JPH11234154A - Multiplex broadcast receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce sound skip and the temporary overlap of sound and to provide easily audible output sound. SOLUTION: A DAB(digital audio broadcast) receiver 1 is provided with a DAB front end part 4, a DAB decoding part 6, an audio decoding part 8, an FM/AM front end part 18, an FM/AM demodulation part 20, an RDS(radio data system) decoding part 22, a control part 24 and a switch part 26. The control part 24 outputs the sound of the service of excellent reception quality in the case that the service of the same contents as the service of DAB during reception is broadcasted by an RDS as well, however, right after the reception quality of the DAB is deteriorated and the service to be sound outputted is switched from the DAB to the RDS, even when the reception quality of the RDS is also deteriorated and the reception quality of the DAB is restored, changeover from the RDS to the DAB is not performed again until a prescribed time elapses.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multiplex broadcast receiver capable of receiving both digital audio broadcasts and radio data system broadcasts.

[0002]

2. Description of the Related Art Today, digital audio is generally recognized for its excellent characteristics and ease of use, and is rapidly spreading. Against this background, digitalization of audio broadcasting has become active, and digital audio broadcasting DAB (Digital Audio Broadcasting) has been put to practical use in Europe.

[0003] Such a DAB receiver (DAB receiver) has a considerably complicated configuration as compared with a normal VHF / FM receiver, but has many advantages that can be compensated for. For example, in a moving car, sound quality comparable to a CD can be secured, many broadcast programs can be received, programs can be broadcast in multiple languages, weather and traffic information can be received continuously, and audio and video advertisements can be received. There are advantages such as.

[0004] Currently, each broadcast channel of DAB uses a vacant frequency between reception frequencies allocated to each channel of television broadcasting, and a total of 64 channels are prepared. A carrier frequency group corresponding to each broadcast channel is called an ensemble, and a plurality of broadcast programs (services) are multiplexed on each ensemble.

[0005] Some DAB programs include radio data system broadcasting RDS (Radio Data System) and FM / A.
Some programs are duplicated with M broadcast programs. Therefore, R
In a conventional DAB receiver that can also receive DS, etc., D
When the content of the program of AB and the content of the program such as RDS are the same, the reception quality (reception state) of DAB and the reception quality of RDS and the like are compared, and a program with good reception quality is selected and sound is output. Output.

[0006]

As described above, in the conventional DAB receiver, the reception quality of the DAB is compared with the reception quality of the RDS or the like, and the program is switched to a program having a good reception quality. In the case where the reception quality is close and unstable, the program to be output as audio may be frequently switched.

[0007] Normally, when a program to be output as audio is switched, sound interruption occurs even when the same content is being broadcast. In addition, when DAB is received, it takes time to demodulate and correct errors in digital data inside the DAB receiver. Therefore, when switching from RDS to DAB, sound skipping occurs, and conversely, switching from DAB to RDS. In such a case, a phenomenon such as overlapping sounds occurs. For this reason,
When the program to be output as audio is frequently switched, the output audio becomes difficult to hear, giving the listener discomfort.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to reduce the number of skips and temporary duplication of sounds and to provide a multiplex broadcast reception capable of obtaining an output sound that is easy to hear. To provide machines.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a multiplex broadcast receiver of the present invention receives programs of the same contents broadcast simultaneously by first and second receiving means, respectively. When the output program selecting means selectively outputs a signal having a better reception condition, the program switching operation is restricted again within a predetermined time immediately after switching the program to be output, so that audio output or the like is performed. Can be prevented from switching frequently, and skipping and temporary duplication of audio can be reduced, so that an output sound or the like that is easy to hear can be obtained.

[0010] In addition, as a program in which programs having the same contents are simultaneously broadcast, a case is considered in which digital audio broadcasting and at least one of radio data system broadcasting, AM broadcasting, and FM broadcasting are combined. In general, digital audio broadcasting requires more processing to obtain an audio output than other broadcasting modes, so that each broadcasting station simultaneously outputs the same program in digital audio broadcasting and other broadcasting. Even in this case, the timing at which the program contents are output as audio may be slightly shifted. Therefore, when selectively outputting a digital audio broadcast program and another broadcast program, restricting the switching operation to prevent frequent switching operations is particularly effective for obtaining a sound output that is easy to hear. It is.

It is preferable that the above-described restriction on the program switching operation is performed when the digital audio broadcast program is switched to another broadcast program. By restricting the subsequent program switching operation when switching to one of the programs, it is possible to prevent the program whose contents are output from being frequently switched in a short time.

[0012] Further, even when the switching operation of the program after switching from the digital audio broadcast program to the other broadcast program is restricted in this manner, the good reception state of the digital audio broadcast is restored. In this case, it is preferable to switch to a digital audio broadcast program again without performing the limiting operation. In general, digital audio broadcasts have better audio quality than other broadcasts. Therefore, by receiving the digital audio broadcasts preferentially, it is possible to obtain output audio that is easier to hear.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a DAB receiver according to an embodiment to which a multiplex broadcast receiver according to the present invention is applied, a program having the same contents as DAB is broadcast in RDS, and reception quality (reception state)
When switching the broadcast to be output according to the
It is characterized in that by limiting the switching operation, it is possible to prevent the broadcast to be frequently output from being switched. Hereinafter, DA of an embodiment to which the present invention is applied will be described.
The B receiver will be described with reference to the drawings.

FIG. 1 is a diagram showing a D according to an embodiment of the present invention.
It is a figure showing the composition of AB receiver. The DAB receiver 1 shown in FIG. 1 includes a DAB antenna 2, a DAB front end unit (DAB F / E) 4, a DAB decoding unit 6, an audio decoding unit 8, a digital-analog converter (D / A converter) 10, Amplifier 12, speaker 14, FM / AM antenna 16, FM / AM front end (FM / AM)
F / E) 18, FM / AM demodulation unit 20, RDS decoding unit 22, control unit 24, switch unit 26, operation unit 28,
It is configured to include the display unit 30.

The DAB front-end unit 4 extracts a desired reception frequency (tuning frequency) component from the signal received via the DAB antenna 2, and converts an intermediate frequency obtained by performing frequency conversion on the extracted signal. Amplify the signal. The DAB front-end unit 4 outputs a received electric field intensity signal obtained by AM-detecting the amplified intermediate frequency signal to the control unit 2.
Output to 4

The DAB decoding section 6 performs quadrature demodulation processing, FFT (Fast Fourier Transform) demodulation processing and decoding processing on the intermediate frequency signal output from the DAB front end section 4, and converts the interleaved transmission data. Demodulated,
Further, after deinterleaving and returning to the original data sequence, an error detection and correction process is performed, and the high-speed information channel FIC and decoded data (MPE) including the service list of each ensemble indicating the symbol position of the multiplexed broadcast program are displayed.
(G audio data).

The audio decoding unit 8 performs a decompression process for restoring the decoded data (MPEG audio data) output from the DAB decoding unit 6, and outputs decompressed PCM audio data. The D / A converter 10 converts PCM audio data output from the audio decoding unit 8 into an analog signal and outputs the analog signal. Amplifier 12
Amplifies an analog audio signal output from the D / A converter 10 or an analog audio signal after FM detection or AM detection described later, and the amplified audio signal is output from the speaker 14.

The FM / AM front end unit 18
A desired reception frequency (tuning frequency) component is extracted from a signal received via the AM antenna 16;
An intermediate frequency signal obtained by performing frequency conversion on the extracted signal is amplified. Further, the FM / AM front-end unit 18 outputs a received electric field strength signal obtained by AM-detecting the amplified intermediate frequency signal to the control unit 24.

The FM / AM demodulation unit 20 performs AM detection or FM detection on the intermediate frequency signal output from the FM / AM front end unit 18 and outputs an analog audio signal. Further, the FM / AM demodulation unit 20 outputs F
The FM multiplexed signal multiplexed into the M broadcast is separated and R
The signal is output to the DS decoding unit 22. The RDS decoding unit 22 performs delay detection on the FM multiplexed signal output from the FM / AM demodulation unit 20 to reproduce a bit clock and demodulate a bit data sequence.

The control unit 24 includes a DAB front end unit 4
The entire DAB receiver 1 is controlled by performing frequency tuning control by the FM / AM front-end section 18 and control instructions to the DAB decoding section 6 and the RDS decoding section 22. In addition, the control unit 24 issues an instruction to switch the output sound to the switch unit 26 based on the received electric field strength signal input from the DAB front end unit 4 or the FM / AM front end unit 18.

The switch unit 26 selectively switches the audio signal output from the D / A converter 10 or the FM / AM demodulation unit 20 according to the switching instruction output from the control unit 24 and directs the audio signal to the amplifier 12. Output. Operation unit 28
Is provided with various operation keys for the user to issue a program switching instruction or the like, and sends the operation status of the operation keys by the user to the control unit 24. The display unit 30 displays the name or the like given to the currently received DAB program, and displays the operation status of the operation unit 28 by the user.

The above-described DAB front end unit 4, DA
The B decoding unit 6, the audio decoding unit 8, the D / A converter 10, and the control unit 24 serve as the first receiving means, and include the FM / AM front-end unit 18, the FM / AM demodulation unit 20, the RDS decoding unit 22, and the control unit. 24 corresponds to the second receiving means, the switch unit 26 corresponds to the output program selecting means, and the control unit 24 corresponds to the selection control means and the switching operation restricting means.

FIG. 2 is a diagram showing a mode II frame structure of DAB employed in the DAB receiver 1.
One frame length is 24 ms, a synchronization signal SYNC of 2 symbols and a high-speed information channel FIC of 3 symbols.
And a data field DFL of 72 symbols. The synchronization signal SYNC includes a null symbol and a phase reference symbol P used for recognizing the start point of a frame.
RS.

The high-speed information channel FIC is composed of three high-speed information blocks FIB. The data field DFL is divided into 72 data fields, and a broadcast signal of a predetermined service and announcement is inserted in each data field, so that 6 to 8 services can be received simultaneously from one broadcast wave. Has become. Which service corresponds to which data field is specified by a service list included in the high-speed information channel FIC.

The high-speed information block FIB is composed of a plurality of high-speed information groups FIG. Each high-speed information group FIG includes a FIG header and a FIG data field. The FIG header is composed of "FIG type" indicating the type of data included in the FIG data field, and "length" indicating the byte length of the FIG data field. The first byte of the FIG data field has different contents for each FIG type, and an extension is included in a part thereof.

For example, in the case of a type 0 field,
In the first byte of the FIG data field, a C / N (Current / Next) flag and an OE (Other En
semble) flag, P / D flag, and extension. The contents of the detailed data included in the FIG data field are defined by the FIG type and the extension. Hereinafter, for example, a data field corresponding to the extension 6 of the FIG type 0 field is represented as FIG (0/6).

The area excluding the first byte of the FIG data field contains various data specified by the FIG type and extension. By reading this data, various reception controls can be performed. . For example, FIG. (0/5) shows the language code used, and FIG. (1/0) and FIG. (1/1) show the ensemble names and service names displayed on the display unit 30 during program reception. The corresponding text data is included.

In particular, in the receiving operation in the present embodiment,
FIG (0/6), FIG (0/11), FIG (0 /
The data included in 21) is used. FIG (0/6) relating to the link information is configured to include information for identifying an RDS or the like broadcasting a service having the same content as the DAB service being received. FIG (0/11) relating to the area information includes information for specifying the broadcast area of the DAB being received. Also, FIG (0/21) relating to the reception frequency information is configured to include information of the reception frequency for each broadcast area such as RDS. These FIG (0/6), FIG (0/11),
By analyzing FIG (0/21), it is possible to specify a reception frequency such as an RDS that broadcasts a service having the same contents as the DAB service being received in the same broadcast area.

The DAB receiver 1 of the present embodiment has such a configuration, and the operation will be described next. FIG.
FIG. 5 is a diagram showing an operation procedure when the service (program) for outputting audio is selectively switched between DAB and RDS in the DAB receiver 1 of the present embodiment.

First, the control unit 24 determines whether or not the DAB service is being received (step 100).
If a service is being received, it is determined whether the same service as that service is being broadcast by RDS (step 101). Specifically, the control unit 24 obtains the high-speed information channel FIC from the DAB decoding unit 6, and obtains FIG (0/6) for link information and FI for regional information.
G (0/11), FIG (0 /
By analyzing 21), it is checked whether or not the same service as the DAB service being received is being broadcast by RDS in the same broadcast area. When broadcasting, the reception frequency data is obtained.

If the same service as the DAB service being received is not broadcast by RDS, the switch unit 26
As a result, the state in which the output of the D / A converter 10 is selected is maintained, and the DAB service receiving operation and the sound output operation are continued. If the same service as the DAB service being received is being broadcast by RDS, the control unit 24
Is based on the obtained RDS reception frequency data,
Set the reception frequency of the M / AM front end unit 18,
The reception of the RDS service having the same contents as the DAB service is started (step 102).

When the reception of the RDS service is started in this way, the reception operation of the DAB service and R
Although the receiving operation of the DS service is performed in parallel, the D / A
A state in which the audio signal output from the converter 10 is selected by the switch unit 26, amplified by the amplifier 12, and output from the speaker 14 is continued.

Next, the control unit 24 controls the DAB based on the received electric field strength signals input from the DAB front end unit 4 and the FM / AM front end unit 18, respectively.
It is determined whether the reception quality (reception state) of the RDS is deteriorated and the reception quality of the RDS is good (step 10).
3).

When the reception quality of DAB is good,
If the reception quality of RDS is deteriorated but the reception quality of RDS is also poor, the control unit 24 returns to step 100 and returns to DAB
Each operation after the service reception monitoring operation is repeated. When the reception quality of DAB is deteriorated and the reception quality of RDS is good, the control unit 24
6 and switches the service for voice output from DAB to RDS (step 104).

Next, the control unit 24 determines whether or not a predetermined time (for example, 30 seconds) has elapsed since the service for outputting the audio is switched from DAB to RDS (step 10).
5) After a lapse of a predetermined time, the DAB based on the received electric field strength signal input from the DAB front end unit 4
It is determined whether the reception quality of B is good (step 106). If the reception quality of the DAB is good, the control unit 24 issues an instruction to the switch unit 26 again, and switches the service for voice output from RDS to DAB (step 108).

If the reception quality of the DAB is not good (if a negative determination is made in step 106), the control unit 24 further determines whether or not the reception quality of the RDS is good (step 107). If it is good, the process returns to step 106 to repeat each operation after the operation of determining the DAB reception state. If the reception quality of the RDS is not good, that is, if both the reception quality of the DAB and the reception quality of the RDS are not good, the control unit 24 issues an instruction to the switch unit 26 to change the service for voice output from the RDS to the DA.
Switch to B (step 108). After the service for outputting audio is switched to DAB, the operation after step 100 is repeated.

As described above, the DAB receiver 1 of this embodiment
When the RDS service having the same content as the DAB service being received is being broadcast, the service having the same content is received in parallel, and the reception quality of the RDS is good and the DAB service is received.
When the reception quality of the service decreases, the service for outputting the audio from the DAB to the RDS is switched. In this state, RD
When the reception quality of S is reduced or the reception quality of DAB is restored, the service for outputting audio is switched to the RDS side, and after a predetermined time or more, the service for outputting audio is switched to the DAB side again. ing. Therefore,
When the reception quality of DAB and RDS is close to each other and the reception quality is unstable, it is possible to avoid a situation in which the service for outputting the sound is frequently switched and to reduce the skipping and the temporary duplication of the sound. An easy audio output can be obtained.

In the above-described embodiment, when the service for outputting audio is switched from DAB to RDS,
After a lapse of a predetermined time from the switching point, the RDS
When the reception quality of DAB is reduced or the reception quality of DAB is restored, switching from RDS to DAB is performed. However, when the reception quality of DAB is good, immediately after switching to the DAB side, the switching is performed again. Since switching to the RDS side is considered to be unlikely to occur, the service for outputting audio may be switched to the DAB side even if a predetermined time has not elapsed from the switching point.

FIG. 4 shows a case where the DAB receiver 1 of the present embodiment switches the audio output service from DAB to RDS only when the reception quality of the DAB becomes good, and when a predetermined time elapses. It is a flowchart which shows the operation | movement procedure at the time of switching to a DAB side again without waiting. The operations of Steps 200 to 204 shown in FIG. 4 correspond to the operations of Steps 100 to 104 shown in FIG. 3 and are basically the same, and therefore the following operation procedure will be described.

When the service for voice output is switched to RDS (step 204), the control unit 24 determines whether or not a predetermined time has elapsed after switching to RDS (step 205). If the predetermined time has not elapsed, the control unit 24 determines whether the reception quality of the RDS is degraded and the reception quality of the DAB is good (step 20).
7A).

RDS reception quality deteriorates and DA
If the reception quality of B is good, the control unit 24 issues an instruction to the switch unit 26, and switches the service for voice output from RDS to DAB (step 208). Further, when the reception quality of RDS does not deteriorate, or when the reception quality of RDS deteriorates but the reception quality of DAB also deteriorates,
Returning to step 205, the service for voice output is set to RD
The determination as to whether or not a predetermined time has elapsed after switching to S is continued.

When a predetermined period of time has elapsed since the service for voice output is switched to RDS (when an affirmative determination is made in step 205), the control unit 24 determines whether the DAB reception quality is good. (Step 206) If the broadcast is good, an instruction is issued to the switch unit 26 to switch the broadcast for audio output from RDS to DAB (Step 208). If the DAB reception quality is not good (negative determination in step 206), the control unit 24
Determines further whether or not the reception quality of the RDS is good (step 207).
Returning to step 06, each operation after the operation of determining the reception state of DAB is repeated. If the operation is not good, an instruction is issued to the switch unit 26 to switch the broadcast to be output from RDS to DAB (step 208).

As described above, the service for outputting voice is DA
Even before the lapse of a predetermined time since switching from B to RDS, only when the reception quality of the RDS is deteriorated and the reception quality of the DAB is good, the service for outputting audio is returned to the DAB again. By preferentially outputting audio of a DAB service with good sound quality, it is possible to listen to the broadcast contents in good condition. In particular, since switching to DAB is performed only when the reception quality of DAB is good,
Immediately after switching to DAB, switching from DAB to RDS is unlikely to occur, and it is possible to reduce skipping and temporary duplication of audio due to frequent switching of the audio output service.

In the above-described embodiment, first, DA
B service is being received or not, but it is possible that only the RDS service is being received.
It may be determined whether or not the S service is being received. FIG. 5 is a block diagram of the DAB receiver 1 according to the present embodiment.
FIG. 11 is a diagram illustrating an operation procedure when selectively outputting a voice output service between DAB and RDS when only a DS service is received and voice output is performed.

First, the control unit 24 determines whether or not the RDS service is being received (step 300). If the RDS service is being received, the control unit 24 analyzes the control information of the RDS and determines the same service as the RDS service being received. It is determined whether or not is broadcast on DAB (step 301). If the same service as the RDS service being received is not being broadcast on the DAB, the reception / audio output operation of the RDS service is continued. On the other hand, when the same service as the RDS service being received is being broadcast by DAB, the control unit 24
Sets the reception frequency of the DAB front-end unit 4 to the reception frequency of the DAB broadcasting the same service as the RDS service being received, starts the reception of this DAB service (step 302), and switches An instruction is issued to the unit 26, and the service for outputting sound is switched from RDS to DAB (step 303).

Next, the control unit 24 determines whether the reception quality of the DAB is deteriorated and the reception quality of the RDS is good (step 304). When the reception quality of the DAB is good, or when the reception quality of the DAB is deteriorated but the reception quality of the RDS is also poor, the determination processing of step 304 is repeated. Also, the reception quality of DAB deteriorates,
If the reception quality of the RDS is good, the control unit 24 issues an instruction to the switch unit 26, and switches the service for voice output from DAB to RDS (step 3).
05). Thereafter, it is determined whether or not a predetermined time has elapsed from the switching operation (step 306). After the predetermined time has elapsed, the operation of determining the reception quality of each of DAB and RDS and the operation of switching the service for outputting audio are performed (step 30).
7-309). The operations in steps 307 to 309 correspond to the operations in steps 106 to 108 shown in FIG. 3, and basically the same operations are performed.

As described above, when only the RDS service is being received and the DAB service having the same content as the RDS service is being broadcast, the service for simultaneously receiving the same content and outputting the audio is provided. To DA
When the reception quality of the RDS is good and the reception quality of the DAB is reduced,
The service for outputting voice to S is switched. If the reception quality of the RDS is reduced or the reception quality of the DAB is restored in this state, the service for outputting the audio is switched to the RD.
After switching to the S side, if a predetermined time or more has elapsed, the service for outputting the audio is switched to the DAB side again. Therefore, it is possible to prevent the service for outputting the audio from being frequently switched, and to improve the broadcast content. Listening becomes possible.

The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the present invention. For example, in the above-described DAB receiver 1, in each of the case where the service for outputting audio is switched from RDS to DAB and the case where the service is switched from DAB to RDS, the elapsed time from the switching point is determined.
Only when the predetermined time has elapsed, the service for outputting audio may be switched to the RDS side or the DAB side again.

Also, in the above-described embodiment, a case has been described in which the service for outputting audio is switched between DAB and RDS. However, a service having the same content as the DAB service may be broadcast in FM broadcast or AM broadcast. The present invention can be applied to a case where a service for outputting a voice is switched between DAB and FM or between DAB and AM.

In the above-described embodiment, when determining the reception quality, the DAB front-end unit 4 and the FM
Although the received field strength signal acquired from the AM front end unit 18 is used, the DAB reception quality may be determined based on the rate of occurrence of bit data errors or by taking this into account.

[0051]

As described above, according to the present invention, when a program having a good reception condition is selectively output from a plurality of programs of the same content received simultaneously, the output program is switched. By restricting the re-program switching operation within a predetermined time immediately after, it is possible to prevent frequent switching of programs for which audio output or the like is performed, and to reduce skipping and temporary duplication of audio to reduce listening. It is possible to obtain easily output audio and the like.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a DAB receiver according to an embodiment to which the present invention has been applied.

FIG. 2 is a diagram illustrating a frame structure used in a DAB receiver.

FIG. 3 is a flowchart showing an operation procedure when a service for outputting audio is selectively switched between DAB and RDS.

FIG. 4 is a flowchart showing an operation procedure of a modified example when a service for outputting audio is selectively switched between DAB and RDS.

FIG. 5 is a flowchart showing an operation procedure of another modified example in which a service for outputting audio is selectively switched between DAB and RDS.

[Explanation of symbols]

1 DAB receiver 4 DAB front end section (DAB F / E) 6 DAB decoding section 8 Audio decoding section 18 FM / AM front end section (FM / AM F / E)
E) 20 FM / AM demodulation unit 22 RDS decoding unit 26 Switch unit 28 Operation unit

Claims (5)

[Claims] 1. First and second receiving means for receiving programs of the same content broadcast simultaneously, and selectively outputting the content of the program received by the first and second receiving means. Output program selection means; and selection control means for controlling the output program selection means based on the respective reception states of the first and second reception means so as to select a broadcast program having a good reception state. A switching operation restricting unit for restricting a switching operation of a program again by the output program selecting unit within a predetermined time after a program output from the output program selecting unit is switched. Receiving machine. 2. The multiplex broadcast receiver according to claim 1, wherein said output program selecting means selectively outputs an audio signal of the program received by said first and second receiving means. 3. The digital audio broadcast according to claim 1, wherein the first receiving unit receives a digital audio broadcast, and the second receiving unit receives at least one of a radio data system broadcast, an AM broadcast, and an FM broadcast. A multiplex broadcast receiver, characterized in that: 4. The switching operation restricting unit according to claim 3, wherein the program output from the output program selecting unit under the control of the selection control unit is changed from the program received by the first receiving unit to the second program.
A multiplex broadcast receiver which limits the switching operation of the program again when the program is switched to the program received by the receiving means. 5. The switching operation restricting unit according to claim 3, wherein the program output from the output program selecting unit is received by the second receiving unit from a program received by the first receiving unit. A multiplex broadcast receiver characterized in that if the good reception state of the first receiving means is restored after switching to a program, the switching operation of the program is not restricted again.