JP2001298470A - Data transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To transmit a data signal without its being affected by a merging noise. SOLUTION: A head end 2 has an Internet connection server 28, and the server 28 transmits a 1st outgoing data signal to a main transmission line 10 with a television signal. An in-building head end 16 is connected to the main transmission line 10. The in-building head end 16 transmits the television signal to each television terminal 22 via a sub transmission line 20. The in-building head end 16 converts the 1st outgoing data signal into a 2nd outgoing data signal transmittable via a telephone line 48 provided individually to each terminal and outputs the 2nd outgoing data signal to the telephone line 48, and converts a 1st incoming data signal sent from a personal computer 60 via the telephone line 48 into a 2nd incoming data signal transmittable through the main transmission line 10 and outputs the 2nd incoming data signal to the server 28 via the main transmission line 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transmission system for connecting an information terminal device to the Internet and a relay device used for the data transmission system, and more particularly to, for example, an in-building joint reception system using a two-way joint reception facility.

[0002]

2. Description of the Related Art In recent years, personal computers have become widespread as an example of information terminal equipment. One of the applications of personal computers that is receiving attention is connection to the Internet. One of the methods for connecting to the Internet is CATV Internet. This means that a server is provided at the head end of the two-way joint reception facility, and the downstream data signal from the server is supplied to the information terminal equipment provided at each terminal in the building using the two-way joint reception facility, The upstream data signal from the terminal device is supplied to the server in the head end via the transmission line of the two-way joint receiving facility.

[0003]

The CATV Internet has an advantage that high-speed transmission can be performed. However, since a bidirectional joint reception facility is used, an upstream data signal from a certain information terminal equipment is transmitted to a head end. While the signal is transmitted to the premises, noise from other terminals in the building is often transmitted together, and there is a problem of so-called ingress noise, in which the uplink data signal may be buried in the noise.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a data transmission system in which the transmission of data signals in a two-way joint reception facility is restricted to a certain area to reduce ingress noise, and a relay device used in the system. And

[0005]

The data transmission system according to the present invention has a head end. This headend has a server for Internet connection. The Internet downstream data signal from this server is transmitted to the main transmission path together with the television signal.
Television signals include VHF, UHF or both terrestrial television broadcast signals, satellite broadcast intermediate frequency signals, satellite communication intermediate frequency signals, or both satellite intermediate frequency signals. This system further has a relay device. The relay device is connected to the main transmission path, and transmits the television signal to each terminal via the sub transmission path. Further, the relay device is capable of transmitting a downlink data signal via a data signal transmission line individually provided for each terminal.
The signal is converted into a downlink data signal and output to the information terminal device via the data signal transmission line. The relay device converts a first upstream data signal of the Internet from the information terminal device into a second upstream data signal that can be transmitted on a main transmission path, and outputs the second upstream data signal to the server via the main transmission path.

With this configuration, between the relay device and the information terminal device, the upstream and downstream Internet data signals are transmitted separately from the data signal transmission line laid between the relay device and each information terminal device. The transmission using the two-way joint receiving facility is performed only between the repeater and the headend. Therefore, the influence of the ingress noise can be reduced without being affected by the ingress noise in the transmission from each information terminal device to the relay device.

Each data signal transmission line is a telephone line that can be connected to a public telephone line, and the second downlink data signal and the first uplink data signal correspond to the frequency band of the telephone voice signal on the public telephone line. Non-overlapping.

[0008] With this configuration, since the telephone line already laid can be used as the data signal transmission line, the laying work becomes unnecessary. Further, since the uplink and downlink data signals do not overlap with the frequency band of the telephone voice signal, they do not adversely affect telephone communication.

A relay device of a data transmission system according to the present invention has an input / output terminal to which a television signal and a first downstream data signal of the Internet are input. Further, the repeater has an output terminal connected to the sub-transmission line, and the output terminal outputs a television signal from the input / output terminal to the sub-transmission line. A downstream filter extracts a first downstream data signal from the television signal from the input / output terminal and the first downstream data signal. The first upstream data signal from each information terminal device via the data signal transmission line and the first downstream data signal of the downstream filter are input to the conversion means. The conversion means converts a first uplink data signal into a second uplink data signal that can be transmitted on the main transmission path, and converts the first downlink data signal into a second downlink data signal that can be transmitted on the data signal transmission line. The data is converted and output to the data signal transmission line. The second upstream data signal from the conversion means is supplied to the upstream filter, passes the second upstream data signal, and outputs to the input / output terminal.

According to this relay device, since the first downlink data signal transmitted through the main transmission path is extracted by the downlink filter and supplied to the conversion means, an interfering wave is hardly generated in the conversion means. The first downlink data signal can be reliably converted to the second downlink data signal and supplied to the data signal transmission line. Further, since the second upstream data signal from the conversion means is extracted by the upstream filter and supplied to the input / output terminal, only the second upstream data signal is supplied to the input / output terminal, and unnecessary signals are mainly transmitted. There is no transmission to the transmission path.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A data transmission system according to one embodiment of the present invention has a head end 2 as shown in FIG. The head end 2 has a television signal receiving antenna. As one of these antennas,
It has a terrestrial television broadcast receiving antenna 4 for receiving terrestrial television broadcast signals in the UHF band, the VHF band, or both. Further, as a receiving antenna of the television signal, it has an antenna 6 for receiving a satellite broadcast signal for receiving a satellite broadcast signal and an antenna 8 for receiving a satellite communication signal for receiving a satellite communication signal. The satellite broadcast intermediate frequency signal from the satellite broadcast receiving antenna 6 and the satellite communication intermediate frequency signal from the satellite communication receiving antenna 8 are converted by the head end 2 into a remodulated wave in a frequency band that can be transmitted through the main transmission path 10. The signal is re-modulated and transmitted on the main transmission path 10 together with the terrestrial television broadcast signal. Hereinafter, the satellite broadcast intermediate frequency signal, the satellite communication intermediate frequency signal, and the terrestrial television broadcast signal are referred to as downlink signals.

The main transmission line 10 includes, for example, a coaxial cable 11 and a plurality of bidirectional branch amplifiers 12 between them.
have. The downstream signal branched from one of these bidirectional branch amplifiers 12 is transmitted to a relay device, for example, a premises headend 16 via a bidirectional distributor 14. FIG.
Then, only one head end 16 in the ridge is shown,
In practice, many wing headends 16 are provided. The down signal from the head end 16 in the building is divided into four by, for example, a four distributor 18 and transmitted to each room of one building via the sub-transmission line 20. The sub-transmission line 20 also
For example, it is constituted by a coaxial cable. A television terminal 22 is interposed in the sub-transmission line 20 corresponding to each room. From these, downlink signals are transmitted to the television receiver 26 via the home terminal device 24.

The head end 2 is provided with a server 28. The server 28 is connected to a provider (not shown) via a transmission line for Internet connection, for example, an optical fiber or a high-speed dedicated line, and can transmit and receive Internet data signals to and from the provider. Although not shown, the downstream data signal of the Internet from this provider is transmitted to the first end data signal of a frequency band that can be transmitted on the main transmission line 10, for example, a mid-band or super-high band frequency band, at the head end 2. Has been converted. Of course, the first downlink data signal has a non-overlapping frequency with the above-described downlink signal as shown in FIG.

The first downlink data signal is transmitted to the main transmission line 10
Is transmitted to the ridge head end 16. The in-building head end 16 transmits Internet data signals using an ADSL (Asymmetric Digital Subscriber Line) access system.

As shown in FIG. 2, the in-building head end 16 has an input / output terminal 30 to which a downstream signal and a first downstream data signal are supplied from the main transmission line 10. The downstream signal and the first downstream data signal are supplied to the amplifier 34 via the mixing / demultiplexing device 32, and after being amplified there, are supplied to the output terminal 38 via the 1 branch device 36. The output terminal 38 is connected to the sub-transmission line 20, and a downstream signal is output to each television terminal 22 via the sub-transmission line 20. Therefore, the downstream signal can be received by each television receiver 26 via the home terminal device 24. On the other hand, the branch terminal of the 1 branch unit 36 is connected to a downstream extraction filter 40 having a pass band capable of extracting the first downstream data signal. This downstream extraction filter 40
Is output to the modem 42 which is a part of the conversion means.

The modem 42 demodulates the first downlink data signal into a downlink data signal and supplies the demodulated data signal to a multiplexing HE device (multiplexing headend device) 44 which forms a part of the conversion means.
Since only the first downstream data signal extracted by the downstream extraction filter 40 is supplied to the modem 42, the modem 42 does not generate unnecessary interference waves. The multiplexing HE device for ADSL 44 converts the demodulated downlink data signal into a second downlink data signal. The second downlink data signal does not overlap with a telephone voice signal (the highest frequency is 3.4 kHz) by a telephone line to be described later, and a frequency band above the frequency, for example, 138 kHz to 110.
3 kHz is selected. This second downlink data signal has a transmission rate of, for example, 1.5 Mbps or more, and
It is supplied to the SL splitter 46. This splitter 4
Reference numeral 6 is also connected to a public telephone line, and superimposes a telephone (receiving) voice signal and a second downlink data signal.

A data signal transmission line, for example, a telephone line 48 is individually laid from the splitter 46 to each room as shown in FIG. Modular 5 at the end of each telephone line 48
0 are connected, and these modular units 50 are connected to an Internet terminal device 52. The Internet terminal device 52 has an ADSL splitter 54. The splitter 54 separates the telephone voice signal transmitted through the telephone line 48 from the second downstream data signal, outputs the telephone voice signal to the telephone 56, and outputs the second downstream data signal to the modem 58.
To supply. The modem 58 demodulates the second downlink data signal and supplies it to an information terminal device, for example, a personal computer 60.

On the other hand, the upstream data signal of the Internet from the personal computer is converted into a first upstream data signal of a frequency which can be transmitted through the telephone line 48 and does not overlap with the second downstream data signal or the telephone voice signal, for example, 25 kHz to 138 kHz. , Modulated by the modem 58. This first
The upstream data signal has a transmission rate of, for example, 500 to 864 kbps, and is transmitted by the splitter 54 via telephone (transmission).
The signal is superimposed on the audio signal and supplied to the splitter 46 of the premises headend 16 via the modular 50 and the telephone line 48. The splitter 46 separates the superimposed telephone (transmission) audio signal from the first uplink data signal, and transmits the telephone (transmission) audio signal to a public telephone line. On the other hand, the first uplink data signal is supplied to the multiplex HE device 44, where it is demodulated into an uplink signal and output to the modem 42.

The modem 42 converts the demodulated upstream data signal into a second upstream data signal. As shown in FIG. 3A, the second uplink data signal includes the downlink signal and the first uplink data signal.
Non-overlapping frequency band with downlink data signal, for example, 10 MHz
z to 50 MHz. This second uplink data signal is
After passing through an up-filter 62 whose pass band is selected so as to pass only the second up-data signal, and amplified by an amplifier 64, the head passes through a mixing / demultiplexer 32, an input / output terminal 30, and a main transmission line 10. Output to end 2. Only the second uplink data signal extracted by the uplink filter 62 is
Since the signal is transmitted to the main transmission line 10, even if an interference wave is generated in the modem 42, it is not transmitted to the main transmission line 10. In the headend 2, the second uplink data signal is demodulated into an uplink data signal and transmitted to the provider.

When a terminal side transmits an Internet data signal by superimposing a CATV signal on a CATV line like a CATV Internet, an upstream data signal is greatly affected by ingress noise. However, in this data transmission system, the upstream and downstream data signals are transmitted by the telephone lines 48 provided separately between the headend 16 in the building and each of the Internet terminal devices 52. The data signal is not affected by the ingress noise. Moreover, since the frequency bands of the first uplink data signal and the second downlink data signal are non-overlapping frequencies with the telephone voice signal, the existing telephone line 48 can be used as it is, and the multiplexed HE Device 4
1 and the splitter 46 and the modem 58 and the splitter 54 in the Internet terminal device 52 on the terminal side, the first uplink and the second downlink data signals can be transmitted.

Note that the transmission speed of the first uplink and second downlink data signals may be reduced if the transmission distance is long, but the transmission distance from the premises headend 16 to the Internet terminal device 52 is the maximum. However, since the distance is several tens of meters, the transmission speed hardly decreases.

The second upstream data signal and the first downstream data signal on the main transmission line 10 from the head end 16 to the head end 2 in the building may be affected by the ingress noise. The second upstream data signal output from the head end 16 is hardly affected by the ingress noise, but is affected by the ingress noise only in the main transmission line 10, and therefore has no significant effect.

In this data transmission system, it is only necessary to provide a server 28 at the head end 2, and it is not necessary to provide a server or a dedicated line for Internet connection such as ISDN at the head end 16 in the building.

In the above embodiment, the telephone line 48 is used as a transmission line for data signals of the Internet.
Alternatively, a dedicated data signal transmission line that is not shared with a telephone line may be provided. In the above-described embodiment, the premises headend 16 is used as a relay device, but this is for connecting to the Internet in a so-called ridge joint reception system. However, the present invention is not limited to the in-building shared reception system. For example, in a shared reception system in which terminals are provided for a plurality of single-family houses, a relay device can be provided for these.

[0025]

As described above, according to the present invention, an Internet data signal is transmitted from the server to the relay device using the main transmission line of the joint receiving facility, and the relay device to each terminal are individually transmitted. Since the data signal of the Internet is transmitted via the data signal transmission line provided in the server, the transmission of the Internet data signal to the server is hardly affected by the ingress noise.

[Brief description of the drawings]

FIG. 1 is a block diagram of a data transmission system according to the present invention.

FIG. 2 is a block diagram of an in-building headend used in the data transmission system of FIG. 1;

FIG. 3 is a frequency array diagram of each signal used in the data transmission system of FIG. 1;

[Explanation of symbols]

 2 Head end 10 Main transmission line 16 Head end in building (relay device) 20 Sub transmission line 60 Personal computer (information terminal equipment)

Continued on the front page F term (reference) 5C056 FA03 FA05 FA08 HA01 HA04 HA14 HA15 5C064 BA01 BB05 BC11 BC12 BC13 BC14 BC16 BD01 BD07 5K022 AA03 AA31 5K033 AA07 BA07 BA14 CA17 DA15 DB01 DB09 DB18 DB22

Claims (3)

[Claims] A head end for transmitting a first downlink data signal from the server to a main transmission line together with a television signal; and a head end connected to the main transmission line and connected to each terminal. The television signal is transmitted through a sub-transmission path, and the first downlink data signal is converted into a second downlink data signal that can be transmitted through a data signal transmission line provided individually for each terminal. The data signal transmission line to the information terminal device, the first terminal can transmit the first uplink data signal transmitted from the information terminal device via the data signal transmission line on the main transmission line. And a relay device that converts the data into an upstream data signal and outputs the data to the server via the main transmission path. 2. The data transmission system according to claim 1, wherein each of the data signal transmission lines is a telephone line that can be connected to a public telephone line, and the second downlink data signal and the first uplink data signal are A data transmission system that does not overlap with the frequency band of telephone voice signals on public telephone lines. 3. An input / output terminal to which a television signal and a first downlink data signal are input, and an output terminal connected to a sub-transmission line and outputting a television signal from the input / output terminal to the sub-transmission line. A downlink filter for extracting the first downlink data signal from a television signal from the input / output terminal and a first downlink data signal; and a first uplink from each information terminal device via a data signal transmission line. A data signal and a first downstream data signal of a downstream filter are input, the first upstream data signal is converted into a second upstream data signal that can be transmitted on the main transmission path, and the first downstream data signal is converted to the data signal transmission signal. Conversion means for converting the data into a second downlink data signal that can be transmitted on a line and outputting the converted data signal to the data signal transmission line; and a second uplink data signal from the conversion means. Passed through a signal, an uplink filter for outputting the input and output terminals, the data transmission system relay apparatus provided.