JPH11308596A - Indoor image multiplex transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide many video services regardless of simple wiring form and to provide all broadcast services desired in all indoor rooms at a low cost by reducing the wiring cost and the terminal cost. SOLUTION: The system consists of a master device 1 and pluralities of terminals 2, which are wired according to the star topology using optical fibers for distribution of images. The system is provided with the master device 1 having pluralities of reception sections for a video signal each consisting of a tuner 5, an A/D converter 6, a demodulation circuit 7 and an error correction circuit 8 and having means 9, 12 that apply time base multiplexing to digital broadcast signals outputted from the reception sections and apply electrooptic conversion to the processed signals and with each terminal 2 that applies photoelectric conversion (13) to the signal distributed via the optical fiber 3, selects (16) a required digital broadcast signal from the signal that is time base multiplexed, decodes (18) video and audio signals from the broadcast signal and reproduces the video and audio signals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an indoor image multiplexing system capable of providing all broadcast services desired in all indoor rooms at low cost by providing a large number of video services in a simple wiring form. The present invention relates to an integrated transmission system.

[0002]

2. Description of the Related Art Conventionally, when digital broadcasting is used indoors, a receiver called a set-top box 23 as shown in FIG. 2 is required. Examples of magazines related to digital broadcasting systems such as tuners include, for example, “Electronics”, June 1997, Kazuhiko Hashimoto, “Special Feature: The True Meaning of TV becoming Digital-Focus: On CS Digital Broadcasting,” p2 -14. In FIG. 2, reference numeral 22 denotes a small antenna, which can be satisfactorily received by a 40 cm antenna by an error correction technique. 5 is a tuner. In digital satellite broadcasting,
Since video / audio of about 5 channels is time-division multiplexed on one frequency corresponding to one analog channel, the tuner 5 extracts the video / audio in synchronization with a desired station. Reference numeral 6 denotes an A / D converter, which converts an analog signal into a digital signal. Reference numeral 7 denotes a QPSK demodulator, which extracts a digital signal by demodulating four-phase phase modulation (QPSK) widely used in digital satellite broadcasting.

An error correction circuit 8 uses two types of error correction systems, convolutional coding and Reed-Solomon coding. Since a correct digital signal can be returned by this error correction, good reception is possible even with a 40 cm class antenna. Reference numeral 16 denotes a descrambler, which is a digital signal scrambled (disturbed) so that a broadcaster cannot view the broadcast.
This scramble is restored so that it can be viewed.
Reference numeral 17 denotes a packet separation circuit that separates a packet broadcast using a digital signal from other signals and extracts the packet. Reference numeral 18 denotes an MPEG decoder, which restores a compressed signal to return to a normal digital video signal. The video signal is compressed to about 5 Mbps by a compression method called MPEG-2 VIDEO, and the audio signal is
256k by a compression method called G-2 AUDIO
It is compressed at about bps. Both compressed signals are expanded and returned to normal signals. 19 is a video receiver.
The analog signal extracted by the tuner 5 is converted into a digital signal by the A / D converter 6, demodulated by the demodulation circuit 7, corrected by the error correction circuit 8, and descrambled by the descrambler 1.
After the decryption in step 6, the necessary digital broadcast signal is selected by the packet separation circuit 17, the video and audio are decoded by the decoder 18 from the selected digital broadcast signal, and the video and audio are reproduced by the receiver 19. Do.

As described above, in the case of a detached house, when newly using digital satellite broadcasting, an antenna 22 and a set-top box 23 corresponding to the digital satellite are prepared and set from the antenna 22 with a coaxial cable. It is necessary to wire to the top box 23. On the other hand, in the case of a multiple dwelling house, it is difficult to prepare antennas individually, and it is necessary to separate vertical and horizontal polarized waves for CS digital broadcasting.
A joint reception method using a block converter as shown in FIG. That is, in FIG. 5, the vertical polarization of 1293 MHz to 1533 MHz is changed to 1385 MHz.
z to 1625MHz frequency, and 1308MHz to 154
The 8 MHz horizontal polarization is converted to a frequency of 1655 MHz to 1895 MHz, respectively, and FM and V of 75 MHz to 770 MHz are converted.
The signals are output to the video receiver together with channels 1 to 15 of HF and UHF broadcast waves and BS broadcast waves of 1035 MHz to 1335 MHz.

[0005]

However, in the collective reception system in an apartment house, a plurality of CS digital broadcasts cannot be received by one coaxial cable because the frequency bands to be received overlap. Therefore, in order to provide a service corresponding to a plurality of CS digital satellites in an apartment house, it is necessary to additionally wire a coaxial cable for distributing images. FIG. 6 is a diagram illustrating a usage form of a broadcast service according to a conventional distribution method. Traditionally,
As shown in FIG. 6, a plurality of satellite broadcasting antennas are provided for each CS, and the satellite broadcasting antennas are distributed to each room of an apartment house or a detached house through a distributor and a coaxial cable, respectively. In each house or each room, a set-top box for each CS is provided. Was placed and connected to the receiver. However, the wiring space in the apartment house is not enough for many coaxial cables, including existing and new houses.
It was difficult to add coaxial cable wiring, and there was a limit in providing a fulfilling video service. When additional wiring is difficult, a method of limiting the number of digital broadcasting services to be received to one and multiplexing VHF, UHF, BS, and CS on an existing coaxial cable using a block converter is applied. However, as shown in FIG.
A band of about z is required, and wiring using an existing coaxial cable cannot be coped with, and wiring changes and equipment replacement occur. Furthermore, even if there is enough space for additional wiring, every time a new digital satellite broadcast is received, it is necessary to add all wiring and block converters in the apartment house, and each house has a separate terminal for receiving images. Since it must be installed, there is a problem in receiving many satellite digital broadcasts at low cost.

[0006] Even in a detached house, it is necessary to switch between vertical polarization and horizontal polarization in order to receive digital satellite broadcasts. Cannot receive broadcasts independently. In order to receive independent broadcasts in each room in a house, it is necessary to set up multiple coaxial cables, but in a single-family house with limited wiring space, the space for installing multiple coaxial cables is limited, There has been a problem that wiring for using many digital satellite broadcasting services in a plurality of rooms is physically impossible at facilities. In addition, digital broadcasting, which is different for multi-family homes and single-family homes, is expensive because separate set-top boxes are required for each type of digital broadcasting. In order to use many digital satellite broadcasting services, it is desirable to share terminals. ing. The object of the present invention, in view of such conventional problems, when the wiring space is small, or even when additional wiring is difficult, can eliminate the congestion of the indoor wiring, it is possible to distribute images individually, It is an object of the present invention to provide an indoor image multiplexing transmission system that can support various digital broadcasting services at low cost.

[0007]

In order to achieve the above object, in an indoor image multiplexing transmission system according to the present invention, a system configuration in which a main device and a plurality of terminal devices are wired in an optical fiber star topology to distribute an image. The main device is a tuner corresponding to digital broadcasting by a broadcasting satellite, a communication satellite and terrestrial broadcasting, a circuit for demodulating a signal selected by the tuner, and a circuit for correcting an error of the demodulated digital broadcasting signal. And a time-division multiplexing of the digital broadcast signals output from the plurality of receiving units in the main apparatus, and then performs an electro-optical conversion. The multiplexed signal is distributed to each terminal by wiring using an optical fiber and a branch module.
Each terminal performs optical / electrical conversion of the distributed signal, selects a required digital broadcast signal from the time-axis multiplexed signal, decodes the video and audio from the extracted digital broadcast signal, and receives the signal. It has an indoor image multiplexing transmission system configuration in which video and audio are played back by a device.

According to the present invention, in the case of a single-family house, multiplexing means and means for switching signals to be selected by each tuner in the main unit without providing all the channels which may receive the number of receiving units are provided. A system may be configured by including a control circuit having a function of selecting a signal to be performed and providing the terminal device with a control circuit of the selection function. Further, a configuration may be adopted in which a broadcast signal selected in the terminal device is taken out to the outside via a high-speed interface, and redistributed via another receiver or a network between rooms. This makes it possible to share a transmission path for distributing a plurality of image services and eliminate the need for wiring using a plurality of cables, thereby achieving a simple and economical network configuration. For this reason, even when the wiring space is small or when additional wiring using a coaxial cable is difficult, wiring is easy, and a system for distributing a plurality of image services without congesting indoor wiring can be constructed. In addition, by sharing the tuner, power supply, control circuit, etc. in the main unit within the main unit, the cost of equipment can be reduced as compared with the case where many set-top boxes are arranged, and the cost of each terminal can be reduced. Since the configuration can be simplified, an indoor image distribution system using a plurality of broadcast services can be economically constructed.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a model diagram of an image multiplexing transmission system in an apartment house showing a first embodiment of the present invention. The image multiplexing transmission system of the present embodiment includes a main unit 1
And a plurality of terminal devices 2 are wired in a star topology with optical fibers 3 to distribute images. The main unit 1 includes a number of receiving units 4 corresponding to the number of transponders of digital satellite broadcasting or digital terrestrial broadcasting to be received. The receiving unit 4 includes a tuner 5
A circuit 6 for A / D converting the signal selected by the tuner 5, a circuit 7 for demodulating the signal, a circuit 8 for correcting errors in the demodulated digital broadcast signal, and the like 8.
The receiving unit 4 receives all transponders that may be used and performs demodulation and error correction, respectively. The main device 1 includes a multiplexing device 9 for multiplexing the signals output from the receiving unit 4, a common circuit 10 such as a power supply, a control circuit 11, and the like.

The signals output from the plurality of receivers 4 are used to multiplex the service signals included in each transponder with the multiplexer 9.
, And electro-optical conversion is performed by the E / O converter 12. The multiplexed signal is distributed to each terminal 2 by wiring with the optical fiber 3 and the branch module 13. The branch module 13 is configured by a passive optical splitter that branches an optical signal to a plurality of ports corresponding to the number of units. If a single-stage optical splitter cannot branch out by the number of houses, a configuration using a plurality of splitters may be adopted. Each terminal 2 performs an optical / electrical conversion of the distributed signal by the O / E converter 14 and then separates the signal from the time axis multiplexed signal into a demultiplexing circuit 1.
5. After descrambling by the descrambler 16, the necessary digital broadcast signal is selected by the packet separating circuit 17. The decoder 18 extracts the digital broadcast signal from the extracted digital broadcast signal.
To decode the video and audio, and the receiver 19 reproduces the video and audio.

[0011] Further, since all the transponders which are considered to be used in the apartment house are multiplexed, the service can be distributed regardless of which channel is used. As a multiplexing method, for example, an existing TDM technique is used. Information bit rate per transponder from communication satellite and broadcasting satellite is about 40 Mb / s
And the transmission speed of transmission after multiplexing is 2.4 Gb.
Even in the case of about it / s, about 60 transponders can be distributed. In the case of CS digital broadcasting, about 20 transponders per satellite are used for digital broadcasting. By using this system,
A service is possible in correspondence with a plurality of digital satellite broadcasts. Even if the number of receivers to be installed in the main unit is kept to a minimum at the time of initial introduction of the system, if the corresponding channel is set in advance between the main unit and the terminal device,
By adding a receiving unit in the main device, it is possible to cope with a future system upgrade.

As described above, in the present embodiment, the receiving unit is disposed at one place in the main device 1 and a plurality of digital broadcasting services are handled by one terminal device, so that different digital broadcasting services are provided in each house. There is no need to prepare or change a set-top box compatible with.
In addition, since broadcast signals are collectively received at one place, multiplexed and distributed to each house by one optical fiber, the congestion of wiring and the rise in cost due to wiring with a coaxial cable are suppressed. be able to. In addition, when a satellite broadcasting service is newly expanded, it is only necessary to add a receiving unit to the main device 1 side, and a new coaxial cable is provided,
There is no need to update the wiring equipment, and the image service can be used in all the doors in the apartment house.

FIG. 3 is a model diagram of an image multiplexing transmission system in an apartment house showing a second embodiment of the present invention. In the present embodiment, in the case of a single-family house, instead of providing the number of receiving units for all the channels that may receive the signal, the main unit 1 and the means for switching the signal to be selected by each tuner 5 are multiplexed. A system can be configured by including the channel selection circuit 20 having a function of selecting a signal to be converted and the transmission circuit 21 having the selection function in the terminal device 2. In other words, the tuner 5 has a function of preparing not only the number of transponders but also the number of services expected to be used at the same time, and selecting a transponder to be received by a selection signal from the terminal device 2. A system that economically distributes images without multiplexing multiple coaxial cables in each room or preparing multiple set-top boxes by multiplexing and distributing to each room by adopting such a configuration. Can be built.

FIG. 4 is a model diagram of an image multiplexing transmission system of a terminal device showing a third embodiment of the present invention. In this embodiment, as shown in FIG. 4, a high-speed external interface circuit 22 is provided on the terminal device 2 side, and a broadcast signal selected in the high-speed terminal device 2 is taken out through the high-speed interface circuit 22 (see arrow). ). This allows
A satellite digital communication service using a PC (personal computer) or the like can be used in each house. If a general-purpose interface such as IEEE1394 is used as an interface, the service can be easily used in each house.

FIG. 7 is a diagram showing a use form of a broadcast service by the indoor image multiplex transmission system of the present invention. In the present invention, as shown in FIG. 7, a main device that multiplexes a plurality of broadcast signals and a plurality of terminal devices that perform video selection are provided.
A multiplexed signal is distributed by an optical fiber using a system configuration in which a star topology is formed by using an optical fiber between these. That is, as is apparent from comparison with the conventional FIG. 6, a plurality of satellite broadcasting antennas are provided for each CS. What is necessary is just to distribute to each house or each room with a book cable, and only one terminal device needs to be arranged in each house or each room. Therefore, for both single-family homes and apartments,
It is possible to suppress the wiring cost and the terminal cost, and to provide all the desired broadcasting services in all the rooms indoors at low cost.

[0016]

As described above, according to the present invention,
The system has a main unit that multiplexes a plurality of broadcast signals and a plurality of terminal devices that select images, and uses a system configuration in which a star topology with optical fibers is used to distribute the multiplexed signals over optical fibers. Even in the case of a single-family house or an apartment house, a plurality of services can be distributed by one optical fiber, so that the form of indoor wiring can be simplified and a wiring system that does not congest indoor wiring can be configured. In addition, by sharing the power supply and the control unit, it is possible to provide all broadcast services desired in all rooms indoors at a low cost, and without adding indoor wiring to new services in the future. There is a remarkable effect that it can respond to

[Brief description of the drawings]

FIG. 1 is a block diagram of an indoor image multiplex transmission system showing a first embodiment of the present invention.

FIG. 2 is a block diagram showing a conventional indoor image multiplexing transmission system.

FIG. 3 is a block diagram of an indoor image multiplex transmission system showing a second embodiment of the present invention.

FIG. 4 is a block diagram of a terminal device having a high-speed interface according to a third embodiment of the present invention.

FIG. 5 is an explanatory diagram of a distribution method using a conventional block converter.

FIG. 6 is a diagram showing a usage form of a broadcast service according to a conventional distribution method.

FIG. 7 is a diagram illustrating a use form of a broadcast service by the indoor image multiplex transmission system of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Main apparatus, 2 ... Terminal apparatus, 3 ... Optical fiber, 4 ... Receiving part, 5 ... Tuner, 6 ... A / D conversion circuit, 7 ... Demodulation circuit, 8 ... Error correction circuit etc., 9 ... Multiplexing apparatus, 10: common circuit such as power supply, 11: control circuit, 12: E / O converter,
13 branch module, 14 O / E converter, 15 separation circuit, 16 descrambler, 17 packet separation circuit, 18 decoder, 19 receiver, 20 channel selection circuit, 21 transmission circuit, 22 ... Small antenna, 23
… Set top box.

Claims (3)

[Claims] 1. An indoor image multiplexing transmission system that distributes an image by wiring a main device and a plurality of terminal devices in a star topology using an optical fiber, and supports digital broadcasting by a broadcasting satellite, a communication satellite, and terrestrial broadcasting. Tuners, a demodulation circuit for demodulating a signal selected by the tuner, and a plurality of video signal receiving units each including an error correction circuit for correcting an error of the demodulated digital broadcast signal; and a digital signal output from the receiving unit. A main device including means for performing electric-optical conversion after time-division multiplexing of a broadcast signal; an optical fiber for distributing the multiplexed optical signal to a plurality of terminals; a branch module for branching to a plurality of terminals; After photoelectrically converting the signal distributed via the fiber, a required digital broadcast signal is selected from the time axis multiplexed signal, and Performs decoding of video and audio, an indoor image multiplex transmission system characterized by having a plurality of terminal apparatus for reproducing video and audio. 2. A channel selection circuit for switching a signal selected by each tuner in the main device, and a control circuit for selecting a signal to be multiplexed, and a selection signal of the channel selection circuit in the terminal device. 2. The indoor image multiplexing transmission system according to claim 1, further comprising a selection signal transmission circuit that transmits the signal. 3. The indoor image multiplexing transmission system according to claim 1, further comprising a high-speed external interface circuit for extracting a selected broadcast signal to the outside through a high-speed interface in the terminal device.