JP4271254B2 - Digital broadcast receiver - Google Patents

Description

  The present invention relates to a digital broadcast receiver, and more particularly to a stationary receiver and a mobile digital broadcast receiver built in a portable terminal such as an in-vehicle terminal, a mobile phone, or a PDA (Personal Digital Assistant).

  Currently, preparations for digital terrestrial broadcasting are being promoted as a new alternative to analog terrestrial broadcasting being watched nationwide. Terrestrial digital broadcasting will start in 2003 in the three major metropolitan areas of Kanto, Kinki, and Tokai. In 2006, the broadcasting area will be expanded nationwide. Accordingly, the current analog broadcasting is scheduled to be abolished in 2011.

  In the terrestrial digital broadcast technical standard ISDB (Integrated Services Digital Broadcasting) -T, an OFDM (Orthogonal Frequency Division Multiplexing) system using a large number of carriers is adopted as a modulation system. The OFDM scheme can suppress ghost interference caused by the formation of a plurality of propagation paths (multipaths) due to reflection in a building or the like. In ISDB-T, a transmission mode that defines the carrier interval, a modulation method for each carrier, and a plurality of guard intervals in the time axis direction that are provided for each effective symbol length are defined, and a very large number of signal formats conform to the standard. Is allowed. Actually, an optimum signal format is selected from a large number of signal formats according to a service mode such as fixed reception or mobile reception.

  In ISDB-T, one channel (bandwidth of about 5.6 MHz) can be divided into 13 segments (1 segment = about 430 kHz), and the modulation method can be changed in units of segments. Thus, the broadcasting station can arbitrarily determine the signal configuration on one channel, such as audio broadcasting and high-vision broadcasting, or standard fixed broadcasting and mobile broadcasting.

  Furthermore, since ISDB-T incorporates interleaving in the time axis direction and radio waves to be used are suitable for transmission to mobile objects, mobile receivers such as in-vehicle TVs and portable terminals such as PDAs and mobile phones. One of the major features is that stable reception is possible. In the future, a service that assumes such mobile reception is also highly expected.

  Mobile receivers such as in-vehicle TVs can be equipped with a display with a large display capacity to some extent and are equipped with a sufficient power supply source, so the demands for small size and light weight and low power consumption are not so great. Therefore, it is possible to cope with wide band reception. FIG. 9 is a diagram illustrating a configuration example of a data segment used for the digital terrestrial broadcasting service. As shown in FIG. 9, the data segment 801 includes a one-segment audio reception band 803, a six-segment mobile reception band 804, and a six-segment SDTV (Standard Definition TV, standard television) reception band 805. A total of 13 segments are allocated. In the in-vehicle television as described above, a sufficient amount of information can be obtained from the broadcasting service using the data segment. The data segment 801 is converted into a transmission spectrum (OFDM segment) 802 on the frequency axis. At this time, the 1-segment reception portion 806 (A layer) corresponding to the voice reception 803 is a central segment of 13 segments. Placed in.

  FIG. 10 is a diagram illustrating a configuration example of another data segment of the terrestrial digital broadcasting service. As shown in FIG. 10, 13 segments including a mobile reception band 903 for one segment and a high-definition TV reception band 904 for 12 segments are allocated to the data segment 901. Similar to the form shown in FIG. 8, the data segment 901 is converted into a transmission spectrum (OFDM segment) 902 on the frequency axis. At this time, a portion 905 (A layer of the 1-segment reception band corresponding to the mobile reception band 903 is used. ) Is arranged in the center segment of the 13 segments.

In the configuration shown in FIG. 10, in the data segment 901, all 12 segments other than the mobile reception band 903 are allocated to the high-definition TV reception 904. Various forms of broadcasting services are considered.

  As described above, terrestrial digital broadcasting adopts a method suitable for mobile reception and mobile reception, and is generally affected by various radio wave interferences in the radio wave transmission path, causing noise, screen loss, synchronization Compared to analog TV broadcasting, where abnormalities are likely to occur, stable reception is possible without being affected by environmental changes due to movement or the like.

  However, even in terrestrial digital broadcasting, depending on the reception environment, there may be cases where the reception power of radio waves is weak, noise is significantly superimposed, etc., and in particular, the influence of fading that the intensity of the received signal changes with time. In large environments, it may not be possible to reproduce good video.

  In order to cope with such deterioration of the reception environment, a method of detecting the reception state in the reception apparatus and automatically switching the broadcast content in accordance with this is adopted. (For example, the digital broadcast receiver described in Patent Documents 1 to 3.)

JP-A-9-107303 JP 2002-176594 A JP 2002-218341 A

  When receiving digital broadcasts, there is a particular problem in that there is no intermediate reception situation such as “appropriately visible” or “difficult to see to some extent” as with analog broadcasts in digital broadcast receivers. Essentially, there is only one of the reception enabled state and the reception disabled state, that is, there is a clear threshold regarding whether or not reception is possible. In the case of analog broadcasting, it is easy for the viewer to check the intermediate state of the reception status, so if the video is disturbed, adjust the antenna direction or change the position of the receiving device while looking at the screen It is also possible to search for an environment suitable for reception on the spot.

  However, in the case of digital broadcasting, when the viewer is unable to receive the broadcast, how much the current reception environment is suitable for broadcast reception or what kind of environment, depending on the digital reception and display characteristics as described above. For example, it is difficult to determine whether or not it is in an unsuitable state for receiving broadcasts, and therefore, for example, it is difficult to determine in which direction the place can be received.

  An object of the present invention is to provide a digital broadcast receiving apparatus that can obtain more detailed information regarding the current reception status at least when a digital broadcast cannot be received.

  Note that the present invention is not limited to terrestrial digital broadcasting, but covers all general digital broadcasting. In particular, a great effect is expected for broadcasting for mobiles and portable terminals. For example, 2.6 GHz satellite digital audio broadcasting (mobile broadcasting) scheduled to start in Japan in 2004 is targeted.

  The present invention has a reception sensitivity parameter detection means for detecting a reception sensitivity parameter of digital broadcasting, and a reception status display means for displaying a reception status based on the reception sensitivity parameter detected by the reception sensitivity parameter detection means. The reception status display means displays a message when the digital broadcast cannot be received. The reception status display means preferably displays the reception status parameters so as to change using a time axis. Furthermore, it is preferable to have a location information acquisition unit that acquires location information, and the reception status display unit displays the parameter of the reception status in association with the location information. It is preferable that the reception status display means switches between a received video display and a parameter display of the reception status. It is preferable that the reception status display means displays a factor that the digital broadcast cannot be received.

  Further, the present invention is a digital broadcast receiving apparatus having means for detecting a reception sensitivity parameter of a digital broadcast and means for displaying a reception status based on the reception sensitivity parameter, and at least when the digital broadcast cannot be received, It is an object of the present invention to provide a digital broadcast receiving apparatus that displays the reception status.

  As a result, the viewer can grasp the reception status under the current reception environment, and can determine whether reception is possible by environment adjustment and search for an environment suitable for reception. In the present invention, the reception sensitivity parameter preferably includes at least one of reception power and C / N ratio.

  The reception sensitivity information may include reception power, C / N ratio, and total sensitivity calculated from the reception power and C / N ratio. In this case, the total sensitivity can be calculated using only the lower sensitivity value of the received power and C / N ratio as a parameter.

  Further, the digital broadcast receiving apparatus has means for detecting a BER, and the reception status based on the reception sensitivity parameter can be displayed using the BER as a criterion.

  As parameters for judging the reception status in digital broadcasting, reception power and C / N ratio (Carrier to Noise Rate) are generally known. These values have different lower limit values required for reception depending on the modulation method and coding rate.

Further, in order to transmit a video signal without error (pseudo error free) in digital broadcasting, the value of BER (Bit Error Rate) of RS (Reed Solomon) code decoding output needs to be 1 × 10 ⁻¹¹ or less. There is. For this purpose, the BER value of the Viterbi decoding output needs to be 2 × 10 ⁻⁴ .

  For example, in a Gaussian noise environment, the required C / N ratio in the case of QPSK coding rate 1/2 is 4.9 dB, and the required C / N ratio in the case of 16 QAM coding rate 1/2 is 11.5 dB. is there. As for the required electric field strength of the received power, about 60 dBμV / m is required in the case of fixed reception.

  According to the present invention, it is possible to infer the factors that cannot be received by monitoring the values of the respective parameters. For example, if the received power is sufficient while moving by car but the C / N ratio is low, it is highly possible to receive by reducing the speed, and if the received power is low in the city, Alternatively, it is possible to obtain a policy of moving to a place where a reflected wave or a standing wave can be received even when there is a shield.

  In the present invention, the digital broadcast receiving apparatus further includes means for detecting or inputting position information from the outside, and displays a reception status based on the position information and the reception sensitivity parameter. To do.

  As a result, it is possible to first determine whether or not a receiving device that attempts to receive is located in the broadcast service area. If it is outside the service area, it is displayed that direct reception is impossible, and if it is within the service area, the reception status based on the reception sensitivity parameter can be displayed.

  At this time, if the digital broadcast receiving apparatus has receivable broadcast station list data corresponding to the position, the reception status display can be easily performed. Note that the broadcast station list data corresponding to the position does not necessarily have to be held internally as fixed data by the receiving device, and it is also possible to obtain the latest information from the distribution destination using a communication line.

  In the digital broadcast receiving apparatus of the present invention, when the reception sensitivity parameter falls below a value necessary for broadcast reception, the reception status can be automatically displayed. At this time, as the reception status, comments such as “out of service area”, “not receiving radio waves”, “cannot be received due to noise” may be displayed.

  In addition, the digital broadcast receiving apparatus of the present invention can include a display unit that displays the reception status independently of the display screen. As a result, video and reception status can be displayed simultaneously, and it is possible not only to check the reception status while watching the video, but also to easily check only the reception status without displaying the main screen. Become.

  The digital broadcast receiving apparatus of the present invention is preferably incorporated in, for example, a mobile phone terminal, a vehicle-mounted terminal, a stationary digital broadcast receiver, a portable information communication terminal (such as a PDA).

  Further, it may be a digital broadcast receiver capable of receiving terrestrial digital broadcasts and mobile broadcasts using satellites.

  According to the digital broadcast receiving apparatus of the present invention, the viewer can grasp the reception sensitivity information under the current reception environment, and how far the reference value becomes acceptable when the reception environment is bad. It is possible to know whether it is in the situation, and what can not be received due to the factor.

  The digital broadcast receiving apparatus according to the present invention, in particular, should be moved in any direction with respect to a viewer who receives a digital broadcast at a mobile terminal and moves to find a place where the broadcast can be received. It is a device that can provide information as a guideline for such a determination. Fixed digital broadcast receivers, especially stationary TV devices equipped with antennas, are installed in an indoor location and cannot be received. In some cases, it is a device that can present information about its location.

  Hereinafter, a digital broadcast receiving apparatus according to an embodiment of the present invention will be described with reference to the drawings. In the following, a terrestrial digital broadcast receiver will be described as an example of a digital broadcast receiver. However, these techniques are also applied to other digital broadcast receivers such as satellite digital broadcast receivers. Is possible.

  First, the digital broadcast receiver according to the first embodiment of the present invention will be described by taking a terrestrial digital broadcast receiver built in a mobile phone terminal as an example. FIG. 1 is a functional block diagram showing a configuration example of a terrestrial digital broadcast receiving apparatus according to the present embodiment. As shown in FIG. 1, a mobile terminal 100 equipped with a terrestrial digital broadcast receiver according to the present embodiment includes a first antenna 101, a tuner 102, an OFDM demodulator 103, a decoder unit 104, and a main storage unit. 106, a memory 107, a control unit 109, a second antenna 110, a w-CDMA processing unit 112, an audio signal processing unit 115, and a video signal processing unit 118. Furthermore, the terrestrial digital broadcast receiving apparatus 100 includes a secondary storage medium 105, a timer 108, a microphone 116, a speaker 117, and a display 119. The w-CDMA processing unit 112 includes a baseband processing unit 113 and a telephone voice processing unit (AD / DA) 114.

  The operation of the mobile terminal 100 provided with the above terrestrial digital broadcast receiver will be described. The terrestrial digital broadcast signal received by the first antenna 101 is restored to an audio signal and a video signal via the tuner 102, the OFDM demodulator 103, and the decoder unit 104, and the audio signal passes through the audio signal processing unit 115. The video signal is reproduced by the speaker 117, and the video signal is input to the video signal processing unit 118 and displayed on the display 119.

  In addition, the cellular phone communication signal received from the second antenna 110 is output from the speaker 117 through the RF processing unit 111 and the w-CDMA processing unit 112 including the baseband processing unit 113 and the telephone voice processing unit 114. The On the contrary, the voice input from the microphone 116 is transmitted from the second antenna 110 through the w-CDMA processing unit 112 and the RF processing unit 111.

  When the mobile phone terminal 100 is connected to the Internet through a mobile phone communication signal, communication information included in the mobile phone communication signal is transmitted from the baseband processing unit 113 to the display unit 119 via the decoder unit 104 and the video signal processing unit 118. Is displayed. The control unit 109 controls each component of the mobile phone terminal 100. The other constituent elements are the same as those of a general terrestrial digital broadcast receiving apparatus.

  FIG. 2 is a functional block diagram showing an example of the internal configuration of the OFDM demodulator 103 of the mobile phone terminal 100 shown in FIG. As shown in FIG. 2, the OFDM demodulator 103 includes an orthogonal demodulation unit 201, a phase correction unit 202, an FFT unit 203, a frame synchronization unit 204, a detection unit 205, a frequency / time deinterleaving unit 206, A bit deinterleaving unit 207, a Viterbi decoding unit 208, a byte deinterleaving unit 209, an energy spreading unit 210, a TS reproduction unit 211, and an RS decoding unit 212 are provided.

  A broadcast signal converted into an IF (intermediate frequency) signal by the tuner 102 of the mobile phone terminal 100 shown in FIG. The broadcast signal input to the quadrature demodulation unit 201 is input to the detection unit 205 via the phase correction unit 202, the FFT unit 203, and the frame synchronization unit 204. The detection unit 205 detects a parameter related to the C / N (Carrier to Noise) ratio of the broadcast signal, and outputs the detected C / N signal via the C / N output unit 213.

  On the other hand, a TS (Transport Stream) signal output from the detector 205 includes a frequency / time deinterleaver 206, a bit deinterleaver 207, a Viterbi decoder 208, a byte deinterleaver 209, an energy spreader 210, and a TS reproducer. 211, an RS (Reed-Solomon) decoding unit 212, a parameter relating to BER (Bit Error Rate) is output to the control unit 109 of the mobile phone terminal shown in FIG. Is output to the decoder unit 104 (FIG. 1) via the TS output unit 215.

  Note that it is also possible to set the RS decoding to be turned on and the TS to be outputted when the BER value satisfies a certain reference value with the RS decoding turned off.

  As will be described later, when the received video and the reception sensitivity are displayed at the same time, the C / N ratio and the BER after RS (Reed-Solomon) decoding are detected, and the TS is always sent to the decoder unit 104. It is also possible. The received power can be determined from the value of AGC (Auto Gain Control) that controls the output IF from the tuner arranged upstream of the orthogonal demodulator 201.

  Note that the components in the OFDM demodulator 103 shown in FIG. 2 are the same as those included in a general OFDM demodulator, and a description of each component is omitted.

  Next, a technique for displaying received digital broadcast and reception sensitivity information in the digital broadcast receiving apparatus according to the present embodiment configured as described above will be described. FIG. 3 is a diagram showing a configuration example of a display screen of a mobile phone terminal incorporating the digital broadcast receiving device according to the present embodiment. FIG. 3A is a display example of the menu screen of the mobile phone terminal. The display screen shown in FIG. 3A displays a first display unit 301 that displays the remaining battery level, communication sensitivity, and the like, and a second display unit 302 that displays menu selection items. Menu selection items displayed on the second display unit 302 include TV, web, mail, address book, and schedule items.

  Hereinafter, a display example of the mobile phone terminal will be described when the TV is selected on the display unit 302, that is, when the reception of the terrestrial digital broadcast is selected using the digital broadcast receiving apparatus according to the present embodiment. To do. The other menu selection items described above are the same as the functions included in a general mobile phone terminal, and thus the description thereof is omitted in this specification.

  When a TV is selected and a TV channel is selected on the menu screen shown in FIG. 3A, a communication / broadcast display screen shown in FIG. 3B is displayed. The communication / broadcast display screen includes a first display unit 301, and a broadcast display unit 303 and a communication display unit 304 corresponding to the second display unit 302 in FIG. The broadcast display unit 303 displays the received digital terrestrial broadcast content itself, and the communication display unit 304 displays content-related information and data broadcasts transmitted along with the content. The content related information can be displayed by selecting related information such as personal data of the A player, the result of other stadiums, and the Hawks homepage.

  When “sensitivity” is selected in the communication display unit 304, a broadcast / reception sensitivity display screen shown in FIG. 3C is displayed. The reception sensitivity display screen 305 displays broadcast reception sensitivity in a bar graph shape. In the display example according to the present embodiment, for example, the reception sensitivity 100 is set as a reference value capable of normally receiving a broadcast. It should be noted that as to which of reception power and C / N ratio is selected as the reception sensitivity, the one having a lower value is selected, and even if the lower value is selected, a necessary reference value (this value is set to 100). It is preferable that it is determined that the broadcast is normally received when the above condition is satisfied.

  In the mobile phone terminal according to the present embodiment, when the broadcast cannot be normally received because the broadcast reception sensitivity is lower than a predetermined value, for example, when reception is impossible as shown in FIGS. 3 (d) to 3 (f). One of the display screens is displayed. In the broadcast display section 303 when reception is impossible, position information and reception sensitivity parameters are displayed instead of broadcast content. In FIG. 3D, a message “out of service area” and a bar graph relating to reception sensitivity are displayed as the first display screen when reception is impossible. In FIG. 3E, a message “Cannot be received due to noise” and a C / N bar graph are displayed as a second display screen when reception is impossible. As for C / N, a value of about 70, which is lower than the reference value 100, is displayed. In FIG. 3F, a message “The radio wave is weak and cannot be received” and a bar graph of received power are displayed as a third display screen when reception is impossible. As for the received power, a value of about 70, which is lower than the reference value 100, is displayed. In this way, a message such as “out of service area” is displayed based on the position information and the reception sensitivity parameter.

  Since the digital broadcast receiving apparatus according to the present embodiment is built in the mobile phone terminal, the broadcast reception sensitivity changes sequentially as the viewer moves. Therefore, the display screen of FIG. 3 (b) or FIG. 3 (c) that normally receives the broadcast and the display screen of FIG. 3 (d) to FIG. It is preferable to switch automatically according to the above.

  In the digital broadcast receiving apparatus according to the present embodiment, since the broadcast display unit 303 and the reception sensitivity display unit 305 are displayed in different areas, when the reception environment is bad, the reception sensitivity display unit 305 monitors the change in reception sensitivity. However, there is also an advantage that the direction of the antenna and the reception position can be adjusted.

  FIG. 4 is a flowchart showing an operation flow from the viewer selecting digital broadcast reception until the video display is performed and a display screen switching operation due to a change in reception sensitivity in the above mobile phone terminal. It is. In the following description, it is assumed that the operation on the mobile phone terminal side is controlled by the control unit 109 shown in FIG.

  First, the viewer selects TV as a selection button for receiving TV on the menu screen shown in FIG. 3A (step 401), and then selects a reception channel, a display form, and the like (step 402). . If the mobile phone terminal has a location information detection function such as GPS, or if the reception position is registered in the terminal in advance, the presence / absence of broadcasting related to the selected channel, that is, the reception position is within the service area Whether or not (step 403). If the reception position is outside the service area in step 403, a message to that effect is displayed (step 404). If within the service area, the cellular phone terminal detects reception sensitivity information (described later) obtained from the tuner 102 (FIG. 1) and the OFDM demodulator 103 (FIG. 1) (step 405). The mobile phone terminal further determines, based on the reception sensitivity information, whether or not the current reception sensitivity satisfies a predetermined reference value necessary for receiving the broadcast of the channel selected above (step 406). ) If the standard is satisfied, the video is displayed (step 407).

  When the current reception sensitivity, for example, the reception power and the C / N ratio do not satisfy a predetermined reference value, or when either value does not reach the reference value (steps 408 and 410) 3 (d) to FIG. 3 (f), a message indicating that reception is not possible is displayed according to the display screen example when reception is impossible (steps 409, 411, and 412), and reception sensitivity information is displayed. Is displayed. While viewing the reception sensitivity information, the viewer can search for the antenna direction and reception position suitable for broadcast reception, and obtain a more suitable position.

  Next, a method for measuring reception sensitivity in the digital broadcast receiving apparatus according to the present embodiment will be described. An example in which the received power and the C / N ratio of the received signal are used as the reception sensitivity parameter will be described. In FIG. 1, the tuner 102 detects the received power, detects the C / N ratio of the received signal in the OFDM demodulator 103 (in the C / N ratio output unit 213 shown in FIG. 2), and outputs each to the control unit 109. It is configured as follows. The OFDM demodulator 103 is configured to output the BER of the received signal from the BER output unit 214 in FIG. 2 to the control unit 109 in FIG.

  The control unit 109 shown in FIG. 1 calculates reception sensitivity information by comparing information such as the input C / N ratio and BER with a predetermined reference, and outputs the received sensitivity information to the display 119 through the video signal processing unit 118. Here, various embodiments can be considered for the reference for calculating the reception sensitivity information. For example, for each parameter of the reception power and C / N ratio, the reception reference value corresponding to each modulation method used for broadcasting is set to 100%, and the value is also in a reasonable range according to the general fluctuation range. It is also possible to obtain a conversion value so as to change at and to display this as a parameter. In this way, it is possible to avoid a situation in which a specific guideline for improving the reception situation cannot be obtained because each parameter can display substantially only two values.

When the reception sensitivity information is calculated by comprehensively evaluating each parameter of the received power and the C / N ratio, for example, a BER value after Viterbi decoding is detected, and this value becomes a pseudo error free threshold BER = The reception state when 2 × 10 ⁻⁴ can be used as a reference with a reception sensitivity of 100%. As described above, when the BER value is not used, a calculation formula derived in advance for the C / N ratio and the reception power (for example, a calculation formula for weighting the C / N ratio and the reception power). Can be applied to calculate the reception sensitivity. Alternatively, as a simpler method, one having a worse condition among the C / N ratio and the reception power may be selected, and the value may be used as reception sensitivity information.

  Next, a modification of the display form in the digital broadcast receiving apparatus according to the above embodiment will be described with reference to the drawings. FIG. 5A to FIG. 5D are diagrams showing a display form of reception sensitivity information different from the form shown in FIG. The display examples shown in FIG. 5 are displayed almost on the entire display screen of the mobile phone terminal. For example, the communication / broadcast display screen in FIG. 3B and the broadcast / reception sensitivity display screen in FIG. When the user is displayed, the display screen can be switched to each display example shown in FIG. 5 by the user's operation or automatically based on the reception sensitivity or the like.

  In display example 1 shown in FIG. 5A, the C / N ratio (C / N), the received power (Power), and the reception sensitivity (Total) obtained by comprehensively evaluating them are displayed in a bar graph form. Further, in display example 2 shown in FIG. 5B, only the comprehensively evaluated reception sensitivity is displayed in a bar graph shape. According to these display forms, the viewer can grasp the parameter indicating the current reception state based on a display that continuously changes to some extent, and based on these displays, the position of the antenna of the mobile phone terminal It is possible to search for a more preferable reception environment by changing the reception position and the like.

  In display example 3 shown in FIG. 5C, the received power and the C / N ratio are two-dimensionally mapped and displayed. The vertical axis represents received power (power), and the horizontal axis represents C / N (ratio). In FIG. 5 (c), point 502 indicates the current reception status. A hatched area indicates a receivable area. Based on the display shown in FIG. 5C, the viewer can search for a better reception environment based on the two-dimensional information with respect to the reception power and the C / N ratio.

  In display example 4 shown in FIG. 5D, the reception sensitivity up to the present is displayed along the time axis. According to this, when the reception sensitivity is time-dependent even at the same reception position, or when the reception sensitivity changes due to weather conditions or various environmental conditions, it is possible to know the pattern of change in reception sensitivity, Guidelines for obtaining a better reception environment can be obtained.

  As mentioned above, the display example of the reception sensitivity information in the digital broadcast receiving apparatus of the present embodiment has been shown. Various patterns are possible.

  6A and 6B show other display examples. The display examples shown in FIGS. 6A and 6B may be displayed on the display screen at the same time, or may be configured to be switched and displayed by a changeover switch or the like. FIG. 6A shows a state where a map 1001 is displayed on the display screen. On the map 1001, a trajectory 1003 in which the mobile phone terminal has moved is displayed. For example, it is displayed that the mobile phone terminal exists at positions P1 to P5 at predetermined time intervals. In FIG. 10B, the received power and the C / N ratio at each position from P1 to P5 are displayed as numerical values. Note that the position information, received power, and C / N ratio can be stored in a memory. The position information and the reception information are acquired in association with each other at a fixed time and stored in the memory. Information for estimating in which direction the viewer moves in relation to the current position P5 by referring to the display as shown in FIGS. 6 (A) and 6 (B). Can be obtained.

  As described above, according to the digital broadcast receiving apparatus according to the present embodiment, when the reception environment deteriorates, the viewer is in a state suitable for broadcast reception based on the reception sensitivity information displayed on the screen. It is possible to search. In addition, when the received broadcast suddenly stops being displayed, the viewer can be informed that the cause is due to the reception status, and the viewer can be given a certain level of security.

  Next, a digital broadcast receiver according to a second embodiment of the present invention will be described with reference to the drawings. In the present embodiment, a stationary terrestrial digital broadcast receiver mainly used indoors is targeted. The digital broadcast receiving apparatus according to the present embodiment is characterized in the form of a display screen, but the other configurations and operations are substantially the same as those of the digital broadcast receiving apparatus according to the first embodiment. .

  FIG. 7 is a diagram showing a configuration example of a display screen of the digital broadcast receiving apparatus according to the present embodiment. The digital broadcast receiving apparatus according to the present embodiment includes a video display unit 601, an antenna 602, and a speaker 603, and the main internal configuration is almost the same as the configuration shown in FIGS. is there. In FIG. 7, when the broadcast reception shown in FIG. 7A is possible, the received video is displayed on the screen. When the broadcast reception shown in FIG. 7B is impossible, reception sensitivity information is displayed on the screen. The reception sensitivity information shown in FIG. 7B shows a display example according to the display example 1 of FIG. 5A, but the display examples 2 to 5D of the other FIG. The display form according to the display example 4 may be used, or other display forms may be used. Further, switching between the screen shown in FIG. 7A and the screen shown in FIG. 7B may be automatically switched depending on the reception sensitivity, or may be switched by the operation of the viewer.

  When the digital broadcast receiving apparatus according to the present embodiment is used, it is possible to search for an installation position suitable for reception based on reception sensitivity information when deciding where to place the receiving apparatus indoors. . For example, if it is found that the received power is sufficient but the C / N ratio is low, install it in a place away from home appliances that are likely to cause noise, or in a place where there is no obstruction around it. If it is found that the received power is low, the installation position can be moved to a window, a place where a reflected wave or a standing wave can be received. In addition, when the received broadcast suddenly stops being displayed, the viewer can be informed that the cause is due to the reception status, and the viewer can be given a certain level of security.

  Next, a digital broadcast receiving apparatus according to a third embodiment of the present invention will be described with reference to the drawings. The digital broadcast receiver according to this embodiment is a terrestrial digital broadcast receiver built in a portable information communication terminal (PDA or the like). The digital broadcast receiving apparatus according to the present embodiment is characterized in the form of a display screen, but the other configurations and operations are substantially the same as those of the digital broadcast receiving apparatus according to the first embodiment.

  FIG. 8 is a diagram illustrating a configuration example of a display screen of the digital broadcast receiving apparatus according to the present embodiment. The digital broadcast receiving apparatus according to the present embodiment includes a broadcast display unit 701, a communication display unit 702, a reception sensitivity display bar 703, and an operation unit 704. The internal configuration is shown in FIGS. This is the same as the apparatus shown in FIG.

  In this embodiment as well, as in the first embodiment, when the reception environment deteriorates, the viewer is in a state suitable for broadcast reception based on the reception sensitivity information displayed on the screen. It is possible to search.

  Furthermore, for example, the broadcast station list data shown in Table 1 may be displayed by operating the operation unit 704. As shown in Table 1, the broadcast station list data can display the service area as range information for each broadcast station. By comparing this with current position information, it is possible to obtain information such as which broadcast station is currently receivable and which broadcast station is receivable at which position. In other embodiments, the same display can be performed. In Table 1, the range information of the service area of the broadcasting station is rectangular for convenience of description, but in general, it is often within a range defined by a circle.

  As described above, according to the digital broadcast receiving apparatus according to each embodiment of the present invention, the viewer can grasp the reception sensitivity information under the current reception environment, and the reception environment is poor. Thus, it is possible to know how far the standard value that can be received is deviated, and what is the reason why the reception is impossible.

  As mentioned above, although each embodiment of the digital broadcast receiver of this invention was described, this invention is not limited to these, In the range which does not deviate from the summary of this invention, it is possible to add various changes. It is.

It is a functional block diagram which shows the structure of the mobile telephone terminal incorporating the digital broadcast receiver by the 1st Embodiment of this invention. FIG. 2 is a functional block diagram showing an internal configuration of an OFDM demodulator of the mobile phone terminal shown in FIG. 1. It is a figure which shows the structural example of the display screen of the mobile telephone terminal shown in FIG. FIG. 3 is a flowchart showing the flow of operations from when a viewer selects reception of digital broadcast until video display is performed, and switching operation of a display screen due to a change in reception sensitivity in the mobile phone terminal shown in FIG. is there. It is a figure which shows the other display form (modification) of receiving sensitivity information on the display screen of the mobile telephone terminal shown in FIG. FIG. 6A is an example of a reception status display screen in the digital broadcast receiving apparatus according to the embodiment of the present invention, and FIG. 6A is a diagram illustrating an example of a display screen in which a trajectory that a viewer has moved is displayed on a map. FIG. 6B is a display example of received information at a plurality of points. It is a figure which shows the structural example of the display screen of the stationary receiving apparatus incorporating the digital broadcast receiver by the 2nd Embodiment of this invention. It is a figure which shows the structural example of the display screen of the portable information communication terminal incorporating the digital broadcast receiver by the 3rd Embodiment of this invention. It is a block diagram which shows one form of a terrestrial digital broadcasting service. It is a block diagram which shows the other form of a terrestrial digital broadcasting service.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 ... Antenna, 102 ... Tuner, 103 ... OFDM demodulator, 104 ... Decoder part, 105 ... Secondary storage medium, 106 ... Main storage part, 107 ... Memory, 108 ... Timer, 109 ... Control part, 110 ... Antenna, 111 ... RF processing unit, 112 ... w-CDMA processing unit, 113 ... baseband processing unit, 114 ... telephone audio processing unit, 115 ... audio signal processing unit, 116 ... microphone, 117 ... speaker, 118 ... video signal processing unit, 119 DESCRIPTION OF SYMBOLS ... Display, 201 ... Quadrature demodulation unit, 202 ... Phase correction unit, 203 ... FFT unit, 204 ... Frame synchronization unit, 205 ... Detection unit, 206 ... Frequency / time deinterleaving unit, 207 ... Bit deinterleaving unit, 208 ... Viterbi Decoding unit 209 Byte deinterleaving unit 210 210 Energy spreading unit 211 Reproducing unit 21 Decoding unit, 213 ... C / N ratio output unit, 214 ... BER output unit, 215 ... TS output unit, 301 ... Battery remaining amount / communication sensitivity etc. display unit, 302 ... Menu selection item display unit, 303 ... Broadcast display unit , 304 ... Communication display section, 305 ... Reception sensitivity display section, 501 ... Display screen, 502 ... Viewer current location point, 601 ... Video display section, 602 ... Antenna, 603 ... Speaker, 701 ... Broadcast display section, 702 ... Communication display , 703... Reception sensitivity display bar, 704.

Claims (2)

A receiving sensitivity parameter detecting means for detecting a receiving sensitivity parameter of digital broadcasting;
A reception status display means for displaying a reception status based on the reception sensitivity parameter on a display unit;
A portable terminal having a communication unit ,
When the reception sensitivity parameter detected by the reception sensitivity parameter detection means is such that digital broadcasting cannot be received,
The reception status display means, and displays the reception sensitivity on the display unit, the display and the message over the situation can not be received in the content display area of the digital broadcast of the display unit,
The mobile terminal, wherein the reception sensitivity and the message display are displayed on the display unit together with a communication sensitivity display by the communication unit . A receiving sensitivity parameter detecting means for detecting a receiving sensitivity parameter of digital broadcasting;
A reception status display means for displaying a reception status based on the reception sensitivity parameter on a display unit;
A portable terminal having a communication unit,
When the reception sensitivity parameter detected by the reception sensitivity parameter detection means is such that digital broadcasting cannot be received,
The reception status display means, and displays the message over the situation can not be received in the content display area of the digital broadcast of the display unit, a mobile, characterized in that to display the communication sensitivity display by the communication unit on the display unit Terminal.

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