FR2560473A1 - METHOD AND DEVICE FOR DIFFUSION OF SIGNALS BY SUBSCRIPTION - Google Patents

Abstract

THE INVENTION RELATES TO THE TECHNIQUES FOR BROADCASTING SIGNALS TO A GROUP OF SUBSCRIBERS. THE DEVICE OF THE INVENTION PROVIDES A MEANS FOR USING AN ADS DISTRIBUTION SYSTEM 21 WHICH IS CURRENTLY USED IN TELECOMMUNICATION NETWORKS 20, TO ALLOW SUBSCRIBERS TO ORDER TELEVISION OR OTHER SIGNALS 23, TRANSMIT BY TRANSMISSION. A SUBSCRIBER 18 EQUIPMENT INTENDED FOR SIGNAL DECODING IS CONNECTED TO THE TELECOMMUNICATION NETWORK 20 BY A NORMAL TELEPHONE LINE 28. APPLICATIONS TO SUBSCRIPTION TELEVISION BROADCASTING SYSTEMS.

Description

The present invention relates to the distribution

  signals, in particular radio or television signals.

  in such a way that it is possible to exercise control over their use, as is the case with so-called "pay television". While commercially broadcast television signals could generally be received by anyone wishing to receive them, there are other signals that can only be received by members of a small group of subscribers. The subscriber sometimes

  choice to order or not to control a particular signal

  for a given period. If he actually commands

  the signal and if it receives it, it becomes a "user"

  Although there may be a number of variants in signal distribution systems with the possibility of

  The following description applies to a typical system

  than. The signal of an emission is generated by an entity

  "producer" of programs and is transferred to a

  tributor who offers it to subscribers, by cable, on the

  base of orders made by subscribers. The broadcast signal

  sion is coded. Its use is controlled by selectively making available to subscribers a key for the decoding of this signal. Subscriber equipment is provided to the subscriber that includes the decoding hardware and decodes the signal of a channel selected for the receiving equipment. The subscriber equipment may also require to receive decoding key information before it can

perform the decoding.

  The subscriber can control the transmission signal of

  annually, monthly or shorter term. The com

  Mande can also be broadcast. A

  control unit located at the remote location can

  provide the subscriber equipment with a decoding key for specific programs that have been ordered. We find

  example, the description of systems of this type in the

  United States vets the following: 4,008,369, 4,115,807, 4,325,078,

4,358,201 and 4,369,462.

  Collection of statistical information

  about the number of users, that is the number of

  for a program and the identities of subscribers who have ordered a program, for billing purposes, have some difficulties with subscription systems

  current. If billing is not done sufficiently

  frequently, the number of subscriber accounts for which recovery is impossible may become too high to be acceptable. On the contrary, if billing is done too often, the cost of shipping bills becomes excessive. For billing purposes and for other purposes, it would be desirable to have an indication

  the actual number of users for a given program.

  Signal theft is another difficulty encountered with current subscription systems. It is often possible for subscribers who have not ordered a broadcast signal or to non-subscribers who have access to the encoded signal to find a way to decode the signal independently or to act fraudulently on

  the control unit to provide the key to deco-

  to the subscriber equipment. This can not normally be detected and it is thought that it is currently

  a relatively large and persistent problem.

  Another problem that affects subsystem systems

  the current issue with issue-by-issue control, is their inability to provide program producers with

  an independent means of measuring the audience of

  in which they have a financial interest.

  The last, and perhaps most important, issue of emission control systems,

  is that which results from the purchase "by impulse". It appears

  to be in human nature that subscribers decide to

  to control an emission signal shortly before

  sion of the program in question. This may saturate

  equipment to accept and record transmission orders when the proposed program is

  of great interest to a large number of subscribers. The capacity

  city of the order taking equipment then becomes a

  constraint on the sales of the emission signal.

  In accordance with the original method and device of the invention, a desired transmission signal from a subscriber is automatically controlled by a subscriber equipment which has received a control command under the influence of the subscriber's operation. a control switch on the equipment. The order is made through

  a telephone line. In response to the order, the equi-

  subscriber receives the same telephone line with decoding key information and records it in a

  memory. The coded transmission signal that has been ordered

  mine with it auxiliary signals comprising an order signal which activates the decoding means in the equipment to use the key information for decoding the signal during the duration of the transmission. The subscriber equipment according to the invention comprises means for automatically transmitting a transmission command by a

  telephone line and means to record the information

  the decoding key received by the telephone line

  response to the command. It also includes means of

  arranged to receive order signals accompanying a transmission signal, to activate the signal decoding means

  resignation. The equipment may also include a device

  display for other information that is provided

  with the key information or by the auxiliary signal.

  The invention will be better understood on reading the

  description that follows of an embodiment and in

  referring to the attached drawings in which:

  Figure 1 is a block diagram, partially

  in pictorial form, illustrating the interaction of various elements of a subscription

  according to a preferred embodiment of the invention.

  FIG. 2 is a front view, in elevation and in perspective, of an embodiment of a subscriber equipment of the system of FIG. 1, for the decoding of the transmission signal, intended to be used by the receiver

with which he is associated.

  FIG. 3 is a perspective view, from the rear and in elevation of the subscriber equipment of the

figure 2.

  Figure 4 is a graphical representation

  schematic of the information contained in a key to deco-

  which is issued to the subscriber equipment of the figures

1-3, in response to an order.

  FIG. 5 is a graphic representation of

  managed frequencies of the orders issued, in comparison with the orders satisfied for transmission signals

of the system of Figure 1.

  Figure 6 is a functional block diagram

  circuits of the subscriber equipment of Figures 2 and 3.

  The subscription television system with

  transmission emission, 10, shown in FIG.

  drawings, is an example of a system in accordance with the

  vention. In the system 10, a program producer 12, a television network 14, a broadcast station 16 and a transmission signal control and decoding subscriber equipment 18 are all interconnected by means of a network of transmitters. telecommunication 20. The telecommunications network 20 includes an ad distribution system 21, which is now commonly referred to in the United States as a "5900 Service", as it is currently in the United States. Accessing this service usually requires dialing "900" for the first three digits of the phone number that is associated with the particular ad service being considered. The ad distribution system 21 is controlled by a registered program control system 22. The apparatus necessary to introduce such a service into a telephone network, as well as the details of its operation, are well known in the field of telephony and are

  described, for example, in the Bell System Technical Jour-

  July-August 1981, Vol. 60, No. 6, part 2. An ad distribution system of this type is capable of accepting a large number of incoming order calls

  for various ad services, and auto-reply

  individual calls with a predetermined message.

  In the usual applications of "Service 900", it is very common that the message to be delivered to

  applicants is not registered in any equipment

  telephone company, but instead provided directly from the premises of the creator of the message. The telephone company's equipment then creates as many copies of the message signal as it needs to satisfy the instantaneous number of callers who wish to receive the message. Because of this system of direct distribution of messages, from 1 to N, the creator of the

  The message has full control of the message signal.

  ge and it can, for example, provide repetitions of a

  brief amessage or a live broadcast. This message

  can be in the form of a voice announcement or a

data information.

  The same ad system also includes

  means of generating statistical information relating to

  users, for example by registering the number of orders and types of orders as and when

  receipt thereof, and it also includes a billing system

  ration to automatically correlate the calls with the identity of the lines of the telephone service that were used to make the order call. This allows the service amount to be billed in the same manner as the billing for the telephone service and in some cases this means that the amount due for the ordering of a service

  announcement can be added as a section

  on the telephone bill. Because such procedures are now well known and widely

  used, they will not be described here in more detail

  except for the advantages that they can

  bring because of their use in the system 10.

  The interconnections between the program producer 12, the television network 14, the broadcasting station 16 and the subscriber equipment 18 via the telecommunication network 20 are accomplished by means

  any of the common signal transmission means

  used, or combinations thereof, which are suitable for the type of signal transmitted. Companies of

  currently offer a wide range of

  services for connections between producers, television networks and radio stations.

  diffusion. They also offer a telephone service line.

  phonic, usually in the form of wires, for subscribers who have telephone service. The nature of the interconnection equipment to be used in connection with the invention will therefore not be described in detail here except with regard to the advantages that this equipment can bring as a result of its use.

in the system 10.

  It is assumed that the producer 12 is the original source of the signal to be proposed as a transmission signal intended to be viewed by the subscribers on their own receiving equipment. The transmission signal from the producer 12 is directed to the network 14 which determines the subsequent distribution of this signal to various broadcasting stations which are geographically distributed to

  allow wide dissemination of the transmission signal. The sta-

  broadcast 16 transmit the transmission signal to

  subscriber equipment 18 of each subscriber over the air

  cable, direct broadcast satellite or

  another suitable medium for transmitting

  if we. In the system 10 of FIG. 1, the transmission signal transmission medium is represented by electromagnetic radiation 23. The latter is picked up by an antenna 24 at the subscriber's location and is routed to the subscriber. Subscriber equipment 18 26. In some applications, such as in the case of direct broadcast satellite or cable television,

  signal conversion equipment, filters, amplifiers,

  or others may be inserted between the antenna

  24 and subscriber equipment 18, with appropriate drivers

  required 26 to connect such devices. The equipment

  subscriber 18 may receive several different transmission signals

  associated with different frequency channels. One or more of these signals may be in coded form, while others may not be coded and may therefore be

  available for the general public, without payment.

  Subscriber equipment 18 is connected to the network

  telecommunication 20 by telephone lines 28.

  it is not necessary that these lines 28 be dedicated lines. So, they do not need to be

  used exclusively for the operation of the team-

  subscriber 18, and they may instead be the usual telephone lines of a dwelling

  feature comprising only one telephone service

  than. This is a particularly important aspect of

  because the knowledge that the telephone company

  The subscriber's telephone line number allows for proper billing without the need to identify subscriber equipment 18 itself. The subscriber equipment 18 is connected to the television receiver 30 of the subscriber by signal conductors 32. A feature of the system 10 consists of

  that the transmission signals emitted by the transmission medium

  Transmit signal 23 is accompanied by auxiliary signals carried during the scan sweep interval of the signal. Techniques for conveying information during the scan return interval of a television signal are well known in the art

  television broadcasting. Auxiliary signals

  take control and display signals in the form of

  me a slow digital information.

  Figures 2 and 3 show in more detail

  Figure 2 shows the front of the equipment 18. At the left end is a power (on-off) switch 36 which can control the power supply. of the subscriber equipment 18 alone or may also control the power supply to the receiver 34. To the right of the switch 36 is a command request button 38, through which the subscriber can command the equipment 18 to order a desired broadcast. Next to this button is a channel select switch

  40. An electronic alphanumeric display panel rec-

  tangular 42 is provided for displaying information

  transmission and transmission control. On one side of the team-

  18 is a mechanical lock 44 which allows

  switch off the equipment 18 to prevent

unauthorized use.

  Fig. 3 shows the back of the equipment 18 with various electrical connection means including transmit signal output terminals 46 through which the transmit signal passes to the receiver 34, signal input terminals 48 by which the signals picked up by the antenna 24 are received via the conductors 26, an auxiliary power supply receptacle 50 through which the equipment 18 can control the power supply of the

  receiving equipment, a power input connector,

  tation 52 by which the energy of the sector is applied to the equipment 18, and a pair of telephone jacks 54,

  56. Jack 56 is suitable for an extension telephone

  mentary. The jack 54 is directly connected to a telephone network. In the operation of the system 10, it is first assumed that the equipment 18 is powered. The auxiliary signals will provide broadcast information that will appear on the display panel 42 to provide information to the subscriber regarding the existence of

  and the time of a proposed show. The panel can also

  indicate the cost to the subscriber. However, for this information to appear on the display panel 42, it is necessary that the channel select switch be in the appropriate position to receive the signal channel that is associated with the proposed program. Such display information can be incorporated into the transmission signals of each of the available channels, so that the subscriber can select this display information as desired, by appropriately positioning

  the channel selection switch 40.

  If the subscriber wishes to order a program that is proposed, it is sufficient to press the request button of

  command 38 during the time interval specified by the

  displayed training. This will trigger in the equipment 18 a transmission control sequence under the effect of which -5 an automatic call will then be sent to the ad distribution system 21 of the telecommunications network 20. The call will be triggered by a appropriate order message

  incorporated in the auxiliary signal. The distribution system

  Announcement 21 will recognize, by the telephone number that has been called by the equipment 18, that this call requires

  a particular transmission control response. It does

  will then kill this response by automatically connecting the call from the equipment 18 to an announcement in the form of a slow voiceband data signal which

contains a decoding key.

  Figure 4 schematically shows an example of a decoding key. This consists of a data message 58, repeated continuously, which has a duration of

  3 seconds. We choose the length to ensure compatibility

  with current telephone network standards, to validate the call. The key information is in the form of a number of coded digital values of

  in a numerical way that can be used to define the

  cient of a signal filter. It should be noted that the amount of information that is ordinarily required

  for decoding can be transmitted in a fraction only

  During the three-second interval, there is a considerable amount of time that can be used to transmit other information to the equipment 18. This information may be display information or related information.

  at the control of the operation of the equipment 18, similar to

  to that contained in the auxiliary signal.

  When equipment 18 receives information from

  decoding key, it saves the key in an associated memory.

  the channel of the selected program. The equipment 18 is now ready to decode the transmission signal, when it receives the command at the moment when this signal will be applied to it. At the beginning of the broadcast, the control signals that are contained in the auxiliary signal provided with

  the transmission will give the decoding circuit the order of

  active nir The activation instructions will continue for the duration of the broadcast. A subsequent broadcast will have a

  different coding format and will therefore require a different key

  you. Thus, although the subsequent transmission also carries with it the control signals intended to activate the decoding circuit, this will be insufficient for the decoding process, because the equipment 18 will not have in its own right.

  memory the key information needed for decoding.

  There are a large number of coding methods known in the art that could easily be used with the system 10. The particular method that is chosen depends on the complexity chosen for the equipment 18 and for the coding equipment, as well as the nature of the particular signal to be transmitted. The preferred type of coding for use with the system 10 is a type in which a digitally encoded key can be used to correctly set the coefficients of a signal filter.

  of the decoding circuit in the equipment 18, for the decoding of

  ge. Specialists in the coding of television signals

  are familiar with various coding techniques of this type and can

  can easily be adapted for the system 10. It is not

  ra here not here the details of structure of the circuits of

  decoding that are necessary for this operation.

  The transmission control request device of

  the equipment 18 includes a memory in which an instru-

  Transmission request request generation from the subscriber is retained until the equipment 18 receives an appropriate decoding key when calling the advertisement delivery system. Any other result

  of the call, as a signal of occupation, leads the team-

  18 store the broadcast command request instruction. This device further comprises means sensitive to the control signals which form part of the auxiliary signals conveyed with the transmission signal, and

  which determines that the call is triggered

  given a particular time interval, determined by a

  overload detection equipment of the distribution system

  ads. These features, described above, are particularly advantageous in situations where there is a high level of "pulse-on" control. FIG. 5 shows graphically the problems that appear in the presence of an impulse control of transmission signals. Baseline 60 represents the flow of time to the instant of the start of the transmit signal. The ordinate represents the number of events corresponding to transmission commands. Curve 62 shows

  the number of orders made over time by the subscribers

  that have operated the transmit control request switch 38 on their equipment.

  curve 64 shows the number of commands to which the system

  ad distribution was able to respond. It can be seen that during the short interval that separates the end

  of a normal broadcast and the start of the broadcast signal

  In this case, there is an overload condition of the ad distribution system. As discussed above,

  equipment 18 will continue to attempt to transmit the

  if it encounters a busy signal in such an overload condition. However, the final result can

  be that, in a situation of severe overload, information

  The decoding key is not provided at the time the broadcast is to begin. This would charge the subscriber the entire program, while he has not been able to decode it from the beginning. To avoid such a state of affairs, the transmission signal can be initially transmitted with a first coding. Appropriate control signals provided by auxiliary signals transmitted with the transmission signal will enable any subscriber equipment 18 to decode the transmission signal by the use of decoding key information which is already available for the transmission of the transmission signal. 18, either because it was wired in this equipment, or because it was supplied at a previous time, or because it is provided in coincidence with the control signal, to switch the equipment in that equipment first decoding state. This state of decoding of the equipment 18 will be called the "internal key" state. It is also possible to use the command and data information.

  which is contained in the auxiliary signal for

  equipment 18 in a state in which the circuit of

  decoding is not used, such as when the broadcast signal is

  sion is not coded because it is intended that it be

  tribute to the entire public. This will be called the state of

"turn off the key".

  The probability of overloading the command receiving equipment can be reduced by distributing the sending control calls of the subscriber equipment into groups 18. The groups would be determined by internal identifiers. For example, slow control and data signals accompanying the transmission signal may include transmit control call activation commands for the equipment in three different formats that are sufficiently spaced in time to allow to accept the level of commands that is expected for the broadcast. The subscriber equipment would be equipped with corresponding filters, in groups, so that a given call activation order activates only

  the group which includes a passing filter for the signal con-

  flabbergasted. The others would remain in a condition of waiting

  until they are activated by their respective control signals. In this way, the catching ability

  The system controls are used very efficiently.

  It is furthermore possible to adjust the time allocated for the transmission command calls of the equipment groups 18 during the order taking, since statistical information concerning

  users, kept by the control system

recorded gram 22.

  There are therefore three signal reception states of the equipment 18. The first is the key off state, in which the decoding circuit is inactive and the transmission signal is transmitted without modification to the receiver. 34. The second is the internal key state, in which the equipment 18 decodes the encoded transmission signal using internally available decoding key information. As described above, this state can be used if the transmit command request button 38 has been pressed and the key information has not been supplied at the start of the transmission. The third state is the state

  using a controlled key, in which the broadcast signal

  is decoded using the key information provided in response to a command call for the particular issue.

  ree. Figure 6 is a functional block diagram

  of the subscriber equipment 18. The sub-assemblies A-L

  felt on the left side of the equipment concern in a

  the reception and decoding of the tele-

  vision, while the N-Z subsets on the right side are largely concerned with the telephone connection and the reception and processing of the decoding key and

  associated messages. Those skilled in the art can easily imitate

  manage the functional details of the subsets.

  A subsystem of power supply A, under the control

  of the switch 36, distributes the energy throughout the equipment. Subassemblies B, C and D provide conventional television receiver functions which are tuning, intermediate frequency and video amplification and automatic gain control. The subset B is an electronic tuner or tuner; it indirectly receives the channel change information, via the controller M, instead of receiving it directly from the channel selector 40, as this

  would be the case with a mechanical tuner.

  The receiver subsystem E receives the signal from

  output of the amplifier C and it extracts signals

  those of the scan return interval lines which include pay-TV header signals. These auxiliary signals are assembled into control messages and are then transmitted to the buffer circuit

  message J, to be used by the subset

  The control message receiver E reports parity and message format errors to the weak station detector F, which measures both the output level of the automatic gain control (AGC) and the rate of change. message error, to determine whether a low station condition should be signaled to the controller M. The main function of the tuner B and the amplifier C is to prepare the television signal that appears at the input 48 for the decoding circuit ,

  in the form of a descrambler G. Two sets of conductive

  input drivers control the operation of the descrambling

  their G: firstly those coming from interrup-

  state control units, positioned by the subset K; and secondly those that carry the decoding key input signals that are provided by the subset of

  key supply L. The circuits contained in the

  jammer G are placed under conditions corresponding to the deactivation or use of the descrambling logic, under the control of an order from the state control switches K. The descrambler

  G is restored to the off state of the key

* that time it is not powered by the subset A.

  The decoding key is applied to the descrambling

  their G to operate in the correct mode and with the correct time characteristics to decode the television signal. The decoded signal is applied to the RF modulator subsystem H to be converted into a signal suitable for use by the television receiver

  of the subscriber. A setting 47 is provided for the sub-

  set H to set the output channel on VHF channel 3 or 4, typically. A fraction of the decoded signal is also applied to an optional subset I that separates and amplifies stereophonic sound output signals and applies these signals to the optional outputs 57 and 58 for connection to the subscriber's sound system. In addition, the output signal of the descrambler G is applied in part to the control message receiver E in order to receive coded control messages and thereby test the operation of the descrambler G. The controller M receives signals corresponding to condition changes in the equipment 18, and then reacts by taking the appropriate action, as determined by its associated programs. As

  For example, the controller M can be alerted of the arrival of a message.

  by the subset J; this message should be a text message. The controller M then uses its programs

  display to convert the message data to

  Displayed that are sent to the subset

  N Display Attack Subsystem.

  chage N then creates the appropriate text on the external display panel 42 and also applies it to the access

  auxiliary data output 43.

  The controller M notes the position of the lock 44 each time the subscriber actuates the command request button 38 or the channel selection switch 40.

  can thus use the lock 44 to prevent

  derive signals, that is, equipment 18 must be "unlocked" to be

  possible to control transmission signals. In a similar way

  the lock 44 can be used to allow or not

  not allow to watch programs on certain channels.

  The subscriber validates the desired channels by placing the lock 44 in a "channel enable" position and using the channel select switch 40. The controller M then controls the display panel 42 to indicate the channel numbers and their validated / invalidated state under the

  dependence of selections made by the subscriber.

  The switch controller and switch detector P and the digit transmission subassembly 0 provide the

  automatic numbering function for the equipment 18.

  The subset P determines and controls the busy / free state of the subscriber's telephone line, to enable the equipment 18 to make telephone calls without

  interrupt the normal use of the phone. The sub

  set 0 outputs the digits of the desired telephone number.

  The data carrier detector Q, the key and message buffer R and the message and key receiver S together form the receiving part of a slow modem. After issuing a request for a decoding key, the controller M waits for a signal from the data carrier detector Q and indicating that the call has actually reached the intended destination. If this signal is not received during the appropriate time interval, set by a control message and measured by the timer subset T, the controller M aborts the call attempt. If the call was successful, the controller M

  waiting for the key and other messages to be delivered through

  of the subsets S and R. If the subset S does not

  receive an appropriate key signal, the controller M con-

  I'm sorry again that the call was unsuccessful.

  The controller M, the memory W and the clock T are preferably powered by a backup power source

  (battery) V. Backup energy is applied to the control

  their M by a U power test subassembly that alerts the controller of a low voltage condition of the battery. The energy to recharge the battery is provided by the subset A when the equipment 18 is in the ON state, and by the subset P when it is in the OFF state. The subset of memory W fills at once

  RAM and ROM functions. The sub

  set of program X contains the programs and

  permanent products, such as a serial number of equipment,

  necessary for the operation of the equipment.

  common data set Y records trans-

  sitoires, as a busy / free state of the switch hook, that can be considered as used in common by all

  broadcast channels. This is to be opposed to the

  stored in the partitioned storage area Z, such as the telephone number to be called to order a future program. The controller M affects areas in the

  memory Z on the basis of the appearance of control messages

  of in the message buffer J every time

  the subscriber makes a change to the channel selector 40.

  All data relating to program commands are kept separate by channel in the memory Z. The equipment 18 preferably assigns a section

  of memory Z to each channel that is validated and that transmits

  puts a control signal, when this equipment notes the presence of both the control signal and the validation signal. There is no intercommunication between broadcast stations inside the memory Z. In addition, the memory areas that are assigned to each channel are only accessible to commands received in the memory.

  auxiliary signal or via the tele-

sound. -

General considerations

  The key information that is provided by the tele-

  phone itself can be coded. For example,

  kill this by hiding the key data inside a much longer data signal which consists largely of meaningless information, in

  using a digital substitution technique or using

  reading any arithmetic operation that is

  sible. The key would be decoded or simply extracted from the

  non-significant training by the use of other

  available for the descrambler G before or during

  the program that has been commissioned. Such data

  belong to any of the following categories

  are: (1) data transmitted in the control signal in coincidence with the key data (a

  comparison "good / bad" with a configura-

  order or another decoding signal.

  DAGE); (2) data as in (1), but transmitted via a control signal at an earlier or later time; (3) permanently recorded data

  in the equipment (such as an identification number

  protected term, the term "protected" means that this number is unknown to the subscriber);

  (4) data previously or

  by telephone, in the same phone call or in a different call, such as

  for a technique of first payment / pay-

  final payment, or for a sliding scale rate for large users; or,

  (5) a combination of these methods.

  An important advantage of this system lies in the possibility

  for each television network to create a desired variant of the principle of key distribution using

  techniques such as those described here. This is possible

  B sible because each network provides its own signals

  command and its own telephone signals and can

  use these signals to specify the sequences of operations

  accomplished by the descrambler G, in real time.

  This system can also be advantageous for networks that do not choose to broadcast their programs in a paid way. These networks can still present messages on the equipment 18 if the transmission signal carries the appropriate auxiliary signals containing

display messages.

  You can use the application procedure

  transmission of this system to interrogate subscribers for their answers to questions appearing on the display panel 42 of the equipment 18 or which are

  presented in a program watched by subscribers.

  The system 10 above is a specific example of the present invention. It is evident from the various observations made below that one skilled in the art can make many modifications to the system without departing from the scope of the invention. The transmission signal is not limited to a signal of a particular frequency or a signal carried by a particular medium. He can be

  a television, radio or other frequency signal.

  The encoding technique may take any suitable form suitable for transmitting a separate decoding key, in the form of a message transmitted from

  electronically that can be registered in the team-

  subscriber. The transmission signal must only be accompanied by a control signal intended to activate the

  decoding. The display data signal is optional.

  The control signal which accompanies the transmission signal may be transmitted to the subscriber equipment in any suitable form, provided that it has an appropriate time relationship with the transmission signal, to allow the transmission of the transmission signal. activation of the decoding simultaneously at the beginning of the emission. Although it is convenient to route the control signal through the same channel as the transmit signal,

  this is not essential, and we can provide the signal of com-

  other means of transmission, if it is preferable

  corn. The ad mass distribution system of the

  system 10 is described because such a system is presently

  service in the United States telephone network.

  Any system of a telecommunication network which is capable of

  to answer with a decoding key to a call for

  of emission, and to do so in a sufficiently short time to satisfy to an acceptable degree the demand of the subscribers with regard to the transmission commands, would be suitable for use. For example, an electronically programmable PBX can be adapted electronically to

such function.

  Manual interlock on subscriber equipment can prevent issuance of program orders without

  to stop watching a program and without canceling

  already transmitted. In certain circumstances, he may

  it is desirable to provide the subscriber equipment with a

  me to remove the possibility of issuing program orders, if the equipment detects that the transmission signal from the transmission channel is too weak to give an acceptable presentation of the program or would be susceptible

  to reveal errors in the control signals.

  The equipment may also include a memory for recording the times during which an unsatisfactory signal is received. The television network can automatically access this information at a later time and use it to define the conditions under which future orders may be issued, or possibly

to make a refund.

  The information intended for display may appear

  be on the television screen in the "legend" area in

  top or bottom of the screen, instead of appearing on the

  subscriber. The display on the equipment or otherwise outside of the television picture can take various forms. It may for example be performed by a printing mechanism connected to the subscriber equipment in the form of a slave unit.

  The memory of the subscriber equipment is preferably

  type that keeps the recorded information in the absence of external energy. This allows decode key information to be introduced into a subscriber's equipment and then transported to another location to receive the broadcast. This would allow the rental of such equipment already provided with key information for a

duration or a given emission.

  It is possible to design the connection of the subscriber equipment to the telephone network so that it is wireless. In addition, the equipment can be equipped with a handset and a numbering mechanism for

  be used as a telephone.

  It goes without saying that many modifications can be made to the device and method described

  and represented without departing from the scope of the invention.

Claims (21)

  An electronic device of the type comprising: a transmission receiver for receiving a transmission signal in coded form from a signal transmission medium; a decoder for selectively decoding the   transmission signal and transmitting it to a receiver; a con-   controller for controlling the activation of the decoder; and subscriber equipment that can be externally actuated to receive a co. emission control; characterized in   what it includes: a system for recording   emission control; a switch connected to a telephone line to automatically transmit an order   to a service number, in response to the transmission command   if we; and a memory for automatically receiving and recording decoding information provided via the telephone line, in response to the control of the transmission, to enable the controller to trigger decoding, which controller is functionally dependent of order that are provided with the transmission signals.   2. Device according to claim 1, characterized   in that it comprises a decoder which operates under the control of a control signal which is also provided by the transmission signal transmission medium, for confirm the switch.   3. Device according to claim 2, characterized   in that it comprises a display device for displaying information provided by the control signal, to communicate to the user information concerning   emissions or other type of information.   4. Device according to claim 3, characterized   in that it comprises a channel selector for selecting from among different channels of transmission signals provided by the signal transmission medium 3, 'esso.11 ::; c; rr-   5. Device according to claim 4, characterized   an auxiliary signal for selectively allowing an uncoded transmission signal not to pass through them decoding means.   6. Device according to claim 5, characterized in that it comprises an internal key decoder capable   to decode certain predefined transmit signal channels   originated from incoming transmission signals.   7. Device according to claim 6, characterized   in that it comprises separately transmitting transmission control means, transmit control recording means, decoding key recording means, and decoding activation means individually associated with each channel and capable of having at least two different telephone numbers for transmission program orders.   8. Device according to claim 7, characterized   in that it comprises a detector for preventing the control of an emission signal which is detected as being   too weak to be properly received.   9. Device according to claim 8, characterized   in that the display device is alphanumeric.   10. Method for controlling the decoding of a signal   coded, characterized by the operations of receiving   see a request for a transmission order from an equi-   subscriber by a telephone line, and to respond to this request by referring to this line information from   decoding key, for registration in that equi-   without the need for subscriber equipment to identify itself trust. -   11. Process according to claim 10, characterized   in that the response includes transmitting   to the equipment, along with information from decoding key.   12. The process according to claim 11, characterized   in that the response comprises transmitting data signals to the equipment, along with the decoding key information, the data signals being adapted for use by a display device at the location of the subscriber. Method according to claim 10, characterized in that first control signals are transmitted to the subscriber equipment, simultaneously with the coded signal, for   validate the decoding device of the subscriber equipment.   Method according to claim 13, characterized in that second control signals are transmitted to the subscriber equipment, independently of the response signal, to control the validation of the transmission equipment.   emission control of the equipment.   15. The method according to claim 14, characterized in that the second control signals accompany the   encoded signals on the same transmission medium.   Method according to claim 14, characterized in that the display information is transmitted in the company of at least one of the first and second control signals,   for display at the subscriber's location.   A system for controlling the access of a subscriber to a signal, characterized in that it comprises: means for coding the signal and transmitting it to a subscriber decoding equipment; telephone means   connected to the subscriber equipment and designed to receive   see transmission command calls from the equi-   and respond to program orders by transmitting   to equipment, by telephone means, information   key that is necessary for the equipment to decode   the signal, if this equipment is validated; and means of   intended to transmit to the equipment a first communication signal   with the transmission signal, this first control signal being designed to validate the equipment   for decoding the transmission signal.   18. System according to claim 17, characterized in that it comprises means for transmitting second control signals to the equipment, in the company of   key information, by telephone means.   19. System according to claim 18, characterized   in that it includes means for issuing data   display in the company of at least one of the first and second control signals.   20. System according to claim 17, characterized in that the first control signals comprise signals intended to validate the transmission command calls. subscriber equipment.   21. System according to claim 20, characterized in that it comprises means that react to the number   of transmission command calls received from the   subscribers by determining the validation of the transmission command calls of the remaining subscriber   means of the first control signals.