CA1150818A - Subscription television coding system - Google Patents
Subscription television coding systemInfo
- Publication number
- CA1150818A CA1150818A CA000340211A CA340211A CA1150818A CA 1150818 A CA1150818 A CA 1150818A CA 000340211 A CA000340211 A CA 000340211A CA 340211 A CA340211 A CA 340211A CA 1150818 A CA1150818 A CA 1150818A
- Authority
- CA
- Canada
- Prior art keywords
- video
- signals
- clock
- horizontal
- suppressed
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N7/00—Television systems
- H04N7/08—Systems for the simultaneous or sequential transmission of more than one television signal, e.g. additional information signals, the signals occupying wholly or partially the same frequency band, e.g. by time division
- H04N7/087—Systems for the simultaneous or sequential transmission of more than one television signal, e.g. additional information signals, the signals occupying wholly or partially the same frequency band, e.g. by time division with signal insertion during the vertical blanking interval only
- H04N7/088—Systems for the simultaneous or sequential transmission of more than one television signal, e.g. additional information signals, the signals occupying wholly or partially the same frequency band, e.g. by time division with signal insertion during the vertical blanking interval only the inserted signal being digital
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N7/00—Television systems
- H04N7/08—Systems for the simultaneous or sequential transmission of more than one television signal, e.g. additional information signals, the signals occupying wholly or partially the same frequency band, e.g. by time division
- H04N7/084—Systems for the simultaneous or sequential transmission of more than one television signal, e.g. additional information signals, the signals occupying wholly or partially the same frequency band, e.g. by time division with signal insertion during the horizontal blanking interval only
- H04N7/085—Systems for the simultaneous or sequential transmission of more than one television signal, e.g. additional information signals, the signals occupying wholly or partially the same frequency band, e.g. by time division with signal insertion during the horizontal blanking interval only the inserted signal being digital
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N7/00—Television systems
- H04N7/16—Analogue secrecy systems; Analogue subscription systems
- H04N7/167—Systems rendering the television signal unintelligible and subsequently intelligible
- H04N7/171—Systems operating in the amplitude domain of the television signal
- H04N7/1713—Systems operating in the amplitude domain of the television signal by modifying synchronisation signals
Abstract
ABSTRACT OF THE DISCLOSURE
A method of coding and decoding video signals includes suppressing synchronization pulses during the video horizontal and vertical blanking intervals and inserting clock and address information in the suppressed intervals. Digital sound information may be inserted in the suppressed horizontal blanking intervals. At the receiver the unsynchronized video and the clock information are detected and the clock is used to control a sync pulse generator to provide the sync pulses which are then recombined with the unsynchronized video. The digital sound information is used to provide program audio which is then combined with the above-described video signal to provide a television signal usuable in a receiver.
A method of coding and decoding video signals includes suppressing synchronization pulses during the video horizontal and vertical blanking intervals and inserting clock and address information in the suppressed intervals. Digital sound information may be inserted in the suppressed horizontal blanking intervals. At the receiver the unsynchronized video and the clock information are detected and the clock is used to control a sync pulse generator to provide the sync pulses which are then recombined with the unsynchronized video. The digital sound information is used to provide program audio which is then combined with the above-described video signal to provide a television signal usuable in a receiver.
Description
115~)8~8 ~`
SU~I~IARY OF THE INVENTIC)N
The present invention relates to pay television systems and in particular to means for coding the video and/or audio signals.
A primary purpose is a subscription television system in which the video signals are coded by suppressing the horizontal and vertical synchronizing information.
Another purpose is a subscription television system of the type described in which the sync pulses during the horizontal and vertical blanking intervals are suppressed and clock and address signals are inserted therein which signals are utilized at the receiver to control a sync pulse generator.
Another purpose is a subscription television system of the type described in which digital sound may be inserted in the suppressed horizontal blanking intervals and utilized at the receiver to provide the audio portion of the television signal.
Another purpose is a subscription television system in which digital sound may be inserted in the suppressed horizontal blanking intervals to provide either the primary audio signal or an alternate sound channel.
Other purposes will appear in the ensuing specifica-tions, drawings and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is illustrated diagrammatically in the following drawings, wherein;
Figure 1 is a block diagram of the transmitting portion of the described subscription television system, and Figure 2 is a block diagram of the receiver utilized with the transmitting arrangement of Figure 1.
-la-1~50~318 ` DESCRIPTION OF THE PREFERRED EMBODIMENT
The present invention relates to subscription television systems in which over the air television signals are coded at the transmitter and include, with the video signal, signals for use in enabling and authorizing decoding circuitry at individual receivers. The synchronization pulses in the horizontal and vertical blanking intervals of the video signal are suppressed to approximately 25~ of the original amplitude. Thus the picture will be distorted in both horizontal and vertical directions and will be completely unusable unless the required decoding equipment is operable.
Clock signals for operating the sync pulse generator in each receiver are inserted into the vertical blanking intervals.
In addition authorization or address signals for enabling the decoding equipment are also inserted in the vertical blanking intervals. The audio portion of the television signal may be clear or not coded. In the alternative, the audio portion can be digitized and the digital sound information inserted in the horizontal blanking intervals. In the later instance, the sound is reconstituted at each receiver and the program audio is then recombined, at the receiver, with the decoded video. As a further alternative, audio information can be included in the described horizontal blanking intervals to provide an alternate sound channel.
In Figure l the program video signal is provided on line 10 and the audio signal on line 12. The video signal provides one input for a sync processor 14 and for a gate 16.
The sync processor will provide several independent signals for use as described. The first output, along line 18 to gate 16, is effective to operate gate 16 in a manner to suppress the sync pulses during the vertical interval of the video signal. Thus the signal at the output of gate 16 is the normal video signal with the vertical interval suppressed, preferably to a level of approximately 25 percent of its original amplitude.
llS0818 The second output from sync processor 14, along line 20, is connected to gate 22. The other input for gate 22 is the video signal from gate 16. The signal from sync processor 14 provided at gate 22 is effective to suppress the horizontal blanking interval to approximately 25 percent of its original amplitude. Thus, the output from gate 22 is the original video signal with both the horizontal and vertical blanking intervals suppressed to approximately 25 percent of their original amplitude.
A clock generator is indicated at 24 and may provide a clock signal of 3.58 mhz. One output from clock generator 24 goes to divide circuit 26 which provides an output signal at 31.5 khz which is the sound sampling frequency. To digitize sound, with a maximum frequency of 12 khz, it is necessary to have a sampling frequency ~f at least 24 khz. For a aynamic range of 48 dB there should be 8 bits so that the minimum bit rate will be 192 K bit/second. Because the synchronization frequency is approximately 15 khz and thè sampling frequency should be at least 24 khz it has been determined to combine two sound samples into each horizontal blanking interval.
Delay circuit 28 is effective to delay every other or alternate sound samples as provided at the sampling frequency of 31.5 khz from divide circuit 26. Thus, each horizontal blanking interval will have two sound samples. In order to properly reconstitute the audio signal it will be necessary~that at the decoder one-half of the total number of bits inserted in each horizontal blanking interval be delayed. In practice it has been deter-mined that 24 bits per horizontal blanking interval time slot may be utilized with 2 eight bit sound samples and the remaining 8 bits utilized for synchronization and control. Thus, the signal from delay circuit 28 will be as described and will provide one input for gate 30. At the other input for gate 30 is a timing signal from sync processor 14 along line 32 which liS08~8 will cause insertion of the described digital sound information into the horizontal blanking intervals.
Clock generator 24 is connected to a divide circuit 38 which provides clock signals for utilization at the receiver at 4/7 of the clock frequency of 3.58 mhz. In this connection, the frequencies provided herein are only illustrative and the invention should not be limited thereto. The output from divide circuit 38 is connected to line modulator 36 which has a further input, along line 34, from sync processor 14 which is ~tilized to control the insertion of the clock signals in the first nine lines of the suppressed vertical blanking interval. Line mod-ulator 36 receives, from gate 30, the video signal with suppressed horizontal and vertical blanking intervals and with the inserted ~igital sound. The output from modulator 36 will be the described signal with the addition of clock signals during the first nine lines of the suppressed vertical blanking i~terval.
A line counter 40 is connected to sync processor 14 and has its output connected to a computer 42. The output from computer 42 is connected to an address gate 44. Computer 42 contains the addresses of all subscribers authorized to receive subscription programs. Not all addresses will be sent in every vertical blanking inter~al, but rather they will be sequentially fed by the computer to the address gate for insertion in the vertical blanking interval after the clock signals in the first nine lines. Assuming 48 bits per address, and one address per line, with twelve unused lines, it is possible to insert twelve addresses in each vertical blanking interval. In normal opera-tion, however, prior to the actual transmission of the subscription program, all receivers will be addressed as it will be possible to utilize the entire video transmission. The addressing during each vertical blanking interval can be utilized to continually enable the decoders in each receiver once they have been initially-enabled by a transmission prior to the start of the subscription 11508~8 program. Thus, the output from address gate 44 will be the above-described video signal, with the digital sound inserted in the horizontal blanking interval and with address or enabling information in the vertical blanking interval after the above-described clock signals. This signal is sent to transmitter 46 which will then transmit the described signal over the air for reception by those subscribers having the necessary decoding equipment.
- Figure 2 illustrates the decoding apparatus at the receiver. A tuner 50 which may be either a UHF or VHF tuner is connected to an IF filter 52 providing an approximate 45 mhz output signal which is in turn passea to a video detector 54.
The output from detector 54 is the above-described video signal and is connected to a decoder 56 and a combining circuit 58.
Decoder 56 will provide one output of the above-describea clock signal along line 60 to sync generator 62., The output from sync generator 62 which will be the vertical and horizontal sync pulses suppressed at the-transmitter is sent to combining circuit 58 whose output is thus the reconstituted video with appropriate sync signals. Sync generator 62 will be continuously providing normal sync pulses, but the clock signals from decoder 56 are necessary to properly coordinate the timing of the sync generator and the video signal.
- A second output from decoder 56 is the digital sound information which is connected to a digital to analog converter 64. The output from converter 64 will be the reconstituted audio signal. A 4.5 mhz oscillator 66 is connected to an FM
modulator 68 which receives the audio signal from converter 64 with the output from modulator 68 being the audio portion of the original television signal at a 4.5 mhz frequency. This signal is passed to a combining circuit 70 which receives the combined video signal from combining circuit 58. Thus, the output from combining circuit 70 is the video and audio portions, properly decoded, of the original television signal.
11508~8 The third output from decoder 56, the address or enabling information which had been previously inserted in the vertical blanking interval is passed to an address authorization decoder 72 which compares the decoded address with the address of the receiver. If there is comparison, switch t4 is enabled to permit modulator 76 to function in the appropriate manner.
Modulator 76 changes the frequency of the video and audio signals from combining circuit 70 to an RF signal at the appropriate frequency for use in a television set. Normally this will be channel three or four, unused channels in many areas. The output from modulator 76, a channel three or channel four television signal will be passed through filter 78 and then to the television receiver.
The subscription television system described herein not only provides adequate safeguards to preventing piracy of the signal, but does so in a reliable and relatively uncomplex manner. The vertical and horizontal synchroni,zation is removed from the video signal and is provided at the receiver by an independent sync generator,the timing of which is controlled by clock signals forming a part of the transmitted video.
Substantially complete picture di'stortion is effected by removal of both horizontal and vertical synchronization.
The audio may be coded as described, in the form of digital sound. In the alternative, the audio may be transmitted clear, without coding. In such event the horizontal blanking interval can be used to provide an alternate sound channel, or it can have no coding information superimposed thereon~ As another alternative, the clock and address information described as being inserted in the vertical interval can be inserted in the horizontal blanking interval. Thus it is possible to utilize the horizontal blanking interval for an alternate sound channel, for coded audio information, for no signal at all or for additional code data supplementing that superimposed on the vertical blanking interval.
~` 11508~8 Whereas the preferred form of the invention has been shown and described herein, it should be realized that there may be many modifications, substitutions, and alterations thereto.
SU~I~IARY OF THE INVENTIC)N
The present invention relates to pay television systems and in particular to means for coding the video and/or audio signals.
A primary purpose is a subscription television system in which the video signals are coded by suppressing the horizontal and vertical synchronizing information.
Another purpose is a subscription television system of the type described in which the sync pulses during the horizontal and vertical blanking intervals are suppressed and clock and address signals are inserted therein which signals are utilized at the receiver to control a sync pulse generator.
Another purpose is a subscription television system of the type described in which digital sound may be inserted in the suppressed horizontal blanking intervals and utilized at the receiver to provide the audio portion of the television signal.
Another purpose is a subscription television system in which digital sound may be inserted in the suppressed horizontal blanking intervals to provide either the primary audio signal or an alternate sound channel.
Other purposes will appear in the ensuing specifica-tions, drawings and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is illustrated diagrammatically in the following drawings, wherein;
Figure 1 is a block diagram of the transmitting portion of the described subscription television system, and Figure 2 is a block diagram of the receiver utilized with the transmitting arrangement of Figure 1.
-la-1~50~318 ` DESCRIPTION OF THE PREFERRED EMBODIMENT
The present invention relates to subscription television systems in which over the air television signals are coded at the transmitter and include, with the video signal, signals for use in enabling and authorizing decoding circuitry at individual receivers. The synchronization pulses in the horizontal and vertical blanking intervals of the video signal are suppressed to approximately 25~ of the original amplitude. Thus the picture will be distorted in both horizontal and vertical directions and will be completely unusable unless the required decoding equipment is operable.
Clock signals for operating the sync pulse generator in each receiver are inserted into the vertical blanking intervals.
In addition authorization or address signals for enabling the decoding equipment are also inserted in the vertical blanking intervals. The audio portion of the television signal may be clear or not coded. In the alternative, the audio portion can be digitized and the digital sound information inserted in the horizontal blanking intervals. In the later instance, the sound is reconstituted at each receiver and the program audio is then recombined, at the receiver, with the decoded video. As a further alternative, audio information can be included in the described horizontal blanking intervals to provide an alternate sound channel.
In Figure l the program video signal is provided on line 10 and the audio signal on line 12. The video signal provides one input for a sync processor 14 and for a gate 16.
The sync processor will provide several independent signals for use as described. The first output, along line 18 to gate 16, is effective to operate gate 16 in a manner to suppress the sync pulses during the vertical interval of the video signal. Thus the signal at the output of gate 16 is the normal video signal with the vertical interval suppressed, preferably to a level of approximately 25 percent of its original amplitude.
llS0818 The second output from sync processor 14, along line 20, is connected to gate 22. The other input for gate 22 is the video signal from gate 16. The signal from sync processor 14 provided at gate 22 is effective to suppress the horizontal blanking interval to approximately 25 percent of its original amplitude. Thus, the output from gate 22 is the original video signal with both the horizontal and vertical blanking intervals suppressed to approximately 25 percent of their original amplitude.
A clock generator is indicated at 24 and may provide a clock signal of 3.58 mhz. One output from clock generator 24 goes to divide circuit 26 which provides an output signal at 31.5 khz which is the sound sampling frequency. To digitize sound, with a maximum frequency of 12 khz, it is necessary to have a sampling frequency ~f at least 24 khz. For a aynamic range of 48 dB there should be 8 bits so that the minimum bit rate will be 192 K bit/second. Because the synchronization frequency is approximately 15 khz and thè sampling frequency should be at least 24 khz it has been determined to combine two sound samples into each horizontal blanking interval.
Delay circuit 28 is effective to delay every other or alternate sound samples as provided at the sampling frequency of 31.5 khz from divide circuit 26. Thus, each horizontal blanking interval will have two sound samples. In order to properly reconstitute the audio signal it will be necessary~that at the decoder one-half of the total number of bits inserted in each horizontal blanking interval be delayed. In practice it has been deter-mined that 24 bits per horizontal blanking interval time slot may be utilized with 2 eight bit sound samples and the remaining 8 bits utilized for synchronization and control. Thus, the signal from delay circuit 28 will be as described and will provide one input for gate 30. At the other input for gate 30 is a timing signal from sync processor 14 along line 32 which liS08~8 will cause insertion of the described digital sound information into the horizontal blanking intervals.
Clock generator 24 is connected to a divide circuit 38 which provides clock signals for utilization at the receiver at 4/7 of the clock frequency of 3.58 mhz. In this connection, the frequencies provided herein are only illustrative and the invention should not be limited thereto. The output from divide circuit 38 is connected to line modulator 36 which has a further input, along line 34, from sync processor 14 which is ~tilized to control the insertion of the clock signals in the first nine lines of the suppressed vertical blanking interval. Line mod-ulator 36 receives, from gate 30, the video signal with suppressed horizontal and vertical blanking intervals and with the inserted ~igital sound. The output from modulator 36 will be the described signal with the addition of clock signals during the first nine lines of the suppressed vertical blanking i~terval.
A line counter 40 is connected to sync processor 14 and has its output connected to a computer 42. The output from computer 42 is connected to an address gate 44. Computer 42 contains the addresses of all subscribers authorized to receive subscription programs. Not all addresses will be sent in every vertical blanking inter~al, but rather they will be sequentially fed by the computer to the address gate for insertion in the vertical blanking interval after the clock signals in the first nine lines. Assuming 48 bits per address, and one address per line, with twelve unused lines, it is possible to insert twelve addresses in each vertical blanking interval. In normal opera-tion, however, prior to the actual transmission of the subscription program, all receivers will be addressed as it will be possible to utilize the entire video transmission. The addressing during each vertical blanking interval can be utilized to continually enable the decoders in each receiver once they have been initially-enabled by a transmission prior to the start of the subscription 11508~8 program. Thus, the output from address gate 44 will be the above-described video signal, with the digital sound inserted in the horizontal blanking interval and with address or enabling information in the vertical blanking interval after the above-described clock signals. This signal is sent to transmitter 46 which will then transmit the described signal over the air for reception by those subscribers having the necessary decoding equipment.
- Figure 2 illustrates the decoding apparatus at the receiver. A tuner 50 which may be either a UHF or VHF tuner is connected to an IF filter 52 providing an approximate 45 mhz output signal which is in turn passea to a video detector 54.
The output from detector 54 is the above-described video signal and is connected to a decoder 56 and a combining circuit 58.
Decoder 56 will provide one output of the above-describea clock signal along line 60 to sync generator 62., The output from sync generator 62 which will be the vertical and horizontal sync pulses suppressed at the-transmitter is sent to combining circuit 58 whose output is thus the reconstituted video with appropriate sync signals. Sync generator 62 will be continuously providing normal sync pulses, but the clock signals from decoder 56 are necessary to properly coordinate the timing of the sync generator and the video signal.
- A second output from decoder 56 is the digital sound information which is connected to a digital to analog converter 64. The output from converter 64 will be the reconstituted audio signal. A 4.5 mhz oscillator 66 is connected to an FM
modulator 68 which receives the audio signal from converter 64 with the output from modulator 68 being the audio portion of the original television signal at a 4.5 mhz frequency. This signal is passed to a combining circuit 70 which receives the combined video signal from combining circuit 58. Thus, the output from combining circuit 70 is the video and audio portions, properly decoded, of the original television signal.
11508~8 The third output from decoder 56, the address or enabling information which had been previously inserted in the vertical blanking interval is passed to an address authorization decoder 72 which compares the decoded address with the address of the receiver. If there is comparison, switch t4 is enabled to permit modulator 76 to function in the appropriate manner.
Modulator 76 changes the frequency of the video and audio signals from combining circuit 70 to an RF signal at the appropriate frequency for use in a television set. Normally this will be channel three or four, unused channels in many areas. The output from modulator 76, a channel three or channel four television signal will be passed through filter 78 and then to the television receiver.
The subscription television system described herein not only provides adequate safeguards to preventing piracy of the signal, but does so in a reliable and relatively uncomplex manner. The vertical and horizontal synchroni,zation is removed from the video signal and is provided at the receiver by an independent sync generator,the timing of which is controlled by clock signals forming a part of the transmitted video.
Substantially complete picture di'stortion is effected by removal of both horizontal and vertical synchronization.
The audio may be coded as described, in the form of digital sound. In the alternative, the audio may be transmitted clear, without coding. In such event the horizontal blanking interval can be used to provide an alternate sound channel, or it can have no coding information superimposed thereon~ As another alternative, the clock and address information described as being inserted in the vertical interval can be inserted in the horizontal blanking interval. Thus it is possible to utilize the horizontal blanking interval for an alternate sound channel, for coded audio information, for no signal at all or for additional code data supplementing that superimposed on the vertical blanking interval.
~` 11508~8 Whereas the preferred form of the invention has been shown and described herein, it should be realized that there may be many modifications, substitutions, and alterations thereto.
Claims (8)
1. A method of coding and decoding video signals in-cluding the steps of:
(a) at the transmitter suppressing synchronizing pulses during the video horizontal and vertical blanking intervals, and inserting clock information in suppressed intervals, (b) at the receiver detecting the unsynchronized video and the clock information, using said detected clock information to control a sync pulse generator which independently and in response to said clock information generates sync pulses for the video horizontal and vertical blanking intervals and combin-ing the detected video and independently generated sync pulses to provide a usable video signal.
(a) at the transmitter suppressing synchronizing pulses during the video horizontal and vertical blanking intervals, and inserting clock information in suppressed intervals, (b) at the receiver detecting the unsynchronized video and the clock information, using said detected clock information to control a sync pulse generator which independently and in response to said clock information generates sync pulses for the video horizontal and vertical blanking intervals and combin-ing the detected video and independently generated sync pulses to provide a usable video signal.
2. The method of claim 1 further characterized in that the clock information is only inserted in the suppressed vertical blanking intervals.
3. The method of claim 1 further characterized by and including the step of inserting address signals in the sup-pressed blanking intervals at the transmitter, and using said address signals in the receiver decoding process.
4. The method of claim 1 further characterized by and including the step of inserting digital sound information in the suppressed horizontal blanking intervals at the trans-mitter and detecting said digital sound information at the re-ceiver.
5. A method of detecting and reforming video signals in which the horizontal and vertical blanking intervals have been suppressed and in which clock information and authorization signals have been inserted in suppressed blanking intervals in-cluding the steps of:
(a) detecting the unsynchronized video, clock and authorization signals, (b) using said clock signals to control a sync pulse generator which independently and in response to said clock in-formation generates sync pulses for the video horizontal and vertical blanking intervals, (c) and recombining the unsynchronized video and in-dependently generated sync pulses.
(a) detecting the unsynchronized video, clock and authorization signals, (b) using said clock signals to control a sync pulse generator which independently and in response to said clock in-formation generates sync pulses for the video horizontal and vertical blanking intervals, (c) and recombining the unsynchronized video and in-dependently generated sync pulses.
6. The method of claim 5 further characterized in that digital sound signals are inserted in the horizontal blank-ing intervals of the video signal and including the steps, at the receiver, of detecting the digital sound signals, providing an audio signal therefrom, and combining the audio and video signals.
7. Apparatus for decoding a coded television signal in which the synchronizing pulses during the video horizontal and vertical blanking intervals have been suppressed and in which clock signals have been inserted in the suppressed blanking in-tervals, including:
(a) means for detecting the clock signals, (b) independent sync pulse generating mean sconnected to said detecting means and operable by said clock signals to generate sync pulses for the video horizontal and vertical blank-ing intervals, and (c) means for combining the independently generated sync pulses from said pulse generating means and the video signal having suppressed synchronized pulses to provide a usable tele-vision signal.
(a) means for detecting the clock signals, (b) independent sync pulse generating mean sconnected to said detecting means and operable by said clock signals to generate sync pulses for the video horizontal and vertical blank-ing intervals, and (c) means for combining the independently generated sync pulses from said pulse generating means and the video signal having suppressed synchronized pulses to provide a usable tele-vision signal.
8. The apparatus of claim 7 further characterized in that said coded television signal includes digital sound in-formation inserted in the horizontal blanking intervals, said decoding means including:
(d) means for detecting said digital sound information and for providing therefrom a reconstituted audio signal, and (e) means for combining said reconstituted audio signal with said video signal.
(d) means for detecting said digital sound information and for providing therefrom a reconstituted audio signal, and (e) means for combining said reconstituted audio signal with said video signal.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US96594078A | 1978-12-04 | 1978-12-04 | |
| US965,940 | 1978-12-04 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1150818A true CA1150818A (en) | 1983-07-26 |
Family
ID=25510704
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000340211A Expired CA1150818A (en) | 1978-12-04 | 1979-11-20 | Subscription television coding system |
Country Status (12)
| Country | Link |
|---|---|
| JP (2) | JPS5588481A (en) |
| AU (1) | AU526049B2 (en) |
| BR (1) | BR7907803A (en) |
| CA (1) | CA1150818A (en) |
| CH (1) | CH661398A5 (en) |
| DE (1) | DE2947943C2 (en) |
| FR (1) | FR2443778B1 (en) |
| GB (1) | GB2038137B (en) |
| GR (1) | GR82329B (en) |
| IL (1) | IL58735A (en) |
| MX (1) | MX147755A (en) |
| NL (1) | NL188137C (en) |
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|---|---|---|---|---|
| US4594609A (en) * | 1983-06-30 | 1986-06-10 | Viewstar Inc. | Scrambling system for television video signal |
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| CA1338158C (en) * | 1982-07-15 | 1996-03-12 | John D. Lowry | Encryption and decryption (scrambling and unscrambling) of video signals |
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| EP0119751B1 (en) * | 1983-02-18 | 1987-09-30 | Sanyo Electric Co., Ltd. | Scrambling system of television signal |
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| FR2572612B1 (en) * | 1984-10-31 | 1986-12-26 | Cgv Comp Gen Videotech | INTERFACE BETWEEN VIDEO DECODER AND TELEVISION RECEIVER |
| US4815129A (en) * | 1985-01-02 | 1989-03-21 | General Instrument Corp. | Video encryption system |
| DE3638554A1 (en) * | 1986-11-12 | 1988-05-26 | Siemens Ag | Method and arrangement for coding digital video signals |
| GB2216359B (en) * | 1988-03-18 | 1992-05-20 | Marconi Gec Ltd | Synchronisation |
| AU6013394A (en) * | 1993-01-15 | 1994-08-15 | Nauchno-Proizvodstvennaya Firma 'elektronika Ltd.' | Method of relaying data via teevision channels and a system for carrying out same |
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| JPS5120623A (en) * | 1974-08-14 | 1976-02-19 | Matsushita Electric Ind Co Ltd | SHINGODENSO HOSHIKI |
| JPS5169927A (en) * | 1974-12-13 | 1976-06-17 | Fujitsu Ltd | TEREBIJON FUKUGOEIZO SHINGOHOSHIKI |
| FR2313825A1 (en) * | 1975-06-06 | 1976-12-31 | Telediffusion Fse | DATA DISSEMINATION SYSTEM |
| US4095258A (en) * | 1976-10-15 | 1978-06-13 | Blonder-Tongue Laboratories, Inc. | Apparatus for decoding scrambled television and similar transmissions |
| JPS53113427A (en) * | 1977-03-15 | 1978-10-03 | Matsushita Electric Ind Co Ltd | Sampling clock reproducer |
-
1979
- 1979-11-16 IL IL58735A patent/IL58735A/en unknown
- 1979-11-20 CA CA000340211A patent/CA1150818A/en not_active Expired
- 1979-11-20 GR GR60551A patent/GR82329B/el unknown
- 1979-11-22 AU AU53097/79A patent/AU526049B2/en not_active Expired
- 1979-11-26 NL NLAANVRAGE7908569,A patent/NL188137C/en not_active IP Right Cessation
- 1979-11-27 GB GB7940978A patent/GB2038137B/en not_active Expired
- 1979-11-28 DE DE2947943A patent/DE2947943C2/en not_active Expired
- 1979-11-29 CH CH10621/79A patent/CH661398A5/en not_active IP Right Cessation
- 1979-11-30 BR BR7907803A patent/BR7907803A/en unknown
- 1979-12-03 FR FR7929682A patent/FR2443778B1/en not_active Expired
- 1979-12-04 MX MX180309A patent/MX147755A/en unknown
- 1979-12-04 JP JP15732979A patent/JPS5588481A/en active Pending
-
1988
- 1988-01-18 JP JP1988004588U patent/JPS63131287U/ja active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4594609A (en) * | 1983-06-30 | 1986-06-10 | Viewstar Inc. | Scrambling system for television video signal |
Also Published As
| Publication number | Publication date |
|---|---|
| AU5309779A (en) | 1980-06-12 |
| NL7908569A (en) | 1980-06-06 |
| JPS63131287U (en) | 1988-08-26 |
| DE2947943A1 (en) | 1980-06-26 |
| DE2947943C2 (en) | 1985-04-18 |
| GB2038137A (en) | 1980-07-16 |
| IL58735A (en) | 1982-01-31 |
| FR2443778B1 (en) | 1986-04-11 |
| MX147755A (en) | 1983-01-10 |
| AU526049B2 (en) | 1982-12-16 |
| FR2443778A1 (en) | 1980-07-04 |
| GR82329B (en) | 1984-12-13 |
| CH661398A5 (en) | 1987-07-15 |
| IL58735A0 (en) | 1980-02-29 |
| BR7907803A (en) | 1980-07-29 |
| NL188137C (en) | 1992-04-01 |
| JPS5588481A (en) | 1980-07-04 |
| NL188137B (en) | 1991-11-01 |
| GB2038137B (en) | 1983-04-13 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry | ||
| MKEX | Expiry |
Effective date: 20000726 |