Patent Publication Number: US-8121715-B2

Title: Radio signal transmitter and related method and multimedia system for an audio source generator

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a radio signal transmitter, related method, and related multimedia system for an audio source generator, and more particularly, to a radio signal transmitter, related method, and related multimedia system for avoiding degradation of audio output quality or influence on other people when receiving broadcasting programs. 
     2. Description of the Prior Art 
     Portable multimedia players, such as MP3 (MPEG-1 Audio Layer 3) or CD (Compact Disc) players, etc., can output video and audio signals at any time and in any place. Generally, a portable multimedia player comprises a specific audio output interface for outputting audio signals to an external audio player. For example, an MP3 portable player includes a 3.5 mm audio jack in order to output audio signals to audio output devices, such as speakers or headphones. 
     Therefore, using the portable multimedia player, a user can enjoy multimedia interaction on the go. However, in some cases, portable multimedia player may not output audio signals through the predetermined output interface. For example, a vehicle multimedia player can be utilized for playing CD, AM, or FM broadcasting programs, etc., but the vehicle multimedia player may not have external interfaces or have improper external interfaces, which do not conform to a format of the use&#39;s MP3 player. In other words, the user cannot play audio signals in the MP3 player via the vehicle multimedia player. In such a condition, in order to expand functions of the vehicle multimedia player, the prior art provides an electronic device, which outputs audio signals to the vehicle multimedia player via frequency modulation (FM) channel. 
     Please refer to  FIG. 1 .  FIG. 1  is a schematic diagram of a prior art FM output device  10 . The FM output device  10  is installed between an audio source generator  12  and a vehicle multimedia player  14 , and utilized for transforming audio signals provided by the audio source generator  12  into FM signals for the vehicle multimedia player  14 . The audio source generator  12  can be an MP3 player or a CD player, and comprises an audio generating device  120  and an output interface  122 . The audio generating device  120  outputs audio signals to the FM output device  10  via the output interface  122  (e.g. 3.5 mm audio jack). The FM output device  10  includes a receiving interface  100 , a modulation unit  102 , a transmission antenna  104 , and a switching unit  106 . The receiving interface  100  can be connected with the output interface  122  for receiving the audio signals provided by the audio source generator  12 . The modulation unit  102  is coupled to the receiving interface  100 , and utilized for modulating the audio signals into FM signals, so as to emit the FM signals via the transmission antenna  104 . The switching unit  106  is utilized for switching frequencies of the FM signals outputted from the modulation unit  102 . On the other hand, the vehicle multimedia player  14  includes an audio player device  140 , a demodulation unit  142 , a reception antenna  144 , and a switching unit  146 . After the FM output device  10  outputs FM signals via a specific frequency, a user can switch a frequency of the demodulation unit  142  through the switching unit  146 , so that the demodulation unit  142  can receive the FM signals provided by the FM output device  10  via reception antenna  144 , and demodulate the FM signals. Then, the audio player device  140  can play the demodulated FM signals. 
     Therefore, using the FM output device  10 , the user can adjust the operating frequencies of the modulation unit  102  and the demodulation unit  142  to the same frequency via the switching units  106 ,  146 , so as to play audio signals provided by the audio source generator  12  through the vehicle multimedia player  14 . However, such operating approach mentioned above has its limitation; that is, the user must avoid adjusting the operating frequencies of the modulation unit  102  and the demodulation unit  142  to a frequency of a broadcasting program. If the user adjusts the operating frequencies of the modulation unit  102  and the demodulation unit  142  to a frequency of a broadcasting program, signals of the broadcasting program will interfere with the FM signals outputted from the FM output device  10  and affect the output effect of the vehicle multimedia player  14 . Meanwhile, the FM signals outputted from the FM output device  10  may affect neighboring vehicle multimedia players when receiving the broadcasting programs. However, there are many broadcasting programs in the air at the same time, and frequencies used by the broadcasting programs may be different in different area, so that the user may easily adjust the operating frequencies of the modulation unit  102  and the demodulation unit  142  to a wrong frequency, i.e. a frequency utilized for a broadcasting program, causing degradation of the audio output quality, or influence on other people when receiving broadcasting programs. 
     In short, using the prior art FM output device  10 , the user blindly chooses the operating frequencies of the modulation unit  102  and the demodulation unit  142  without any reference, leading to degradation of audio output quality, influence on other people when receiving broadcasting programs, as well as inconvenience. 
     SUMMARY OF THE INVENTION 
     It is therefore a primary objective of the claimed invention to provide a radio signal transmitter, related method and related multimedia system for an audio source generator. 
     The invention discloses a radio signal transmitter for an audio source generator, which comprises a reception antenna for receiving a plurality of broadcasting signals, a decision unit coupled to the reception antenna for determining intensities of the plurality of broadcasting signals received by the reception antenna, a selection unit coupled to the decision unit for determining an operating frequency according to a decision result of the decision unit, a modulation unit coupled to the selection unit and the audio source generator for transforming an audio signal provided by the audio source generator into a broadcasting signal according to the operating frequency determined by the selection unit, and a transmission antenna coupled to the modulation unit for emitting the broadcasting signal outputted from the modulation unit in the air. 
     The invention further discloses a method for outputting an audio signal of an audio source generator, which comprises receiving a plurality of broadcasting signals, determining intensities of the plurality of broadcasting signals, determining an operating frequency according to the intensities of the plurality of broadcasting signals, transforming the audio signal provided by the audio source generator into a broadcasting signal according to the operating frequency, and emitting the broadcasting signal. 
     The invention further discloses a multimedia system, which comprises an audio source generator for outputting an audio signal, an audio player device for receiving and playing frequency modulation broadcasting signals, and a radio signal transmitter coupled to the audio source generator, the radio signal transmitter comprises a receiving end coupled to the audio source generator for receiving the audio signal provided by the audio source generator, a reception antenna for receiving a plurality of broadcasting signals, a decision unit coupled to the reception antenna for determining intensities of the plurality of broadcasting signals received by the reception antenna, a selection unit coupled to the decision unit for determining an operating frequency according to a decision result of the decision unit, a modulation unit coupled to the receiving end and the selection unit for transforming the audio signal provided by the audio source generator into a broadcasting signal according to the operating frequency determined by the selection unit, and a transmission antenna coupled to the modulation unit for emitting the broadcasting signal outputted from the modulation unit to the audio player device in order to play the broadcast signal by the audio player device. 
     These and other objectives of the invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of a frequency modulation output device in the prior art. 
         FIG. 2  is a schematic diagram of a multimedia system according to an embodiment of the invention. 
         FIG. 3  is a schematic diagram of a procedure according to an embodiment of the invention. 
         FIG. 4  is a schematic diagram of the selection unit shown in  FIG. 2  according to an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     Please refer to  FIG. 2 .  FIG. 2  is a schematic diagram of a multimedia system  20  according to an embodiment of the invention. The multimedia system  20  includes an audio source generator  200 , an audio player device  202 , and a radio signal transmitter  204 . The audio source generator  200  is utilized for outputting audio signals. The audio source generator  200  can be an electronic device capable of outputting audio signals, such as MP3 player, CD player, PDA, etc., and is not limited to any of them. The audio player device  202  is capable of receiving and playing broadcasting signals, which can be a vehicle or a home-use multimedia player, and is not limited to any of them. The radio signal transmitter  204  is coupled to the audio source generator  200 , and utilized for modulating the audio signals generated by the audio source generator  200  into broadcasting signals and emitting the broadcasting signals for the audio player device  202  to play the audio signals. 
     In  FIG. 2 , the audio signal transmitter  204  includes a reception end  206 , a reception antenna  208 , a decision unit  210 , a selection unit  212 , a modulation  214  and a transmission antenna  216 . The receiving end  206  conforms to a format of a specific connection interface, and utilized for connecting to the audio source generator  200  in order to receive the audio signals outputted from the audio source generator  200 . The decision unit  210  is coupled to the reception antenna  208 , and utilized for receiving broadcasting signals via the reception antenna  208  in order to determine intensities of the broadcasting signals. The selection unit  212  is coupled to the decision unit  210 , and utilized for determining an operating frequency according to a decision result of the decision unit  210 . The modulation unit  214  is coupled to the receiving end  206 , the selection unit  212 , and the transmission antenna  216 , and utilized for transforming the audio signals provided by the audio source generator  200  into broadcasting signals according to the operating frequency determined by the selection unit  212 , in order to emit to the audio player device  202  via the transmission antenna  216  and play the audio signals by the audio player device  202 . 
     As to an operating procedure of the radio signal transmitter  204  shown in  FIG. 2 , please refer to  FIG. 3 .  FIG. 3  is a schematic diagram of a procedure  30  according to an embodiment of the invention. The procedure  30  is utilized for outputting the audio signals provided by the audio source generator  200  in the radio signal transmitter  204 , and comprises the following steps: 
     Step  300 : Start. 
     Step  302 : Receive a plurality of broadcasting signals from the reception antenna  208 . 
     Step  304 : Determine intensities of the plurality of broadcasting signals via the decision unit  210 . 
     Step  306 : Determine an operating frequency according to the intensities of the plurality of broadcasting signals via the selection unit  212 . 
     Step  308 : Transform the audio signal provided by the audio source generator  200  into a broadcasting signal via the modulation unit  214  according to the operating frequency. 
     Step  310 : Emit the broadcasting signal via the transmission antenna  216 . 
     Step  312 : End. 
     As can be seen, the invention is able to determine a frequency of a broadcasting signal outputted from the modulation unit  214  according to the intensities of the broadcasting signals. Preferably, the invention can choose a broadcasting frequency with lower or the lowest power as the operating frequency of the modulation unit  214 , in order to avoid degradation of audio output quality due to broadcasting interference or influence on other people when receiving broadcasting programs. 
     Note that, the multimedia system  20  is an exemplary embodiment of the invention, and those skilled in the art can make alternations and modifications accordingly. For example, please refer to  FIG. 4 .  FIG. 4  is a schematic diagram of the selection unit  212  shown in  FIG. 2  according to an embodiment of the invention. The selection unit  212  includes a display unit  400 , an input interface  402 , and a storage unit  404 . The display unit  400  is coupled to the decision unit  210 , and utilized for displaying the decision result of the decision unit  210 , such that the user is capable of outputting a control signal through the input interface  402  according to the decision result displayed on the display unit  400 , in order to determine the operating frequency of modulation unit  214 . Preferably, the display unit  400  displays frequencies corresponding to broadcasting signals having intensities smaller than a predetermined value among the plurality of broadcasting signals received by the reception antenna  208  according to the decision result of the decision unit  210 . The predetermined value can be a fixed value or can change according to the intensities of the plurality of broadcasting signals, such as the average of the intensities of the plurality of broadcasting signals. Besides, the storage unit  404  is capable of storing the determination result of the user as reference. 
     Moreover, multimedia system  20  can further include a storage unit for storing the decision result of decision unit  210  or available frequencies predetermined by the user as reference. 
     Therefore, in the multimedia system  20 , the radio signal transmitter  204  is capable of providing information about the operating frequency for the user according to the intensities of the plurality of broadcasting signals, so as to avoid degradation of audio output quality due to interference of broadcasting programs or influence on other people when receiving broadcasting programs. Note that, in the invention, the radio signal transmitter  204  preferably applies the FM technique to modulate the audio signals outputted by the audio source generator  200 , and certainly, those skilled in the art can utilize other modulation approaches to modulate the audio signals. 
     In conclusion, the user can choose a frequency with the least interference as a modulation frequency, in order to avoid degradation of audio output quality or influence on other people when receiving broadcasting programs. 
     Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention.