INTERACTIVE SATELLITE BROADCAST SYSTEM

Abstract: In a method of providing an interactive broadcast service, broadcast signals are transmitted via a wideband satellite link to end users. Return signals are received from the users transmitted over a narrowband satellite link separate from the first link. The return signals allow users of the service to send commands back to the base station to request specific services.

Description: INTERACTIVE SATELLITE BROADCAST SYSTEM This invention relates generally to a satellite communications system providing interactive services to end users. Direct Broadcast Satellite DBS systems, where service providers broadcast direct to small receiving dishes in the home, are well known. Initially, these were one-way services allowing purely passive reception. More recently, telephone operating companies have started providing a return line through a terrestrial line to accommodate a user retum capability for services such as pay per view TV, home shopping, home banking and similar other services; HUGHES DirectTV presently uses a POTS line as a retum to carry information relating to the billing of services provided. This solution requires the use of the switched telephone network and is inefficient, especially when it is used to carry small amounts of data such as ordering information and the like. Some DBS services offer access to the Internet with the downstream data being provided via satellite on a wideband channel and the retum path being via a narrow band terrestrial link, usually a conventional POTS telephone line. This arrangement requires a switched telephone circuit and ties up the public switched network even though relatively small amounts of data are transmitted on the retum link on an occasional basis. An object of the invention is to provide an improved interactive direct broadcast system. According to one aspect of the present invention there is provided an interactive direct broadcast station comprising means for transmitting broadcast signals via satellite to an end user over a wideband satellite link, means for receiving retum signals from end users over a separate narrow band satellite retum link providing a retum path, and means for interpreting said retum signals to respond to requests from the end user. The broadcast signals can be conventional broadcast video signals or multimedia signals from the comprising text, graphics, sound and video. The Internet is an example of a source of multimedia signals. A wideband link is of the type suitable for broadcast purposes, such as the Ku- band allocated for satellite service. A narrowband link is of the type more usually associated with mobile communications, such as the L-band. The forward broadcast signals are preferably carried in the Ku band, with the retum command signals being carried in the L-band, which is typically used for mobile communications. The invention thus combines two, different one-way satellite transmissions using two different satellites. In a preferred embodiment, this invention uses an L-band satellite proximate to the Ku band broadcast satellite to provide a low cost retum path from an individual subscriber. It is estimated that up to a million transactions per hour on the L-band satellite can be provided with each 300 kHz circuit. Currently set top boxes on the user premises have a one way path from a satellite dish that allows a receive only function. This invention thus provides an inexpensive narrow band transmitter to the system which provides a low cost retum. It is estimated that the cost ofa single transaction is a small fraction of the cost ofa transaction using POTS. The associated cost using an L-band satellite for low rate data transmission is less than the cost of using Ku-band satellites for high speed retum data transmission; L-band transmitters can be at low cost incorporating a low signal level with an antenna having low gain; L-band systems are coordinated to cope with low level wide beam broadcast signals, thus adjacent satellite interference problems can be overcome. In a preferred embodiment of this invention CDMA (Code division Multiple Access) is used to ensure a lowest possible RF transmit level for a quantity of information that is transmitted on the retum link, thereby providing retum capacity at low cost. The invention provides a new combination of the receiver and transmitter with CDMA L-band operating simultaneously in conjunction with a broadcast signal in the Ku band. A specific and preferred embodiment of this invention relates to its applicability to existing home satellite dishes that can be adapted at a low cost to conform with the teachings of this invention. The system includes a narrow beam accurately directed Ku-band antenna (currently present in DBS systems), and in accordance with this invention a second low gain wide-beam L-band antenna. The L-band antenna may be independent of the narrow beam antenna, or it may be incoφorated with the DBS antenna, using the dish or a reflector. The latter embodiment produces a very wide beam at L-band because the reflector is small in terms of L-band wavelengths. which preferably can be mounted in conjunction with the narrow beam antenna, preferably on the same dish, for example, near its periphery because the L-band antenna does not make use of the focussing characteristics of the dish and does not have to be pointed accurately. Alternatively, the L-band antenna may be independent of the Ku-band antenna. It may be mounted on the periphery of the Ku-band dish or alternatively, remote from it in the form of a microstrip patch or short helix of several turns providing suitable, relatively low gain for this application. This invention combines the advantages of satellite mobile communications in the L-band with the advantages of the broadcasting capabilities of the Ku band. The system provides a high data rate broadcast signal out (on the Ku band) and a low data rate retum signal (on the L-Band), Furthermore, this can be achieved with existing satellites. Another novel and inventive aspect of this invention lies in the arrangement of components disposed between a set top-box and the antenna units. Essentially these components comprise a CDMA module providing modulation of the L-band retum signal. This module further includes a Tx unit for the L-band. According to another aspect of the invention there is provided a home direct broadcast receiving system, comprising a receiver for receiving wideband broadcast signals from a hub station via satellite on a wideband link, means for generating retum signals for making specific requests to said hub station, and a transmitter for transmitting said retum signals via satellite back to said base station over a separate narrowband link. According to a still further aspect of the invention there is provided a method of providing an interactive broadcast service comprising the steps of transmitting broadcast signals via a wideband satellite link to end users, receiving retum signals from said users transmitted over a separate narrowband satellite link, and responding to said retum signals to provide services requested by said users. The invention thus provides a communications system that comprises two different satellites each configured to operate to form a single communications system wherein each satellite is are in one-way communications but together, provide two way communications. More specifically, an aspect of the invention relates to terminal equipment on the user premises, comprising a small low cost transmitter in a retum link in the system. The invention will now be described in more detail, by way of example, only with reference to the accompanying drawings, in which: - Figure 1 is general diagram of an interactive satellite broadcast system in accordance with the invention; Figure 2 is a block diagram of a hub station in accordance with the invention; Figure 3 is a block diagram ofa DTH/DBS terminal enhanced with a narrowband retum link; and Figure 4 is a block diagram showing the necessary additions to the set-top controller software. The system in accordance with this invention is illustrated in Figure 1. The system makes combined use of two satellite systems both operating in a one-way mode. The forward link 1 is a direct broadcasting/direct-to-home satellite system, inherently a one-way system, broadcasting to several million users. The bulk of broadcast services comprise entertainment video services, which include pay-per view and impulse pay-per-view television. Both of the latter may make use ofa very low capacity return link 2 to order particular services or to convey the information that particular services were used. A wide variety of infotainment services which also require a low capacity retum link may also be provided. Examples are home shopping, financial services, video auctions, horse race betting, video casinos, travel arrangements, opinion polling, game shows etc. The retum link 2 is provided through the one-way use ofan L-band, geostationary orbit, mobile satellite system 3. Since only a very low capacity is required in the retum link, the transmitter uses Code Division Multiple access technology, which results in a low cost and is ideally suited to this application because most transactions on the return path involve bursts of relatively small amounts of data. From 100 to 200 bits are sufficient for most transactions, and transmission rate is nominally in the range of 1200 to 4800 bps. The L-band link is designed to permit typically 400 messages per second per circuit. In Figure 1, the hub 4 has feeds from various services, such as from a DBS service provider, home shopping service provider, and financial service provider and broadcasts these from conventional satellite broadcast transmitter 5 via a channel on the Ku band satellite 6 to home users, such as 7. Each home user includes a Ku band receiving antenna 8, a combined L-band TX/Ku-band RX unit 9, and a set-top unit 10 connected to a television 11. The set-top unit 10 may be controlled by a wireless remote control unit 12 in a conventional manner. In operation, a typical user 7 can select a broadcast channel using his remote unit 12 in a conventional manner. In addition, the user can request specific services, for example, pay-per-view movies by entering appropriate codes into the remote unit 11. These are then transmitted on the L-band link back to the hub 4 using CDMA techniques. The hub 1 1 can then respond by, for example, enabling the users address on the broadcast channel so as to grant access to a requested movie. The retum link can also be used to transmit ordering information for home shopping services, or instructions to the financial services provider to carry out certain transactions. The primary characteristic of the data on the retum link 2 is that it very low bandwidth compared to the broadcast signals since it in essence consists of commands from the user related to the broadcast signals. Congestion control techniques can be implemented to provide the availability required by the individual application, typically 99.9%, but higher if required. The cost of the L-band transmit unit should be US$100 or less. Referring now to Figure 2, the primary elements embodied in the uplink and downlink hub earth stations are shown, including the principal interfaces. Existing DTH/DBS uplink 20 and mobile satellite feederlink earth stations 30 are used, with the addition ofa number of elements to facilitate the low cost satellite retum link system. The uplink unit 20 comprises a archived video server 21 for storing movies and the like, and a real-time coder 22 receiving signals from a DTH/DBS service provider and coding them so as to allow reception only by authorized users. The output of the coder 21 along with the output of the video server 21 is fed to multiplex and formatting unit 23, which formats the signals for broadcast over the Ku-band satellite link 1 from antenna 27 after passing through forward error correcting unit 24, modem 25, and Ku-band Tx unit 26. The retum signals in the L-band are received by the mobile satellite feeder link receiving antenna 31 and passed through feeder unit 32 to CDMA demodulator 41 in interface unit 40. After CDMA demodulation , the signals are passed through forward error correction unit 42 to recover errors and from there to application interface processor 43. The application interface processor 43 receives these signals and either passes them through to the retum network controller 44, which interfaces with the network control system 45 in the uplink unit 20 or else passes them to the appropriate third party providers, such as financial services providers and the like. The signals from the FEC unit 42 are also fed to the network Performance Monitoring Processor 45, which feeds the Retum Network Controller 44. This controls the retum terminal transmission using a suitable congestion control strategy to ensure that signal loss does not exceed the availability specification. The DTH/DBS 50 receiver is shown in Figure 3. The set-top unit 50 deals with both applications related data being transmitted and network control data generated by the Retum Network Controller 44 at the hub station. Typical set-top units are the Star Trak 1000, DSS model 4430, and Power Vu Model D9223 digital satellite receivers manufactured respectively by Tee-Comm, RCA, and Scientific Atlanta. Ku-band antenna 51 feeds signals to low noise receiver 52, which forwards them in turn to demodulator 53, FEC decoder 54, MPEG demultiplexer 55, and decrypter 56, which passes only signals authorized for the user. From the decrypter 56, the signals are passed to the MPEG video decoder 57, the MPEG audio decoder 58, and data interface unit 59. Units 57 to 59 are connect to PAL or NTSC encoder 60, for connection to a television, and a PC to provide, for example, wideband downstream access to the Intemet. The set top unit 50 is controlled by wireless remote 61 communicating with a wireless interface unit 62 connected to set top controller 63. The block 50 as described so far is conventional. However, the set-top controller 63 is modified to incorporate software to deal with applications using the return link capability described herein. Specifically the additional software formats and generates the return link signal passed to forward error correcting encoder 71. In accordance with this embodiment of the invention, the set top controller 63 is also connected to a forward error correcting encoder 71, a CDMA modulator 72, and an L-band transmit unit 73. This in turn feeds an L-band antenna 74, which is in close proximity to the Ku-band antenna 51 , for onward transmission to the separate L-band satellite, which is generally close to the Ku-band antenna. Downstream signals are received in a conventional manner. Applications data is encoded and modulated for transmission upstream by the low power L-band transmitter 73 via the mobile satellite used. Actual transmission timing is under control of the congestion control strategy being exercised for the particular application being served. The L-band transmit antenna is preferably physically integrated with the DTH/DBS receive antenna, but may also be an independent stand-alone antenna, depending on the proximity of the DTH/DBS and mobile satellites in use. Figure 4 shows the set-top controller in more detail. This consists of a program data store 100, a select program guide unit 101 (with IR remote control), a display program guide GUI (Graphical User Interface) 102, A unit 103 for permitting interaction between the GUI and the IR remote unit, and a unit 104 for displaying the selected channel on the TV screen. These components are found in a conventional set-top unit. In addition, the modified controller employed in the invention includes an interactive data store 110, a unit 1 1 for permitting the user to select the interactive mode with the IR remote control, a unit 112 for displaying a GUI for the selected application, a unit 113 for permitting interaction between the GUI 112 and the IR remote 61, and a message formatter 144. This formats messages on the send command from the IR remote unit 61, which are then forwarded to the L-band transmitter by the unit 1 15. A typical example of the invention might be a home shopping service, which would be used by an enrolled and registered user who has already supplied mailing and courier delivery addresses, credit card numbers, etc. to the home shopping network. To make use of the interactive return capability, the home shopping broadcast signal will include an order screen that is displayed to the user's TV on command from the remote control. Continuing to use the remote control, the user can navigate through the order screen, filling in ordering information pertinent to the item to be purchases. Such as quantity, color, size, etc. When complete, the user can send information to the home shopping service office as a "purchasing information request' using a "send message" button on the remote control. The home shopping service will immediately send an addressed message back to the user containing price, availability, delivery information, etc. as well as "yes, I wish to purchase", "payment method", "order change", or "cancellation", etc. selection boxes on the screen. After selection of the appropriate boxes, the user can again use the "send message" button on the remote control. The home shopping service would then send a confirmation message to the user. The user terminal addressing capability is already part of the DTH/DBS systems in place. The capability to decode and display screens related to interactive applications requires modification of the set top controller software in the set top unit 50. A modified wireless remote control 61 is also required with additional function buttons related to the interactive mode, such as "display interactive screen" and "send message". Remote control functions such as menu scrolling and menu item selection are normally available on typical wireless remote controllers supplied with DBS set top boxes, but the set-top controller 63 also requires modification to deal with the interactive-related TV display screens, message formatting, and send command functions. Formatted messages pertinent to the specific application are then processed by the L-band transmitter 70 and sent via the L-band satellite to the home shopping service office (in this case). Set top controller software additions and remote control unit modifications to standard units used with available DTH/DBS services accommodate a wide variety of applications of interest to users. The present invention provides an optimal solution to the problem of providing a retum path in typical consumer applications, where the amount of data transmitted on the retum path is small relative to the amount of data to be received on the forward path.

Claims: Claims 1. An interactive direct broadcast station comprising means for transmitting broadcast signals via satellite to an end user over a wideband satellite link, means for receiving retum signals from end users over a separate narrow band satellite retum link providing a retum path, and means for interpreting said retum signals to respond to requests from the end user. 2. An interactive direct broadcast station as claimed in claim 1 , further comprising a CDMA demodulator for demodulating CDMA modulated signals received on the retum link. 3. An interactive direct broadcast station as claimed in claim 1 or 2, further comprising a source of broadcast material, and an interface unit receiving said retum signals and operative to control said source in response thereto to select broadcast material to be transmitted to the end user. 4. An interactive direct broadcast station as claimed in any one of claims 1 to 3, wherein said interface unit includes ports for establishing communication with different service providers providing signals for broadcast over the wideband link. 5. An interactive direct broadcast station as claimed in any one of claims 1 to 4, wherein said wideband link is Ku band and said narrowband link is L-band. 6. A direct-to-home broadcast receiving system, comprising a receiver for receiving wideband broadcast signals from a hub station via satellite on a wideband satellite link, means for generating retum signals for transmission to said hub station, and a transmitter for transmitting said retum signals via satellite back to hub base station over a second narrowband link separate from said first link. 7. A direct-to-home broadcast receiving system as claimed in claim 6, further comprising a CDMA modulator for CDMA modulating said retum signals prior to transmission on the return link. 8. A direct-to-home broadcast receiving system as claimed in claim 6 or 7, further comprising a naπow beam antenna for receiving said broadcast signals and a wide beam antenna for transmitting said naπowband signals, said wide beam and narrow beam antenna being mounted in close proximity. 9. A direct-to-home broadcast receiving system as claimed in claim 8, further wherein said antenna are mounted on a common dish. 10. A direct-to-home broadcast receiving system as claimed in any of claims 6 to 9, wherein said transmitter is connected to said a controller receiving commands from a user for transmission back to the base station. 11. A direct-to-home broadcast receiving system as claimed in claim 10, wherein said controller is connected the transmitter by a CDMA modulator, which CDMA modulates the retum signals for transmission over the narrow band link. 12. A method of providing an interactive broadcast service comprising the steps of transmitting broadcast signals via a wideband satellite link to end users, receiving retum signals from said users transmitted over a narrowband satellite link separate from said first link, and responding to said retum signals to provide services requested by said users of the service. 13. A method as claimed in claim 12 wherein said retum signals are CDMA modulated. 14. A method as claimed in claim 12 wherein said broadcast signals are transmitted in the Ku band and the retum signals are transmitted in the L band. 15. A method as claimed in any one of claims 12 to 14 wherein said retum signals are operative to select specific broadcast material desired by an end user. 16. A method as claimed in any one of claims 12 to 14 wherein said retum signals are operative control the downloading of multimedia information from the Intemet or other sources to an end user. 17. An interactive direct broadcast satellite system comprising means for receiving a first Ku-band signal from a Ku broadcast satellite; means for decoding said Ku-band signal received from said Ku broadcast satellite; means for providing an encoded retum signal; CDMA modulation means for modulating said encoded retum signal to provide an encoded CDMA modulated signal, and means for transmitting said modulated encoded retum signal to an L-band satellite. 18. A direct broadcast satellite system as defined in claim 17, wherein the Ku broadcast satellite and the L-band satellite hubs are interconnected. 19. A direct broadcast sarellite system as defined in claim 17 further comprising a set top unit for receiving the decoded Ku-band signal received from said Ku broadcast sarellite, and for providing a retum signal to be encoded by said means for providing an encoded return signal. 20. A direct broadcast satellite system as defined in claim 19, wherein said means for receiving a first Ku-band signal, and said means for transmitting the modulated encoded retum signal comprise a single transmitting and receiving antenna. 21. A direct broadcast satellite system as defined in claim 19, wherein said means for transmitting the modulated encoded retum signal is mounted and combined with an existing Ku-band receiving antenna. 22. A modulating and demodulating transmitting and receiving unit for connection between a set top unit and an antenna, comprising: means to receive and encode information from the set top unit destined for said antenna means; and means to receive and decode information from said antenna means destined for said set top unit.

Inventors: HAUGLI HANS-CHRISTIAN, ZULIANI MICHAEL, HAUGLI, HANS-CHRISTIAN, ZULIANI, MICHAEL
Applicants: HAUGLI HANS CHRISTIAN, VISTAR TELECOMMUNICATIONS INC, ZULIANI MICHAEL, HAUGLI, HANS-CHRISTIAN, VISTAR TELECOMMUNICATIONS INC., ZULIANI, MICHAEL
Application year: 1997
Main classification: H04N7
IPC codes: H04N5, H04N7