Telecommunications – Transmitter and receiver at separate stations – Plural transmitters or receivers
Reexamination Certificate
1999-11-05
2002-05-28
Trost, William (Department: 2683)
Telecommunications
Transmitter and receiver at separate stations
Plural transmitters or receivers
C455S426100, C455S419000, C455S045000, C455S185100, C455S186100, C455S404200
Reexamination Certificate
active
06397076
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to dispatch radio communications. More specifically, the present invention relates to dispatch communications in broadcast radio receivers adapted to receive dispatch messages during the reception of conventional program signals in a broadcast radio system.
While the present invention is described herein with reference to illustrative embodiments for particular applications, it should be understood that the invention is not limited thereto. Those having ordinary skill in the art and access to the teachings provided herein will recognize additional modifications, applications, and embodiments within the scope thereof and additional fields in which the present invention would be of significant utility.
2. Description of the Related Art
Satellite radio operators will soon provide digital quality radio broadcast services covering the entire continental United States. These services intend to offer approximately 100 channels, of which nearly 50 channels will provide music with the remaining stations offering news, sports, talk and data channels. According to C. E. Unterberg, Towbin, satellite radio has the capability to revolutionize the radio industry, in the same manner that cable and satellite television revolutionized the television industry.
Satellite radio has the ability to improve terrestrial radio's potential by offering a better audio quality, greater coverage and fewer commercials. Accordingly, in October of 1997, the Federal Communications Commission (FCC) granted two national satellite radio broadcast licenses. The FCC allocated 25 megahertz (MHz) of the electromagnetic spectrum for satellite digital broadcasting, 12.5 MHz of which are owned by CD Radio and 12.5 MHz of which are owned by the assignee of the present application “XM Satellite Radio Inc.” The system plan for each licensee presently includes transmission of substantially the same program content from two or more geosynchronous satellites to both mobile and fixed receivers on the ground. In urban canyons and other high population density areas with limited line-of-sight satellite coverage, terrestrial repeaters will simultaneously broadcast the same program content in order to improve coverage reliability.
In accordance with the XM frequency plan, each of two geosynchronous Hughes 702 satellites will transmit identical or at least similar program content. The signals will be transmitted with QPSK digital modulation. The assigned 12.5 MHz bandwidth is called the “XM” band. The modulation scheme allows up to 4096 Mbits/s of total user data to be distributed across the available bandwidth. The data transmission will be multiplexed according to a TDM interleaving scheme, multiplexing that various channels of program content together, which provides for the simultaneous transmission and simultaneous reception of the various channels. Receivers will receive and de-interleave, or demultiplex, the channels for reception of the desired program content by end users.
The new XM band broadcast system will deliver a large volume of digital quality audio, including music and other program content to end users. While broadcasts which closely mimic convention commercial analog broadcast will be provided, the inherent capability to simultaneously broadcast and simultaneously receive the various channels makes it possible to provide advanced program content and messaging capabilities will be possible. It is anticipated that end users may desire special services that meet their particular needs. For example, in a fleet environment, where multiple end users are related in a personal or business nature, specialty messaging, otherwise known as dispatch messages, may be desired so that a particular fleet of users can be advised with information conforming to their needs. In a similar vein, individual users may desire to receive specialty, or dispatch messages, directed to them personally. However, since users in a fleet environment, or individual users, may be monitoring conventional broadcast program content, they may not be ‘tuned’ to an alternate channel comprising the specialty information.
Thus there is a need in the art for a method and device to deliver dispatch messages which are transmitted, received, and recognized notwithstanding the fact that the users are monitoring program content broadcast to a general audience.
SUMMARY OF THE INVENTION
The need in the art is addressed by the apparatus and methods of the present invention. The inventive method operates in a satellite digital radio broadcast system in which dispatch radio signals are provided to a receiver in the system which transmits dispatch alert messages on broadcast information channels, transmits dispatch messages on dispatch broadcast channels, and transmits program content on broadcast channels. The receiver simultaneously monitors a broadcast information channel TDM slot to receive dispatch alert messages while receiving program content on a broadcast channel TDM slot. When a dispatch alert message is sent, and upon receiving the dispatch alert message on the broadcast information channel, which identifies a dispatch broadcast channel and a dispatch message ID code, the radio compares the dispatch message ID code to another previously stored dispatch ID code in the receiver. If the two are found to be equal, the receiver recognizes the message as being addressed to that particular receiver and demultiplexes a dispatch message identified by the dispatch ID code on the dispatch broadcast channel. The receiver then provides the dispatch message to an audio output circuit, if it is an audio message, and upon completion of the dispatch message, subsequently reverts to receiving the broadcast channel. On the other hand, if the dispatch message is a data message, the receiver stores the message in a memory and utilizes it in another appropriate fashion, such as displaying it on a display or delivering it to another computing device or function. In this fashion, the user can monitor program content on a convention broadcast channel, yet still receive dispatch message as they occur, then revert to the previously selected program content.
In the illustrative embodiment, each radio in the system has a unique dispatch ID code previously stored within a memory which allows dispatch messages to be uniquely addressed to that particular radio. All radios compatible with the system also have a common dispatch ID code previously stored within the memory. In this way, dispatch messages may be sent to all radios simultaneously. This is useful for emergency situations and situations where the system operator, or others, desire to address a dispatch message to all users within a system.
In the situation where a fleet of receivers share a common interest, such as in a business environment, the system and receivers are adapted to be organized so that all members of the fleet receive the same dispatch message, but no other users in the system receive it. The system broadcasts ID code assignment messages on the broadcast information channels, and the ID code assignment messages include assigned dispatch ID codes related to unique dispatch ID codes of the receivers in the targeted fleet or other grouping of receivers. The receivers receive an ID code assignment message on the broadcast information channel. The ID code assignment message has within it an assigned dispatch ID code and a unique dispatch ID code. The receiver compares the unique dispatch ID code in the message to the unique previously stored dispatch ID code in the receiver. If they are found to be equal, the receiver stores the assigned dispatch ID code in its memory so that subsequently received dispatch message can be compared with the, now stored, assigned dispatch ID code. This allows the receiver to receive messages addressed to the assigned dispatch ID code as well as the unique dispatch ID code and the common dispatch ID code. In the case of a fleet, each of the receivers in the fleet are programmed with the same assigned d
Brown David L.
Wadin Craig
Benman, Esq. William J.
Le Danh
Trost William
XM Satellite Radio Inc.
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