EP0413752A4 - In-band controller - Google Patents

In-band controller

Info

Publication number
EP0413752A4
EP0413752A4 EP19890905976 EP89905976A EP0413752A4 EP 0413752 A4 EP0413752 A4 EP 0413752A4 EP 19890905976 EP19890905976 EP 19890905976 EP 89905976 A EP89905976 A EP 89905976A EP 0413752 A4 EP0413752 A4 EP 0413752A4
Authority
EP
European Patent Office
Prior art keywords
data
generating
information
band
receiving
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.)
Withdrawn
Application number
EP19890905976
Other languages
English (en)
Other versions
EP0413752A1 (fr
Inventor
Robert O. Banker
Randolph J. Schaubs
Michael Harney
Jay C. Mcmullan, Jr.
Anthony J. Wasilewski
Gregory S. Durden
Ray T. Haman, Jr.
David Naddor
William B Thatcher, Jr.
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Scientific Atlanta LLC
Original Assignee
Scientific Atlanta LLC
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Scientific Atlanta LLC filed Critical Scientific Atlanta LLC
Publication of EP0413752A1 publication Critical patent/EP0413752A1/fr
Publication of EP0413752A4 publication Critical patent/EP0413752A4/en
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • H04N7/1675—Providing digital key or authorisation information for generation or regeneration of the scrambling sequence

Definitions

  • the present invention is directed to cable TV systems wherein video signals are sent from a headend to individual settop terminals (STT) which are typically located in any convenient television viewing area.
  • STT settop terminals
  • various levels of service are available to the set top terminals. Subscribers may choose from a wide variety of programs offered by a cable TV service. Since a cable TV service may provide many different programs, it is important to know which programs each individual set top is authorized to receive. Additionally, it is necessary to send other information from the headend to a set top for various other purposes as is well known in the art.
  • Prior systems used a separate data channel centered about 108.2 MHz to convey this information to the settop converters.
  • the individual settop terminals each had a separate tuner which was always tuned to this frequency to receive any data that may have been sent down from the headend. Since this channel is outside the band of channels that are used for sending video signals, this type of system has commonly been referred to in the art as an "out-of-band" system.
  • in-band type systems send authorization information and other information to the STT's over a channel that is used to transmit video information.
  • One problem encountered with in-band type systems is that in order for a settop terminal to receive information from a headend or other source, it must be tuned to the frequency over which the in-band information is being transmitted. Therefore, if information is sent out from a headend to all the settop terminals, only those terminals that are tuned to that frequency will receive that information at that time. This gives rise to the need for providing refresh data, or put another way, it is necessary to repetitively send out these data messages to ensure that all settop terminals will receive them.
  • an in-band controller which receives data from a system manager via a system manager interface.
  • the System Manager interface is one of the outside connections of the In-Band System. This process is responsible for gathering the data leaving the System Manager and routing this data to the appropriate modules. Data which is destined to Out-Of-Band Set Tops will be sent to the ATX Interface (another one of the outside interfaces) and the data destined to the In-Band Set Tops will be sent to the Format Translator module.
  • the System Manager Interface is also capable of relating information back to the System Manager if an inquiry of data has been requested by the System Manager. ATX Interface
  • This module is given system manager transactions and transforms them into In-Band transactions.
  • the Format Translator receives current system manager type transactions from the System Manager Interface Module. All generated In-Band transactions are then given to the Data Base Manager for storage in the data base.
  • the Database Manager is the process responsible for maintaining the Database. In order to control the flow of information into and out of the system, the Database manager has the capability of performing Add, Change, Delete, and Move (Copy) operations on any desired piece of information in its data files.
  • the term 'Database' is used to refer to a collection of data files holding data necessary for the operation of the In-Band system.
  • Each data file isdesigned to serve a specific purpose.
  • Each New List file keeps track of the most recent changes in data corresponding to its regular data file.
  • the Database manager is capable of searching for, locating, and retrieving a desired piece of information associated with a given key field (In-Band Set Top Digital Address or Channel Map Bit pattern).
  • Control/Status Manager is capable of searching for, locating, and retrieving a desired piece of information associated with a given key field (In-Band Set Top Digital Address or Channel Map Bit pattern).
  • Control/Status Manager also receives and passes back the responses that are generated by the completion of the control action requested. Control transactions can also be initiated from the Expert Operator Interface. Status inquiry transactions are also handled by this modu l e. Anytime an error occurs within the system that cannot be easily handled; this module is notified and takes an appropriate action. Startup and shutdown of all processes in the In-Band Controller are handled by this module. Refresh Controller
  • This module constantly retrieves In-Band transactions from the data base and passes them on to the In-Band Scrambler Interface.
  • the refresh controller will ensure that In-Band transactions are sent out in a manner that is consistent with the refresh configuration list.
  • This module preferably arranges the transactions so that none of the data streams are idle longer than the time it takes to sent out 3 transactions.
  • the Refresh Controller will preferably send out 120 transactions per second to the In-Band Scrambler Interface.
  • Each of the 4 data streams will receive a unique set of 30 transactions from the base of 120 sent to the interface. Every 5 seconds this module will send out 116 transactions so that each data stream only receives 29 transactions. This ensures that the scramblers send out default transactions.
  • This module is responsible for maintaining the refresh configuration list.
  • This list is an ASCII disk file which describes the relative frequency and order that In-Band transactions are sent out to the scramblers.
  • the system manager and expert operator interface can send information through the Control/Status Manager that will modify the list.
  • This module The major task of this module is to use this list to create data base retrieval requests to be used by the refresh controller.
  • the refresh controller will send these requests to the data base at set intervals. This is done so that transactions will always be available to be sent out to the Scrambler interface.
  • This module receives a list of pointers to In-Band transactions from the Refresh Controller. It takes each transaction and does a DMA transfer of the data into the custom hardware. SDLC protocol information is wrapped around the data and it is sent to scramblers over the indicated data stream. This module will block the refresh controller if it is o fered a new set of pointers before the sending of the current set is done.
  • This module also sends control transactions to the scramblers and passes the appropriate responses to the Control/Status Manager. When status information is requested, it will send back the state of the data link. BRIEF DESCRIPTION OF THE DRAWINGS
  • Figure 1 is an illustrative view of an overall system configuration for the front end of a data transmission system.
  • FIGS 2, 3, 4, and 5 are block diagrams of various configurations capable of being employed in accordance with the present invention.
  • Figure 6 is a combined flow chart/block diagram of some system components used in accordance with the present invention.
  • Figure 7 is a software module diagram of the in-band controller and associated components.
  • Figure 8 is an illustration of the reformatting that occurs in the format translator.
  • Figure 9 is a flow chart describing the operation of the in-band controller data base manager.
  • Figure 10 illustrates the configuration of the data base files and the refresh configuration list for the individual data streams.
  • Figures 11, 12, 13, 14, 15, and 16 are block diagrams illustrating various signal formats.
  • FIG. 1 shows a simplified block diagram of the in-band system.
  • the system manager 102 receives in-band transactions from the billing terminal 101 and sends in-band and ATX transactions to an in-band controller (IBC) 103.
  • IBC in-band controller
  • the IBC is responsible for formatting system manager transactions for the scrambler and loop(?) ATX transactions to the
  • the IBC has its own database.
  • the IBC stores all transactions and has the ability to perform continuous refreshes.
  • the IBC can transmit up to 4 groups of data on one serial port at 38,400 bits per second (BPS).
  • BPS bits per second
  • the four data groups or data streams as at terms can interchangeably be used or: 1) off channel data, 2) barker channel data, 3) PPV data, 4) premium channel data.
  • the off channel is tuned most of ten over a long period of time, an estimated 80% overnight.
  • the barker channel is tuned for short periods when the subscriber tries to access an unauthorized or invalid channel number, or selects a channel that is under parental control. All premium channels are assumed to be scrambled with data. All PPV/IPPV channels are assumed to be scrambled with data.
  • There is also a PPV barker channel defined which is tuned when the subscriber tries to access a PPV/IPPV channel and no preview is available.
  • Each data stream has an unique group address that is received only by scramblers with the same matching address. For instance, premium channel data may have a group address of 01, and therefore all scramblers on premium channels should have a group address of 01.
  • the IBC determines what data goes out on each data stream.
  • the scrambler amplitude modulates data onto the audio IF signal of the channel modulator.
  • Data can be fed out of the scrambler into a data inserter 105.
  • the data inserter transmits in-band data on non ⁇ crambled channels.
  • Figure 2 there is shown a block diagram of an in-band system configuration with one IBC controlling four remote headends. Since the headends are remote, the IBC's output data rate is determined by the data rate of the phone system. In this case, a 9600 baud synchronous modem is shown to transmit in-band data. As a result, rather than sending four data streams at 38,400 BPS, the IBC transmits one data stream at 9600 BPS with one group address.
  • each scrambler is given the same group address so that all scramblers at the headend receive the entire message.
  • This configuration is somewhat similar to an out-of-band system, especially if data inserters are used on all non-scrambled channels.
  • Figure 3 shows a four headend system with three IBC's located at remote headends and one IBC at the system manager site. Such a configuration may be used due to environmental conditions at a headend site.
  • Figures 2 and 3 are illustrative of configurations possible with the in-band system according to the present invention. However, it should be understood that various other configurations are possible as will become obvious to one of skill in the art.
  • the system manager is capable of transmitting information to both in- band settop terminals and out-of-band settop terminals. The choice of whether to place an IBC at the system manager site or at a headend will depend on various factors including environmental considerations (heating/cooling requirements), data transmission rate, cost and performance requirements.
  • Figures 4 and 5 show configurations similar to the configuration shown in Figures 2 and 3 respectively.
  • Figure 4 shows a preferred configuration wherein up to eight headends can be supported by a single IBC.
  • the entire population of in-band set top terminals appears to the system manager as a single headend, with a single set of headend parameters. This implies that all the out-of-band headends must also have the same headend parameters.
  • the scramblers at each headend are connected to the IBC by a 9600 BPS synchronous data link.
  • the configuration of Figure 5 shows that up to eight headends may be supported with a separate IBC for each headend with in-band settop terminals.
  • each headend may have an unique set of headend parameters, and the system manager essentially ignores the distinction between in-band and out-of-band settops.
  • the IBC for each headend may be located either at the system manager location or at the headend. Location at the headend may require environmental conditioning, but provides significant performance improvements.
  • data links may operate at 9600 BPS or at 38,400 BPS.
  • scrambler interfaces must be configured as a single data stream.
  • scrambler interfaces may be configured as either one of four data streams. It is to be understood that in these configurations the number of data streams, the number of headends and the number of IBCs is shown by way of example only and various other combinations will be readily apparent to one of skill in the art.
  • the major functions of the in-band controller involve translation of information from one format to another, storing the information, and repetitiously transmitting it to the ISTTs in the system.
  • This functionality implies at least a logical structure composed of a data input (system manager) interface, an information format translation mechanism, a data storage and retrieval mechanism, a refresh driver mechanism, and a data output (scrambler) interface.
  • certain control functions are required, primarily to maintain the configuration of the above mechanisms and in particular that of the refresh driver.
  • the system manager interface serves as the primary source of control and data for the IBC (another source is the expert operator interface).
  • the IBC accepts, for internal use, a modified set of system manager to ATX transactions.
  • the IBC is also capable of selectively phoning messages to the ATX interface.
  • the system manager interface has three layers: a physical data channel, a data link control protocol, and a de ined set of data transactions.
  • the system manager interface receives system manager transactions (step 201). After performing a validity check (step 202) in a manner known in the art, the system manager interface analyzes the transaction code (step 203). If the system manager interface determines that the transaction code is one intended for an addressed settop terminal, it then determines whether the address of the settop is within an in- band or an out-of-band range of addresses (step 204). If it is determined that the addressed transaction is intended for a settop with an address in the out-of-band address range, the system manager interface forwards the transaction to the ATX interface (step 205) which then forwards the information to the ATX in a manner that will be described below.
  • the system manager interface forwards the transaction to the information format translator (step 206). If it is determined that the transaction is an in-band transaction, the information is forwarded to the information format translator (step 206). If the transaction code is determined in step 203 to be a global transaction code the information is transmitted to both the ATX interface (step 205) and the information format translator (step 206).
  • the format translator 701 receives information including transaction codes and other data from the system manager interface. Such information is typically either global settop transactions or in- band addressed settop transactions.
  • the format translator receives this information in an out-of-band format. Its primary function is to translate this information according to stored "maps" into in-band format transactions. This step is necessary in order to provide in- band/out-of-band compatibility. That is, the system manager which issues the transactions and other information, issues them in an out- of-band format so that the information that is intended for out-of- band settops can be received by an ATX inter ace and be transmitted to the ATX and then on to the out-of-band settop terminals.
  • in-band transaction X may comprise information from field A of out-of-band transaction I and information from field F of out-of-band transaction K. It can be seen from this example, therefore, that it is possible that one in-band transaction may be made up of part of one or more out of band transactions.
  • in-band transaction Y is composed of information from field E of out-of-band transaction J and field K of out-of-band transaction K.
  • in-band transaction K is shown to be comprised of field D data from out-of-band transaction J and field J data from out-of-band transaction K.
  • these in-band transactions e.g., X, Y, Z
  • X, Y, Z are output from the format translator to the database manager 702.
  • both addressed settop terminal information and global information are received by the database manager 702 from the format translator.
  • information values are inherently linked to ISTT destinations.
  • the information is sent to its destination grouped by type.
  • Information values may or may not be valid for a certain duration of time.
  • the information type refers to the general content class of the information and is related to the particular grouping "i.e. transaction" used to send the information to a scrambler (for example, authorization information, feature matrix information, PPV load map information, etc.).
  • Type and value are related in that, within a type, information has specific values.
  • the present invention may not provide refresh at a rate seven times greater than the prior art since some transactions can not send seven addresses and for other practical considerations.
  • the present invention can provide refresh data at a much greater rate than the prior art.
  • the value is transmitted once along with six destination address. To make efficient use of the available bandwidth, this capability must be utilized. This implies that groupings of destinations with identical values (of an information type) are an important referent into the information base.
  • the time duration of information i.e. the period of validity
  • the time duration of information is a somewhat artificial construct, since all of the information must be considered ultimately changeable and therefore temporary in nature.
  • there are certain types of information which actually relate to real time and have a specific, finite time duration during which they are valid. Other information changes on an infrequent basis and may be considered relatively static. This observation points out the convenience of having some distinction within the structure of the database that classifies information with respect to notably different time durations.
  • the general operation involving the grouping, storage and retrieval of information from the information base are loosely grouped under the term database management.
  • the storage and retrieval functions are only a subset of the database management operations which also involve organizing and structuring the information, initializing the information base, and updating (i.e. additions and deletions) the information base.
  • Mechanisms must be incorporated which provide for control of these operations.
  • the drive for the control mechanism is preferably derived from a combination of interpretation of transaction content and explicit system manager control transactions. For example, when the system manager sends a new value for a specific item of information, it may be a stimulus to delete the old value and add the new.
  • Such operations require no new operations with respect to the system manager. However, if the information has the time duration or destination characteristics mentioned above, there is little or no means within current system manager transactions to convey this.
  • the database manager 702 is the process responsible for maintaining the database. In order to control the flow of information into and out of the system, the database manager has the capability of performing add, change, delete, and move (copy) operations on any desired piece of information in its data files. Preferably the database will be capable of being accessed at a minimum based on information type and destination.
  • the term database will be used to refer to a collection of data files holding data necessary for the operation of the in-band system.
  • each data file has been designed to serve a specific purpose.
  • Each new list file keeps track of the most recent changes in data corresponding to its most regular data file.
  • the database manager is capable of searching for, locating, and retrieving a desired piece of information associated with a given key field.
  • the DBM As new information is received by the data base manager (DBM), the DBM first determines if the received address is currently stored in the database (step 901). If the address is not currently stored, the DBM determines if the data is stored in the database (step 902). If the DBM determines that the data is stored then the address received with the new information is added to the addresses stored with that particular data (step 903). If this data is not currently stored, a new entry is made in the database which stores the received data and the received address (step 904).
  • the DBM determines whether Address 1 is stored in the database. If it is not, the DBM sees if DATAX is stored. If DATAX is stored, then address 1 is added to the list of addresses associated with DATAX. If DATAX is not stored, a new entry is made in the database with DATAX and Address l.
  • Address 1 it is determined by the DBM whether DATAX exists for addressl. If not, a new entry is made in the database with DATAX and Address 1. If DATAX type data exists for Address 1, the DBM determines whether the data value stored is the same as the value of the received DATAX. If yes, no change is necessary. If no, the Address 1 is removed from DATAX storage. It is then determined whether DATAX type and value data is stored in the database. If yes, Address 1 is added to DATAX. If no, a new entry is made in the data base for DATAX and Address 1.
  • the DBM determines whether there is any value for the field of that transaction stored for that address.
  • the refresh controller 704 of Figure 7 is constantly retrieving information in the form of in-band transactions and addresses from the database and passing them onto the in-band scrambler interface 706.
  • the refresh controller insures that in-band transactions are sent out in a manner that is consistent with the refresh configuration list • ⁇ hich establishes a hierarchy of data. This module also arranges the transactions so that none of the data streams are idle longer than the time it takes to send out three transactions.
  • the refresh controller will send out 120 transactions per second to the in-band scrambler interface. Each of the four data streams will receive a unique set of 30 transactions from the base of 120 sent to the inter ce. Every 5 seconds this module will send out 116 transactions so that each data stream receives only 29 transactions. This insures that the scrambler sends out default transactions.
  • Figure 10 illustrates the operation of the refresh controller with reference to the database files and the refresh configuration list.
  • database files DB1, DB2 . . .DBX as well as DBG which indicates a database for storing all global information.
  • DB1 may store information regarding transaction type 1 (T-l).
  • DB2 may store data regarding transaction type 2 (T-2).
  • T-l transaction type 1
  • T-2 transaction type 2
  • each type transaction is broken down into new data and old data. This division of data may be based on the time the information has been stored or preferably a predetermined number of transactions will be stored in the new portion of the database files and as each new transaction comes in, the oldest transaction moves out into the old portion of the database files.
  • DBG Global Data Base
  • each database file will be cylically accessed in a predetermined manner.
  • a certain hierarchy between new and old type data within each database will be provided to enable whatever information is considered the most important to the system at that time to be transmitted.
  • each data stream will be used for different data transactions and therefore each data stream may have its own refresh configuration list.
  • a hypothetical refresh configuration list for data stream 1 is shown. As shown, within each cycle for data stream 1 according to this hypothetical, 75 type 1 new transactions will be transmitted. Similarly 25 type 1 old transactions may be transmitted. The list goes on to further show that a combination of 100 type 2 new and old transactions will be transmitted. This chosen value 100 could be divided equally between the new and old type transactions or one may be given preference over the other according to the needs of the system as will be explained further below. A plead in the explanation of the example, 50 type 3 new and old transactions and 50 type 4 new and old transactions will be transmitted each cycle. Furthermore, 2 type A global transactions, 5 type B global transactions and 1 type E global transaction for example may be transmitted.
  • While the number of global transactions is indicated as being low with respect to the type 1, 2, 3 and 4 transactions, this is done by way of example only. Quite often global information is not changed as often as various other address transactions therefore it may be preferable to provide more type 1 - type X transactions than it is to provide global type information. However under certain circumstances more global information may be desired in a given cycle or over a given number of cycles. If this is the case, than this refresh configuration list could be modified in a manner that will be explained below.
  • each of databases DB2-DBX operates in a similar manner to cycle through all the information in a database or a portion of a database to provide a constant refresh to the ISTTs. So too with the information stored in the global database.
  • Each type of global information has its own pointer and each type global transaction is cycled through within the database for the globals.
  • Each cycle for each data stream is determined by the number of transactions to be transmitted.
  • data stream 1 has 308 transactions per cycle. Since the transactions are entered at approximately 30 transactions per second, the cycle time or the time it would take to cycle through the refresh configuration list for data stream 1 would be equal to the length of the list (308) divided by 30 transactions per second, the transmission rate.
  • data streams 2, 3 and 4 where each have their own refresh configuration list and the length of each list may vary.
  • the types of transactions that are sent over the different data streams depend on a number of factors.
  • One factor is the characteristic of the data stream itself.
  • Another factor may take into account the viewer statistics for that data stream.
  • Other factors that may be considered are the time of day and whether a pay-per- view or impulse pay-per-view event is authorized.
  • Figure 10 illustrates four data streams, more or less can be used. According to a preferred embodiment of the invention, there are however, four data streams used. These data streams relate to the OFF CHANNEL, the BARKER CHANNEL, the PPV CHANNELS and the PREMIUM CHANNELS. Some of the characteristics of these di ferent data streams will now be discussed.
  • the OFF and NONPREMIUM NONSCRAMBLED CHANNELS may contain addressable channel map numbers, matrix information, and PPV load map information on a rotating basis interspersed with ail globals at regular intervals.
  • the BARKER CHANNEL may typically receive recent database changes on a fast-pole basis interspersed with all global information.
  • the PREMIUM CHANNELS may be used for transactions regarding addressable channel map numbers to all addresses on a rotating basis with periodic global map definitions. This will be described further below.
  • the PPV CHANNELS would typically transmit transactions regarding addressed PPV bit maps with PPV and IPPV globals transmitted at least once per second. All data streams preferably transmit all immediate transactions when sent by the system manager.
  • this refresh configuration list may typically contain thousands of transactions. It is therefore highly desirable to transmit these transactions in as short a time as possible in the most efficient and economical manner to thereby cycle through each database at the fastest rate. By formatting the data as done in the present invention, greater efficiency is achieved.
  • earlier typical in-band transactions are transmitted with one transaction code and up to seven addresses plus data.
  • there is typically one transaction code one address in data. It can therefore be seen that with each transmission of in-band settop data according to the present invention, up to seven times as much information can be transmitted as compared with the prior art.
  • More addresses can be accessed per unit time which provides greater performance and a aster refresh.
  • the refresh configuration lists are designed to be flexible. They may be programmed into the system by a refresh configuration manager.
  • the in-band scrambler interface 706 is an interface between the in-band controller and the in-band scramblers and is composed of preferably four data streams.
  • Each of the data streams is made up of control and data transactions destined for particular sets of one or more scramblers that drive functionally related CATV channels. As described above, these data streams may typically be the OFF CHANNEL, the BARKER CHANNEL, the PREMIUM CHANNEL and the PAY-PER-VIEW CHANNELS (including IMPULSE PAY-PER-VIEW CHANNELS).
  • the interface uses a single serial data channel which carries the combined data and control transactions for all four data streams.
  • a data link control protocol provides the capability to adjust address transactions to a particular set of scramblers associated with a data stream.
  • a transport layer protocol also allows addressing messages to individual scramblers. Each data stream is allocated one fourth of the aggregate bandwidth.
  • the data transactions for the individual data streams must be interleaved, with a distribution guarantee that the scramblers receive transactions at a rate that does not require excessive amounts of buffering.
  • the interface between the in-band controller and the in- band scrambler uses shielded, twisted pair of cables as a physical interconnect medium for the data channels.
  • the physical medium exists as a single linear cable segment formed from daisy chains twisted pair interconnects between the individual scramblers.
  • a standard nine pin D-type subminiature connector is used for the in-band controller end of the data channel interconnect cable.
  • the in-band controller data channel interface always terminates, both physically and electrically, at one end of the segment.
  • a resistant terminator may be attached at the opposite end of this segment.
  • the scrambler interface data channel uses baseband synchronous signaling for data transmission. Because a single pair of conductors is used as a physical medium to connect stations in the preferred embodiment, the data and clock signals are combined using FM1 encoding.
  • the data channel uses EIA standard RS-485 voltage levels for signaling.
  • the signaling rate for the channel is 38,400 data bits per second.
  • the signal driver circuit for the data channel must be capable supplying RS-485 signal levels into a twisted pair cable terminated with a 120 ohms at each end, and a minimum of 32 RS-485 (unit loads) attached to the cable.
  • Drivers must be capable of being placed in a high impedance state when the interface is not in the active transmitter. In the high impedance state the output leakage current must be less than 100 microamps with V out in the range of +12 to -7 volts.
  • the driver circuits must present the high impedance state to the cable when in a powered down condition.
  • Signal receivers must operate over the standard RS-485 common mode voltage range specification, but with the following modified characteristics to allow up to 128 scramble units to be attached to the twisted pair: Signal sensitivity (V ⁇ +max ; V ⁇ _ max ) +/- 500 mV.
  • the interface between the in-band controller and the in-band scrambler uses the synchronous data link control (SDLC) protocol as the data link control mechanism.
  • SDLC provides the key elements required in this application; station addressability, medium access control, and error detection.
  • the IBC always functions as the SDLC "primary station” and is responsible for the commands that control the data link.
  • the in-band scramblers may function as SDLC "secondary station".
  • the format for SDLC frames is shown in Figure 11. As shown in Figure 11 there is a beginning and ending flag used to delineate the SDLC frame. After the beginning flag, there is an address which is used to designate the secondary station (data stream — scramblers) that is the destination or source for the frame.
  • the address may specify the entire set of secondary stations if all capital global address values (F, Fh) is used.
  • the control is used to indicate to the destination data stream if the information field contains control or data transactions.
  • the in ormation field contains the control and data transactions. This will be further described with respect to the transport protocol below.
  • the frame check contains the check sequence used for error detection in a manner known in the art.
  • the SDLC address preferably refers to a secondary station.
  • a frame is transmitted from the primary station (IBC) to a secondary station, then the address specifies the destination. If the frame is sent from a secondary station to the primary station, then the address identifies the source.
  • the in-band system uses the SDLC Address as a Multi-Cast Group Address.
  • Each data stream is a multi-cast group, and all stations (scramblers) that are associated with the same data stream use the same address. This is because the vast majority of transactions on a data stream or data transactions are directed to all scramblers in the data streams in parallel. Obviously, since there are four data streams, only four SDLC addresses are used in the in-band system. For control transactions, which must be directed to specific scramblers, a further layer of addressing is provided by the transport protocol as further described below.
  • the SDLC address also includes a global address GA value (F, Fh) which causes the message to be received by all stations on the data link.
  • GA value F, Fh
  • this capability is used primarily for scrambler control transactions.
  • Data frames preferably contain data transactions in the information field and are preferably directed to all stations (scramblers) in the multi-cast group (data-stream). Data frames preferably do not authorize a response from the destination.
  • the in-band system uses a MSI code (nonsequenced information) with the Pole Bit equals zero as the Control Field for a data frame.
  • Control frames are transmitted by the primary station (IBC) and contain control transactions in the information field. Control frames come in two varieties; frames which authorize and expect a response and frames which do not authorize a response.
  • IVC uses a SNRM code (set normal response code) with the pole bit equals zero for the control field of the SDLC frame.
  • the IBEC uses a SNRM code with the pole bit equals one in the control field.
  • a valid response is not received within a predetermined time period, the primary station sends the control frame with the pole bit equals zero in the control field, effectively deauthorizing all responses. The primary station may then at its option retry the poling frame.
  • Response frames are returned by a single secondary station (scrambler) in response to reception of a control frame with the pole bit equal one. Since only a single station may respond, another level of scrambler specific addressing is implied. Response frame use a NSA code (nonsequence acknowledgement) with the final bit equals one in the control field.
  • NSA code nonsequence acknowledgement
  • a secondary station Whenever a secondary station receives a valid frame of any type with the Pole/Final Bit (in the control field) equals zero, it must enter a nontransmitting state, even if it - is in the process of responding to a control field. Also, if a secondary station receives a frame with an invalid frame check sequence while it is in the process of responding to a control frame, it must enter a nontransmitting state.
  • the transport protocol is used to define a set of data and control transactions sent over the SDLC data link.
  • the transport protocol is not concerned with error control and has only limited addressing functions.
  • the primary function of the transport protocol is to define the different types of transaction messages in the data field within each type of transaction.
  • the relationship of the transport protocol transaction said data link control frame is shown in Figure 12.
  • Unaddressed or global control transactions are sent from the primary station to all scramblers in the data stream (multi-cast group) or to the global address (all scramblers).
  • Control transactions contain information that is not intended to be directly transmitted as an ISTT transaction on the in-band data channel.
  • Control transactions contain information for purposes which may include control operation of the scrambler, set time of day, set up default or "special" ISTT transactions that are buffered for later transmission and trigger transmission of a default or "special" transaction buffer.
  • Unaddressed control transactions are preferably sent in a SDLC control frame with a pole bit equals zero.
  • the format for an unaddressed (global) control transaction is shown in Figure 14.
  • the global field signals that the message is destined for all scramblers on the data stream.
  • the value of the global address is preferably always zero.
  • the command code field contains a code that identifies the control message. Allowable values are preferably from 0 to 255.
  • the data length field contains a number of bites to be transmitted in the data field. It too may have a value from 0 to 255 preferably.
  • the data field is an optional field that contains control in ormation supplemental to the control code.
  • Control transactions are sent from the primary station to an individual scrambling.
  • the SDLC address may be set to either a particular data stream (multi-cast group) or the global address (all scramblers).
  • Control transactions contain information that is not intended to be directly transmitted as an ISTT transaction on the in- band data channel. Control transactions contain information for the following purposes: control operation of the scrambler set up de ault or "special" ISTT transactions that are buffered for later transmission, and trader transmission of a default or "special" transaction buffer.
  • Addressed control transactions are preferably sent in an SDLC control frame with the pole bit equal one.
  • a response transaction may be returned to the primary station as a result of certain addressed control transactions.
  • the format for an address control transaction is shown in Figure 15.
  • Figure 15 is scene of the scrambler address field contains the physical address for the destination scrambler.
  • the value of the scrambler address is preferably in the range of 1 to 254.
  • the command code is a field which contains a code that identifies the control message.
  • the allowable values are from 0 to 255.
  • the data length field contains a number of bites to be transmitted in the data field. They may have a value of preferably from 0 to 255.
  • the data field is an optional field that contains control information supplemental to the control code.
  • Response transactions are sent from a single secondary station (scrambler) to the primary station in response to the reception of certain address control transactions.
  • the only scrambler that is authorized to send the response is the one with an address matching the address field of the addressed control transaction.
  • Response transactions are sent in a SDLC response frame with a final bit equals 1.
  • the format for a response transaction is shown in Figure 16.
  • Figure 16 shows a scrambler address field which contains a physical address for the scrambler that is the source of the response.
  • the value of the scrambler address is preferably in the range of 1 to 255.
  • the command code is a field that contains a code that identifies the addressed control transaction being responded to. Preferably allowable values are from 0 to 255.
  • the data length field contains a number of bits to be transmitted in the data field. It may preferably have a value from 0 to 255.
  • the data field is an optional field that contains response information (if any) requested by the addressed control transaction.
  • Each of the in-band scramblers transmits ISTT transactions at the nominal rate at 30 per second, corresponding to the refresh rate of the video signal being scrambled. Because the video channels are not necessarily synchronized or even frequency locked to each other, each scrambler may have a slight drift in transmission rate with respect to both other scramblers and the IBC. To compensate for the nonsynchronous system, the IBC sends transactions to each data stream at a rate somewhat slower than the minimum rate to which a channel reflect rate could drift. The scrambler therefore periodically becomes "starred" for data from the IBC.
  • the scrambler When the scrambler gets to the point that it needs to transmit another transaction, and has not receive a complete transaction from the IBC, then it inserts a "default" transaction into the in-band data. Transmitting the default transaction allows the scrambler to catch up with (an actually get ahead of) its data input requirements.
  • the default transaction is an arbitrary ISTT global, probably the "system security" transaction. It is preloaded and permanently stored in the scrambler specifically to be transmitted as a field message during the periodic IBC data underrun conditions.
  • Scramblers transmit ISTT transactions at a rate of preferably 29.97 transactions per second. Allowing for a worst case clocking mismatch between the IBC and any scrambler of .5 percent, the IBC should limit transmission of ISTT data transactions to approximately 29.82 transaction per second. By sending a maximum of 30 transactions per second for five seconds, followed by one second of sending only 29 transactions, an average rate of 29.83 transactions is achieved. Under nominal conditions this results in approximately one default transaction being sent to the scrambler every six seconds.
  • the IBC allocates 9,600 bits/sec of bandwidth to each data stream.
  • Each ISTT data transaction is 31 bytes of data plus 6 bytes of SDLC protocol overhead, plus 2 bytes of clock sync for a total of 39 bytes or 312 bits per transaction. If the IBC transmit data transactions at the above calculated average of 29.83 transactions per second, this consumes 29.83 times 312 or about 9307 bits per second. The remaining bandwidth of 293 bits per second is available for control messages. Note, however, that control messages are in no limited to using only this amount of bandwidth.
  • the data transactions for the individual data streams must be interleaved, with a distribution that guarantees that the scrambler receives transactions at a rate that does require excessive amounts of buffering.
  • the maximum burst transmit rate for any data stream should ensure that the scramblers should not have to buffer more than five data transactions under normal conditions.
  • the minimum transaction transmission rate should ensure that the scramblers do not encounter an underrun condition more frequently then is intended by the techniques discussed in the paragraphs above.
  • the expert operator interface may preferably be a standard PS/2 keyboard and video display unit as the operator console.
  • the interface is a process that is constantly running under the operating system and protects the operating system from unauthorized access.
  • Access to the expert operator interface command line functionality requires entry of a password.
  • Access to the operating system from the expert operator interface requires entry of a password.
  • passwords can only be defined using a system manager transaction. It is also preferred a log of all expert operator interface commands is written to a disk.
  • the in-band controller may be implemented according to preferred embodiment using an IBM Personal System/ ⁇ , Model 50, for processing and mass storage.
  • An IBM Model 8512, monitor is used as a console display for the expert operator interface.
  • the IBC uses one add on memory board with two megabytes of semiconductor RAM, for a total system RAM complement of three megabytes. The memory board also provides additional serial ports. Two multi-protocol data link controller interface modules and associated cables complete the system hardware requirements.
  • the in-band controller uses the Microsoft/II multi-tasking operating system.
  • the code is primarily implemented in the C language, except for where performance requirements dictate native assembly language.
  • the Microsoft Compiler and associated tools are preferably used for software development.
  • FIG. 17 illustrates in block diagram form the in-band scrambler used in accordance with the present invention.
  • An input from in-band controller is received by a in-band data board 171.
  • a digital data board 172 and analog data board 173 are also provided.
  • On the in-band board 171 there is a line interface (previously described) and an SDLC controller.
  • a microcontroller and memory are also provided on the in-band data board.
  • a digital board interface for interfacing with the digital board.
  • the overall operation of the in- band scrambler is similar to scramblers of the prior art with a couple of very noted differences.
  • One noted difference is the availability of data insertion to nonscrambled channels which are any further categorized in two ways.
  • First the scrambler is capable of scrambling any television channel and generating control signals for descrambling.
  • Second the scrambler is capable of inserting address and control information in-band in particular channels for the control of addressable settops.
  • the scrambler may be used to garble a television signal (both video and audio) for improved security in a subscription TV system that is equipped with the appropriate descramblers.
  • the descrambler is placed in the IF signal path of a video modulator equipped with a DUAL IF LOOP (DIFL) option.
  • the video may be scrambled in any " manner known in the art including sync suppression which is achieved by attenuating the VIDEO IF SIGNAL during the horizontal blinking interval, VIDEO INVERSION which is achieved by inverting the baseband video before modulation and various other scrambling methods which would be apparent to one of skill in the art.
  • the composite baseband audio is scrambled by masking the audio level by a fixed amount.
  • the audio scrambling is enabled to disable the intervals that appear to be random. These modes of scrambling are coupled with the current sync suppression and drop field scrambling. Changing the mode of scrambling is possible in intervals that appear to be random to thwart pirate boxes designed to defeat any one mode of scrambling.
  • the descrambling information is sent in-band in the audio carrier of the same channel.
  • the address and authorization information is also sent in the audio carrier of the channel.
  • the address, timing, and authorization/deauthorization information is sent as amplitude modulator pulses in the audiocarrier. Custom coding is used to make unauthorized decoding difficult.
  • audio scrambling is to preprocess the audio signal in such a way as to make it undesirable to listen to over a prolonged period of time. It is not intended to make the audio signal uncomprehensible but to make the changes in audio volume uncomfortable.
  • Each in-band scrambler has a switch selectable address in the range of 0 to 255. This is to facilitate the control of each scrambler by the system manager/in-band controller.
  • An interface is provided to facilitate defeat of presently known pirate schemes.
  • the interface aides in the inclusion of additional pirate defeat circuits in the future. Also this interface can be used to add new options to the scrambler.
  • a real time clock module is included in the in-band scrambler to send the day-time information to the settops even when the data link from the in-band controller is not functioning.
  • the in-band scramblers take all SDLC data from the all IBC, add the time, channel ID'S, four check bytes, two bits-high-count-bytes and ten scrambler control bytes, then reformat it to NTSC video timing.
  • the data is transmitted as amplitude modulating pulses on the carrier which accompanied the descrambler timing pulses.
  • An optional audio modulator will be used to put OFF CHANNEL data pulses on a nonscrambled channel.
  • the Off Channel scrambler will have a connector to supply power and the data stream to these transmitters.
  • the premium channels carry data about all ISTT's which are not authorized for this service
  • pay-per-view channels carry the pay-per-view globals which indicate which event are and are not authorized.
  • New In-Band Transactions include:
  • ATX STT Address Range Used when the ATX mode is set to Enabled. Defines a range of STT addresses that, when used as a System Manager transaction destination, cause the IBC to forward it to the ATX interface. Multiple transactions may be used to define more than one range.
  • Delete ATX STT Address Range- Deletes a range of STT addresses that has been set with the Define ATX STT Address Range transaction.
  • the frequency of phase one has no "normal" value.
  • the normal value for phase two is once (per refresh cycle).
  • the range of duration for phase one is from zero to 65 thousand transmissions.
  • the range of duration for phase two is from 256 to 32 thousand (in increments of 256), or indefinitely.
  • the frequency of special transactions is specified as the inverse ratio of the special transaction to normal transations. For example, a value of five results in the special transaction being sent once for every five normal transactions sent.
  • a duration parameter specifies the total number of times that the transaction is to be sent.
  • Default ISTT Transaction Defines the default ISTT transaction to be sent by a particular scrambler. Default transactions are sent by a scrambler when the refresh rate from the IBC falls behind the scrambler output rate. This condition occurs periodically by design.

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  • Engineering & Computer Science (AREA)
  • Computer Security & Cryptography (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Information Retrieval, Db Structures And Fs Structures Therefor (AREA)
  • Two-Way Televisions, Distribution Of Moving Picture Or The Like (AREA)
  • Iron Core Of Rotating Electric Machines (AREA)
  • Control Of Eletrric Generators (AREA)
  • Earth Drilling (AREA)

Abstract

Méthode et appareil pour permettre à un système de télévision par câble d'émettre des informations à partir d'un module de gestion de système (102), de déterminer si les informations sont destinées à un appareil monté sur téléviseur conçu pour recevoir des informations hors bande ou des informations dans la bande passante, et d'envoyer les informations au circuit approprié. Une partie des informations doivent être reformatées; c'est le rôle d'un traducteur de format (701). Les informations dans la bande passante peuvent être transmises sur un ou plusieurs flux de données. Certains types d'informations sont transmises sur un ou plusieurs flux de données, selon leur type et selon les caractéristiques des flux de données. De plus, par souci d'efficacité, des informations semblables destinées à plusieurs adresses sont regroupées dans un système de gestion de bases de données (702) de sorte que l'on peut envoyer les informations à plusieurs adresses en même temps. Des brouilleurs (104, 209) sont prévus, qui sont capables d'insérer des données dans des canaux non brouillés.
EP19890905976 1988-04-29 1989-04-28 In-band controller Withdrawn EP0413752A4 (en)

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US18848188A 1988-04-29 1988-04-29
US188481 1988-04-29

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EP (1) EP0413752A4 (fr)
JP (1) JPH03505392A (fr)
CN (1) CN1020324C (fr)
AU (1) AU626228B2 (fr)
BR (1) BR8907409A (fr)
CA (1) CA1337214C (fr)
MX (1) MX172482B (fr)
WO (1) WO1989010664A1 (fr)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5497187A (en) * 1991-11-29 1996-03-05 Scientific-Atlanta, Inc. In-band/out-of-band data transmission method and apparatus for a television system
US5477262A (en) * 1991-11-29 1995-12-19 Scientific-Altanta, Inc. Method and apparatus for providing an on-screen user interface for a subscription television terminal
DE69511665D1 (de) * 1994-12-07 1999-09-30 Koninkl Philips Electronics Nv Verfahren zur Adressierung von Benutzern in einem Fernsehsystem mit reserviertem Zugriff
US5874985A (en) * 1995-08-31 1999-02-23 Microsoft Corporation Message delivery method for interactive televideo system
US6005602A (en) * 1995-08-31 1999-12-21 Microsoft Corporation Message delivery method for interactive televideo system
US6950520B1 (en) 1999-01-26 2005-09-27 Macrovision Corporation Method and apparatus for carrying data in a video signal so that the data is not recorded
JP3676679B2 (ja) * 1999-01-26 2005-07-27 マクロビジョン・コーポレーション データが記録されないようにビデオ信号でデータを転送するための方法及び装置

Family Cites Families (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4334322A (en) * 1979-10-26 1982-06-08 E-Systems, Inc. Communication management system for providing antijam/privacy capabilities for voice radio communications
US4536791A (en) * 1980-03-31 1985-08-20 Tocom, Inc. Addressable cable television control system with video format data transmission
US4823386A (en) * 1981-04-02 1989-04-18 Texscan Corporation Addressable subscriber cable television system
US4434436A (en) * 1981-07-13 1984-02-28 Bruce Merrill Addressable premium channel obfuscation device for cable television systems
US4694490A (en) * 1981-11-03 1987-09-15 Harvey John C Signal processing apparatus and methods
US4450477A (en) * 1982-03-31 1984-05-22 Lovett Bruce E Television information system
CA1177558A (fr) * 1982-04-15 1984-11-06 Groupe Videotron Ltee. (Le) Systeme de transmission de donnees par reseau cable
EP0401873A3 (fr) * 1982-05-14 1991-09-18 Communications Patents Limited Système de communication
US4521770A (en) * 1982-08-30 1985-06-04 International Business Machines Corporation Use of inversions in the near realtime control of selected functions in interactive buffered raster displays
US4580161A (en) * 1982-11-22 1986-04-01 Pico Products, Inc. Cable television subscriber control system including addressable filters having a variable pole
US4709418A (en) * 1983-09-14 1987-11-24 British Telecommunications Public Limited Company Wideband cable network
JPS6096978A (ja) * 1983-10-31 1985-05-30 Clarion Co Ltd 有料テレビジヨンシステム
JPS60130282A (ja) * 1983-12-16 1985-07-11 Pioneer Electronic Corp Ｃａｔｖにおけるデ−タ伝送方式
US4802220A (en) * 1985-03-20 1989-01-31 American Telephone And Telegraph Company, At&T Bell Laboratories Method and apparatus for multi-channel communication security
US4716588A (en) * 1985-10-29 1987-12-29 Payview Limited Addressable subscription television system having multiple scrambling modes
US4710955A (en) * 1985-11-25 1987-12-01 General Instrument Corporation Cable television system with two-way telephone communication path
US4817144A (en) * 1987-03-12 1989-03-28 Zenith Electronics Corporation Secure TV scrambling system using framing code switching

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
No relevant documents disclosed *
See also references of WO8910664A1 *

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Publication number Publication date
AU3562589A (en) 1989-11-24
MX172482B (es) 1993-12-17
EP0413752A1 (fr) 1991-02-27
CN1020324C (zh) 1993-04-14
CA1337214C (fr) 1995-10-03
AU626228B2 (en) 1992-07-23
JPH03505392A (ja) 1991-11-21
BR8907409A (pt) 1991-04-16
WO1989010664A1 (fr) 1989-11-02
CN1040476A (zh) 1990-03-14

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