KR19990009475A - Broadband signal transmitter - Google Patents

Abstract

end. The technical field to which the invention described in the claims belongs

Broadband signal transmission device.

I. The technical problem to be solved by the invention

A lowpass filter is installed in place of the bridge tap to connect the home telephone to impedance matching to eliminate distortion of the broadband signal.

All. Summary of Solution of the Invention

A subscriber line device that simultaneously implements telephone and video services using a telephone line has a low pass for impedance matching through broadband connection that directly connects to the telephone line to provide video service, and voice band filtering at the bridge tap of the telephone line. And a telephone that provides the telephone service through a filter and a low pass filter.

la. Important uses of the invention

It is used for wideband signal transmission by telephone line.

Description

Broadband signal transmitter

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wideband signal transmission apparatus using a telephone line, and more particularly, to a wideband signal transmission apparatus capable of simultaneously providing a telephone and a broadband service through impedance matching on a bridge step of a home telephone line.

In the existing telephone line in each home, several secondary lines are connected to one main inlet in the form of a bridge. Such a structure is not a problem for simply providing a telephone service using a low frequency band. However, as in the structure of FTTC (Fiber To The Curb), video and audio signals are sent to a certain area (RT; local device) by using optical paths, and after that, VDSL (Very high speed) is used to transmit the signals by using a conventional telephone line. When using the digital subscriber line method, the video signal caused by the home bridge tap is broken. This is a phenomenon caused by mismatching of impedance in the bridge tap because the video signal uses a high frequency band.

The existing method for solving the above problems is to install a terminal device for broadband service at the first entrance of the subscriber line (telephone line) in the home and separate the telephone signal and the broadband signal by a decoupler in the terminal device. It was a way of using.

Hereinafter, a configuration diagram of the existing scheme will be described with reference to FIG. 1.

First, by receiving a signal from the first wiring terminal 11 in the premises and connecting to the broadband terminal 12, by using the discriminator 13 in the broadband terminal 12 to separate only the telephone signal to the first wiring terminal, the telephone service and broadband service Implemented to receive at the same time.

However, even in the above case, a problem occurs. In this case, the broadband subscriber had to find the location of the first wiring terminal when the device was installed, that is, when the broadband terminal was installed, and had to experience the inconvenience of connecting home wiring by connecting the broadband terminal to a separate wiring. In addition, if the location of the maximum wiring terminal fails to determine the inconvenience of having to replace the wiring in the home.

Accordingly, an object of the present invention is to provide a broadband signal transmission apparatus capable of simultaneously supporting a telephone and a broadband service using a telephone line.

A subscriber line apparatus for simultaneously implementing a telephone and video service using a telephone line for achieving the above object includes a broadband terminal for directly connecting to the telephone line to provide the video service, and a voice band at a point where a bridge tap occurs on the telephone line. And a low pass filter for impedance matching through filtering, and a telephone to provide the telephone service through the low pass filter.

1 is an installation configuration of a broadband home terminal according to the prior art.

2 is a block diagram of an FTTC using the VDSL scheme according to the present invention.

3 illustrates the frequency bands used for VDSL signals in accordance with the present invention;

Figure 4 is a view showing an example of installing a low pass filter at the home bridge tap point in accordance with the present invention.

5A, 5B, 5C, and 5D show a circuit diagram and characteristics of a low pass filter installed on an indoor bridge tap according to the present invention;

Figure 6 shows examples of low pass filter installation according to the broadband terminal connection position according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a diagram illustrating a configuration of an FTTC using a VDSL transmission scheme according to the present invention.

The mother station (CT) 21 provides a wideband signal to the local station (RT) 22 through an optical cable 25, and the local station unit (RT) 22 transmits a wideband signal to the indoor broadband terminal (STT0P BOX) through an existing telephone line 24. to provide. The broadband signal is an upstream signal that a subscriber requests for service to the mother station CT 21 and a down stream corresponding to various services provided to the subscriber station by the mother station CT 21. ) Signal.

Here, the frequency band where signals (telephone signal and upstream) carried on the telephone line coming into the house and downstream (for example, VOD; video on demand) provided to the mother station CT 21 in the house are used The accompanying drawings will be described with reference to FIG. 3.

The telephone signal band occupies a low frequency band (0-84 KHz), the frequency band corresponding to the downstream signal is from 5 MHz to 25 MHz, and the frequency band corresponding to the upstream signal occupies a high frequency band of less than 30 MHz. . Here, the frequency modulation of the downstream signal uses a 16CAP (carrerless amplitude phase shift keying) method, and the frequency modulation of the upstream signal uses a quadrature phase shift keying (QPSK) method.

The overall configuration of the broadband signal transmission apparatus is described as above, and the following describes the broadband signal transmission in the home.

In the indoor broadband signal transmission, a low pass filter (LPF) that passes only a telephone signal to a point where an indoor bridge tap taps to prevent the wideband signal (high frequency video signal) from being broken and does not pass the video signal. Impedance matching was performed.

Then, an example of installing a low pass filter at the point where the bridge taps occur in the home will be described with reference to FIGS. 4A, 4B, and 4C of FIG. 4. The term line to be referred to in the following description of FIG. 4 refers to a master line.

4A of FIG. 4 illustrates a case where a broadband terminal 10 is connected to a start line. The broadband terminal 10 is connected to the first incoming line, and the telephones 20 are connected via the bridge tab after the broadband terminal 10. In this case, the signals carried on the first incoming line are a broadband signal and a telephone signal. Therefore, in order to transfer the broadband signal to the broadband terminal 10 without loss, the low pass filter 30 is installed immediately after the connection terminal of the broadband terminal 10.

4B of FIG. 4 illustrates a case where a broadband terminal 10 is connected to a termination line. The broadband terminal 10 is connected to a termination line, and the telephones 20 are connected by a bridge tab in front of the broadband terminal 10. In this case, in order for the broadband signal from the start line to be transmitted to the broadband terminal 10 without distortion, impedance matching must be performed at the bridge tap point to which the telephones 20 are connected. Therefore, a low pass filter 30 is installed in each section where the bridge taps are connected to connect the telephones 20.

4C of FIG. 4 illustrates a case where a broadband terminal (STB) 10 is connected to an intermediate line. The broadband terminal 10 is connected to an intermediate line, and a plurality of telephones 20 are connected by giving bridge tabs to the front and rear lines of the broadband terminal 10. In order to transmit the wideband signal to the subscriber station without distortion, impedance matching is performed by installing a low pass filter 30 at each bridge tap.

However, the above case refers to a case where the user knows the connection position of the broadband terminal 10. In fact, subscribers are unaware of where the first incoming line or terminating line is, so simply implement a low pass filter 30 for impedance matching at each telephone connection terminal, i.e. telephone connection bridge tap point.

Here, the circuit diagrams and characteristic diagrams of the low pass filter installed to solve the impedance mismatch caused by the disabled bridge bridge tap for simultaneously serving the broadband signal and the telephone signal using the telephone line are shown in FIGS. 5A, 5B, 5C, This will be described in detail with reference to 5d. In addition, the low pass filter should be designed for VDSL.

FIG. 5A is a circuit diagram of a low pass filter for a VDSL signal system according to the present invention. FIG. 4B is a graph showing a characteristic curve of the low pass filter of FIG. 5A. Particularly, a cut band at 50 KHz-30 MHz. Show characteristics In addition, Figure 5c shows the passband characteristics at 70Khz-2.4Mhz, Figure 5d shows the passband characteristics at 50Khz-2.4Mhz.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, examples for installing the low pass filter described above on a home telephone line according to the present invention will be described in detail with reference to FIGS. 6A, 6B, and 6C of FIG. 6.

6A of FIG. 6 illustrates a case where a master line is first connected to a broadband terminal 10. That is, the lines are connected to the back end line of the broadband terminal 10 and the low pass filter 30 is connected to the end of the lines to connect the respective phones 20. In this case, normal telephone service and abnormal video service are provided. This is because impedance matching should be done on the main line with bridge taps, since in this case a low pass filter 30 is connected directly in front of the telephone 20 so that impedance mismatching occurs at the bridge tap point of the main line.

In FIG. 6B, the main line is finally connected to the broadband terminal 10, and the telephones 20 are connected by connecting a low pass filter 30 to each bridge tap point of the main line. In this case, normal telephone service and normal video service are provided. This is because all impedance matching is performed by connecting the low pass filter 30 at all bridge tap points of the main line.

In FIG. 6C, the main line is first connected to the broadband terminal 10, and only one low pass filter 30 is connected to the rear end of the broadband terminal 10 to connect a plurality of telephones 20 in parallel. . In this case, normal telephone service and normal video service are provided. This is because the telephone sets 20 are all connected to the rear end of the broadband terminal 10 so that the impedance matching may be performed immediately after the broadband terminal 10.

That is, as shown in FIG. 6, the low pass filter 30 must be installed at the bridge tap point of the master line. In other words, the impedance matching according to the low pass filter 30 must be performed in the main line to receive normal telephone service and video service.

In addition, the above examples are also described under the assumption that the broadband terminal device (SETTOP BOX) is connected to the main line. As mentioned above, the implementation of the present invention may not realize the location of the broadband terminal device. That is, the gist of the present invention is to remove the broadband signal distortion by performing impedance matching at the bridge tap point of the home telephone line, and the low pass filter for impedance matching may be connected to the bridge tap point for telephone connection.

As mentioned above, in each home, several bridge taps are placed on one main telephone line (line) to connect one telephone to each room. Such a structure causes a video signal to break when implementing an ADSL or VDSL transmission scheme using a high frequency band. Therefore, the present invention can achieve the effect of not only breaking the signal impedance but also breaking the video signal by installing a low-pass filter at the point where the bridge tap occurs while using the existing telephone line.

Claims (3)

A broadband signal transmission device for simultaneously implementing a telephone and broadband service using a telephone line, And a low pass filter for impedance matching at each bridge tap point of the telephone line for connecting a telephone. In the broadband signal transmission apparatus for simultaneously implementing a telephone and video services using a telephone line, A broadband terminal for directly accessing the telephone line and providing the video service; A low pass filter for impedance matching through voice band filtering at the point where the bridge tap of the telephone line occurs; Broadband signal transmission device characterized in that consisting of a telephone for providing the telephone service through the low pass filter. The method of claim 2, And the low pass filter is installed immediately after the broadband terminal when the telephone line is first connected to the broadband terminal.