Patent Abstract:
Provided are an apparatus and a method of improving the sound quality of an FM radio signal in a portable terminal. The apparatus includes: an FM radio module receiving an FM radio signal; an application processor processing an application program for playing an audio signal; a switch selectively switching to transmit an audio signal processed in the application processor or the FM radio signal received through the FM radio module into an audio sub system; the audio sub system decoding and post-processing the audio signal or the FM signal, which is provided through the switch; and an amplifier amplifying the signal decoded and post-processed in the audio sub system and output the amplified signal to an external.

Full Description:
CLAIM OF PRIORITY 
     This application claims the benefit of an earlier application filed in the Korean Intellectual Property Office on Feb. 4, 2009 and assigned Serial No. 10-2009-0008847, the contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to an FM radio, and in particular, to an apparatus for improving the sound quality of an FM radio in a portable terminal. 
     2. Description of the Related Art 
     The portable terminal becomes extensively used due to convenience of its portability. Accordingly, portable terminal manufacturers have been currently developing portable terminals for supporting additional services (such as wireless internet, a camera, an MP3 player, and an FM radio) to attract even more consumers. 
     If the portable terminal supports an FM radio function, it typically includes an FM radio module for receiving an FM radio signal. In this case, the portable terminal amplifies the received FM radio signal through the FM radio module, and outputs the amplified signal through a speaker or an earphone. 
     As mentioned above, the portable terminal including an FM radio function may tune the volume of an FM radio signal through a gain adjustment of an amplifier. However, the FM radio signal is vulnerable to noise in current portable terminals. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide an apparatus and a method of improving the sound quality of an FM radio signal in a portable terminal. 
     Another object of the present invention is to provide an apparatus and a method of improving the sound quality of an FM radio signal by a post-processing an FM radio signal in a portable terminal. 
     According to an aspect of the present invention, an apparatus for receiving an FM radio signal in a portable terminal includes: an FM radio module receiving an FM radio signal; an application processor processing an application program for playing an audio signal; a switch switching to transmit an audio signal processed in the application processor or the FM radio signal received through the FM radio module into an audio sub system; the audio sub system decoding and post-processing the audio signal or the FM signal, which is provided through the switch; and an amplifier amplifying the signal decoded and post-processed in the audio sub system and output the amplified signal to an external. 
     According to another aspect of the present invention, a method of receiving an FM radio signal in a portable terminal includes: switching to transmit an FM radio signal received through the FM radio module into an audio sub system for decoding and post-processing a signal when an FM radio service is provided; switching to transmit an audio signal played in an application processor into the audio sub system when an audio signal is played; decoding and post-processing an FM radio signal or an audio signal, which is transmitted into the audio sub system through the switching; and amplifying the decoded and post-processed signal to output it to an external. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above features and advantages of the present invention will become more apparent to those skilled in the art from the following detailed description when taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is a view illustrating a configuration of a portable terminal for performing a post-processing on an FM radio signal according to the present invention; and 
         FIG. 2  is a view of a procedure for performing a post-processing on an FM radio signal in a portable terminal according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Preferred embodiments of the present invention will be described herein below with reference to the accompanying drawings. For the purposes of clarity and simplicity, detailed descriptions of well-known functions or constructions will be omitted as they would obscure the invention in unnecessary detail. Also, the terms used herein are defined according to the functions of the present invention. Thus, the terms may vary depending on user&#39;s or operator&#39;s intentions or practices. Therefore, the terms used herein must be understood based on the descriptions made herein. 
     Hereinafter, the present invention describes a technique for improving the sound quality of an FM radio signal in a portable terminal with an FM radio function. 
     According to the teachings of the present invention, the portable terminal performs a post-processing on an FM radio signal, which is received through an FM radio module, in order to improve the sound quality of the FM radio signal. For example, the portable terminal is configured as shown in  FIG. 1  to perform the post-processing on an FM radio signal. It should be noted that the configuration of an audio system of a portable terminal shown in  FIG. 1  with a communication function is for illustrative purposes, but may be identically applied to a portable terminal without having the communication function or may be applied to process signals other than FM radio signals. 
       FIG. 1  is a view illustrating a configuration of a portable terminal for performing a post-processing on an FM radio signal according to the present invention. 
     As shown in  FIG. 1 , the portable terminal is configured to include an audio system  100 , an analog codec  140 , an amplifier (AMP)  150 , an FM radio module  160 , a switch  170 , an application processor  180 , and a modem processor  190 . 
     The audio system  100  further includes a voice sub system  110  for processing a voice signal, an audio sub system  120  for processing an audio signal, and an analog front end (AFE)  130 . 
     The voice sub system  110  is configured to include a pre-processing unit  111 , an encoding unit  113 , a decoding unit  115 , and a post-processing unit  117 . 
     The pre-processing unit  111  performs pre-processing on a voice signal provided from the AFE  130  according to a predetermined pre-processing method. For example, the pre-processing unit  111  is configured to include a first pre-processing unit for removing echo, a second pre-processing unit for automatic gain control (AGC), a third pre-processing unit for automatic volume control (AVC), and a fourth pre-processing unit for noise suppressor (NS). The pre-processing unit  111  activates only a corresponding pre-processing unit according to a predetermined pre-processing method among the first to fourth pre-processing units in the pre-processing unit  111 , and then performs pre-processing on a voice signal provided from the AFE  130 . 
     The encoding unit  113  encodes a voice signal provided from the pre-processing unit  111  and outputs the encoded signal to the modem processor  190 . 
     The decoding unit  115  decodes a voice signal provided from the modem processor  190  and then outputs the decoded signal to the post-processing unit  117 . 
     The post-processing unit  117  performs the post-processing on a voice signal provided from the decoding unit  115  according to a predetermined post-processing method. For example, the post-processing unit  117  includes a first post-processing unit for performing filtering according to a pulse code modulation, a second post-processing unit for AGC, and a third post-processing unit for AVC. The post-processing unit  117  activates only a corresponding post-processing unit according to a predetermined post-processing method among the first to third post-processing units in the post-processing unit  117 , then performs the post-processing on a voice signal provided from the decoding unit  115 . 
     The audio sub system  120  is configured to include a pre-processing unit  121 , an encoding unit  123 , a decoding unit  125 , and a post-processing unit  127  in order to process an audio signal. 
     The pre-processing unit  121  performs pre-processing on an audio signal provided from the AFE  130  according to a predetermined pre-processing method. For example, the pre-processing unit  121  includes a first pre-processing unit for AGC and a second pre-processing unit for NS. The pre-processing unit  121  activates only a corresponding pre-processing unit according to a predetermined pre-processing method among the first and second pre-processing units in the pre-processing unit  111 , then performs the pre-processing on an audio signal provided from the AFE  130 . 
     The encoding unit  123  encodes an audio signal provided from the pre-processing unit  121  and outputs the encoded signal to the application processor  180 . 
     The decoding unit  125  decodes an audio signal or an FM radio signal, provided from the switch  170 , and then outputs the decoded signal to the post-processing unit  127 . 
     The post-processing unit  127  performs post-processing on an audio signal or an FM radios signal, provided from the decoding unit  125 , according to a predetermined post-processing method. For example, the post-processing unit  127  performs post-processing on an audio signal or an FM radios signal, provided from the decoding unit  125 , in order to perform an equalizer function. At this point, the post-processing unit  127  may include a plurality of post-processing units, each of which performs a post-processing function. 
     The AFE  130  converts a digital signal, provided from the voice sub system  110  and the audio sub system  120 , into an analog signal and outputs the converted signal into the analog codec  140 . At this point, the AFE  130  combines signals from the voice sub system  110  and the audio sub system  120  into one signal and then outputs it. 
     Additionally, the AFE  130  converts a digital signal, provided from the analog codec  140 , into an analog signal, and outputs the converted signal into the voice sub system  110  or the audio sub system  120 . 
     The analog codec  140  controls a gain of an analog signal. That is, the analog codec  140  controls a gain of a signal, provided from the AFE  130 , and then outputs it to the AMP  150 . In addition, the analog codec  140  controls a gain of an analog signal received through an input device, then outputs it to the voice sub system  110  or the audio sub system  120 . Here, an input device includes a microphone, a headset, or the like. 
     The AMP  150  amplifies an analog signal, provided from the analog codec  140 , and outputs it to a speaker or a headset. 
     The FM radio module  160  receives an FM radio signal. For example, the FM radio module  160  includes a pin grid array (PGA) module, an analog/digital converter (ADC), and a digital signal processor (DSP). 
     The switch  170  selectively switches an audio signal provided from the application processor  180  and an FM radio signal provided from the FM radio module  160  into the audio sub system  120  in response to a control of the application processor  180 . For example, while listening to MP3 music, the switch  170  switches to connect the application processor  180  with the audio sub system  120  in response to a control of the application processor  180 . Moreover, while providing an FM radio service, the switch  170  switches to connect the FM radio module  160  with the audio sub system  120  in response to a control of the application processor  160 . 
     The application processor  180  processes an application program for playing an audio signal that is encoded with an MP3 or advanced audio coding (AAC) format. 
     In addition, the application processor  180  controls the switch  170  to selectively switch an audio signal provided from the application processor  180  and an FM radio signal provided from the FM radio module  160  into the audio sub system  120  in response to a control of the application processor  180 . At this point, the application processor  180  switches to connect the application processor  180  with the audio sub system  120  when an audio signal is transmitted. 
     The modem processor  190  processes a voice signal that is received and transmitted for voice communication. 
     Hereinafter, a method of performing post-processing on an FM radio signal in a portable terminal will be described. 
       FIG. 2  is a view of a procedure for performing post-processing on an FM radio signal in a portable terminal according to an embodiment of the present invention. 
     Referring to  FIG. 2 , the portable terminal confirms whether an FM radio service is provided or not according to input information of a user in operation  201 . 
     If an FM radio service is provided, the portable terminal proceeds to operation  203  and activates an FM radio module to provide the FM radio service. 
     At this point, the portable terminal proceeds to operation  205  and then connects the FM radio module with an audio system. For example, the portable terminal controls the switch  170  to connect the audio sub system  120  with the FM radio module  160  shown in  FIG. 1 . 
     After the FM radio module is connected to an audio system, the portable terminal proceeds to operation  207  and confirms whether an FM radio signal is received or not through the FM radio module. 
     If the FM radio signal is received, the portable terminal proceeds to operation  209  and decodes the FM radio signal received through the FM radio module. For example, the portable terminal decodes the FM radio signal, received through the FM radio module, using the decoding unit  125  of the audio sub system  120  of  FIG. 1 . 
     Next, the portable terminal proceeds to operation  211 , and performs post-processing on the FM radio signal decoded in the operation  209  according to a predetermined post-processing method. For example, the portable terminal performs post-processing on the FM radio signal decoded in the operation  209 , using the post-processing unit  127  of the audio sub system  120  shown in  FIG. 1 . At this point, the portable terminal performs post-processing on the FM radio signal by selecting at least one of post-processing methods including equalizing, base enhancement, automatic volume limiting, high frequency band improvement, noise reduction, volume setting, and three-dimensional sound. 
     After the post-processing of the FM radio signal, the portable terminal proceeds to operation  213  and outputs the FM radio signal, which is post-processed in the operation  211 , through a speaker. 
     Next, the portable terminal terminates this algorithm. 
     As mentioned above, the portable terminal performs post-processing on an FM radio signal received through the FM radio module such that sound quality of the FM radio signal can be improved. 
     The above-described methods according to the present invention can be realized in hardware or as software or computer code that can be stored in a recording medium such as a CD ROM, an RAM, a floppy disk, a hard disk, or a magneto-optical disk or downloaded over a network, so that the methods described herein can be executed by such software using a general purpose computer, or a special processor or in programmable or dedicated hardware, such as an ASIC or FPGA. As would be understood in the art, the computer, the processor or the programmable hardware include memory components, e.g., RAM, ROM, Flash, etc. that may store or receive software or computer code that when accessed and executed by the computer, processor or hardware implement the processing methods described herein. 
     While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the scope of the invention is defined not by the detailed description of the invention but by the appended claims, and all differences within the scope will be construed as being included in the present invention.

Technology Classification (CPC): 7