JP2009165043A - Asymmetric full-duplex transmission device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide "an asymmetric full-duplex transmission device" capable of absolutely transmitting a full-duplex vertically-asymmetric signal by an inexpensive device by the use of a shielded differential transmission channel comprising two signal lines. <P>SOLUTION: A first signal is transmitted by a differential signal with the two signal lines and received by a receiving part by the use of the shielded signal transmission channel comprising two signal lines and crusted conductive wires for covering them. The other signal is modulated by an SS modulation part and outputs it in common mode to the two signal lines through a first differential mode choke at the differential signal receiving part side of the two signal lines. The signal is received through a second differential mode choke, demodulated by an SS demodulating part, and inputted. A common mode choke is provided at the receiving side, the first signal is transmitted from the differential signal transmitting part to the differential signal receiving part by the two signal lines, and a second signal having a data amount smaller than that of the first signal is transmitted in the opposite direction to the SS modulated decoded signal input part by the concurrent use of the two identical signal lines. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention does not require high-speed transmission such as a camera control signal for high-speed transmission of camera data, for example, when bidirectional transmission is performed by LVDS that has been widely used as a high-speed signal transmission means of data conventionally. The present invention relates to an asymmetric full-duplex transmission apparatus that can perform full-duplex transmission without using separate lines when performing asymmetric transmission.

  Conventionally, as a high-speed signal transmission means for data, in order to perform high-speed signal transmission of several hundred Mbps or more, as an input / output signal level specification with an amplitude reduced to several hundred mV, a signal transmission means of LVDS (Low voltage differential signaling) system Is used. This method performs low-voltage differential transmission, and converts a parallel signal into a low-voltage differential serial signal for transmission. This technique solves the point that it is easily affected by noise due to the low amplitude by using differential transmission instead of single-ended transmission. This LDVS technology can reduce noise and unnecessary radiation, reduce transmission lines, and has become a standard specification for equipment internal connections, liquid crystal displays and digital interfaces.

  When bi-directional transmission of LDVS performs bi-directional transmission between two devices that transmit and receive signals by such LVDS, for example, a camera that is mounted on a vehicle and shoots outside the vehicle, and captures the photographic data of this camera. When performing the above-described LDVS bidirectional transmission with a control unit that simultaneously displays on the monitor and outputs the camera operation signal to the camera, the two-way transmission is always performed using the upper and lower separate lines. In addition to this, it can also be realized by a half-duplex transmission method in which one line is switched to vertical transmission in a time division manner.

Further, a signal line is connected between a digital camera or the like that inputs / outputs information such as an image and a terminal that is connected to the camera via a data request signal line and a data output signal line and exchanges information such as an image. Japanese Patent Application Laid-Open No. 2004-228688 discloses a technique that can control operations other than image data transmission of a camera from a terminal without increasing the number of images.
JP 2003-230041 A

  As described above, when bi-directional transmission is performed by LVDS used as a high-speed signal transmission means of data, a method of performing full-duplex transmission using separate upper and lower lines and one line for time-division transmission. There is a half-duplex transmission method for switching. For example, in transmission between a camera and a camera control unit that receives image data of the camera and transmits a control signal to the camera, the camera to the camera control unit. Transmission is mainly a video signal of 300 to 700 Mbps, and the reverse direction is only a few Kbps as a camera control signal, which is asymmetric transmission.

  For this reason, if separate lines are used between the camera and the camera control unit, the amount of camera control signal data is extremely small, resulting in excessive equipment, and the equipment is in an overhead state, resulting in a large loss in terms of cost performance. Arise. As a countermeasure, if a half-duplex transmission system that switches one line to upper and lower transmissions in time division is used, it is necessary to use a special transmission LSI for time division processing, and it is expensive because general-purpose products cannot be used. It must be a thing.

  In addition, for example, a vast number of signal lines are used in vehicles for vehicle control, etc., and their weight increases, and the signal lines are reduced in order to eliminate the influence of mutual noise as much as possible. Is important. Therefore, it is desired to develop a technique capable of transmitting and receiving data without increasing the number of signal lines as much as possible even when performing full-duplex transmission between devices.

  Accordingly, in the present invention, in transmission using two signal lines and a shield line between two devices, for example, when high-speed transmission such as a camera control signal is not required for high-speed transmission of data from the camera. In addition, when the signal transmission is asymmetrical, full-duplex transmission that can simultaneously perform signal transmission from the control unit to the device and signal transmission from the device to the control unit using a normal shielded transmission line. The main object is to provide an asymmetrical full-duplex transmission device that can be operated reliably with an inexpensive device.

  In order to solve the above problems, an asymmetric full-duplex transmission apparatus according to the present invention uses a shielded signal transmission path composed of two signal lines and a sheathed conductor covering the signal lines, and a differential signal is transmitted by the two signal lines. A differential signal transmission unit for transmitting the first signal, a differential signal reception unit for receiving the first signal from the differential signal transmission unit, and the differential signal reception unit in the two signal lines An SS modulation signal output unit that modulates an SS modulation signal by an SS modulation unit and outputs the signal to two signal lines in a common mode via a first differential mode choke, and the two signal lines An SS demodulated signal input unit which is connected to the differential signal transmitting unit side of the first signal, receives the second signal via a second differential mode choke, and demodulates and inputs the second signal, and the two signals Input to differential signal receiver from wire A common mode choke for blocking common signals, and transmitting the first signal from the differential signal transmitting unit to the differential signal receiving unit through the two signal lines, and simultaneously using the same two signal lines. A second signal having a data amount smaller than that of the first signal is transmitted from an SS modulation signal output unit to an SS modulation decoded signal input unit in a reverse direction.

  Another asymmetric full-duplex transmission apparatus according to the present invention is the above-described asymmetric full-duplex transmission apparatus, wherein each of the connection sections between the first differential mode choke and the two signal lines includes A DC cut capacitor is provided between the differential mode choke, and at each connection portion between the second differential mode choke for inputting the SS demodulated signal and two signal lines, the connection portion and the second differential mode choke are provided. And a DC cut capacitor.

  Another asymmetric full-duplex transmission apparatus according to the present invention is the above-described asymmetric full-duplex transmission apparatus, wherein the second differential mode choke connection section for inputting an SS signal in the two signal lines, and a differential signal A common mode choke for blocking a common signal input to the differential signal transmitter is provided between the transmitter and the transmitter.

  Another asymmetric full-duplex transmission apparatus according to the present invention is the asymmetric full-duplex transmission apparatus, wherein the second differential mode choke is connected to the SS signal demodulator on the ground wire grounded by the second differential mode choke, and the second differential A DC cut capacitor is provided between the mode choke and the mode choke.

  Another asymmetric full-duplex transmission apparatus according to the present invention is the asymmetric full-duplex transmission apparatus, wherein a DC power source is connected between the SS modulation unit and the first differential mode choke to connect the two signals. A DC power supply current is output to the line, and the power supply current is input from a signal line extending from the second differential mode choke to the SS demodulator.

  Another asymmetric full-duplex transmission apparatus according to the present invention is the asymmetric full-duplex transmission apparatus, further comprising a DV cut capacitor between the SS modulation unit and the DC power supply connection unit, and the second differential mode choke. In the signal line extending from the SS demodulator to the SS demodulator, a DC cut capacitor is also provided between the input portion of the power supply current and the connecting portion of the SS demodulator.

  Another asymmetric full-duplex transmission apparatus according to the present invention is the above-described asymmetric full-duplex transmission apparatus, wherein a DC is applied to each line between the common mode choke in the two signal lines and the first differential mode choke connection unit. A cut capacitor is provided, and each line between the second differential mode choke connecting portion and the differential signal transmitting portion in the two signal lines is also provided with a DC cut capacitor.

  Another asymmetric full-duplex transmission apparatus according to the present invention is the asymmetric full-duplex transmission apparatus, wherein one end of the outer skin conductor is grounded together with a circuit in the differential signal receiving section, and the other end of the outer skin conductor is Is grounded together with the circuit in the differential signal transmission unit.

  Another asymmetric full-duplex transmission apparatus according to the present invention is such that, in the asymmetric full-duplex transmission apparatus, the differential signal transmission unit transmits a signal modulated by a DC suppression modulation unit, and the differential signal reception unit Then, this is received and demodulated by the DC suppression demodulator.

  Another asymmetric full-duplex transmission apparatus according to the present invention is the asymmetric full-duplex transmission apparatus, wherein one end of the outer skin lead wire is grounded via a DC cut capacitor before reaching the differential signal receiver, The other end is grounded via a DC cut capacitor before reaching the differential signal transmitter, and an AC power source is connected between the SS modulator and the first differential mode choke to connect the two signals. An AC power supply current is output to the line, and the power supply current is input from a signal line extending from the second differential mode choke to the SS demodulator.

  Another asymmetric full-duplex transmission apparatus according to the present invention is the asymmetric full-duplex transmission apparatus, further comprising a DC cut capacitor between the AC power supply connection portion and the first differential mode choke, A DC cut capacitor is also provided between the differential mode choke and the AC power supply input unit.

  Another asymmetrical full-duplex transmission apparatus according to the present invention is the asymmetrical full-duplex transmission apparatus, wherein the first differential mode choke connection unit and the second differential mode choke for the two signal lines are connected. Each of the signal lines is provided with a DC cut capacitor adjacent to each connection portion.

  Another asymmetric full-duplex transmission apparatus according to the present invention is such that, in the asymmetric full-duplex transmission apparatus, the differential signal transmission unit transmits a signal modulated by a DC suppression modulation unit, and the differential signal reception unit Then, this is received and demodulated by the DC suppression demodulator.

  Another asymmetric full-duplex transmission apparatus according to the present invention is characterized in that, in the asymmetric full-duplex transmission apparatus, the full-duplex transmission apparatus is used for a vehicle-mounted device.

  Another asymmetric full-duplex transmission apparatus according to the present invention is the asymmetric full-duplex transmission apparatus, wherein the full-duplex transmission apparatus processes a video signal transmitted from the camera and the camera, and outputs a control signal to the camera. It is characterized by doing.

  In transmission using two signal lines and a shield line between two devices, for example, when high-speed transmission such as camera control signals is not required for high-speed transmission of data from the camera, When the top and bottom are asymmetrical, signal transmission from the control unit side to the device and signal transmission from the device to the control unit can be performed simultaneously using a shielded transmission line with a shield covering the periphery of the two normal signal lines. Full-duplex transmission that can be performed is possible, and the operation of the apparatus can be reliably performed with an inexpensive device.

  An object of the present invention is to use two signal lines and their shielded wires to reliably transmit full-duplex asymmetric signals with an inexpensive device, and to provide a shield consisting of two signal lines and a sheathed conductor covering them. A differential signal transmission unit that transmits a first signal as a differential signal through the two signal lines using an attached signal transmission path, and a differential signal that receives the first signal from the differential signal transmission unit The receiver is connected to the differential signal receiver side of the two signal lines, the SS modulation signal is modulated by the SS modulator, and the two signal lines are connected to the common mode via the first differential mode choke. The SS modulation signal output unit that outputs the signal and the differential signal transmission unit side of the two signal lines, the second signal is received via the second differential mode choke, and the SS demodulation unit receives the second signal. Demodulated SS input signal And a common mode choke for blocking a common signal input to the differential signal receiving unit from the two signal lines, and the first signal is differentiated from the differential signal transmitting unit by the two signal lines. A second signal having a data amount smaller than that of the first signal is transmitted from the SS modulation signal output unit to the SS modulation decoded signal input unit using the same two signal lines at the same time. Realized by transmitting to.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a first embodiment of the present invention. In the illustrated example, an image of a camera mounted for a vehicle is captured and displayed on a monitor between the camera and a control unit that controls the camera. An example when performing differential transmission is shown. That is, a differential signal receiver (differential Rx) 1 that receives a video signal provided on the camera control unit side (ECU side) and a differential signal transmitter (difference) that transmits a video signal provided on the camera side. Are connected to each other by two communication lines for transmitting video data by balanced transmission and a shield line that shields the outer periphery of these lines. The shield wire is grounded together with the ground electrodes of the receiving circuit and the transmitting circuit in the differential signal receiving unit 1 and the differential signal transmitting unit 2.

  The video signal from the differential signal transmission unit 2 to the differential signal reception unit 1 performs high-speed communication with a large capacity of typically 300 to 700 Mbps, and is the main data transmission on this communication line. In this transmission line, for example, a termination resistor 4 that is defined as 100Ω by the standard in LVDS transmission is provided.

  In the present invention, for example, the differential transmission unit 2 that transmits the video signal of the camera, for example, as described above, uses the transmission line that is balanced and transmitted to the differential signal reception unit 1 that receives the signal. In order to transmit a control signal from the control unit side on the vehicle side to the camera at about 1 to 16 Kbps, an unbalanced transmission path is additionally set to make signals in opposite directions. Then, SS (spread spectrum) modulation is performed on the transmission side, and SS demodulation is performed on the reception side.

  In the example shown in FIG. 1, in order to transmit a camera control signal from the camera control unit side (ECU side) to the camera side, the SS modulation signal output unit 13 outputs the camera control signal as a common transmission signal, and the SS modulation unit 9 Then, SS modulation is performed, and the signal is output to the two signal lines of the shielded differential transmission line 6 via the differential mode choke 10. SS modulation by the SS modulator 9 performs spread spectrum communication that is widely used at present, has a wide spectrum (frequency distribution), and has a low power density because power per unit frequency is reduced. Therefore, there is little possibility of interference with the other party, and there is interference tolerance. Also, even if noise is mixed during ongoing transmission, the noise is diffused at the time of restoration, so that it has a characteristic that there is little influence on communication, and a transmission line for balanced transmission of video signals as in the present invention It is particularly suitable for receiving and receiving signals in the reverse direction.

  For communication by SS modulation, the modulated information signal is added to the pseudo-noise generator and transmitted by two-phase or four-phase transfer modulation (DS type), and the frequency jumping system that hops the frequency by the pseudo-noise generator (FH method), a time jump method (TH method) that is a pulse modulation method in which a transmitter is intermittently connected by a pseudo-noise code sequence, a hybrid method using these methods in combination as appropriate, and the like. The structure is simple, and it can be made to function sufficiently with a direct spread system (DSSSS: Direct Sequential Spread Spectrum) that is easy to manufacture and inexpensive.

  In FIG. 1, the camera control signal modulated by the SS modulator 9 is output to the signal line via the differential mode choke 10. Further, the common mode choke 3 is provided on the differential signal receiving unit 1 side from the portion where the differential mode choke 10 is coupled in the shielded differential transmission path 6. In the present invention, by using the common mode choke coil and the differential mode choke as described above, it is intended to surely transmit the upper and lower signals through the same transmission path, and these choke coils will be described below. To do.

  As is well known in the signal transmission path, as shown in FIG. 5B, a differential mode (normal mode) in which signals are transmitted in opposite directions on two signal lines as shown in FIG. There is a common mode in which two signal lines transmit in the same direction, and in the common mode, a grounding GND line is provided. In such a transmission line, noise enters from noise sources as shown in each figure, and in the common mode, has a stray capacitance in the grounded portion.

  As a countermeasure against noise in the differential mode and common mode transmission paths as shown in FIG. 6, a technique of reducing noise by passing a choke coil is widely used. In this method, a differential mode choke coil is used as the choke coil in the differential mode shown in FIG. 5A, and a common mode choke coil is used as the choke coil in the common mode shown in FIG. The line direction is different.

  The operating principle of these coils is shown in FIG. That is, FIG. 4A shows a case where the winding directions of the cores are different in the common mode in which signals are transmitted in the same direction on the two signal lines, and FIG. In the differential mode in which signals are transmitted in opposite directions on the line, the winding direction with respect to the core is changed.

  In this case, as indicated by the arrow of the core in the figure, in the common mode of FIG. 10A, the magnetic flux generated in the core plays a role of a brake that blocks the current against a sudden current change. When such noise enters, the choke action can prevent noise from entering. On the other hand, in the differential mode shown in FIG. 5B, the magnetic fluxes generated in the cores cancel each other and do not affect the signals transmitted and received. Therefore, in common mode, countermeasures against noise are taken using the common mode choke as described above. In that case, the circuit diagram is shown as (c) in the figure, indicating that coils with different winding directions are used. Yes.

  On the other hand, FIG. 7D shows a case where the winding direction of the core is the same direction in the common mode in which signals are transmitted in the same direction on the two signal lines, and FIG. In the differential mode in which signals are transmitted in opposite directions on the signal line, the winding direction with respect to the core is the same direction.

  In this case, the magnetic fluxes generated in the core cancel each other out in the common mode of FIG. On the other hand, in the differential mode shown in FIG. 5E, the magnetic flux generated in the core acts as a brake to block current against sudden current changes. Therefore, when noise enters, the choke action causes the noise to be reduced. It is possible to prevent entry. Therefore, in the differential mode, noise countermeasures are performed using the differential mode choke as described above. At that time, the circuit diagram is shown as (f) in the figure, which indicates that the winding direction is the same direction.

  The SS signal from the SS modulation unit 9 in FIG. 1 is transmitted from the differential signal transmission unit 2 to the differential signal reception unit 1 via the differential mode choke 10 that performs the above operation. Output to the differential transmission line that transmits the video signal. This SS signal is demodulated by the SS demodulator 8 via a similar differential mode choke 5 provided on the camera side, and is input by the SS demodulated signal input unit 14 as a common mode transmission decoded signal, which is used as a camera control signal. . In the example of FIG. 3, a termination resistor 7 is provided in parallel with the circuit of the SS demodulator 8.

  In addition, a DC cut capacitor 11 is provided at a portion where the output from the SS modulator 9 is coupled to the signal transmission line from the differential mode choke coil 10, and the SS demodulator is branched from the signal transmission line via the differential mode choke 5. The DC cut capacitor 12 is also provided in the portion that outputs to 8. Further, the SS signal from the SS modulation unit 9 is connected to the signal line via the differential mode choke coil 10 and the DC cut capacitor 11 respectively, and the termination provided in the differential signal receiving unit 1 of the camera control unit. A common mode choke 3 is provided between the resistor 10.

  In the embodiment of FIG. 1 configured as described above, the differential video signal from the camera side to the camera control unit side is balanced and transmitted by two shielded signal lines. The camera control signal from the SS modulation signal output unit 13 on the camera control unit side is output to the differential transmission line via the differential mode choke coil 4 and the DC cut capacitor 11 as described above. The DC component is cut by the capacitor 11 and output to the signal line. Accordingly, it is possible to prevent the SS signal from being mixed into the video signal and noise from being mixed into the video signal.

  Further, the differential mode choke 10 can prevent the video signal that is differentially transmitted through the signal line from entering the camera control signal transmission system as noise by the embodiment shown in FIG. Since the differential mode choke 10 transmits the camera control signal in the common mode, the signal is not affected as shown in FIG. 7D. The functions of the DC cut capacitor 11 and the differential mode choke 10 are the same in the DC cut capacitor 12 and the differential mode choke 5 provided in the input stage of the SS demodulator 8 that receives the camera control signal.

  In the common mode choke 3 provided on the camera control unit side of the shielded differential transmission path 6, when the camera control signal is SS-modulated and enters the differential transmission path by common mode transmission as described above, this is prevented. Then, the transmission of the camera control signal to the camera side is ensured, and the camera control signal is reliably prevented from becoming a noise to the video signal by the mode of FIG. As shown in FIG. 7B, this common mode choke does not affect a normal video signal.

  As described above, in the present invention, in the transmission using two signal lines and the shield line between two devices, the high-speed transmission of the video signal from the camera as described above is similar to the control signal of the camera. When the signal transmission is asymmetrical, such as when high-speed transmission is not required, the signal transmission from the control unit to the device is performed using the normal shielded transmission line with two signal lines, and A full-duplex transmission capable of simultaneously performing signal transmission from the device to the control unit can be realized as an asymmetric full-duplex transmission apparatus that can reliably transmit without causing noise.

  The present invention can be further implemented in various modes. In the example of FIG. 1, the SS modulation signal, which is a common mode transmission signal, is transmitted to the transmission path for transmitting the video signal in the shielded differential transmission path 6. The example of preventing the influence of noise by the common mode choke 3 provided on the differential signal input unit 1 side in the camera control unit has been shown. In addition, as shown in FIG. May be provided to prevent the influence on the control circuit on the camera side. In the example shown in FIG. 2, a DC cut capacitor 12 is further provided on the signal line from the differential mode choke 5 to the SS demodulator 8.

  Further, the example shown in FIG. 3 shows an example in which a DC power supply current for the camera is transmitted to the camera side together with the camera control signal. That is, the DC power source 17 is connected to a portion that outputs an SS-modulated signal via the DC cut capacitor 20. This power supply current passes through the differential mode choke 10, the signal line of the shielded differential transmission line 6, and the differential mode choke 5 together with the SS modulation signal, and from the front side of the DC cut capacitor 22 of the signal to the SS demodulator 8, the camera power supply It outputs to the unit 18 and supplies an operating current to the camera.

  In the example shown in FIG. 3, instead of the differential mode choke 10 shown in FIGS. 1 and 2 and the DC cut capacitor 11 provided at the connection to the signal line of the operating transmission line, the connection and the common mode choke 3 A DC cut capacitor 19 is provided on each transmission line between them, and similarly, instead of the DC cut capacitor 12 provided at the connection portion between the differential mode choke 15 and the signal line of the operation transmission path, the connection portion and the differential signal transmission portion A DC cut capacitor 21 is provided in each transmission line between the two and the same operation can be performed by such a circuit. Thus, the power supply current can be supplied without using a separate line.

  Further, in the example shown in FIG. 3, the video signal of the camera is modulated by the DC suppression modulation unit 24 to suppress the DC signal, and this is transmitted from the differential signal transmission unit 2. In the differential signal receiving unit 1 that receives this, it is decoded by the DC suppression demodulating unit 23 and used as a photographed image of the camera. By previously performing modulation for suppressing the DC component on the differential signal transmitted through the differential transmission path 6, the influence of the SS modulation signal can be further reduced.

  In the example of FIGS. 1-3, both ends of the shield of the shielded transmission line 6 are connected to the differential signal receiving unit 1 and the differential signal transmitting unit 2, respectively, and installed together with the ground terminals of the circuits in each unit. Although an example has been shown, as shown in FIG. 4 for example, the shield is peeled off on the front side reaching the differential signal receiving unit 1 and the differential signal transmitting unit 2, and the shield outer DC cut capacitor 30 is provided at each end. Via the ground. In this case, a resistor that bypasses the shield outer skin DC cut capacitor 30 may be provided.

  In the example shown in FIG. 3, the power source current is supplied from the DC power source 17 to the camera. However, in the embodiment of FIG. 4, the AC power source 35 is used, and the DC cut capacitor is connected to the SS modulation output signal. 31, which is connected to the differential transmission line through the differential mode choke 10. Further, DC cut capacitors 32 and 34 are provided in the transmission line between the connection portion and the portion where the differential mode choke 5 on the camera side is connected, in proximity to each connection portion, so that the differential mode choke on the camera side is provided. A DC cut capacitor 33 is provided on the signal line before the output from 5 reaches the camera power supply 18. Further, the camera power supply 18 is grounded.

  By configuring the transmission path as described above, a problem of a ground offset having a large potential between grounds becomes prominent, especially when the present invention is applied to a vehicle-mounted camera, and the ground offset is several V. In this embodiment, an AC couple is formed throughout the transmission and reception by the arrangement of the DC cut capacitor, and the DC ground loop can be more reliably eliminated by the AC grounding of the shield shell and the supply of the AC power supply current. It can be used with peace of mind as an on-vehicle device.

  At this time, there is a concern that the S / N ratio decreases due to the formation of the AC ground loop, but high-speed transmission from the camera to the camera control unit is differential transmission, and low-speed transmission from the camera control unit to the camera is SS modulation. Therefore, the decrease in the SN ratio can be improved.

  Also in the example shown in FIG. 4, similarly to the example of FIG. 3, the video signal of the camera is modulated by the DC suppression modulation unit 24 to suppress the DC signal, and this is transmitted from the differential signal transmission unit 2. Sending. In the differential signal receiving unit 1 that receives this, it is decoded by the DC suppression demodulating unit 23 and used as a photographed image of the camera. By previously performing modulation for suppressing the DC component on the differential signal transmitted through the differential transmission path 6, the influence of the SS modulation signal can be further reduced.

1 is a system configuration diagram of an embodiment of the present invention. It is a system configuration | structure figure of the other aspect of the Example. It is a system configuration | structure figure of the further another aspect of the Example. It is a system block diagram of the other Example of this invention. It is a figure which shows the aspect of the noise of differential mode and common mode. It is a figure which shows the differential aspect of the choke coil for cutting the noise of differential mode and common mode. It is a figure which shows the differential mode with respect to the differential mode noise and the noise of a common mode of a differential mode choke and a common mode choke.

Explanation of symbols

1 Differential signal receiver
2 differential signal transmission unit 3 common mode choke 4 termination resistor 5 differential mode choke 6 shielded differential transmission line 7 termination resistor 8 SS demodulation unit 9 SS modulation unit 10 differential mode choke 11 DC cut capacitor 12 DC cut capacitor 13 SS modulation Signal output unit 14 SS demodulated signal input unit

Claims (15)

Using a shielded signal transmission line consisting of two signal lines and a sheathed conductor covering them,
A differential signal transmission unit for transmitting a first signal as a differential signal by the two signal lines;
A differential signal receiver for receiving a first signal from the differential signal transmitter;
SS connected to the differential signal receiving unit side of the two signal lines, SS modulated signal is modulated by the SS modulating unit, and outputted to the two signal lines in the common mode via the first differential mode choke A modulation signal output unit;
An SS demodulated signal input unit connected to the differential signal transmitting unit side of the two signal lines, receiving the second signal via a second differential mode choke, and demodulating and inputting the second signal by an SS demodulating unit; ,
A common mode choke for blocking a common signal input to the differential signal receiving unit from the two signal lines,
A first signal is transmitted from the differential signal transmitting unit to the differential signal receiving unit through the two signal lines, and a second data amount is smaller than that of the first signal using the same two signal lines at the same time. Is transmitted in the reverse direction from the SS modulated signal output unit to the SS modulated decoded signal input unit. In each connection part of the first differential mode choke and the two signal lines, a DC cut capacitor is provided between the connection part and the first differential mode choke,
In each connection portion between the second differential mode choke for inputting the SS demodulated signal and two signal lines, a DC cut capacitor is also provided between the connection portion and the second differential mode choke. The asymmetrical full-duplex transmission apparatus according to claim 1, wherein   A common mode choke for blocking a common signal input to the differential signal transmission unit between the second differential mode choke connection unit for inputting the SS signal and the differential signal transmission unit in the two signal lines. The asymmetric full-duplex transmission apparatus according to claim 1, further comprising:   2. The asymmetric device according to claim 1, further comprising a DC cut capacitor between a connection portion of the SS signal demodulator on a ground wire grounded by the second differential mode choke and the second differential mode choke. Full duplex transmission device. A DC power source is connected between the SS modulator and the first differential mode choke to output a DC power source current to the two signal lines;
2. The asymmetric full-duplex transmission apparatus according to claim 1, wherein the power supply current is input from a signal line extending from the second differential mode choke to an SS demodulator. A DV cut capacitor is provided between the SS modulation unit and the DC power supply connection unit,
6. The signal line extending from the second differential mode choke to the SS demodulator includes a DC cut capacitor between a portion for inputting a power supply current and a connection of the SS demodulator. Asymmetric full-duplex transmission equipment. A DC cut capacitor is provided on each line between the common mode choke and the first differential mode choke connection in the two signal lines,
6. The asymmetric full-duplex transmission according to claim 5, wherein each line between the second differential mode choke connection section and the differential signal transmission section in the two signal lines is provided with a DC cut capacitor. apparatus. One end of the outer skin lead wire is grounded together with the circuit in the differential signal receiving unit,
2. The asymmetric full-duplex transmission apparatus according to claim 1, wherein the other end portion of the outer conductor is grounded together with a circuit in the differential signal transmission unit.   The differential signal transmission unit transmits a signal modulated by a DC suppression modulation unit, and the differential signal reception unit receives the signal and demodulates it by a DC suppression demodulation unit. Asymmetric full-duplex transmission equipment. One end of the outer skin lead wire is grounded via a DC cut capacitor before reaching the differential signal receiving unit, and the other end is grounded via a DC cut capacitor before reaching the differential signal transmitting unit,
An AC power supply is connected between the SS modulator and the first differential mode choke to output an AC power supply current to the two signal lines,
2. The asymmetric full-duplex transmission apparatus according to claim 1, wherein the power supply current is input from a signal line extending from the second differential mode choke to an SS demodulator. A DC cut capacitor is provided between the AC power supply connection portion and the first differential mode choke,
11. The asymmetric full-duplex transmission apparatus according to claim 10, further comprising a DC cut capacitor between the second differential mode choke and an AC power input unit.   Each signal line between the first differential mode choke connection and the second differential mode choke for the two signal lines is provided with a DC cut capacitor adjacent to the connection. The asymmetric full-duplex transmission apparatus according to claim 10.   The differential signal transmission unit transmits a signal modulated by a DC suppression modulation unit, and the differential signal reception unit receives the signal and demodulates the signal by a DC suppression demodulation unit. Asymmetric full-duplex transmission equipment.   The asymmetric full-duplex transmission device for on-vehicle equipment according to claim 1, wherein the full-duplex transmission apparatus is used for on-vehicle equipment.   The asymmetric full-duplex transmission device for a camera according to claim 1, wherein the full-duplex transmission device processes a camera and a video signal transmitted from the camera, and outputs a control signal to the camera.

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