Broadcast receiver

Abstract

 A DAB receiver a first tuner (10) that receives a broadcast program, and a second tuner (20) that selectively performs searching operation including searching for a receivable radio station and data service receiving operation including receiving EPG data of the radio station. The DAB receiver also includes a searching unit (42) that performs the searching operation, a search result storage unit (44) that stores therein a search result each time the searching unit (42) performs the searching operation, and an operation ratio setting unit (48) that compares between a latest search result acquired by the searching unit (42) and the search result stored in the search result storage unit (44) and, in the case where there has been a change of the receivable radio station, increases a ratio of the searching operation and decreases a ratio of the data service receiving operation.

Description

[0001] The present invention relates to a broadcast receiver configured to receive program data, particularly made in compliance with digital audio broadcasting (DAB) standard.

[0002] A radio data system has thus far been know that includes a reception unit for receiving radio station information and traffic information, and is configured to monitor radio wave environment by scanning field intensity, and to perform frequency scanning upon deciding that the radio wave environment is abnormal, to thereby update a list of receivable radio stations (station list) according to the radio station information received by the reception unit, for example as disclosed in JP 2011-19041 A.

[0003] With the system according to the cited document, the field intensity has to be scanned in order to decide whether the radio station list is updated, which is a complicated processing. In addition, the timing to update the radio station list is changed depending on the radio wave environment, by which the timing to receive TMC, which is another RDS data, is also changed, however the time for receiving the RDS data remains unchanged and therefore such another RDS data is unable to be efficiently received.

[0004] The present invention provides a broadcast receiver capable of quickly updating the radio station list when necessary without additionally performing a complicated processing, and efficiently receiving data service utilizing the interim between updating operations of the radio station list.

[0005] The invention is related to a broadcast receiver according to claim 1. Embodiments are disclosed in the dependent claims.

[0006] In an aspect, the present invention provides a broadcast receiver including a first tuner that receives a broadcast program, and a second tuner that selectively performs searching operation including searching for a receivable radio station and data service receiving operation including receiving data service of the radio station. The broadcast receiver also includes a searching unit that performs the searching operation, a search result storage unit that stores therein a search result each time the searching unit performs the searching operation, and an operation ratio setting unit that compares between a latest search result provided from the searching unit and the search result stored in the search result storage unit and, in the case where there has been a change of the receivable radio station, increases a ratio of the searching operation and decreases a ratio of the data service receiving operation.

[0007] The broadcast receiver with means configured as above can decide whether there has been a change of the receivable radio station by comparing the results of the searching operations repeatedly performed, and increase the ratio of the searching operation in the case where there has been a change. Therefore, the searching operation can be quickly performed when necessary so as to update the radio station list, without the need to additionally perform a complicated operation such as field intensity scanning.

[0008] Preferably, the operation ratio setting unit may be configured to decrease the ratio of the searching operation and to increase the ratio of the data service receiving operation in the case where there has been no change of the receivable radio station through comparison between the latest search result provided by the searching unit and the search result stored in the search result storage unit. Increasing thus the ratio of the data service receiving operation in the case where there has been no change of the receivable radio station enables efficient reception of the data service utilizing the interim between the searching operations (generation of radio station list).

[0009] Preferably, the operation ratio setting unit may be configured to decide whether there has been a change of the receivable radio station on the basis of the number of receivable radio stations. Such an arrangement makes it possible to confirm whether there has been a change of the receivable radio station, simply by comparing the number of radio stations.

[0010] To perform the searching operation with respect to the receiving frequency band, a predetermined period of time is required. Accordingly, it is preferable that, in the case where there has been no change of the receivable radio station, the operation ratio setting unit is configured to maintain a time period required for performing the searching operation, and to prolong a time period for performing the data service receiving operation with respect to a time period set in the case where there has been a change of the receivable radio station. Such an arrangement enables efficient reception of the data service utilizing the interim between the searching operations.

[0011] Preferably, the operation ratio setting unit may be configured to maintain the time period required for performing the searching operation, and to continuously repeat the searching operation which requires the same time period, in the case where there has been a change of the receivable radio station. Such an arrangement enables the searching operation to be performed in a shortest possible time and assures that a latest radio station list is obtained.

[0012] Preferably, the data service receiving operation may include acquiring at least one of electronic program guide data and transport protocol experts group (TPEG) data. Such an arrangement enables the radio station list to be quickly updated in the case where there has been a change of the receivable radio station, and allows the electronic program guide data and TPEG to be efficiently and quickly received, in the case where there has been no change of the receivable radio station.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] 

Fig. 1 is a block diagram showing a configuration of a DAB receiver according to an embodiment;

Fig. 2 is a schematic diagram showing a frame structure of an exemplary DAB broadcasting signal;

Fig. 3 is a flowchart showing an embodiment of a procedure for varying the ratio of searching operation and data service receiving operation according to a search result of a receivable radio station; and

Figs. 4A to 4C are schematic exemplary diagrams for explaining relationship between a change in number of radio stations and EPG data receiving operation.

[0014] Hereafter, an embodiment of a digital audio broadcasting (DAB) receiver, exemplifying the broadcast receiver according to the present invention, will be described with reference to the drawings. Fig. 1 is a block diagram showing a configuration of the DAB receiver according to the embodiment. As shown in Fig. 1, the DAB receiver according to this embodiment includes a first tuner 10, a second tuner 20, a decoder 30, an output processing unit 32, an amplifier 34, a speaker 36, a control unit 40, a display unit 50, and an operation unit 52. The DAB receiver is mounted in a vehicle.

[0015] The first tuner 10 serves to receive a broadcast program. To be more detailed, the first tuner 10 and the decoder 30 receive a digital broadcasting signal (DAB broadcasting signal) modulated by orthogonal frequency division multiplexing (OFDM), and reproduce sound data through demodulation and decoding. The first tuner 10 includes, for example, a front end (F/E)12, and an analog/digital (A/D) converter 14. The F/E 12 converts the broadcasting signal received via an antenna 16 into an intermediate frequency signal. The A/D converter 14 converts the intermediate frequency signal, which is an analog signal, to digital data (intermediate frequency data). The decoder 30 demodulates and decodes the intermediate frequency data so as to generate sound data corresponding to each service.

[0016] Although the decoder 30 demodulates and decodes the intermediate frequency data after the A/D converter 14 converts the intermediate frequency signal outputted from the F/E 12 into the digital data in this embodiment, the transition from the analog process to the digital process may be modified as desired.

[0017] Fig. 2 is a schematic diagram showing a frame structure of the DAB broadcasting signal. As shown in Fig. 2, the frame of the DAB broadcasting signal is composed of a synchronization channel, a first information channel FIC, and a main service channel MSC.

[0018] The synchronization channel is composed of a NULL symbol and a phase reference symbol (PRS), and is utilized to synchronize the frames by detecting the head of the frame. The first information channel FIC is a region that describes the content of the main service channel MSC, and includes time/date data, service (program) arrangement data, label (name) of the service, and a service identification code (SID). A plurality of first information groups (FIG) are energy-dispersed into a single first information block (FIB), constituting a predetermined information unit. Each FIB is converted into a convolutional code, and three FIBs turned into the convolutional code constitute one FIC. The main service channel MSC mainly includes music data corresponding to each of the plurality of services. The main service channel MSC includes a plurality of sub channels (SubCh) that are energy-dispersed, converted into a convolutional code, and time-interleaved.

[0019] The output processing unit 32 receives the sound data outputted from the decoder 30, and performs variable control of the sound volume and superposing of other sounds (for example, operating tone). The amplifier 34 amplifies the sound data outputted from the output processing unit 32 and outputs the amplified sound through the speaker 36. Here, actually it is necessary to convert the sound data subjected to the processing in the output processing unit 32 into analog sound data. Such conversion may be performed in the output processing unit 32, or in a digital/analog converter provided posterior to the output processing unit 32.

[0020] The second tuner 20 serves to receive the DAB signal, to perform the searching operation including searching for the receivable radio station and the data service receiving operation including receiving the data service from the radio station. The second tuner 20 includes a front end (F/E) 22 and an A/D converter 24, as does the first tuner 10. The F/E 22 converts a broadcasting signal received via the antenna 16 into an intermediate frequency signal. The A/D converter 24 converts the intermediate frequency signal, which is an analog signal, to digital data (intermediate frequency data).

[0021] The control unit 40 controls the receiving operation of the DAB receiver as a whole and also performs the searching operation and the data service receiving operation. Accordingly, the control unit 40 includes a searching unit 42, a search result storage unit 44, an EPG processing unit 46, and an operation ratio setting unit 48. Here, components related to ordinary receiving operation, such as selection of the service (program) or display of the content of the service being received, are excluded from Fig. 1.

[0022] The searching unit 42 sweeps a receiving frequency band in a predetermined direction, to thereby detect a plurality of ensembles contained in the receiving frequency band and generate a list of the radio stations corresponding to the respective ensembles. The search result storage unit 44 stores therein a search result (radio station list) provided from the searching unit 42. The EPG processing unit 46 reviews the content of the plurality of ensembles contained in the receiving frequency band and generates an electronic program guide (EPG) including the list of the services (programs) contained in each of the ensembles. In this embodiment, EPG data receiving operation is performed as an example of the data service receiving operation, to generate the EPG with the EPG processing unit 46 on the basis of the received EPG data.

[0023] The operation ratio setting unit 48 compares between the latest search result provided from the searching unit 42 and the search result stored in the search result storage unit 44, and increases the ratio of the searching operation and decreases the ratio of the data service receiving operation, in the case where there has been a change of the receivable radio station. In addition, the operation ratio setting unit 48 compares between the latest search result provided from the searching unit 42 and the search result stored in the search result storage unit 44, and decreases the ratio of the searching operation and increases the ratio of the data service receiving operation, in the case where there has been no change of the receivable radio station. Here, the operation ratio setting unit 48 decides whether there has been a change of the receivable radio station on the basis of the number of receivable radio stations.

[0024] An operation of the DAB receiver according to this embodiment will now be described hereunder. Fig. 3 is a flowchart showing a procedure for varying the ratio of the searching operation and the data service receiving operation according to the search result of the receivable radio station.

[0025] The searching unit 42 decides whether it is a timing to perform the searching operation (step 100). In this embodiment, for example, it is assumed that the searching operation by the searching unit 42 and the EPG data receiving operation by the EPG processing unit 46 are generally alternately performed, and the timing to start the next searching operation is known at least at the time of the EPG data receiving operation or at the time of the searching operation.

[0026] In the case where it is not yet the timing for the searching operation, a negative decision is made at step 100, and the same decision is repeated. When the timing for the searching operation is reached an affirmative decision is made at step 100, and the searching unit 42 performs the searching operation (step 102). After the searching operation is finished (or in parallel with the searching operation), the search result storage unit 44 stores the result of the searching operation (step 104).

[0027] Then the operation ratio setting unit 48 compares between the search result provided this time from the searching unit 42 and the search result stored in the search result storage unit 44, and decides whether there has been a change of the receivable radio station, more specifically the number of receivable radio stations (step 106). In the case where the number of radio stations remain unchanged, for example because of stable reception quality (radio wave condition), a negative decision is made. In this case, the operation ratio setting unit 48 prolongs the next time period to acquire the EPG data (time period for the next EPG data receiving operation), while maintaining the time required for the searching operation (step 108). The operation ratio setting unit 48 decreases the ratio of the searching operation and increases the ratio of the EPG data receiving operation, by instructing such settings to the searching unit 42 and the EPG processing unit 46.

[0028] In the case where the number of radio stations has changed, for example because of fluctuation in reception quality (radio wave condition) originating from the running condition of the vehicle, an affirmative decision is made at step 106. Then the operation ratio setting unit 48 decides whether the number of radio stations has changed by 1 (step 110). In the case where the number has changed by 1 (i.e., when the change in number of radio stations is small), an affirmative decision is made. In this case, the operation ratio setting unit 48 shortens the next time period to acquire the EPG data (time period for the next EPG data receiving operation), while maintaining the time required for the searching operation (step 112). The operation ratio setting unit 48 increases the ratio of the searching operation and decreases the ratio of the EPG data receiving operation, by instructing such settings to the searching unit 42 and the EPG processing unit 46.

[0029] In the case where the number of radio stations has changed by 2 or more (change in number of radio stations is large), a negative decision is made at step 110. In this case, the operation ratio setting unit 48 instructs the searching unit 42 to maintain the time required for the searching operation and continuously repeat the searching operation instead of the next EPG data receiving operation (step 114). Then the procedure returns to step 102 and the searching operation is immediately performed.

[0030] Although the flowchart referred to above does not include the process of the EPG data receiving operation, it may be understood that the EPG data receiving operation is performed after the searching operation of step 102 is finished and before the timing for the next searching operation is reached.

[0031] Figs. 4A to 4C are schematic diagrams for explaining relationship between the change in number of radio stations and the EPG data receiving operation. In Figs. 4A to 4C, "SEARCH" represents the timing to perform the searching operation and "EPG" represents the timing to perform the EPG data receiving operation. "T0" represents the time period required for performing the searching operation, for which a predetermined time is secured each time. "T10" and "T11" each represent a time period allocated for performing the EPG data receiving operation.

[0032] As shown in Fig. 4A, in the case where the number of radio stations has not changed in comparison between the search result of last time and the search result of this time, the time T10 allocated for the EPG data receiving operation to be performed after the searching operation of this time is equal to the time T10 for the EPG data receiving operation of last time, which is longer than the time T11 (Fig. 4B) set in the case where the number of radio stations has changed.

[0033] Referring to Fig. 4B, in the case where the number of radio stations has changed by 1 in comparison between the search result of last time and the search result of this time, the time T11 allocated for the EPG data receiving operation to be performed after the searching operation of this time is made shorter than the time T10 for the EPG data receiving operation of last time, or shorter than the time T10 (Fig. 4A) set in the case where the number of radio stations has not changed.

[0034] Referring further to Fig. 4C, in the case where the number of radio stations has changed by 2 or more in comparison between the search result of last time and the search result of this time, the EPG data receiving operation supposed to be performed after the searching operation of this time is cancelled, and instead the searching operation of next time is continuously performed.

[0035] As described above, the DAB receiver according to this embodiment decides whether there has been a change of the receivable radio station by comparing the results of the searching operations repeatedly performed, and increases the ratio of the searching operation in the case where there has been a change. Therefore, the searching operation can be quickly performed when necessary so as to update the radio station list, without the need to additionally perform a complicated operation such as field intensity scanning.

[0036] In addition, in the case where there has been no change of the receivable radio station, the ratio of the EPG data receiving operation is increased, and therefore the EPG data can be efficiently received utilizing the interim between the searching operations (generation of radio station list).

[0037] In particular, the operation ratio setting unit 48 decides whether there has been a change of the receivable radio station on the basis of the number of receivable radio stations. Such an arrangement makes it possible to confirm whether there has been a change of the receivable radio station, simply by comparing the number of radio stations.

[0038] Further, since a predetermined period of time T0 is required for performing the searching operation with respect to the receiving frequency band, in the case where there has been no change of the receivable radio station, the operation ratio setting unit 48 maintains the time T0 required for the searching operation, and prolongs the time T10 for performing the data service receiving operation with respect to the time T11 set in the case where there has been a change of the receivable radio station. Such an arrangement enables efficient reception of the EPG data utilizing the interim between the searching operations.

[0039] Further, the operation ratio setting unit 48 instructs the searching unit 42 to maintain the time T0 required for the searching operation, and to continuously repeat the searching operation which requires the time T0, in the case where there has been a change of the receivable radio station. Such an arrangement enables the searching operation to be performed in a shortest possible time and assures that the latest radio station list is obtained.

[0040] The present invention is in no way limited to the foregoing embodiment, but may be modified in various manners within the scope of the present invention. Although the data service of the radio station is exemplified by provision of the EPG data that enables generation of the EPG in the foregoing embodiment, the EPG data may be substituted with another type of data, or the EPG data and the another data service may be alternately processed. For example, the DAB receiver may be configured to receive TPEG data and display the content thereof. Such an operation may be performed in parallel or alternately with the reception of the EPG data.

[0041] Further, although the first tuner 10 is employed for receiving the broadcast program and the second tuner 20 is employed for the searching operation and the reception of the data service in the foregoing embodiment, a decoder may also be provided posterior to the second tuner 20, so as to independently receive broadcast programs by two systems, or perform diversity reception. For the diversity reception, it is preferable to provide the antenna 16 for each of the first tuner 10 and the second tuner 20.

[0042] As described above, the DAB receiver according to the present invention decides whether there has been a change of the receivable radio station by comparing the results of the searching operations repeatedly performed, and increases the ratio of the searching operation in the case where there has been a change. Therefore, the searching operation can be quickly performed when necessary so as to update the radio station list, without the need to additionally perform a complicated operation such as field intensity scanning.

Claims

1. A broadcast receiver including a first tuner (10) that is configured to receive a broadcast program, and a second tuner (20) that is configured to selectively perform searching operation including searching for a receivable radio station and data service receiving operation including receiving data service of the radio station, the broadcast receiver comprising:

a searching unit (42) that is configured to perform the searching operation;

a search result storage unit (44) that is configured to store therein a search result each time the searching unit (42) performs the searching operation; and

an operation ratio setting unit (48) that is configured to compare between a latest search result provided from the searching unit (42) and the search result stored in the search result storage unit (44) and, in the case where there has been a change of the receivable radio station, to increase a ratio of the searching operation and to decrease a ratio of the data service receiving operation.

2. The broadcast receiver according to Claim 1,
wherein the operation ratio setting unit (48) is configured to compare between the latest search result provided from the searching unit (42) and the search result stored in the search result storage unit (44), and to decrease the ratio of the searching operation and to increase the ratio of the data service receiving operation in the case where there has been no change of the receivable radio station.

3. The broadcast receiver according to Claim 1 or 2,
wherein the operation ratio setting unit (48) is configured to decide whether there has been a change of the receivable radio station on the basis of the number of receivable radio stations.

4. The broadcast receiver according to any one of Claims 1 to 3,
wherein, in the case where there has been no change of the receivable radio station, the operation ratio setting unit (48) is configured to maintain a time period required for performing the searching operation, and to prolong a time period for performing the data service receiving operation with respect to a time period set in the case where there has been a change of the receivable radio station.

5. The broadcast receiver according to any one of Claims 1 to 4,
wherein the operation ratio setting unit (48) is configured to maintain the time period required for performing the searching operation, and to continuously repeat the searching operation which requires the same time period, in the case where there has been a change of the receivable radio station.

6. The broadcast receiver according to any one of Claims 1 to 5,
wherein the data service receiving operation includes acquiring at least one of electronic program guide data and TPEG data.

Drawing