MXPA98004180A - Method and apparatus for recovering the clock sign of the image signals m - Google Patents

Abstract

A home network architecture has an internal digital network that interconnects the device in the home: entertainment services are introduced into the network through network interface units that are coupled to an external network and the internal network; The network performs the necessary interface training between the external and internal networks and performs MPEG clock signal recovery from an MPEG video data stream, to avoid fluctuations when the MPEG data stream is transmitted through the internal network to the multimedia electronic components, the recovered MPEG clock signal is ensured by the network interface unit to the clock signal of the internal network and then it is transmitted through the internal network; the electronic components of multimedia then they retrieve the MPEG clock signal from the secured MPEG clock signal transmitted through the internal network, then the video data can eden be generated using the recovered MPEG clock signal and can be displayed, for example, on a television

Description

w- METHOD AND APPARATUS FOR RECOVERING THE CLOCK SIGN OF THE MPEG IMAGE SIGNALS RELATED REQUESTS This patent application is related to the US application serial number 0B / 5G1.758. filed on November 22, 1995. entitled Architecture of the Domestic Multimedia network; with the American application number of G * series 08 / 561.757. filed on November 22, 1995. entitled Inter-phase Unit Device. of multimedia. P'.ra electronic element and network; US application serial number 08 / 561,534. presented on November 22, 1995. entitled Transverse bar device / concentrator 5 for multi-media network FIELD OF THE INVENTION The present invention relates to digital or multimedia networks, and. in particular, to the recovery and securing of the clock signal of a video data stream. received in a digital home network, for conversion for use or display in household products, such as in televisions.

BACKGROUND OF THE INVENTION The rapid gains in digital technology and telecommunications have increased the convenience of having a network in the home to interconnect a multitude of products in the home, with each other "and with the outside world. A variety of outdoor services available include interactive services, video and audio cable services » # satellite networks. telephone company services »video by * application and other types of information services. However, the penetration of the personal computer in homes in the United States is approximately 33% and it is only growing slowly. although the Government wants more extensive penetration to promote "Tel econmutac n" and reduce traffic on roads and pollution. In addition, the penetration of computers in the home will originate from the purchase of entertainment products and information for the consumer. that contain a built-in computer and hidden operating systems by an opaque user interface.

This product is a conventional box with multimedia. Multimedia boxes are multimedia computers that increase the use of televisions. A conventional multimedia box has an external interface module with the network, which connects the multimedia box to the external network and data provider. The network interface module has to perform many complicated functions. such as forming an interface with a specific # - external network, tuning, demodulating, correcting errors, undoing the video mix, recovering the MPEG clock and encrypting and decrypting specifically with respect to the external network. Consequently. The network interface module is a relatively expensive component of multimedia boxes. This cost would be necessary even when only one television is present in the house. Nevertheless. Most homes contain several televisions, and each one provides its own multimedia box and its associated network interface module is 1G- a duplication of expensive components. One of the functions of the interface units with the network is the recovery of the MPEG clock signal, with MPEG-1 and MPEG-2 being different accepted standards for transmitting dig video data. MPEG data is a current continuous data normally controlled by clock at 27 MHz. In the conventional positions. where the unit # * interface with the network is coupled by a collector to the electronic elements of multimedia, there is little or no danger of degradation of the video signal due to nestability, since a local collector will not introduce substantial instability. In contrast, if the video data is placed on a shared network and distributed by means of a hub. Probability will be introduced through the home network. since the video data can be cushioned behind other data at certain points in the network. The greater the nestability, the harder it will be to recover * >; the clock in the electronic multimedia elements, when required. An exemplary home network that has a shared network is presented in an article entitled Resident to LAN Archi tecture, by Robert Olshansky and co-authors, IEEE publication number 0-7803-27560X / 95. In this article, the authors present several cases that refer to the feasibility of a shared network and suggest the use of a gate or? router and selected protocols to mediate between 0 * services / signals that compete in the shared network within the home. However, such solutions tend to be relatively expensive and may not adequately address the potential instability caused to MPEG signals. In order to provide a domestic multimedia network 5- relatively cheap. where MPEG data is available for multiple multimedia electronic elements »coupled to the net. it is necessary to accurately recover the MPEG clock in the separate multimedia electronic units.

BRIEF DESCRIPTION OF THE INVENTION The needs described above and others are met by the present invention which provides a method and an apparatus for accurately recovering the MPEG clock from an MPEG data stream. In certain modes »the MPEEG clock is recovered first in an interface unit with the network, coupled to an external network. A frequency synthesizer in the network interface unit secures the recovered MPEG clock to an internal network clock, such as an Ethernet clock. As an example, the MPEG clock can be 27MHz, and the Ethernet clock can be 10MHz. Thus, when the data packets are transmitted from the interface unit with the network to the electronic multimedia elements, the packages to the MPEG clock recovered, at 27 MHz. At the electronic multimedia element end of the internal network, another synthesizer regenerates the 27 MHz clock from the secured version of the watch. which is sent with the data packets, by the internal network. The present invention provides the advantage of allowing the transmission of MPEG video data over a relatively inexpensive home network such as the internet, without incurring instability. Another advantage of the present invention is that once the signal is secured to the recovered MPEG clock, it is easier and faster for any electronic multimedia unit to be secured to the signal. The above aspects and other aspects "features and advantages of the present invention" will become more apparent from the following detailed description of the present invention, when taken in conjunction with the accompanying drawings. f ^^^ BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic block diagram of a home network constructed in accordance with an exemplary embodiment of the invention. Figure 2 is an illustration of an exemplary installation of the home network of the present invention within a house. Figure 3 is a logic diagram of the home network of Figure 1 Figure A is a schematic illustration of an interface unit with the network and an electronic multimedia unit »constructed in accordance with the preferred embodiments from 1 to present invention. Figure 5 is a block diagram of an interface with the network of the electronic multimedia element, constructed in accordance with an exemplary embodiment of the present invention. Figure S is a block diagram of the terphase .O network of the interface unit with the network »constructed in accordance with an embodiment of the present invention. Figure 7 is a block diagram of a concentrator and a direct circuit cross bar, constructed in accordance with one embodiment of the present invention coupled to an interface unit with the network and an electronic multimedia unit.

Figure 8 is a logic diagram of an exemplary user interface for the home network of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED MODALITIES Figure 1 is a schematic illustration of a network and is home multimedia, constructed in accordance with one embodiment of the present invention. However, this * 10 mode, is only exemplary, since the network 10 can be configured in any of many different ways within the scope of the invention »and includes different devices coupled to the network 10. Additionally, the invention is not limited to networks located in houses, but is apl cable to networks in other types of structures »such as offices, apartment buildings» etc. However, for illustrative purposes, the exemplary mode will be described in the context of a home installation. Network 10 is a digital network that provides connectivity of different types of equipment to the outside world of the home. This equipment, for example, can consist of an analog TV 12. a digital television 14, a digital VCR 16 »a digital television camera 18, personal computers 20, audio equipment 22. printers 24» 2S fax machines and 2B telephones . among others. In addition to connecting this equipment to the outside world, the network also connects internally, in the home, the computer digital and digital audio and computer digital video equipment. This unifies the communication and control inside the house, making all the power of the external network connections or internal data sources available in any terminal of the network 10. The communication with the outside world is made through several interface with the separate network, (NIU) 32 and can be physically combined in an input unit 30, each interface unit 32 allowing a connection to the network # 10 between a different external network and the home network 10. Different external networks can carry different types of signals. These can be, for example, signals emitted (digital or analog / digital mixed) 1 leaded in hybrid fiber, in coaxial cable or in cable. Other types of signals are ISDN. broadcast / dig tal service by satellite. FTTC »FTTHC, ADSL, and others. At least the following types of data can be carried: compressed video, compressed audio, graphs and data, compressed internet WWW, internet email and other data »data for archiving in computer and message data control. Logically »all the terminals in the home network 10 receive equal access to the interface units 32 with the network and a user would not know how to identify them by their physical appearance. The number of 32 interface units with the network that are necessary is determined by the number of currents required for the home, for example, the number of different * > program channels (ie, video, audio, and others) that are required simul- ately, and not by the number of terminal units in a home. In certain preferred embodiments, the cable or antenna television is retained unchanged with the distribution by domestic coaxial cable regulating the old simple television or POTV). The POTS (old simple telephone service) is also carried on the home digital network 10. The digital signals are distributed throughout the house through an internal network 34. In certain preferred embodiments, the internal network 34 is essentially Ethernet of the home. Torque type of 10 bases R 100 bases T »but a special switch concentrator is used to make the network scalable to any number of terminal units, each of capable of receiving high bit rate video. The home network connects those computers or products with corporate computers that can support the network's working base width, protocols, routes, amortizations, and localizations. Others high bandwidth products that do not support this complex functionality must be linked to an anonymous unit »either directly or through a local peripheral network, to obtain interoperability. Examples of computers or products with embedded computers, located in the home network 10 that function as end-user devices, include: the IO input / output computers * of network interface units that perform the conversion of external network to home network and conditioning; and computers such as electronic multimedia elements (STE); personal computers, work stations. high-end printers, and special computers that provide gate / control functions. Other end-user devices that may be coupled to the network 10 include video products, compressed video (MPEG) and uncompressed video equipment; products of # 10- digital video camera; recording products on digital video tape and digital television display products and analogue television exhibition and recording products. The audio products that can be coupled to the network 10 include: Digital compressed audio equipment (MPEG) and no tablet »high-fidelity stereo; digital audio tape recording products. Other types of products that may be connected to the network 10 are data products, such as printers and other peripherals. Other more products that can be controlled through the IO network include automation and household appliances: central heating / air conditioning, safety controller, icroon oven and other kitchen equipment, lighting, sprinklers and other power controls . certain modalities of the home network 10 include one or more local peripheral networks 15 which provide local connection for future JPEG motion devices or I-only MPEG frame, high bit rate, audio devices, printers and similar peripherals. These devices require a continuous local digital connection at a high bandwidth, when the data transfer is continuous »for example, from a digital camera to a digital VCR. Accommodating said devices directly in the internal network 34 would require a greater bandwidth of the network throughout the network 34 than would normally be necessary. Instead, it # normally connects the peripheral network 15 by means of gate 10 to the internal network 34, for interoperability 1. However, in some other embodiments of the invention, the home network 10 is provided with peripherals and programs that accommodate the high-speed devices, so that the local peripheral network is not necessary. A domestic automation network 17 for home automation is provided. This home automation network 17 can operate on the power line or other low bit rate network, to control artifacts, "home security systems," lighting, etc.

This branch originates from a control computer 20, located inside the house. An exemplary model of the installation of the home network 10 of the present invention within a house 36. is illustrated in Figure 2. The home network 10 is a long-range structure, capable of running up to 100 meters of cable, for example , from a switched hub 38 that is part of the internal network 34. In the exemplary installation illustrated in Figure 2, the input unit 30 »with its units 32 in multiple network interface, are located in a service area of the network. home, together with the switched 38 concentrator. Twisted pair cable runs in each room of home 36 and ends in a wall receptacle. You can use, for example »Cat-5 twisted pair wire (for 100 Mbps), when an installation is performed, since most of the The cost is borne by the labor force. For temporary reinstallation. The twisted pair cable is small enough so that you can adjust it = the customer under the edge of a carpet. A user in the home will connect a computer product in a room »by plugging in the Ethernet port from the computer product to the Ethernet wall receptacle. In the embodiment of FIG. 2, the concentrator 38 is illustrated as a separate device, but in other embodiments, the concentrator 33 is integrated into one or more of the network interface units 32. The concentrator 38 provides connectivity to all areas of the home and to the unit or the various network interface units 32. When it is increased »to expand both the bandwidth and the connectivity of the internal network 34, an outlet is made additional or is changed to a larger concentrator. The concentrator will be discussed with more detail later. The present invention, as shown in FIGS. 1 and 2, separates the network interface functionalities 32 from the multimedia electronic elements 40. Conventionally, the multimedia box contains a network interface unit, whose components are internally connected by means of a collector to the multimedia electronic components. Nevertheless, in contrast, the present invention provides a separation of the network interface units 32 and the multimedia electronic elements 40, with the internal network 34 interposed therebetween. This arrangement allows the multiple electronic elements, multimedia, throughout the house 36, to be distributed less expensively, since the electronic elements of an interface unit with the network do not have to be duplicated for each of the elements electronic multimedia. Additionally, at having coupled separate interface units 32. to different external networks and to a common internal network 34. the owner of the house is freed from being forced to receive all the programming from a single source such as the telephone or cable company. The separation also allows the The owner of the house adds, removes or changes services simply by changing one of the interface units 32 with the network, without having to replace all the electronic elements 40 of multimedia, distributed throughout the house 36. In certain modalities »a box of "Master" multimedia is provided with multiple network interface units. Nevertheless. this mode is logically the same as * described above »since the network interface units are connected in this mode to the internal network, and not by means of a collector to the multimedia electronic elements. Figure 3 is a logical view of the home network 10 of the present invention. As is evident from the diagram, the switched, multi-port concentrator 38. forms the center of network connections. In certain modalities, where the instability between packages is adequately controlled » * a concentrator with a »traditional» switched package is available commercially. In other preferred embodiments, such as that illustrated in 1 to 3, the switched hub 38 is a combination of networked ports and ports that are switched directly (in circuits) for the duration of a session. The direct ports (connected and the systems) can be secured in phase by means of the network clock (coding). In order to provide this functionality "therefore" the switched concentrator 38 comprises a relatively simple and inexpensive concentrator 42"and a direct circuit crossbar 44. The concentrator 42" in certain modalities Preferred »may be a commercially available device» such as Am79C981 manufactured by Advanced Micro Devices »of Sunnyvale» California. The details of the direct circuit cross bar 44 will be described later with respect to Figure 7. A "star topology" as defined by Ethernet 10/100 T-bases is used in conjunction with the * switching hub 38. Switching hub 38 provides a range for most rooms in house 36. The maximum bandwidth of the system is a multiple of the bit rate of the wire ((bit rate per number of ports) / 2) per example 20 ports and 100 Mbits / s of bit rate equal to 1 Gb / s of maximum amplitude aggregate demand. The switched hub 38 allows the treatment # special for strongly asymmetric traffic. for example, 'compressed digital video and internet data, by sending these boxes directly from the transmitter to the receiver. This traffic * is thus separated from the internal network 34 and allows an aggregate global bandwidth to be limited only by the expansion capacity of the network. concentrator 38, although it remains limited by 10 Mbits / s by branch. The use of 100-base-T technology, instead of 10-base-T technology, will increase network speed, if necessary. The direct synchronous connections of the switching hub (Manchester or block coded) are primarily used for MPEG video transmission when a high-speed, long-duration, high-speed connection is required. The video of high bit rate, in compressed form can be up to 8 Mbits / s, and it is necessary for live video and for action films and sports. The low bit rate video is 1.5 Mbits / s. According to the present invention, the digital video MPEG is retained in the entire network 10. The conversion to real video takes place only in the external device (for example, in the television 12) or in the electronic element 40 of the television. Two separate direct circuits are illustrated as examples in figure 3. For example, the Network Interface Unit 32 which is coupled to an ISIN network is directly connected by means of the crossbar 44 of the direct circuit to the personal computer 20 of the local peripheral network 15. Another direct circuit separated by the bar is provided. transverse 44 of direct communication between a different network interface unit 32 (coupled to a hybrid fiber coaxial, (for example) and the electronic multimedia element 40, coupled to the television 12. Those devices that are not directly connected by means of of the cross-sectional bar 44 of direct circuit, remain connected to the connection mouth 42 and »in such a way» are worked in the network, with respect to the switching hub architecture »where a direct point-to-point path is configured» all the data that goes through this path is provided directly to the endpoint terminal of the trajectory »even the data destined to one or more of ot terminal terminals. Thus »in certain preferred embodiments. a rule is followed that the data passed by multiplexer »with the high data rate (typically message) must be sent to network terminals by the end point of the direct path returning said packets to the concentrator 38. For example» the messages sent through of the ISDN network »which are not intended for a device in the local peripheral network 15» will be returned by the local peripheral network host 20 to the concentrator 38 for distribution. These rules save the cost and complication of having a switch concentrator type of router * packets »with the demultiplexer operation distributed at the point O or endpoints» instead of centrally »and works well for the asymmetric data flow and the local destination» -ie, it is not subject to the switch layers. An advantage of the switched trajectories directly is that the potential delays in obtaining access to the network 34 (and, possibly, disturbing the delicate time control of the clock reference, carried in the MPEG stream) are avoided. The concentrator 38 »in certain modalities .0 preferred »must be" fully aware of a full duplex ", which means that a directly routed path connects only an" up "path of the transmitting terminal, only to a" down "path of the receiving terminal. In contrast »the downward trajectory The transmitter and the upward path to the receiver are not affected by the direct circuit and would normally be linked to the network, ie connected to all the remaining terminal paths, connected to each other. Specific routing occurs in response to user service requests. The messages are collected by the hub control and any direct routing changes are implemented. Non-switched devices are required from the connection to the network and not routers. The clock signal recovery is carried out • MPEG in the network interface units 32, such as »describes later. With the MPEG clock signal recovery in the network interface units 32, and the establishment of a direct circuit to the home network destination, the fluctuation in the signal received at the destination (such as on the television) is substantially eliminated. 12). The direct circuit capability works well for strongly asymmetric traffic from point to point in the domestic entertainment (video) scenario. For analogue only services, for example, cable television transmission, this is not considered part of the digital network. For digital / analog mixed services, such as hybrid fiber coaxial cable (HFC) and the newer forms of mixed cable television, this is considered a transition state and is treated as a temporary addition to the fully digital system of this invention. The signal of the hybrid fiber coaxial cable is directly provided to an electronic multimedia element 40 or to a combination of an interface unit with the network 32 / electronic multimedia element 40. 2 ports are needed to connect to the home network 10 »One for the interface unit 32 with the network and one for the electronic multimedia element 40. A derivation is provided in certain modalities referred to for linking the analog signals through the audio / video circuits of the electronic multimedia element 40. The home network 10 is controlled by means of a manual command or a computer keyboard for the application program running on the local terminals »such as the personal computers 20 or the electronic multimedia elements 40. The application program of control »local for each domestic terminal» manages source availability »bridge selection» path management by communication with the interface units 32 with the network »and the external gates. The external network protocols are regulated in the interface units 32 with the network "to provide a normal interface for the terminals in the home network 10. Figure 8 illustrates an example of a user interface. In this , the home network 10 is transparent and the user only indirectly realizes this by the number of connected services. Figure 4 is a block diagram illustrating a single network interface unit 32 coupled by the internal network 34 to a single electronic multimedia unit 40. The remaining portions of the home network 10, including the switching hub 38, are not shown in Figure 4. for purposes of illustration and explanation. The network interface unit 32 has one or more network interface modules 50. forming the interface of the network interface unit 32 with a particular external network. In the example of Figure 4, the network interface module 50 provides an interface for an external network carrying MPEG video data. The MPEG video data is provided to an internal network interface device 52 that prepares data for transport over the internal network 34. In certain preferred embodiments. the internal network 34 is an Ethernet network, so that the internal network interface device 52 is an Ethernet interface device. The architecture of the present invention assumes that for certain works it is necessary that a first end stage in the network interface unit 32 remains within a definable bandwidth limit (a current) instead of an amplitude. of arbitrary band »fixed by the construction of 1 to incoming current (multiple currents). If it is assumed that the MPEG2 video is being used. there is a demodulation of a multiple program transport stream to a single program transport, as defined in MPEG2 speci cation. This is accomplished by an MPEG transport capsule 54, such as the 9HOB capsule, commercially available from C-Cube. (A second step to demolish the video, the audio and other data, still occurs in the electronic multimedia element, while only the decoding in the display terminal or the computer is carried out). With this approach, it is not necessary to send high bandwidth currents through the entire house and the terminals in house 36 need only see an interface of a single standardized program. Compression is required for the video generated in the home, for example, a security camera in the front door or a video camera in the home.

The entire external network of interface, decryption, access control of demultiplexing for a current of a single program etc., is carried out by the network interface module 50. Thus, the module 50 of network interface regulates the artifacts and the application program of the domestic network, from the peculiarities of the external network j ^ j- connected. Multiple different programs require network interface cross-section connections, either from one or several providers. In certain modalities, it is provided a double module with two connections to the crossbar »which provides two programs received from the same external network. The MPEG transport pod 54 »operates the MPEG clock recovery and provides the recovered clock of 27 MHz and the selected program to an internal network connection 56. The 27 MHz clock is received by a MEPG to a network synthesizer 58 and converted to a 10 MHz clock, A for example, when the internal network 34 is an Ethernet network of 10 T base. The clock of 10 MHz, so as the selected program, they are provided to a conventional transmitter / receiver 60 (such as an Ethernet transmitter / receiver) connected to the internal network 34. The synthesizer 58 acts to secure the Ethernet clock to the recovered MPEG clock. When the data packet of the network interface unit 32 is transmitted to the electronic multimedia element 40, the electronic multimedia element 40 is secured to the MPEG 10 data "recovered at 27 MHz. In the electronic multimedia element 40, the 27 MHz clock is regenerated from the 10 MHz Ethernet clock, by another ".etherizer." The data is received in the electronic multimedia element 40"by means of a network interface device 62 which includes a network interface 64. The 10 MHz clock recovered by the network interface 64. of the data stream from the network 34. is passed through the gate 6G to a network for an MPEG synthesizer 68. The gateway is necessary for the insurance function to be carried out only when there is a data package present. The 10 MHz clock is converted to a 27 MHz clock provided for an MPEG decoder 70 and a video decoder / encoder 72. The selected program is provided by the network interface 64 to the MPEG decoder 70, which decodes the MPEG data and provides them to the video encoder / decoder 72. The data stream is converted by the video encoder 72 * • to a format (e.g., NTSC or SVideo) suitable for use by a device or display, such as a television. The video decoder is suitable for the case (HFC) where there may be an analog NTSC signal to dig it and connect it with an included graphics peripheral. Network 34 in Figure 4 is schematically illustrated and it should be understood from the previous description that video data can be placed in network 34 through hub 42, but that a direct circuit of the unit is preferred. 32 of the network interface and the electronic element 40 of multimedia, through the crossbar 44 of the direct circuit of the network 34, to provide a free transfer of fluctuation of the video data. Figure 5 is a more detailed diagram of a exemplary embodiment of the network interface device 62 of the multimedia electronic element 40 illustrated in Figure 4. The network interface device 62 includes the network synthesizer 6B coupled to a program logic device that operates as the gate device 66 The synthesizer 68 The network can be impli- cated by a commercially available capsule, such as MC145151 manufactured by Motorola. The program logic device 66 can be implemented by a commercially available capsule, such as MC7958, also manufactured by Motorola. An 80 crystal oscillator controlled in voltage »operates at 27MHz and provides its signal to the program logic device 62, which forms gate for the 10 MHz signal to the synthesizer 68. when a data packet is received. The synthesizer divides the frequencies of 10 MHz and 27 MHz at a common frequency "which is fed to a phase detector of the synthesizer 68. The phase detector output of the sicker 68 is provided as a control signal to the crystal oscillator 80 voltage controlled »to adjust the local frequency, up or down» to secure it to the incoming Ethernet frequency. The signal that informs the logical device 66 of < The program of receipt of a data packet, and the clock signal of 10MHz, are provided by a serial interface adapter 82 which serves as a reception host. A product commercially available, suitable for the serial interface adapter is AM7992B, manufactured by Advanced Micro 5 Devices. The data stream is received through a transformer / filter 84 »such as that which is commercially available from Pulse Engineering. the PE68026. The Collision information is also received through another Transformer / filter 86. which may be of the same type as the transformer / l ro 84. The received data is provided to a first transmitter / receiver 8B. such as a twisted pair Ethernet "plus" transmitter / receiver (Am79C100). The output of the first network transmitter / receiver 8B (the received data) is made available to the receptionist 82 and a controller 90. The controller 90 may be a commercially obtainable product S, such as Ethernet driver, single-capsule Am79C970 (manufactured by Advanced Micro Devices). The controller 90 is coupled to a collector 92"such as an interconnection collector with the peripheral component (PCI) to provide the data received from the network 34 to the MPEG decoder 70 of the electronic multimedia element 40. A second network transmitter / receiver 92 is coupled to the controller 90 and may be implemented by the same type of transmitter / receiver as 88. The second network transmitter / receiver 92 provides the transmission path for the data from the controller 90. »To network 34, through the transformer / filter 84. The collision information routed through the transformer / l ro 86 and the second transmitter / receiver 92 to the controller 90. Figure 6 is a more detailed diagram of the internal network connection 56 » which has an MPEG for the network synthesizer 58. which synthesizes the clock of 10 MHz to 0 from the MPEG clock of 27 MHz recovered by the MPEG transport capsule 54 (see Figure 4). A crystal oscillator 96 is coupled to the synthesizer 58 to provide a 10 MHz signal. In some embodiments, the crystal oscillator 96 is a 20 MHz oscillator. and the frequency generated by the synthesizer is 20 MHz, which is then divided simply by 10 MHz in the receiver (the electronic element 40 A of multimedia). A commercially available synthesizer is MC145145-2. manufactured by Motorola. The 10 MHz clock is provided to a microprocessor interface 98 which serves as an interface for a microprocessor 100. The microprocessor interface 98. with the microprocessor 100, they form the transmitter / receiver 60 which connects to the internal network 34 »through a transformer / filter 102. The microprocessor interface 98 * can be. for example. one MC68160 capsule »manufactured by 'Motorola, and the microprocessor can be an MC6SEN360. also manufactured by Motorola. The transformer / filter 102 may be of the same type as the transformers / filters 84, 36 of FIG. 5. The separation of the network interface unit 32 from the electronic multimedia elements 40 provides many advantages, such as those described above. The functions (responsibilities) of conventional multimedia boxes "with integrated network interface units, are divided into the embodiments of the present invention. For example. in the preferred modalities. unit 32 of network interface is responsible for the operation of specific interface training with the external network, the demodulation of the tuning and the correction of errors. It provides decomposition of the tangle of specific video from 1 to external network and encryption / decryption (credit card number, pass word of the user, etc.). The network interface unit 32 also provides a specific program guide of the network & external Additionally, it performs the demultiplexing of the MPEG transport to a single stream and the retrieval of the MPEG reference clock. In the preferred embodiments of the invention. the network interface unit. Provides Ethernet interface training in domestic 1 and assurance of MPEG / Ethernet clock. It also provides the application program to support the external network and home network protocols for multiple streams and multiple users. The network interface unit also has an application program O "to act as the gateway for the home network and control the retention of the data, when necessary." The multimedia electronic elements 40 act essentially as an application computer with an interphase interface. audio »video» graphics and analogue »in preferred modes.For example, the electronic multimedia element provides network-specific interface training and data retention, when necessary.It provides the assurance of Ethernet clock / watch MPEG in the Preferred modalities The electronic multimedia element 40 0 decodes the MPEG video and audio to recover digital audio / video, performs the conversion from digital to analog for audio and video and supports the commands of an infrared remote control. Multimedia 40 provides the support for analog video input 5 (NTSC). ports for games, etc. »and supports the operating system at the preliminary instruction level and is capable of downloading a complete system from an external network. The electronic multimedia element 40 supports application programs and communications through the network interface units, for a network provider and a program video server. Figure 7 is a block diagram illustrating in greater detail an exemplary embodiment of the arrangement of the hub 42 and the direct circuit connection bar 44 • of the present invention, and its connection to a unit of 10th network interface 32 and the electronic multimedia element 40. Crossbar 44 and 42 of direct circuit selectively provide a direct circuit between a particular network interface unit 32 and an electronic multimedia element 40, or a simple network connection through the concentrator 42 for those units. In FIG. 7, only portions of the network interface unit 32 and the multimedia electronic element 40 are illustrated for purposes of illustration and explanation. In the preferred embodiments of the present According to the invention, the concentrator 42 is a relatively simple and inexpensive concentrator, since it does not include any kind of packet router switch, storage and send switch. (Mo there is intelligence to examine the traffic and dynamically switch the concentrator according to the transmission and reception directions, as in the connection ports that have packet encapsulation switches. Although only a network interface unit 32 and an electronic multimedia element 40, directly connected in FIG. 7, are shown, any number of directly connected pairs can be connected via the direct circuit crossbar 44, depending on the size of the network. crossbar 44. The network interface unit 32 and the electronic multimedia element 40 are each shown with 5 leg positions or leg connections, each of the connections being a pair. This matches a conventional telephone socket, the RJ4 for telephone »which has ten leg positions. The internal network 34 provides the connection between the network interface units 32 »the electronic multimedia elements 40 and the direct circuit crossbar 44. In the preferred embodiments »the internal network 34 is Ethernet 10 base or 10 base. The selection of a network connection or a direct circuit between the network interface unit 32 and the electronic multimedia element 40» is established by means of several switches 108"as illustrated in FIG. 7" with literal suffixes to distinguish them from each other in the following description. In the example of Figure 7, the network interface unit 32 and the electronic multimedia element 40 are directly connected to each other, with the network interface unit 32 transmitting data to the electronic multimedia element *. A microprocessor 110 serves as a controller for the direct circuit crossbar 44 and controls the positions of the switches 108 in response to user commands that require a direct circuit to operate. For example, »a user can select to watch a movie from a video service per request» and therefore »make this selection in a manual remote control. The microprocessor lio »in response to this selection» will then change the positions of the switches 108 to set a direct circuit between the network interface unit 32. which is connected to the external network, which carries the video service per request, and the electronic multimedia element 40 which is coupled to the television receiver. in which the user wants to see the movie. In this case, the switch 108a is moved to its illustrated position to connect the transmission lines of the transmitter / transmitter 88 of network interface unit 32 to line 112 of transverse line 44 of direct circuit. The transmission lines of transmitter / receiver 8B no longer are connected to the network in the Txl port of the concentrator 42. If only »the receiving lines of the transmitter / receiver 92 of the electronic multimedia element 40 are connected through the switch 108 to the same line 112 of the crossbar 44 of direct circuit. With This direct circuit is now established. The data entering the house through the unit interface unit 32 are not transmitted via the network via the concentrator 42, but rather are directly provided to the electronic element 40 of the network. multimedia, in the location where the data will be used. Although the direct circuit established by the direct circuit crossbar 44 provides an excellent path for the data from the network interface unit 32 to the electronic multimedia element 40, it may happen that not all data entering the network unit 32 The network interface is significant for the electronic multimedia element 40. For example, it is possible that e-mail is received by this particular network interface unit 32 »and that the owner of the house wanted an e-mail to be directed to a personal computer but to a television. However, there is no connection to the network 34 due to the direct circuit »a ve2 that a direct 'circuit is established. To solve this problem. the electronic multimedia element 40 examines the addresses of the data packets it receives and performs an encapsulating function for the data that is not significant for this electronic multimedia element 40. The data is rerouted by the electronic multimedia element 40 in the network 34. through the concentrator 42. This re-connection by the connection of The end point (in this example the electronic element 40 of multimedia), avoids the need for the system to use a costly and complicated router. The electronic multimedia element 40 has a microprocessor 120 and associated memory 122 to identify and route the data packets back to the network 34. The direct circuit between the network interface unit 32 and the electronic multimedia element 40 provides a connection free of luctuations for the video data, but the re-routing of the other data to the network 34, through the concentrator, allows more than one type of data to be taken to the home "by the network interface unit 32 . Once the direct circuit between a network interface unit 32 and an electronic multimedia unit 40 is established, collision detection by the electronic multimedia element 40 is required to allow it transmitting it to the concentrator 42. The electronic multimedia connection element 40 needs to know about the collisions and 'retransmit the data to the network 34. if these collisions occur The network interface unit 32 can be set in some modes to disable the collisions, because it does not can occur in the direct circuit. However, in certain modes "both in the port of the network interface unit and in the port of the fixed port electronic element (to the network 34 through the crossbar 44), the same collision torque is included" for convenience. In some preferred embodiments, one of the five pairs of wire is available to provide image imaging capability for the system. For example »The network interface unit 32 can provide a second data stream through another transmitter / receiver 8Ba» by a second pair of transmission wires »to a separate crossbar connection line 114. The electronic element 40 of multimedia »having another transmitter / receiver 8Ba also connected to line 114» receives this second data stream through the direct circuit »to provide an image in image on a television screen. In such a way, said "images can be provided without fluctuations" by separate direct circuits In certain preferred embodiments of the present invention, the crossbar switches 108 are implemented by an analog MOS array of transistors, controlled in response to signals from controller 110. However. this is only exemplary, since other modalities employ switches of different design, as will be appreciated by one having ordinary experience in the art. Although the description of the invention illustrates the .0 provision of certain logical distinctions of 1 to functionality of various elements, those logical distinctions may be different in other modalities. For example. The concentrator 42 is described connected to the internal network. However, the concentrator 42 can also be logically considered as part of the internal network »or even form the network» with the remaining wiring forming means, to join the * terminal ends of the concentrator 42. Anyone who is an expert in the field »will therefore appreciate that the logical distinctions illustrated and described in the present specification are only exemplary. The separation of the network interface unit and the multimedia electronic element according to the present invention. it provides a relatively cheap connection of a multitude of devices, to each other »within the house, and with the outside world. Although the present invention has been described in detail, it is clearly understood that it has been by way of illustration and example only, and that it should not be considered in any way as limiting the spirit and scope of the present invention, that they are only limited by the terms of the re vindications that follow. ^ &

Claims (5)

# NOVELTY OF THE INVENTION CLAIMS

1. - A method for recovering and distributing an MPEG clock signal from an MPEG data stream in a network interface unit coupled to an external network, the network interface unit having an MPEG transport capsule for selecting a program of the current; characterized 1 i0"said method because it comprises: securing the recovered MPEG clock signal to an internal network clock signal, transmitting the selected program MPEG data, from the network interface unit, to an internal network, in accordance with the internal network clock, and retrieve the MPEG clock signal in the 15 electronic multimedia element coupled to the internal network, from the selected program MPEG data, controlled by the clock signal, on the internal network, according to the internal network clock signal, forming a gate for the data of MPEG of selected programs 20 received in the internal network, and retrieve the secured MPEG clock signal only when the selected program MPEG data is present in the electronic element of data.

2. The method according to claim 1, further characterized in that the internal network is an Ethernet network and the MPEG clock signal is 27 MHz and the internal network clock signal is 10 MHz. 3.- The method according to claim 1, further characterized in that the step of securing the recovered MPEG clock signal includes supplying to a frequency synthesizer the MPEG clock signal and the internal network clock signal; ensuring the frequency synthesizer the MPEG clock signal recovered to the internal network clock signal. "4.- The method in accordance with claim 1, 10 further characterized in that the formation of gates for the selected program MPEG data includes the use of a program logic device to form the compiler for the selected program MPEG data. 5.-A device to recover a clock signal 15 of MPEG from an MPEG data stream and transmit the MPEG clock signal recovered »by a network, characterized * 'said device because it comprises: a network interface unit that receives an MPEG data stream from an external network, the network interface unit having a circuit of 20 MPEG clock signal recovery to recover the MPEG clock from the MPEG data stream »including the MPEG clock signal recovery circuit an MPEG transport pod to select a program from the MPEG data stream , and a frequency synthesizer 25 to secure the recovered MPEG clock signal to an internal network clock signal; and the electronic multimedia element has a frequency synthesizer to recover the MPEG clock signal of the program controlled by the clock signal, in 1 to internal network, according to the internal network clock signal, and wherein the element multimedia electronic includes additionally a gate forming device that forms a gate for the program received in the internal network 1, and the electronic element of multimedia ensures the MPEG clock signal only when program data is present in the electronic multimedia element .