APPARATUS AND METHOD FOR CONTROLLING A RECORDING MACHINE

Abstract: A method of controlling a recording machine, incorporating a tuner, in order to effect the recording of a programme included among transmissions of a number of programmes, the method comprising the following steps: transmitting information about programmes in a transmission, receiving the transmission and passing it to the recording machine, passing the transmission through the tuner of the recording machine and passing a baseband output signal including the programme information from the recording machine to an apparatus for controlling the recording machine, detecting the programme information in the baseband output signal from the recording machine by means of the apparatus for controlling the recording machine, sending a start signal from the control apparatus to the recording machine via a wireless command link to start the machine recording, the timing of the start signal being in accordance with the programme information detected, and sending a stop signal from the control apparatus to the recording machine via the wireless command link to stop the machine recording, the timing of the stop signal being in accordance with the programme information detected.

Description: "Apparatus and method for controlling a recording machine" The present invention relates to an apparatus and method for controlling a recording machine, which incorporates a tuner, by way of a wireless command link, for example an infra-red link. The invention is especially, but not exclusively, concerned with the control of a video recorder for recording broadcast television signals. There have been various proposals for incorporating control signals in a broadcast signal so as to switch a video recorder on and off at the beginning and end of a programme to be recorded. Such a system has the advantages that the user of a video recorder does not have to go to the trouble of setting the recorder to record the programme, that the risk of a programme not being recorded as a result of user error is substantially reduced or eliminated and that the timing of the broadcast to be recorded may be shifted and, provided the control signals are correspondingly shifted, the whole programme can still be recorded. Such arrangements clearly offer very significant advantages but have not to date proved a significant commercial success. A difficulty that arises is that many persons who might wish to make use of such a system already have a video recorder and therefore would like such arrangements to make use of their existing recorder. That however has not hitherto proved possible because of the limited intel¬ ligence of video recorders and the variation in the control signals to which they react. A further difficulty for achieving commercial success with such a system is the practical difficulty of requiring a substantial amount of installation work in order to set up such an arrangement in a home. It has been proposed in GB 2 192 743 to pass the broadcast signal from an antenna via a controller to a video recorder. The controller receives and demodulates the broadcast signal and decodes control signals in the demodulated signals. The control signals are then encoded into a form which mimics the control signals from the video recorder's conventional hand-held unit. An advantage of the arrangement is that the controller can be installed without adapting the internal structure of the video recorder, but the arrangement suffers from the disadvantages that the controller must be tuned in to the broadcast signal by the user as part of the installation of the controller and that, because of the need for the demodulating stage, the controller is relatively expensive. The present invention seeks to overcome or at least mitigate the problems referred to above. In accordance with the invention, a method of controlling a recording machine, incorporating a tuner, in order to effect the recording of a programme included among transmissions of a number of programmes, comprises the following steps: transmitting information about programmes in a transmission, receiving the transmission and passing it to the recording machine, passing the transmission through the tuner of the recording machine and passing a baseband output signal including the programme information from the recording machine to an apparatus for controlling the recording machine, detecting the programme information in the baseband output signal from the recording machine by means of the apparatus for controlling the recording machine, sending a start signal from the control apparatus to the recording machine via a wireless command link to start the machine recording, the timing of the start signal being in accordance with the programme information detected , and sending a stop signal from the control apparatus to the recording machine via the wireless command link to stop the machine recording, the timing of the stop signal being in accordance with the programme information detected. The indications of the start and stop times may provide the actual start and stop times or may provide the actual start times and the durations of the programmes. Alternatively, the start and stop times may be the elapsed times from a reference time. According to the invention, the control apparatus is connected to receive a baseband output signal from the recording machine. As a result there is no need for the control apparatus to include any tuning/demodulating stage so that the control apparatus can be made more cheaply and does not itself require tuning to the broadcast signal upon installation. By providing what would be a strange combination of both a link (that would normally be a wired link) from the baseband output of the video recorder to the control apparatus and a wireless link from the control apparatus to the video recorder, an especially advantageous arrangement is obtained. The control apparatus can be connected up to most video recorders without any alteration since they will already have a baseband video output port to which a cable can be connected and they will also have an input port forming the receiving end of a wireless command link. Thus an owner of a video recorder can easily and cheaply adapt the recorder to enable it to be controlled by signals included in the broadcast transmission. In the intended use of the control apparatus, back- scattered infra-red light from its command transmitter reaches the receiver of the video recorder. Advantageously, the method of controlling the recording by a recording machine includes provision for a user to set the control apparatus to provide a group of command sequences according to the recording machine type. Preferably, the method of controlling the recording by a recording machine includes provision of a plurality of groups of command sequences for respective recording machine types, and provision for a user to select, for use, a group of command sequences, according to the recording machine type. The programme information is preferably transmitted at preselected times. The control apparatus can be activated, or brought to a higher level of activity, at those times in order to receive the programme informa¬ tion. The preselected times may be, but need not be, regular. The programme information may include an indication of the time at which the next transmission of programme information will occur. It is common in a television transmission for programme information to be transmitted during the vertical blanking interval. However, according to an especially advantageous feature of the present invention programme information is transmitted during the active part of a television transmission. Preferably the programme information is transmitted as digitally coded data which modulates the luminance component of the video transmission. Preferably, the programme information is inserted into the active lines which are not visible on a correctly adjusted display such as, for example, the top and bottom lines; in a 625 line system those would be lines 24, 25, 309 and 310. It has already been indicated that there is prefer- ably provision for a user to set the control apparatus to provide a group of command sequences according to the recording machine type. Instead or in addition to this it may be advantageous to provide a facility which allows the form of the command sequences to be altered by the broadcaster; in that case there is no limit to the number of different forms of command sequences that can be provided. Thus the programme information preferably includes information relating to the form of the signals transmitted from the control apparatus to the recording machine via the wireless command link. The programme information may include an indication of the channel to which the recording machine is to be tuned for recording and the control apparatus may send a channel selector signal to the recording machine via the wireless command link to select the channel on which the recording machine is set to record. This enables programmes on a plurality of channels to be recorded. The programme information may be transmitted on different channels at different times and the control apparatus may be able to monitor trans¬ missions on the different channels for the programme information by tuning the recording machine to each of the channels in turn. The control apparatus may be responsive to some only of the programme information. In that way it is possible for the control apparatus to select certain programmes only for recording. One of the factors that may determine which programme information the control apparatus is responsive to may be the category of user of the control apparatus. The selection may involve discarding some information after storing all the transmitted programme information. The control apparatus may be alterable by a user to vary which programme information it is responsive to, for example by inserting a "key" into the apparatus. In that case the user is able to select which programmes are recorded. Some of the programme transmissions may be encrypted, in which case the control apparatus decrypts the transmissions. Such arrangements are especially advantageous in subscription broadcasting systems and/or where the information broadcast is not suitable for viewing by the whole of the audience to which it is broadcast. The encrypted programme transmissions are preferably recorded in encrypted form and the control apparatus decrypts the transmissions during playback. In that case a person who obtains the recording is not able to view the recording without the aid of the control apparatus. The encrypted programme transmissions may be line- by-line transmissions in which selected lines of the transmission are inverted to encrypt the transmissions and the amplitude of each line of the decrypted transmission is controlled in accordance with the amplitude of a digital sound signal recovered from the recording machine. A special word may be transmitted with a encrypted programme and used to decrypt the transmission. The special word may be expanded to generate a sequence of binary states for decryption of the stored programme. According to the present invention there is also provided an apparatus for facilitating the recording of a programme transmitted among other programmes in a programme transmission system in which information about programmes is included in programme transmissions, comprising: a recording machine which incorporates a tuner and is capable of receiving a transmission by way of an antenna port and of providing a baseband output signal resulting from the passing of the transmission through the tuner, the recording machine including a receiver port of a wireless command link through which it is controllable, control apparatus connected to receive the output signal from the recording machine and capable of detect¬ ing programme information in the output signal from the recording machine, the control apparatus including a transmitter part of the wireless command link for controlling the recording machine, the control apparatus being capable of sending a start signal followed, in due course, by a stop signal, by way of the wireless command link, for facilitating the recording of a programme by the recording machine, wherein the times at which the start and stop signals are sent are in accordance with detected programme information. Advantageously, the apparatus includes a data storage system for storing programme information. Advantageously, the apparatus includes a data storage system arranged to store programme information which includes indications of the time at which control instructions to start and stop recording by the recording machine are to be transmitted to the recording machine by way of the wireless command link. Advantageously, the control apparatus, in use, is set to detect programme information contained in the transmission at particular times only. Advantageously, an indication of the time at which the next transmission of programme information will occur is included in programme information held by the data storage system, during operation of the apparatus. Advantageously, an indication of the channel on which the transmission to be recorded will be broadcast is included in programme information held by the data storage system, and the control instructions transmitted by the wireless command transmitter include an instruc¬ tion for tuning the recording machine to a particular channel, during operation of the apparatus. Advantageously, the control apparatus is arranged to detect programme information contained in a transmission on any one of a plurality of channels, and is capable of tuning the recording machine, by way of its command receiver, to each of the available channels in turns, for receiving programme information. Advantageously, the control apparatus is capable of being selective as to which programme information it is responsive to for transmitting control instructions to the recording machine. Advantageously, the control apparatus is capable of storing, initially, all the received programme information and, subsequently, of discarding programme information to which it should not respond. Advantageously, the apparatus includes a key-holding data storage system that acts as a key in selecting which programme information the apparatus is responsive to, the key being stored in the apparatus with a part of the programme information. The key-holding data storage system may not be accessible to or alterable by, a user. A user may be provided with a key which he inserts into the apparatus in order to select the programme information that the apparatus is responsive to. A variety of keys may be available according to what programme information the apparatus is required to be responsive to. Advantageously, the control apparatus is suitable for use in an encrypted programme transmission system, and includes a decryption system capable of capturing a special word transmitted as part of the programme information and of expanding captured special word to generate a sequence of binary states for decrypting a programme stored in encrypted form by a recording machine connected to the apparatus and controlled by it. Advantageously, the apparatus is suitable for use in an encrypted programme transmission system using line-by¬ line transmission in which selected lines of the transmission are inverted to encrypt transmission, and in which a digital sound signal is transmitted, the apparatus including a system for controlling the amplitude of each line of the decrypted transmission in accordance with the amplitude of the digital sound signal recovered from the recording machine. Advantageously, the apparatus comprises a video recording machine having the control apparatus connected to its baseband video output port, for facilitating the recording of television programmes. Advantageously, the apparatus comprises a video recording machine having the control apparatus connected to its baseband output port by way of a wired connection, for facilitating the recording of television programmes. The control apparatus is advantageously a unit capable of operating with a recording machine, which incorporates a tuner, and includes an input port which, in use, is connected to an output port of a recording machine which, in operation, provides a baseband output signal by way of its tuner at the output port, a transmitter which is a part of a command link for controlling the recording machine which carries a receiver part of the wireless command link, and a detection system capable of detecting programme information in the baseband output signal received from the recording machine and of signalling the recording machine by way of the command link according to the detected information. The control apparatus is preferably a separate unit and can be defined without requiring the presence of the recording machine. Thus according to another aspect of the invention there is provided a control apparatus including an input port for connection to an output port of a video recording machine which, in operation, provides a baseband output signal, means for extracting control information from the baseband output signal and a transmitter or generating and transmitting a control signal containing said control information from the apparatus over a wireless command link. As has already been indicated, the transmission of the programme information during the active part of a television transmission is a special feature of embodimentof the present invention and may indeed be used even in cases where the control apparatus itself includes a tuner. Thus the present invention provides a method of controlling a recording machine, incorporating a tuner, in order to effect the recording of a programme included among television transmissions of a number of programmes, the method comprising the following steps: transmitting information about programmes in a television transmission, the programme information being transmitted during the active part of the transmission, receiving the transmission and passing it to the recording machine, passing the transmission directly or indirectly to an apparatus for controlling the recording machine, detecting the programme information in a baseband output signal by means of the apparatus for controlling the recording machine, sending a start signal from the control apparatus to the recording machine via a wireless command link to start the machine recording, the timing of the start signal being in accordance with the programme information detected, and sending a stop signal from the control apparatus to the recording machine via the wireless command link to stop the machine recording, the timing of the stop signal being in accordance with the programme information detected. Two examples of an apparatus in accordance with the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a block diagram representation of a first form of the apparatus which is capable of recognising baseband signals representing a list of programmes to be transmitted and the transmission times, and capable of switching on and switching off a recording machine at a time, or at times, to record selected programme material the control of the recording machine being effected by way of its wireless-command link; and Fig. 2 is a block diagram representation of a second form of the apparatus which is capable of carrying out the functions of the first form of the apparatus, as represented by Fig. 1, and, also, is capable of causing a recording machine to record an encrypted signal and of decrypting the encrypted signal. Referring to Fig. 1 of the accompanying drawings, a first form of an apparatus for controlling a recording machine includes an input port 1 belonging to an input circuit 2, a main controller 3 , a digital code switch 4, an infra-red transmitter 5, a read-write memory 6, a read-only memory (ROM) 7, a time-keeping device 8, and a display device 9. There are bi-directional connections between the main controller 3 and the input circuit 2 , the digital code switch 4, the infra-red transmitter 5, the read- write memory 6, the ROM 7, and the time-keeping device 8, by means of which connections the main controller 3, is able to control, synchronise its operations with, or to interrogate each of those components of the apparatus. There is a unidirectional connection between the main controller 3, and the display device 9. The apparatus represented by Fig. 1 is suitable for controlling a video recording machine, in which applica- tion the baseband video output port of the video record¬ ing machine is connected by wire to the input port l of the apparatus. The apparatus is suitable for use in and will be described in relation to a programme transmission system in which information about programmes is transmitted at a specific time, in advance of the programme transmissions, and information about each programme is transmitted with the programme. It should be understood, however, that the apparatus may be used in other programme transmission systems. The apparatus operates as follows: The main controller 3 is able to exercise full control of a video recording machine (not shown) equipped with an infra-red command receiver, by way of the infra¬ red command receiver, by the use of the infra-red transmitter 5 which is equipped to generate commands recognisable by the command receiver of the video recording machine. The time-keeping device 8 is capable of keeping a record elapsed time relative to a datum signal and may be capable of recording the time of day. The time information is made available to the main con- troller 3 which uses the time information to switch on the video recording machine at the time of transmission of information about programmes to be transmitted, and to record the information in its read-write memory 6 after it has been extracted by the input circuit 2 and con- verted to a form suitable for the read-write memory 6. The main controller 3 is also able to determine, from codes entered at the digital code switch 4, by the user of the apparatus and video recording machine, which programmes the user wishes to record, those programmes being categorised according to their contents. The information transmitted in advance of the programmes indicates the category of each programme and the scheduled time of its transmission, and the information transmitted with the programme also indicates the content of the programme, such as, for example, sport, news, and so on. Referring still to Fig. 1, and to the operation of the apparatus which it represents, the main controller 3 is able to compare the data provided by the digital code switch 4 with the information that has been stored in the read-write memory 6, and, from the information and the data, to determine those times at which the video recording machine should be switched on and commanded to record, in order to obtain recordings of the programmes with content as indicated by the user. The main con- troller 3 now stores in the read-write memory 6, those times at which the video recording machine is to be switched on and caused to record, and may discard that originally stored information which relates to trans¬ mitted programmes which are not to be recorded. The main controller 3 switches on the video recording machine at the time of the first programme to be recorded and monitors the information it receives by way of its input port 1 and the input circuit 2, looking for the information, transmitted with the programme, indicating the programme content, and compares information relating to the content of the programme with its stored data as to the content of the required programme. Assuming that the main controller 3 finds information which is trans¬ mitted with the programme and that information indicates that the programme is to be recorded, the main controller 3 instructs the infra-red transmitter 5 to transmit the"record" command for the video recording machine. Referring still to Fig. 1, and to the operation of the apparatus which it represents, the transmitted programme includes, at the end of the transmission, information indicating that the transmission of that programme has been completed, and the main controller 3 is capable of recognising that information and respond¬ ing to it by stopping the video recording machine and switching it off. The main controller will repeat the procedure of switching on the video recording machine at a time specified by the information held in the read- write memory 6, checking that the content of the programme which is about to be transmitted is of a category to be recorded, record the programme if it has the required content, and stop and switch off the video recording machine, until it has carried out the procedure in respect of each programme noted as "to be recorded". The display device 9 is used to indicate to the user that a programme has, or programmes have, been recorded, and may be no more than a lamp or light emitting diode, although a more sophisticated display may be provided. It has been explained above that the apparatus represented by Fig. 1 is suitable for use in a programme transmission system in which information about future programme is transmitted at a specific time, and informa¬ tion about each programme is transmitted with the programme. The advance information about programmes takes the form of a list of the programmes to be transmitted. The list may be transmitted alone or as part of a programme. The programme information is transmitted as digitally coded data which modulates the luminance component of the video transmission in a manner that is compatible with the transmission network link. The programme information is inserted into lines of the active picture area; in a 625 line system, lines 24, 25 and 309,310 at the top and bottom of the active picture area may be used. The list is transmitted on more than one occasion and includes, at each transmission, information as to the date and time of the next transmission of the list and the channel on which that transmission will be effected. The following further information is, or may be, included in each list: a. A signature which includes an indication of the number of programmes to be transmitted. b. The current date and time. c. The time to the next transmission of the list of programmes. d. Access/address information (discussed below) . In addition, each list will include the following information about each programme on the list: e. A programme category description. f. The starting time of the programme. g. The time to the start of the programme. h. The channel on which the programme will be transmitted. j. The duration of the programme. k. The finishing time of the programme. It will be evident that some of the information included in each programme list may be redundant; for example the starting time of the programme (f) and the time to the programme (g) convey substantially the same information and, the duration of the programme (j) and the finishing time of the programme (k) , also, convey substantially the same information. The use of time to the programme (g) and the duration of the programme (j), would ensure that recording of the programme will be effected when the apparatus has a clock capable of registering the time of day and disagrees with the transmitter clock as to the time of day. If, of course, there are two clocks registering time of day and both clocks register the same time of day, or the apparatus is capable of correcting its own time-of-day clock to make it agree with the time of day given in a transmitted list, the apparatus may then use the starting time of the programme (f) and the finishing time of the programme (k) , for recording the programme. The access/address information, included in each list, is a means of restricting the reception of the list to authorised users (usually those who have paid a user's subscription). User access/address information is transmitted to the apparatus according to whether or not a user has paid a subscription. Users may be required to pay, in effect, a separate subscription for each programme category they wish to receive, and the transmitted information is used to load into each user's apparatus, a code, or codes, indicating the categories of programme to which that user is allowed access. Each user's apparatus may have a unique identification number. Users cannot, therefore, receive programmes for which they have not paid a subscription and have, as a result, not been supplied with access codes. The access/address information can be transmitted as a packet with a structure designed to accommodate a hierarchial broadcaster/programme category/sub-category/ user-category structure, with optional command extensions to allow a specific user or group of users to have their access rights to broadcast categories modified. The inclusion of a user-category enables a programme to be transmitted to a particular user group; a user group may be selected according to any combination of a wide variety of parameters which may be known or assumed for a given user; examples of such parameters are geographical location, wealth, hobbies and occupation. The advance information about programmes will, of course, be updated at each transmission of the list in order to take account of the rescheduling or cancella- tion of particular programmes, and the apparatus is capable of updating the programme information which it holds in its data store. The programmes themselves may sometimes be transmitted at times when the television system would otherwise be idle, at between 2 a.m. and 6 a.m., say, and the apparatus is intended to facilitate recording of those programmes for viewing at a more convenient time. The system includes no facilities for encryption of the signals and the apparatus includes no facilities for decryption of signals. Referring again to Fig. 1, the main controller 3 is capable of effecting the storage of the list information when it is transmitted and of reacting to the information contained therein relating to a future transmission of the list information. In the operation of capturing the list information, the main controller switches on the recording machine, by way of its infra-red controller, and monitors its baseband video signal output port by virtue of the connection of the input port 1 to the baseband video signal output port. The main controller 3 may be capable of switching the recording machine cyclically through the channels on which it will receive programmes for information transmitted in advance of, or with, a programme, thereby permitting greater freedom in the selection of a channel, by the transmitting authority, for transmitting a programme list. In a system in which the main controller 3 is capable of switching the recording machine cyclically through the channels for the purpose of detecting advance information, the advance information may, for example, be preceded by a recognition code which is repeated. The use of the repeated code would ensure that the main controller 3 has time to check all the available channels while the recognition code is being transmitted. Referring to Fig. 2 of the accompanying drawings, a second form of an apparatus for controlling a recording machine, providing facilities for decrypting programme material which has been encrypted in a particular manner, includes an input port 100, a phase splitter 107, a video switch 106, an interface circuit 101, a controller 102, an infra-red transmitter 103, a sound data separator 104, a digital-to-analogue (DAC) converter 105, a digital code switch 109, and a display device 110. The apparatus represented by Fig. 2, is suitable for the control of a video recording machine and will be described further as though connected to a video recording machine. Referring to Fig. 2. the input port 100 is connected to the phase splitter 107 and also to the interface circuit and the sound data separator 104, that is, the input port 100 is shared by the phase splitter 107, the interface circuit 101, and the sound data separator 104. The interface circuit 101 has three output ports which are connected to input ports of the controller 102. The sound data separator 104 has a single output port which is connected to an input port of the controller 102. The phase splitter has two output ports which are both connected to input ports of the video switch 106, and a further input port of the video switch 106 is connected to an output port of the controller 102. An output port of the controller 102 is connected to an input port of the digital-to-analogue converter 105, and a further output port of the controller 102 is connected to the infra-red transmitter 103. The video switch 106 has an output port 108 and the DAC 105 has an output port 109. The output port 108 would, in the use of the apparatus, be connected to a video monitor and the output port 109 would, in the use of the apparatus, be connected to a sound reproduction system. The infra-red transmitter 103 is capable of providing an infra-red beam 111. The digital code switch 109 has a bi-directional connection to controller 102 and the display device 110 has a unidirectional connection to the controller 102. Referring to Fig. 2, the interface circuit 101 is capable of performing all of the functions of the input circuit 2 of Fig. 1, in addition to other functions, and the infra-red transmitter 103 is substantially the same as the infra-red transmitter 5 described with reference to Fig. 1. The controller 102 is capable of performing substantially all of the functions carried out by the main controller 3 of Fig. 1 except that it is not capable of responding to signals transmitted at the time of the transmission of a programme for starting or stopping a recording machine. This difference between the con¬ troller 102 of Fig. 2 and the main controller 3 of Fig. 1 is described in more detail below. However, like the main controller 3 of Fig. 1, the controller 102 of Fig. 2 incorporates a time-keeping device, a ROM, and a read-write memory. The apparatus represented by Fig. 2 is also suitable for use in a programme transmission system in which information about future programmes is transmitted at specific time, but the operation of the apparatus as regards the switching-on for recording, and the switching-off of the recording machine is significantly different from that of Fig. 1, and there are differences, relating to the matter of recording, between the programme lists usable with the apparatus of Fig. 2 as against the apparatus of Fig. 1. The advance information for the apparatus of Fig. 2. also takes the form of a list of programmes. The list may, as before, be transmitted alone or as part of a programme. The programme information may be transmitted in the same manner as described above with reference to Fig. 1. Additionally, however, the list may be trans¬ mitted in encrypted form, in an encrypted programme. Each transmitted list, for a system with encryption, includes the following information: a. The time to the next transmission of a list. b. The channel on which (a) will be effected. Each transmitted list, for a system with encryption, includes, for each programme in the list: c. The time to the programme. d. The channel on which transmission will take place. e. The category of the programme. f. The duration of the programme, or alternatively, the time at which the programme ends. The apparatus represented switches on the recording machine at the scheduled time of transmission of the list by the use of the information time to the next transmission of a list (a) (obtained from the previous list), and extracts and stores the list information in its read-write memory. The controller 102 carries out the function of examining the stored list and of discarding any programmes that the apparatus is not authorised to receive. The lack of authorisation may arise because the user has not paid a subscription for that material and his apparatus has, therefore, not been provided with the with the relevant access/address code, or because that he does not wish to record that material (although authorised to do so). The transmission system effects the repeated transmission of the programme list in order to provide the controller 102 with a clear opportunity to select, and to store, a complete and correct programme list. Subsequently, the apparatus, through the controller 102 switches off the recording machine but monitors the time to the first programme. When the first programme is due to be transmitted, as indicated by the stored programme list, the apparatus activates the recording machine by way of the infra-red command link, switching it on, selecting the appropriate channel and issuing the command to record. Once it has issued the command to record, the apparatus keeps track of time through a "duration of programme" value and, when that "duration of programme" value reaches that indicated in the stored list, the apparatus issues a command to stop the machine recording and switches off the machine. The operation effecting recording is effected for each event on the programme list until the recording of all items on the list has been effected, at which time the apparatus may command the rewinding of the tape before finally switching off the recording machine. The rewinding of the tape may be effected by issuing the command effecting the switching-off of the recording machine. The transmission system is able to accommodate changes of the programme schedule, following the transmission of the programme list, by the transmission of a sub-list, or sub-lists, detailing programme delays or the rescheduling of programmes, and the apparatus is capable of making the relevant adjustments to its stored list. The input port 100 is connected to the baseband video output port of the video recording machine and, as has been described, the apparatus is able to obtain programme lists by switching on the recording machine and examining the information presented at its input port 100. Also, the apparatus is capable of operation in accordance with the information provided by the user, through the setting of the digital code switch 109, as regards desired programme material. Referring still to Fig. 2, and to the operation of the apparatus, recorded programme material will, in this case, be encrypted, and, in the playback mode of the video recording machine, the programme material presented at the input port 100 will be encrypted material. Encrypted material that the apparatus of Fig. 2 can decrypt has the form of a line by line television transmission in which some of the lines are inverted, without encryption of the synchronising pulses. The apparatus is capable, in addition, of decrypting digitised sound which would accompany the encrypted picture material. Referring still to Fig. 2 and to the operation of the apparatus, an encrypted baseband video signal with digitised audio is received by the input port 100. The interface circuit 101 extracts the line and field synchronising pulses from the input signal and passes them separately to the controller 102. The interface circuit 101 also extracts a special word from the input signal, and the controller 102 uses the special word to generate a sequence of binary states for decrypting the signal. The sequence of binary states indicates which lines have been inverted and, therefore, require reinversion. The transmitter uses the same special word to generate the same sequence of binary states that the controller 102 generates, and, thereby, consistent encryption and decryption are achieved. The input signal is received, also, by the phase splitter 107 which generates normal (upright) video signals, and inverted video signals, and passes those signals to the video switch 106. The video switch 106 is controlled by the controller 102 which selects, in accordance with the decryption information, a mixture of normal video signals and inverted video signals, and by that selection, provides a decrypted video output signal for application to a television monitor. The sound data separator 104 receives the input signal, selects the digitised sound information, and passes the digitised sound information to the controller 102. The sound information reaching the controller 102 will be in the form of bursts occurring at the beginnings of lines of video, or at the ends of the lines of video, or at both the beginnings and the ends of the lines of video, and the controller performs the task of retransmitting the sound information at a constant rate throughout the video fields. The constant rate sound information is sent to the digital-to-analogue converter 105 which provides an output sound signal suitable for driving a conventional sound reproduction system. The code switch 109, which facilitates the entry of particular codes by the user, may include facilities for the user to enter a code which is necessary for the decryption of the encrypted programme. The code that must be entered in order to facilitate decryption may need to be changed from time to time. Alternatively, the decryption-code-entry arrangement may be by means of a replaceable read-only-memory which the user may need to purchase. The gain of the video switch 106 is controllable by the controller 102 which uses the level of the digital sound signal it receives from the sound data separator 104 to assess the gain setting required for each line of the video switch 106. The sound data is a reliable indicator of the required gain because it includes no amplitude modulation. The active part of each video line is blanked at the time of transmission of the sound data. The command codes which the apparatus of Fig. 1, or Fig. 2, is capable of transmitting, preferably, originate from command data stored in ROM in the apparatus. The ROM 7 of Fig. 1, or the ROM belonging to the controller 102 of Fig. 2, is representative of all the ROM present in the apparatus and is intended to include, also, any ROM in which command data are stored. The command data stored in ROM may include, for command codes, parameters such as pulse width, frequency, number of bits per word, modulating frequency, if any, applied to each pulse, the presence of, length of, and shape of start, lead or trailer pulses and the number of correct receptions of any command required to cause the recording machine to execute a selected operation. Other parameters may be added, if required, and unimportant parameters may be omitted, as appropriate.

Claims: Claims : 1. A method of controlling a recording machine, incorporating a tuner, in order to effect the recording of a programme included among transmissions of a number of programmes, the method comprising the following steps: transmitting information about programmes in a transmission, receiving the transmission and passing it to the recording machine, passing the transmission through the tuner of the recording machine and passing a baseband output signal including the programme information from the recording machine to an apparatus for controlling the recording machine, detecting the programme information in the baseband output signal from the recording machine by means of the apparatus for controlling the recording machine, sending a start signal from the control apparatus to the recording machine via a wireless command link to start the machine recording, the timing of the start signal being in accordance with the programme information detected, and sending a stop signal from the control apparatus to the recording machine via the wireless command link to stop the machine recording, the timing of the stop signal being in accordance with the programme information detected. 2. A method according to claim 1 in which the programme information includes indications of the time at which control instructions to start and stop recording are to be transmitted to the recording machine. 3. A method according to claim 2 in which the programme information includes the times at which the programmes start and finish. 4. A method according to claim 2 in which the programme information includes the times at which the programmes start and their durations. 5. A method according to any preceding claim in which the programme information includes an indication of the channel to which the recording machine is to be tuned for recording and the control apparatus sends a channel selector signal to the recording machine via the wireless command link to select the channel on which the recording machine is set to record. 6. A method according to claim 5 in which the programme information is transmitted on different channels at different times and the control apparatus is able to monitor transmissions on the different channels for the programme information by tuning the recording machine to each of the channels in turn. 7. A method according to any preceding claim in which the control apparatus is responsive to some only of the programme information. 8. A method according to claim 7 in which one of the factors that determines which programme information the control apparatus is responsive to is the category of user of the control apparatus. 9. A method according to any preceding claim in which all the received programme information is stored initially and, subsequently, programme information to which the control apparatus should not respond is discarded. 10. A method according to any preceding claim in which the control apparatus is alterable to vary which programme information it is responsive to. 11. A method according to any preceding claim in which at least some of the programme transmissions are encrypted and the control apparatus decrypts the transmissions. 12. A method according to claim 10 in which the encrypted programme transmissions are recorded in encrypted form and the control apparatus decrypts the transmissions during playback. 13. A method according to any preceding claim i which the programme information is transmitted during th active part of a television transmission. 14. A method according to claim 13 in which the programme information is transmitted as digitally coded data which modulates the luminance component of the vide transmission. 15. A method according to claim 13 or 14 in which the programme information is inserted into the active lines which are not visible on a correctly adjusted display. 16. A method according to any preceding claim i which the programme information includes information relating to the form of the signals transmitted from the control apparatus to the recording machine via the wireless command link. 17. An apparatus for facilitating the recording of a programme transmitted among other programmes in a programme transmission system in which information about programmes is included in programme transmissions, the apparatus comprising: a recording machine which incorporates a tuner and is capable of receiving a transmission by way of an antenna port and of providing a baseband output signal resulting from the passing of the transmission through the tuner, the recording machine including a receiver part of a wireless command link through which it is controllable, control apparatus connected to receive the output signal from the recording machine and capable of detecting programme information in the output signal fro the recording machine, the control apparatus including a transmitter part of the wireless command link for controlling the recording machine, the control apparatus being capable of sending a start signal followed, in due course, by a stop signal, by way of the wireless command link, for facilitating the recording of a programme by the recording machine, wherein the times at which the start and stop signals are sent are in accordance with detected programme information. 18. An apparatus according to claim 17 in which an indication of the channel on which the transmission to be recorded will be broadcast is included in programme information held by the data storage system, and the control instructions transmitted by the wireless command transmitter include an instruction for tuning the recording machine to a particular channel, during operation of the apparatus. 19. An apparatus according to claim 18 including control apparatus arranged to detect programme information contained in a transmission on any one of a plurality of channels, which is capable of tuning the recording machine, by way of its command receiver, to each of the available channels in turn, for receiving programme information. 20. An apparatus according to any of claims 17 to 19, capable of being selective as to which programme information it is responsive to for transmitting control instructions to the recording machine. 21. An apparatus according to claim 20, in which the programme information to which the apparatus is responsive is alterable by a user. 22. An apparatus according to claim 20 or 21, which includes a key-holding data storage system that acts as a key in selecting which programme information the apparatus is responsive to, the key being stored in the apparatus with a part of the programme information. 23. A control apparatus capable of operating with a recording machine, which incorporates a tuner, to provide an apparatus according to any one of claims 17 to 22, including an input port which, in use, is con¬ nected to an output port of the recording machine which, in operation, provides a baseband output signal by way of its tuner at the output port, a transmitter which is a part of a command link for controlling the recording machine which carries the receiver part of the wireless command link, and a detection system capable of detecting programme information in the baseband output signal received from the recording machine and of signalling the recording machine by way of the command link according to the detected information. 24. A control apparatus including an input port for connection to an output port of a video recording machine which, in operation, provides a baseband output signal, means for extracting control information from the baseband output signal and a transmitter for generating and transmitting a control signal containing said control information from the apparatus over a wireless command link. 25. A control apparatus according to claim 24 in which the wireless command link is an infra-red link. 26. A method of controlling a recording machine, incorporating a tuner, in order to effect the recording of a programme included among television transmissions of a number of programmes, the method comprising the following steps: transmitting information about programmes in a television transmission, the programme information being transmitted during the active part of the transmission, receiving the transmission and passing it to the recording machine, passing the transmission directly or indirectly to an apparatus for controlling the recording machine, detecting the programme information in a baseband output signal by means of the apparatus for controlling the recording machine, sending a start signal from the control apparatus to the recording machine via a wireless command link to start the machine recording, the timing of the start signal being in accordance with the programme information detected, and sending a stop signal from the control apparatus to the recording machine via the wireless command link to stop the machine recording, the timing of the stop signal being in accordance with the programme information detected.

Inventors: ESDAILE ANTHONY ROBERT, STUART DAVID JAMES, THURLOW BARRY JOHN, ESDAILE, ANTHONY, ROBERT, STUART, DAVID, JAMES, THURLOW, BARRY, JOHN
Applicants: FERROGLEN RESEARCH LTD, FERROGLEN RESEARCH LIMITED
Application year: 1991
Main classification: G11B15
IPC codes: H04N5