JP4655556B2 - Digital broadcast receiver - Google Patents

Description

  The present invention relates to an apparatus for receiving a digital television broadcast such as a television receiver, a set-top box, a personal computer, a mobile phone, and the like, particularly when mounted on a vehicle.

  In recent years, digital broadcasting has progressed. The development of portable and mobile receivers as well as fixed receivers for viewing at home is progressing and is expected to be commercialized in the future.

  In digital television broadcasting, if the reception state falls below a certain level, decoding cannot be performed and audio / video cannot be output. In the case of in-vehicle use, if the audio / video is suddenly interrupted, there is a possibility that it may lead to a side-view driving by misunderstanding that the user has failed.

  As a means for solving this problem, a technique as disclosed in Patent Document 1 is disclosed. In this case, when the broadcast radio wave is interrupted due to an obstacle or the like, the image displayed before the interruption is output as a still image, so that the image is continuously displayed without being interrupted.

Thus, it has already been done to avoid a situation where nothing appears due to the reception state.
JP 9-37163 A

  However, the conventional example as in Patent Document 1 has the following problems.

  In analog television broadcasting, audio may be output even when video is interrupted, but in digital television broadcasting, audio is also interrupted.

  Therefore, a still image can be displayed for video, but there is a problem that nothing can be output for audio.

  Next, there is a problem of misinterpreting that a failure has occurred because outputting the video displayed before the interruption as a still image is an operation different from that of a conventional television used by a user at home.

  It is an object of the present invention to provide a digital broadcast receiver that solves the above-mentioned conventional problems.

  In the first invention of the present invention, decoding means for receiving a digital television broadcast and decoding and outputting a video signal and an audio signal, a detecting means for detecting a reception state of the digital television broadcast, and white noise Audio noise generating means for generating and outputting, audio switching means for switching and outputting the audio signal output by the decoding means or the white noise output by the audio noise generating means, and the detection means according to the detection result of the detection means Control means for controlling switching of the voice switching means.

  According to a second aspect of the present invention, in the first aspect, the video noise generating means for generating and outputting a video noise such as a sandstorm displayed in a weak electric field state in the analog television receiver, and the decoding means And a video switching means for switching and outputting the video noise output from the video noise generating means.

  According to a third aspect of the present invention, in the second aspect of the invention, the audio noise generation means includes: audio noise storage means for storing white noise data; and video noise storage means for storing the video noise data. Generates audio noise using white noise data stored in the audio noise storage means, and the video noise generation means uses video noise data stored in the video noise storage means to generate video noise. Is generated.

  According to a fourth aspect of the present invention, in the first aspect, the control means for controlling to switch to the white noise output from the audio noise generating means when the reception state of the digital television broadcast is worse than a predetermined level. It is characterized by providing.

  According to a fifth aspect of the present invention, in the first aspect, the detection means detects a reception state based on an electric field strength.

  According to a sixth aspect of the present invention, in the first aspect, the detection means detects a reception state based on a bit error rate.

  According to a seventh aspect of the present invention, in the first aspect, the detection means detects a reception state based on a lock state in demodulation.

  The digital broadcast receiver according to the present invention can generate a video image such as a sandstorm like a conventional analog television and a noise sound and output the video / audio even if the reception state deteriorates. The image and noise sound like a sandstorm are the same as when the reception condition deteriorated in a conventional analog TV, and it can be safely operated without misunderstanding that the driver in the in-vehicle digital TV receiver has failed. .

  Hereinafter, the best mode for carrying out the invention will be described with reference to the drawings.

  A first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a digital broadcast receiver according to the present invention. In the digital broadcast receiver 1 shown in FIG. 1, an antenna 2, a receiver 3, a demodulator 4, a decoder 5, an electric field strength detector 6, an audio noise memory 7, a video noise memory 8, a controller 9, an input unit 10, audio The circuit includes a noise generation circuit 11, a video noise generation circuit 12, an audio switching unit 13, a video switching unit 14, an audio output unit 15, and a video output unit 16.

  The receiver 3 receives the digital television broadcast received from the antenna 2 and selects a television broadcast signal modulated by a transmission channel desired by the user under the control of the controller 9 described later. The demodulator 4 receives the modulated signal output from the receiver 3, demodulates it, and outputs an MPEG-2 transport stream. In digital television broadcasting, it is well known to modulate and broadcast an MPEG-2 transport stream. The demodulator 4 detects and outputs the electric field strength when receiving the desired transmission channel. It is common to detect and output electric field strength as a function of the LSI constituting the demodulator.

  The decoder 5 receives the MPEG-2 transport stream output from the demodulator 4, extracts the video / audio stream of the program desired by the user, decodes it, and outputs the analog Y / Pb / Pr video signal. Outputs analog L / R audio signals.

  The electric field strength detector 6 receives the electric field strength data output from the demodulator 4 and compares it with a predetermined electric field strength level. Then, the result of whether the electric field strength is higher or lower than a predetermined level is output to the control unit 9 described later.

  The audio noise memory 7 stores audio noise data. The video noise memory 8 stores video noise data. The audio noise data is white noise data such as “Zar” that is output when the reception state of the analog receiver deteriorates. The video noise data is video data such as a sandstorm that is output when the reception state of the analog receiver deteriorates. These audio noise and video noise data are used to simulate a state in which the reception state of the analog receiver has deteriorated.

  These data are written when the digital broadcast receiver is shipped. The control unit 9 is a microcomputer that controls each component of the digital broadcast receiver 1. The control unit 9 is connected so that data stored in the audio noise memory 7 and the video noise memory 8 can be read. The input unit 10 is an interface for receiving an operation from the user. For example, a remote control or a keyboard can be considered. User operations are converted into electrical signals by the input unit 10 and input to the control unit 9.

  The audio noise generation circuit 11 inputs audio noise data stored in the audio noise memory 7 read by the control unit 9, generates an analog L / R audio noise signal, and outputs it. For example, an audio noise signal stored as PCM data is input, repeatedly decoded, and output after D / A conversion. The video noise generation circuit 12 inputs video noise data stored in the video noise memory 8 read by the control unit 9, generates an analog Y / Pb / Pr video noise signal, and outputs it. For example, a video noise signal stored as bitmap data is input, repeatedly decoded, and output after D / A conversion.

  The audio switching unit 13 inputs the analog L / R audio signal from the decoder 5 and the analog L / R audio noise signal from the audio noise generation circuit 11, and switches and outputs them under the control of the control unit 9. Instead of switching, it is also possible to synthesize at a predetermined ratio. The video switching unit 14 inputs the analog Y / Pb / Pr video signal from the decoder 5 and the analog Y / Pb / Pr video noise signal from the video noise generation circuit 12, and switches and outputs them under the control of the control unit 9. To do. Instead of switching, it is also possible to synthesize at a predetermined ratio.

  The audio output unit 15 receives analog L / R audio signals from the audio switching unit 13, amplifies the audio signals, and outputs them to a speaker (not shown). The video output unit 16 receives analog Y / Pb / Pr video signals from the video switching unit 14 and amplifies the video signals. Further, after extracting the synchronization signal multiplexed with the analog Y signal, the video signal amplified in synchronization with the synchronization signal is output to a monitor (not shown). The electric field intensity detection unit 6 may be performed by software control of the control unit 9.

  In the present embodiment, the electric field intensity detection unit 6 inputs electric field intensity data and compares it with a predetermined level, but other data may be used. For example, the bit error rate data and the data indicating the lock / unlock of the demodulator may be input from the demodulator 4 and compared.

  FIG. 2 is a flowchart showing the operation of the digital broadcast receiver of the present invention. The operation will be described with reference to FIG. The receiving unit 3 receives the broadcast from the antenna 2. The control unit 9 controls the receiving unit 3 so as to select the program selected by the user using the input unit 10 (step S0).

  The demodulator 4 demodulates the program selected by the user in step S0. The electric field strength detection unit 6 grasps the electric field strength of the program desired by the user detected by the demodulation unit 4 (step S1).

  Then, a comparison with a predetermined level is performed. The process is divided into step S3 and step S5 according to the comparison result (step S2).

  When the control unit 9 recognizes the result of comparison in step S2 and the electric field strength is lower than a predetermined level, the control unit 9 reads the audio noise data from the audio noise memory 7, and the audio noise generation circuit 11 performs analog processing. Control is performed so that an L / R audio noise signal is generated. Also, the video noise data is read from the video noise memory 8 and controlled so that the video noise generation circuit 12 generates an analog Y / Pb / Pr video noise signal (step S5).

  Next, the control unit 9 controls the audio switching unit 13 to output analog L / R audio noise generated from the audio noise generation circuit 11. The video switching unit 14 controls to output analog Y / Pb / Pr video noise generated from the video noise generating circuit 12 (step S6).

  On the other hand, when the electric field strength is higher than the predetermined level, the control unit 9 controls to extract and decode the MPEG-2 transport stream of the program selected by the user using the input unit 10 (step S3). .

  Next, the control unit 9 controls the audio switching unit 13 to output the analog L / R audio output from the decoder 5. The video switching unit 14 controls to output the analog Y / Pb / Pr video output from the decoder 5 (step S4).

  In this embodiment, steps S3 and S5 are operated based on the comparison result of step S2. However, the controller 9 can be operated in advance, and the control unit 9 simply switches between the audio switching unit 13 and the video switching unit 14. good.

  As described above, the digital broadcast receiver according to the first embodiment of the present invention detects the electric field strength when digital television broadcast is received, recognizes a state where decoding is not possible, and determines the conventional state according to the recognition result. It can generate sandstorms and noise sounds like analog TV and output video and audio.

  The digital broadcast receiver according to the present invention is misunderstood that the driver in the in-vehicle digital television receiver has failed by generating the image and noise sound like a sandstorm like a conventional analog television and outputting the image / sound. Therefore, it is useful as a television receiver, a set top box, a personal computer, a mobile phone and the like.

The block diagram which showed the structure of the digital broadcast receiver of this invention The flowchart which shows operation | movement of the digital broadcast receiver of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Digital broadcast receiver 2 Antenna 3 Receiver 4 Demodulator 5 Decoder 6 Electric field strength detector 7 Audio noise memory 8 Video noise memory 9 Control unit 10 Input unit 11 Audio noise generator 12 Video noise generator 13 Audio switch 14 Video Switching unit 15 Audio output unit 16 Video output unit

Claims (4)

Decoding means for receiving a digital television broadcast and decoding an analog Y / Pb / Pr video signal;
Detecting means for detecting a receiving state of the digital television broadcast;
Video noise storage means for storing video noise bitmap data;
Video noise generating means for repeatedly decoding and D / A converting using the video noise bitmap data stored in the video noise storage means to generate an analog Y / Pb / Pr video noise signal;
Switching between the analog Y / Pb / Pr video signal as the output of the decoding means and the analog Y / Pb / Pr video noise signal as the output of the video noise generating means based on a command from the control means described later. Video switching means for output,
Control means for controlling switching of the video switching means based on the detection result of the detection means;
A digital broadcast receiver. 2. The digital broadcast receiver according to claim 1 , wherein the detection unit detects a reception state based on an electric field intensity. 2. The digital broadcast receiver according to claim 1 , wherein the detection means detects a reception state based on a bit error rate. 2. The digital broadcast receiver according to claim 1 , wherein the detecting means detects a reception state based on a lock state in demodulation.

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