JP3722590B2 - CATV system, transmission apparatus, reception apparatus, and control signal transmission method used therefor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a data transmission / reception apparatus in a CATV (Community Anntena Television) system, and in particular, a terminal from a center to a reception terminal apparatus using a transmission line of a television signal (hereinafter referred to as a TV signal). The present invention relates to a data transmission / reception apparatus in a CATV system configured to transmit control data, program data, and the like.
[0002]
[Prior art]
Conventionally, a CATV system that distributes a TV program using a coaxial cable is known. As shown in FIG. 8, such a CATV system sends information such as TV signals from a center called a head end 61 for sending TV signals and the like to each home 63 to 65 via a coaxial cable called an access network 62. A signal is transmitted.
[0003]
FIG. 9 is a diagram schematically showing a method of transmitting an information signal from the head end.
[0004]
In the figure, in the conventional CATV system, as shown in the figure, the transmission frequency band of the TV signal is set to approximately 50 MHz to 450 MHz, and within this frequency band, the bandwidth of one channel is set to about 6 MHz. Channel TV signals are transmitted by frequency division multiplexing. In this case, as a TV signal to be transmitted, an audio signal is frequency-division-multiplexed on a baseband video signal of 0 to 5 MHz, and a carrier wave is modulated by this multiplexed signal. The TV signal of each channel has a different carrier frequency. It has.
[0005]
In the receiving terminal devices of the homes 63 to 65, the TV program of the desired channel can be selected and received by tuning the tuner to the carrier frequency of the desired channel.
[0006]
Note that in the conventional CATV system, simultaneously with the transmission of a TV signal, data (that is, a control signal) for controlling whether or not the receiving terminal apparatus can receive the TV signal may be transmitted. This is because, for example, in order to perform limited reception (only TV receivers who have contracted are allowed to view TV programs), the TV signal to be transmitted is encrypted, but this encryption code is decrypted. This is the transmission of key data. Although the transmission of the control signal is performed simultaneously with the transmission of the TV signal, as shown in FIG. 9, it is performed using a dedicated transmission band 72 having a frequency band different from the transmission band 71 of the TV signal. It is common.
[0007]
In addition, since a normal receiving terminal apparatus has only one tuner, in order to receive such a control signal, a dedicated transmission band 72 for this control signal is selected before starting reception of the TV signal. There must be. The receiving terminal device can decrypt the TV signal of the desired channel to be received based on the received control signal. In this way, the CATV system provides services such as providing TV programs only to contract subscribers.
[0008]
[Problems to be solved by the invention]
Recently, development of a digital CATV system for digitizing and transmitting a video signal has been promoted at a rapid pace against the background of progress in high-efficiency compression encoding technology for images and computer technology.
[0009]
When the CATV system is digitized in this way (that is, in the digital CATV system), for example, the receiving terminal device has the same architecture as a general-purpose computer so that it can be operated by a program, and this operation program is started. A configuration method in which data is sometimes transmitted from the head end to the receiving terminal device is also possible. In this case, the receiving terminal device only needs to store a program for receiving data such as an operation program from the head end, and the capacity of the memory, magnetic recording device, etc. can be reduced. . A method of acquiring such program data when necessary is called a data download method.
[0010]
This data download method is an excellent method that can improve the operation of the receiving terminal device by updating the data content on the headend side, but it should be downloaded. When the amount of information increases, there is a problem that loading takes time.
[0011]
Also, when the amount of control data (download data) to be downloaded such as an operation program of the receiving terminal device is large, it becomes impossible to transmit the control signal of the control data through the video channel, and the transmission channel dedicated to the control signal Is required. For this reason, in order to watch a TV program of a desired channel, not only the channel selection but also the channel selection operation to the dedicated transmission channel in order to receive the control signal before that. Is required. It is essential to receive this download data and to update the old control data to a new one, but the operation program of the receiving terminal device is not changed so frequently, and therefore the operation program is not changed. However, performing a channel selection operation of the control signal to the dedicated transmission channel every time a TV program reception starts increases a very wasteful operation.
[0012]
Furthermore, since the conventional CATV system has only one dedicated transmission channel for control signals, there is a problem that the system becomes inoperable when a failure occurs in the line of this system.
[0013]
  The first object of the present invention is to solve such a problem, enable control data to be downloaded efficiently and in a short time, and to effectively use the Dern load method.CATV system, transmission apparatus, reception apparatus, and control signal transmission method used thereforIs to provide.
[0014]
  Another object of the present invention is to prevent the transmission / reception of information signals from being hindered even when a failure occurs in the transmission channel of the control signal.CATV system, transmission apparatus, reception apparatus, and control signal transmission method used thereforIs to provide.
[0015]
[Means for Solving the Problems]
  In order to achieve the first object, the present invention provides:A head end for transmitting a plurality of television signals and the like and one or more receiving terminal devices are connected via a signal transmission path, and a television signal of a plurality of video channels is transmitted from the head end via the signal transmission path. A CATV system that transmits to a receiving terminal device side, and the one or more receiving terminal devices select and receive one of the television signals of the plurality of video channels, wherein the head end includes a program data download A control signal generating means for repeatedly generating a control signal; a common control signal generating means for repeatedly generating a common control signal common to the video channel for instructing download of the download control signal; and a plurality of television signals multiplexed. Each is a television signal of a separate video channel, and further multiplexed television signals. A plurality of multiplexing means for multiplexing the common control signal every time, a plurality of first modulation means for modulating each of the frequency multiplexed signals from each of the multiplexing means, and the download control signal for the first control means Second modulation means for modulating in the same modulation system as the modulation means, and frequency multiplexing means for frequency-multiplexing the modulation signals from the first and second modulation means at different carrier frequencies, The receiving terminal device transmits the television signal, the common control signal transmitted together with the television signal through the plurality of video channels, and a channel of a system different from the plurality of video channels. A tuner for receiving the download control signal, a demodulating means for demodulating the received signal selected by the tuner, and the television signal from the received signal demodulated by the demodulating means. Receiving the common control signal, determining whether to download the download control signal based on the common control signal, and controlling the download control signal to be downloadable when it is determined that the download is to be performed. Control means and storage means for storing the program data of the received download control signal are provided.
[0016]
  In order to achieve the first object, the present invention is a transmitting apparatus including a head end that transmits television signals of a plurality of video program channels to one or more receiving terminal apparatuses via a signal transmission path. A control signal generating means for repeatedly generating a download control signal including program data, and a common control signal generating means for repeatedly generating a common control signal common to video channels instructing the download of the download control signal. A plurality of television signals, each of which is converted into a television signal of a separate video channel, and a multiplexing means for multiplexing the common control signal for each multiplexed television signal; and the multiplexing means A plurality of first modulation means for modulating each of the frequency multiplexed signals from each of the first and second download control signals; Second modulation means for modulating in the same modulation system as the modulation means, and frequency multiplexing means for frequency-multiplexing the modulated signals from the first and second modulation means at different carrier frequencies It is.
[0017]
  In order to achieve the other object, the transmission apparatus according to the present invention described above includes a delay unit that delays the download control signal, and a delay signal from the delay unit as the first and second modulation units. Third download means for modulating with the same modulation method is provided, and when the download control signal is transmitted through a plurality of channels and the repetition period of the download control signal is Tc, the delay means downloads the plurality of channels. The control signals are transmitted with a timing shift of Tc / N unit.
[0018]
  In order to achieve the first object, the present invention provides a download control signal including downloadable program data transmitted from a head end via a signal transmission path, and downloading the program data of the download control signal. A receiving apparatus that selects and receives any one of a common control signal for instructing and a plurality of television signals transmitted together with the common control signal via a plurality of video channels, And a tuner for receiving the common control signal transmitted via a plurality of video channels together with the television signal and a download control signal transmitted via a channel of a system different from the common control signal; Demodulating means for demodulating the received signal selected by the tuner, and receiving signal demodulated by the demodulating means Decoding means for decoding a revision signal; receiving the common control signal; determining whether to download the program data of the download control signal with the common control signal; A control means for controlling the signal so as to be downloadable, and a storage means for storing the program data of the received download control signal, and one of the common control signals sent via the plurality of video channels. Thus, the download control signal is selected and the program data of the download control signal is downloaded.
[0019]
  In order to achieve the first object, according to the present invention, a head end for transmitting a plurality of television signals and the like and one or more receiving terminal devices are connected via a signal transmission path, and a plurality of signals are transmitted from the head end. A television signal of a video channel is transmitted to the receiving terminal device side through the signal transmission path, and the one or more receiving terminal devices select and receive one of the television signals of the plurality of video channels. In a control signal transmission method in a CATV system, a first step of repeatedly generating a download control signal including program data, a second step of modulating the download control signal, and downloading of the program data of the download control signal A third step of repeatedly generating a common control signal common to the video channel for instructing the video channel; A fourth step of frequency-multiplexing the signal into each television signal of the plurality of video channels, and modulating the frequency-multiplexed signal with the same modulation scheme as the modulation scheme of the download control signal in the second step The fifth step includes a sixth step in which the download control signal and the common control signal are frequency-multiplexed at different carrier frequencies and transmitted to the receiving terminal device side.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, embodiments of the present invention will be described with reference to the drawings.
  FIG. 1 shows a CATV system according to the present invention.Data transmission apparatus and data transmission method1 is a block diagram showing a head end in the first embodiment, wherein 1 is a common control signal generator, 2 to 7 are video signal sources, 8 is a control signal generator, 9 to 11 are multiplexers, and 12. ˜15 is a QAM modulation circuit, and 16 is a frequency multiplexing device.
[0021]
In the figure, the head end includes video signal sources 2 to 7, common control signal generator 1, control signal generator 8, multiplexers 9 to 11, QAM (Quadrature Amplitude Modulation) modulators 12 to 15, frequency multiplexing. And the like. The video signal sources 2 to 7 are devices for generating a TV signal in which an audio signal is added to a video signal of a TV program, and are composed of, for example, a real-time MPEG2 encoder or a video server. A TV signal that has been data-compressed by an encoding apparatus such as MPEG2 can transmit a plurality of programs through a conventional analog one-line channel. Therefore, the compression-coded TV signals from the video signal sources 2 and 3 are multiplexed by the multiplexing device 9, and similarly, the compression-coded TV signals from the video signal sources 4 and 5 are multiplexed. Thus, the compression-coded TV signals from the video signal sources 6 and 7 are multiplexed by the multiplexer 11 respectively. The multiplexed signals output from the multiplexers 9, 10, and 11 are QAM modulated by the QAM modulation circuits 12, 13, and 14, respectively, into signals in a format suitable for signal transmission on an analog CATV line, and different carrier frequencies. And then multiplexed as separate TV channels by the frequency multiplexing device 16 and output as a CATV headend transmission signal.
[0022]
On the other hand, a control signal to be transmitted to a receiving terminal device described later is a common control signal CL.₁And other control signals CL₂And the common control signal CL₁From the common control signal generator 1 and the control signal CL₂Are repeatedly generated from the control signal generator 8 respectively. Here, the common control signal CL₁Is suppressed to an amount of information that can be multiplexed with a TV signal and transmitted, and is supplied to the multiplexers 9, 10, and 11 and multiplexed with the TV signal. As a result, even if the receiving terminal apparatus receives the TV signal of any TV channel, at the same time, the common control signal CL is transmitted through the receiving channel.₁Is also received. Further, the control signal CL₂Is subjected to QAM modulation by the QAM modulation circuit 15, further becomes a carrier frequency that becomes a channel (control channel) different from the TV channel, is supplied to the frequency multiplexing device 16, and is frequency-multiplexed with the TV channel.
[0023]
In this manner, the output signals of the QAM modulation circuits 12 to 15 are output from the frequency multiplexing device 16 as signals of separate channels and transmitted to the receiving terminal device via an analog CATV line (not shown).
[0024]
Here, the number of video signal sources is six and the number of TV signals multiplexed by each of the multiplexers 9 to 11 is two, but the present invention is not limited to this.
[0025]
By the way, in a digital CATV system that has been practically used so far to transmit a TV signal compressed and encoded based on MPEG2, an image is compressed and encoded to about 7 Mbit / second based on MPEG2. In general, four channels of the compressed and encoded TV signals (MPEGTV signals) are multiplexed to form one channel. In this case, the transmission rate is 7 × 4 = 28 Mbit / sec. On the other hand, as described with reference to FIG. 9, when such a digital signal is transmitted with a bandwidth of 6 MHz equivalent to the conventional analog TV signal, the maximum transmission rate of the digital signal in this case can be up to approximately 29 Mbit / sec. is there. Therefore, as described above, when four MPEGTV signals are multiplexed and transmitted with a bandwidth of 6 MHz, a margin of about 1 Mbit / sec is obtained in the transmission rate, and therefore, common control is performed for this about 1 Mbit / sec. Signal CL₁ Can be assigned.
[0026]
For this reason, in this embodiment, the common control signal CL₁The amount of information is limited so that the transmission rate is about 1 MHz. FIG. 2 shows such a common control signal CL.₁In this specific example, the address information of the receiving terminal device of about 4 bytes and data for instructing to update the operation program related to the receiving terminal device (that is, the updater index) For example, a total of 8 bytes (= 64 bits) with a flag field of about 4 bytes.
[0027]
Therefore, now assuming that the number of subscribers of this CATV system is 50,000 households, the common control signal CL₁As 5 × 10^FourType required, but common control signal CL for all these subscribers₁The total amount of information is 8x5x10^Four= 4 × 10^FiveSince this is a byte (= 3.2 Mbit), the time required for transmission at a line speed of 1 Mbit / sec is about 3 seconds. Therefore, the common control signal CL for all the subscribers₁Can be repeatedly transmitted in a cycle of about 3 seconds. For this reason, each receiving terminal device can determine the presence or absence of update data within about 3 seconds.
[0028]
In FIG. 1, since two TV signals are multiplexed into one TV channel, the common control signal CL₁Can be sufficiently transmitted at a transmission rate of 1 Mbit / sec. In general, when M TV signals are multiplexed to form one TV channel, a common control signal CL is added to this.₁ It goes without saying that the bandwidth of this 1 TV channel is set to such an extent that can be multiplexed and transmitted.
[0029]
Control signal CL transmitted on a control channel which is a channel different from the TV signal₂Is information to be downloaded such as an operation program of the receiving terminal device, and an instruction as to whether or not to download this information is common control signal CL for each receiving terminal device.₁Made by.
[0030]
FIG. 3 is a block diagram showing a receiving terminal device for the headend shown in FIG. 1, wherein 17 is this receiving terminal device (also called a set top box), 18 is a tuner, 19 is a QAM demodulating circuit, and 20 is system decoding. A circuit, 21 is a video decoding circuit, 22 is an audio decoding circuit, 23 is a CPU (central processing unit), and 24 is a memory.
[0031]
In the figure, the receiving terminal device 17 includes a tuner 18, a QAM demodulating circuit 19, a system decoding circuit 20, a video decoding circuit 21, an audio decoding circuit 22, a CPU 23, a memory 24, and the like. In such a configuration, the signal received by the tuner 18 is decoded into a digital signal by the QAM demodulating circuit 19, and then the video signal and audio signal of the TV signal desired to be received by the system decoding circuit 20, and the common control signal CL.₁ And are supplied to a video decoding circuit 21, an audio decoding circuit 22, and a CPU 23, respectively.
[0032]
Here, the video signal and the audio signal are compression-encoded by the MPEG system, and the video signal, the audio signal, and the common control signal CL₁Are configured in accordance with the MPEG system multiplexing standard (H.222.0 or ISO / ITE13818-1), the system decoding circuit 20 is H. An operation of decoding a data stream in accordance with the 222.0 standard is executed. According to this configuration, while receiving the video signal and the audio signal, at the same time, the common control signal CL₁Can also be received.
[0033]
The CPU 23 receives the received common control signal CL for designating its own terminal address.₁The common control signal CL₁The presence or absence of an updater index for instructing the change of the operation program in the flag field is determined. If there is this updater index, the CPU 23 generates a system control signal, which causes the tuner 18 to control the control signal CL.₂The control channel is controlled to be selected. In this way, the control signal CL₂Is received, this control signal CL₂Are processed by the QAM demodulating circuit 19 and the system decoding circuit 20 and then fetched by the CPU 23, and the operation program is extracted and stored in the memory 24. When the download of the operation program is completed, the CPU 23 then tunes the tuner 18 to the TV channel designated by the viewer by the system control signal, and uses this operation program stored in the memory 54 to tune this TV. Perform channel reception control.
[0034]
As the memory 24, a semiconductor memory may be used, but other storage devices such as a magnetic storage device using a magnetic desk as a medium may be used.
[0035]
FIG. 4 is a flowchart showing the receiving operation of the receiving terminal device 17, and FIG. 4 will be described below.
[0036]
In the figure, when the receiving terminal device 17 starts operating, first, the tuner 18 is tuned to the TV channel desired to be received (step 100), and this TV channel is received. At this time, the common control signal CL is used for this TV channel.₁Is multiplexed with the TV signal and transmitted, so this common control signal CL₁Is received (step 101). The CPU 23 sends this common control signal CL₁And the presence or absence of an updater index (FIG. 2) for instructing update of the operation program is determined (step 102).
[0037]
If there is an update index, the receiving terminal device 17 needs to update the operation program, so the control signal CL₂The tuner 18 is tuned to the control channel (step 103), and the control signal CL₂And a new operation program is stored in the memory 24 (step 104). Then, the tuner 18 is tuned to the TV channel desired to be received, and the operation proceeds to the TV signal receiving operation (step 105). In step 102, the common control signal CL₁When it is determined that there is no updater index, the control signal CL₂ The reception operation of the desired TV signal is continued as it is without performing the reception operation (steps 103 and 104) (step 105).
[0038]
In this way, when there is no need to update the operation program, the TV program receiving operation can be started immediately and the viewer is not kept waiting.
[0039]
When the TV channel is continuously received, the series of operations of steps 101 to 107 are repeated, so that the common control signal CL is received even during reception of the TV channel.₁ If there is a need to change the operation program, the operations of steps 103 and 104 are performed.
[0040]
If the received TV program is changed at the request of the viewer during reception (step 106), the tuner 18 is tuned to the TV channel to which the program is transmitted (step 100). The above-described series of operations are repeatedly executed.
[0041]
As described above, the download data and the update index instructing the necessity of the download are divided, and the latter has an information amount of only about 8 bytes. In general, the receiving terminal device 17 only needs to determine the necessity of downloading the control data (ie, the necessity of changing the operation program), and only when there is such a necessity, downloading is possible. Should be done. Therefore, even if the amount of control data to be downloaded becomes large, the CPU 23 reduces the normal processing load of the control signal from the head end, and shortens the time required to determine whether or not the download is necessary. Thus, the TV program of the desired channel can be received immediately.
[0042]
In addition, since the update index is repeatedly transmitted periodically and is received on the same channel as the received TV program, the updater index is received even during reception, and the necessity for downloading is required. If this occurs, the operation program is downloaded immediately and the operation program is downloaded. Therefore, any time there is a request to change the operation program, an obstacle to reception of the TV program is immediately responded to this request. It can be pressed to the minimum.
[0043]
  FIG. 5 shows a CATV system according to the present invention.Data transmission apparatus and data transmission methodFIG. 15 is a block diagram showing a head end in the second embodiment, in which 15a and 15b are QAM modulation circuits, 25 is a delay circuit, and portions corresponding to those in FIG. Omitted.
[0044]
In the second embodiment, the control signal CL₂Two transmission channels are provided, each with the same control signal CL₂Is transmitted.
[0045]
That is, in FIG. 5, the control signal CL generated by the control signal generator 8₂On the other hand, similarly to the first embodiment shown in FIG. 1, the QAM modulation circuit 15a performs QAM modulation and a control signal CL having a predetermined carrier frequency._2aAnd is supplied to the frequency multiplexing device 16, and further, this control signal CL₂Is delayed by the delay circuit 25, then QAM modulated by the QAM modulation circuit 15b, and a control signal CL having a predetermined carrier frequency._2bAnd supplied to the frequency multiplexer 16.
[0046]
FIG. 6 is a diagram showing a transmission method in the second embodiment.
In the figure, an analog signal transmission band 26 for transmitting a predetermined analog signal is set on the low frequency side, and the output signals of the QAM modulation circuits 12 to 14 in FIG. 5 are transmitted to the high frequency side. A digital signal transmission band 27 is set for this purpose. Then, between these analog signal transmission band 26 and digital signal transmission band 27, the control signal CL from the QAM modulation circuit 15a._2aA control channel 28 is set for transmitting. The transmission band allocation so far is the same as that of the first embodiment shown in FIG. In the second embodiment, the control signal CL from the QAM modulation circuit 15b is further provided on the high frequency side of the digital signal transmission band 27._2bA control channel 29 is set for transmitting.
[0047]
Here, the control signal CL₂However, assuming that the signal period is Tc, the signal is repeatedly generated and transmitted with a period of approximately Tc.₂Is transmitted through the control channels 28 and 29 of the two systems.₂Is delayed by 1/2 of the repetition period Tc.
[0048]
FIG. 8 shows these two control signals CL._2a, CL_2bIt is a figure which shows the timing relationship and data structure of this.
[0049]
In the figure, as described above, the control signal CL_2a, CL_2bThe time lag between and is Tc / 2.
[0050]
Further, the control signal CL₂(Therefore, the control signal CL_2a, CL_2b) Includes a control signal unit 31 and a header 30 provided at the head thereof, and the stream of the control unit 31 is divided into a plurality of packets 32. This header 30 is composed of a start mark indicating the head of the control unit 31 and data of the number of packets 32 constituting the control unit 31. The packet 32 is composed of a sequence number 33 representing the order in the control unit and a data payload 34 including any download data in the operation program.
[0051]
The control signal CL in the first embodiment shown in FIG.₂Has a data structure similar to this.
[0052]
Also in the second embodiment, the receiving terminal device has the circuit configuration shown in FIG. In the receiving terminal device 17, the control signal CL₁Indicates that the operation program needs to be changed, the tuner 18 is first set to tune to the control signal transmission band 28 (FIG. 6), for example, thereby controlling the control signal CL._2aHowever, the reception start time is arbitrary, and the control signal CL_2aIt is common to start reception from the middle of the.
[0053]
Therefore, the CPU 23 detects the sequence number 33 of the first packet 32 after the start of reception, and from the detected sequence number 33, the first packet 32 is the first half part of the control unit 31 or the second half part. If it is in the first half, the tuning frequency of the tuner 18 is changed and the control signal CL is changed._2bIf it is the latter half, the control signal CL is received as it is._2aIs kept in the receiving state. When the header 30 of the next control unit 31 is detected, data such as an operation program included in the data payload 34 from the first packet 32 of the control unit 31 is stored in the memory 24 and downloaded.
[0054]
Control signal CL₂If the control unit 31 is not received from the head, the download data cannot be downloaded completely. However, as described above, the first received packet 32 after the start of reception is in the first half of the control unit 31. Sometimes, the tuning frequency of the tuner 18 is switched to control the other control signal CL.₂If the control signal CL is received in the latter half, the control signal CL is held as it is.₂ It is possible to minimize the time required to start downloading after the start of reception.
[0055]
The control signal CL₂In order to determine in which order the control unit 31 has the first packet 32 after the start of reception, the total number of packets constituting the control unit 31 is required. Here, the total number of packets is It is assumed that the data is fixed and data representing it is held in the CPU 23. When the number of packets 32 constituting the control unit 31 differs according to the amount of download data, the control signal CL₁Control signal CL at that time₂Also, information indicating the number of packets may be included, and the CPU 23 may use this.
[0056]
In the second embodiment, the control signal CL₂Since there are two control channels for transmitting the signal, even if a fault occurs on one side, the control signal CL on the other side₂Transmission can be continued, and the fault response capability of the CATV system can be improved.
[0057]
By the way, in the second embodiment, the control signal CL₂Although two control channels are provided, the present invention is not limited to this. In general, the control signal CL₂N (where N is an integer of 2 or more) system control channels can be provided. In this case, the control signal CL₂If the repetition period is Tc, the control signal CL of each system₂A timing shift of Tc / N is provided between them. As the CPU 23, a control signal CL of a specific control channel₂The order of the first received packet after the start of reception at the control unit is detected, and from this detection result, the control signal CL of which control channel of the N channels₂Is received, it is determined whether the download can be started earliest, the tuning frequency of the tuner 18 is set, and the control channel is received. In this way, the control signal CL₂After the start of reception, download can be started quickly.
As described above, in the present invention, the first control signal for notifying whether or not the program data needs to be updated is communicated to the receiving terminal device on all the video channels, and this program data is referred to as the video channel. Since it is sent by the second control signal of another channel, the receiving terminal device can determine whether or not it is necessary to update the program data even during reception of a normal TV program. Only when there is a channel, it is possible to select another channel and download the program data, respond immediately to the download instruction, and receive TV programs when there is no need for updating. It can be continued as it is, there is no such interruption of reception, and the channel selection of the above channels is meaningless as in the prior art. It can be avoided.
[0058]
【The invention's effect】
As explained above, according to the present invention,Since the first control signal indicates the necessity of downloading to the receiving terminal device, the amount of information is sufficiently small, and as the processing of a normal control signal in the receiving terminal device, the amount of information is Processing of a small first control signal is sufficient, and the processing load is greatly reduced.
[0059]
Moreover, according to the present invention,Since the second control signal is transmitted through a plurality of channels, even if a failure occurs in any of the channels, the download is surely performed, and the second control signal is transmitted through these channels. Since these control signals are transmitted at different timings, by appropriately selecting these channels, the time from when the download instruction by the first control signal is issued until the download is started is determined. It can be shortened.
[0060]
Furthermore, in the present inventionTherefore, according to a system configured to transmit update information, for example, terminal program information and information for instructing update of the information, for example, an update index, on a separate channel, a highly reliable CATV system is constructed. It is possible. In addition, it is possible to construct so that the CATV video channel band is not affected by the index.
In addition, a data transmission device applied to such a system can efficiently transmit update information, or a reception device can efficiently perform the download, and both the above information can be transmitted on different channels. Therefore, for example, even if a failure occurs on one side, an effective CATV channel can be transmitted and received without causing any trouble on the other side.
[Brief description of the drawings]
FIG. 1 shows data in a CATV system according to the present invention.Transmitting apparatus and data transmitting methodIt is a block diagram which shows the head end in 1st Embodiment of this.
FIG. 2 is a diagram showing a data configuration of a specific example of a common control signal in FIG. 1;
FIG. 3 is a block diagram showing a receiving terminal device for the head end shown in FIG. 1;
FIG. 4 is an operation flowchart showing a flow of control signal reception according to the embodiment of the present invention.
FIG. 5 shows data in the CATV system according to the present invention.Transmitting apparatus and data transmitting methodIt is a block diagram which shows the head end in 2nd Embodiment of this.
FIG. 6 is a diagram illustrating a signal transmission method according to the second embodiment illustrated in FIG. 5;
7 is a diagram showing a timing relationship of control signals of each channel and a data configuration thereof in the second embodiment shown in FIG.
FIG. 8 is a diagram showing a schematic configuration of a CATV system.
FIG. 9 is a diagram schematically illustrating an information signal transmission method in a conventional CATV system.
[Explanation of symbols]
1 Common control signal generator
2-7 Video signal source
8 Control signal generator
9-11 Multiplexer
12-15, 15a, 15b QAM modulation circuit
16 Frequency multiplexer
17 Receiving terminal device
18 Tuner
19 QAM demodulation circuit
20 System decoding circuit
21 Video decoding circuit
22 Speech decoding circuit
23 CPU
24 memory
25 Delay circuit
26 Analog signal transmission bandwidth
27 Digital signal transmission bandwidth
28, 29 Control channel
30 header
31 Control signal stream
32 packets
33 Sequence number
34 Data payload

Claims (5)

A head end for transmitting a plurality of television signals and the like and one or more receiving terminal devices are connected via a signal transmission path, and a television signal of a plurality of video channels is transmitted from the head end via the signal transmission path. In the CATV system that transmits to the receiving terminal device side and the one or more receiving terminal devices select and receive one of the television signals of the plurality of video channels,
The headend is
Control signal generating means for repeatedly generating a download control signal including program data;
Common control signal generating means for repeatedly generating a common control signal common to the video channel instructing to download the download control signal;
A plurality of multiplexing means for multiplexing a plurality of television signals, each of which is a television signal of a video channel, and further multiplexing the common control signal for each multiplexed television signal;
A plurality of first modulation means for modulating each of the frequency multiplexed signals from each of the multiplexing means;
Second modulation means for modulating the download control signal in the same modulation scheme as the first modulation means;
Frequency multiplexing means for frequency-multiplexing modulated signals from the first and second modulation means at carrier frequencies having different frequencies from each other;
With
The receiving terminal device
The television signal, the common control signal sent together with the television signal via the plurality of video channels, and the download control sent via a channel different from the plurality of video channels A tuner for receiving signals;
Demodulation means for demodulating the received signal selected by the tuner;
Decoding means for decoding the television signal from the reception signal demodulated by the demodulation means;
Control means for receiving the common control signal, determining whether to download the download control signal with the common control signal, and controlling the download control signal to be downloadable when it is determined to download;
Storage means for storing the program data of the received download control signal;
CATV system comprising the. In a transmission device including a head end that transmits television signals of a plurality of video program channels to one or more reception terminal devices via a signal transmission path,
  The headend is
    Control signal generating means for repeatedly generating a download control signal including program data;
    Common control signal generating means for repeatedly generating a common control signal common to video channels instructing to download the download control signal;
    Multiplexing means for multiplexing a plurality of television signals to make each one a television signal of a video channel, and further multiplexing the common control signal for each multiplexed television signal;
    A plurality of first modulation means for modulating each of the frequency multiplexed signals from each of the multiplexing means;
    Second modulation means for modulating the download control signal in the same modulation scheme as the first modulation means;
    Frequency multiplexing means for frequency-multiplexing modulated signals from the first and second modulating means at carrier frequencies having different frequencies from each other;
  A transmission device comprising: In claim 2,
  Delay means for delaying the download control signal;
  A third signal for modulating the delayed signal from the delay means by the same modulation method as the first and second modulation means. Modulation means and
  Provided,
  When the download control signal is transmitted through a plurality of channels and the download control signal repeat cycle is Tc, the delay means causes a timing shift of Tc / N units between the download control signals of the plurality of channels. Transmitting device characterized by being sent out. A download control signal including downloadable program data transmitted from the head end via a signal transmission path, a common control signal instructing to download the program data of the download control signal, and a plurality of the control signals together with the common control signal In a receiving apparatus for selecting and receiving any one of a plurality of television signals sent via a video channel,
  The television signal, the common control signal transmitted through the plurality of video channels together with the television signal, and the download control signal transmitted through a channel different from the common control signal. A tuner to receive,
  Demodulation means for demodulating the received signal selected by the tuner;
  Decoding means for decoding the television signal from the reception signal demodulated by the demodulation means;
  Control means for receiving the common control signal, determining whether or not the program data of the download control signal should be downloaded by the common control signal, and controlling the download control signal to be downloadable when it is determined that the program data should be downloaded When,
  Storage means for storing the program data of the received download control signal;
  With
  The download control signal is selected by one of the common control signals sent via the plurality of video channels, and the program data of the download control signal is downloaded. Receiver device. A head end for transmitting a plurality of television signals and the like and one or more receiving terminal devices are connected via a signal transmission path, and television signals of a plurality of video channels are connected from the head end via the signal transmission path. In a control signal transmission method in a CATV system that is transmitted to a receiving terminal device side and the one or more receiving terminal devices select and receive any one of the television signals of the plurality of video channels.
  A first step of repeatedly generating a download control signal including program data;
  A second step of modulating the download control signal;
  A third step of repeatedly generating a common control signal common to the video channel instructing to download the program data of the download control signal;
  A fourth step of frequency multiplexing the common control signal to each television signal of the plurality of video channels;
  A fifth step of modulating the frequency multiplexed signal with the same modulation scheme as the modulation scheme of the download control signal in the second step;
  A sixth step of frequency-multiplexing the download control signal and the common control signal at carrier frequencies having different frequencies and transmitting the same to the receiving terminal device
  A control signal transmission method comprising:

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