JP5088045B2 - Digital broadcast receiver - Google Patents

Description

  The present invention relates to a digital broadcast receiving apparatus that receives a digital broadcast signal for a vehicle-mounted television.

  Conventionally, various receiving apparatuses for in-vehicle television have been developed. Since the electric field strength of the broadcast signal changes as the vehicle moves, a network follow function is provided that automatically switches to the channel of the affiliated station in the area where the vehicle is located (see, for example, Patent Document 1).

Analog broadcast signals may receive only audio signals due to differences in the carrier frequency band between video signals and audio signals even if the electric field strength decreases and video signals cannot be received. When the strength is lowered, it becomes impossible to receive both the video signal and the audio signal.
JP 2005-277727 A

  In order to ensure safety when the vehicle is traveling, images cannot be displayed while traveling, but sound can be output.

  Therefore, when receiving an analog broadcast signal, the signal level of the video signal is sufficient if the channel is automatically switched so that only the audio signal can be received in response to a change in the electric field strength of the broadcast signal or a change in the reception area. Even in areas that are not, it is possible to prevent the sound from being interrupted.

  However, in the case of a digital broadcast signal, both the video signal and the audio signal cannot be received due to a decrease in electric field strength as described above, and the received signal must be demodulated. Usually, this demodulation process requires about 2 seconds.

  For this reason, when outputting a sound signal while the vehicle is running, if a broadcast station is switched after the sound signal is interrupted due to a decrease in electric field strength, the demodulation process takes time, so an analog broadcast signal is received. There was a problem that the state in which the sound was interrupted was prolonged as compared with the case. Further, when the vehicle moves during demodulation processing and the electric field strength changes, the broadcast station that is automatically selected further changes, and there is a possibility that the state where the sound is interrupted will be further prolonged.

  An object of the present invention is to provide a digital broadcast receiving apparatus that can immediately output the contents of a digital broadcast signal of another broadcast station even if the signal level of the digital broadcast signal decreases due to movement of a vehicle or the like.

A digital broadcast receiver according to an aspect of the present invention receives a first digital broadcast signal from a broadcast station selected from a plurality of broadcast stations, demodulates the first digital broadcast signal, and outputs first broadcast data. The first tuner and the broadcast station selected by the first tuner are selected to receive the second digital broadcast signal, the second digital broadcast signal is demodulated, and the second broadcast data is received. A second tuner for outputting the signal, signal level detection means for detecting the signal level of each of the first digital broadcast signal and the second digital broadcast signal, and reproduction for reproducing the first broadcast data or the second broadcast data. Selection control means for selecting, from the first tuner or the second tuner, an output source of broadcast data to be transmitted to the means, wherein the selection control means uses the first tuner as the output source. When you are-option, the signal level of the first digital broadcast signal drops below a predetermined level, in advance the second tuner before switching the output source of the broadcast data from the first tuner to the second tuner The reception process of the second digital broadcast signal and the demodulation process of the second broadcast data are started.
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  In this case, the selection control means may switch the second broadcast data to the output source when the signal level of the first digital broadcast signal is lower than a predetermined level for a predetermined time.

  In this case, when the second tuner is selected as the output source by the selection control means and there are a plurality of receivable digital broadcast signals, the second tuner receives the signal from the broadcasting station with the highest signal level. Second broadcast data obtained by demodulating two digital broadcast signals may be sent to the reproducing means.

  According to the present invention, when the signal level of the digital broadcast signal decreases due to movement of the vehicle or the like, the other tuner receives the digital broadcast signal in advance and demodulates the broadcast data. Thus, it is possible to provide a specific effect that it is possible to provide a digital broadcast receiver that can immediately output the contents of digital broadcast signals of other broadcast stations.

  Embodiments to which the digital broadcast receiving apparatus of the present invention is applied will be described below.

  FIG. 1 is a diagram illustrating a configuration of a digital broadcast receiving apparatus according to the present embodiment. The digital broadcast receiving apparatus according to the present embodiment includes a diversity unit 10 built in a vehicle navigation apparatus 1.

  The navigation apparatus 1 uses a monitor 2 for indicating the current position of the vehicle on an electronic map, a speaker 3 for outputting voice guidance, a navigation ECU (not shown), and a satellite navigation system (GPS: Global Positioning System). A GPS receiver that calculates the current position and traveling speed of the vehicle is provided. The navigation device 1 only needs to be configured to provide desired guidance information to the user by deriving position data representing the position of the host vehicle on the electronic map using the map data. The speaker 3 may also be a speaker included in the vehicle acoustic system.

  The diversity unit 10 includes two tuner modules 11 and 12 and a selection control processing unit 13 that selects a video signal and an audio signal demodulated by the tuner modules 11 and 12.

  Diversity antennas 14 and 15 for receiving digital broadcast signals are connected to diversity unit 10. Digital broadcast signals received by the diversity antennas 14 and 15 are transmitted to the tuner modules 11 and 12 via an internal bus (not shown) in the diversity unit 10.

  The tuner modules 11 and 12 have a network follow function and demodulate the digital broadcast signals received by the diversity antennas 14 and 15 to obtain broadcast data. Each of the tuner modules 11 and 12 can receive one or a plurality of digital broadcast signals from one or a plurality of broadcast stations according to the reception status at that time, and demodulates the received one or a plurality of digital broadcast signals. Output one or more broadcast data.

  The selection control processing unit 13 is configured around a microcomputer including a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like via a bus (not shown). The selection control processing unit 13 transmits broadcast data (including a video signal and an audio signal) obtained from either the tuner module 11 or 12 to the monitor 2 and the speaker 3 and outputs video and audio. In addition, it is comprised so that an image | video may not be output to the monitor 2 during driving | running | working of a vehicle. For example, the selection control processing unit 13 monitors the detection signal of the shift position sensor, and permits the video to be output to the monitor 2 only when it is detected that it is a parking position. In this case, it is realized by configuring so as not to permit.

  In addition, the selection control processing unit 13 transmits the broadcast data obtained from either the tuner module 11 or 12 to the monitor 2 and the speaker 3, and the signal level of the digital broadcast signal before the demodulation process is below a predetermined level. Then, among the broadcast data demodulated by the other tuner module (11 or 12), the broadcast data (including the video signal and the audio signal) having the highest signal level of the digital broadcast signal before the demodulation process is displayed on the monitor 2 and the speaker. 3 is transmitted. This process will be described with reference to FIG.

  FIG. 2 is a diagram illustrating a processing procedure performed by the selection control processing unit of the digital broadcast receiving apparatus according to the embodiment.

  When the TV tuner is turned on by the user, the selection control processing unit 13 executes the process shown in FIG. 2 (start).

  The selection control processing unit 13 determines whether broadcast data obtained by demodulating the digital broadcast signal is being output from the monitor 2 and the speaker 3 (step S1). As described above, since the video is not displayed on the monitor 2 while the vehicle is traveling, the selection control processing unit 13 determines whether or not sound is output from the speaker 3 while the vehicle is traveling.

  If the selection control processing unit 13 determines in step S1 that the broadcast data is being output from the monitor 2 and the speaker 3, the signal level of the digital broadcast signal corresponding to the broadcast data being output from the monitor 2 and the speaker 3 is determined. It is determined whether it is below the first predetermined level (step S2). This process is a process for detecting in advance that video and audio are interrupted, and the first predetermined level is set to a signal level at which broadcast data (video data and audio data) cannot be obtained from a digital broadcast signal. The signal level may be set to a margin added.

  The process of step S2 is repeatedly executed until it is determined that the signal level is equal to or lower than the first predetermined level. Similarly to the processing in step S2, since the video is not displayed on the monitor 2 while the vehicle is traveling, the selection control processing unit 13 is digital corresponding to the broadcast data being output from the speaker 3 while the vehicle is traveling. It is determined whether or not the signal level of the broadcast signal is equal to or lower than a first predetermined level.

  Here, for convenience of explanation, it is assumed that the digital broadcast signal received by the tuner module 11 is demodulated and output from the monitor 2 and the speaker 3.

  When the selection control processing unit 13 determines that the signal level is equal to or lower than the first predetermined level, the selection control processing unit 13 counts the time during which the signal level is equal to or lower than the first predetermined level with the internal clock (step S3).

  The selection control processing unit 13 determines whether the time counted by the internal clock is equal to or longer than a predetermined time (step S4). This process is repeatedly executed until a predetermined time is reached.

  The selection control processing unit 13 causes the tuner module 12 to receive a digital broadcast signal and demodulates the received digital broadcast signal into broadcast data (step S5). This is because when the signal level of the digital broadcast signal received by the tuner module 11 falls below the first predetermined level, the other tuner module receives and demodulates the signal in advance (switching the back channel) in order to switch the tuner module. This is because it is executed as a process. Since it takes time to demodulate the digital broadcast signal, if such a back process is performed, the broadcast data is sent to the monitor 2 and the speaker 3 without waiting for the time for the demodulation process when the tuner module is switched. Can be output.

  The selection control processing unit 13 determines whether one or a plurality of digital broadcast signals received by the tuner module 12 includes a signal level equal to or higher than a second predetermined level (step S6). The process of step S6 is repeatedly executed until a broadcast station that outputs a digital broadcast signal having a signal level equal to or higher than the second predetermined level is found.

  The second predetermined level may be a signal level of a digital broadcast signal that can be obtained by demodulation of broadcast data that does not interfere with output from the monitor 2 and the speaker 3.

  When a broadcast station that outputs a digital broadcast signal having a signal level equal to or higher than the second predetermined level is found, the selection control processing unit 13 finds the broadcast data to be output to the monitor 2 and the speaker 3 in step S6. Switch to (channel) (step S7). Specifically, the tuner module to be selected is switched from the tuner module 11 to the tuner module 12, and when there are a plurality of digital broadcast signals received by the tuner module 12 having a signal level equal to or higher than the second predetermined level. Then, broadcast data of the broadcasting station (channel) having the highest signal level is selected and output to the monitor 2 and the speaker 3.

  As described above, the selection control processing unit 13 switches the output source of the broadcast data to the monitor 2 and the speaker 3 to the tuner module 12, whereby the processing procedure shown in FIG.

  As described above, according to the digital broadcast receiving apparatus of the present embodiment, when the signal level of the digital broadcast signal being received is lowered to some extent, the other tuner module demodulates the broadcast data in advance by the back tuning process. Therefore, when the tuner module is switched, the broadcast data can be output immediately without interruption.

  In particular, when broadcast data is interrupted while the vehicle is moving, noise is output from the speaker 3, which may make the driver and other occupants feel bothersome, but the digital broadcast receiving apparatus of the present embodiment Therefore, as long as the other tuner module can receive the above-described digital broadcast signal of the second predetermined level or higher, such inconvenience can be eliminated.

  In some areas, the same program is broadcast on different broadcast stations (channels). In such a case, the program can be prevented from being interrupted by switching the tuner module and changing the broadcasting station (channel).

  In the above description, the case where the tuner module 11 is switched to the tuner module 12 while receiving a digital broadcast signal has been described. However, since the functions of the tuner modules 11 and 12 included in the diversity unit 10 are the same, On the contrary, when the signal level of the digital broadcast signal received by the tuner module 12 decreases, the tuner module 11 may be switched.

[Modification]
FIG. 3 is a diagram illustrating a configuration of a modified example of the digital broadcast receiving apparatus according to the embodiment. The digital broadcast receiving apparatus of the present embodiment is different from the digital broadcast receiving apparatus shown in FIG. 1 in that the diversity unit 10 is not built in the navigation apparatus 1 of the vehicle but is arranged outside the navigation apparatus 1. .

  Other configurations are in accordance with the digital broadcast receiving apparatus shown in FIG. 1, and the control processing by the selection control processing unit 13 is the same procedure as shown in FIG.

  As described above, even when the signal level of the digital broadcast signal being received is reduced to some extent by the configuration attached to the outside of the navigation apparatus 1, the other tuner module demodulates the broadcast data by the back channel selection process in advance. Therefore, it is possible to prevent the broadcast data from being interrupted.

  The digital broadcast receiving apparatus according to the exemplary embodiment of the present invention has been described above. However, the present invention is not limited to the specifically disclosed embodiment, and departs from the scope of the claims. Various modifications and changes are possible.

It is a figure which shows the structure of the digital broadcast receiver of embodiment. It is a figure which shows the process sequence by the selection control process part of the digital broadcast receiver of embodiment. It is a figure which shows the structure of the modification of the digital broadcast receiver of embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Navigation apparatus 2 Monitor 3 Speaker 10 Diversity unit 11, 12 Tuner module 13 Selection control processing part 14, 15 Diversity antenna

Claims (3)

A first tuner that receives a first digital broadcast signal from a broadcast station selected from a plurality of broadcast stations, demodulates the first digital broadcast signal, and outputs first broadcast data;
A second tuner that selects a broadcast station different from the broadcast station selected by the first tuner, receives a second digital broadcast signal, demodulates the second digital broadcast signal, and outputs second broadcast data. When,
Signal level detection means for detecting the signal level of each of the first digital broadcast signal and the second digital broadcast signal;
Selection control means for selecting, from the first tuner or the second tuner, an output source of broadcast data to be transmitted to a reproducing means for reproducing the first broadcast data or the second broadcast data;
When the first tuner is selected as the output source and the signal level of the first digital broadcast signal falls below a predetermined level, the selection control means sets the broadcast data output source to the first tuner. A digital broadcast receiving apparatus that causes the second tuner to start receiving the second digital broadcast signal and demodulating the second broadcast data in advance before switching to the second tuner.   2. The digital broadcast reception according to claim 1, wherein the selection control unit switches the second broadcast data to the output source when a signal level of the first digital broadcast signal is lower than a predetermined level for a predetermined time. apparatus.   The second tuner demodulates the second digital broadcast signal received from the broadcast station having the highest signal level when there are a plurality of receivable digital broadcast signals when the selection control means selects the output source. The digital broadcast receiving apparatus according to claim 2, wherein the second broadcast data obtained in this way is sent to the reproduction means.

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