JP2004120085A - Portable audio visual device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the broadcast receiving trouble due to sending of position registering radio waves by a mobile talking function of a portable audio visual device having a terrestial digital broadcast receiving function and the mobile talking function. <P>SOLUTION: The portable audio visual device 2 comprises a function for receiving a terrestial digital broadcast to output pictures and/or sounds (tuner 230, etc.), and a function for transmitting/receiving radio waves to talk (portable telephone 231). The tuner 230 gives the portable telephone 231 notice of a guard interval in OFDM-modluted signals. The portable telephone 231 executes a position registering process in the guard interval known by the notice. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
[Industrial applications]
The present invention relates to a portable viewing device capable of performing a telephone call by a mobile communication function in addition to a television viewing by terrestrial digital broadcasting.
[0002]
[Prior art]
In digital broadcasting using terrestrial waves, a transmission method called OFDM (Orthogonal Frequency Division Multiplexing) is used. In this OFDM transmission, a 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 for receiving the broadcast wave, in addition to a fixed installation apparatus fixedly installed in a house, it is assumed to be used as a mobile apparatus to which a reception function is added. For this reason, it has been considered to perform hierarchical transmission using a plurality of different transmission channel codings as well as broadcasting using a single transmission channel coding. In this layer transmission, a maximum of three layers are used, and there are a strong layer, a middle layer, and a weak layer in ascending order of the required C / N ratio. Then, a strong hierarchy broadcast is performed for portable devices.
[0003]
In recent years, mobile phones and PHS phones have become widespread, and it is conceivable to provide a portable viewing apparatus by mounting these mobile communication functions and terrestrial digital broadcast reception functions in a portable housing.
[0004]
As a conventional device, there is a device that performs telephone reception and program recording control when a telephone call is received while watching television broadcasting (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 their base stations of their positions, and therefore transmit radio waves even during a call. . Although this radio wave is different from the frequency of the television broadcast radio wave, the mobile communication function unit and the broadcast reception function unit exist close to each other, so that there is a possibility that the reception of the television broadcast may be hindered.
[0007]
In view of the above circumstances, it is an object of the present invention to provide a portable viewing device equipped with a terrestrial digital broadcast reception function and a mobile communication function, which reduces a broadcast reception obstacle caused by transmitting a location registration radio wave in a mobile phone function. .
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, a portable audio-visual apparatus according to the present invention is provided with a broadcast receiving means for receiving a terrestrial digital broadcast and outputting a video and / or a sound, and a portable communication means for performing a telephone call by transmitting and receiving radio waves. And a means for notifying a guard interval in the terrestrial digital broadcast to the portable communication means, and the portable communication means executes a position registration process during the guard interval based on the notification. It is characterized by having been constituted.
[0009]
With the above configuration, the location registration processing is performed during the guard interval, so that the reception trouble of the terrestrial digital broadcast is reduced. Even if the guard interval could not be detected due to noise caused by the transmission of radio waves due to the position registration process, the synchronization could be maintained for a predetermined period of time, so that the influence of the failure to detect the guard interval is small.
[0010]
Preferably, the portable communication means is configured to notify the broadcast receiving means when the location registration processing is being performed. 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 processing, and the influence on the demodulation processing of the terrestrial digital broadcast in the broadcast receiving means can be reduced.
[0011]
If the time required for the position registration processing is longer than the guard interval, the position registration processing is preferably performed over a plurality of guard intervals.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described below 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, projects the image on the liquid crystal display panel 202, and outputs the sound from the earphone. Also, it reads out encoded video / audio data from the memory card inserted into the slot 201, displays the video on the liquid crystal display panel 202, and outputs audio from the earphone. A touch panel 211 is attached on the liquid crystal display panel 202, and a desired instruction can be given by performing a panel operation with a touch pen or the like. Note that operation buttons (play / pause, stop, forward, volume, etc.) related to viewing are provided on the housing.
[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 as a built-in memory is supplied to the MPEG4 decoder 204 via the system bus 213. Then, the tuner 230 that receives the terrestrial digital broadcast extracts the MPEG4 bit stream data broadcasted by the terrestrial digital broadcast and supplies it to the MPEG4 decoder 204, or the system bus for recording on 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 transform, 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 a process of displaying, on the liquid crystal display panel 202, characters and the like (operation buttons, a menu screen, an EPG screen based on program information obtained from terrestrial digital broadcasting, etc.) output from the CPU 209. The audio decoder 206 receives the audio code data in the bit stream from the MPEG4 decoder 204 and decodes the audio code data 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, and generates the earphone 203. Give to.
[0016]
Operation information for the touch panel 211 is provided to the CPU 209 via the dedicated interface 212 and the system bus 213. The CPU 209 grasps the contents of the command based on the correspondence between the operation information and the display of the operation buttons and the like 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, forward) related to viewing described above. Operation information for the main body key 214 is provided to the CPU 209 via the interface 215 and the system bus 213. The CPU 209 performs necessary processing based on the operation information.
[0018]
Further, a communication block 216 and an interface (for example, Bluetooth (trademark) 217) are provided to enable a wireless network. Further, a flash ROM 218 and an SDRAM 219 are provided. The battery 221 is a secondary battery, which receives power from a stationary peripheral device (not shown) and stores the power. The mobile phone unit 231 is used for a normal telephone.
[0019]
The CPU 209 performs processing for a wireless network, data transmission / reception when the PHS data card 4 is inserted into the slot 201, control of each functional unit based on received data, read / write control of the FlashROM 218 and the SDRAM 219, and the like. ing.
[0020]
FIG. 3 is an explanatory diagram showing the relationship between the tuner 230 for receiving terrestrial digital broadcasting and the mobile phone unit 231. The tuner 230 includes a tuner 230a for frequency selection and an OFDM demodulator 230b for demodulating a digitally modulated signal of the selected frequency. The mobile phone unit 231 includes a high-frequency unit 231a and a baseband unit 231b.
[0021]
The OFDM demodulation unit 230b includes a demodulation circuit, a deinterleave circuit, an error correction circuit, and the like, and demodulates a digital modulation signal output from the tuner unit 230a to output a transport stream. In the OFDM system, as shown in FIG. 4, a period called a guard interval is provided between symbol periods in order to synchronize symbol periods. In addition, by providing this guard interval, a system that is resistant to multipath, fading, etc. becomes suitable for mobile reception. The guard interval can be detected by judging the correlation between the received signal and the delayed signal. Since the guard interval and the period of the effective symbol are fixed, by measuring the time after the detection, the tuner 230 can maintain synchronization even if the guard interval cannot be intermittently detected due to noise or the like. And a signal indicating that the guard interval is in progress can be output. The OFDM demodulation section 230b has a notification output port, and outputs a signal at this notification output port as High during a guard interval and as Low during a symbol period. In addition, it has a notification input port, and receives a notification (High, Low) from the baseband unit 231b at this notification input port.
[0022]
The baseband unit 231b executes a protocol control for a call and a protocol control for a location registration. FIG. 5 shows a sequence for location registration. The baseband unit 231b has a notification input port, and when receiving a High (indicating a guard interval) signal from the OFDM demodulation unit 230b at this notification input port, executes a sequence for position registration. The baseband unit 231b has a notification output port, and outputs a signal at the notification output port, such as High when a sequence for location registration is executed, and Low at other times. This signal is provided to the notification input port of the OFDM demodulation section 230b.
[0023]
The OFDM demodulation unit 230b can recognize that the location registration processing is being performed in the mobile phone unit 231 by receiving a High (during the 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 the 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 the notification information from the base station (step S1). Then, it is determined whether or not the area has changed based on the notification information (step S2). If the area has changed, it is determined whether there is a transmission permission from the tuner 230 (step S3). That is, it is determined whether or not a High (guard interval) signal is received from the OFDM demodulation unit 230b at the notification input port. If it is during the guard interval (YES in step S3), it notifies the tuner 230 that a radio wave for position registration is to be transmitted (step S4). Then, a position registration process is executed (step S5), and when the position registration process ends, the fact is notified to the tuner 230 (step S6). When the power of the portable viewing device is turned 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 during this period, it may not be possible to complete all of the location registration processing. 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 notification of the channel activation parameter is received from the base station immediately before the end of the guard interval or during the symbol period, a position registration request is issued in the next guard interval after the symbol period. That is, a process of sending out (transmitting a radio wave) is performed.
[0026]
【The invention's effect】
As described above, according to the present invention, the location registration processing in the mobile communication means is performed during the guard interval, and no radio wave is transmitted from the mobile communication means during the effective symbol period, or Since the time for transmitting the radio wave within the symbol period is shortened, there is an effect that the reception trouble of the 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 the portable viewing device according to the 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 of 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 the mobile phone unit.
FIG. 6 is a flowchart showing a position registration process in the portable viewing device of 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 / listening apparatus comprising: broadcast receiving means for receiving a terrestrial digital broadcast and outputting video and / or audio; and portable communication means for making a call by transmitting and receiving radio waves, A portable viewing device, comprising: means for notifying a guard interval to the mobile communication means, wherein the mobile communication means is configured to execute a position registration process during a guard interval based on the notification. 2. The portable viewing / listening device according to claim 1, wherein the portable communication unit is configured to notify the broadcast reception unit of the location registration process when the location registration process is being performed. apparatus. The portable viewing device according to claim 1 or 2, wherein when the time required for the position registration processing is longer than the guard interval, the position registration processing is performed over a plurality of guard intervals. A portable viewing device characterized by the above-mentioned.

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