Abstract:
A method and a device for receiving wireless broadcast signals are provided. The device includes a positioning module, a memory storing therein a first information table and a second information table, a signal-receiving and processing module, a processor and a client terminal. The method includes steps of: receiving a first wireless broadcast signal at a first frequency contained in the first information table and presenting contents represented by the first wireless broadcast signal when the device is positioned in a first broadcast area; automatically searching for a second frequency in the second information table when the device is positioned in a second broadcast area wherein the second frequency corresponds to the information associated with the first frequency in the first information table; and receiving a second wireless broadcast signal at the second frequency and presenting contents represented by the second wireless broadcast signal.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a method and a device for receiving wireless broadcast signals, and more particularly to a method and a device for receiving wireless broadcast signals during transportation between different broadcast areas. 
       BACKGROUND OF THE INVENTION 
       [0002]    Recent TV programs include cable TV programs and wireless TV programs. The wireless broadcasting is the over-the-air distribution of video signals which transmit programs to an audience by radio frequency signals. The wireless signals are received and then displayed by television or receiver for wireless broadcast signals or TV signals. Thus, the audience can watch TV programs represented by the wireless signals. 
         [0003]    The technology related to wireless TV programs has been highly developed and the wireless TV signals can transmit data for relatively wider area. In the effective broadcast area of a broadcast station, a simple antenna device or other receiver device for the wireless TV signals can receive and convert the wireless signals into video data to be displayed to the audience. If the receiver device is implemented by a mobile way, the user can receive TV signals and watch TV programs conveniently in mobile environments. 
         [0004]    With increasing development of mobile computing technology industries, a variety of portable electronic devices such as notebook computers, mobile phones, personal digital assistants (PDAs) or small-size liquid crystal display (LCD) continues to make progress. Wireless TV programs can be shown through these portable electronic devices in mobile environments. For example, the user can watch TV programs through a notebook computer by installing a built-in or external TV tuner card to receive wireless TV signals by an antenna device of the TV tuner card. In other conditions, personal digital assistants or mobile phones such as third generation (3G) mobile phones receive wireless TV signals via wireless network service provided by individual telecommunication company. 
         [0005]    A broadcast station generally issues wireless TV signals at specific frequency which should be received at the specific frequency in specific area. For a specific TV channel, it is possible that different broadcast stations issue the corresponding wireless TV signals at different frequencies. When the audience crosses the boundary between two areas respectively covered by two broadcast stations, the receiver device may fail to receive the wireless TV signals since the frequency for the same TV channel varies in the first broadcast area and the second broadcast area. 
         [0006]      FIG. 1  is a schematic diagram illustrating a vehicle crossing a boundary between two broadcast areas. A mobile wireless receiver device (not shown) for receiving wireless TV signals is carried by the vehicle  10  and shows a wireless TV program of a channel. In the first area a 1 , the broadcast station  11  broadcasts the TV program by wireless signals at frequency of 512 MHz. In the second area a 2 , the broadcast station  12  broadcasts the same TV program by wireless signals at frequency of 587 MHz. 
         [0007]    In practice, the mobile receiver device can receive the wireless TV signals at frequency at both 521 MHz and 587 MHz in the overlap between the two broadcast areas a 1  and a 2 . In the non-overlapping area, however, only one frequency of 521 MHz and 587 MHz is acceptable to receive the wireless TV signals. Thus, when the vehicle leaves the first broadcast area a 1  and enters the broadcast area a 2 , the wireless TV program that the user is watching cannot be properly displayed. 
         [0008]    Another similar experience of listening to broadcast program on the radio is taken as an example. For power or authority consideration, radio signals are issued at different frequencies in different areas. The listener should adjust the receiving frequency to listen to a specific channel on the radio when he drives on freeway to pass several areas. Further, it is inconvenient since the listener has to know the receiving frequency of the specific channel in the areas in advance. 
         [0009]    Different countries or regions have different broadcasting standards of wireless digital television. Hence, moving through different countries or regions will encounter the same problem in receiving wireless digital TV signals. For example, there are many countries and regions in the European continent and American. The user of the mobile receiver device is likely to pass through different countries and regions in the continent. Such problem occurs frequently if some countries or regions have smaller territory areas. Referring back to  FIG. 1 , the first broadcast area a 1  and the second broadcast area a 2  may represent two adjacent countries or two adjacent regions with different broadcasting standards. When a specific channel is broadcast in both areas, the receiving frequencies are usually different in these areas. 
         [0010]    A method has been proposed to solve this problem by full-frequency scan. The wireless receiver device auto-scans the channels in the second area a 2  and updates the information. The user browses the updated information and selects the desired channel. Since the scanning and updating steps take much time, it is inconvenient that the scanning and updating steps should be done as long as the user crosses the boundary between two broadcast areas. 
       SUMMARY OF THE INVENTION 
       [0011]    The present invention provides a method and a device for receiving wireless broadcast signals. The device can automatically adjust receiving frequency to properly receive the wireless broadcast signals when the device passes through different broadcast areas. 
         [0012]    In accordance with an aspect of the present invention, a method for receiving wireless broadcast signals is applied to a device storing therein a first information table and a second information table. The method includes steps of: receiving a first wireless broadcast signal at a first frequency contained in the first information table and presenting contents represented by the first wireless broadcast signal when the device is positioned in a first broadcast area; automatically searching for a second frequency in the second information table when the device is positioned in a second broadcast area wherein the second frequency corresponds to the information associated with the first frequency in the first information table; and receiving a second wireless broadcast signal at the second frequency and presenting contents represented by the second wireless broadcast signal. 
         [0013]    In accordance with another aspect of the present invention, a device receiving a first wireless broadcast signal in a first broadcast area and a second wireless broadcast signal in a second broadcast area is provided. The device includes a positioning module for providing a current position information; a memory storing a first information table and a second information table wherein the first information table includes at least a first frequency and the second information table includes at least a second frequency; a signal-receiving and processing module for receiving and processing the first wireless broadcast signal and the second wireless broadcast signal; a processor controlling the signal-receiving and processing module to receive the first wireless broadcast signal at the first frequency when the device is positioned in the first broadcast area and receive the second wireless broadcast signal at the second frequency when the device is positioned in the second broadcast area according to the current position information, and then processing and outputting the wireless broadcast signal; and a client terminal for presenting the signal outputted from the processor. The processor searches for the second frequency in the second information table according to the channel information corresponding to the first frequency in the first information table. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    The above contents of the present invention will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed description and accompanying drawings, in which: 
           [0015]      FIG. 1  is a schematic diagram illustrating two broadcast stations issuing wireless TV signals in two broadcast areas; 
           [0016]      FIGS. 2A and 2B  are schematic diagrams showing the use of a device for receiving wireless broadcast signals according to a preferred embodiment of the present invention; 
           [0017]      FIG. 3  is a schematic functional block diagram illustrating the device for receiving wireless broadcast signals according to the present invention; 
           [0018]      FIG. 4  is a flowchart illustrating a method for receiving wireless broadcast signals applied to the device of  FIGS. 2A and 2B ; 
           [0019]      FIGS. 5A and 5B  are schematic diagrams showing the use of a device for receiving wireless broadcast signals according to another preferred embodiment of the present invention; and 
           [0020]      FIG. 6  is a flowchart illustrating a method for receiving wireless broadcast signals applied to the device of  FIGS. 5A and 5B . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0021]      FIGS. 2A and 2B  are schematic diagrams showing the use of a device for receiving wireless broadcast signals according to a preferred embodiment of the present invention. A TV program of a specific channel is broadcast by the first broadcast station  11  in the first broadcast area a 1  and the second broadcast station  12  in the second broadcast area a 2 . The receiving frequencies of the wireless broadcast signals are different in these two broadcast areas a 1  and a 2 . A device of the present invention is carried by a vehicle  10  while there is a TV program presented by the device. The user cannot watch the TV program when the vehicle  10  leaves the first broadcast area a 1  and enters the second broadcast area a 2  due to incorrect receiving frequency. 
         [0022]    A positioning technology is used to detect the current position of the device. The device automatically adjusts the receiving frequency to receive the wireless broadcast signals according to the current position. Please refer to  FIG. 3 , a schematic functional block diagram illustrating the device  20  for receiving wireless broadcast signals according to the present invention. The device  20  is installed or disposed in the vehicle  10 . In an embodiment, the device  20  involves a mobile digital television or a notebook computer with a built-in or external TV turner card. 
         [0023]    The device  20  for receiving wireless broadcast signals includes a signal-receiving and processing module  21  for receiving and processing the wireless broadcast signals, e.g. digital TV signals or digital radio signals, so that the device  20  can present wireless TV program or radio program. The device  20  further includes a positioning module  22  for receiving a positioning signal issued by a satellite positioning system such as global positioning system (GPS). For example, the current position is obtained from a satellite positioning signal issued from the satellite  20  in  FIGS. 2A and 2B . 
         [0024]    As shown in  FIG. 3 , the signal-receiving and processing module  21  includes an antenna  211  for receiving the wireless broadcast signals and a tuner  212  for tuning the received signals. If the wireless signals are digital signals, a demodulator  213  is provided for demodulating the signals. Then, a decoder  214  decodes the signals and performs format conversion. The positioning module  22  includes an antenna  221  for receiving the satellite positioning signal from the satellite  30 , and a tuner  222  for tuning the received satellite positioning signal. If the positioning signal is an analog signal, an analog-to-digital converter (not shown) is provided for format conversion. Then, a demodulator  223  demodulates the signal. The signal-receiving and processing module  21  is a basic module of a digital TV tuner card or a digital television, and the positioning module  22  is a basic module of a client-end device of a satellite positioning system. Hence, the details of these modules  21  and  22  aren&#39;t explained hereinafter. 
         [0025]    The device  20  for receiving the wireless broadcast signals further includes a processor  23  designed for processing the wireless broadcast signals and the satellite positioning signal. The satellite positioning signal is processed to provide the information of the current position of the device  20 . Hence, the device  20  gets the information including the longitude and latitude of the vehicle  10  and in which broadcast area the vehicle  10  is positioned. Furthermore, after the processor  23  processes the wireless broadcast signals, the data such of video data or audio data transmitted by the wireless broadcast signals are outputted to a client terminal  25 . For example, video data are shown on a monitor and audio data are played by a radio. 
         [0026]    The memory  24  stores many information and parameters associated with every broadcast area. The memory  24  is implemented by a hard disc or a flash memory which can keep stored data without power. Please refer back to  FIGS. 2A and 2B . For a specific channel, the first broadcast station  11  in the first broadcast area a 1  and the second broad cast station  12  in the second broadcast area a 2  transmit wireless broadcast signals at different frequencies. Thus, a first information table (TABLE 1) associated with the first broadcast area a 1  and a second information table (TABLE 2) associated with the second broadcast area a 2  are stored in the memory  24 . 
         [0000]    
       
         
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
             
             
               
                   
                 HBO 
                 473 MHz 
               
               
                   
                 CNN 
                 485 MHz 
               
               
                   
                 FIBA 
                 521 MHz 
               
               
                   
                 ABC 
                 563 MHz 
               
               
                   
                 ABCsport 
                 611 MHz 
               
               
                   
                   
               
             
          
         
       
     
         [0000]    
       
         
               
               
               
             
           
               
                   
                 TABLE 2 
               
               
                   
                   
               
             
             
               
                   
                 ESPN 
                 479 MHz 
               
               
                   
                 CNN 
                 485 MHz 
               
               
                   
                 FIBA 
                 587 MHz 
               
               
                   
                   
               
             
          
         
       
     
         [0027]    TABLE 1 shows the channels and corresponding receiving frequencies in the first broadcast area a 1 , and TABLE 2 shows the channels and corresponding receiving frequencies in the second broadcast area a 2 . The channels may be TV channels or radio channels. The information table may contain channel frequency, channel identifier, channel name and the like. In digital television application, the information may include channel information or program information in a streaming data. The information that the information table may contain isn&#39;t entirely listed herein. In this embodiment, only part information is listed in the information table for concise purpose. The first information table (TABLE 1) contains five channels and associated information, while the second information table (TABLE 2) contains three channels and associated information. 
         [0028]    In this embodiment, in the first broadcast area a 1 , channel FIBA has first wireless broadcast signals at a first frequency of 521 MHz, but has second wireless broadcast signals at a second frequency of 587 MHz in the second broadcast area a 2 . The first wireless broadcast signals and the second wireless broadcast signals represent the same broadcast content. When the vehicle  10  leaves the first broadcast area a 1  and enters the second broadcast a 2 , the receiving frequency should be changed from 521 MHz into 587 MHz for properly receive the wireless broadcast signals. 
         [0029]    Please be noted that the information in the information tables are collected and arranged in advance. The information tables are loaded into the memory  24  so that the device can automatically adjust the receiving frequency according to the current position obtained from the positioning module. 
         [0030]    Furthermore, in some broadcast areas (regions or countries) the information, e.g. channel titles, channel identifiers, or channel receiving frequencies, may be adjusted or changed occasionally. The user may update the information tables to get the latest information. One approach is to load the information tables into the memory  24  by executing an application program through network or storage media such as optical disc or floppy disk containing the latest information provided by the producer or supplier of the device  20 . 
         [0031]    Please refer  FIG. 4 , a flowchart illustrating a method for receiving wireless broadcast signals according to a first embodiment of the present invention. The vehicle  10  is moving from the first broadcast area a 1  toward the second broadcast area a 2 . At step S 11 , the device  20  detects that the vehicle  10  is located in the first broadcast area a 1  according to the current position information. Hence, the device  20  receives the wireless broadcast signals based on the first information table (TABLE 1). In this embodiment, the device receives the wireless broadcast signals of channel FIBA issued from the first broadcast station  11  at the first frequency of 521 MHz. When the device  20  detects that the current position changes and the vehicle  10  enters the second broadcast area a 2  at step S 12 , the processor  23  automatically loads the second information table (TABLE 2) from the memory  24  for comparison with the first information table (TABLE 1) at step S 13 . 
         [0032]    At step  14 , the processor  23  finds out the channel title, i.e. channel FIBA, or channel identifier corresponding to the first receiving frequency (512 MHz) according to the first information table (TABLE 1). Then, the processor  23  searches the second information table (TABLE 2) to find out the second receiving frequency (587 MHz) corresponding the same channel title, i.e. channel FIBA, or channel identifier. Since the channel title or channel identifier is unique, it is impossible that any two channels have the same channel title and channel identifier. If the information tables are collected thoroughly, the processor  23  can accurately search the corresponding receiving frequency according to the current position. 
         [0033]    At step  15 , after the second receiving frequency (587 MHz) is determined, the signal-receiving and processing module  21  receives the second wireless broadcast signals of the same channel FIBA issued from the second broadcast station  12  at the second receiving frequency in the second broadcast area a 2 . Since the first wireless broadcast signals and the second wireless broadcast signals represent the same contents in channel FIBA, this transformation doesn&#39;t affect the play of the TV/radio program. The receiving frequency is automatically changed from the first frequency (521 MHz) into the second frequency (587 MHz) without manual operation. 
         [0034]    In the first embodiment, the two broadcast areas doesn&#39;t overlap.  FIGS. 5A and 5B  show that there is an overlapping area a 3  between the two broadcast areas a 1  and a 2 . When the vehicle  10  is positioned in the overlapping area a 3 , the first receiving frequency and the second receiving frequency are allowed to be used to receive the wireless broadcast signals. 
         [0035]    Please refer to  FIG. 6 , a flowchart illustrating a method for receiving wireless broadcast signals according to a second embodiment of the present invention. The vehicle  10  is moving from the first broadcast area a 1  toward the second broadcast area a 2 . At step S 21 , the device  20  detects that the vehicle  10  is located in the first broadcast area a 1  according to the current position information. Hence, the device  20  receives the wireless broadcast signals based on the first information table (TABLE 1). In this embodiment, the device receives the wireless broadcast signals of channel FIBA issued from the first broadcast station  11  at the first frequency of 521 MHz. 
         [0036]    When the device  20  detects that the current position changes and the vehicle  10  is positioned in the overlapping area a 3  at step S 22 , the processor  23  automatically loads the second information table (TABLE 2) from the memory  24  for comparison with the first information table (TABLE 1) at step S 23 . Before the second receiving frequency is checked as the correct frequency, the processor doesn&#39;t remove the first information table (TABLE 1). 
         [0037]    A broadcast area of a broadcast station is always clearly defined. For example, the broadcast area may be defined by the location of the broadcast station with a broadcast radius or defined by longitude and latitude data. Hence, the processor  23  can determine whether the vehicle is in the overlapping area a 3  between the two broadcast areas a 1  and a 2  or not according to the current position information obtained from the satellite positioning system. 
         [0038]    Furthermore, the designer may define the overlapping area a 3  between the two broadcast areas beforehand and loads the related information into the memory by executing an application program. The designer or user can adjust the definition of the overlapping area a 3  to make sure that a second receiving frequency has been found out before the first wireless broadcast signals aren&#39;t properly received anymore. 
         [0039]    In particular, when the vehicle  10  is positioned in the overlapping area a 3  between the two broadcast areas a 1  and a 2 , the device  20  alternately receives the first wireless broadcast signals and the second wireless broadcast signals to find out the signals with the better quality. The second receiving frequency is obtained at step S 24  which is similar to the step S 14  of the first embodiment. When the current position is positioned in the overlapping area a 3 , the processor  23  may prefer receiving the first wireless broadcast signals at the first frequency of 521 MHz or alternately receive the first wireless broadcast signals at the frequency of 521 MHz and the second wireless broadcast signals at the frequency of 587 MHz, both belongs to the same channel, i.e. channel FIBA (step S 25 ). Since the first and second wireless broadcast signals represent the same content in channel FIBA, the device  20  can select ones of the first and second wireless broadcast signals. 
         [0040]    The power of the wireless broadcast signals decreases with the distance to the broadcast station. If the current position information indicates that the vehicle  10  moves toward the second broadcast area a 2 , the power of the first wireless broadcast signals gradually decreases and that of the second wireless broadcast signals gradually increases. Hence, the device  20  can be designed to receive the second wireless broadcast signals in the overlapping area a 3 . 
         [0041]    According to the above-described concept, the second receiving frequency is obtained and selected by auto search and auto selection without manual operation. It is unnecessary for the user to know where the vehicle  10  is. The device  20  can receive specific signals at a proper frequency and doesn&#39;t affect the play of the program. 
         [0042]    After the vehicle  10  entirely leaves the first broadcast area a 1  and enters the second broadcast area a 2 , the device  20  receives the wireless broadcast signals according to the information in the second information table (TABLE 2) instead of the first information table (TABLE 1). On the contrary, if the vehicle  10  moves from the second broadcast area a 2  toward the first broadcast a 1 , we just have to exchange the “first” and “second” words in the description to reverse the condition. The applicable conditions further include that the vehicle  10  enters a third broadcast area (not shown) or the overlapping area are located among more than two broadcast areas. 
         [0043]    Hence, when an audience or a listener travels many countries or regions over the European continent or American, he can watch digital TV programs or listen to digital radio programs in the vehicle even though the receiving frequencies of the wireless broadcast signals varies in different broadcast areas. The present invention provides an automatic receiving method without manual operation to solve the problems encountered in the prior arts. The present invention is also applied to satellite TV programs because the frequencies of different satellites may vary. The device of the present invention can be utilized, provided that the signal-receiving and processing module is capable of receiving the satellite TV signals, to receive satellite TV programs broadcast by different satellite systems. 
         [0044]    While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not to be limited to the disclosed embodiment. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.