MXPA99004428A - Real-time information delivery system for aircraft - Google Patents

Abstract

A satellite-based digital broadcast system is used to provide real-time news, entertainment and informational programs to aircraft passengers in flight. Transmissions from the satellite occur on a time division multiplex (TDM) downlink with different broadcast programs being transmitted on different TDM channels. A broadcast receiver is carried on board the aircraft, and includes a demultiplexer (60) for demultiplexing the TDM channels to reproduce the original broadcast programs. The broadcast receiver may be adapted to receive and reproduce both audio (64) and video (76) broadcast, as well as to provide other types of information delivery services. Encryption (72) of the broadcast programs may be used to restrict their use to a specific aircraft or airline company.

Description

SYSTEMS REAL-TIME INFORMATION SUPPLIER FOR AN AERIAL SHIP References to related applications: This material and related material is treated and claimed in the pending US Patent Application serial number 08 / 569,346, filed by S. Joseph Campanella on December 8, 1995; in an American patent application currently pending from Robert L. Johnstone et al., filed November 5, 1996, entitled "System for Providing Specific Data from a Location to a User" (Attorney Case 33876); in an American patent application currently pending from S. Joseph Campanella, deposited on November 5, 1996 and entitled "A Direct Broadcast Recipient that Provides Frame Synchronization and a Correlation for Multiplexed Transmissions with Time Division" (Case of Lawyer 33877A); in an American patent application currently pending in the name of S. Joseph Campanella, filed on November 5, 1996, entitled "Direct Broadcasting Receiver for Broadcasting in TDM" (Case of Lawyer 33877B); in an American patent application currently pending from S. Joseph Campanella, filed on November 5, 1996, which is titled "System for Formatting Dissemination Data for Satellite Transmission and Radio Reception" (Case of Lawyer 33877C); in an American patent application currently pending from S. Joseph Campanella et al., filed November 5, 1996 entitled "System for Managing the Use of Space Segments between Broadcasting Service Providers" (Attorney's Case 33877D ); in an American patent application currently pending from S. Joseph Campanella, filed on November 5, 1996 and entitled "Satellite Payload Processing System for Switching Upward Signals to Downlink Signals Multiplexed with Division" of Time "(Case of Lawyer 33877E); in a pending US patent application filed by S. Joseph Campanella, filed on November 5, 1996, entitled "Satellite Payload Processing System with Use of Multiple Phase Demultiplexing and Demodulation with Key in Displacement of Phase by Quadrature "(Case of Lawyer 33877F) as well as in a pending US patent application filed by S. Joseph Campanella, filed on November 5, 1996 and titled" Satellite Payload Processing System that Provides an Alignment of the On-board Rate "(Attorney's Case 33877G); All of these requests mentioned in an express form within this text are incorporated as reference material. FIELD OF THE INVENTION The present invention relates in general terms to the transmission and reception of information and is particularly concerned with a system that serves to provide real-time transmissions, audio, video and data, to passengers using a air Line. BACKGROUND OF THE INVENTION Modern airliners provide their passengers with a variety of entertainment programs, including films, scientific aspects, advertising, news, music and other types of video and audio programs. However, all these programs are pre-recorded (usually on a magnetic tape), sometimes days or even months before the flight starts. As a result, while on the one hand contemporary passengers using modern airlines are increasingly able to take advantage of certain high-tech services, such as telephone calls during the flight, they are cut off from news in live, sporting events and other events that occur during the course of a flight. So it is quite common for passengers on an airplane to run to the nearest television set immediately after their flights have landed at an airport, especially when some very important news occurs or when a sporting event is taking place. In some cases not even that option is available because the event is happening in a distant place and is not of local interest in the destination of such passenger. Although an airship is capable of receiving radio and television broadcast transmissions from terrestrial sources, this is not a practical way to provide news and entertainment programs, in real time, to airline passengers. One problem is that the effective range of most commercial broadcasting and television stations is limited to a distance of the order of 100 km. For a turbine aircraft flying at a speed exceeding 750 km / hr, it is clear that such an airship will be within the range of a broadcast earth station only for a short time. This time interval will typically be shorter than the duration of most entertainment or news programs. Another problem in the reception of terrestrial transmissions is that the relative distance between the airplane and the diffusion station changes rapidly when the airship flies by its flight orbit, and the result is great variations in signal strength and quality. of the transmission. In addition, for terrestrial transmissions that are capable of being received over long distances, the blocking effect of the earth's horizon can interfere with a correct reception of the signal. In the currently pending US patent application, assigned to common names, serial number 08 / 569,346, filed by S. Joseph Campanella on December 8, 1995 and in the other pending pending applications identified above, a new dissemination system is described global digital The system employs 3 geostationary satellites which each have 3 beams of contiguous sites in downlink that cover large masses of land. The reception mode that is attempted as the most important mode consists of a portable radio-receiver that has the ability to select one of several hundred first-order channels of 16 kilobits per second (kbps). These channels can be used individually for audio or text broadcasts or can also be combined to form digital streams as wide as 1.5 to 2.0 megabits per second (mbps). According to the selected mode, the uplink signals for these broadcasts can come either from a central point located at a discrete site or individually within the uplink coverage area of a satellite or from a plurality of terminals with very small individual aperture (VSAT) distributed across the entire uplink coverage area of the satellite. The basis of the present invention is the recognition that a satellite-based digital broadcasting system of this type can be used to provide real-time broadcast programs to airplanes in flight, without suffering from the disadvantages and inherent limitations of the prior art. SUMMARY OF THE INVENTION In view of the foregoing, it is an object of the present invention to provide a system for delivering broadcast programs in real time to passengers in an aircraft, which do not suffer from significant limitations in ranges, variations in signal strength or problems of blocking by horizons. Another object of the present invention is to provide broadcast programs to an aircraft in multiple channels so that airline passengers can select from a large number of different programs. A further object of the present invention is to provide broadcast programs both in audio, in video to passengers of an airline, as well as other types of services providing information.

Still another object of the present invention is to create the possibility of restricting certain broadcast programs so that they can only be received by certain airplanes or groups of airplanes so that the broadcast programs adjusted to certain air carriers can be reserved for use. for such companies. These and other objects of the present invention are achieved by the use of a digital broadcasting system, based on satellite, to provide real-time broadcast programs to airborne aircraft in flight. Due to the wide geographic coverage area that can be obtained with a satellite, the aircraft will remain within the range of the satellite for a period long enough to allow most types of live broadcast programs to be received from a satellite. interrupted way. In addition, due to the large distance between the satellite and the airship (particularly in the case of a geostationary satellite), problems arising from variations in the strength of a signal or blockage due to the presence of the signal are reduced to a minimum. horizon. Accordingly, in one aspect the present invention is directed to a system for providing real time broadcast programs to passengers present in an airship. The system comprises at least one terrestrial broadcast station for transmitting a plurality of different broadcast programs and a satellite relay for receiving and retransmitting broadcast programs. The retransmission of the surveyed satellite occurs in downlink in a multiplex system with time division (international abbreviation: TDM) with different broadcast programs being transmitted by different TDM channels in the downlink. On board the aircraft is a broadcast receiver that includes a demultiplexer to demultiplex the TDM channels in order to reproduce the original broadcast programs. Preferably, this broadcast receiver is adapted to receive and reproduce both audio and video programs and also to provide other types of information delivery services. In a preferred embodiment of the invention at least one of the TDM channels contains an encrypted broadcast program and the broadcast receiver is adapted to describe the encrypted broadcast program so that the program can be restricted to an airship or airline, specific. In another aspect, the present invention is directed to an on-board broadcast receiver to provide a plurality of real-time broadcast programs to passengers on board an aircraft. The broadcast programs are transmitted to the receiver by a satellite on a time division multiplexed downlink (TDM), and different broadcast programs are transmitted on different TDM channels on the downlink. The broadcast receiver comprises a satellite antenna that is on board the aircraft to receive the TDM downlink, a demodulator coupled to the antenna to demodulate the TDM double link and a demultiplexer coupled to the demodulator to demultiplex the TDM downlink for reproduce the original broadcast programs. In still another aspect, the present invention is directed to a method for providing real-time broadcast programs to passengers of an airship. The method comprises the steps of transmitting a plurality of different broadcast programs from at least one terrestrial broadcast station to a relay satellite; retransmit the broadcast programs from the relay satellite to an airborne spacecraft in which the retransmission occurs in a downlink signal with a multiplexer for time division (TDM), in whose system different broadcast programs are transmitted by different TDM channels in the downlink signal; and receiving and demultiplexing the downlink signal on board the aircraft to reproduce the original broadcast programs. BRIEF DESCRIPTION OF THE DRAWINGS The different objects, advantages and novel features of the present invention will be presented more clearly if one takes note of the following detailed description which serves to study together with the attached drawings, in which: Figure 1 is an illustration of a digital broadcasting system based on in satellite that uses 3 geostationary satellites that cover the main land masses outside the United States and Europe. Figure 2 is a diagram illustrating the manner in which a satellite-based digital broadcast system of the type illustrated in Figure 1 can be used to provide audio programs, information delivery services and other broadband broadcast transmissions relatively low directly to an airship in flight over Earth. Figure 3 is a diagram illustrating the manner in which a satellite-based digital diffuser system of the type illustrated in Figure 1 can be used to provide video programs and other broadcast broadband relatively high transmission directly to an airship. in flight above the Earth. Figure 4 illustrates the details of an on-board broadcast receiver and other equipment that can be installed in an airship to provide real-time broadcast programming in accordance with the principles of the present invention. In all the drawings it will be understood that the same reference numbers refer to similar parts and components. DESCRIPTION OF THE PREFERRED EMBODIMENT A system for providing real-time broadcast programs to an aircraft in accordance with the present invention is preferably implemented in connection with a digital broadcast system based on a satellite of the type described in FIG. US Patent Application currently pending, mentioned above, serial number 08 / 569,346, filed December 8, 1995, as well as in the other pending pending applications identified above. As shown in Figure 1, the digital broadcast system consists preferably of 3 geostationary satellites 10, 12 and 14 located above the main landmasses of planet Earth outside the United States and Europe. Thus, satellite 10 provides service to Latin America and South America, satellite 12 provides service to Africa and the Middle East, and satellite 14 provides service to the southern and eastern regions of Asia. The coverage area of the downlink system of each satellite 10, 12 and 14 is defined by three contiguous site beams 16. The coverage area of the uplink 18 of each satellite 10, 12 and 14 is substantially larger and defines the area in which diffusion stations can be placed, based on earth. As will be clear from Figure 1, the coverage allowed by the 3 contiguous downlink site beams 16 of each satellite 10, 12 and 14 is of a very large size and an aircraft will typically remain within the coverage area of the downlink of a satellite for several hours as it proceeds on its flight path. In a preferred embodiment of the system shown in Figure 1, downlink transmissions are presented in the frequency band of 1476 to 1492 megahertz (MHz), which has been assigned to digital audio broadcasting (DAB). of broadcast satellite service (BSS). International abbreviations mean Broadcast Satellite Service, Digital Audio Broadcast. This occurs within the L band of the radio frequencies (1100 to 2000 MHz). The uplink transmissions from the broadcast stations (not shown) to satellites 10, 12 and 14 use frequencies between 7050 and 7075 MHz, which corresponds to the X band. Each downlink site beam 16 from a satellite given 10, 12 or 14 covers approximately 14 million square kilometers within the contours of the energy distribution that remain at 4 decibels (dB) down from the center of the beam and 20 million square kilometers within the contours remaining 8 dB down from the center of the beam. The beam center margin is 14 dB based on a gain-to-temperature ratio at the receiver of -13 dB / K. Referring now to Figure 2, the uplink signals generated by a plurality of broadcast stations of the type VSAT, 2, are modulated up to 288 channels of type (FDMA) multiple access to frequency division, 22, of separate type and are transmitted to one of the satellites The satellite 10 is only shown by way of example, although it will be understood that similar signals will be transmitted to the satellites 12 and 14 by diffusion stations located in their respective coverage regions. Each broadcast station 20 preferably has the ability to establish an uplink directly from its own satellite facilities 10 and to place one or more increments of the primary rate of 16 kilobets per second (Kbps) on a single conveyor. The use of FDMA channels 22 for uplink transmissions allows a remarkable degree of flexibility between the multiple independent broadcast stations 20. The above-mentioned increases in the primary rate (international abbreviation PRI) are preferably the fundamental building block or be the rudimentary unit that is used in the system to set the size of the channels and they can be combined to achieve higher rates or bit rates. For example, 8 PRI increments can be combined to create program channels with bit rates of up to 128 kbps. The conversion between the uplink FDMA channels 22 and the multi-channel downlink channels per carrier and with the time division multiplexer (MCPC / TDM), 24, is achieved on board the satellite 10 at the level of the band. base. Each primary rate channel transmitted by a broadcast station 20 is demultiplexed into individual 16 kb baseband signals. The different channels are then routed to one or more of the downlink beams 16, of which each operates on a single conveyor frequency. This baseband processing provides a high level of channel control in terms of uplink frequency allocation and channel routing between uplink and downlink signals. Further details regarding the operation of satellite 10 and diffusion stations 20 can be found in the currently pending patent application, mentioned above, serial number 08 / 569,346. The satellite 10 contains 2 communication payloads. In the first payload, which is referred to by the payload term "processing", a polyphase demultiplexer and a demodulator receives the different signals of the uplink FDMA 22, generates a composite signal in which it is multiplexed in time The information is the data of the 288 FDMA signals and executes the demodulation at high speed of the serial data. A routing switch selectively routes the different channels of the serial data to the whole, some or none of the downlink site beams 16 and then modulates and downconverts the 3 downlink signals. Tube amplifiers with traveling waves amplify the 3 downlink signals, which are radiated to Earth by L-band transmission antennas. The second type of communication payload transported by satellite 10 (which is not used in the Figure 2 but discussed below in relation to Figure 3) is a "transparent" payload that converts digital uplink transporters from the frequency locations within the X-band uplink spectrum to frequency locations within the downlink spectrum of the L-band. The digital transport stream for the transparent payload is generated and modulated with the video programming in a broadcast station and transmitted to satellite 10, it is received and converted into frequency at a frequency downlink, then amplified by an amplifier of tube with traveling waves and is transmitted in one of the bundles of the downlink 16. Different downlink conveyor frequencies are used for the transparent and processing payloads of satellite 10. Figure 2 illustrates the way in which broadcasts in audio and other services providing information with a relatively low bandwidth can be supplied to an airship 25 using the processing payload of satellite 10. Aircraft 25 is in flight above Earth in a place within the coverage area defined by the 3 site beams of the contiguous downlink 16 transmitted by the satellite 10. The broadcast programs serving to be received by the ship 25 are transmitted to the satellite 10 by one or more of the stations of diffusion 20 using the uplinks of FDMA 22. The processing payload on board satellite 10 routes the channels of primary rate of 16 kbps to l or several of the downlink beams 16 as determined by control equipment that is grounded (not shown). Programming sources for broadcasting stations 20 include international radio broadcast services 26 (such as VOA or BBC), digital audio broadcasting (DAB) services 28, information dissemination services 30 (such as the PointCast news service available on the Internet, satellite paging services 32, music and news programs 34 and other services 36 (such as stock quotes, weather forecasts, emergency announcements and the like.) The satellite paging service 32 can be supplied by paging the airship 25 in its entirety and then transmitting the alpha numeric information indicating the name of the passenger with a brief message for the latter It will be understood that each of the broadcast sources 26-36 may be associated with a separate instance of the broadcast stations 20 or several of the sources 26 through 36 may be transmitted from a single broadcast station 20. Each broadcast station can transmit up to 32 channels of primary rate of 16 kbps each, and the overall capacity in uplink of the system is equivalent to 288 channels in uplink dente, of primordial rate. There are ninety-six (96) primary rate channels that are selected and multiplexed by satellite 10 for transmission in each downlink beam 16. The number of channels transmitted by each broadcast station 20 will depend on the type of broadcast source ( or broadcast sources) involved, and a single 16 kbps channel is sufficient to achieve monophonic voice programs, data services and the like. The monophonic music with FM quality or frequency modulated, can be transmitted with the use of two channels of primary rate of 16 kbps, and stereophonic music with FM quality can be used with the use of 4 channels of primary rate of 16 kbps while stereo music with CD quality (compact disc) can be transmitted with the use of 8 channels of primary rate of 16 kbps. All these rates in quoted bits are for encoded type audio sources with the use of an MPEG2 system encoding, layer 3. In the arrangement shown in Figure 2, the programmatic content of some of the downlink channels can be common both for the passengers of the airship as for the eavesdropping. This gives passengers on the airship the option of listening in real time to the same radio programs, sporting events and other broadcast programs they receive at home. Other channels can be packaged especially for use on an airline by including advertising or certain program content that is specifically geared toward airline passengers. These channels can be encrypted by sources 26-36 and then can be described on the receiving equipment that is carried aboard the aircraft 25. The encryption can be specific for a specific airline or for programs that could be interesting for air passengers In general, it can be shared by a number of different airlines. Figure 3 illustrates how the transparent payload of satellite 10 can be used to provide video broadcast programs and other high bandwidth information provider services for airship 25. In this case, the sources of Broadcast will typically consist of real-time video feeds from live sporting events, live news events or live features. In the example shown, the broadcast sources include live video feeds from a football game for the 38 world championship, an Olympic event 40, an American football game in the Super Bowl 42, a baseball game of the series world 44 as well as a 46 rock concert. The source of broadcast can also consist of a live video feed from a major news event (such as some inauguration, the funeral of a head of state, a marriage of the Royalty or something similar) as represented by block 48. In all these cases the transmissions in uplink 49 not only come from small broadcast stations of the VSAT 20 type as is the case of Figure 2 but instead can come from stations in Greater points 50 that are capable of transmitting with larger bandwidths. With compression techniques currently available, a bandwidth of 1.5 to 2.0 mbps is sufficient to transmit a video in full motion and of acceptable quality. To achieve the desired bandwidth, the bandwidth for multiple TDM downlink channels in the broadcast station is combined. For example, when the bandwidth of 96 TDM channels is combined, the aggregate bitrate will be 1536 mbps. Figure 4 illustrates the equipment that is taken on board the airship 24 to receive and reproduce broadcast programs picked up through one of the satellites 10, 12 or 14 of Figure 1. The beam 16 of the TDM downlink is received by an antenna 52 which is mounted on the upper outer face of the fuselage of the aircraft. This antenna 52 is connected to a front end of RF (radio frequencies) 54 that can be manually or automatically switched (via an input 53) within the carrier frequencies associated with the 3 separate downlink beams 16 transmitted by each satellite. The RF front end 54 receives all 96 TDM channels associated with the satellite processing payload as well as all 96 digital carriers associated with the satellite payload transparent (which are modulated in a different one). conveyor frequency). The processed channels are routed to a demodulation and synchronization unit 56 whose output is a baseband signal of 1536 mbps. The transparent channels are routed to a similar demodulation and synchronization unit 58 whose output also consists of a baseband signal of 1536 mb s. The baseband signal from the unit 56 is applied to the input of a demultiplexer 60 which produces 96 output channels 61 of 16 kbps. These channels are subjected to a decoding, FEC, audio decoding and block description 62. Channels 61 alone or in combination can be used to reproduce audio broadcasts of different quality levels or to provide information delivery services. Channels that carry audio information are subjected to a digital-to-analog conversion (not shown) that produce audible signals that can be made available to passengers on the plane through headphones or speakers. Typically, a large commercial air ship already has an audio distribution system 64 that has output 65 in the different passenger seats and the decoded audio channels can be coupled to this system at entrances 66. The sound distribution 64 can also receive the inputs 68 of the audio tape systems or other audio, auxiliary sources. The output of the demodulation and synchronization unit 58 for the transparent downlink channels is applied to the input of a decoding and decoding unit of FEC 72. The output of the unit 72 is a digital video signal that is subjected to a conversion from digital-to-analog (not shown) and applied to the input 73 of a video distribution system 74 carried by the aircraft. The video distribution system also receives 75 inputs from auxiliary video sources such as video cassette players. The outputs 76 of the video distribution system 74 may be connected to shared video monitors or protection screens that are mounted from the ceiling of the aircraft cabin or to individual LCD-type video screens that are provided on each seat of the passenger The audio portion of a video program that is received by the video distribution system 74 is connected to the sound distribution system 64 through line 78. In order to allow the information providing services to be transported through of the processed channels of the TDM downlink to be visualized by the video distribution system 74 of the airship, these channels are coupled to the video distribution system 74 through the lines 80. In this way they can be displayed visually to the passengers of the airline for example the quotes of the stock market, reports or news information and other types of data. In view of the fact that the aerial of the airship 54 operates in the L-band, it can be shared with other receiving equipment or transmitter on board the ship, which operates in this band. For example, the telephone services of the airship operating through the satellite INMARSAT use frequencies in the L-band. As noted in Figure 1, the size of each site beam 16 is such that an airship that crosses its diameter It will take several hours to pass through the beam, thus ensuring the continuity of the largest broadcast events for airline passengers. It is equally possible to transmit the same broadcast program in two (or 34) to the totality of the 3 beams) of the site beams 16 associated with a given satellite to ensure continuity even longer flights. Although the site beams 16 transmitted by a given satellite have different carrier frequencies, the carrier frequency in the front end unit RF 54 of Figure 4 can be changed either manually (or automatically) through the input 53 when it is moved the air ship 25 of a beam of site 16 to the next. For live music, talk and news channels it is anticipated that a group of airlines in each region will be able to agree on a set of channels that can be "provided through the respective satellite, 10, 12 or 14 Certain channels can be reserved for unique programs for each participating airline.

. The channels with live information, the real-time nature of the information provider system allow it to be updated, the content of the information (news, stock quotes and the like) as desired. frequency. This can not be done on a common basis for channels that are "shared by different airlines or individually for channels that are reserved to certain airlines." Similarly, advertisements can be selected by the participating airlines and placed on common channels. or reserved Although airlines may wish to offer most of the broadcast programs at no cost to their passengers, it is possible to provide certain broadcast programs selected for a fee to be charged to a credit or debit card. present invention has been described with reference to a preferred embodiment thereof it will be understood that the invention is not limited to these details.Substitutions and modifications have been suggested in the above description and others will be suggested to those skilled in the art. All these substitutions and modifications should be covered by the scope of the invention as defined in the appended claims.

Claims (20)

1. CLAIMS 1. A system for providing real-time broadcast programs to passengers present in an airship, comprising: at least one terrestrial broadcast station to transmit a plurality of different broadcast programs in a low bandwidth and therefore minus a broadcast program in a high bandwidth; at least one satellite relay to receive and transmit low bandwidth broadcast programs and that high bandwidth broadcast program, such retransmission occurring at least one downlink signal in which different copies of the broadcast programs in low bandwidth they are transmitted in different multiplexed channels with time division (international abbreviation: TDM) with the same conveyor frequency of less than approximately 3000 MHz; and a broadcast receiver that is on board an aircraft, receiver including at least one demodulator to demodulate at least said downlink signal and a demultiplexer coupled to the demodulator to demultiplex the TDM channels in order to reproduce the plurality of broadcast programs in a low bandwidth, the broadcast receiver being coupled to an entertainment system for passengers on board the ship to provide such low bandwidth broadcast programs and at least that broadcast program in High bandwidth to passengers who are on board the airship.
2. 2. A system as defined in claim 1 wherein at least one downlink signal contains an encrypted broadcast program and wherein the broadcast receiver is adapted to describe the encrypted broadcast program.
3. 3. A system as defined in claim 1 wherein at least one downlink signal comprises a site beam that includes at least a portion of the flight path of the aircraft.
4. 4. A system as defined in the claim 1 in which the retransmission from the relay satellite occurs in a site beam that includes at least a portion of the flight path of said airship.
5. A system as defined in claim 1 in which the retransmission from the relay satellite occurs in a plurality of contiguous site beams that collectively include at least a portion of the flight path of the aircraft and in that at less one of the broadcast programs is broadcast in more than one of the site beams.
6. 6. A system as defined in claim 5 wherein the plurality of contiguous site beams have different carrier frequencies and in which the broadcast receiver can be interchanged between said carrier frequencies.
7. A system as defined in claim 5 in which the retransmission of the relay satellite occurs in the frequency band 1100 MHz to 2000 MHz.
8. 8. A system as defined in the claim 1 in which the broadcasting receiver is coupled to an on-board passenger entertainment system to deliver broadcast programs to a plurality of passengers.
9. 9. An on-board broadcast receiver to provide a plurality of real-time broadcast programs to passengers of an airship, these broadcast programs being transmitted from a satellite on a time division multiplex downlink (TDM) being transmitted in different instances of such broadcast programs in different TDM channels in the downlink, the broadcast receiver comprising: a satellite antenna held by the airship to receive the downlink of TDM; a demodulator coupled to the ante to demodulate the TDM downlink; and a demultiplexer coupled to the demodulator to demultiplex the TDM downlink in order to reproduce the plurality of broadcast programs.
10. 10. A broadcast receiver on board as defined in claim 9 in which the broadcast receiver is adapted to receive and play broadcast programs in both audio and video.
11. An on-board broadcast receiver as defined in claim 9 wherein at least one instance of said TDM channels contains an encrypted broadcast program and wherein the broadcast receiver is adapted to describe the encrypted broadcast program .
12. 12. An on-board broadcast receiver as defined in claim 9 wherein the diffusion receiver can be interchangeable between at least two different carrier frequencies.
13. An on-board broadcast receiver as defined in claim 9 in which the broadcast receiver is adapted to receive the downlink transmissions at a carrier frequency in the range of 1100 MHz to 2000 MHz.
14. 14. A broadcast receiver on board as defined in claim 9 in which the broadcast receiver is coupled to an entertainment system for passengers on board to provide broadcast programs to a plurality of passengers.
15. 15. A method to provide real-time broadcast programs to passengers in an airship, which comprises: transmitting a plurality of different broadcast programs from at least one terrestrial broadcast station to a relay satellite; retransmitting the broadcast programs from the relay satellite to an airship in flight, this retransmission occurring in a downlink signal in a multiplex system with time division (TDM), different copies of the broadcast programs being transmitted in different channels of TDM in said downlink signals; and receiving and demultiplexing the downlink signal on board the aircraft to reproduce the plurality of broadcast programs.
16. 16. A method as defined in the claim 15 in which at least one instance of said TDM channels contains an encrypted broadcast program and in which the method also comprises the step of describing the encrypted broadcast program.
17. 17. A method as defined in claim 15 in which the retransmission from the relay satellite occurs in a site beam that includes at least a portion of the flight path of such an airship.
18. 18. A method as defined in the claim 15 in which the retransmission from the relay satellite occurs in a plurality of contiguous site beams that collectively include at least a portion of the flight path of the aircraft and that further comprises the step of transmitting at least one instance of the broadcast programs in more than one copy of the site beams.
19. A method as defined in claim 15 in which the relay of the relay satellite occurs in a plurality of contiguous site beams having different carrier frequencies, including such site beams contiguously contiguous to at least a portion of the flight path of the airship and in which the step of receiving and demultiplexing the downlink signal on board the air ship comprises receiving and demultiplexing different specimens of the carrier frequencies at different times.
20. 20. A method as defined in claim 15 wherein the retransmission from the satellite relay occurs in the frequency band 1100 MHz to 2000 MHz.