CN1311587A - Method and device used for data flow clock - Google Patents
Method and device used for data flow clock Download PDFInfo
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- CN1311587A CN1311587A CN 00108623 CN00108623A CN1311587A CN 1311587 A CN1311587 A CN 1311587A CN 00108623 CN00108623 CN 00108623 CN 00108623 A CN00108623 A CN 00108623A CN 1311587 A CN1311587 A CN 1311587A
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Abstract
A domestic network structure with digital network. Recreation service is led to the network by interface unit of network which connects internal and external network and restores MPEG clock from MPEG video data stream. When the MPEG video data stream is transmitted to top placed electrical device pass through the internal network, for avoiding vibration, the MPEG clock restored by network interface unit is locked into the internal network clock and is transmitted pass through the internal network, so the MPEG clock is restored by the one clocked and transmitted pass through the internal network by the top placed electrical device, then the video data is generated by restored MPEG clock and displayed.
Description
Present patent application is relevant with following application: the 1996.11.25 application, and title is " a home multimedia network framework ", US application serial No. No.08/561,758; 1995.11.22 application, title is " overhead electronic equipment and a network interface unit device ", US application serial No. No.08/561,757; 1995.11.22 the application, title for " be used for multi-media network in length and breadth/hub device ", US application serial No. No.08/561,534.
The present invention relates to the multimedia digital network, the clock recovery of the video data stream that particularly on digital home network, receives and locking, the conversion that is used for the household products such as TV is used or demonstration.
The fast development of digital technology and telecommunications has increased the demand to home network, a plurality of products in the family are interconnected and link to each other with the external world.The scope of available external service comprises the information service of interactive service, cable video and audio service, satellite network, telephone operator's service, order video and other types.Yet, in the U.S., personal computer to the popularity rate of family approximately be 33% and increase very slow, although government wishes wider popularizing to encourage " telecommuting " and to reduce road traffic and pollution.Computer will come from amusement and the information products that the consumer buys the operating system that comprises embedded computer and hidden by opaque user interface to further popularizing of family.Such product is a conventional top setting box (set-top box).
Top setting box is to increase the multimedia computer that TV uses.Conventional top setting box has an external network interface module that top setting box and external network are linked to each other with data set provider.This Network Interface Module must be carried out a plurality of sophisticated functionss, for example with the recovery of the interface of concrete external network, tuning, demodulation, error correction, video descrambling, MPEG clock and the relevant encryption and decryption with external network.Therefore, this Network Interface Module be top setting box relatively than expensive component.Even also must be expensive when having only a TV in the family.Yet most families comprise a plurality of TVs, just need many cover expensive components for each provides the top setting box of itself with relevant Network Interface Module.
A function of network interface unit is Motion Picture Experts Group (MPEG) clock recovery, and MPEG-1 is the different accepted standard that is used for transmission digital video data with MPEG-2.Mpeg data is general continuous data stream in the 27MHz clock synchronization.In the routine configuration, wherein network interface unit is connected to the overhead electronic equipment by a bus, almost or not has the degradation of the vision signal that causes owing to shake, and this is because local bus will not introduced tangible shake.On the contrary, if video data is placed on a shared network and distributes by a hub, introduce shake by home network probably, because the specified point of video data on network may be buffered in other data back.Shake greatly more, be not easy recovered clock on the overhead electronic equipment on request more.
For a kind of relatively inexpensive home multimedia network is provided, wherein mpeg data can be used for being connected to a plurality of overhead electronic equipments on the network, must accurately recover the MPEG clock on the overhead electronic device unit that separates.
The present invention satisfies above-mentioned and other needs, the invention provides a kind of method and apparatus that accurately recovers the MPEG clock from mpeg data stream.In certain embodiments, the MPEG clock at first is resumed in the network interface unit that is connected to external network.The frequency synthesizer that is positioned at network interface unit with the MPEG clock lock that recovers to internal network clock, for example ethernet clock.As an example, the MPEG clock can be 10MHz for the 27MHz ethernet clock.Like this, when packet when network interface unit is sent to the overhead electronic equipment, grouping is locked onto the MPEG clock of the recovery of 27MHz.At the overhead electronic equipment end of internal network, another synthesizer is from the locking pattern regeneration 27MHz clock of the clock that sends with packet through internal network.
The invention provides under the situation that does not occur shaking and to allow the MPEG video data, for example the advantage of Ethernet transmission through a relatively inexpensive home network.In case a further advantage of the invention is the MPEG clock that signal is locked into recovery, then any overhead electronic device unit is easier to and locks onto quickly this signal.
By below in conjunction with accompanying drawing to the detailed description that the present invention did, above-mentioned and other features of the present invention, aspect and advantage will become apparent.
Fig. 1 is the functional-block diagram according to the home network of example embodiment composition of the present invention;
Fig. 2 illustrates the demonstration of home network of the present invention in one family and installs;
Fig. 3 is the logic diagram of the home network of Fig. 1;
Fig. 4 is the network interface unit that constitutes according to a preferred embodiment of the invention and the schematic diagram of overhead electronic device unit;
Fig. 5 is the block diagram according to the network interface of the overhead electronic equipment of example embodiment formation according to the present invention;
Fig. 6 is the block diagram of the network interface of the network interface unit that constitutes according to one embodiment of present invention;
Fig. 7 is hub and the direct circuit block diagram in length and breadth that is connected to a network interface unit and overhead electronic device unit, constitutes according to one embodiment of present invention; With
Fig. 8 is the logic diagram of the example user interface of home network of the present invention.
Fig. 1 is the schematic diagram of the home multimedia network 10 that constitutes according to one embodiment of present invention.Yet this embodiment only is exemplary, because within the scope of the invention, network 10 can constitute with multitude of different ways, and comprises the distinct device that is connected to network 10.Therefore, the invention is not restricted to be positioned at the network of family, also applicable to other buildings, the network installed such as office, apartment building for example.Yet,, will install with regard to family and describe example embodiment for ease of explanation.
Network 10 is the internuncial digital networks that dissimilar equipment and family's outside world are provided.This equipment can be, for example, and simulated television 12, Digital Television 14, digital VCR16, digital camcorder apparatus 18, personal computer 20, audio frequency apparatus 22, printer 24, facsimile machine 26 and phone 28 etc.Except that this equipment is connected to the external world, network 10 is also with the portion's interconnection within the family of digital video, digital audio, computer and telephone plant.This has just unified communication and the control in the family, makes external network connect full power or internal data source and can be used for any terminal on the network 10.
With the external world communicate by letter by a plurality of network interface unit of separating (NIU ' s) 32 carry out, and can physical combination in gateway unit 30, each network interface unit 32 allows different external networks to be connected with home network 10.Different external networks can be loaded with dissimilar signals.For example, these signals can be the broadcast singals (numeral or analog/digital hybrid) that is loaded with on hybrid fiber/ coax, HFC or the cable.The signal of other types is ISDN, broadcasting/digital satellite services, FTTC, FTTH, ADSL and other signals.At least can be loaded with following data type: compressed video, compressed audio, compression internet WWW figure and data, internet E-mail and other data, computer file data and control messages data.
From in logic, all terminals in the home network 10 are access network interface unit 32 equally, and the user will be unaware of its physical state.The number of desired network interface unit 32 is by the required number of data streams of each family, and for example, the number of the different program channels that need simultaneously (that is, video, audio frequency and other) is determined, rather than determined by the terminal number in the family.
In some preferred embodiment, intactly keep wired or antenna TV (common old-fashioned TV, or POTV) by average family coaxial cable distributing signal.Also be loaded with POTS (ordinary old style telephone equipment) at family's digital network 10.
Digital signal spreads all within the family through an internal network 34.In some preferred embodiment, internal network 34 is the Ethernet of 10base-T or 100base-T multiple twin type substantially, but adopt a special switching hub so that network can be used for the terminal unit of any number, each terminal unit can receive the high bit rate video.
Comprise one or more local perimeter networks 15 among some embodiment of home network 10, this this locality perimeter network 15 provides following high bit rate, motion JPEG (motion-JPEG) or only this locality connection of I frame MPEG (I-frame-only-MPEG) video equipment, audio frequency apparatus, printer and other ancillary equipment.These equipment need continuous local digital to connect in high bandwidth, and wherein to transmit be continuous to the data from digital camera for example to digital VCR.Directly comprising these equipment at internal network 34 need have at whole network 34 and be higher than the usually required network bandwidth.Really, local perimeter network 15 generally is connected to the internal network 34 that is used for interoperability by gateway.Yet in some other embodiment of the present invention, home network 10 has the hardware and software of supporting high-speed equipment, and therefore local perimeter network 15 not necessarily.
For home automation provides family's automatic network 17.This family's automatic network 17 may operate in power line or other low bit rate networks, is used for control apparatus, home security system, illumination etc.This is started by a control computer 20 that is positioned at family.
Fig. 2 is illustrated in the demonstration of home network 10 of the present invention in the dwelling house 36 model is installed.Home network 10 is long-range main lines that reach the 100m cable, for example from the switching hub 38 of the part that forms internal network 34.Install in the demonstration shown in Fig. 2, the gateway unit 30 with its a plurality of network interface unit 32 is positioned at the tools area of dwelling house with switching hub 38.
Pair cable is connected to each room of dwelling house 36 and terminates in wall socket.For example, because most of installation cost is artificial, can use Cat-5 twisted-pair feeder (being used for 100Mbit/s) during installation.Install for temporary transient back, pair cable should be enough little so that its customization can be installed in edge of carpet.User in the family inserts the Ethernet wall socket by the ethernet port with computer product and comes at computer product of indoor connection.
At the embodiment of Fig. 2, hub 38 is expressed as an equipment that separates, but in other embodiments, hub 38 can be integrated into one or more network interface unit 32.Hub 38 is provided to the All Ranges of family and the connectivity of one or more network interface unit 32.Not only can realize the aggregate bandwidth of internal network 34 but also can realize internuncial upgrading, expansion by adding to insert or change to bigger hub.
As illustrated in fig. 1 and 2, the present invention separates the functional of network interface unit 32 and overhead electronic equipment 40.Conventionally, a top setting box comprises a network interface unit, and the parts of this network interface unit are connected internally to the overhead electronic equipment by a bus.Yet, in contrast, the invention provides network interface unit 32 and overhead electronic equipment 40 and put into separating of internal network 34 between the two.This arrangement allows a plurality of overhead electronic equipments to be distributed at lower cost in the family 36, and this is because needn't be the electronic equipment of each overhead electronic equipment duplicate network interface unit.In addition, make network interface unit 32 separately be connected to different external networks and a public internal network 34, can make the home owner needn't be from independent source, for example phone or wired radio station receive all programs (programming).This separation also allows home owner only just can increase, reduce or change service by changing one of them network interface 32, and does not need to reset all overhead electronic equipments 40 that spread all over family 36.
In certain embodiments, " master " top setting box has a plurality of network interface unit.Yet this embodiment because the network interface unit of this embodiment is connected to internal network, rather than is connected to overhead electronic equipment by bus logically with noted earlier identical.
Fig. 3 is the logic diagram of home network 10 of the present invention.From this figure obviously as can be seen, multiport switching hub 38 forms the center that network connects.In certain embodiments, wherein fully control the grouping jitter, adopt conventional, commercially available packet switching hub.At other preferred embodiments, as shown in Figure 3, switching hub 38 is networking ports and in the directly combination of the port of (circuit) conversion of session.Can lock direct connectivity port (and system) through network (coding) clock phase.For providing this functional, so switching hub 38 comprises simple and cheap relatively hub 42 and direct circuit (crossbar) 44 in length and breadth.In some preferred embodiment, hub 42 can be a commercially available equipment, for example by Sunnyvale, and the Am79C981 that the Advanced Micro Devices of Califbrnia makes.The direct circuit details of (crossbar) 44 is in length and breadth described in the back with reference to Fig. 7.
The star topology of Ethernet 10/100bas-T definition and switching hub 38 collaborative uses.Switching hub 38 is provided to the fan-out in a plurality of rooms in the dwelling house 36.Maximum system bandwidth is the multiple ((bit rate * port number)/2) of lead bit rate, and for example, 20 ports and 100Mbits/s bit rate=1Gb/s gather maximum bandwidth.
Switching hub 38 makes it possible to the extremely asymmetric traffic of special processing, for example compressed video data and internet data, and this is by directly they being routed to receiver from transmitter.This traffic is separated with internal network 34 like this, total and the aggregate bandwidth that makes only limit by the extensibility of hub 38, although total aggregate bandwidth is still limited by each 10Mbits/s of branch.Use the 100base-T technology to replace 10bse-T technology update system on demand.
Directly synchronously (Manchester or block encoding) connection of switching hub is mainly used in the MPEG video transmission that needs continuous, high bit rate, long duration to connect.The high bit rate video of compressed format can and be used for live video and action movie and physical culture up to 8Mbits/sec.Low-bit rate video is 1.5Mbits/sec.According to the present invention, the MPEG digital video is retained in whole network 10.Only occur to the conversion of real video at display device (for example, TV 12) or overhead electronic equipment 40.
Fig. 3 illustrates two kinds of direct circuits that separate as an example.For example, the network interface unit 32 that is connected to isdn network is by direct circuit 44 personal computers 20 that are directly connected to local perimeter network 15 in length and breadth.By another heterogeneous networks interface unit 32 (for example, being connected to hybrid fiber/ coax, HFC) with direct circuit 44 direct circuits that provide another to separate in length and breadth between the overhead electronic equipment 40 of TV 12 are provided.Not by direct circuit in length and breadth 44 direct-connected equipment remain and be connected to hub 42 and networking thus.
For the switching hub structure, wherein dispose a direct point-to-point path, all data of crossing this path are provided directly to the terminal point terminal in this path, even the data that are used for one or more other-ends also are like this.Like this, in some preferred embodiment, must follow a such rule, that is, must send to by the terminal point of directapath with the multiplexed data of high data rate (be generally message transmit) terminal that hub 38 is issued networking is returned in the grouping of crossing sample.For example, the message that is not used in the equipment on the local perimeter network 15 that sends at isdn network will turn back to the hub 38 that is used to distribute by local perimeter network main frame 20.This rule cost saving and by terminal point rather than central distribution go multiplexedly, reduce the complexity of switching hub, and be applicable to asymmetric data flow and local destination with group router type, that is, without multi-layer switcher.
Directly the advantage of transduction pathway is the potential delay of having avoided acquisition access network 34 (may make the meticulous clock reference sequential confusion that is loaded with in the mpeg data stream) fully.
In some preferred embodiment, hub 38 need be " full duplex consciousness (full-duplexaware) ", and its implication is that direct routed path only is connected to receiving terminal " descending " path with transmitter terminals " up " path.Otherwise the path that goes downwards to transmitter is not subjected to the influence of direct circuit and can normally be connected to network with the path that is up to receiver,, is connected to the residual terminal path of common connection that is.
Concrete route takes place in response user service request.Pick up message by hub control, and realize that any direct route changes.And the equipment that switches from network does not connect and does not need route.
As hereinafter described, carry out the MPEG clock recovery in network interface unit 32.By the MPEG clock recovery on the network interface unit 32, and the foundation of arriving the direct circuit of family network destination, the shake in the signal that receives in destination (for example, TV 12) can be eliminated substantially.The direct circuit function can be applicable to the extremely asymmetric point to point link amount in the amusement (video) under the home environment well.
For simple analog service, for example, the cable TV of transition, it is considered to not be the part of digital network.For the hybrid digital/analog service such as the new form of hybrid fiber/ coax, HFC (HFC) and mixing cable TV, it is considered to a transition state and it is treated to the temporary transient circumscribed annex of all digital systems of the present invention.Directly offer the combination of overhead electronic equipment 40 or network interface unit 32/ overhead electronic equipment 40 from the signal of hybrid fiber/ coax, HFC.Need two ports to be used for 32, one of network interface unit and to be used for overhead electronic equipment 40 to be connected to 10, one of home networks.Provide a bypass with the analog signal of link in certain embodiments through the audio/video circuit of overhead electronic equipment 40.
Through hand-held commander or computer keyboard, by in the local terminal, for example personal computer 20, or the software control home network 10 of overhead electronic equipment 40 operations.Specific to the Control Software of each home terminal by select with telecommunication management source availability, the source of network interface unit 32 and exterior gateway, path management.External network protocols is buffered in network interface unit 32 so that the terminal on home network 10 provides standard interface.Fig. 8 illustrates the example of a user interface.At this embodiment, home network 10 is transparent and the user only understands it indirectly from the quantity of service that is connected.
Fig. 4 illustrates an independent network interface unit 32 is connected to an independent overhead electronic equipment 40 by internal network 34 block diagram.For ease of showing and explaining, at the not shown remainder that comprises the home network 10 of conversion hub 38 of Fig. 4.
Structure supposition of the present invention, for some network, it is necessary for any bandwidth that remains on a definable bandwidth qualification (data flow) rather than set by the structure of input traffic (a plurality of data flow) that the first order on network interface unit 32 is gone multiplexed.Suppose and use the MPEG-2 video, exist from the diffluence of a plurality of programs transmission data to be multiplexed as an independent program transmission, defined as the MPEG-2 standard.This carries out by transmitting chip 54 such as the MPEG from the commercially available 9110B chip of C-Cube.(separately the multiplexed overhead electronic equipment that still occurs in is removed in the second level of video, audio frequency and other data, preferably only carries out decoding at display terminal or computer simultaneously).By this method, needn't only see the single program interface of a standard in the terminal in premises sends high-bandwidth data stream and family 36.For the video that produces in the family, for example, safe Qianmen video camera or video conference video camera need compression.
By Network Interface Module 50 carry out all external network interfaces, deciphering, access control, to a single program data stream go multiplexed etc.Like this, Network Interface Module 50 bufferings are from the home network hardware and software of the external network feature that is connected.A plurality of different programs need from one or a plurality of network interfaces of a plurality of suppliers connect in length and breadth.In certain embodiments, provide one to have, offer the program that receives from the same external network to the bimodulus piece of these two connections in length and breadth.
MPEG transmits chip 54 execution MPEG clock recoveries and the 27MHz clock that is recovered is provided to internal network with selected program and is connected 56.For example, when internal network 34 is the 10base-T Ethernet, the 27MHz clock is received network synthesizer 58 and is converted into the 10MHz clock by MPEG.The 10MHz clock, and selected program offers the transceiver (for example Ethernet transceiver) of the routine that is connected to internal network 34.Synthesizer 58 locks onto ethernet clock on the MPEG clock of recovery.When packet when network interface unit 32 sends to overhead electronic equipment 40, overhead electronic equipment 40 is locked into the mpeg data of the recovery of 27MHz clock.At overhead electronic equipment 40, by another synthesizer from Ethernet 10MHz clock regeneration 27MHz clock.
Receive data by the Network Interface Unit 62 that comprises network interface 64 at overhead electronic equipment 40.Reach " network to a MPEG " synthesizer 68 from the 10MHz clock of the data stream recovery of deviated from network 34 by gate circuit 66 by network interface 64.Need gating so that only when packet occurring, carry out lock function.The 10MHz clock is converted into the 27MHz clock that offers mpeg decoder 70 and video decoder/encoder 72.Selected program offers mpeg decoder 70 by network interface 64, and mpeg decoder 70 decoding mpeg datas also provide it to video decoder/encoder 72.Data flow is converted to the form (for example, NTSC or video) that is applicable to the display device such as TV by Video Decoder 72.Video Decoder is used for existing the NTSC analog signal will come the situation (HFC) of digitlization and merging with the graphic hardware in the plate.
Schematically provide the network 34 of Fig. 4, description by the front should be realized that video data can be placed on network 34 by hub 42, but propagate in length and breadth by the direct circuit of 44 network interface unit 32 and the non-jitter that overhead electronic equipment 40 preferably provides video data for the direct circuit by network 34.
Fig. 5 is the more detailed figure of example embodiment of the Network Interface Unit 62 of overhead electronic equipment 40 shown in Figure 4.Network interface unit 62 comprises the network synthesizer 68 that is connected to as the programmed logic device of gating device 66 work.Network synthesizer 68 can pass through commercially available chip, and for example the MC145151 of Motorola manufacturing realizes.Programmed logic device 66 can be passed through commercially available chip, and for example the MC7958 that is still made by Motorola realizes.VCXO 80 is operated in 27MHz and its signal is offered programmed logic device 62, and programmed logic device 62 offers synthesizer 68 with the 10MHz signal when having the packet that is received.Synthesizer is a public frequency that feeds back to the phase detectors of synthesizer 68 with 10MHz and 27MHz frequency division of the frequency.Provide the output of the phase detectors of synthesizer 68 to lock itself into input Ethernet frequency so that adjust local frequency up or down as the control signal of VCXO 80.
The signal and the 10MHz that provide notice programmed logic device 66 to receive packet by serial line interface adapter 82 enable as reception.The commercially available prod that is applicable to the serial line interface adapter is Am7992B, is made by Advanced Micro Device.
By a transformer/filter 84, for example be used for the commercially available PE68026 receiving data stream of Pulse Design.Also receive collision information by another transformer/filter 86, transformer/filter 86 can be same type with transformer/filter 84.To receive data and offer first network transceiver 88, the multiple twin Ethernet transceiver (AM79C100) that is for example added.The output of first network transceiver 88 (reception data) can be used for receiving and enables 82 and controller 90.Controller 90 can be a commercially available prod, for example monolithic ethernet controller Am79C970 (being made by Advanced Micro Device).Controller 90 is connected to bus 92, and peripheral component interconnect (pci) bus for example is used for the mpeg decoder 70 that the reception data of automatic network 34 in the future offer overhead electronic equipment 40.
Second network transceiver 92 is connected to controller 90, and can be by realizing with the transceiver of transceiver 88 same types.Second network transceiver 92 provides by the data transmit path of transformer/filter 84 slave controllers 90 to network 34.
Collision information is routed to controller 90 by the transformer/filter 86 and second transceiver 92.
Fig. 6 is that internal network connects 56 more detailed figure, and this internal network connects 56 and has " MPEG is to network " synthesizer 58 (seeing Fig. 4) that a 27MHz MPEG clock that recovers from MPEG transmission chip 54 synthesizes the 10MHz clock.Crystal oscillator 96 is connected to synthesizer 58 so that 10MHz to be provided signal.In certain embodiments, crystal oscillator 96 is 20MHz oscillators, and the frequency that is produced by synthesizer is 20MHz, follows at the simple frequency division of receiver (overhead electronic equipment 40) 20MHz quilt to 10MHz.A commercially available synthesizer is MC145145-2, is made by Motorola.
The 10MHz clock is offered Microprocessor Interface 98, and Microprocessor Interface 98 is as the interface of microprocessor 100.Microprocessor Interface 98 forms the transceiver 60 that is connected to internal network 34 by transformer/filter 102 with microprocessor 100.For example, Microprocessor Interface 98 can be the MC68160 chip of being made by Motorola, and microprocessor can be the MC68EN360 that is still made by Motorola.Transformer/filter 102 can be the transformer/filter with transformer/filter 84,86 same types of Fig. 5.
At preferred embodiment, overhead electronic equipment 40 is substantially as an appliance computer with audio frequency, video, figure and simulated television interface.For example the overhead electronic equipment provides home network special interface and necessary data buffering.It provides ethernet clock/MPEG clock lock at preferred embodiment.Overhead electronic equipment 40 decoding MPEG videos and audio frequency are to recover digital audio/video.It carries out the digital to analogy conversion of Voice ﹠ Video, and supports command forms and infrared remote control.Overhead electronic equipment 40 provides the support to analog video input (NTSC).Its interface printer, game port etc. support guiding (boot) level operating system also can download; Whole system forms an external network.Overhead electronic equipment 40 support application programs with by network interface unit communicating by letter to network provider and program video server.
To be hub 42 of the present invention 44 arrange and the more detailed block diagram of the example embodiment that is connected with overhead electronic equipment 40 with network interface unit 32 with direct circuit Fig. 7 in length and breadth.Direct circuit in length and breadth 44 and hub 42 connect for these unit provide direct circuit or the simple network by hub 42 between a particular network interface unit 32 and the overhead electronic equipment 40 selectively.At Fig. 7,, network interface unit 32 and overhead electronic equipment 40 parts only are shown for ease of expression and explanation.
In the preferred embodiments of the present invention, hub 42 is simple relatively and cheap, because it does not comprise grouping route switching or the storage and the forwarding exchange of any kind of.Do not resemble to exist the hub with grouping route switching yet and check the traffic and according to sending and receiver address dynamically switches the intelligence of hub.
Although at Fig. 7 a direct-connected network interface unit 32 and an overhead electronic equipment 40 only are shown, according to 44 size in length and breadth, the direct connection of any number is to can 44 connecting in length and breadth by direct circuit.Each all is shown having network interface unit 32 and overhead electronic equipment 40 5 pin positions or is connected, and each is connected to a pair of.This and routine call socket have the phone RJ45 unanimity of 10 pin positions.
Set up by a plurality of switches 108 that network between network interface unit 32 and the overhead electronic equipment 40 connects or the selection of direct circuit, switch 108 illustrates at Fig. 7, and its inferior makes its difference mutually in the following description.At the example of Fig. 7, network interface unit 32 directly is connected mutually with overhead electronic equipment 40, and network interface unit 32 sends data to overhead electronic equipment 40.44 controller and response need the position of the user command control switch 108 that direct circuit carries out to microprocessor 110 in length and breadth as direct circuit.For example, the user can select to watch film and carry out this selection by hand-held remote control thus from order video.Respond this selection, the position of microprocessor 110 by changing switch 108 is to set up the direct circuit between network interface unit 32 and the overhead electronic equipment 40, wherein network interface unit 32 is connected to the external network that is loaded with the order video service, and overhead electronic equipment 40 is connected to the television receiver that the user wishes to watch this film thereon.
In this case, switch 108a moves to shown position with the emission circuit of the transceiver 88 that connects network interface unit 32 and direct circuit 44 circuit 112 in length and breadth.The emission circuit of transceiver 88 no longer is connected to network at the Tx1 of hub 42 port.Similarly, the receiving lines of the transceiver 92 of overhead electronic equipment 40 is connected to direct circuit 44 same line 112 in length and breadth by switch 108g.By the direct circuit of present foundation, the data that enter family by network interface unit 32 are broadcasted on network without hub 42, are positioned at and will use the overhead electronic equipment 40 of the position of these data but directly offer.
Although direct circuit 44 direct circuits of setting up in length and breadth provides a good data path from network interface unit 32 to overhead electronic equipment 40, the data that may enter network interface unit 32 are not used for the situation of overhead electronic equipment 40 entirely.For example, might be through this particular network interface unit 32 receive E-mails, and the dwelling house owner wants this E-mail directly is dealt into personal computer, rather than TV.Yet,, do not have the connection of network 34 owing to set up a direct circuit.
For addressing this problem the routing function that the address of the packet of overhead electronic equipment 40 its receptions of inspection and execution are not used in the data of this overhead electronic equipment 40.These data are re-routed network 34 by overhead electronic equipment 40 by hub 42.Avoid making system to use expensive and complicated router by this rerouting that terminal point connection (the overhead electronic equipment 40 in this example) is carried out.Overhead electronic equipment 40 has microprocessor 120 and gets back to network 34 with relevant memory 122 with recognition data grouping and route.
In some preferred embodiment, a pair of picture-in-picture function that can be used for providing system in the 5 pairs of leads.For example, network interface unit 32 can provide through second pair and send lead by second data flow of another transceiver 88a to connection line in length and breadth 114 separately.Overhead electronic equipment 40 with another transceiver 88a that is also connected to circuit 114 receives its second data flow so that the picture-in-picture on the video screen to be provided by direct circuit.Like this, under the situation of non-jitter, provide two images by the direct circuit that separates.
In some preferred embodiment of the present invention, the signal controlling of response controller 110 realizes crossbar switch 108 by a simulation mos transistor array.Yet this only is exemplary, and is appreciable as those of ordinary skills, and other embodiment can adopt the switch of different designs.
Although specification of the present invention is described definite logic function feature of each parts, these logical implications can be different at other embodiment.For example, hub 42 is described as being connected to internal network.Yet hub 42 can also logically be considered to the part of internal network, even constitutes this network, and all the other lines form the device that terminal is connected to hub 42.Therefore, those of ordinary skills can see described in the specification of the present invention and the logical implication that illustrates only is exemplary.
According to the present invention network interface unit with provide separating of overhead electronic equipment a plurality of equipment in the family mutually and to relatively inexpensive being connected in the external world.
Although described the present invention in detail, should be understood that given only conduct description and example, do not have qualification, the spirit and scope of the present invention limit by the appended claims book.
Claims (14)
1. one kind is used for the method for distributing the MPEG clock on the internal network by the data stream recovery MPEG clock that receives from external network, comprises step:
In network interface unit, recover the relevant clock of MPEG by the mpeg data stream that receives from external network;
Use is arranged in the MPEG transmission chip of network interface unit and selects a program from stream;
The relevant clock of MPEG that this machine clock is directly locked onto recovery provides internal clocking with the internal network to the relevant clock of the MPEG that is locked into described recovery;
Mpeg data according to internal clocking automatic network interface unit in future transmits on internal network;
In being connected to the overhead electronic equipment of internal network, synthesize the MPEG clock according to internal clocking by the mpeg data that on internal network, transmits.
2. the method for claim 1, wherein internal network is an Ethernet, the MPEG clock is 27MHz and this machine clock is 10MHz.
3. the method for claim 1, wherein the step of synthetic MPEG clock comprises that the signal that internal clocking and expression are received mpeg data offers frequency synthesizer.
4. the method for claim 1, wherein the step of synthetic MPEG clock comprise signal that only response expression receives mpeg data with synthetic MPEG clock lock to the data of overhead electronic equipment through the internal network reception.
5. one kind is recovered the device of MPEG clock from mpeg data stream, comprising:
Network interface unit is used for receiving mpeg data stream and mpeg data being sent to predetermined overhead electronic equipment from external network,
This network interface unit has: the MPEG clock recovery circuitry that is used for recovering from mpeg data stream the MPEG clock, be used for selecting the MPEG transmission chip of a program from data flow, and the frequency synthesizer that is used for internal clocking is locked onto the MPEG clock of recovery;
Described predetermined overhead electronic equipment has a frequency synthesizer, is used for synthesizing the MPEG clock by the mpeg data according to internal clocking clock synchronization on internal network.
6. device as claimed in claim 5, wherein internal network comprises a plurality of overhead electronic equipments, comprise described predetermined overhead electronic equipment, and one connects described network interface unit and the switching hub with at least one described predetermined overhead electronic equipment of described second frequency synthesizer;
Described switching hub comprises that being used to connect described network interface unit is connected with the direct of described predetermined overhead electronic equipment synchronously, be used for from described network interface unit to the described described mpeg data of predetermined overhead electronic equipment so that at the synthetic described MPEG clock of described predetermined overhead electronic equipment
Therefore avoid the delay of accesses network and upset the included clock reference of described mpeg data stream regularly.
7. the method for claim 1, wherein said transmitting step comprises step:
Between network interface unit and overhead electronic equipment, provide one directly to connect synchronously; With
By using direct the connection synchronously that mpeg data is sent to the overhead electronic equipment, avoid the delay of accesses network and upset the included clock timing of mpeg data stream that receives.
8. method of recovering and distributing the MPEG clock from mpeg data stream comprises:
Recover the relevant clock of MPEG in the network interface unit that is connected to an external network from the mpeg data stream that receives;
Use is positioned at the MPEG transmission chip of network interface unit and selects a program from data flow;
This machine clock is directly locked onto the relevant clock of MPEG of recovery so that an internal clocking to be provided;
Mpeg data according to this internal clocking automatic network interface unit in future sends to the overhead electronic equipment that is connected to internal network; With
Synthesize the MPEG clock at the overhead electronic equipment that is connected to internal network from mpeg data and internal clocking.
9. method as claimed in claim 8, wherein said forwarding step comprises step:
Between network interface unit and overhead electronic equipment, provide one directly to connect synchronously; With
By using direct the connection synchronously that mpeg data is sent to the overhead electronic equipment, avoid visiting the delay of internal network and upset the included clock timing of mpeg data stream that receives.
10. the method for claim 1, wherein the step of synthetic MPEG clock comprises that the internal clocking of the relevant clock of MPEG that will lock onto described recovery offers frequency synthesizer; With
Comprise further step: use described internal clocking adjusting a local oscillator signal, thereby provide from corresponding to described MPEG clock and be locked into the output signal of described frequency synthesizer of the relevant clock of MPEG of described recovery corresponding to described MPEG clock.
11. method as claimed in claim 3, comprise further step: described internal clocking is offered the MPEG synthesizer, local oscillator signal is offered the MPEG synthesizer, and adjust described local oscillator signal, thereby provide output signal from the described MPEG synthesizer of the relevant clock of the MPEG that is locked into described recovery according to the described signal that described internal clocking and expression receive mpeg data.
12. method as claimed in claim 3, comprise further step: the described signal that uses expression to receive mpeg data when receiving mpeg data is strobed into the MPEG synchronizer with described internal clocking, the internal clocking of described gating is offered the MPEG synthesizer, to offer the MPEG synthesizer corresponding to the local oscillator signal of MPEG clock, and adjust described local oscillator signal, thereby provide the comfortable output signal that is locked into the described MPEG synthesizer of described internal clocking when receiving described mpeg data according to the internal clocking of described gating.
13. device as claimed in claim 5, wherein connect described second frequency synthesizer with the internal clocking that is used to receive the MPEG clock that is locked into described recovery and
Further comprise a generation corresponding to the local oscillator of the local oscillator signal of described MPEG clock be used to use described internal clocking to adjust described local oscillator adjusting the device of the local oscillator signal that is produced, thereby provide from corresponding to described MPEG clock and be locked into the output signal of described second frequency synthesizer of the relevant clock of MPEG of described recovery.
14. device as claimed in claim 13 further comprises:
Provide to described second frequency synthesizer the mpeg data that expression receives by described predetermined overhead electronic equipment through internal network signal device and
The described signal that receives mpeg data when response expression is used for internal clocking is strobed into the device of described second frequency synthesizer when receiving mpeg data,
Thereby provide from the output signal that when receiving described mpeg data, is locked into the described second frequency synthesizer of described internal clocking.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 00108623 CN1311587A (en) | 2000-02-26 | 2000-02-26 | Method and device used for data flow clock |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 00108623 CN1311587A (en) | 2000-02-26 | 2000-02-26 | Method and device used for data flow clock |
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| CN1311587A true CN1311587A (en) | 2001-09-05 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN 00108623 Pending CN1311587A (en) | 2000-02-26 | 2000-02-26 | Method and device used for data flow clock |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105790872A (en) * | 2014-12-26 | 2016-07-20 | 中兴通讯股份有限公司 | Network clock synchronization device and working method of the network clock synchronization device |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105790872A (en) * | 2014-12-26 | 2016-07-20 | 中兴通讯股份有限公司 | Network clock synchronization device and working method of the network clock synchronization device |
| CN105790872B (en) * | 2014-12-26 | 2019-01-29 | 中兴通讯股份有限公司 | A kind of network clock synchronous device and its working method |
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