JP3639571B2 - Portable viewing device - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a portable viewing device that can perform television viewing by terrestrial digital broadcasting and can perform a call by a portable call function.
[0002]
[Prior art]
In digital broadcasting using terrestrial waves, a transmission method called OFDM (Orthogonal Frequency Division Multiplexing) is used. In this OFDM transmission, the frequency band assigned to each channel is divided into 13 segments (frequency bands) and used, and different modulation schemes (secondary modulation schemes) can be selected. As a digital broadcast receiving apparatus that receives the broadcast wave, it is assumed that it is used as a portable apparatus provided with a receiving function in addition to a fixed installation type apparatus that is fixedly installed in a house. For this reason, it is considered to perform hierarchical transmission using a plurality of different transmission path encodings as well as broadcasting with a single transmission path encoding. In this hierarchical transmission, a maximum of three hierarchies are used, and there are a strong hierarchy, a middle hierarchy, and a weak hierarchy in order from the lowest required C / N ratio. Then, strong hierarchical broadcasting is performed for portable devices.
[0003]
In recent years, mobile phones and PHS phones are widely used, and it is conceivable that a portable viewing device is provided by mounting these mobile phone call functions and terrestrial digital broadcast receiving functions in a portable case.
[0004]
As a conventional apparatus, there is an apparatus that performs telephone reception and program recording control when a telephone call is received while watching a TV broadcast (see Patent Document 1).
[0005]
[Patent Document 1]
JP 2001-339648 A
[Problems to be solved by the invention]
However, mobile phones and PHS phones perform wireless communication (location registration processing) in order to inform the base station of their location, and for this reason, radio waves are transmitted even when a call is not being made. . Although this radio wave is different from the frequency of the TV broadcast radio wave, since the mobile call function unit and the broadcast reception function unit exist in the vicinity, there is a possibility that the reception of the TV broadcast may be hindered.
[0007]
In view of the above circumstances, an object of the present invention is to reduce a broadcast reception failure caused by position registration radio wave transmission in a mobile phone function in a portable viewing device equipped with a terrestrial digital broadcast reception function and a mobile call function. .
[0008]
[Means for Solving the Problems]
In order to solve the above problems, the portable viewing device of the present invention includes a broadcast receiving means for receiving a terrestrial digital broadcast and outputting video and / or audio, and a portable call means for making a call by transmitting and receiving radio waves. And means for notifying the mobile call means of a guard interval in the terrestrial digital broadcast, and the mobile call means executes position registration processing during the guard interval based on the notification. It is comprised so that it may do.
[0009]
With the above configuration, the location registration process is performed during the guard interval, so that the reception trouble of terrestrial digital broadcasting is reduced. Even if the radio wave transmission by the location registration process becomes noise and the guard interval cannot be detected, the synchronization can be maintained for a predetermined period, and therefore the influence by the failure to detect the above is small.
[0010]
The mobile call means may be configured to notify the broadcast receiving means when performing a location registration process. According to this, even if noise is superimposed on the guard interval, it is possible to determine that the noise is caused by the position registration process, and the influence on the demodulation process of the terrestrial digital broadcast in the broadcast receiving unit can be reduced.
[0011]
When the time required for the position registration process is longer than the guard interval, the position registration process is preferably performed over a plurality of guard intervals.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
[0013]
As shown in FIG. 1, the portable viewing device 2 has, for example, a vertically long and flat shape and is driven by a battery. The portable viewing device 2 receives the terrestrial digital broadcast, displays the video on the liquid crystal display panel 202, and outputs the sound from the earphone. Also, the encoded video / audio data is read from the memory card inserted into the slot 201, the video is displayed on the liquid crystal display panel 202, and the audio is output from the earphone. A touch panel 211 is pasted on the liquid crystal display panel 202, and a desired instruction can be given by operating the panel with a touch pen or the like. Note that operation buttons (play / pause, stop, feed, volume, etc.) relating to viewing are provided on the casing.
[0014]
The circuit configuration of the portable viewing device 2 will be described in detail with reference to FIG. MPEG4 bit stream data (encoded video / audio data) stored in the memory card 3 is supplied to the MPEG4 decoder 204 via the PCMCIA interface 220 and the system bus 213. The MPEG4 bit stream data stored in the SDRAM 219 which is a built-in memory is supplied to the MPEG4 decoder 204 via the system bus 213. The tuner 230 that receives the terrestrial digital broadcast takes out the MPEG4 bit stream data broadcast by the terrestrial digital broadcast and supplies it to the MPEG4 decoder 204 or records it in the memory card 3 or the SDRAM 219. 213. The MPEG4 decoder 204 decodes the bit stream data to obtain a quantization coefficient and a motion vector, and supplies video data obtained by performing inverse DCT transformation, motion compensation control based on the motion vector, and the like to the graphics controller 205. The graphics controller 205 performs processing such as color adjustment on video data (for example, R, G, B data). The graphics controller 205 also performs processing for displaying characters or the like (operation buttons, menu screens, EPG screens based on program information acquired from terrestrial digital broadcasts), etc., instructed to be output from the CPU 209 on the liquid crystal display panel 202. The audio decoder 206 receives the audio code data in the bit stream from the MPEG4 decoder 204 and decodes it to generate audio data. The SDRAM 210 is used in the above processing of the MPEG4 decoder 204.
[0015]
The LCD controller 207 drives the liquid crystal display panel 202 based on the video data supplied from the graphics controller 205. The D / A converter 208 receives the audio data output from the audio decoder 206, performs D / A conversion, generates a right (R) sound analog signal and a left (L) sound analog signal to generate the earphone 203. To give.
[0016]
Operation information for the touch panel 211 is given to the CPU 209 via the dedicated interface 212 and the system bus 213. The CPU 209 grasps the content of the command based on the correspondence between the operation information and the display of the operation button on the liquid crystal display panel 202 and executes necessary processing.
[0017]
The main body key 214 corresponds to the operation buttons (play / pause, stop, feed) related to viewing described above. Operation information for the main body key 214 is given to the CPU 209 via the interface 215 and the system bus 213. The CPU 209 executes necessary processing based on the operation information.
[0018]
In addition, a communication block 216 and an interface (for example, Bluetooth (trademark), etc.) 217 are provided to enable a wireless network. Further, a flash ROM 218 and an SDRAM 219 are also provided. The battery 221 is a secondary battery, and obtains power from a stationary peripheral device (not shown) and stores it. The mobile phone unit 231 is used for normal phone calls.
[0019]
The CPU 209 performs processing for a wireless network, data transmission / reception when the PHS data card 4 is installed in the slot 201, control of each functional unit based on received data, read / write control of the FlashROM 218 and SDRAM 219, and the like. ing.
[0020]
FIG. 3 is an explanatory diagram showing the relationship between the tuner 230 that receives terrestrial digital broadcasting and the mobile phone unit 231. The tuner 230 includes a tuner unit 230a for selecting a frequency and an OFDM demodulating unit 230b that demodulates the digital modulation signal having the selected frequency. The mobile phone unit 231 includes a high frequency unit 231a and a baseband unit 231b.
[0021]
The OFDM demodulator 230b includes a demodulator circuit, a deinterleave circuit, an error correction circuit, and the like, thereby demodulating the digital modulation signal output from the tuner unit 230a and outputting a transport stream. In the OFDM system, as shown in FIG. 4, in order to synchronize the symbol period, a period called a guard interval is provided between the symbol periods. Further, by providing this guard interval, the system is strong against multipath and fading, and is suitable for mobile reception. The guard interval can be detected by determining the correlation between the received signal and a signal obtained by delaying the received signal. Since the guard interval and the period of the effective symbol are fixed, by performing time measurement after detection, the tuner 230 can maintain synchronization even if the guard interval cannot be detected intermittently due to noise or the like. In addition, a signal indicating the guard interval can be output. The OFDM demodulator 230b has a notification output port, which outputs a signal such as High during the guard interval and Low during the symbol period. In addition, a notification input port is provided, and the notification input port receives notification (High, Low) from the baseband unit 231b.
[0022]
The baseband unit 231b executes protocol control for calling and protocol control for location registration. FIG. 5 shows a sequence for location registration. The baseband unit 231b has a notification input port. When receiving a High (indicating guard interval) signal from the OFDM demodulation unit 230b at this notification input port, the baseband unit 231b executes a sequence for position registration. The baseband unit 231b also has a notification output port. The notification output port outputs a signal such as “High” when a sequence for position registration is executed, and “Low” otherwise. This signal is given to the notification input port of the OFDM demodulator 230b.
[0023]
The OFDM demodulator 230b can recognize that the location registration processing is being performed in the mobile phone unit 231 by receiving a High (during location registration sequence) signal from the baseband unit 231b. Therefore, even if noise is detected in the guard interval, it can be determined that the noise is due to position registration processing, and the influence on OFDM demodulation can be reduced.
[0024]
FIG. 6 is a flowchart showing the processing contents of the mobile phone unit 231. The mobile phone unit 231 takes a state of receiving notification information from the base station (step S1). And it is judged whether the area changed based on this alerting | reporting information (step S2). If the area has changed, it is determined whether or not the transmission is permitted from the tuner 230 (step S3). That is, it is determined whether or not a high (guard interval) signal is received from the OFDM demodulator 230b at the notification input port. If it is during the guard interval (YES in step S3), the tuner 230 is notified that a radio wave for position registration is to be transmitted (step S4). Then, the location registration process is executed (step S5), and when the location registration process is completed, this is notified to the tuner 230 (step S6). When the portable viewing apparatus is powered on, the process proceeds to step S3.
[0025]
The guard interval is set to, for example, 1/4, 1/8, 1/16, or 1/32 (7.875 μs to 252 μs) of the effective symbol length, and there are cases where the entire position registration process cannot be completed during this period. it is conceivable that. In such a case, the baseband unit 231b performs the position registration process over a plurality of guard intervals. For example, in FIG. 4, when the channel activation parameter notification is received from the base station just before the end of the guard interval or during the symbol period, the location registration request is issued in the next guard interval after the symbol period. The process of sending out (performing radio wave transmission) is performed.
[0026]
【The invention's effect】
As described above, according to the present invention, position registration processing is performed in the mobile call means during the guard interval, and radio waves are not transmitted from the mobile call means during the effective symbol period, or effective. Since the time for transmitting radio waves within the symbol period is shortened, there is an effect that the reception trouble of terrestrial digital broadcasting is reduced.
[Brief description of the drawings]
FIG. 1 is an external perspective view showing a portable viewing device according to an embodiment of the present invention.
FIG. 2 is a block diagram of a portable viewing device according to an embodiment of the present invention.
FIG. 3 is an explanatory diagram showing a relationship between a tuner for receiving terrestrial digital broadcasting and a mobile phone unit in the portable viewing device according to the embodiment of the present invention;
FIG. 4 is an explanatory diagram showing a relationship between an effective symbol period and a guard interval in an OFDM modulated wave.
FIG. 5 is an explanatory diagram showing a location registration sequence in a mobile phone unit.
FIG. 6 is a flowchart showing a position registration process in the portable viewing device according to the embodiment of the present invention.
[Explanation of symbols]
2 Portable Viewing Device 202 Liquid Crystal Display Panel 204 MPEG4 Decoder 219 SDRAM
230 Terrestrial digital tuner 231 Mobile phone unit 3 Memory card 4 PHS data card

Claims (3)

In a portable viewing device comprising: broadcast receiving means for receiving terrestrial digital broadcast and outputting video and / or audio; and portable call means for making a call by transmitting and receiving radio waves. A portable viewing apparatus comprising: means for notifying the mobile call means of a guard interval, wherein the mobile call means is configured to execute a position registration process during the guard interval based on the notification. 2. The portable viewing device according to claim 1, wherein the portable call means is configured to notify the broadcast receiving means when performing a location registration process. apparatus. The portable viewing device according to claim 1 or 2, wherein when the time required for the position registration process is longer than the guard interval, the position registration process is performed over a plurality of guard intervals. A portable viewing device characterized by that.

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