JP5964169B2 - Radio receiver - Google Patents

Description

  The present invention relates to a radio receiver such as RDS (Radio Data System).

  Conventionally, AF (alternate frequency) search is started when it is determined that the current reception state is not good, and if there is an adjacent disturbance in the destination channel, it is the same as the automatic bandwidth automatic variable operation during normal reception FM radio receiver having an RDS reception function in which the control is performed so that the bandwidth is varied according to the received electric field strength, and when there is no adjacent interference, the control is fixed to a wider reference bandwidth. Is known (for example, see Patent Document 1). By performing such control, the bit error rate in the weak electric field state can be improved in the AF search.

JP 2009-105729 A

  By the way, in the FM radio receiver disclosed in Patent Document 1, after the AF search operation is started, it is determined whether there is an adjacent disturbance in the destination channel (alternating frequency broadcast station), and the determination result is as follows. Since the variable bandwidth control is performed accordingly, there is a problem that it takes time to decide whether or not to actually switch to the destination channel. In particular, in a radio receiver having a single tuner configuration, it is necessary to temporarily stop reception of a broadcast signal to be output as an audio output and perform an AF search operation. This is not desirable because it may increase the feeling of discomfort and discomfort for the listener. On the other hand, it is conceivable to fix the bandwidth at the time of AF search operation, but if it is fixed to a narrow bandwidth, the presence or absence of adjacent interference can not be known. It will always be excluded from the target, and both will not be able to switch appropriately to alternative frequency broadcast stations.

The present invention was created in view of the above points, and an object of the present invention is to provide a radio receiver capable of performing appropriate switching to a broadcast station of an alternative frequency in a short time.

  In order to solve the above-described problems, a radio receiver according to the present invention receives a broadcast signal on which alternative frequency data including frequency information of a broadcast station that broadcasts the same program as the broadcast signal being received is superimposed. A front end for receiving a broadcast signal and converting it to an intermediate frequency signal, an intermediate frequency signal output from the front end, and a band pass means for passing a component included in a predetermined pass bandwidth; A reception state determination unit that determines a reception state of the broadcast signal, a bandwidth determination unit that determines a pass bandwidth of the band pass unit according to the reception state determined by the reception state determination unit, and a bandwidth determination unit With the set pass band width in the band pass means, the broadcast signal specified by the frequency information indicated by the alternative frequency data is received and the reception state is And a substitute broadcasting station determination means for constant. In particular, the bandwidth determination unit described above sets the pass bandwidth of the band pass unit wider as the reception state determined by the reception state determination unit is better.

  Since the reception status of the alternative frequency broadcast station is determined by setting the pass bandwidth of the band pass means according to the reception status of the broadcast signal being received, the pass bandwidth is determined according to the reception status of each alternative frequency broadcast station The time required for the AF search operation can be shortened as compared with the case where the variable is made variable. In addition, since the AF search operation is performed by variably setting the pass bandwidth of the band passing means according to the broadcast signal reception state during reception, it is possible to perform the AF search operation that eliminates adjacent interference as necessary. Therefore, appropriate switching to an alternative frequency broadcasting station can be performed.

  Further, the above-described reception state determination unit selects a corresponding one from a plurality of reception state levels classified according to the degree, and the bandwidth determination unit sets the reception state level selected by the reception state determination unit. It is desirable to determine the corresponding pass bandwidth. Since reception state determination and pass bandwidth determination can be performed by selecting from a plurality of candidates, it is possible to simplify these determination operations and determination operations, as well as the pass bandwidth setting operation of the band pass means. .

  In addition, when the reception state determined by the alternative broadcast station determination unit is better than the reception state determined by the reception state determination unit described above, it is indicated by the alternative frequency data from the broadcast signal being received. It is desirable to further include switching means for switching to the broadcast signal specified by the frequency information. Thereby, it is possible to switch to a broadcast signal having a better reception state in consideration of the reception state of the broadcast signal being received. For example, when the reception state of the broadcast signal being received is good, switching can be performed only when there is a broadcast signal having an alternative frequency with a better reception state. In addition, when the reception state of the broadcast signal being received is poor, it is possible to search for an alternative frequency broadcast signal by lowering the value of the reception state serving as a reference for switching.

  Further, the above-described alternative frequency data is preferably included in the broadcast signal of the radio data system. Thereby, it is possible to easily obtain alternative frequency data necessary for performing the operation of the present invention.

  The front end described above preferably has a single tuner configuration for receiving one broadcast signal. As a result, when a single tuner configuration that cannot perform background processing is employed, it is possible to quickly switch to an alternative frequency broadcasting station by performing an AF search operation in a short time.

  In addition, it is desirable to further include audio output means for outputting sound corresponding to the broadcast signal being received and for making the output silent when the determination operation by the alternative broadcast station determination means is being performed. Thereby, it is possible to prevent the audio of the programs of these broadcast stations from being output in a fragmentary manner while confirming the reception status of the broadcast stations of the alternative frequency.

  In addition, it is preferable that the reception state determination by the reception state determination unit and the alternative broadcast station determination unit described above is performed according to the signal strength of the intermediate frequency signal, the presence / absence of multipath interference, and the presence / absence of adjacent interference. As a result, it is possible to determine the reception status of the broadcast station of the alternative frequency while narrowing the pass band width of the band passing means and eliminating adjacent interference, and such a broadcast station can be selected as a switching destination. It becomes possible.

  Moreover, it is desirable to mount in the vehicle. It is desirable that the alternative broadcast station determination means performs an operation for determining the reception state of the broadcast station of the alternative frequency when the reception state of the broadcast signal being received deteriorates at a certain time interval. This makes it possible to reliably search for and switch to a broadcast station of an alternative frequency while receiving a broadcast signal whose reception state changes according to the traveling of the vehicle.

It is a figure which shows the structure of the radio receiver of one Embodiment. It is explanatory drawing of the basic baseband coding structure of RDS data. It is a flowchart which shows the operation | movement procedure which changes AF band width of a band pass filter according to the reception state of the broadcast signal in reception, and performs AF check. It is a figure which shows the relationship between the reception condition of the broadcast signal in reception, and the setting content of the bandwidth of the band pass filter at the time of AF check. It is a figure which shows the specific relationship between the receiving state shown in FIG. 4, and a pass bandwidth.

  Hereinafter, a radio receiver according to an embodiment to which the present invention is applied will be described with reference to the drawings. FIG. 1 is a diagram illustrating a configuration of a radio receiver according to an embodiment. The radio receiver shown in FIG. 1 is mounted on a vehicle and receives an RDS broadcast, and includes an antenna 10, a front end (F / E) 12, an intermediate frequency amplifier (IFA) 14, a bandpass filter (BPF). ) 15, a bandwidth setting unit 16, a reception state detection unit 17, a demodulation unit 20, an amplifier 22, a speaker 24, an RS decoder 30, a control unit 40, an AF list storage unit 50, a display unit 60, and an operation unit 62 Has been. This radio receiver has a single tuner configuration for receiving one broadcast signal.

  In RDS broadcasting, 57 kHz, which is the third harmonic of the 19 kHz stereo pilot signal, is used as a subcarrier, and the subcarrier is amplified by a data signal indicating data related to program-related information or traffic information that is filtered and two-phase coded. Radio data (RDS data) is modulated and the amplitude-modulated subcarrier is frequency-modulated to the main carrier and broadcast.

  FIG. 2 is an explanatory diagram of a basic baseband coding structure of RDS data. As shown in FIG. 2, the RDS data is composed of groups of 104 bits as one group, and each group is composed of 4 blocks (A, B, C, D), and each block is a 16-bit information word. (M0 to m15) and 10-bit check words and offset words (C′0 to C′9).

  In block A, program identification data (PI code: Program Identification Code) indicating a network including country name data and program data is arranged. Block B includes traffic information broadcasting station identification data (TP code: Traffic program Identification code) indicating a traffic information broadcasting station that broadcasts a traffic information program, and program content identification data (PTY code: Program) indicating the type of program. Type code) is arranged. In block C, data relating to the frequency of each station in the network station group broadcasting the same program, that is, alternative frequency data (AF data: Alternative Frequency code) is arranged. This alternative frequency data includes the reception frequency of the broadcast station that broadcasts the same program as the broadcast signal being received. In the block D, broadcasting station name data (PS data: Program Service code) such as a broadcasting station name and a network name is arranged.

  The front end 12 extracts a desired broadcast signal from broadcast signals received via the antenna 10 and performs frequency conversion to generate an IF signal (intermediate frequency signal) corresponding to the broadcast wave. Note that the radio receiver of this embodiment has a single tuner configuration, and the front end 12 receives only one broadcast signal. The intermediate frequency amplifier 14 amplifies the IF signal output from the front end 12.

  The band-pass filter 15 performs band limitation on the input IF signal and allows a component having a set pass bandwidth to pass therethrough. The bandwidth setting unit 16 variably sets the pass bandwidth of the bandpass filter 15. For example, four types of pass bandwidths are assumed in advance, and one of these is selected and the pass bandwidth of the band pass filter 15 is set. There are four types of passband widths that can be set: “wide band”, “medium band”, “narrow band”, and “extremely narrow band”. In the case of “broadband”, the passband width is set to about 200 kHz. In the case of “medium band”, the pass band width is set to about 150 kHz. In the case of “narrow band”, the pass band width is set to about 120 kHz. In the case of “extremely narrow band”, the pass band width is set to about 90 kHz.

  The reception state detection unit 17 detects the reception state of the broadcast signal based on the IF signal output from the band pass filter 15. For example, the signal strength of the IF signal, the presence / absence of multipath interference, and the presence / absence of adjacent interference are detected as reception states.

  The demodulator 20 performs FM demodulation processing and stereo demodulation processing based on the band-limited IF signal that has passed through the bandpass filter 15. RDS data including PI code, program content identification data (TYP), alternative frequency (AF) data, and the like is superimposed on the data after FM demodulation. The audio signal stereo-demodulated by the demodulator 20 is amplified by the amplifier 22 and an audio sound is output from the speaker 24.

  The RDS decoder 30 performs a predetermined decoding process on the data demodulated by the demodulator 20 and restores the RDS data. The RDS decoder 30 detects an error in the RDS data while performing block synchronization, and performs an operation for correcting the error. Normally, RDS data error detection and correction operations are separate from the RDS data decoding process, and a separate error detection / correction unit is provided.

  The control unit 40 controls the entire radio receiver. The control unit 40 includes a CPU, a RAM, a ROM, and the like, and performs various operations by executing a predetermined program. For example, a channel selection operation to select and receive a program, or an alternative broadcast station switching operation to search for and switch to another broadcast station that broadcasts the same content when the reception status of the broadcast signal being received deteriorates Is performed under the control of the control unit 40. For this purpose, the control unit 40 includes a channel selection processing unit 41, an AF data acquisition unit 42, a reception state determination unit 43, bandwidth determination units 44A and 44B, an AF check processing unit 45, a switching determination unit 46, and a mute processing unit 47. It has.

  When the received program is designated by the user using the operation unit 62, the channel selection processing unit 41 sets the reception frequency corresponding to the received program to the front end 12.

  The AF data acquisition unit 42 acquires alternative frequency data (AF data) included in the broadcast signal being received, extracts a reception frequency included in the acquired AF data, and creates an alternative frequency list (AF list). The created alternative frequency list is stored in the AF list storage unit 50. The reception state determination unit 43 determines the reception state of the broadcast signal being received based on the detection result by the reception state detection unit 17.

  The bandwidth determination unit 44A determines the pass bandwidth of the bandpass filter 15 corresponding to the broadcast signal being received based on the determination result by the reception state determination unit 43 corresponding to the broadcast signal being received. When the reception state of the broadcast signal being received is good, a wide bandwidth (for example, 200 kHz) is determined as the pass bandwidth of the bandpass filter 15. Further, when adjacent interference occurs and the reception state of the broadcast signal being received deteriorates, a determination is made to narrow the passband width of the bandpass filter 15 in order to prevent reception quality deterioration due to adjacent interference. The determined bandwidth is sent to the bandwidth setting unit 16, and the bandwidth setting unit 16 changes the pass bandwidth of the bandpass filter 15.

  The AF check processing unit 45 reads out the AF list stored in the AF list storage unit 50 at a predetermined timing (for example, when a deterioration of a certain time interval or reception state is detected), and includes each AF list stored in the AF list. An instruction to receive a broadcast signal of an alternative frequency is given to the front end 12 and a quality check is performed on each of these broadcast signals to determine the reception state of each broadcast signal. In this specification, a series of operations from reading the AF list to receiving a broadcast signal of an alternative frequency is referred to as “AF check”. The quality check is performed based on the detection results (signal strength of the IF signal, presence / absence of multipath interference, presence / absence of adjacent interference) by the reception state detection unit 17.

  The bandwidth determination unit 44B determines the pass bandwidth of the bandpass filter 15 for the broadcast signal to be subjected to AF check based on the determination result by the reception state determination unit 43 corresponding to the broadcast signal being received. Specifically, the better the reception state of the broadcast signal being received, the wider the pass band width of the band-pass filter 15, and the worse the reception state, the narrower the pass bandwidth.

  The switching determination unit 46 compares the reception state of each broadcast wave of the alternative frequency determined by the AF check processing unit 45 with the reception state of the broadcast signal being received determined by the reception state determination unit 43, and determines the alternative frequency. When the reception state of the broadcast signal is better, the front end 12 is instructed to switch to this broadcast signal.

  In parallel with the operation of the AF check processing unit 45, the mute processing unit 47 sends an instruction to the demodulation unit 20 so that the audio sound output from the speaker 24 is silenced. Instead of abrupt silence, the output sound fade-out process may be performed prior to the operation of the AF check processing unit 45, and the output sound fade-in process may be performed after the operation ends.

  The bandpass filter 15 described above is a band pass means, the reception state detection unit 17, the reception state determination unit 43 is a reception state determination unit, the bandwidth determination unit 44B is a bandwidth determination unit, the bandwidth setting unit 16, and the reception state. The detection unit 17 and the AF check processing unit 45 correspond to the alternative broadcasting station determination unit, the switching determination unit 46 corresponds to the switching unit, and the demodulation unit 20, the amplifier 22, the speaker 24, and the mute processing unit 47 correspond to the audio output unit.

  The radio receiver of this embodiment has such a configuration, and the operation thereof will be described next. FIG. 3 is a flowchart showing an operation procedure for performing AF check by changing the pass bandwidth of the bandpass filter 15 according to the reception state of the broadcast signal being received.

  While one of the broadcast signals is being received when the vehicle is traveling (step 100), the AF check processing unit 45 determines whether it is the AF check timing (step 102). If it is not the AF check timing, a negative determination is made, and the process returns to step 100 to repeat the broadcast signal reception operation. Further, when the AF check timing comes, an affirmative determination is made in the determination of step 102.

  Next or in parallel with the reception operation of the broadcast signal, the reception state detection unit 17 detects the reception state of the broadcast signal being received (step 104). The reception state determination unit 43 determines whether or not the detected reception state is the best state A (step 106). In the present embodiment, the reception state is classified into four stages, and the best state is A, and the reception state becomes B, C, and D as the reception state deteriorates. If the reception state is A, an affirmative determination is made in the determination of step 106. In this case, the bandwidth determination unit 44B determines the pass bandwidth of the bandpass filter 15 to be “wideband” for the broadcast signal to be subjected to AF check, and setting by the bandwidth setting unit 17 is performed (step 108). .

  If the reception state is not A, a negative determination is made in the determination of step 106. Next, the reception state determination unit 43 determines whether or not the detected reception state is the next best state B (step 110). If the reception state is B, a positive determination is made. In this case, the bandwidth determination unit 44B determines the pass bandwidth of the bandpass filter 15 as “medium band” for the broadcast signal to be subjected to AF check, and the setting by the bandwidth setting unit 16 is performed (step 112). ).

  If the reception state is not B, a negative determination is made in the determination in step 110. Next, the reception state determination unit 43 determines whether or not the detected reception state is a bad state C (step 114). If the reception state is C, a positive determination is made. In this case, the bandwidth determination unit 44B determines the passband width of the bandpass filter 15 as “narrow band” for the broadcast signal to be subjected to AF check, and setting by the bandwidth setting unit 16 is performed (step 116). ).

  If the reception state is not C, a negative determination is made in the determination of step 114. In this case, the bandwidth determining unit 44B determines the pass bandwidth of the bandpass filter 15 to be “extremely narrow band” for the broadcast signal to be subjected to AF check, and the setting by the bandwidth setting unit 16 is performed (step). 118).

  After the pass bandwidth of the bandpass filter 15 is set in any one of steps 108, 112, 116, and 118 in this way, the AF check processing unit 45 performs the AF check, and each broadcast wave of the alternative frequency is set. Is determined (step 120). Next, the switching determination unit 46 compares the reception state of each broadcast wave of the alternative frequency determined by the AF check processing unit 45 with the reception state of the broadcast signal being received determined by the reception state determination unit 43. (Step 122), it is determined whether there is a broadcast signal (AF station) of an alternative frequency with a good reception state (Step 124). If it exists, an affirmative determination is made, and the switching determination unit 46 instructs the front end 12 to switch to this AF station, and switches to a broadcast signal of an alternative frequency (step 126). Further, when there is no AF station with a good reception state, a negative determination is made in the determination of step 124, the process returns to step 100 without switching to the broadcast signal of the alternative frequency, and the reception has been performed so far. The broadcast signal reception operation is repeated.

  FIG. 4 is a diagram showing the relationship between the reception state of the broadcast signal being received and the setting content of the bandwidth of the bandpass filter 15 at the time of AF check. In FIG. 4, “Reception state” indicates the reception state of the currently received broadcast signal, and “AF check bandwidth” indicates the setting content of the bandwidth of the bandpass filter 15 at the time of AF check. FIG. 5 is a diagram showing a specific relationship between the reception state and the pass bandwidth shown in FIG.

  As shown in FIG. 4, when the reception state of the broadcast signal being received is the best A and the next best B, the “wideband” or the next widest “ Set to “medium band”. This is because the reception state of the broadcast signal being received is good or relatively good, so that if there is an AF station with a reception state equal to or higher than that, it is switched.

  When the reception state of the broadcast signal being received is C, the pass band width of the bandpass filter 15 is set to a “narrow band”. This is intended to switch if there is an AF station that can receive well even if the reception state of the broadcast signal being received has deteriorated and is somewhat disturbed.

  Further, when the reception state of the broadcast signal being received is D, which is the worst, the pass band width of the bandpass filter 15 is set to the “extremely narrow band”. This is because the broadcast signal being received is so bad that it cannot be viewed, so that if there is an AF station that can be viewed even if it is disturbed, it is switched.

  As described above, in the radio receiver according to the present embodiment, the reception state of the AF station is determined by setting the passband width of the bandpass filter 15 according to the reception state of the broadcast signal being received. The time required for the AF search operation can be shortened as compared with the case where the pass bandwidth is varied according to the reception state of the station. Also, since the AF search operation is performed by variably setting the passband width of the bandpass filter 15 in accordance with the reception state of the broadcast signal being received, the AF search operation can be performed while eliminating adjacent interference as necessary. It becomes possible, and appropriate switching to the AF station can be performed.

  Further, since the reception state determination and the pass bandwidth determination can be performed by selecting from a plurality of candidates (four types), these determination operations and determination operations, and further, the pass bandwidth setting operation of the band pass filter 15 are performed. Can be simplified.

  Further, it is possible to switch to a broadcast signal having a better reception state in consideration of the reception state of the broadcast signal being received. For example, when the reception state of the broadcast signal being received is good, switching can be performed only when there is an AF station with a better reception state. Further, when the reception state of the broadcast signal being received is poor, it is possible to search for an AF station by lowering the value of the reception state serving as a reference for switching.

  In addition, for a radio receiver that receives a radio data system (RDS) broadcast signal, necessary alternative frequency data can be easily obtained. In particular, when a single tuner configuration in which background processing cannot be performed is adopted, it is possible to quickly switch to an AF station by performing an AF search operation in a short time.

  In addition, by applying to a radio receiver mounted on a vehicle, it is possible to surely search for and switch to a broadcast station of an alternative frequency while receiving a broadcast signal whose reception state changes according to the traveling of the vehicle. .

  In addition, this invention is not limited to the said embodiment, A various deformation | transformation implementation is possible within the range of the summary of this invention. For example, in the above-described embodiment, a radio receiver that receives RDS broadcasting has been described. However, other radio receivers, such as a DAB (Digital Audio Broadcasting) receiver, can be used as long as they can receive alternative frequency data. The invention can be applied. In the above-described embodiment, the reception state determination and the pass bandwidth setting are performed in four stages, but a plurality other than four can be used.

  As described above, according to the present invention, since the reception state determination of the alternative frequency broadcasting station is performed by setting the pass bandwidth of the band pass means according to the reception state of the broadcast signal being received, each alternative frequency The time required for the AF search operation can be shortened as compared with the case where the pass bandwidth is varied according to the reception state of the broadcast station.

12 Front end (F / E)
14 Intermediate Frequency Amplifier (IFA)
15 Bandpass filter (BPF)
16 Bandwidth setting unit 17 Reception state detection unit 30 RS decoder 40 Control unit 41 Channel selection processing unit 42 AF data acquisition unit 43 Reception state determination unit 44A, 44B Bandwidth determination unit 45 AF check processing unit 46 switching determination unit 47 Mute processing 50 AF list storage

Claims (10)

In a radio receiver that receives a broadcast signal on which alternative frequency data including frequency information of a broadcast station that broadcasts the same program as the broadcast signal being received is superimposed,
A front end for receiving broadcast signals and converting them to intermediate frequency signals;
Band-pass means for receiving an intermediate frequency signal output from the front end and passing a component included in a predetermined pass bandwidth;
Reception state determination means for determining the reception state of the broadcast signal being received;
Bandwidth determining means for determining the pass bandwidth of the band passing means according to the reception state determined by the reception state determining means;
An alternative of receiving a broadcast signal specified by the frequency information indicated by the alternative frequency data and determining its reception state in a state where the pass band width determined by the bandwidth determination unit is set in the band pass unit. Broadcasting station determination means;
A radio receiver comprising: In claim 1,
The radio receiver according to claim 1, wherein the bandwidth determination unit sets the pass bandwidth of the band pass unit wider as the reception state determined by the reception state determination unit is better. In claim 2,
The reception state determination means selects a corresponding one from a plurality of reception state levels classified according to the degree,
The radio receiver according to claim 1, wherein the bandwidth determination unit determines a pass bandwidth corresponding to the reception state level selected by the reception state determination unit. In any one of Claims 1-3,
When the reception state determined by the alternative broadcasting station determination unit is better than the reception state determined by the reception state determination unit, the frequency indicated by the alternative frequency data from the broadcast signal being received A radio receiver further comprising switching means for switching to a broadcast signal specified by information. In any one of Claims 1-4,
The radio receiver according to claim 1, wherein the alternative frequency data is included in a broadcast signal of a radio data system. In any one of Claims 1-5,
The radio receiver according to claim 1, wherein the front end has a single tuner configuration for receiving one broadcast signal. In claim 6,
A radio receiver characterized by further comprising audio output means for outputting sound corresponding to a broadcast signal being received and for making the output silent when the determination operation by the alternative broadcast station determination means is being performed . In any one of Claims 1-7,
The reception state determination by the reception state determination unit and the alternative broadcasting station determination unit is performed according to the signal strength of the intermediate frequency signal, the presence / absence of multipath interference, and the presence / absence of adjacent interference. Receiving machine. In any one of Claims 1-8,
A radio receiver that is mounted on a vehicle. In claim 9,
A radio receiver characterized in that the alternative broadcast station determination means performs an operation of determining a reception state of a broadcast station of an alternative frequency when a reception state of a broadcast signal being received deteriorates at a constant time interval.

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