Patent Application
20140099879
Satellite audio and video broadcasting systems for concurrent, near-simultaneous broadcast to mobile and fixed receivers of satellite broadcast audio information and of internet streaming of at least the same audio information, and of video and data information, too. The streamed internet information provides an ancillary terrestrial component that supplements the satellite broadcast information, and that provides a return channel from receivers in areas where wireless internet services are available.
Sirius XM Radio Inc. operates a Satellite Digital Audio Radio System (SDARS) to broadcast audio, video, and data content to mobile and fixed receivers in the United States and Canada. The Sirius XM broadcast network delivers signals to such receivers with audio broadcast information from two geographically-separated satellites and, in urban areas, an ancillary signal delivered by a terrestrial repeater. Service is available when any one of these three signals is available with sufficient field strength at the user's receiver. The hybrid satellite-terrestrial network improves service availability in urban environments, providing a signal in areas in which a mobile user's line of sight may be blocked to both satellites. The custom-designed Sirius XM receivers decode and combine two or more of the received signals to play the content to the user with no gaps in service. The satellite network provides no return channel from any satellite signal receiver.
Expansion of the terrestrial repeater network is constrained by several factors: regulatory requirements, cost, and technical limitations. Each repeater must be individually licensed by the appropriate regulatory agency, a process which imposes significant lead time and additional costs before the repeater can be constructed. The initial cost of the repeater equipment and then the recurring maintenance and lease costs add up quickly in a network of several hundred repeaters. Technical concerns such as interference from repeaters with overlapping coverage areas also limit the location of each repeater and the overall size of the network.
While the current mobile broadcast network architecture has proven to provide a highly robust service, the network is costly to maintain and provides limited ancillary signal coverage.
The systems and methods of this invention surmount these problems.
The systems and methods of this invention use a combination of satellite, terrestrial repeater, and internet delivered signals, all with at least some common content, to implement a broadcasting system to mobile and fixed receivers and to provide a return channel for users in some areas, e.g., urban and suburban areas.
The internet delivered signal may supplement or replace signals from terrestrial repeaters in some areas, e.g., well-connected urban and suburban areas, and may improve service coverage and service offerings. Service coverage increases significantly. The SDARS service area is extended to any location with an internet connection and to any type of internet-connected device. Home and office service becomes feasible without a dedicated receiver or a satellite antenna. Mobile users in many areas can access the broadcast information in their cars, and on mass transit systems, including subways and tunnels that have cellular or WiMax coverage.
Bandwidth can be used efficiently by segmenting channel assignments between satellite/internet as appropriate. Content that has a wide range of interest such as music and national news, talk, and sports may be delivered by satellite, repeater, and Internet in order to reach the widest possible audience. Content of a more local nature, such as weather and traffic conditions, may be offered via internet with better granularity for specific locations rather than broadcasting such information across the entire satellite coverage area. Local-only news and sports, such as high school results, may be offered only in a modest-sized region of interest via internet. Satellites need not broadcast content of local interest to all areas, thus using satellite bandwidth more efficiently. Better allocation of satellite bandwidth may permit greater programming variety, including more niche content, such as non-English language talk and music.
The addition of a return channel via internet within service areas also increases the variety of service offerings available. Search, point of sale, and personalized features all become feasible with an internet return channel available to users.
Receivers which transparently switch between satellite, repeater, and internet reception increase the scope of services available to mobile users, and lead to more efficient use of bandwidth for the overall service. Such receivers may provide quality of service comparable to that of the existing SDARS network despite the variations in satellite signal strength, repeater availability, wireless network connectivity, and Internet data rates that some receivers encounter.
The systems and methods of this invention can better be understood by reference to the drawings, in which:
The systems and methods of the invention improve upon the current satellite audio broadcast system for use with fixed and mobile receivers in the service area. The mobile receivers have antennas configured to view the sky where satellites would be visible and can also receive signals from terrestrial repeaters and connect to the internet to both receive and send signals.
Analysis input parameters for these systems and methods are: the definition of the geographical service area, and the quality and type(s) of service to be provided. The quality of service is defined as the percent of time service is unavailable due to satellite signal outage because of physical blockage, multipath or tree/foliage attenuation. When satellite signal outage arises from physical signal delivery blockage from buildings in urban environments, the current systems/methods deliver ancillary signals to maintain service availability.
Current implementations of the ancillary signal delivery operate over limited geographical coverage areas. The addition of internet-delivered ancillary signals expands the broadcast service areas to any area where any internet-capable device can connect to the internet. As a result, internet ancillary service improves service availability and expands service area.
Adding internet ancillary service to the fixed and mobile system receivers improves the type of services provided by enabling more efficient use of bandwidth and by providing two-way services. The amount and range of content broadcast via the satellite and repeater network can be expanded and bandwidth recouped by transferring local-interest content to internet delivery. An internet return channel enables users to ask for entertainment and data they want, delivering information to meet individual requests.
Studio 27 delivers substantially the same audio information, substantially concurrently, via path 30, internet connection 31, internet provider 34, path 32, tower 33, and path 34, to mobile receiver 17, and to all other receivers in the system that have internet accessibility. The receivers output one of these four signals, alone or supplemented by one or more of the other three signals, to assure uninterrupted service. The internet input also provides video and data information not available from the other three signal sources, and a return channel for a receiver to send a user message via the internet.
The mobile radio receiver also receives and transmits wireless terrestrial signals via an antenna 27 whose bandwidth and beamwidth is adequate to receive and transmit wireless radio frequency signals with cellular and WiFi repeaters. The received signal is amplified in a preamplifier 28 and, if the signal path is enabled by the user via the optional on/off switch 29, processed via a wireless modem 30. The receiver adjusts the timing of the signal by a time approximately equal to the desired amount of buffering to protect against loss of data packets in the wireless stream (Ti) via adjustable delay circuit 31. The internet signal is then divided (via divider 32) so that one path goes through the same comparator 26 to synchronize it with the satellite and terrestrial repeater signals while the other path goes to selector/combiner 33.
All of the received, synchronized signals are then sent to the selector/combiner circuit 33. The selector circuit chooses the program material from the received signals based on availability, and in a continuous sequence, based on the time code. The combiner continuously sums the received signals that are above a predetermined threshold level. The output from the selector/combiner is the continuous program material with substantially no discontinuities, even when the mobile radio receiver is unable to receive all transmissions, up to a time limit determined by the maximum amount of signal delay allowed.
The output of the selector/combiner circuit feeds the mobile radio receiver program presentation device 34, which may contain devices such as an audio detector, amplifier, a user interface, and loudspeakers and/or a visual display and/or a data terminal such as a computer. The program presentation device may also contain memory to store content for later use and/or a software processor to allow content to be formatted and presented in user-friendly applications. A presentation device may be battery operated and/or allow connections to external power sources. Alternately, the selector/combiner output could be fed to an external presentation device allowing the user to select the preferred device and to change to new presentation devices.
