JP2005311411A - Line state detecting apparatus, and transmitter and receiver in balanced transmission system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a line state detecting apparatus capable of detecting a balanced state of a transmission line and to provide a transmitter and a receiver for a balanced transmission system capable of controlling the balanced state in response to a detection result so as to enhance the balance. <P>SOLUTION: The line state detecting apparatus provided to a balanced transmission system includes: impedances Z11, Z12 respectively inserted in series with the transmission line comprising a pair of conductors W1, W2 connected to a transmission section 13; first and second detection sections 11, 12 for respectively detecting a voltage across the impedances Z11, Z12; and a differential circuit 14 for detecting a difference between outputs of the first and second detection sections 11, 12. An output of the differential circuit 14 provides a difference of currents respectively flowing through the conductors W1, W2 of the transmission line so as to detect an unbalanced component between the conductors W1, W2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a line state detection device that detects a state of a transmission line in a balanced transmission system that performs data transmission using a pair of conductors, and a transmission device and a reception device of a balanced transmission system including the same.

  Conventionally, balanced transmission systems that perform data transmission using a pair of transmission lines in a balanced state have been widely used. In this type of balanced transmission system, a transmission line such as a dedicated communication line is often used, such as a telephone line, and a certain degree of balance is usually maintained.

  An example of the transmission part and transmission line of the conventional balanced transmission apparatus is shown in FIG. This balanced transmission device is configured to send a signal from a transmission unit 92 to a transmission line including a pair of conductors W1 and W2 via a transmission transformer T91. At this time, the current of the transmission signal transmitted from the transmission unit 92 depends on the characteristics of the transmission unit 92 and the transmission lines W1 and W2.

  The transmission line from the transmission unit to the reception unit is originally required to be perfectly balanced, but in reality, it is connected to the unbalanced elements in the transmission unit and the reception unit, the wiring conditions of the transmission line, and the middle. In reality, the current flowing through the conductors W1 and W2 of the transmission line is not completely balanced. When the current flowing through the transmission line is unbalanced in this way, a part of the transmission power leaks from the transmission line to the outside, so that the data transmission characteristics deteriorate and problems such as interference occur.

  Recently, a balanced transmission system has been proposed in which data transmission is performed by superimposing a high-frequency signal on a power line carrying power such as a commercial power source. In particular, since such a power line is not originally a communication line, the degree of balance may vary depending on the wiring situation in each house, equipment connected to the power source, and the like. For this reason, when a power line is used as a transmission line, the degree of balance may vary depending on each environment, and transmission characteristics may vary greatly.

  Therefore, in a balanced transmission system, it is preferable to improve the balance of the transmission line by detecting the state of the transmission line and controlling the current or voltage in the two lines. Detection and control were not done.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a line state detection device capable of detecting a balanced state of a transmission line in a balanced transmission system.

  Another object of the present invention is to provide a transmission device and a reception device for a balanced transmission system that can control the balanced state of the transmission line based on the detection result in the balanced transmission system and can improve the balance. To do.

A line state detection device according to the present invention is a line state detection device that detects a state of a transmission line in a balanced transmission system that performs data transmission using a pair of conductors, the current flowing through the conductor or the voltage of the conductor or the And an individual detection means for detecting both for each conductor, and an unbalanced component calculation means for obtaining a current difference for each conductor detected by the individual detection means, a voltage difference for each conductor, or both. Is.
This makes it possible to detect an unbalanced state such as a current or voltage unbalanced component in the transmission line. For example, the degree of balance can be improved by controlling the balanced state of the transmission line based on the detection result.

Moreover, it is said line | wire state detection apparatus as 1 aspect of this invention, Comprising: The said pair of conductor shall be a power line.
Thereby, in a balanced transmission system using a power line as a transmission line, it is possible to detect an unbalanced state such as an unbalanced component of a current or voltage in the transmission line.

In addition, as an aspect of the present invention, in the above-described line state detection device, the individual detection unit includes a current detection unit that detects a current flowing through the conductor for each conductor.
Thereby, it is possible to detect the unbalanced state in the transmission line by detecting the current flowing through the pair of conductors for each conductor and calculating the difference between them.

Further, as one aspect of the present invention, in the line state detection device, the current detection unit includes an impedance inserted in series with each of the pair of conductors, and a voltage for detecting a voltage at both ends of the impedance. It shall include a detection part.
This detects the current in each conductor using the impedance inserted in series with each of the pair of conductors, and calculates the difference between them to detect an unbalanced state in the transmission line with a simple configuration. Is possible.

Also, as one aspect of the present invention, in the line state detection device described above, the current detection unit includes a current transformer in which a primary winding is inserted in series in each of the pair of conductors, and two current transformers. And a current detector for detecting the next winding current or voltage.
Thus, by using a current transformer inserted in series with each of a pair of conductors, the current in each conductor is detected in a state separated from the transmission line, and the difference between these is calculated, thereby allowing transmission line transmission with a simple configuration. It is possible to detect an unbalanced state in the transmission line in a state where the detector and the detection unit are separated.

In addition, as an aspect of the present invention, in the line state detection device described above, the individual detection unit includes a voltage detection unit that detects a voltage with respect to a predetermined reference potential in the conductor for each conductor.
Thereby, it is possible to detect an unbalanced state in the transmission line by detecting the voltage in the pair of conductors for each conductor and calculating the difference between them.

Further, as one aspect of the present invention, in the line state detection device described above, the unbalanced component calculation unit may calculate the difference between the current for the forward path and the return path for each conductor, and the in-phase voltage for each conductor. And at least one of the minutes.
This makes it possible to detect the difference in current or voltage detected for each conductor based on the difference in current between the forward path and the return path for each conductor, the in-phase component of the voltage for each conductor, and detect unbalanced components in the transmission line. It becomes.

Further, as one aspect of the present invention, in the above-described line state detection device, the unbalanced component calculating unit calculates the magnitude and direction of the unbalanced component between the pair of conductors based on the difference. To do.
This makes it possible to detect the direction along with the magnitude of the unbalanced component in the transmission line.

Further, as one aspect of the present invention, in the above-described line state detection device, the unbalanced component calculation unit includes a transmission signal output to the conductor, a current or voltage in the conductor, a forward path and a return path in the conductor. Phase comparison with current difference or common-mode voltage is performed.
As a result, it is possible to detect the direction of the unbalanced component in the transmission line by comparing the phase of the transmission signal sent to the conductor or the current or voltage in this conductor with the current difference between the forward path and the return path in the conductor or the in-phase voltage component. Become.

Further, as one aspect of the present invention, in the above-described line state detection device, the unbalanced component calculation unit includes a transmission signal output to the conductor, a current or voltage in the conductor, a forward path and a return path in the conductor. The product of the current difference or the common mode voltage shall be calculated.
As a result, the direction and magnitude of the unbalanced component in the transmission line can be detected by the product of the transmission signal sent to the conductor or the current or voltage in this conductor and the current difference or common-mode voltage component in the forward and return paths in the conductor. It becomes possible.

Further, as one aspect of the present invention, in the above-described line state detection device, a transmission signal output to the conductor or a current or voltage in the conductor and a current difference between the forward path and the return path in the conductor or an in-phase voltage component Phase shift means for adjusting at least one of the phases is provided.
Thus, by adjusting the phase shift by the phase shift means and performing the phase comparison or product calculation, the direction and magnitude of the unbalanced component in the transmission line can be accurately detected.

The transmission device of the present invention is a transmission device used in a balanced transmission system that performs data transmission using a pair of conductors, and includes a transmission-side line state detection device including any one of the above-described line state detection devices.
Thereby, in the transmission device, it becomes possible to detect an unbalanced state such as an unbalanced component of current or voltage in the transmission line. For example, the degree of balance can be improved by controlling the balanced state of the transmission line based on the detection result.

Further, as one aspect of the present invention, the transmission device includes a transmission signal control unit that controls a transmission signal output to the conductor based on an output of the transmission-side line state detection device.
As a result, by controlling the transmission signal output to the conductor based on the detection result of the unbalanced state in the transmission line detected by the line state detection device, the unbalanced component of the transmission line can be reduced, and the degree of balance can be reduced. It becomes possible to improve.

A receiving apparatus according to the present invention is a receiving apparatus used in a balanced transmission system that performs data transmission using a pair of conductors, the receiving-side line state detecting apparatus including any one of the above-described line state detecting apparatuses, and the receiving-side line. And a line state output unit that outputs a state detection signal indicating the line state of the transmission line based on the output of the state detection device.
As a result, the receiving device can detect an unbalanced state such as an unbalanced component of the current or voltage in the transmission line. For example, the degree of balance can be improved by transmitting the detection result to the transmission side and controlling the balanced state of the transmission line.

The transmission device of the present invention is a transmission device used in a balanced transmission system that performs data transmission using a pair of conductors, and is a transmission that outputs to the conductor based on the state detection signal output from the reception device. A transmission signal control unit for controlling the signal is provided.
Thus, by controlling the transmission signal output to the conductor based on the state detection signal detected by the receiving device, it is possible to reduce the unbalanced component of the transmission line and improve the balance.

A balanced transmission system according to the present invention is a balanced transmission system that performs data transmission using a pair of conductors, and includes a transmission-side line state detection device including any one of the above-described line state detection devices, and transmission output to the conductors. A transmission device including a transmission signal control unit for controlling a signal, a reception-side line state detection device including any one of the above-described line state detection devices, and a line of the transmission line based on an output of the reception-side line state detection device And a line state output unit that outputs a state detection signal indicating a state, and the transmission signal control unit is configured to output the state of the transmission side line state detection device and the state detection output from the reception device. The transmission signal output to the conductor is controlled based on the signal.
As a result, by controlling the transmission signal output to the conductor based on the detection result of the unbalanced state in the transmission line detected by the line state detection device, the unbalanced component of the transmission line can be reduced, and the degree of balance can be reduced. It becomes possible to improve.

  ADVANTAGE OF THE INVENTION According to this invention, the line state detection apparatus which can detect the balanced state of a transmission line can be provided in a balanced transmission system. Further, in the balanced transmission system, it is possible to provide a transmission device and a receiving device of the balanced transmission system that can control the balanced state of the transmission line based on the detection result and can improve the degree of balance.

  In an embodiment of the present invention, a line state detection device that detects a state of a transmission line in a balanced transmission system that performs data transmission through a balanced transmission line, and a transmitter and a receiver of a balanced transmission device that includes this line state detection device, In addition, a configuration example of a balanced transmission system having both the transmitter and the receiver is shown. The line state detection apparatus of this embodiment is applicable to a balanced transmission system such as a power line communication system using a power line as a transmission line. Moreover, as data communication, it is used suitably for data communication, such as power line communication which uses a frequency division multiplexing signal, OFDM (Orthogonal Frequency Division Multiplexing), or ADSL (Asymmetric Digital Subscriber Line).

  First, the outline | summary of the transmitter and receiver of the balanced transmission apparatus which concerns on embodiment of this invention, and a balanced transmission system is demonstrated.

  FIG. 1 is a diagram showing a schematic configuration of a transmitter of a balanced transmission apparatus according to an embodiment of the present invention. The transmitter 1 includes a line state detection device 2 that detects a state of a balanced transmission line composed of a pair of conductors W1 and W2 that are signal transmission lines, and a transmission unit that inputs transmission signal data and transmits a transmission signal. 3.

  The transmission signal output from the transmission unit 3 is sent to the conductors W1 and W2 via the line state detection device 2. The signals injected into the conductors W1 and W2 may be different from the values output from the transmitter 3 depending on the transmission impedance and transmission path impedance of the transmitter. The line state detection device 2 detects the current or voltage flowing through the conductors W1 and W2, or both levels, calculates a state detection signal indicating an unbalanced state of the transmission line, and feeds it back to the transmission unit 3. The transmission unit 3 has a function of a transmission signal control unit, and based on the fed back state detection signal, the transmission signal to be output is improved so that the balance of the signals actually transmitted to the conductors W1 and W2 is improved. Control level, ie current or voltage, or both.

  Thus, by detecting the balanced state of the transmission line at the transmitter and controlling the current or voltage of the signal sent to the transmission line, or both, the conductors W1 and W2 are actually connected to the conductors W1 and W2 according to the state of the transmission line. The transmission signal level to be transmitted can be adjusted, the common mode signal level in the transmission line can be reduced, and the balance seen from the transmitter can be improved.

  FIG. 2 is a diagram showing a schematic configuration of the receiver of the balanced transmission apparatus according to the embodiment of the present invention. The receiver 4 receives a transmission signal from the conductors W1 and W2 and outputs signal data by receiving a transmission line from the conductors W1 and W2 and a line state detection device 5 that detects the state of the balanced transmission line made up of a pair of conductors W1 and W2 that are signal transmission paths. And the receiving unit 6 that is configured. Further, the transmitter 1 has a configuration including a transmission unit 3 connected to the conductors W1 and W2 of the balanced transmission line.

  The transmission signal transmitted through the conductors W1 and W2 is input to the line state detection device 5. The line state detection device 5 detects the level of current and / or voltage flowing in from the conductors W1 and W2, or both levels, calculates a state detection signal indicating an unbalanced state of the transmission line, and sends the transmission unit 3 via the reception unit 6. To give feedback. At this time, the unbalanced component has a value as if the same signal was combined as a bias in each of the conductors W1 and W2, and thus this bias value is detected. The transmission unit 3 has a function of a transmission signal control unit. Based on the state detection signal fed back from the reception unit 6, for example, the level of the transmission signal to be output is reduced so that the bias value of the fed back in-phase component is reduced. Control.

  In this way, the balanced state of the transmission line is detected by the receiver, and by controlling the current or voltage of the signal sent to the transmission line or the signal flowing in from the transmission line, or both, according to the state of the transmission line, The reception signal level actually transmitted from the conductors W1 and W2 can be adjusted, the common mode signal level in the transmission line can be reduced, and the balance seen from the receiver can be improved.

  FIG. 3 is a diagram showing a schematic configuration of a balanced transmission system including a transmitter and a receiver according to the embodiment of the present invention. This balanced transmission system includes a transmitter 1 including a line state detection device 2 and a transmission unit 3, and a receiver 4 including a line state detection device 5 and a reception unit 6, and a pair of conductors W1 serving as signal transmission paths. , W2 is used for balanced data transmission.

  The signal data for transmission is input to the transmission unit 3 and output as a transmission signal, and is transmitted to the conductors W1 and W2 via the line state detection device 2. At this time, the signal level sent to the conductors W <b> 1 and W <b> 2 is detected by the line state detection device 2, and a state detection signal indicating an unbalanced state of the transmission line is calculated and fed back to the transmission unit 3. In the transmission unit 3, the level of the transmission signal to be output is adjusted based on the state detection signal, and is controlled so that the balance of the signals sent to the conductors W1 and W2 is improved.

  Further, the transmission signal transmitted through the conductors W1 and W2 is received by the receiving unit 6 through the line state detection device 5, and signal data is acquired and output. At this time, the signal level transmitted on the conductors W1 and W2 is detected by the line state detection device 5, and a state detection signal indicating an unbalanced state of the transmission line is calculated and fed back to the transmission unit 3 via the reception unit 6. The In the transmission unit 3, the level of the transmission signal to be output is adjusted based on the state detection signal, and thereby, the balance of the signal received by the reception unit 6 via the conductors W1 and W2 is controlled to be improved.

  Thus, by detecting the balanced state of the transmission line at the transmitter and the receiver, and controlling the current or voltage of the signal on the transmission line, or both, the transmission signal on the conductors W1 and W2 according to the state of the transmission line The level can be adjusted, the common mode signal level in the transmission line can be reduced, and the balance seen from both the transmitter and the receiver can be improved.

  Next, some embodiments of the line state detection device of the present invention used in the transmitter and receiver of the balanced transmission device and the balanced transmission system as described above will be described. The line state detection device according to the present embodiment individually detects the voltage or current in the pair of conductors constituting the transmission line, or both, and detects the state related to the balance of the transmission line by extracting the difference between them. To do. As the difference, in the case of current, the difference between the currents in the forward path and the return path may be extracted, and in the case of voltage, the in-phase portion of each voltage may be extracted. In the following embodiment, a line state detection device applied to a transmitter is exemplified, but the same can be applied to a receiver.

(First embodiment)
FIG. 4 is a diagram illustrating a basic configuration of the line state detection device according to the first embodiment of the present invention. The line state detection device of the present embodiment has impedances Z11 and Z12 inserted in series in the transmission line on the forward path side and the return path side composed of a pair of conductors W1 and W2 connected to the transmission unit 13, respectively. Yes. Further, the first detection unit 11 and the second detection unit 12 that detect the voltages of the impedances Z11 and Z12, respectively, and the forward and return currents of the outputs of the first detection unit 11 and the second detection unit 12 respectively. And a difference circuit 14 that detects a difference or a common phase of voltage. The difference circuit 14 includes an addition circuit, a subtraction circuit, and the like, and any circuit can be used as long as it can detect a difference in current or voltage in the conductors W1 and W2.

  In this structure, the 1st detection part 11 and the 2nd detection part 12 can detect the electric current which each flows through the conductors W1 and W2, by detecting the both-ends voltage of impedance Z11 and Z12, respectively. Further, the difference circuit 14 calculates the difference between the currents of the forward path and the return path of the output of the first detection unit 11 and the output of the second detection unit 12 or the in-phase component of the voltage, whereby the common between the conductors W1 and W2 is calculated. A mode current (unbalanced current) component, that is, an unbalanced component of the transmission power from the transmitter 13 can be detected.

  FIG. 5 shows a first modification of the line state detection device according to the first embodiment. The first modification is a configuration in which the transmission unit 13 is connected to the difference circuit 14 in the configuration of FIG. In this configuration, the difference circuit 14 calculates the difference between the currents in the forward path and the return path of the detection outputs of the first and second detection units 11 and 12 or the in-phase voltage, and the transmission signal transmitted from the transmission unit 13. The phase of the current or voltage of this transmission signal is compared with the current or common-mode voltage of the difference between the forward path and the return path in the conductors W1 and W2 detected by the first and second detectors 11 and 12. To do. Thereby, the direction of the common mode current can be detected together with the magnitude of the unbalanced component between the conductors W1 and W2. In addition, when comparing the phase of the current or voltage in the transmission line with the transmission signal extracted from the transmission unit 13, either the voltage or current detected by the conductor W1 or the conductor W2 instead of the transmission signal extracted from the transmission unit 13 is used. It may be used.

  Further, in the line state detection device of FIG. 5, the difference between the current in the forward path and the return path in the conductors W <b> 1 and W <b> 2 detected by the first and second detection units 11 and 12 or the in-phase component of the voltage is extracted from the transmission unit 13 The product of the current or voltage of the transmission signal may be calculated by the difference circuit 14. Thus, the amount of unbalanced current between the conductors W1 and W2 of the transmission line can be detected by the calculated value of the product, and the direction of the unbalanced current can be detected by the sign of the calculated value.

  FIG. 6 shows a second modification of the line state detection device according to the first embodiment. In the second modification, in the configuration of FIG. 4, a part of the transmission signal sent from the transmission unit 13 is input, and the phase of the current or voltage of the transmission signal is shifted and output to the difference circuit 14. The circuit P11 is provided. The phase shift circuit P11 may be either one that performs an analog phase shift using a delay element or the like, or one that performs a digital phase shift process using a digital circuit. In this configuration, the phase shift circuit P11 performs phase compensation by advancing or delaying the phase of the transmission signal extracted from the transmission unit 13. The difference circuit 14 calculates the difference between the detection outputs of the first and second detectors 11 and 12, and inputs the transmission signal phase-compensated by the phase shift circuit P11, and outputs the forward path and the return path in the conductors W1 and W2. The product of the current difference or voltage in-phase and the current or voltage of the transmission signal is calculated. Thereby, the direction and current value of the unbalanced current between the conductors W1 and W2 of the transmission line can be detected with high accuracy.

  FIG. 7 shows a third modification of the line state detection device according to the first embodiment. In the third modification, in the configuration of FIG. 4, a phase shift circuit P12 that shifts the phase of the difference between the outputs of the first and second detection units 11 and 12 calculated by the difference circuit 14, and a phase shift circuit P12. And a third detection unit 15 that inputs a part of the transmission signal transmitted from the transmission unit 13 and calculates the product of these signals. The phase shift circuit P12 may be either one that performs an analog phase shift using a delay element or the like, or one that performs a digital phase shift process using a digital circuit. In this configuration, the phase shift circuit P12 performs phase compensation by advancing or delaying the phase of the difference between the detection outputs of the first and second detection units 11 and 12 calculated by the difference circuit 14. The third detection unit 15 calculates the difference between the current or voltage in the forward path and the return path between the conductors W1 and W2 phase-compensated by the phase shift circuit P12 and the in-phase component of the voltage and the current or voltage of the transmission signal extracted from the transmission unit 13. Calculate the product. Thereby, the direction and current value of the unbalanced current between the conductors W1 and W2 of the transmission line can be detected with high accuracy.

  According to such a line state detection device of the first embodiment, the voltages at both ends of the impedances Z11 and Z12 inserted in series in the conductors W1 and W2 constituting the transmission line are respectively detected by the first and second detection units. 11 and 12 can detect the currents flowing in the conductors W1 and W2, respectively, and the difference circuit 14 can calculate the difference between these detection values to detect an unbalanced component between the conductors W1 and W2. it can.

  Further, in the difference circuit 14, the phase of the current or voltage of the unbalanced component detected in the above configuration and the current or voltage of a part of the transmission signal extracted from the transmission unit 13 is compared, or the product of both is calculated. Thus, the direction of the unbalanced current can be detected together with the value of the unbalanced component between the conductors W1 and W2 of the transmission line. Furthermore, the phase of the current or voltage of the transmission signal taken out from the transmission unit 13 or the phase of the current or voltage between the conductors W1 and W2 of the transmission line calculated by the difference circuit 14 is compensated by the phase shift circuit, and the product of these products is calculated. By calculating, the direction and absolute amount of the unbalanced component in the transmission line can be detected with high accuracy.

(Second Embodiment)
FIG. 8 is a diagram showing a basic configuration of a line state detection device according to the second embodiment of the present invention. In the line state detection device of the present embodiment, the primary side (primary winding) is inserted in series in each of the transmission line on the forward path side and the return path side including the pair of conductors W1 and W2 connected to the transmission unit 23. Current transformers T21 and T22 are provided. In addition, a first detection unit 21 and a second detection unit 22 that respectively detect voltages on the secondary sides (secondary windings) of the current transformers T21 and T22, and a first detection unit 21 and a second detection unit. And a difference circuit 24 for detecting a difference between currents in the forward path and the return path of each output. The difference circuit 24 includes an addition circuit, a subtraction circuit, and the like, and any circuit can be used as long as it can detect a difference in current or voltage in the conductors W1 and W2.

  In this configuration, the first detection unit 21 and the second detection unit 22 detect the voltages generated on the secondary sides of the current transformers T21 and T22, respectively, so that the currents flowing through the conductors W1 and W2 are transmitted through the transmission line. And can be detected in a separated state. Further, the difference circuit 24 calculates a difference between the currents in the forward path and the return path between the output of the first detection unit 21 and the output of the second detection unit 22, thereby generating a common mode current (unbalanced) between the conductors W 1 and W 2. Current) component, that is, an unbalanced component of the transmission power from the transmitter 23 can be detected.

  FIG. 9 shows a first modification of the line state detection device according to the second embodiment. The first modification is a configuration in which the transmission unit 23 is connected to the difference circuit 24 in the configuration of FIG. In this configuration, the difference circuit 24 calculates the difference between the forward and return currents of the detection outputs of the first and second detection units 21 and 22 and inputs a part of the transmission signal transmitted from the transmission unit 23. Then, the phase of the current or voltage of the transmission signal is compared with the current or voltage of the difference between the forward path and the return path in the conductors W1 and W2 detected by the first and second detection units 21 and 22. Thereby, the direction of the common mode current can be detected together with the magnitude of the unbalanced component between the conductors W1 and W2. In addition, when comparing the phase of the current or voltage in the transmission line with the transmission signal extracted from the transmitter 23, the current or voltage in the conductor W1 detected by the first detector 21 and detected by the second detector 22 Either or both of the current and voltage in the conductor W2 may be used.

  9, the difference between the currents or voltages in the conductors W1 and W2 detected by the first and second detection units 21 and 22, and the current or voltage of the transmission signal extracted from the transmission unit 23 Alternatively, the difference circuit 24 may calculate the product. Thus, the amount of unbalanced current between the conductors W1 and W2 of the transmission line can be detected by the calculated value of the product, and the direction of the unbalanced current can be detected by the sign of the calculated value.

  FIG. 10 shows a second modification of the line state detection device according to the second embodiment. In the second modification, in the configuration of FIG. 8, a part of the transmission signal transmitted from the transmission unit 23 is input, and the phase of the current or voltage of the transmission signal is shifted and output to the difference circuit 24. The circuit P21 is provided. The phase shift circuit P21 may be either one that performs an analog phase shift using a delay element or the like, or one that performs a digital phase shift process using a digital circuit. In this configuration, the phase shift circuit P21 performs phase compensation by advancing or delaying the phase of the transmission signal extracted from the transmission unit 23. The difference circuit 24 calculates the difference between the forward and return currents of the detection outputs of the first and second detection units 21 and 22, and inputs the transmission signal phase-compensated by the phase shift circuit P21, and the conductor W1, The product of the current or voltage difference at W2 and the current or voltage of the transmission signal is calculated. Thereby, the direction and current value of the unbalanced current between the conductors W1 and W2 of the transmission line can be detected with high accuracy.

  FIG. 11 shows a third modification of the line state detection device according to the second embodiment. In the third modification, in the configuration of FIG. 8, a phase shift circuit P22 that shifts the phase of the difference between the outputs of the first and second detection units 21 and 22 calculated by the difference circuit 24, and a phase shift circuit P22. And a third detection unit 25 that inputs a part of the transmission signal transmitted from the transmission unit 23 and calculates a product of these signals. The phase shift circuit P22 may be either one that performs an analog phase shift using a delay element or the like, or one that performs a digital phase shift process using a digital circuit. In this configuration, the phase shift circuit P22 performs phase compensation by advancing or delaying the phase of the difference between the detection outputs of the first and second detection units 21 and 22 calculated by the difference circuit 24. The third detection unit 25 calculates the product of the difference in current or voltage between the conductors W1 and W2 phase-compensated by the phase shift circuit P22 and the current or voltage of the transmission signal extracted from the transmission unit 23. Thereby, the direction and current value of the unbalanced current between the conductors W1 and W2 of the transmission line can be detected with high accuracy.

  According to the line state detection apparatus of the second embodiment as described above, the voltage on the secondary side of the current transformers T21 and T22 in which the primary side is inserted in series with each of the conductors W1 and W2 constituting the transmission line is set to the first. And the second detectors 21 and 22 can detect the currents flowing in the conductors W1 and W2 separately from the transmission line, and the difference circuit 24 can detect the difference between the forward and backward currents of these detected values. By calculating, the unbalanced component between the conductors W1 and W2 can be detected. In this configuration, since the detection unit for detecting the unbalanced component is provided separately from the transmission line, the influence of the detection unit on the transmission line can be eliminated, and the unbalance in the transmission line can be more accurately performed. The component can be detected.

  Further, in the difference circuit 24, the phase of the current or voltage of the unbalanced component detected by the above configuration and the current or voltage of a part of the transmission signal extracted from the transmission unit 23 is compared, or the product of both is calculated. Thus, the direction of the unbalanced current can be detected in a state separated from the transmission line along with the value of the unbalanced component between the conductors W1 and W2 of the transmission line. Further, the phase of the current or voltage of the transmission signal taken out from the transmission unit 23 or the phase of the current or voltage between the conductors W1 and W2 of the transmission line calculated by the difference circuit 24 is compensated by the phase shift circuit, and the product of these is calculated. By calculating, the direction and absolute amount of the unbalanced component in the transmission line can be detected with higher accuracy.

(Third embodiment)
FIG. 12 is a diagram showing a configuration of a line state detection device according to the third embodiment of the present invention. The line state detection device according to the present embodiment has impedances Z31 and Z32 having one end connected to each of the transmission lines on the forward path side and the return path side composed of a pair of conductors W1 and W2 connected to the transmission unit 33. doing. The other ends of these impedances Z31 and Z32 are grounded. Moreover, the difference which detects the in-phase component of each output of the 1st detection part 31 and the 2nd detection part 32 which each detects the voltage of impedance Z31 and Z32, and the 1st detection part 31 and the 2nd detection part 32 And a circuit 34. The difference circuit 34 includes an addition circuit, a subtraction circuit, and the like, and any circuit can be used as long as it can detect a voltage difference between the conductors W1 and W2.

  In this configuration, the first detection unit 31 and the second detection unit 32 detect the voltages with respect to the predetermined reference potential (ground potential) in the conductors W1 and W2 by detecting the voltages across the impedances Z31 and Z32, respectively. can do. Further, the difference circuit 34 calculates a common mode voltage (unbalanced voltage) component between the conductors W1 and W2 by calculating the in-phase component of the output of the first detection unit 31 and the output of the second detection unit 32, that is, The unbalanced component of the transmission power from the transmission unit 33 can be detected.

  According to such a line state detection device of the third embodiment, the first and second detection units detect the voltages at both ends of the impedances Z31 and Z32, each having one end connected to each of the conductors W1 and W2 constituting the transmission line. By detecting with 31 and 32, each voltage with respect to the predetermined reference potential in the conductors W1 and W2 can be detected, and by calculating the in-phase component of these detected values by the difference circuit 34, the unbalanced component between the conductors W1 and W2 Can be detected.

  In the first to third embodiments, the unbalanced component between the conductors W1 and W2 may be detected using the transmission signal transmitted from the transmission unit in consideration of the output timing of the transmission signal. Good. For example, when the transmission signal is not output, the operation of the detection unit and the difference circuit is stopped, or the output of the difference circuit is turned off to detect the unbalanced component between the conductors W1 and W2 during non-transmission. Output can be excluded.

  As described above, according to the present embodiment, the balanced state of the transmission line in the balanced transmission system can be detected, and based on the detection result, the level of the transmission signal sent to the transmission line is adjusted, for example, to balance the transmission line. The state can be controlled and the balance can be improved. Thereby, leakage power from the transmission line to the outside can be reduced, and deterioration of data transmission characteristics and interference with others can be suppressed. For example, when applied to a balanced transmission system such as a power line communication system using a power line as a transmission line, a more remarkable effect can be obtained.

  The present invention has an effect that it is possible to detect a balanced state of a transmission line in a balanced transmission system that performs data transmission using a pair of conductors. It can be controlled based on the detection result, and has the effect of improving the balance, and is useful for a line state detection device in a balanced transmission system, and a transmission device and a reception device of a balanced transmission system including the same. It is.

The figure which shows schematic structure of the transmitter of the balanced transmission apparatus which concerns on embodiment of this invention. The figure which shows schematic structure of the receiver of the balanced transmission apparatus which concerns on embodiment of this invention. The figure which shows schematic structure of the balanced transmission system provided with the transmitter and receiver which concern on embodiment of this invention. The figure which shows the basic composition of the track | line state detection apparatus which concerns on the 1st Embodiment of this invention. The figure which shows the 1st modification of the track | line state detection apparatus which concerns on 1st Embodiment. The figure which shows the 2nd modification of the track | line state detection apparatus which concerns on 1st Embodiment. The figure which shows the 3rd modification of the track | line state detection apparatus which concerns on 1st Embodiment. The figure which shows the basic composition of the track | line state detection apparatus which concerns on the 2nd Embodiment of this invention. The figure which shows the 1st modification of the track | line state detection apparatus which concerns on 2nd Embodiment. The figure which shows the 2nd modification of the track | line state detection apparatus which concerns on 2nd Embodiment. The figure which shows the 3rd modification of the track | line state detection apparatus which concerns on 2nd Embodiment. The figure which shows the structure of the track | line state detection apparatus which concerns on the 3rd Embodiment of this invention. The figure which shows an example of the transmission part and transmission line of the conventional balanced transmission apparatus

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transmitter 2, 5 Line state detection apparatus 3, 13, 23, 33 Transmission part 4 Receiver 6 Reception part 11, 12, 15, 21, 22, 25, 31, 32 Detection part 14, 24, 34 Difference circuit T21 , T22 Current transformer W1, W2 Conductor Z11, Z12, Z31, Z32 Impedance P11, P12, P21, P22 Phase shift circuit

Claims (16)

A line state detection device for detecting a state of a transmission line in a balanced transmission system that performs data transmission using a pair of conductors,
Individual detection means for detecting the current flowing in the conductor and / or the voltage of the conductor for each conductor;
A line state detection device comprising: an unbalanced component calculation unit that obtains a difference in current for each conductor detected by the individual detection unit, a difference in voltage for each conductor, or both. The line state detection device according to claim 1,
The pair of conductors is a line state detection device which is a power line. The line state detection device according to claim 1 or 2,
The individual detection means is a line state detection device including current detection means for detecting a current flowing through the conductor for each conductor. The line state detection device according to claim 3,
The current detection means is a line state detection device including an impedance inserted in series with each of the pair of conductors and a voltage detection unit for detecting a voltage at both ends of the impedance. The line state detection device according to claim 3,
The current detection means includes a current transformer in which a primary winding is inserted in series in each of the pair of conductors, and a current detection unit that detects a secondary winding current or voltage of the current transformer. . The line state detection device according to claim 1 or 2,
The individual detection means is a line state detection apparatus including voltage detection means for detecting a voltage with respect to a predetermined reference potential in the conductor for each conductor. The line state detection device according to claim 1 or 2,
The unbalanced component calculation unit is a line state detection device that obtains at least one of the difference between the forward and return currents for each conductor and the in-phase component of the voltage for each conductor as the difference. The line state detection device according to any one of claims 1 to 7,
The unbalanced component calculation unit is a line state detection device that calculates the magnitude and direction of the unbalanced component between the pair of conductors based on the difference. The line state detection device according to claim 8,
The unbalanced component calculating means is a line state detection device that performs phase comparison between a transmission signal output to the conductor or a current or voltage in the conductor and a current difference or an in-phase voltage component in a forward path and a return path in the conductor. The line state detection device according to claim 8,
The unbalanced component calculation unit is a line state detection device that calculates a product of a transmission signal to be output to the conductor or a current or voltage in the conductor and a current difference or an in-phase voltage component in a forward path and a return path in the conductor. The line state detection device according to claim 9 or 10,
A line state detection device comprising phase shift means for adjusting a phase of a transmission signal to be output to the conductor or a current or voltage in the conductor and a current difference or in-phase voltage component of a forward path and a return path in the conductor. A transmission device for use in a balanced transmission system that performs data transmission using a pair of conductors,
A transmission apparatus provided with the transmission side line state detection apparatus which consists of a line state detection apparatus as described in any one of Claims 1 thru | or 11. The transmission device according to claim 12, wherein
A transmission apparatus comprising a transmission signal control unit for controlling a transmission signal output to the conductor based on an output of the transmission-side line state detection apparatus. A receiving device used in a balanced transmission system that performs data transmission using a pair of conductors,
A reception-side line state detection device comprising the line state detection device according to any one of claims 1 to 11,
A receiving apparatus comprising: a line state output unit that outputs a state detection signal indicating a line state of the transmission line based on an output of the receiving side line state detecting apparatus. A transmission device for use in a balanced transmission system that performs data transmission using a pair of conductors,
A transmission apparatus comprising a transmission signal control unit that controls a transmission signal output to the conductor based on the state detection signal output from the reception apparatus according to claim 14. A balanced transmission system that performs data transmission using a pair of conductors,
A transmission device comprising: a transmission-side line state detection device comprising the line state detection device according to any one of claims 1 to 11; and a transmission signal control unit that controls a transmission signal output to the conductor;
A reception side line state detection device comprising the line state detection device according to any one of claims 1 to 11, and a state detection signal indicating a line state of the transmission line based on an output of the reception side line state detection device. A receiving device including a line state output unit for outputting,
The transmission signal control unit is a balanced transmission system that controls a transmission signal output to the conductor based on an output of the transmission-side line state detection device and the state detection signal output from the reception device.

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