JP6293572B2 - Broadcast receiver and mute control method thereof - Google Patents

Description

  The present invention relates to a technique for muting an audio output in a broadcast receiver.

  As a technique for muting the audio output in the broadcast receiver, in a broadcast receiver that receives DAB (Digital Audio Broadcasting) popular in Europe, an FIC (Fast Information Channel) included in a DAB transmission frame is used. A technique for muting an audio output in accordance with an error rate of a high-speed information channel) and an error rate of an MSC (Main Service Channel) is known (for example, Patent Document 1).

  The FIC of the DAB transmission frame is a channel for transmitting information related to a broadcasting service such as information necessary for the receiver to select a program and auxiliary information for the program, and the MSC is a broadcast of voice and data. This is a channel in which subchannels (Sub Channels) for transmitting contents are aggregated.

JP 2001-223916 A

  As described above, when the audio output is muted in accordance with the FIC error rate and the MSC error rate, if both the FIC error rate and the MSC error rate are considered, both the FIC and the MSC are received. Therefore, when the reception failure occurs, it takes a relatively long time to start muting.

  On the other hand, if only the error rate of the FIC is considered, since the FIC is arranged before the MSC in the DAB transmission frame, muting can be started in a relatively short time when a reception failure occurs. However, if this is done, the audio output will be muted even if the error rate of the MSC to which the audio data to be output is transmitted is not defective.

  Further, when the error rate of only one of the error rate of the FIC and the error rate of the MSC is bad, the degree of reception failure is slight, and there is a high probability that the reception failure is recovered quickly. It is not always appropriate to mute the audio output considering only one of the error rate and MSC error rate.

  Accordingly, an object of the present invention is to appropriately perform mute of audio output promptly in a broadcast receiver.

  In order to achieve the above object, the present invention provides a broadcast for transmitting a transmission frame including information data representing information related to a broadcast service and audio data of a program provided by the broadcast service in each order on each frequency channel. To the broadcast receiver that outputs the audio represented by the audio data as audio, radio wave environment detecting means for detecting whether the received radio wave environment of the frequency channel being received is good or bad, and the information data of the received transmission frame Information data error rate detecting means for detecting good / bad error rate, audio data error rate detecting means for detecting good / bad error rate of the audio data of the received transmission frame, and audio for muting the audio output Output mute control means. However, when the radio wave environment detection unit detects a defect in the reception radio wave environment, the audio output mute control unit detects when the information data error rate detection unit detects a defect in the error rate of the information data. When the audio output is muted and the radio wave environment detection means detects a good reception radio wave environment, the information data error rate detection means detects a failure in the error rate of the information data in the transmission frame. When the audio data error rate detection means detects a failure in the error rate of the audio data of the transmission frame, the audio output is muted.

  Here, in such a broadcast receiver, when the audio output is muted in the audio output mute control means, the information data error rate detection means detects a good error rate of the information data in the transmission frame. In addition, when the audio data error rate detecting means detects a good error rate of the audio data of the transmission frame, the audio output mute may be released.

  In the above broadcast receiver, the broadcast may be broadcast by DAB (Digital Audio Broadcasting). In this case, the information data is transmitted using FIC (Fast Information Channel) of a DAB transmission frame. The audio data is audio data that is transmitted using the subchannel to be received in the MSC (Main Service Channel) of the DAB transmission frame.

  According to the broadcast receiver of the present invention, when a good reception radio wave environment is detected, a failure in the error rate of the information data in the transmission frame is detected, and the transmission frame following the information data is detected. The audio output is muted when a failure in the error rate of the audio data is detected.

On the other hand, when a defect in the reception radio wave environment is detected, the audio output is muted when a defect in the error rate of the information data in the transmission frame is detected.
Therefore, when a reception radio wave environment defect is detected, audio output mute can be started more quickly than when a reception radio wave environment condition is detected. Also, if the error rate of the information data is bad and the reception radio wave environment is bad, the bad error rate of the information data is due to the bad reception radio wave environment. Since the influence of the reception radio wave environment is equally applied to the audio data, the error rate of the audio data is considered to be poor.

  Therefore, if the reception radio wave environment is poor in this way, even if the mute is started only according to the error rate of the information data, it is inappropriate even though the error rate of the audio data is good There is a high probability that it will not be muted.

  Therefore, according to the present broadcast receiver, prompt audio output mute can be appropriately performed.

  As described above, according to the present invention, audio output can be appropriately muted promptly in a broadcast receiver.

It is a block diagram which shows the structure of the broadcast receiver which concerns on embodiment of this invention. It is a figure which shows the transmission frame which the broadcast receiver which concerns on embodiment of this invention receives. It is a flowchart which shows the output mute process which concerns on embodiment of this invention. It is a figure which shows the process example of the output mute process which concerns on embodiment of this invention.

Hereinafter, embodiments of the present invention will be described.
FIG. 1 shows a configuration of a broadcast receiver according to the present embodiment.
The broadcast receiver according to the present embodiment is an in-vehicle broadcast receiver that receives DAB (Digital Audio Broadcasting).
As illustrated, the broadcast receiver includes an antenna 11, a front end unit 12, a demodulation unit 13, a channel decoder 14, an audio decoder 15, an output processing unit 16, a control unit 17, an audio output device 18 including an amplifier, a speaker, and the like. A display device 19 and an input device 20.

  The front end unit receives a frequency channel set as a reception channel from the control unit 17 and outputs a reception signal to the demodulation unit 13. The front end unit 12 receives reception signal strength, C / N (Carrier to Noise Ratio), the degree of multipath failure, adjacent noise level, etc. of the current reception channel. Monitoring of the radio wave environment and notification to the control unit 17 of good / bad reception radio wave environment are continuously performed.

The demodulator 13 performs demodulation processing such as OFDM demodulation on the input received signal to restore the received data, and outputs it to the channel decoder 14.
The channel decoder 14 reconstructs a DAB transmission frame from the received data input from the demodulator 13.
Here, FIG. 2 shows the structure of a DAB transmission frame.
As shown in the figure, a DAB transmission frame is composed of synchronization SC (Synchronization Channel), FIC (Fast Information Channel), and MSC (Main Service Channel) blocks.

The SC is composed of NULL for coarse synchronization and PRS for phase synchronization.
In addition, the FIC transmits information related to broadcasting services such as information necessary for the receiver to select a program and auxiliary information for the program.
The MSC includes a plurality of subchannels, and each subchannel transmits broadcast content data such as audio data.
Returning to FIG. 1, when the channel decoder 14 reconstructs such a transmission frame, the FIC in the transmission frame is generated in the decoding process such as Viterbi decoding of the FIC data or the FIC data. The error rate detection process of the detected error is performed and the decoded FIC data is sent to the control unit 17 and the error rate of the detected FIC data is notified to the control unit 17.

  Further, the channel decoder 14 performs decoding processing such as Viterbi decoding of subchannel data on subchannel audio data designated as a reception subchannel from the MSC control unit 17 of the reconfigured transmission frame, Error rate detection processing for errors occurring in the data is performed, the decoded sub-channel audio data is sent to the audio decoder 15, and the detected error rate of the sub-channel data is notified to the control unit 17.

The audio decoder 15 decodes the audio data sent from the channel decoder 14 and outputs it to the audio output device 18 via the output processing unit 16.
Then, the control unit 17 sets a reception channel in the front end unit 12 according to the user's channel selection operation received via the input device 20 and the FIC data sent from the channel decoder 14, Processing such as setting a reception subchannel in the decoder 14 is performed.

  Further, the control unit 17 displays an appropriate operation screen on the display device 19 via the output processing unit 16, and displays program information included in the FIC data on the display device 19 via the output processing unit 16. Processing is also performed.

Hereinafter, output mute processing performed by the control unit 17 in such a broadcast receiver will be described.
When the control unit 17 is instructed by the user to start receiving broadcasts, the control unit 17 causes the output processing unit 16 to start outputting audio data input from the audio decoder 15 to the audio output device 18 and performs output mute processing. Start.

FIG. 3 shows the procedure of output mute processing.
As shown in the figure, in this output mute process, the control unit 17 waits for notification of the error rate of the FIC data from the channel decoder 14 (step 302), and if notified, the notified error rate is a predetermined error rate. It is checked whether or not the threshold Th1 is exceeded (step 304).

If the error rate of the FIC data is not equal to or greater than the threshold value Th1 (step 304), the process returns to step 302 to wait for notification of the error rate of the next FIC data.
On the other hand, if the error rate of the FIC data is equal to or higher than the threshold value Th1 (step 304), it is checked whether or not the reception radio wave environment currently notified from the front end unit 12 is bad (step 306). If there is, the output processing unit 16 stops the output of the audio data to the audio output device 18 to mute the audio output (step 312), and the process proceeds to step 314.

  On the other hand, if the reception radio wave environment is good (step 306), it waits for notification of the error rate of the subchannel data from the channel decoder 14 (step 308). If notified, the notified error rate is a predetermined error rate. It is checked whether or not the threshold value is Th2 or more (step 310).

If the error rate of the subchannel data is not equal to or higher than the threshold value Th2 (step 310), the process returns to step 302 to wait for notification of the error rate of the next FIC data.
On the other hand, if the error rate of the sub-channel data is equal to or higher than the threshold value Th2 (step 310), the audio output is muted (step 312), and the process proceeds to step 314.
Then, the audio output is muted as described above (step 312), and if the process proceeds to step 314, the notification of the error rate of the FIC data from the channel decoder 14 is waited. If notified, the notified error is notified. It is checked whether the rate is less than a predetermined threshold value Th1 (step 316). If not less than the threshold value, the process returns to step 314 to wait for notification of the error rate of the next FIC data.

  On the other hand, if the error rate of the FIC data is less than the threshold Th1 (step 316), the notification of the error rate of the subchannel data from the channel decoder 14 is waited (step 318). It is checked whether the error rate is less than a predetermined threshold value Th2 (step 320).

If the error rate of the subchannel data is not less than the threshold value Th2 (step 320), the process returns to step 314 to wait for notification of the error rate of the next FIC data.
On the other hand, if the error rate of the subchannel data is less than the threshold value Th2 (step 320), the output processing unit 16 resumes outputting the audio data to the audio output device 18, thereby canceling the mute of the audio output. Then (step 322), the process returns from step 302.

The output mute process performed by the control unit 17 has been described above.
In the above mute processing, the mute is canceled when both the error rate of the FIC data and the error rate of the sub-channel data are good. However, this is because the reception radio wave environment is good. If the error rate of the FIC data is good, the mute may be canceled. Alternatively, if the reception radio wave environment is good and the sub-channel data error rate is good, the mute may be canceled.

Hereinafter, an example of such output mute processing will be described.
Now, the error rate of the FIC data of the received transmission frame is a faulty error rate that is greater than or equal to the threshold Th1, and the error rate of the reception subchannel of the MSC of the received transmission frame is that of the threshold Th2 or more Assume that the error rate.

  In this case, as shown in FIG. 4a, when the reception radio wave environment monitored by the front end unit 12 is good, the FIC of the transmission frame is received, and the channel decoder 14 decodes the FIC data and exceeds the threshold Th1. When the error rate is detected, the audio output is not muted, and then the MSC of the transmission frame is received. The channel decoder 14 decodes the received subchannel data and exceeds the threshold Th2. The audio output is muted at the time when the error rate is detected.

  On the other hand, as shown in FIG. 4b, when the reception radio wave environment monitored by the front end unit 12 is poor, the FIC of the transmission frame is received, and the channel decoder 14 decodes the FIC data and exceeds the threshold Th1. When a defective error rate is detected, the audio output is immediately muted.

  Here, when the error rate of the FIC data is a bad error rate equal to or higher than the threshold value Th1 and the reception radio wave environment is bad, the bad error rate of the FIC data is bad for the reception radio wave environment. In this case, since the influence of the reception radio wave environment is equally applied to the reception subchannel, the error rate of the reception subchannel is also a bad error rate equal to or higher than the threshold value Th2.

  Therefore, when the reception radio wave environment is poor in this way, even if the mute is started only according to the error rate of the FIC data, it is not possible although the error rate of the subchannel is good. There is a high probability that it will not be properly muted.

Therefore, even if the mute is started only in accordance with the error rate of the FIC data, the audio output can be appropriately muted.
Further, according to the output mute processing of the present embodiment, when the reception radio wave environment is poor, compared to when the reception radio wave environment is good, the time T1 from the transmission frame reception to the start of mute in FIGS. If T2 is used, mute of audio output can be started immediately for T2-T1 time.

  DESCRIPTION OF SYMBOLS 11 ... Antenna, 12 ... Front end part, 13 ... Demodulation part, 14 ... Channel decoder, 15 ... Audio decoder, 16 ... Output processing part, 17 ... Control part, 18 ... Audio | voice output apparatus, 19 ... Display apparatus, 20 ... Input apparatus.

Claims (4)

In each frequency channel, a broadcast that transmits a transmission frame including information data representing information related to a broadcast service and audio data of a program provided by the broadcast service in that order is received, and audio represented by the audio data is received. A broadcast receiver that outputs audio,
Radio wave environment detection means for detecting good / bad reception radio wave environment of the receiving frequency channel,
Information data error rate detection means for detecting good / bad error rate of the information data of the received transmission frame;
Audio data error rate detection means for detecting good / bad error rate of the audio data of the received transmission frame;
Audio output mute control means for muting the audio output,
The audio output mute control means includes
When the radio wave environment detection unit detects a defect in the reception radio wave environment, when the information data error rate detection unit detects a defect in the error rate of the information data, the audio output is muted.
When the radio wave environment detection means detects a good reception radio wave environment, the information data error rate detection means detects a failure of the error rate of the information data of the transmission frame, and an audio data error rate detection A broadcast receiver characterized in that the audio output is muted when means detects a defect in the error rate of the audio data of the transmission frame. The broadcast receiver according to claim 1,
When the audio output is muted, the audio output mute control means detects that the error rate of the information data in the transmission frame is good, and the audio data error rate detection means A broadcast receiver, wherein the mute of the audio output is canceled when a good error rate of the audio data of the transmission frame is detected. The broadcast receiver according to claim 1 or 2,
The broadcast is a broadcast by DAB (Digital Audio Broadcasting),
The information data is data transmitted using FIC (Fast Information Channel) of a DAB transmission frame,
The broadcast receiver, wherein the audio data is audio data transmitted using a subchannel (Sub Channel) to be received of an MSC (Main Service Channel) of a DAB transmission frame. In each frequency channel, a broadcast that transmits a transmission frame including information data representing information related to a broadcast service and audio data of a program provided by the broadcast service in that order is received, and audio represented by the audio data is received. In a broadcast receiver for audio output, a mute control method for controlling mute of the audio output,
A radio wave environment detecting step in which the broadcast receiver detects whether the received radio wave environment of the frequency channel being received is good or bad;
An information data error rate detection step in which the broadcast receiver detects good / bad error rate of the information data of the received transmission frame;
An audio data error rate detection step in which the broadcast receiver detects good / bad error rate of the audio data of the received transmission frame;
The broadcast receiver has a mute step for muting the audio output;
The mute step includes
If a reception radio wave environment failure is detected in the radio wave environment detection step, the audio output is muted when an error rate of the information data is detected in the information data error rate detection step,
When the reception radio wave environment is detected to be good in the radio wave environment detection step, an error rate of the information data in the transmission frame is detected in the information data error rate detection step, and an audio data error rate detection is performed. A mute control method comprising: a step of muting the audio output when an error rate defect of the audio data of the transmission frame is detected in the step.