System and method for transmitting a plurality of digital services including imaging services

We claim:

1. In a receiver for receiving digital data streams transmitted in a frame format comprising rows and columns, the first row of the frame comprising a horizontal synchronization word followed by a vertical synchronization word, apparatus for decoding the horizontal synchronizing word comprising

means for storing the identity of predetermined respective locations of block synchronization data and other data of a horizontal synchronization word,

means for recovering the horizontal synchronization word,

means for extracting the other data at the predetermined locations and

means for forming a data stream from the extracted other data.

2. The apparatus of claim 1 wherein the horizontal synchronization word is binary comprising alternating values.

3. The apparatus of claim 2 wherein the horizontal synchronization word comprises one eight bit byte and the block synchronization data and other data each comprise four bits.

4. The apparatus of claim 1 wherein the means for recovering the horizontal synchronization word comprises frequency comparison means.

5. The apparatus of claim 1 wherein the means for recovering the horizontal synchronization word comprises means for comparing the block synchronization data with a predetermined binary pattern.

6. The apparatus of claim 1 wherein the predetermined bit positions of the other data are in predetermined sequence and the other data comprises network signaling data.

7. Apparatus for decoding a horizontal synchronizing word according to claim 1, said data stream forming means for extracting at least one bit of other data per frame and combining a plurality of said at least one bit received over at least two frames into said data stream.

8. Apparatus for decoding a horizontal synchronizing word according to claim 1, further including means, responsive to said data stream of said data stream forming means from the extracted other data, for interpreting said data stream as at least one of network signalling, telecommunications identification, transmitter identification, logical connector order, maintenance, and alarm information.

9. Apparatus for decoding the horizontal synchronizing word according to claim 7, further including means, responsive to said data stream of said data stream forming means, for interpreting said data stream as at least one of network signalling, telecommunications identification, transmitter identification, logical connector order, maintenance, and alarm information.

10. In a receiver for receiving digital data streams transmitted in a frame format comprising rows and columns, the first row of the frame comprising a horizontal synchronization word followed by a vertical synchronization word, a method for decoding the horizontal synchronizing word comprising the steps of

storing the identity of predetermined locations of block synchronization and other data of a horizontal synchronization word,

recovering the horizontal synchronization word,

extracting the other data at the predetermined locations and

forming a data stream from the extracted other data.

11. The method of claim 10 wherein the block synchronization data is binary comprising alternating one and zero values.

12. The method of claim 11 wherein the horizontal synchronization word comprises one eight bit byte and block synchronization and the other data each comprise four bits.

13. The method of claim 10 wherein the step for recovering the horizontal synchronization word comprises comparison with a predetermined frequency represented by the horizontal synchronization word.

14. The method of claim 10 wherein the step for recovering the horizontal synchronization word comprises comparing the horizontal synchronization word with a predetermined pattern.

15. The method of claim 10 wherein the predetermined bit positions of the other data are in predetermined sequence and the other data comprises network signaling data.

16. The method for decoding the horizontal synchronizing word according to claim 10, said step of forming a data stream from the extracted other data including the step of extracting at least one bit of other data per frame and combining a plurality of said at least one bit received over at least two frames into said data stream.

17. The method for decoding the horizontal synchronizing word according to claim 10, further including the step of interpreting said data stream as at least one of network signalling, telecommunications identification, transmitter identification, logical connector order, maintenance, and alarm information.

18. In a receiver for receiving digital data streams transmitted in a frame format comprising rows and columns, the first row of the frame comprising a horizontal synchronization word immediately followed by a vertical synchronization word, the vertical synchronization word immediately followed by a multiplex structure control word, wherein the frame comprises PACKETS data of different types determined by the number of bytes in a particular type of packet and the multiplex structure control word comprises data representing the number of packets of a particular type, and end of data markers for the digital data streams, apparatus for decoding the multiplex structure control word comprising

synchronization recovery means for recovering horizontal and vertical synchronization for the frame and

demultiplexer means, responsive to the synchronization recovery means, for demultiplexing the digital data streams in accordance with the multiplex structure control word said demultiplexer means including counters for determining the end of each received stream from said multiplex structure control word.

19. The apparatus for decoding the multiplex structure control word according to claim 18, said demultiplexer means outputting at least one of an error flag, data, clock, and enable signals.

20. The apparatus for decoding the multiplex structure control word according to claim 18, said demultiplexer means controlling in accordance with said multiplex structure control word at least one of a video processor, an audio processor, a text processor, and a low speed data processor.

21. The apparatus for decoding the multiplex structure control word according to claim 18, further including an expansion socket receiving at least one of data, an error flag, a clock signal, and a frame synchronization signal.

22. In a receiver for receiving digital data streams transmitted in a frame format comprising rows and columns, the first row of the frame comprising a horizontal synchronization word immediately followed by a vertical synchronization word, the vertical synchronization word immediately followed by a multiplex structure control word, apparatus for recovering the low speed data comprising

synchronization recovery means for recovering horizontal and vertical synchronization for the frame,

demultiplexer means, responsive to the synchronization recovery means, for demultiplexing the low speed data from the low speed data packets in accordance with the multiplex structure control word,

a low speed data processor for processing low speed data packets, the low speed data processor comprising a stripping means for stripping header data from the received packet and a data reformatter for reformatting the data into an originally input format, and

buffer memory wherein the data reformatter outputs data from the buffer memory in data bursts at a faster rate than the data is stored in the buffer memory.

23. The apparatus of claim 22 wherein the low speed data processor decodes rata trim data of the header.

24. The apparatus of claim 22 wherein the low speed data processor decodes baud rate data of the header.

25. The apparatus for recovering the low speed data according to claim 22, said frame format further including high speed data packets containing high speed data, said demultiplexing means further including means for demultiplexing the high speed data from the high speed data packets in accordance with the multiplex structure control word.

26. In receiver apparatus for receiving a signal including high speed data streams, the high speed data stream including at least a digital television data stream, a high speed data processor comprising

decoder means for decoding a packet data portion of the received signal including a high definition television signal flag,

first output means, responsive to said decoder means, for outputting a received television signal, and

second output means, responsive to said decoder means, for outputting a high definition television signal indicator signal when the output television signal is a high definition television signal.

27. The high speed data processor according to claim 26, wherein said decoder means outputs at least one of data, an error flag, a clock signal, and a frame synchronization signal and said first output means receives said at least one of data, an error flag, a clock signal, and a frame synchronization signal.

28. The high speed data processor according to claim 27, further receiving an audio data stream and including an audio processor for responding to said audio data stream and said at least one of data, an error flag, a clock signal, and a frame synchronization signal and for outputing an audio signal.

29. The high speed data processor according to claim 27, further receiving a text data stream and including a text processor for responding to said text data stream and said at least one of data, an error flag, a clock signal, and a frame synchronization signal and for outputing a text signal.

30. The high speed data processor according to claim 27, further receiving a low speed data stream and including a low speed data processor for responding to said low speed data stream and said at least one of data, an error flag, a clock signal, and a frame synchronization signal and outputs a low speed data signal.

31. The high speed data processor according to claim 26, further including an expansion socket receiving said at least one of data, an error flag, a clock signal, and a frame synchronization signal.

Description Submit all comments and votes

This application is related by subject matter to U.S. application Ser. No. 160,828, entitled "System and Method for Transmitting a Plurality of Digital Services Including Compressed Imaging Services and Associated Ancillary Data Services" U.S. Ser. No. 160,811, entitled "Memory Efficient Method and Apparatus for Synch Detection", Ser. No. 161,159 entitled "A Multi-Service Data Receiver Architecture", Ser. No. 160,830, entitled "System and Method for Transmitting and Receiving Variable Length Authorization Control for Digital Services", Ser. No. 160,827, entitled "System and Method for Providing Compressed Digital Teletext Services and Teletext Support Services", Ser. No. 160,848, entitled "System and Method for Simultaneously Authorizing Multiple Virtual Channels", and Ser. No. 160,839, entitled "Method and Apparatus for Locating and Tracking a QPSK Carrier" filed concurrently herewith.

I. BACKGROUND OF THE INVENTION

A. Field of the Invention

The present invention relates generally to digital signal transmission, and more particularly, to a system and method for multiplexing a plurality of digital services, including imaging services, for transmission to a plurality of remote locations.

B. Description of the Relevant Art

With the growing trend toward a merger of the previously separate technologies of telecommunications including voice and data telecommunications and television including satellite, broadcast and cable television, there has emerged an increased interest in developing adaptable transmission systems capable of handling any one or more of a collection or plurality of such services. The primary media investigated for providing such services to date comprise, For example, coaxial cable, land-based microwave, so-called cellular radio, broadcast FM, broadcast satellite and optical fiber, to name a few.

Each media has its own characteristics. For example, comparing cable and satellite for digital data transmission, cable tends to have a medium error rate, but, when errors appear, the errors come in long bursts. Satellite as a media has a pretty poor error rate, primarily due to the requisite weak signal power, and hence, low signal to noise ratio. In satellite, then, the poor error rate is specially corrected utilizing such techniques as convolutional error correctors, not required in a cable environment.

In copending U.S. application Ser. No. 07/968,846 filed Oct. 30, 1992 and entitled "System and Method for Transmitting a Plurality of Digital Services," there is described an encoder for generating a multiplexed data stream carrying services to remote locations via, for example, a satellite or a cable distribution network. The generated data stream comprises a continuous sequence of frames, each frame comprising two fields, and each field comprising a plurality of lines. A first group of lines of a field defines a transport layer and a second group of lines defines a service data region. A feature of the disclosed scheme is the ability to dynamically vary the multiplexed data stream from field to field. A further feature of the disclosed scheme is that the data transmission rate of the multiplexed data stream is related to the frequency of known analog video formats, i.e. frame, field and horizontal line rates.

In copending U.S. application Ser. No. 07/970,918 filed Nov. 2, 1992, entitled "System and Method for Multiplexing a Plurality of Digital Program Services for Transmission to Remote Locations," there is described another system, this for multiplexing a plurality of digital program services comprising a collection of, for example, video, audio, teletext, closed-captioning and "other data" services. According to the disclosed scheme, a plurality of subframe data streams are generated, each having a transport layer region and a program data region. These subframe data streams are then multiplexed together into superframes having a transport layer region and a subframe data region.

While these disclosed transmission systems permit a variety of services to be transmitted over various media to remote locations, there remains a need to provide yet other alternative arrangements more particularly adapted to the wide variety of services that may be offered over various media and permit the end user at the remote location greater flexibility over the data content the user is ultimately enabled to receive. Moreover, such a system should be able to be easily adapted to transmit an increasing number of different services in an increasingly efficient manner, for example, utilizing the same or less bandwidth.

Since such services as high definition color television services, so-called "surround-sound" digital audio services, interactive transactional services for home-shopping, reservations, first-run as well as classic movie programming, software delivery, interactive game, alarm services, energy management and such all involve different bandwidths, data formats and such, there remains a need for flexibility in the overall structure provided for transmitting such services. Moreover, a user should not be presented with an overwhelming number of choices, but should be able, in a user-friendly manner, to select only those services which he is capable of receiving or wants to receive. Ideally, the user should be able to have access to an infinite variety of data services, selectable as he chooses, so that he may, for example, watch a first run movie in so-called high definition accompanied by a "surround-sound" audio in the language of his choice and, at the same time, receive a facsimile or voice communication over the same media. If the user is equipment-limited, for example, to a standard resolution television and a telephone set, the user should be able to fashion the delivery of services to the equipment he owns.

II. SUMMARY OF THE INVENTION

Briefly stated, the present invention is directed to a system and method for multiplexing a plurality of digital service data streams at varying data rates and transmitting the services from an origination point to a plurality of remote locations. A digital service may comprise a collection selectable by the user from any of a number of low data rate, medium data rate and high data rate services including, but not limited to, video (both standard and high resolution), audio (from monaural to "surround-sound"), and data (from subscription software to video games to high speed data-base exchanges).

The present invention is described primarily in the context of a pay television system such as a cable television or direct broadcast satellite system (DBS), that typically distribute a variety of program services to subscribers for presentation on home terminal equipment which is the property of the end user or subscriber to the pay services. Such home terminal equipment may comprise video game apparatus, a television signal receiver (either standard or high definition), a home computer, a printer (either a facsimile or high resolution image printer), a stereo sound system, a telephone (including portable, mobile or stationary), a picture-phone, an energy system or alarm equipment interface, or any other known such apparatus or combination of apparatus. Consequently, the present invention does not only envision the environment of the present invention to be so limited but may also include the telecommunications environment or other fixed or switched one-way or two-way program apparatus. It will be assumed, however, that such services be converted, if not already in digital form, to digital form for transmission over the present system.

A method for transmitting a plurality of digital services including low speed data services, medium speed data services and high speed data services comprises the steps of removing parity, start and stop data from low speed digital data, compressing medium and high speed digital data streams, generating packets data comprising predetermined header data, the packets data including at least a multiplex structure control word and low speed data, forming a data frame comprising rows and columns, the frame formed in accordance with the sequence of packets data including low speed data, medium speed data and high speed data, adding block-coded forward error correction data as necessary with the choice of medium, interleaving the frame by rows and columns and inserting horizontal row (block) and vertical column (frame) synchronization words.

Moreover, the horizontal or block synchronization word, hereinafter referred to as BLOCK SYNC, may comprise from four to eight bits for synchronization and substitute, therein, from zero to four bits of network signalling data at predetermined bit positions in the word. For example, if the horizontal synchronization word is binary and comprises eight bits of alternating one and zero values, then, the network signalling data may comprise four bits at predetermined bit positions, for example, the final four bit positions. In an alternative embodiment, the four bits of network signalling data may be located in a predetermined sequence of bit positions, for example, at even or odd-numbered bit positions of the eight bit synch word.

A multiplex structure control (MSC) word precedes the packets data and comprises counter data for a receiver according to the present invention. Included within the MSC word are an end of packets marker, an end of medium speed data marker and an end of high speed data marker. The MSC word is the first word of the interleaved frame and immediately follows the vertical or frame synchronization word, hereinafter referred to as FRAME SYNC.

Consequently, the present invention permits the transmission of a plurality of services including compressed data streams such as per ISO 11171 or ISO 13818 M.P.E.G. compression standards and low speed data streams efficiently over limited bandwidth and in noisy, error-prone environments. Other features and advantages of the present invention will be more particularly described in the following description of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a system block diagram showing a transmitter site 100 including an encoder and a receiver site 150 including a decoder according to the present invention for transmitting low data rate, medium data rate (audio) and high data rate (video) data implemented in a satellite communications system.

FIG. 2a is a diagram showing a scalable multiplex frame, including synchronization words BLOCK SYNC and FRAME SYNC, for transmitting a digital data stream of low data rate (included within PACKETS), medium data rate (audio) and high data rate (video) data protected by Reed-Solomon encoding according to the present invention.

FIG. 2b is a second diagram of the frame of FIG. 2a wherein the PACKETS area is further broken down into first and second regions, the first region including packets with extra error protection and the second region including data protected only by Reed-Solomon encoding.

FIG. 2c is a diagram showing that a sequence of frames in the form of FIGS. 2a or 2b are transmitted to a receiver according to the present invention.

FIGS. 2d(1) and 2d(2) provide alternative embodiments of a one byte horizontal synchronization (BLOCK SYNC) word which may include both synchronization and network signaling data bits therein.

FIG. 3 is an encoder block diagram for one preferred embodiment of a portion of transmitter 100 of FIG. 1 showing the connection of audio and video compressors and low speed data formatters to a multiplexer under control of a control computer for modulation by a modulator on to a carrier for transmission, for example, by satellite as shown in FIG. 1.

FIG. 4 is a detailed schematic block diagram of a multiplexer 110 of FIGS. 1 or 3 according to the present invention for outputing multiplexed data according to the multiplex frame format of FIGS. 2a, 2b and 2c.

FIG. 5 is a detailed block diagram of a portion of receiver 150 of FIG. 1 showing tuner/demodulator 154 and clock and data recovery 155 in greater detail.

FIG. 6a is a detailed block diagram of a preferred demultiplexer arrangement, the demultiplexer being responsive to synch and clock recovery accomplished via FIG. 5 and outputing data, clock and error flags on a bus 610 to data processors for low speed, medium speed and high speed data streams; FIG. 6b shows detail of low speed data processor 622 of FIG. 6a; and FIG. 6c shows a typical low speed data packet.

FIG. 7a shows a redundant configuration wherein the multiplexer functions are duplicated such that if a particular multiplexer fails for one reason or another, control may be transferred to the redundant multiplexer.

FIG. 7b shows a configuration wherein there may exist a plurality of multiplexed services for transmission via modulator of FIG. 3 all under control of a single shared control computer wherein the modulator comprises a QPSK modulator and the data streams for the services are combined as the I and Q inputs to the modulator for upconversion to cable or satellite frequencies.