KR200341860Y1 - Apparatus for transmitting serial digital video signal through transmission line - Google Patents

Abstract

The present invention relates to a device for transmitting a serial digital video signal, and more particularly to a system suitable for transmitting the signal over a transmission line with low frequency noise.

According to a preferred embodiment of the present invention, in the apparatus for transmitting a serial digital video signal through a transmission line, receiving the serial digital video signal output from the transmission device of the preceding through the first transmission line, A first isolator circuit which cuts off a DC component of a signal and transmits the AC component; A receiver for restoring an original parallel signal with respect to a serial digital video signal input from said first isolator circuit; And a transmitter for converting the reconstructed parallel video signal back to serial and transmitting it to a transmission device at a later stage through a second transmission line.

Description

A device for transmitting serial digital video signals through a transmission line {APPARATUS FOR TRANSMITTING SERIAL DIGITAL VIDEO SIGNAL THROUGH TRANSMISSION LINE}

The present invention relates to a device for transmitting a serial digital video signal, and more particularly to a system suitable for transmitting the signal over a transmission line with low frequency noise.

Recently, information systems have been installed in tracked vehicles such as subways, trains or railway vehicles, and information such as station information (eg, getting on and off stations), news, sports, stock market, economics, weather forecasts, etc. Still images, video, etc.).

1 shows an example of such an information system for a tracked vehicle.

The first tracked vehicle 101 is provided with a broadcast server 111, which broadcast-receives video / audio information wirelessly from an access point 109, which is installed at appropriate intervals, which is serially digital video. The signal is converted into a signal and transmitted to the information display device 119 provided for each track vehicle.

In general, these serial digital video signals are high frequency signals ranging from hundreds of MHz to several GHz, so if they are transmitted as they are, they cannot be transmitted due to severe attenuation. Reference numerals 113, 115, and 117 are repeater and distributors installed to solve such a problem. The repeater / divider 113 is connected to the transmission device of the front end through the transmission line, and the signal received from the transmission device provided in the broadcast server 111 in the embodiment of FIG. 1 to output a signal of the serial digital video signal standard. The image data is restored to a parallel video signal and distributed to the plurality of screen displays 119. In addition, the repeater and divider 113 transmits the serial digital video signal received from the front end to the repeater and divider 115 at a later stage through a transmission line. Reference numeral 123 denotes a repeater for transmitting a video / audio signal between the first tracked vehicle 101 and the second tracked vehicle 103. Reference numeral 121 denotes a junction box for connecting jumper cables.

By the way, in such an information system for track vehicles, for example, power supplied through a current collector (127) provided for every four track vehicles is closed via via an energization path such as (chassis-wheel-rail). Will form. However, due to differences in energization paths or vibrations during driving, serious deviations occur in the ground potential level for each passenger vehicle, which appears as severe low frequency noise in the transmitted signal.

This deviation can reach tens of volts in severe cases, far beyond the range allowed by digital serial bitstream transmission specifications such as the TMDS specification. To solve this problem, there is a way to separate the ground of all equipment such as repeater, distributor, monitor, etc. from the chassis, but it is very expensive and has its own limitations.

Another good way to solve this circuit is by differential transmission. Referring to FIG. 2, the transmission driver 201 is configured with respect to an input serial digital video signal, the first signal (D +) 203 coded by a predetermined method (eg, Manchester encoding, 8b / 10b encoding), and A second signal (D-) 205 coded with data inverted in each data phase of the first signal is converted and transmitted. The transmission driver 201 transmits the first signal (D +) 203 through the first transmission line 207 and the second signal (D-) 205 through the second transmission line 209. Send. Then, the reception driver 215 determines the level of each received data from the difference between the first signal (D +) 203 and the second signal (D−) 205. Unexplained reference numerals 211 and 213 denote termination resistors for impedance matching to prevent feedback of signals, respectively.

According to the above-described differential transmission method, since the communication environments of the first transmission line 207 and the second transmission line 209 are almost the same, the common mode noise can be completely blocked in theory. However, if the ground voltage between the transmitter and the receiver is very different, such as in a communication environment of a tracked vehicle, the level of the received first signal (D +) 203 and second signal (D−) 205 may be If the receiver is out of the operating voltage range, accurate level determination is impossible or difficult only by the above differential transmission method.

In this situation, the present applicant has devised a transmission apparatus that can solve all the problems in transmitting a serial digital video signal through a transmission line in which low frequency noise is severe. That is, the serial digital video signal transmission device according to the present invention performs perfect blocking on the DC component and passes the AC component, thereby minimizing the influence of severe low frequency noise.

Of course, as another solution, photocoupling can be employed to completely isolate the transmitting and receiving ends in circuit. However, since the photoelectric device having the switching characteristic of the several GHz band is very expensive, such a light transmission method is expensive.

The object of the present invention is to provide a serial digital video signal transmission apparatus capable of minimizing the effects of serious low frequency noise.

Furthermore, another object of the present invention is to provide a serial digital video signal transmission device capable of completely blocking the DC component of a serial digital video reception signal and allowing the AC component to pass, thereby minimizing the effects of serious low frequency noise. .

1 is a diagram illustrating an example of an information providing system for a tracked vehicle.

2 is a diagram for explaining a differential transmission scheme.

3 is a diagram illustrating a configuration of an apparatus for transmitting a serial digital video signal through a transmission line.

According to a preferred embodiment of the present invention for achieving the above object, in the apparatus for transmitting a serial digital video signal through a transmission line, the serial digital video signal outputted from the preceding transmission device to the first transmission line A first isolator circuit which receives through and cuts off a DC component of the received signal and transmits an AC component; A receiver for restoring an original parallel signal with respect to a serial digital video signal input from said first isolator circuit; And a transmitter for converting the reconstructed parallel video signal back to serial and transmitting it to a transmission device at a later stage through a second transmission line.

Accordingly, the serial digital video signal transmission apparatus according to an embodiment of the present invention is implemented as a repeater for retransmitting a signal received from a front end to a rear end, and a serial digital video signal in which a DC component and an AC component are superpositioned. By blocking the direct current component and passing the alternating current component, it is possible to minimize serious low frequency noise, such as unstable reference voltage for determining a received signal.

According to a further aspect of the present invention, when detecting an error, at least one of the receiver and the transmitter outputs an error report signal; Select one of the serial digital video signal output from the transmitter and the serial digital video signal before being input to the first isolator circuit, and transmit the selected one to the next transmission device through the second transmission line. A switch for transmitting a serial digital video signal before being input to the first isolator circuit to a subsequent transmission device through the second transmission line when a signal or a power supply error signal from the power supply unit is generated. It is characterized in that the configuration.

Accordingly, even when an error occurs inside the serial digital video signal transmission device, the signal can be bypassed and transferred to the next stage.

Furthermore, according to an additional aspect of the present invention, the second isolator circuit is connected to the node of the second transmission line side, the second isolator circuit for blocking low-frequency noise flowing into the transmitter from the second transmission line; It features.

Accordingly, strong low frequency noise (such as a strong current of a railroad train, a vibration of a motor, etc.) flowing through the second transmission line connected to the transmitter side is blocked in a circuit, thereby protecting the transmission device.

According to another aspect of the present invention, a transmission device according to an embodiment of the present invention, in the device for transmitting a serial digital video signal via a transmission line, the serial digital video signal output from the previous transmission device A first isolator circuit which receives through a first transmission line, cuts off a DC component of the received signal and transmits an AC component; A receiver for restoring an original parallel video signal with respect to the serial digital video signal input from said first isolator circuit; A screen display driver for converting the restored parallel video signal into a form suitable for screen display; And a screen display for displaying the converted digital video signal on the screen.

Accordingly, the serial digital video signal transmission apparatus according to an embodiment of the present invention is implemented as a divider for distributing a signal received from a front end to a screen display, and the serial digital video in which a DC component and an AC component are superpositioned. By blocking the direct current component and passing the alternating current component to the signal, it is possible to minimize serious low frequency noise, such as unstable reference voltage for determining the received signal.

The foregoing and further aspects of the present invention will become more apparent through the following embodiments. Hereinafter, the present invention will be described in detail with reference to the preferred embodiments described with reference to the accompanying drawings so that those skilled in the art can easily understand and reproduce.

3 is a diagram illustrating a configuration of an apparatus for transmitting a serial digital video signal through a transmission line according to a preferred embodiment of the present invention. Hereinafter, a description will be given with reference to FIG. 1.

As shown in FIG. 3, the transmission device according to the preferred embodiment of the present invention receives a serial digital video signal output from a previous transmission device (not shown) through the first transmission line 331. A first isolator circuit 303 which cuts off a DC component of the received signal and transmits an AC component; A receiver (305) for restoring an original parallel signal with respect to a serial digital video signal input from said first isolator circuit (303); And a transmitter 307 for converting the restored parallel video signal back to serial and transmitting it to a transmission device (not shown) at a later stage via the second transmission line 333.

In the present invention, the forward transmission device refers to a device for transmitting serial digital video signals to a rear end connected through a transmission line, and the forward transmission device receives serial digital video signals from a front end connected through a transmission line. Says the device. The front and rear transmitting apparatuses may be the broadcast server 111, the repeater and distributor 113, 115, and 117 and the repeater 123 of FIG. 1.

The first isolator circuit 303 receives a serial digital video signal output from the transmission device of the previous stage through the first transmission line 331, cuts off the DC component of the received signal and transmits the AC component. As a result, severe low frequency noise such as blocking a direct current component and allowing an alternating current component to pass through a series of digital video signals in which a direct current component and an alternating current component are superposed, resulting in an unstable reference voltage for determining a received signal. Can be minimized. Meanwhile, the first isolator circuit may be implemented as a differential transformer. That is, the low frequency component is not transmitted (passed) from the primary side to the secondary side, and only the high frequency component containing the main data is transmitted (passed) to the secondary side. Such a transformer circuit is generally used in a communication circuit using a differential signal driving method, and thus can be easily implemented by those skilled in the art.

The receiver 305 restores the original parallel signal to the serial digital video signal input from the first isolator circuit 303. In addition, the receiver 305 converts a serial digital video signal into an original parallel signal and compensates for signal delay or distortion through oversampling.

The transmitter 307 converts the restored parallel video signal back into a serial signal and transmits the converted parallel video signal to a subsequent transmission device through the second transmission line 333. In other words, the transmitter 307 converts the reconstructed parallel video signal back to serial digital bit stream data and outputs the differential drive through Manchester encoding or 8b / 10b encoding.

By the operation of the receiver 305 and the transmitter 307 described above, the serial digital video signal transmission apparatus according to an embodiment of the present invention is implemented as a repeater for retransmitting the signal received from the front end to the rear end (in FIG. 123). In addition, the first isolator circuit 303 connected to the front end of the receiver 305 blocks the DC component and passes the AC component to the serial digital video signal in which the DC component and the AC component are superpositioned. Accordingly, it is possible to minimize serious low frequency noise, such as unstable reference voltage for determining the received signal.

According to a further aspect of the present invention, when an error is detected, at least one of the receiver 305 and the transmitter 307 outputs an error report signal (see 321 and 323); Any one of a serial digital video signal output from the transmitter 307 and a serial digital video signal before being input to the first isolator circuit 303 is selected to be connected to the rear end through the second transmission line 333. When the error report signal or the power supply error signal 327 from the power supply unit 319 is generated, the serial digital video signal before being input to the first isolator circuit 303 is transmitted to the transmission device. It is characterized in that it further comprises; a switcher for transmitting to the transmission device of the rear end via the transmission line 333.

Even if an error occurs inside a particular transmission device, the serial digital video signal must continue to be transmitted to the subsequent transmission device. The switcher 301 is to prepare for an error of a specific transmission device itself. Accordingly, the switch 301 receives the error signals 321, 323, 325, and 327 from various components inside the transmission apparatus. For example, the error report signal 325 may be input from the receiver 305, the transmitter 307, the power supply unit 319, and the screen displays 313 to 317. When an error signal is reported, the switch 301 bypasses the signal from the front end and transfers the signal to the rear end as it is.

According to a further aspect of the present invention, a second isolator circuit connected to a node on the side of the second transmission line 333 to block low frequency noise flowing into the transmitter 307 from the second transmission line 333 ( 309); characterized in that it further comprises.

The second isolator circuit 309 circuit-blocks strong low frequency noise (such as a strong current of a railroad train, a vibration of a motor, etc.) flowing through the second transmission line 333 connected to the transmitter 307 side. It is to protect the transmission device. The second isolator circuit 309 can be implemented with a known transformer circuit.

According to another aspect of the present invention, a transmission device according to an embodiment of the present invention, by receiving a serial digital video signal output from a transmission device (not shown) of the front end through the first transmission line 331, A first isolator circuit 303 which cuts off a DC component of the received signal and transmits an AC component; A receiver (305) for restoring an original parallel video signal with respect to the serial digital video signal input from said first isolator circuit (303); A screen display driver (311) for converting the restored parallel video signal into a form suitable for screen display; And screen displays 313 to 317 for screen displaying the converted digital video signal.

According to an embodiment of the present invention, the screen indicators 313 to 317 may be screen indicators for an analog RGB signal or a signal of a Low Volltage Differential Signaling (LVDS) standard. In the case of the analog RGB signal, the screen display driver 311 converts the restored parallel video signal into an analog form and outputs it. In the case of a signal of LVDS standard, the screen display driver 311 converts the restored parallel video signal into LVDS standard and outputs it.

By the operations of the receiver 305, the display driver 311 and the screen display (313, 315, 317) described above, the serial digital video signal transmission apparatus according to an embodiment of the present invention screens the signal received from the front end Implemented as a distributor that passes to the indicator. In addition, the first isolator circuit 303 connected to the front end of the receiver 305 blocks the DC component and passes the AC component to the serial digital video signal in which the DC component and the AC component are superpositioned. Accordingly, it is possible to minimize serious low frequency noise, such as unstable reference voltage for determining the received signal.

Meanwhile, according to a preferred embodiment of the present invention, the above-described repeater (first isolator 303, receiver 305, transmitter 307, etc.), distributor (first isolator 303, receiver 305, screen) It is natural that the configuration of the display driver 311 and the screen displays 313, 315, and 317 are combined so that the transmission device can operate as a repeater and a divider (113, 115, and 117 of FIG. 1).

As described above, according to the present invention, a serial digital video signal transmission device is implemented as a repeater for retransmitting a signal received from a front end to a rear end, and is applied to a serial digital video signal in which a DC component and an AC component are superpositioned. By blocking the direct current component and passing the alternating current component, it is possible to minimize serious low frequency noise such as unstable reference voltage for determining the received signal.

In addition, even when an error occurs inside the serial digital video signal transmission device, the signal can be bypassed and transferred to the next stage.

In addition, it is possible to protect the transmission device by blocking the strong low frequency noise (such as the strong current of the railroad train, the vibration of the motor, etc.) flowing in through the second transmission line connected to the transmitter side.

In addition, the serial digital video signal transmission apparatus according to an embodiment of the present invention is implemented as a divider for distributing a signal received from the front end to the screen display, the serial digital video signal superimposed (DC) and AC components By blocking the direct current component and passing the alternating current component, it is possible to minimize serious low frequency noise, such as unstable reference voltage for determining a received signal.

The present invention has been described by the embodiments with reference to the accompanying drawings, but is not to be construed as limiting, but should be construed to cover many modifications apparent from this.

Claims (4)

An apparatus for transmitting a serial digital video signal through a transmission line, A first isolator circuit for receiving a serial digital video signal outputted from a previous transmission device through a first transmission line to block a DC component of the received signal and to transmit an AC component; A receiver for restoring an original parallel signal with respect to a serial digital video signal input from said first isolator circuit; A transmitter for converting the reconstructed parallel video signal back into serial and transmitting it to a transmission device at a later stage through a second transmission line; Apparatus for transmitting a serial digital video signal via a transmission line comprising a. The method according to claim 1, When detecting an error, at least one of the receiver and the transmitter outputs an error report signal; Select one of the serial digital video signal output from the transmitter and the serial digital video signal before being input to the first isolator circuit, and transmit the selected one to the next transmission device through the second transmission line. A switch for transmitting a serial digital video signal before being input to the first isolator circuit to a subsequent transmission device through the second transmission line when a signal or a power supply error signal from the power supply unit is generated; Apparatus for transmitting a serial digital video signal via a transmission line, characterized in that further comprises. The method according to claim 2, A second isolator circuit connected to a node on the second transmission line side to block low frequency noise introduced from the second transmission line to the transmitter; Apparatus for transmitting a serial digital video signal via a transmission line, characterized in that further comprises. An apparatus for transmitting a serial digital video signal through a transmission line, A first isolator circuit for receiving a serial digital video signal outputted from a previous transmission device through a first transmission line to block a DC component of the received signal and to transmit an AC component; A receiver for restoring an original parallel video signal with respect to the serial digital video signal input from said first isolator circuit; A screen display driver for converting the restored parallel video signal into a form suitable for screen display; A screen display for displaying the converted digital video signal; Apparatus for transmitting a serial digital video signal via a transmission line comprising a.