MXPA97008661A - Dynamic relocation of deserved data channel - Google Patents

Abstract

The present invention relates to a method and apparatus for preventing the unauthorized de-distortion of cable programming includes selective relocation of the service data channel within the vertical bleaching range, thereby preventing the unauthorized de-distortion of conventional de-distortion programs.

Description

DYNAMIC RELOCATION OF THE SERVICE DATA CHANNEL.

DESCRIPTION.

BACKGROUND OF THE INVENTION.

Field of the invention.

This invention relates to systems for removing distortion in cable television broadcasts. More particularly, the invention relates to a cable television system, which relocates the service data channel to prevent the distortion of unauthorized persons from premium and pay-per-view programs.

Description of the related art.

Distortion and de-distortion systems are widely used by CATV system operators to control subscriber access to premium channels and pay per event. The signals that have video and audio in certain channels are distorted before the transmission from the main terminal of the operator of the CATV system and subsequently they de-distinguish in the house of authorized subscribers. A device, commonly referred to as a de-divider, or a fixing terminal, is installed in the subscriber's home to restore distorted signals if the subscriber is authorized to receive the channel.

Many CATV fixing terminals use a service data channel and a control data channel to determine if a fixing terminal is authorized to de-distinguish a selected channel. A first authorization code is transmitted on the control data channel, which is dedicated to transmit data and is not associated with any broadcast channel. The control data channel originates from the main terminal of the CATV system and provides specific information to the CATV system such as data for the video programming guide, data forwarded to the fixing terminal and other control information, such as the set of codes for services where the fixation terminal is authorized to receive.

The locking terminal separately receives a second authorization code which is transmitted on the service data channel for detection by the fixing terminal. This authorized code is inserted by the CATV operator on line 18 of the vertical bleaching interval (IBV), which is part of each frame of a video signal transmitted on a broadcast channel. The fixation terminal compares the second authorization code sent on the service data channel with a first authorization code detected on the control data channel. If these two codes are identical, the fixing terminal is authorized to begin to de-distort the received signal.

The integrity of the current systems using the aforementioned authorization scheme has been subverted. Illegal or "pirate" fixation boxes can be configured to authorize the de-diffusion of a channel regardless of the authorization code received on line 18 in the IBV. Additionally, if the control data channel is compromised, the fixation terminal will authorize any detected code on line 18, thereby allowing the illegal view of a program.

It is desirable to have a system that prevents access to authorized codes and prohibits unauthorized de-distinguishing of signals having video and audio programs.

THE INVENTION.

A CATV system for preventing unauthorized de-distinguishing of video and audio signals comprises a main terminal for providing a plurality of distorted video and audio program signals and a subscriber's terminal for de-distinguishing the signals. The main terminal provides a first authorization code on a separate control data channel and a second authorization code on a service data channel that is within the IBV of the broadcast signals. The service data channel information is selectively located within the IBV. The fixation terminal determines the location of the service data channel and authorizes the de-distinguishing of the signals having audio and video content based on the authorization codes transmitted on the service data channel and the control data channel.

In accordance with the foregoing, it is an object of the present invention to provide a system that selectively relocates the service data channel within the vertical bleaching range to prevent unauthorized de-distortion of audio and video signals.

Other objects and advantages of the present invention will be apparent to those skilled in the art upon reading the following detailed description of the preferred embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a simplified view of a CATV transmission infrastructure.

Figure 2 is a graph of the transmission spectrum upstream and downstream.

Figure 3 is a block diagram of a fixing terminal made in accordance with the present invention.

Figure 4 is the use of the prior art of the IBV of a video frame.

Figure 5 is a block diagram of a main terminal made in accordance with the present invention.

Figure 6 is a flow chart of a prior art reading information method.

Figure 7 is a flowchart of the method of relocating the service data channel according to the present invention.

Figure 8 is a flow chart of the method for detecting the service data channel information within the IBV.

Figure 9 is a flow diagram of a method for determining whether the de-distortion of the video signal will be performed.

Figure 10 is a flow chart of an alternative embodiment of the present invention, incorporating a dynamically relocatable service data channel.

Figure 11 is a flow diagram of a second alternative embodiment of the present invention, incorporating a dynamically relocatable service data channel; Y Figure 12 is a flow diagram of a third alternative embodiment of the present invention, incorporating a dynamically relocatable service data channel DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The preferred embodiment will be described with reference to the figures of the accompanying drawings, in which like numerals represent like elements.

A CATV communication system 10 incorporating the present invention is shown in Figure 1. The communication system 10 generally comprises one or more video information providers 14, communicating via satellite with chains 23 with a plurality of terminals 12. main. Each terminal 12, in turn, communicates with a plurality of fixing terminals 20, one or more of which is located in the house of a subscriber. The fixing terminal 20 receives the transmissions from the main terminal 12 through the CATV transmition network 22. The CATV transmission network 22 may comprise a common normal coaxial network, a hybrid fiber-coax network or a "wireless cable" network employing microwave antennas and receivers. The fixing terminal 20 provides the user interface between the television 21 of the subscriber and the communication system 10.

As shown in Figure 2, the transmission spectrum 41 typically extends to 1 GHz. In order to provide a bidirectional communication flow over the cable transmission network 22 between the main terminal 12 and the fixing terminals 20, the transmission spectrum 41 is divided into two paths. A downstream signal path originating from the main terminal 12 typically employs a bandwidth 28 downstream of frequencies above 50 MHz. An upstream path originating at the fixing terminals 20 comprises a width band 26 upstream of frequencies from 5 to 50 MHz. The downstream bandwidth 28 is further divided into 6 MHz broadcast channels 32 which are used primarily to transmit analog or digital video broadcasts and their analog audio programs or digital partners.

With reference to Figure 3, a fixing terminal made in accordance with the present invention is shown. The fixing terminal 20 includes a system processor 100, a tuner 112, a modem 102, video and audio processors 116 and 118, memories 106 and 110 and an infrared remote interface (IR). A manifold 103 of the system facilitates communications between the components within the fixing terminal 20.

The processor 100 of the system provides complete control of the fixing terminal 20. The processor 100 of the system receives the read-only memory (ROM) 106 boot functions upon energization and stores the control information and other data sent from the main terminal 12 in the random access memories (RAM) 110, which preference are non-volatile. As will be explained in detail hereinafter, the control information of the main terminal 12 includes authorization codes sent on CDC and the service data channel that are stored in RAM 110.

The tuner 112 responds to the frequency of the channel selected by the consumer to remove the carrier signal. The audio and video content is processed through the audio processor 116 and the video processor 118 respectively in a manner that is well known to those skilled in the art. The baseband video signal is typically placed on a second carrier frequency corresponding to the television channels 3 or 4 to provide a video output 120.

The left and right channel audio inputs 122 and 124 are also provided for input into a stereo (not shown) or the audio inputs of a television 21 of the consumer thus equipped.

The modem 102 provides a data interface between the system processor 100 and the main CATV terminal 12. The modem 102 receives the data transmissions outside the band of the main terminal 12. Optionally, if bidirectional communication is desired, the modem 102 can transmit upstream communications from the fixing terminal 20 to the main terminal 12. However, those skilled in the art will recognize that bidirectional communication is not required for the present invention.

The fixing terminal 20 is controlled through the infrared remote control (IR) interface 104. The interface 104 IR comprises an IR signal emitter which sends the IR control signals to the IR receiver located within the fixing terminal 20. Then the received control signals are sent to the processor 100 of the system. They can also be used for control of the fixing terminal 20, push-button controls placed on the outside of the fixing terminal 20.

The fixation terminal 20 receives information from the main terminal 12 that includes data in the band within the IBV of the programs transmitted on broadcast channels 32 and out-of-band information on a control data channel (CDC) 34. The processor 100 of the system in conjunction with the audio processor 116 and the video processor 118 de-distorts the baseband signal of the selected channel 32 if the subscriber is an authorized user as will be described in detail hereafter. The audio and video processors 116 and 118 process the band data of the channel 32 selected for reception (see and hear) by the subscriber.

Each fixing terminal 20 includes a unique digital identifier, such as a digital address, which allows the cable operator to send commands directly to an individual fixing terminal 20. These commands are typically called directional controls. The directional controls are carried via an out-of-band directional data stream, i.e. CDC 34.

With reference to Figure 4, the prior art using IBV is shown. Embedded within each video frame 18 sent on broadcast channel 32 is the specific information. The complete video image, called a frame, is made up of two fields that each contain two hundred and sixty-two and a half horizontal scan lines. After each field of two hundred and sixty-two and one-half horizontal lines is scanned, the explorer beam returns to the top of the screen to begin exploring the next field. The retrace time is called the IBV. During the vertical blanking interval, video program information is not included in the composite video signal. The last IBV for a time equal to 21 horizontal lines or 1333.5 microseconds and comprises a plurality of horizontal lines, with each line containing up to 24 bits of information. The IBV can also include special reference signals that are located on selected lines of the IBV. Several common signals placed along the IBV include the vertical interval test signal on lines 17 and 18, the vertical interval reference signal on line 19 and the closed feedback signal on line 21.

With reference to Figure 5, a main terminal 12 made in accordance with the teachings of the present invention is shown. The main terminal 12 receives video, audio and data from the remote service providers 70 and retransmits this information on the CATV transmission network 22 in a manner that is well known to those skilled in the art. The main terminal 12 can also be the source of the local program. The main terminal 12 includes an encoder 61 comprising a microprocessor 60 which is coupled to an electronic storage device 62, such as a PC "hard drive" or any other suitable memory type and a data transceiver 64. The data transceiver 64 is further coupled with a service data inserter 68 which combines the data with the audio, video and data content 66 for transmission to the consumers on the CATV network 22. The data transceiver 64 is also directly coupled with the CATV network 22 to transmit and receive control data. The service data channel information and any other information inserted into the IBV of the video signal is inserted by the service data channel inserter 68. The insertion is performed with the "on / off" key at a disturbed frequency of color as is well known to those skilled in the art. A distorting module 69 distorts the signals before the tanssion on the network 22.

With reference to Figure 6, in order to properly detect the location of the service data channel within the IBV, many binding terminals typically seek an absence of color distortion, or a gap, indicating the occurrence of the IBV. (step 235). This space occurs during the stages of equalization and synchronization pulses in the IBV. These impulses synchronize the scanning of the electronic television beam with the arrival of the composite video signal to stabilize the video image on the screen.

Once the color distortion space is detected, the service data channel position and the associated authorization codes in the IBV can be determined. The space duration is counted (Step 237) and if the space duration is at least 7 lines (step 239), the next distortion is assumed to be on line 11 (step 241). This provides a timing pulse for detecting service data channel information on line 18. The signal is synchronized to line 11 which activates a counter for counting up to line 18 (step 243). The control data channel information on line 18 is then read (step 245). Once the data is read (step 245) the process is repeated. Typically, in pirate fastening terminals, the control data channel is compromised so that any service code is read on line 18 of the IBV, the fastening terminal is automatically authorized to begin the de-distortion. This allows the reception and unauthorized observation of distorted programs.

With reference to Figure 7, in a preferred embodiment of the present invention, the service data channel information is located on line 10 of the IBV. The piracy fixation terminals that look over the line 18 of the IBV for the service data channel and the associated authorization codes, will not detect any code, since those codes are now located on line 10 of the IBV. As a result, line 18 will be interpreted as part of an undistorted video signal. In accordance with the above, the terminal , it will not de-distinguish the signal and will form a distorted image on the television screen.

As shown more clearly in Figure 8, detection of the service data channel is initiated by looking at absence of color distortion, as described here above (step 240). Once the space is detected (step 240), the duration of the space is determined (step 242). If the duration of the detected space is at least 7 lines (step 244), it is assumed that the next distortion is on line 8 that activates a counter to count up to line 10 (step 248). The service data channel authorization codes on line 10 are then read (step 250). Once the data is read (step 250) the process is repeated.

With reference to figure 9, according to the data CDC is received by the terminal 20 (stage 252) of fixation, the processor 100 of the system loads the data in selected registers in the RAM 110 (step 253). Similarly, when the fix terminal 20 receives the data (step 254) of the service data channel, it is loaded into selected registers in RAM 110 (step 255). Then the contents of these recorders are compared (step 256). If they do not connect the contents of the two registers, the de-distortion will not be carried out. If desired, the system processor 100 may send a video and / or audio message to the subscriber explaining the reason why the de-distortion was performed and instructions are provided to the subscriber to allow de-distortion (step 260), (ie, paying to the CATV operator for the service).

In addition to the authorization information, the service data channel may also include distortion mode information. A positive link between the service data channel and the control data channel, the system processor 100 reads the remaining service data channel information to determine which distortion mode is used. It will be understood by those skilled in the art, that there are many types of de-distortion methods that are commonly used. A detailed description of the variety of de-distortion methods is outside the scope of the present invention.

In an alternative embodiment, shown in Figure 10, the system dynamically switches the place of the service data channel within the IBV between lines 10 and 18. The pirate fixing terminals seeking the service data channel on a specific line of the IBV, will be unable to locate the authorization code. In this embodiment, the distortion moves dynamically from the line 18 to a different line of the IBV, for example, the line 10. The processor 100 of the system searches for a space in the color distortion of the last horizontal scan line in the frame of video to the next distortion (step 270) and counts the duration of the space (step 272). Once it has been determined that the last space is longer than 7 lines (step 274), the processor 100 of the system determines whether the space is larger or less than ten lines (step 276). If the space is less than 10 lines, the system processor 100 assumes that the distortion is on line 8 (step 284). The system processor 100 then counts up to line 10 (step 286) and reads the service data channel information on line 10 (step 288). If the space is larger than ten lines, the system processor 100 assumes that the next distortion is on line 11. (step 278). The system processor 100 then counts up to line 18 (step 280) and reads the service data channel information on line 18 (step 282). after the data is read (steps 282 and 288) the process is repeated. In this way, the system processor 100 periodically determines the appropriate line within the IBV for which it looks at the service data channel information.

In a second embodiment, the number of specific lines within the IBV to be used as the service data channel, can be downloaded through the CDC to the fixing terminal. As a result, the system can dynamically switch the location of the service data channel based on the download of parameters on the CDC. This embodiment is shown in Figure 11. In this embodiment, the distortion moves dynamically from line 11 to a different line of the IBV as specified by the download of values on the CDC. The processor 100 of the system searches for a space in the color distortion of the last horizontal scan line in the video frame to the next distortion (step 370) and counts the duration of the space (step 372). Once it has been determined that the last spaces are more than seven lines (step 374), the system processor 100 determines whether the space is larger or less than ten lines (step 376). If the space is less than 10 lines, the processor 100 of the system loads the value previously sent via the CDC that will be used to determine which IBV line is used (step 383). The system processor 100 then counts up to the specified line (step 386) and reads the service data channel information on that line (step 388). If the space is larger than ten lines, the system processor 100 assumes that the next distortion is on line 11 (step 378). The system processor 100 then counts up to line 18 (step 380) and reads the service data channel information on line 18 (step 383). Once the data is read, the process is repeated.

In a third alternative embodiment, the specific number of lines within the IBV to be used as the service data channel, can be downloaded through the CDC to the fixing terminal. As a result, the system can dynamically switch the place of the service data channel based on the parameters downloaded over the CDC. This embodiment is shown in Figure 12. The main terminal dynamically switches the place of the service data channel within the IBV and downloads this place on the CDC. The system processor 100 searches for a space in the color distortion of the last horizontal scan line in the video frame until the next distortion (step 470) and counts the duration of the space (step 472). Once it has been determined that the last spaces are greater than seven lines (step 474), the processor 100 of the system loads the value previously sent via the CDC that will be used to determine which IBV line is used (step 476). The system processor 100 then counts up to the specified line (step 478) and reads the service data channel information on that line (step 480). Once the data is read, the process is repeated.

Although the invention has been described in part with detailed reference to certain specific embodiments, those details are intended to be instructive rather than restrictive. It will be appreciated by those skilled in the art that many variations can be made in the structure and mode of operation without departing from the spirit and scope of the invention described in the present teachings.

Claims (19)

CLAIMS.

1. - A system for preventing the de-distortion or authorization of distorted programming signals that are transmitted over a CATV communication network that includes a main terminal and a plurality of fixing terminals, the system comprises: a main terminal, comprising: means for selecting a vertical blanking interval line IBV) to insert the authorization data into the programming signal; means for inserting the authorization data within the IBV line; Y means for transmitting a location signal referred to the selected I3V line; Y a fixing terminal, comprising: means for receiving the location signal; means for determining the selected IBV line based on location signals; Y means for receiving the authorization data from within the IBV line selected to thereby allow de-distortion of the distorted programming signal.

2. - System according to claim 1, wherein the means of determination comprises: means to look for a space of separation in the color distortion within the IBV; means to measure the duration of space; means for detecting the location signal; Y means for counting a predetermined number of IBV lines of the detected location signal until the selected IBV line is reached.

3. - System according to claim 1, wherein the main terminal further comprises means for communicating a service coding map to the fixing terminal.

4. - System according to claim 3, wherein the fixing terminal further comprises means for receiving the communicated service coding map.

5. - System according to claim 4, wherein the authorization data comprises a service code authorization and wherein the enabling means comprise: means for comparing the authorization of the service code with the service code map, whereby the distorted program signals are de-distorted, if the service code authorization is within the service code map.

6. The system according to claim 5, wherein the fixing terminal further comprises means for storing the service code authorization and the service code map.

7. - System according to claim 1, wherein the location signal contains the specific address of the selected IBV line and the means of determination comprise: - means to receive the address; Y - means to access the selected IBV line.

8. - System according to claim 1, wherein the selection means alternately select lines IBV 18 and 10.

9. - System according to claim 1, wherein the claim signal comprises a distortion within the stages of equalization and synchronization of the IBV.

10. - A main terminal for use in a system to prevent the unauthorized de-distortion of distorted programming signals that are transmitted over a CATV communication network that includes a plurality of fixing terminals; Each fixing terminal comprises means for receiving a signal from the main terminal to locate a selected vertical blanking interval (IBV) line, means for determining the selected IBV line within a programming signal based on the location signal and means for receiving an authorization data from within the selected IBV line to thereby allow de-distortion of the distorted programming signal; the main terminal includes: - means for selecting the IBV line to insert the authorization data within the programming signal; means for inserting the authorization data within the IBV line; Y means for transmitting a location signal related to the IBV line.

11. - Main terminal according to claim 10, further comprising means for communicating a service coding map to the plurality of fixing terminals.

12. - Main terminal according to claim 11, wherein the transmission means comprises means for generating a pulse and inserting that pulse into the equalization and synchronization stages of the IBV as the location signal.

13. - Main terminal according to claim 11, further comprising means responsive to the selection means, to generate an address where that address comprises the location signal.

14. - A fixing terminal for use in a system for preventing the unauthorized de-distortion of distorted programming signals that are transmitted over a CATV communication network including a main terminal and a plurality of fixing terminals; the main terminal includes: - means for selecting a line of vertical bleaching interval (IBV) to insert an authorization data from a programming signal; means for inserting the authorization data within the IBV line; and means for transmitting a location signal that is related to the location of the selected IBV line; The fixing terminal comprises: means for receiving the location signal; means for determining the IBV line selected based on the location signal; Y - means to receive the authorization data from within the selected IBV line in order to allow the distortion of the distorted programming signal.

15. - The fixing terminal according to claim 14, wherein the means of determination comprise: means to look for a space of separation in the color distortion within the IBV; - means to measure the duration of the space; means for detecting the location signal; and means for counting a predetermined number of IBV lines from the detected location signal until the selected IBV line is reached.

16. - Fixing terminal according to claim 15, wherein the main terminal further comprises means for communicating a service code map to the fixation terminal and the latter further comprising means for receiving the common service code map.

17. - Fixing terminal according to claim 16 wherein the authorization data comprises a service code authorization and wherein the enabling means comprise means for comparing the authorization of the service code with the service code map to enable the de-distortion of distorted programming signals if that service code authorization is within the service code map.

18. - Fixing terminal according to claim 17, further comprising means for storing the service code authorization and the service code map.

19. - Fixing terminal according to claim 14, wherein the location signal comprises the specific direction of the selected IBV line and the determination means comprise means for receiving the address and means for accessing the selected IBV line. SUMMARY . A method and apparatus for preventing unauthorized de-distortion of cable programming includes selective relocation of the service data channel within the vertical bleaching range, thereby preventing unauthorized de-distinguishing of conventional-deactivator programs.