Patent Publication Number: US-2009230918-A1

Title: Wireless signal processing circuit utilizing charging module as charger and antenna via single connecting port

Description:
BACKGROUND OF THE INVENTION  
     1. Field of the Invention 
     The present invention relates to a wireless signal processing circuit, and more particularly, to a wireless signal processing circuit that utilizes a single connecting port and a charger electrically coupled to the connecting port to perform charging and antenna transmission. 
     2. Description of the Prior Art 
     As well as planning a shortest route that connects a starting point and destination point, smart navigation systems can also collect and analyze the latest traffic information, which is then combined with graphic data in a data base to provide a route that avoids delays and traffic jams. The utilization efficiency of vehicles and roads is therefore improved. The above function is achieved with the help of the Traffic Message Channel (TMC), which is a frequency modulation (FM) system that broadcasts in-time traffic and weather information by embedding digital codes in FM signals. Provided a navigation system is equipped with a TMC decoding chip, in-time road situations and related information can be extracted from the received FM signal. 
     Conventionally, as shown in  FIG. 1 , a print circuit board of a navigation device has an antenna port  110  and a charge port  120  for connecting to an external antenna  115  and an external charger  125  respectively. A TMC chip  100  obtains stable power from the charger  125  via the charge port  100 , and receives the FM signal of the Traffic Message Channel from the antenna  115  via the antenna port  110 . The navigation device generally uses an earphone jack to serve as the antenna port  110 , or has a separate earphone jack for the antenna. Therefore, the antenna  115  needs to comply with the earphone standard of the navigation device. 
     SUMMARY OF THE INVENTION  
     Since a conventional navigation device requires an antenna and a charger to receive signals and charges respectively, the antenna and the charger necessitate additional expenses. In order to reduce cost and increase utilization convenience, one objective of the present invention is to provide a wireless signal processing circuit that can perform charging and antenna transmission by one charger. When the wireless signal processing circuit is implemented in a TMC chip, the TMC chip does not require the external antenna, but utilizes the charger to provide both an antenna function and a power supply. 
     According to one exemplary embodiment of the invention, a wireless signal processing circuit is provided. The wireless signal processing circuit includes a processing module and an inductor. The processing module is for processing a wireless signal, and includes a connecting port to transmit or receive the wireless signal. The inductor is coupled to the connecting port and the processing module. When the connecting port is coupled to a charging module, the charging module draws power from an external power supply via the connecting port to the processing module, and serves as an antenna to receive or transmit the wireless signal. 
     These and other objectives of the present 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 block diagram of a conventional print circuit board of a navigation system equipped with a TMC chip. 
         FIG. 2  shows a block diagram of a wireless signal processing circuit according to an exemplary embodiment of the present invention. 
         FIG. 3  shows a connection relationship between the charger, the connecting port and an external power supply when the charger is a car charger. 
     
    
    
     DETAILED DESCRIPTION  
     Please refer to  FIG. 2 , which is a diagram of a wireless signal processing circuit  200  according to an exemplary embodiment of the present invention. The wireless signal processing circuit  200  includes a processing module  210 , an inductor  220  and a connecting port  230 . The processing module  210  is utilized to process a wireless signal that is received or transmitted via the connecting port  230 . In addition, the processing module  210  receives power from an external power supply by a charger  240  via the connecting port  230 . 
     The connecting port  230  complies with one of the conventional standards, such as USB, IEEE 1394, RS-232, SCSI, EPP, ECP and LPT. One output terminal of the charger  240  complies with the connecting port  230  so as to be electrically coupled to the connecting port  230 . In one embodiment, as shown in  FIG. 3 , the charger  240  can be a car charger having a USB output plug  242 , which is used to connect to the connecting port  230 . The charger  240  further has an input plug  244  that is used to connect to a cigarette lighter port  260  in car. Therefore, through the connecting port  230 , the power drawn by the charger  240  is provided to the processing module  210 . Moreover, the charger  240  plugged in the connecting port  230  can be utilized as an antenna: the processing module  210  sends the processed wireless signal through the connecting port  230  to the charger  240  to be transmitted, or receives a wireless signal received by the charger  240  through the connecting port  230 . 
     The main functionalities of the inductor  220  are filtering and rating current. That is, the wireless signal processing circuit  200  selects a properly rated current inductor to perform charging, and selects a proper inductance to control the received frequency band. In general, when the charger  240  is a car charger having an output current equal to 1 A, the rated current of the inductor  220  must not be less than 1 A, otherwise the inductor  220  may be burned out during charging. Please note that the rated current and the inductance of the inductor  220  can be different depending on the system requirements. 
     In one embodiment, the wireless signal processing circuit  200  is implemented in a navigation system, and the processing module  210  is a TMC chip that receives an FM signal, decodes the traffic message from the FM signal, and provides the traffic message to the other processing circuits in the navigation device in order to provide an in-time road situation to the user. The inductance of the inductor  220  is selected according to the frequency band used by the traffic message channel. The inductor  220  can be disposed outside the TMC chip or be integrated within the TMC chip. In one embodiment, the processing module  210 , the inductor  220  and the connecting port  230  are all disposed inside a housing  250  of the navigation device, while the charger  240  is outside the housing  250 . Compared to the prior art, the navigation device in this embodiment can be charged and receive FM signals by connecting to the charger  240  only. Because the TMC broadcast is implemented by embedding digital codes in FM signals, i.e. the TMC chip  210  can provide TMC functionality after the digital codes are received and decoded, and the message quality is good enough for the TMC chip  210  by using the charger  240  as an antenna. 
     The present invention couples the inductor  220  to the connecting port  230 , and performs charging and signal receiving/transmitting through the same connecting port  230 . The antenna is no longer required, unlike in the prior art, and the charger  240  can replace the antenna directly, thereby significantly saving the cost and improving the utilization convenience. 
     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.