JP3920861B2 - Digital broadcast receiver - Google Patents

Description

  The present invention relates to a digital broadcast receiving apparatus that receives a digital broadcast.

In digital broadcasting using terrestrial waves, a transmission method called OFDM (Orthogonal Frequency Division Multiplexing) is used, and as a digital broadcast receiving device that receives the broadcast waves, in addition to a receiving device that is fixedly installed in a house. It is assumed to be used as a device (hereinafter referred to as a portable device) that is intended to be used in a mobile device having a reception function added or a moving body such as a car. 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, for example, 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. For portable devices, strong hierarchy broadcasting and middle hierarchy broadcasting are performed. The fixed receiver is configured to be able to receive all layers (however, since the quality of video / audio data included in the strong layer is inferior to the quality of video / audio data in the weak layer, it is generally not used. In addition, the PDI / SI for control may be the one included in the strong hierarchy.) The mobile receiver is configured to be able to receive the middle hierarchy and the strong hierarchy. It is configured to be able to receive a strong hierarchy. That is, the portable device is not configured to receive weak hierarchical broadcasting. Note that there is known an equalizer that can obtain good reception characteristics regardless of whether the reception mode is fixed position reception or mobile reception (see Patent Document 1).
JP 2003-283392 A

  Since the weaker broadcast has better image quality than the stronger and middle-tier broadcasts, the tuner for fixed receivers (a tuner that can receive all of the strong, middle, and weaker layers) is installed in the portable device. It is conceivable to operate the tuner for weak hierarchy broadcasting or middle hierarchy broadcasting when the radio wave condition is stable, while operating the tuner for strong hierarchy broadcasting when the radio wave condition is unstable.

  However, this makes it impossible to present the received video stably at the time of layer switching.

  An object of this invention is to provide the digital broadcast receiver which can show a received image stably in view of said situation.

  In order to solve the above-described problems, a digital broadcast receiving apparatus according to the present invention includes a first receiver that receives at least a weak hierarchical broadcast of a digital broadcast and generates video and audio, and a middle broadcast and / or strong broadcast of the digital broadcast. A second receiving unit that receives hierarchical broadcast and generates video and audio, and a selection unit that selects one of the first and second receiving units and the video and audio output to supply to the video display unit and the audio output unit And a control means for providing a selection command signal to the selection means, and is configured to be portable, and both the first reception unit and the second reception unit are configured to be capable of performing a reception operation simultaneously. It is characterized by.

  If it is said structure, a high quality image | video can be shown by the broadcast reception in a 1st receiving part. On the other hand, when it is difficult to receive the broadcast at the first receiving unit, it is possible to switch to the received video display at the second receiving unit, so that the broadcast viewing of the same program can be continued although the image quality is lowered. Furthermore, since both the first receiving unit and the second receiving unit operate simultaneously to present video and audio, switching is performed smoothly, and the received video can be presented stably.

  In the digital broadcast receiving apparatus having the above configuration, the control means gives a command to the selection means to select the video / audio of the first receiving unit when the video / audio output is performed by the first receiving unit. It is good. Alternatively, a means for determining the received signal quality in each receiving unit may be provided, and the control means may give a selection command signal based on the received signal quality.

  In the digital broadcast receiving apparatus having these configurations, the control means is driven by the attached battery, and the control means stops energization to the first receiving unit and the second receiving unit when the remaining battery level falls below a predetermined value. It is also possible to select the video and audio output from. Alternatively, a switch operated by a user is provided, and when the low power consumption mode is selected by the switch, the control unit stops energization to the first receiving unit and is output from the second receiving unit. Video and audio may be selected. Or it is comprised as a vehicle-mounted type | mold, When the said control means detects engine OFF, it is good also as selecting the video and audio | voice output from a 2nd receiving part while stopping electricity supply to a 1st receiving part. With these configurations, it is possible to reduce power consumption and extend the receivable time.

  According to the present invention, since both the first receiving unit and the second receiving unit operate simultaneously and can present video and audio, the switching can be performed smoothly and the received video can be presented stably. In a configuration including a mode in which both the first receiving unit and the second receiving unit are not operated simultaneously, power consumption can be reduced.

  An embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a block diagram of a portable (portable or vehicle-mounted) digital broadcast receiver capable of receiving terrestrial digital broadcast waves.

  The antenna 1 receives a digital broadcast wave transmitted from a terrestrial broadcast station. The first tuner 2A and the second tuner 2B take out a signal of a specific frequency from the high frequency digital modulation signal including video / audio data. Further, the tuners 2A and 2B include a demodulation circuit, a deinterleave circuit, an error correction circuit, and the like, thereby demodulating the selected digital modulation signal and outputting a transport stream. In this embodiment, the first tuner 2A is configured to receive at least a weak layer broadcast (broadcast for a fixed device), and the second tuner 2B is a strong layer broadcast and / or a middle layer broadcast (broadcast for mobile terminals and / or Broadcast for mobile devices). The tuners 2A and 2B basically operate by receiving power supply at the same time.

  The first decoder unit 3A inputs the transport stream from the first tuner 2A, and the second decoder unit 3B inputs the transport stream from the second tuner 2B. The decoder units 3A and 3B basically operate by receiving power supply at the same time.

  The decoder units 3A and 3B separate the transport stream into, for example, MPEG (Moving Picture Experts Group) video stream, audio stream, PSI / SI (Program Specific Information / Service Information), and the like into PSI / SI. The included program information and the like are supplied to the CPU 4. As described above, a plurality of channels are multiplexed in the transport stream, and processing for selecting an arbitrary channel from among these is performed in the transport stream from the PSI / SI. Thus, it becomes possible by taking out data such as which packet ID is multiplexed.

  The decoder units 3A and 3B include a video decoder that decodes a video stream and an audio decoder that decodes an audio stream. The video decoder decodes the input variable length code to obtain a quantization coefficient and a motion vector, and performs inverse DCT conversion, motion compensation control based on the motion vector, and the like. The audio decoder decodes the input encoded signal to generate audio data. In addition, the decoder units 3A and 3B perform D / A conversion on the video data generated by the decoding, for example, convert it into a composite video signal, and perform D / A conversion on the audio data generated by the decoding. For example, a right (R) sound analog signal and a left (L) sound analog signal are generated.

  The switching circuit 5 receives the video / audio signal from the first decoder unit 3 </ b> A and the video / audio signal from the second decoder unit 3 </ b> B, and selects either of them according to a switching command given from the CPU 4. The video / audio signal selected by the switching circuit 5 is applied to a video display panel and a speaker (not shown).

  The CPU 4 performs the following processing (1) or (2).

  (1) The CPU 4 controls the tuners 2A and 2B to receive the same channel (service). The CPU 4 obtains, for example, an error rate from the tuners 2A and 2B, and determines whether or not the tuners 2A and 2B can receive broadcasts. When the tuners 2A and 2B determine that reception is possible, a command is given to the switching circuit 5 to select the output video / audio signal of the first decoder unit 3A (fixed broadcast receiving system). When the first tuner 2A determines that reception is not possible, a command is given to the switching circuit 5 so as to select the output video / audio signal of the second decoder unit 3B (e.g., broadcast receiving system for portable terminals). When both tuners 2A and 2B determine that reception is not possible, an OSD circuit (on-screen display circuit) (not shown) displays a text message “cannot be received”.

  (2) The CPU 4 controls the tuners 2A and 2B to receive the same channel (service). The CPU 4 receives a signal indicating the received signal quality from the tuner 2A. As a signal indicating the received signal quality, C / N ratio, intermediate signal strength, error rate, and the like can be used. The CPU 4 compares a reference value stored in a memory (not shown) with the received signal quality from the tuner 2A, and determines whether the received signal quality is equal to or higher than the reference value. The reference value is, for example, a value that can be received sufficiently by weak hierarchical broadcasting. If the received signal quality is equal to or higher than the reference value, the CPU 4 gives a command to the switching circuit 5 to select the output video / audio signal of the first decoder unit 3A. In other cases, a command is given to the switching circuit 5 to select the output video / audio signal of the second decoder unit 3B. Note that the received signal quality may be sampled at a predetermined interval to determine the tendency of the received signal quality instead of simply comparing with the reference value. In this case, when it is predicted that the weak-layer broadcast cannot be received after a few seconds due to a downward trend (although the received video can be presented by the first decoder unit 3A at that time), the first decoder unit 3A An output video / audio signal may be selected.

  In the above-described controls (1) and (2), high-quality video can be presented by enabling broadcast reception in the fixed broadcast reception system. On the other hand, when it is difficult to receive a broadcast in the fixed broadcast reception system, it is possible to switch to the broadcast reception system such as for a portable terminal, so that the broadcast viewing of the same program can be continued although the image quality is lowered. Further, since both the fixed broadcast receiving system and the portable receiving system such as the portable terminal are in a state in which both can operate simultaneously and present video and audio, the switching can be performed smoothly and the received video can be presented stably.

  In some cases, both the fixed broadcast receiving system and the mobile terminal and other broadcast receiving system are not operated simultaneously. When not operating simultaneously, power consumption can be reduced. In order to individually operate the fixed broadcast receiving system and the broadcast receiving system such as for mobile terminals, an individual power supply system and a switch for ON / OFF control of each system may be provided. This will be described below.

[When the digital broadcast receiver is configured to be battery-powered]
The CPU 4 receives a signal indicating the remaining battery level from a remaining battery level detection unit (not shown). When the remaining battery level falls below a predetermined value, the CPU 4 stops the operation of the fixed broadcast receiving system (power supply is stopped). Then, a command is given to the switching circuit 5 so as to select the video / audio output by the broadcast receiving system for portable terminals or the like.

[When the digital broadcast receiver is configured in-vehicle]
In the ignition key switch of the car, four positions of OFF-Acc-ON-Egn are set, which are the respective states at the time of parking, power supply to electrical components, engine ON, and starter motor operation. The in-vehicle digital broadcast receiving apparatus receives power from an in-vehicle battery (not shown) when the ignition key switch is in the Acc state and is ON. Further, the CPU 4 of the digital broadcast receiving apparatus is configured to receive a signal indicating whether the Acc is ON or ON from the ignition key switch. The CPU 4 determines the ON / OFF state of the engine based on the state of the ignition key switch. Then, when the engine is OFF, the operation of the fixed broadcast receiving system is stopped (power supply is stopped), and a command is given to the switching circuit 5 to select the video and audio output by the broadcast receiving system for mobile terminals and the like. .

[When installing a manual switch on the digital broadcast receiver]
Such a manual switch is a switch for switching between a normal mode and a low power consumption mode. The normal mode is a mode in which both the fixed broadcast receiving system and the mobile terminal and the like broadcast receiving system are simultaneously operated, and the low power consumption mode is the mode in which only the mobile terminal and the like broadcast receiving system is operated. When the low power consumption mode is selected by the switch, the CPU 4 stops the operation of the fixed broadcast receiving system (power supply is stopped), and selects the video / audio output by the broadcast receiving system for portable terminals, etc. Thus, a command is given to the switching circuit 5.

  Note that the fixed broadcast receiving system and the broadcast receiving system for mobile terminals do not need to be separately configured as chips, and the fixed broadcast receiving circuit and the mobile receiver broadcast receiving circuit are built on the same chip. But you can.

1 is a block diagram showing a digital broadcast receiver according to an embodiment of the present invention.

Explanation of symbols

2A 1st tuner 2B 2nd tuner 3A 1st decoder part 3B 2nd decoder part 4 CPU
5 switching circuit

Claims (6)

A first receiving unit for performing channel selection processing, demodulation processing, and decoding processing for receiving at least a weak layer broadcast of the digital broadcast and generating video and audio signals; and a middle layer broadcast and / or a strong layer of the digital broadcast a second receiving unit that performs a channel selection processing and the demodulation processing and decoding processing for generating the video and audio signals by receiving a broadcast, the first receiving portion and one of the video and audio of the second receiver A selection unit configured to select a signal and supply the selected signal to the video display unit and the audio output unit; and a control unit configured to supply a selection command signal to the selection unit. 2. A digital broadcast receiving apparatus, wherein the two receiving units are configured such that both of them can simultaneously receive signals. 2. The digital broadcast receiving apparatus according to claim 1, wherein the control means instructs the selection means to select the video / audio of the first receiving unit when the video / audio output is performed by the first receiving unit. A digital broadcast receiver characterized in that 2. The digital broadcast receiving apparatus according to claim 1, further comprising means for determining received signal quality in each receiving unit, wherein the control means gives a selection command signal based on the received signal quality. apparatus. 4. The digital broadcast receiving apparatus according to claim 1, wherein the control unit is driven by an attached battery, and the control unit sends the first receiving unit when the remaining battery level falls below a predetermined value. The digital broadcast receiving apparatus is characterized in that the video and audio output from the second receiving unit are selected while the energization is stopped. 4. The digital broadcast receiving apparatus according to claim 1, further comprising a switch operated by a user, wherein the control unit is configured to perform a first operation when a low power consumption mode is selected by the switch. A digital broadcast receiving apparatus characterized by stopping energization to a receiving unit and selecting video and audio output from the second receiving unit. 4. The digital broadcast receiver according to claim 1, wherein the digital broadcast receiver is configured as a vehicle-mounted type, and when the control unit detects that the engine is OFF, the energization to the first receiving unit is stopped and the second unit is set. A digital broadcast receiver characterized by selecting video and audio output from a receiver.

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