passed information (step S450). For example, the passed information is displayed on the display of the personal computer as the drive output information set in the transmission apparatus 1.

  When the operation mode is “optimization mode within device capability” (step S400: optimization mode within device capability), the drive output determination unit 1800 determines that the length of the passed balanced transmission path 30 is within the capability range of the device. To determine whether the length is.

  When it is determined that the length exceeds the capability range (step S460: No), the drive output determination unit 1800 performs measurement control to determine that the measured length of the balanced transmission path 30 and the balanced transmission path 30 are too long. Part 1000. The measurement control unit 1000 notifies the user of such an error (step S470). For example, the length of the balanced transmission path 30 and an error message indicating that the balanced transmission path 30 is too long are displayed on the display of the personal computer.

  When it is determined that the length is within the capacity range (step S430: Yes), the drive output determination unit 1800 displays the drive output corresponding to the length of the passed balanced transmission line 30 as the balanced current drive unit. 81 is instructed (step S440).

  Thereafter, the drive output determination unit 1800 passes the drive output information instructed to the balanced current drive unit 81 to the measurement control unit 1000. The measurement control unit 1000 to which the instructed drive output information is passed notifies the user of the passed information (step S450). For example, the passed information is displayed on the display of the personal computer as the drive output information set in the transmission apparatus 1.

<Other embodiments>
As mentioned above, although embodiment of this invention was described, this invention may be as follows not only the said form.
(1) In the embodiment, three operation modes have been described. However, only one of the operation modes may be performed. In addition, when the operation mode is “range mode”, an appropriate LBO range corresponding to the transmission path length is automatically set. First, the user sets the LBO range, and the set LBO range is appropriate. It is good also as judging whether there exists.
(2) In the embodiment, the length of the balanced transmission path 30 is measured in a state where the balanced transmission path 30 is attached to the drive side apparatus 10 and the termination side apparatus 20. However, the loop-back transmission line 31 may be formed by mounting the terminal-side apparatus 50 that only connects the ends of the two conductors constituting the balanced transmission line 30 instead of the terminal-side apparatus 20 (Modification 1). ). For example, as shown in FIG. 14, the termination-side device 50 has a connector 51 for mounting the balanced transmission path 30 and connects the terminations of two conductors of the mounted balanced transmission path 30. In this state, the length of the balanced transmission line 30 can be measured by sending a measurement current from the driving device 10 as in the embodiment.

  By doing so, it is possible to know the length of the balanced transmission path 30 without attaching the balanced transmission path 30 to the terminal device 20.

  Further, as shown in FIG. 15, the drive-side device 60 may be mounted instead of the drive-side device 10 to form the loopback transmission line 31 (Modification 2). The drive side device 60 includes a connector 61 for mounting the measurement control unit 1000, the unbalanced current drive unit 4000, the unbalanced current termination unit 2000, and the balanced transmission line 30.

In this way, the length of the balanced transmission line 30 can be easily measured.
(3) In the embodiment, the measurement current is generated by changing the current so as to generate a specific change called a peak, but may be another specific change. For example, the change in current per reference clock becomes large.
(4) The drive-side device 10 or the like may be realized by all or part of the components shown in FIG.
(5) The drive-side device 10 or the like may be realized by all or part of the components shown in FIG. 1 or the like by a computer program, or may be implemented in any other form.

  In the case of a computer program, a program written in any recording medium such as a memory card or CD-ROM may be read and executed by a computer, or a program may be downloaded and executed via a network. Also good.

10 60 80 Drive side device 12 22 Switch 20 50 90 Termination side device 30 Balanced transmission path 31 Loopback transmission line 51 61 Connector 81 Balanced current drive unit 82 92 Transformer 91 Balanced current termination unit 93 2011 Termination resistance 200 Termination voltage graph 400 Drive Current graph 1000 Measurement control unit 1200 Interface formation unit 1300 Unbalanced interface formation confirmation unit 1400 Current change instruction unit 1500 Address update instruction unit 1600 Voltage conversion instruction unit 1700 Transmission path length calculation unit 1800 Drive output determination unit 1900 Drive output determination unit 2000 Balanced current termination unit 2010 Protection diode 2200 Voltage value writing unit 2300 A / D conversion unit 3000 Overhead generation unit 3010 F bit table 4000 Unbalanced current drive unit 5000 Overhead monitoring unit 6000 Interface formation section

Claims (5)

A transmission path measuring device for measuring the length of a balanced transmission path composed of a pair of first conductors and second conductors,
And measuring the current sending means for sending the measured current that caused a particular change in the first end which is one end of said first conductor,
Balanced current sending means for sending a balanced current to the first end and a second end which is one end of the second conductor;
Balanced current receiving means for receiving the balanced current from a third end which is the other end of the first conductor and a fourth end which is the other end of the second conductor;
Receiving means for receiving a feedback current of the measurement current from the second end;
A first switch for switching the connection destination of the first end to the measurement current sending means or the balanced current sending means;
A second switch for switching the connection destination of the second end to the measuring means or the balanced current sending means;
A third switch for switching whether to connect the third end and the fourth end to the balanced current receiving means, or to connect the third end and the fourth end;
The connection destination of the first end is switched to the measurement current sending means by the first switch, the connection destination of the second end is switched to the measurement means by the second switch, and the third switch is used by the third switch. Forming means for forming a loop-like loopback transmission line from the balanced transmission line by connecting the third end and the fourth end;
Based on the time difference between the time of detecting the specific changes that have occurred in the feedback current and when causing the specific changes in the measured current, a measuring means for determining the pre-Sulfur butterfly is,
Voltage value detecting means for detecting the voltage value of the feedback current received by the receiving means;
When the detected voltage value is larger than the voltage value to be detected by the voltage value detection means when the loopback transmission line is the longest, it is determined that the loopback transmission line is correctly formed. Judgment means,
A transmission path measuring device comprising: Before Kihaka constant current varies so as to gradually become smaller after the value of the current is gradually increased, a current that is when the value of the current is maximum, the specific to the measured current When the change is caused, it means the time when the current having the maximum value is sent,
The transmission line measuring apparatus according to claim 1 . Balanced signal sending means for generating parallel signals and sending them to the balanced transmission line;
The measurement according to the Sulfur butterfly of prior determined in section, the transmission path measuring apparatus according an output control means for controlling the output, to claim 1 or claim 2 comprising a balanced signal sending means. A transmission path measuring method for measuring the transmission path measuring device the length of the balanced transmission line consisting of a pair of first conductor and the second conductor,
In the transmission line measuring device,
A measurement current sending means for sending a measurement current causing a specific change to the first end which is one end of the first conducting wire is provided,
Equilibrium current sending means for sending the balanced current to the first end and the second end which is one end of the second conducting wire is provided,
There is provided a balanced current receiving means for receiving the balanced current from a third end that is the other end of the first conducting wire and a fourth end that is the other end of the second conducting wire,
A receiving means for receiving the feedback current of the measurement current from the second end;
A first switch for switching the connection destination of the first end to the measurement current sending means or the balanced current sending means;
A second switch for switching the connection destination of the second end to the measuring means or the balanced current sending means;
A third switch is provided for switching whether the connection destination of the third end and the fourth end is the balanced current receiving means or the third end and the fourth end are connected to each other. Every
In measuring the length,
The connection destination of the first end is switched to the measurement current sending means by the first switch, the connection destination of the second end is switched to the measurement means by the second switch, and the third switch is used by the third switch. By connecting the third end and the fourth end , a loop-shaped loopback transmission line is formed from the balanced transmission line,
The measured current is delivered by the measuring current supplying means,
Receiving the feedback current by the receiving unit,
Detecting the voltage value of the feedback current received by the receiving means;
When the detected voltage value is larger than the voltage value to be detected when the loopback transmission line is the longest, it is determined that the loopback transmission line is correctly formed;
Based on the time difference between the time of detecting the specific changes that have occurred in the feedback current and when causing the specific changes in the measured current, Ru seek pre Sulfur butterfly is,
Measuring method. A measurement current that sends out a measurement current that causes a specific change in the length of a balanced transmission line composed of a pair of first and second conductors at the first end that is one end of the first conductor. Sending means, balanced current sending means for sending a balanced current to the first end and a second end that is one end of the second conducting wire, a third end that is the other end of the first conducting wire, and Balanced current receiving means for receiving the balanced current from a fourth end which is the other end of the second conducting wire, receiving means for receiving a feedback current of the measurement current from the second end, and the first A first switch for switching an end connection destination to the measurement current sending means or the balanced current sending means; a second switch for switching a connection end of the second end to the measurement means or the balanced current sending means; 3 and the fourth end connected to the balanced current Or the stage, or, a third end and the computer program for measuring the fourth device having a third switch for switching whether to connect the ends to each other,
In the device,
The connection destination of the first end is switched to the measurement current sending means by the first switch, the connection destination of the second end is switched to the measurement means by the second switch, and the third switch is used by the third switch. By connecting the third end and the fourth end, a forming process for forming a loop-shaped loopback transmission line is executed from the balanced transmission line,
A measurement current sending process for sending the measurement current by the measurement current sending means ;
A receiving process for receiving the feedback current by the receiving means ;
Causing the receiving means to detect a voltage value of the feedback current received;
When the detected voltage value is larger than the voltage value to be detected when the loopback transmission line is the longest, a determination process is performed to determine that the loopback transmission line is correctly formed,
Based on the time difference between the time of detecting the specific changes that have occurred in the feedback current and when causing the specific changes in the measured current, to perform the measuring process for determining the pre-Sulfur butterfly is,
Computer program.

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