CA2029649C - Data transmission system for catv system - Google Patents
Data transmission system for catv systemInfo
- Publication number
- CA2029649C CA2029649C CA002029649A CA2029649A CA2029649C CA 2029649 C CA2029649 C CA 2029649C CA 002029649 A CA002029649 A CA 002029649A CA 2029649 A CA2029649 A CA 2029649A CA 2029649 C CA2029649 C CA 2029649C
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- information block
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- 230000005540 biological transmission Effects 0.000 title claims abstract description 52
- 239000000872 buffer Substances 0.000 claims description 25
- 238000000034 method Methods 0.000 claims description 4
- 230000004044 response Effects 0.000 claims description 3
- 238000010276 construction Methods 0.000 description 8
- 238000010586 diagram Methods 0.000 description 4
- 241000907506 Israel turkey meningoencephalomyelitis virus Species 0.000 description 3
- 230000009471 action Effects 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N7/00—Television systems
- H04N7/025—Systems for the transmission of digital non-picture data, e.g. of text during the active part of a television frame
- H04N7/03—Subscription systems therefor
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N7/00—Television systems
- H04N7/025—Systems for the transmission of digital non-picture data, e.g. of text during the active part of a television frame
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N7/00—Television systems
- H04N7/10—Adaptations for transmission by electrical cable
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- Engineering & Computer Science (AREA)
- Multimedia (AREA)
- Signal Processing (AREA)
- Two-Way Televisions, Distribution Of Moving Picture Or The Like (AREA)
- Television Systems (AREA)
- Communication Control (AREA)
- Details Of Television Systems (AREA)
Abstract
A data transmission system for sending a plurality of signals from a sender to at least one receiving terminal.
The sender comprises a memory for storing the plurality of signals, and a controller for causing the stored plurality of signals to be sent in a predetermined order, and for changing the predetermined order when the updating of a signal takes place, so that an updated signal is sent with priority to the receiving terminals.
The sender comprises a memory for storing the plurality of signals, and a controller for causing the stored plurality of signals to be sent in a predetermined order, and for changing the predetermined order when the updating of a signal takes place, so that an updated signal is sent with priority to the receiving terminals.
Description
-20296~9 DATA TRANSMISSION SYSTEM FOR CATV SYSTEMS
BACKGROUND OF THE INVENTION:
1. Field of the Invention:
The present invention relates to an improvement of a data transmission system suitable for CATV (cable television) systems.
BACKGROUND OF THE INVENTION:
1. Field of the Invention:
The present invention relates to an improvement of a data transmission system suitable for CATV (cable television) systems.
2. Related Art:
In a CATV system, video signals such as signals from VTRs or ITVs and signals of commercial broadcasting programs are transmitted from a sender through a transmission line (for example, a coaxial cable) to terminals such as tuners and video monitors.
It has become the practice in recent CATV systems that in order to cope with the diversification of informa-tion, character information blocks produced on a computerare sent to terminals in the form of character codes, along with video signals such as animation signals o-f the NTSC
system, such character information blocks being displayed in color on monitors at the terminals. Such character informa-tion blocks are usually transmitted to terminals by assign-ing appropriate frequency bands in an operating frequency range to the character information blocks and by effecting a frequency-shift-keying or phase-shift-keying modulation of the character information blocks. In order to inhibit a wide frequency band from being occupied, it is common that a plurality of character information blocks are sent serially through one frequency band.
In a CATV data transmission system of the prior art, a plurality of video sources such as VTR, ITV and received signals of commercial broadcasting programs are respectively connected to video modulators to which different carrier frequencies are assigned. The modulated video signals are sent through a transmission line to tuners in receiving terminals. Character information blocks produced on a computer are fed through an adapter to an FSK modulator and sent to the tuners along with the modulated video signals.
These video signals and character inforlllation blocks are demodulated at the tuners and displayed on monitors at ~0296~9 selected channels.
Fig. 1 shows a manner by which character information blocks are serially sent in a CATV system of the prior art.
In this figure, each information block D1, D2, ... or Di includes character information to be displayed on one picture and comprises identification data, code data and property data. If one character picture is of the size of (80 columns) x (20 rows), the amount of the code data is 1600 bytes and if each property is defined by one byte, the property data is also 1600 bytes. Fig. 1 indicates that a plurality number i of information blocks D1, D2, ..., Di are sent in one cycle.
At each receiving side, an operator designates a picture number to display, on a monitor, a character infor-mation block having the identification data corresponding tothe designated picture number. Since the information trans-mission is effected uni-directionally just as in broadcast-ing and the character information blocks are received at terminals regardless of the order in which the character information blocks are sent, the character information blocks are at all times sent cyclically.
Fig. 2 is a block diagram showing the construction of an adapter 100 used in a CATV system of the prior art.
Character information blocks D1, D2, ..., Di produced seri-ally on a computer are fed through an input interface 102 to a buffer memory 104 in an adapter 100. The stored blocks are sequentially taken out of the buffer memory 104 under the control of a data transmission control unit 106 and sent through an output interface 108 to an FSK modulator.
As could be understood from the above description, the adapter serves to store character information blocks in the buffer memory 104 and cyclically sends the stored character information blocks at a constant period. The computer provides new character information blocks to ~he adapter only when the updating of character in-formation blocks takes place. It is thus unnecessary for t~le computer to deal with the control of information transmission, which reduces a load on the computer. On the other hand, it should be noted that, even when the updating of information blocks takes place, the computer is requested to send, as character information blocks for the initial picture, the whole character information blocks for a complete picture including new character information blocks produced when the updating of information blocks takes place.
In a data transmission system of a prior art CATV
system, since the order of character information blocks produced on a computer and sent to terminals is fixed even when some character information blocks are requested to be updated, it usually takes some time for new character infor-mation blocks to reach a terminal from a sender, which results in a significant delay in the time taken to update information blocks to be displayed at monitors. Such a problem becomes more serious as the number of character pictures increases. For example, it takes 100 milliseconds to transmit a character information block for one picture, and therefore it takes lOO x 100 milliseconds to transmit character information blocks for lO0 pictures.
In order to solve this problem, Japanese Patent Public Disclosure No. 157488/87 proposes that each terminal has a means by which character information blocks received at the terminal are stored in a data memory while some information blocks are renewed with the latest ones and the character information blocks stored in the data memory and included in a designated picture are read out from the data memory to be displayed. This can shorten the time taken to display updated information blocks.
Since such a means as described above is provided at a terminal, however, each terminal must have a data extract-ing circuit, line buffers, data storing RAMs an(l the like, which makes the circuit construction complicate~.
SUMMARY OF THE I NVEN T I ON:
It is an object of the invention to provide a data transmission system wherein the updating of informatioll data is effected at a sending side withiTI a minimum delayed time and each terminal has a simple circuit construction.
In order to acllieve the above-described object, the present invention provides a data transmission system for sending a plurality of signals from a sender to at least one receiving terminal. The sender comprises:
means for storing the plurality of signals;
means for causing the stored plurality of signals to be sent in a predetermined order; and means for changing the predetermined order when the updating of signal takes place, so that an updated signal is sent with priority to said receiving terminals.
In a further aspect, the present invention resides in a data transmission system for a cable access television (CATV) system, wherein the data transmission system sends a plurality of signals from a transmitter to at least one receiving terminal, said transmitter comprising: a buffer for storing a plurality of character information blocks in a predetermined order; a transmission unit comprising means for repeatedly transmitting the plurality of character information blocks in the predetermined order in which the character information blocks are stored in the buffer over CATV transmission lines and means for transmitting video signals along with the character information blocks; means for receiving an updated character information block, the updated character information block having information for updating one of the plurality of character information blocks; means for detecting the receipt of the updated character information block; means for sending the updated character information block with priority over CATV
transmission lines; and means for replacing the character 20296~9 - 4a -information block in the buffer with the updated character information block so that the means for repeatedly transmitting will transmit the plurality of character information blocks, including the updated character information block.
In a still further aspect, the present invention resides in a data transmission system for a cable access television (CATV) system, wherein the data transmission system repeatedly sends character information blocks from a transmitter to at least one receiving terminal, said transmitter comprising: computer means for producing character information blocks arranged in a predetermined order, and for producing an updated character information block, the updated character information block having information for updating a corresponding character information block of the plurality of character information blocks; an adapter including (a) a memory for storing in a predetermined order the character information blocks produced by the computer means, (b) means for receiving the updated character information block and for replacing the character information block to be updated with the updated character information block in the corresponding area of the memory, (c) loop transmission means for transmitting the character information blocks, stored in the memory, including the updated character information block, over CATV
transmission lines in the predetermined order, and means for transmitting the updated character information block with priority.
20296~9 - 4b -In a further aspect, the present invention resides in a method of repeatedly sending character information blocks in a cable access television (CATV) system from a transmitter to at least one receiving terminal, comprising the steps of:
storing a plurality of character information blocks in a predetermined order at said transmitter; repeatedly sending the plurality of character information blocks over CATV
transmission lines in the predetermined order; detecting when the transmitter produces an updated character information block; interrupting the sending of the plurality of character information blocks in the predetermined order;
sending the updated character information block with priority to said receiving terminals; updating the corresponding character information block of the plurality of stored character information blocks with the updated character information block; and repeatedly sending the plurality of character information blocks, including the updated character information block, over CATV transmission lines in the predetermined order.
In a still further aspect, the present invention resides in a method of generating and sending character picture information from a transmitter to at least one receiving terminal, comprising the steps of: (a) producing character information blocks, each block including character information for one picture; (b) storing in a buffer the produced character information blocks in a predetermined order; (c) causing the stored character information blocks to be repeatedly sent over CATV transmission lines in the ~' -20296~9 - 4c -predetermined order; (d) producing an updated character information block; (e) interrupting the repeated sending of character information blocks in a predetermined order to immediately send an updated character information block over the CATV transmission lines; and (f) replacing the character information block to be updated with the updated character information block in a corresponding area of the buffer so that it may be later sent in step (c).
In a further aspect, the present invention resides in a CATV system having a plurality of video sources, each video source having a video modulator producing video signals, the CATV system also having a character information block transmitter producing an output, the output and the plurality of video signals forming a CATV signal for transmission, the character information block transmitter comprising: a computer means for producing at least one character information block and for producing an updated character information block; a memory for storing in a predetermined order the at least one character information block produced by the computer means and for providing an output of stored character information blocks; control means for detecting when the computer means produces the updated information block and for providing a control signal in response thereto; a switch receiving the output from the memory as a first input and receiving the updated character information block from the computer means as a second input and receiving the control signal as a control input to responsively select between the updated character 20296~9 - 4d -information block and the memory output and to provide a selected output of the character information block transmitter; and means for replacing the character information block to be updated with the updated character information block in the corresponding area of the memory.
According to the construction described above, the present invention is advantageous in that data transmission can be effected at higher speed and that the respective terminals can have a simpler structure.
Other objects and advantages of the invention will become clear from the following description taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS:
Fig. 1 shows a manner by which character information blocks are sent serially in a CATV system of the prior art;
Fig. 2 is a block diagram showing the construction of an adapter used in a sender of a prior art CATV system;
Fig. 3 schematically shows an embodiment of a data transmission system according to the present invention;
Fig. 4 shows a manner by which character information blocks are sent serially in the data transmission system according to the present invention; and Fig. 5 is a block diagram showing the construction of an adapter used in a sender of the system shown in Fig. 3.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS:
Fig. 3 is a block diagram schematically showing an - 4e - 20296~9 embodiment of a data transmission system for a CATV system in accordance with the present invention. In this figure, video signal sources la, lb, ..., ln supplying video signals from VTR's or ITV's or video signals of commercial broadcasting programs are connected to corresponding video modulators 2a, 2b, ..., 2n. Carrier frequencies f1, f2, fn are assigned to the respective video modulators so as to correspond to receiving channels.
,~ .;
202g6~9 A computer 3 produces character information blocks, each block including character information to be displayed on one picture. The character information blocks are sent through an adapter 4 to an FS~ modulator 5 where the charac-ter information blocks are frequency-shift-keying modulated using a carrier frequency fd. The video signals outpu~ from the vldeo modulators 2a, 2b, ..., 2n and the character information blocks output from the FSK modulator 5 are sent to a transmission line L. In order to compensate for attenuation in these signals, an amplifier 6 is provided in the middle of the transmission line to amplify the video signals and the character information blocks.
The amplified video signals and character information blocks are input to tu~ers 7a, 7b, ..., 7n at terminal sides and demodulated thereat to be displayed on video monitors 8a, 8b, ..., 8n at channels which operators selec~.
Fig. 4 shows a manner how character information blocks are serially sent in accordance with the present invention. This figure indicates that a series of character information blocks D1, D2, ..., Di have been sent in a first cycle and that, when the updating of the character informa-tion block Di takes place ~ust after the character informa-tion block D1 has been sent in a second cycle, the updated character information block Di is sent immediately behind the character information block D1.
Next, an operation of the adapter 4 shown in Fig. 3 will be explained with reference to Fig. 5 schematically showing the construction of the adapter 4. Character infor-mation blocks D1, D2, ..., Dn sent from the computer 3 are input through an input interface 9 to a buffer memory 10 and stored therein. Character information blocks output from the buffer memory 10 are fed through a switch 11 to an output interface 12. The buffer memory 10 and the switch 11 are controlled by a data transmission control unit 13.
~hen the updating of a character informatioll block does not take place, the stored character information blocks are taken out of the buffer memory 10 in the order in which the information blocks are stored iII the buffer memory 10, -and sent sequentially through the switch 11 to the output interface 12. On the other hand, when an updated character information block is provided from the computer 3 to the adapter 4, the data transmission control unit 13 detects this fact and interrupts the ta~ing of the character infor-mation blocks out of the buffer memory lO. The switch 11 is then changed to connect to the input interface 9 and the updated character information block is sent through the output interface 12. At the same time, the updated charac-ter information block is stored in a corresponding area inthe buffer memory lO. It is noted that whether a character information block is an updated one or not is simply decided in accordance with information supplied from the computer 3.
As can be understood from the description above, when a character picture displayed on a monitor which an operator watches should be updated to another, a character informa-tion block to be updated is immediately sent to the terminal side, which results in a shortening of the transmission time. Moreover, the transmission side is constructed such that an updated character information block is sent with priority, which serves to simplify a circuit construction of each terminal.
The present invention has been described in detail with particular reference to a certain embodiment thereof, but it should be understood that modifications and varia-tions can be effected within the scope and spirit of the invention. For example, in the embodiment describe above, the explanation has been given to the case where the computer provides an updated character information block for one picture. Instead, it is possible to send an actually updated portion of a character information block from the computer to the adapter which, in response to the updated portion, modifies a corresponding information block stored in the buffer memory and sends the modi~ied block. Such an operation can easily be accomplished by de~ining a PAR'l`IALLY
UPDATE information signal as one of the signals wllicll the computer outputs to the adapter and rewriting the bu-~fer memory when the adapter detects the PARTIALLY UPDATE
2n29649 information signal.
Further, a signal provided from the computer to the adapter is not limited to a character information block.
The computer can provide a control information signal by which a particular action is designated to be taken at the terminal sides.
In a CATV system, video signals such as signals from VTRs or ITVs and signals of commercial broadcasting programs are transmitted from a sender through a transmission line (for example, a coaxial cable) to terminals such as tuners and video monitors.
It has become the practice in recent CATV systems that in order to cope with the diversification of informa-tion, character information blocks produced on a computerare sent to terminals in the form of character codes, along with video signals such as animation signals o-f the NTSC
system, such character information blocks being displayed in color on monitors at the terminals. Such character informa-tion blocks are usually transmitted to terminals by assign-ing appropriate frequency bands in an operating frequency range to the character information blocks and by effecting a frequency-shift-keying or phase-shift-keying modulation of the character information blocks. In order to inhibit a wide frequency band from being occupied, it is common that a plurality of character information blocks are sent serially through one frequency band.
In a CATV data transmission system of the prior art, a plurality of video sources such as VTR, ITV and received signals of commercial broadcasting programs are respectively connected to video modulators to which different carrier frequencies are assigned. The modulated video signals are sent through a transmission line to tuners in receiving terminals. Character information blocks produced on a computer are fed through an adapter to an FSK modulator and sent to the tuners along with the modulated video signals.
These video signals and character inforlllation blocks are demodulated at the tuners and displayed on monitors at ~0296~9 selected channels.
Fig. 1 shows a manner by which character information blocks are serially sent in a CATV system of the prior art.
In this figure, each information block D1, D2, ... or Di includes character information to be displayed on one picture and comprises identification data, code data and property data. If one character picture is of the size of (80 columns) x (20 rows), the amount of the code data is 1600 bytes and if each property is defined by one byte, the property data is also 1600 bytes. Fig. 1 indicates that a plurality number i of information blocks D1, D2, ..., Di are sent in one cycle.
At each receiving side, an operator designates a picture number to display, on a monitor, a character infor-mation block having the identification data corresponding tothe designated picture number. Since the information trans-mission is effected uni-directionally just as in broadcast-ing and the character information blocks are received at terminals regardless of the order in which the character information blocks are sent, the character information blocks are at all times sent cyclically.
Fig. 2 is a block diagram showing the construction of an adapter 100 used in a CATV system of the prior art.
Character information blocks D1, D2, ..., Di produced seri-ally on a computer are fed through an input interface 102 to a buffer memory 104 in an adapter 100. The stored blocks are sequentially taken out of the buffer memory 104 under the control of a data transmission control unit 106 and sent through an output interface 108 to an FSK modulator.
As could be understood from the above description, the adapter serves to store character information blocks in the buffer memory 104 and cyclically sends the stored character information blocks at a constant period. The computer provides new character information blocks to ~he adapter only when the updating of character in-formation blocks takes place. It is thus unnecessary for t~le computer to deal with the control of information transmission, which reduces a load on the computer. On the other hand, it should be noted that, even when the updating of information blocks takes place, the computer is requested to send, as character information blocks for the initial picture, the whole character information blocks for a complete picture including new character information blocks produced when the updating of information blocks takes place.
In a data transmission system of a prior art CATV
system, since the order of character information blocks produced on a computer and sent to terminals is fixed even when some character information blocks are requested to be updated, it usually takes some time for new character infor-mation blocks to reach a terminal from a sender, which results in a significant delay in the time taken to update information blocks to be displayed at monitors. Such a problem becomes more serious as the number of character pictures increases. For example, it takes 100 milliseconds to transmit a character information block for one picture, and therefore it takes lOO x 100 milliseconds to transmit character information blocks for lO0 pictures.
In order to solve this problem, Japanese Patent Public Disclosure No. 157488/87 proposes that each terminal has a means by which character information blocks received at the terminal are stored in a data memory while some information blocks are renewed with the latest ones and the character information blocks stored in the data memory and included in a designated picture are read out from the data memory to be displayed. This can shorten the time taken to display updated information blocks.
Since such a means as described above is provided at a terminal, however, each terminal must have a data extract-ing circuit, line buffers, data storing RAMs an(l the like, which makes the circuit construction complicate~.
SUMMARY OF THE I NVEN T I ON:
It is an object of the invention to provide a data transmission system wherein the updating of informatioll data is effected at a sending side withiTI a minimum delayed time and each terminal has a simple circuit construction.
In order to acllieve the above-described object, the present invention provides a data transmission system for sending a plurality of signals from a sender to at least one receiving terminal. The sender comprises:
means for storing the plurality of signals;
means for causing the stored plurality of signals to be sent in a predetermined order; and means for changing the predetermined order when the updating of signal takes place, so that an updated signal is sent with priority to said receiving terminals.
In a further aspect, the present invention resides in a data transmission system for a cable access television (CATV) system, wherein the data transmission system sends a plurality of signals from a transmitter to at least one receiving terminal, said transmitter comprising: a buffer for storing a plurality of character information blocks in a predetermined order; a transmission unit comprising means for repeatedly transmitting the plurality of character information blocks in the predetermined order in which the character information blocks are stored in the buffer over CATV transmission lines and means for transmitting video signals along with the character information blocks; means for receiving an updated character information block, the updated character information block having information for updating one of the plurality of character information blocks; means for detecting the receipt of the updated character information block; means for sending the updated character information block with priority over CATV
transmission lines; and means for replacing the character 20296~9 - 4a -information block in the buffer with the updated character information block so that the means for repeatedly transmitting will transmit the plurality of character information blocks, including the updated character information block.
In a still further aspect, the present invention resides in a data transmission system for a cable access television (CATV) system, wherein the data transmission system repeatedly sends character information blocks from a transmitter to at least one receiving terminal, said transmitter comprising: computer means for producing character information blocks arranged in a predetermined order, and for producing an updated character information block, the updated character information block having information for updating a corresponding character information block of the plurality of character information blocks; an adapter including (a) a memory for storing in a predetermined order the character information blocks produced by the computer means, (b) means for receiving the updated character information block and for replacing the character information block to be updated with the updated character information block in the corresponding area of the memory, (c) loop transmission means for transmitting the character information blocks, stored in the memory, including the updated character information block, over CATV
transmission lines in the predetermined order, and means for transmitting the updated character information block with priority.
20296~9 - 4b -In a further aspect, the present invention resides in a method of repeatedly sending character information blocks in a cable access television (CATV) system from a transmitter to at least one receiving terminal, comprising the steps of:
storing a plurality of character information blocks in a predetermined order at said transmitter; repeatedly sending the plurality of character information blocks over CATV
transmission lines in the predetermined order; detecting when the transmitter produces an updated character information block; interrupting the sending of the plurality of character information blocks in the predetermined order;
sending the updated character information block with priority to said receiving terminals; updating the corresponding character information block of the plurality of stored character information blocks with the updated character information block; and repeatedly sending the plurality of character information blocks, including the updated character information block, over CATV transmission lines in the predetermined order.
In a still further aspect, the present invention resides in a method of generating and sending character picture information from a transmitter to at least one receiving terminal, comprising the steps of: (a) producing character information blocks, each block including character information for one picture; (b) storing in a buffer the produced character information blocks in a predetermined order; (c) causing the stored character information blocks to be repeatedly sent over CATV transmission lines in the ~' -20296~9 - 4c -predetermined order; (d) producing an updated character information block; (e) interrupting the repeated sending of character information blocks in a predetermined order to immediately send an updated character information block over the CATV transmission lines; and (f) replacing the character information block to be updated with the updated character information block in a corresponding area of the buffer so that it may be later sent in step (c).
In a further aspect, the present invention resides in a CATV system having a plurality of video sources, each video source having a video modulator producing video signals, the CATV system also having a character information block transmitter producing an output, the output and the plurality of video signals forming a CATV signal for transmission, the character information block transmitter comprising: a computer means for producing at least one character information block and for producing an updated character information block; a memory for storing in a predetermined order the at least one character information block produced by the computer means and for providing an output of stored character information blocks; control means for detecting when the computer means produces the updated information block and for providing a control signal in response thereto; a switch receiving the output from the memory as a first input and receiving the updated character information block from the computer means as a second input and receiving the control signal as a control input to responsively select between the updated character 20296~9 - 4d -information block and the memory output and to provide a selected output of the character information block transmitter; and means for replacing the character information block to be updated with the updated character information block in the corresponding area of the memory.
According to the construction described above, the present invention is advantageous in that data transmission can be effected at higher speed and that the respective terminals can have a simpler structure.
Other objects and advantages of the invention will become clear from the following description taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS:
Fig. 1 shows a manner by which character information blocks are sent serially in a CATV system of the prior art;
Fig. 2 is a block diagram showing the construction of an adapter used in a sender of a prior art CATV system;
Fig. 3 schematically shows an embodiment of a data transmission system according to the present invention;
Fig. 4 shows a manner by which character information blocks are sent serially in the data transmission system according to the present invention; and Fig. 5 is a block diagram showing the construction of an adapter used in a sender of the system shown in Fig. 3.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS:
Fig. 3 is a block diagram schematically showing an - 4e - 20296~9 embodiment of a data transmission system for a CATV system in accordance with the present invention. In this figure, video signal sources la, lb, ..., ln supplying video signals from VTR's or ITV's or video signals of commercial broadcasting programs are connected to corresponding video modulators 2a, 2b, ..., 2n. Carrier frequencies f1, f2, fn are assigned to the respective video modulators so as to correspond to receiving channels.
,~ .;
202g6~9 A computer 3 produces character information blocks, each block including character information to be displayed on one picture. The character information blocks are sent through an adapter 4 to an FS~ modulator 5 where the charac-ter information blocks are frequency-shift-keying modulated using a carrier frequency fd. The video signals outpu~ from the vldeo modulators 2a, 2b, ..., 2n and the character information blocks output from the FSK modulator 5 are sent to a transmission line L. In order to compensate for attenuation in these signals, an amplifier 6 is provided in the middle of the transmission line to amplify the video signals and the character information blocks.
The amplified video signals and character information blocks are input to tu~ers 7a, 7b, ..., 7n at terminal sides and demodulated thereat to be displayed on video monitors 8a, 8b, ..., 8n at channels which operators selec~.
Fig. 4 shows a manner how character information blocks are serially sent in accordance with the present invention. This figure indicates that a series of character information blocks D1, D2, ..., Di have been sent in a first cycle and that, when the updating of the character informa-tion block Di takes place ~ust after the character informa-tion block D1 has been sent in a second cycle, the updated character information block Di is sent immediately behind the character information block D1.
Next, an operation of the adapter 4 shown in Fig. 3 will be explained with reference to Fig. 5 schematically showing the construction of the adapter 4. Character infor-mation blocks D1, D2, ..., Dn sent from the computer 3 are input through an input interface 9 to a buffer memory 10 and stored therein. Character information blocks output from the buffer memory 10 are fed through a switch 11 to an output interface 12. The buffer memory 10 and the switch 11 are controlled by a data transmission control unit 13.
~hen the updating of a character informatioll block does not take place, the stored character information blocks are taken out of the buffer memory 10 in the order in which the information blocks are stored iII the buffer memory 10, -and sent sequentially through the switch 11 to the output interface 12. On the other hand, when an updated character information block is provided from the computer 3 to the adapter 4, the data transmission control unit 13 detects this fact and interrupts the ta~ing of the character infor-mation blocks out of the buffer memory lO. The switch 11 is then changed to connect to the input interface 9 and the updated character information block is sent through the output interface 12. At the same time, the updated charac-ter information block is stored in a corresponding area inthe buffer memory lO. It is noted that whether a character information block is an updated one or not is simply decided in accordance with information supplied from the computer 3.
As can be understood from the description above, when a character picture displayed on a monitor which an operator watches should be updated to another, a character informa-tion block to be updated is immediately sent to the terminal side, which results in a shortening of the transmission time. Moreover, the transmission side is constructed such that an updated character information block is sent with priority, which serves to simplify a circuit construction of each terminal.
The present invention has been described in detail with particular reference to a certain embodiment thereof, but it should be understood that modifications and varia-tions can be effected within the scope and spirit of the invention. For example, in the embodiment describe above, the explanation has been given to the case where the computer provides an updated character information block for one picture. Instead, it is possible to send an actually updated portion of a character information block from the computer to the adapter which, in response to the updated portion, modifies a corresponding information block stored in the buffer memory and sends the modi~ied block. Such an operation can easily be accomplished by de~ining a PAR'l`IALLY
UPDATE information signal as one of the signals wllicll the computer outputs to the adapter and rewriting the bu-~fer memory when the adapter detects the PARTIALLY UPDATE
2n29649 information signal.
Further, a signal provided from the computer to the adapter is not limited to a character information block.
The computer can provide a control information signal by which a particular action is designated to be taken at the terminal sides.
Claims (9)
1. In a data transmission system for a cable access television (CATV) system, wherein the data transmission system sends a plurality of signals from a transmitter to at least one receiving terminal, said transmitter comprising:
a buffer for storing a plurality of character information blocks in a predetermined order;
a transmission unit comprising means for repeatedly transmitting the plurality of character information blocks in the predetermined order in which the character information blocks are stored in the buffer over CATV
transmission lines and means for transmitting video signals along with the character information blocks;
means for receiving an updated character information block, the updated character information block having information for updating one of the plurality of character information blocks;
means for detecting the receipt of the updated character information block;
means for sending the updated character information block with priority over CATV transmission lines; and means for replacing the character information block in the buffer with the updated character information block so that the means for repeatedly transmitting will transmit the plurality of character information blocks, including the updated character information block.
a buffer for storing a plurality of character information blocks in a predetermined order;
a transmission unit comprising means for repeatedly transmitting the plurality of character information blocks in the predetermined order in which the character information blocks are stored in the buffer over CATV
transmission lines and means for transmitting video signals along with the character information blocks;
means for receiving an updated character information block, the updated character information block having information for updating one of the plurality of character information blocks;
means for detecting the receipt of the updated character information block;
means for sending the updated character information block with priority over CATV transmission lines; and means for replacing the character information block in the buffer with the updated character information block so that the means for repeatedly transmitting will transmit the plurality of character information blocks, including the updated character information block.
2. In a data transmission system for a cable access television (CATV) system, wherein the data transmission system repeatedly sends character information blocks from a transmitter to at least one receiving terminal, said transmitter comprising:
computer means for producing character information blocks arranged in a predetermined order, and for producing an updated character information block, the updated character information block having information for updating a corresponding character information block of the plurality of character information blocks;
an adapter including (a) a memory for storing in a predetermined order the character information blocks produced by the computer means, (b) means for receiving the updated character information block and for replacing the character information block to be updated with the updated character information block in the corresponding area of the memory, (c) loop transmission means for transmitting the character information blocks, stored in the memory, including the updated character information block, over CATV
transmission lines in the predetermined order, and means for transmitting the updated character information block with priority.
computer means for producing character information blocks arranged in a predetermined order, and for producing an updated character information block, the updated character information block having information for updating a corresponding character information block of the plurality of character information blocks;
an adapter including (a) a memory for storing in a predetermined order the character information blocks produced by the computer means, (b) means for receiving the updated character information block and for replacing the character information block to be updated with the updated character information block in the corresponding area of the memory, (c) loop transmission means for transmitting the character information blocks, stored in the memory, including the updated character information block, over CATV
transmission lines in the predetermined order, and means for transmitting the updated character information block with priority.
3. The transmitter as claimed in Claim 2 wherein said transmitter further comprises at least one video source for providing a video signal, and wherein the video signal and the character signal blocks are sent together to the terminals.
4. The transmitter as claimed in Claim 3, wherein said memory is a buffer memory having a capacity of storing all of the character information blocks produced by said computer means, and further comprising a switch means having an output coupled to the loop transmission means, and an input that in a first position of the switch means is coupled to an output of said buffer memory and in a second position of the switch means is coupled to an output of said computer means, said switch means being controlled so that, when the updating of a character information block does not take place, character information blocks stored in said buffer memory are taken out in the order in which such information blocks are stored, and that, when the updating of a character information block takes place, the updated character information block produced by said computer means is sent with priority to the receiving terminals.
5. A method of repeatedly sending character information blocks in a cable access television (CATV) system from a transmitter to at least one receiving terminal, comprising the steps of:
storing a plurality of character information blocks in a predetermined order at said transmitter;
repeatedly sending the plurality of character information blocks over CATV transmission lines in the predetermined order;
detecting when the transmitter produces an updated character information block;
interrupting the sending of the plurality of character information blocks in the predetermined order;
sending the updated character information block with priority to said receiving terminals;
updating the corresponding character information block of the plurality of stored character information blocks with the updated character information block; and repeatedly sending the plurality of character information blocks, including the updated character information block, over CATV transmission lines in the predetermined order.
storing a plurality of character information blocks in a predetermined order at said transmitter;
repeatedly sending the plurality of character information blocks over CATV transmission lines in the predetermined order;
detecting when the transmitter produces an updated character information block;
interrupting the sending of the plurality of character information blocks in the predetermined order;
sending the updated character information block with priority to said receiving terminals;
updating the corresponding character information block of the plurality of stored character information blocks with the updated character information block; and repeatedly sending the plurality of character information blocks, including the updated character information block, over CATV transmission lines in the predetermined order.
6. A method of generating and sending character picture information from a transmitter to at least one receiving terminal, comprising the steps of:
(a) producing character information blocks, each block including character information for one picture;
(b) storing in a buffer the produced character information blocks in a predetermined order;
(c) causing the stored character information blocks to be repeatedly sent over CATV transmission lines in the predetermined order;
(d) producing an updated character information block;
(e) interrupting the repeated sending of character information blocks in a predetermined order to immediately send an updated character information block over the CATV
transmission lines; and (f) replacing the character information block to be updated with the updated character information block in a corresponding area of the buffer so that it may be later sent in step (c).
(a) producing character information blocks, each block including character information for one picture;
(b) storing in a buffer the produced character information blocks in a predetermined order;
(c) causing the stored character information blocks to be repeatedly sent over CATV transmission lines in the predetermined order;
(d) producing an updated character information block;
(e) interrupting the repeated sending of character information blocks in a predetermined order to immediately send an updated character information block over the CATV
transmission lines; and (f) replacing the character information block to be updated with the updated character information block in a corresponding area of the buffer so that it may be later sent in step (c).
7. In a CATV system having a plurality of video sources, each video source having a video modulator producing video signals, the CATV system also having a character information block transmitter producing an output, the output and the plurality of video signals forming a CATV signal for transmission, the character information block transmitter comprising:
a computer means for producing at least one character information block and for producing an updated character information block;
a memory for storing in a predetermined order the at least one character information block produced by the computer means and for providing an output of stored character information blocks;
control means for detecting when the computer means produces the updated information block and for providing a control signal in response thereto;
a switch receiving the output from the memory as a first input and receiving the updated character information block from the computer means as a second input and receiving the control signal as a control input to responsively select between the updated character information block and the memory output and to provide a selected output of the character information block transmitter; and means for replacing the character information block to be updated with the updated character information block in the corresponding area of the memory.
a computer means for producing at least one character information block and for producing an updated character information block;
a memory for storing in a predetermined order the at least one character information block produced by the computer means and for providing an output of stored character information blocks;
control means for detecting when the computer means produces the updated information block and for providing a control signal in response thereto;
a switch receiving the output from the memory as a first input and receiving the updated character information block from the computer means as a second input and receiving the control signal as a control input to responsively select between the updated character information block and the memory output and to provide a selected output of the character information block transmitter; and means for replacing the character information block to be updated with the updated character information block in the corresponding area of the memory.
8. The CATV system of Claim 7 wherein each of the plurality of video modulators produces a video signal at a corresponding unique carrier frequency and wherein the character information block transmitter provides its output at a carrier frequency different than the carrier frequencies of the video modulators.
9. The character information block transmitter of Claim 7 further comprising means for frequency-shift-key modulating of the selected output.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP296673/1989 | 1989-11-15 | ||
| JP1296673A JP2508315B2 (en) | 1989-11-15 | 1989-11-15 | Data transmission method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2029649A1 CA2029649A1 (en) | 1991-05-16 |
| CA2029649C true CA2029649C (en) | 1996-08-13 |
Family
ID=17836594
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002029649A Expired - Fee Related CA2029649C (en) | 1989-11-15 | 1990-11-09 | Data transmission system for catv system |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US5590394A (en) |
| EP (1) | EP0432487A3 (en) |
| JP (1) | JP2508315B2 (en) |
| KR (1) | KR940004965B1 (en) |
| CA (1) | CA2029649C (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4556353B2 (en) * | 2001-06-29 | 2010-10-06 | ソニー株式会社 | Data broadcast transmission method and data broadcast transmission device |
| RU2368077C1 (en) * | 2008-02-19 | 2009-09-20 | Негосударственное образовательное учреждение Современная Гуманитарная Академия (НОУ СГА) | Method for transmission of information |
| CN112242053B (en) * | 2020-10-16 | 2022-06-28 | 中国飞机强度研究所 | Multi-type test data optimized transmission system and method |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4862268A (en) * | 1980-03-31 | 1989-08-29 | General Instrument Corporation | Addressable cable television control system with video format data transmission |
| US4868866A (en) * | 1984-12-28 | 1989-09-19 | Mcgraw-Hill Inc. | Broadcast data distribution system |
| DE3727756A1 (en) * | 1987-08-20 | 1989-03-02 | Philips Patentverwaltung | METHOD FOR PROCESSING IDENTIFICATION SIGNALS |
-
1989
- 1989-11-15 JP JP1296673A patent/JP2508315B2/en not_active Expired - Fee Related
-
1990
- 1990-11-09 CA CA002029649A patent/CA2029649C/en not_active Expired - Fee Related
- 1990-11-13 EP EP19900121725 patent/EP0432487A3/en not_active Withdrawn
- 1990-11-14 KR KR1019900018385A patent/KR940004965B1/en not_active Expired - Fee Related
-
1995
- 1995-04-03 US US08/417,432 patent/US5590394A/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JP2508315B2 (en) | 1996-06-19 |
| JPH03158042A (en) | 1991-07-08 |
| CA2029649A1 (en) | 1991-05-16 |
| KR910011050A (en) | 1991-06-29 |
| EP0432487A2 (en) | 1991-06-19 |
| EP0432487A3 (en) | 1992-08-05 |
| KR940004965B1 (en) | 1994-06-07 |
| US5590394A (en) | 1996-12-31 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed | ||
| MKLA | Lapsed |
Effective date: 20031110 |