JPH11196009A - Radio receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a case that the outer sounds of a loudspeaker are interrupted or become discontinuous due to the frequent switching actions between the digital audio broadcast and the analog auido broadcast with data and to avoid giving unpleasant feelings to the users by the use of a switching suppression means that suppresses the switching actions. SOLUTION: A DAB/RDS switching program is executed at each fixed time interval, while a DAB/RDS car radio is selecting the output sent from a DAB tuner part. In a step S70, it is decided whether the DAB reception sensitivity is less than the lowest allowable level C1, when the switching program is executed at the precedent time. In a step S72, it is decided whether the DAB receiving sensitivity is less than the level C1 this time also. Then a timer value is incremented by 1 in a step S74. In a step S76, it is decided whether a state in which the DAB receiving sensitivity is kept at less tan the level C1 has lasted for a fixed time or longer. Then a switch is changed from a DAB tuner part to an RDS tuner part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to, for example, DAB
(Digital Audio Broadcasti
ng) and RDS (Radio Data System)
The present invention relates to a radio receiver that supports both digital audio broadcasting and analog audio broadcasting with data as in m), and more particularly to a radio receiver that can improve switching between digital audio broadcasting and analog audio broadcasting with data.

[0002]

2. Description of the Related Art In some cases, the same radio program is simultaneously broadcast in both DAB as digital audio broadcasting and RDS as analog audio broadcasting with data. DAB / RDS dual-purpose car radio uses DAB
Is received preferentially, and when the reception sensitivity of DAB is deteriorated, D
When switching from AB to RDS is performed, the same radio program of RDS is output, and the reception sensitivity of DAB is restored,
Switching from RDS to DAB is performed, and the DAB radio program is output again.

FIG. 11 shows a DAB broadcasting the same radio program.
And RDS when they are present. The electric field strength of the RDS and DAB decreases as the distance from the center of the cover area decreases, and the cover area of the DAB becomes narrower than that of the RDS. DAB / RD
The S dual-use car radio moves with the movement of the car on which it is mounted, and the reception sensitivity of the DAB changes. Conventional DA
In the B / RDS dual-use car radio, it is determined whether or not the reception sensitivity of the DAB is equal to or higher than an allowable minimum level. If the reception sensitivity is equal to or higher than the allowable minimum level, the DAB is selected.

[0004]

After the user selects a DAB radio program at the location P1 in FIG. 11, that is, a location where the electric field strength is sufficiently large within the DAB coverage area, the automobile is moved to the DAB coverage area. Consider a case where the user moves toward the periphery and moves along the periphery from the place P2 to the place P3. In the movement from P2 to P3, the car
Since the rim of the cover area of B frequently moves in and out, the conventional car radio for both DAB and RDS uses
The reception sensitivity of DAB frequently fluctuates up and down with respect to an allowable minimum level, and the frequency of switching between digital audio broadcasting and analog audio broadcasting with data increases. For the same radio program, digital audio broadcasting is delayed about 1 second from analog audio broadcasting with data, and mute (silence) is applied when switching between digital audio broadcasting and analog audio broadcasting with data. Frequent switching between broadcasting and analog audio broadcasting with data causes interruption or discontinuity of the sound output from the speaker, giving the user discomfort.

It is an object of the present invention to provide a radio receiver which overcomes the above-mentioned problems.

[0006]

A radio receiver according to the present invention.
In (10), when the same radio program is simultaneously broadcast in both digital audio broadcasting and analog audio broadcasting with data in a broadcast format, if the receiving sensitivity of the digital audio broadcasting deteriorates, the same Switching from digital audio broadcasting for a program to analog audio broadcasting with data, and when the reception sensitivity of the digital audio broadcasting is restored, switching from analog audio broadcasting with data for the same radio program to digital audio broadcasting. The radio receiver (10) has switching suppression means for suppressing switching between digital audio broadcasting and analog audio broadcasting with data.

[0007] The radio receiver (10) is not limited to a radio receiver mounted on an automobile. The user is a car,
It also includes a portable radio receiver that can be brought into a train, ship, etc. as appropriate. Further, the radio receiver (10) does not necessarily have to be mounted on a moving body such as an automobile. It may be installed in a house or the like near the periphery of the DAB cover area as digital audio broadcast.

[0008] Digital audio broadcasting and analog audio broadcasting with data are not limited to DAB and RDS, respectively. Analog audio broadcasting with data is A
There is also a case of M broadcast.

[0009] In the vicinity of the digital audio broadcast coverage area, the reception sensitivity of the digital audio broadcast is reduced, and for example, fluctuates near the permissible minimum level. If digital audio broadcasting and analog audio broadcasting with data are simply selected depending on whether they are above or below the permissible minimum level, the digital audio broadcasting reception sensitivity may fluctuate up or down from the permissible minimum level. Switching between digital audio broadcasting and analog audio broadcasting with data frequently occurs in a radio program of simultaneous broadcasting of audio broadcasting and analog audio broadcasting with data, which gives a user an unpleasant feeling. On the other hand, the switching suppressor suppresses switching between digital audio broadcasting and analog audio broadcasting with data, so that frequent switching between digital audio broadcasting and analog audio broadcasting with data is avoided, and discomfort to the user is avoided. Can be prevented.

[0010] According to the radio receiver (10) of the present invention, the switching suppressing means changes the reception sensitivity value of the digital audio broadcast as a condition for switching from the analog audio broadcast with data to the digital audio broadcast from the digital audio broadcast to the data. The value is set to a value higher than the value of the receiving sensitivity of digital audio broadcasting as a condition for switching to analog audio broadcasting with tag.

The value of the receiving sensitivity of the digital audio broadcasting as a condition for switching from the analog audio broadcasting with data to the digital audio broadcasting is based on the value of the receiving sensitivity of the digital audio broadcasting as the condition for switching from the digital audio broadcasting to the analog audio broadcasting with data. As a result, the switching from the analog audio broadcast with data to the digital audio broadcast is performed only after the reception sensitivity of the digital audio broadcast has reached an appropriately large value. As a result, re-switching from digital audio broadcasting to analog audio broadcasting with data is reduced, and the frequency of switching between DAB and RDS is reduced.

According to the radio receiver (10) of the present invention, the receiving sensitivity of digital audio broadcasting is detected based on the bit error rate.

Since there is a correlation between the receiving sensitivity of digital audio broadcasting and the bit error rate, the receiving sensitivity of digital audio broadcasting can be detected from the bit error rate.

According to the radio receiver (10) of the present invention, the switching suppressing means provides a delay time for switching between the digital audio broadcast and the analog audio broadcast with data, and when the switching condition disappears within the delay time. , To stop the switching.

Switching between digital audio broadcasting and analog audio broadcasting with data is not performed immediately, but a delay time is provided. Within this delay time, switching such as recovery or re-deterioration of the reception sensitivity of the digital audio broadcasting is performed. When the condition disappears, the switching is stopped. As a result, useless switching is suppressed, and the switching frequency is reduced.

The radio receiver (10) of the present invention is mounted on an automobile.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 is a block diagram of the DAB / RDS dual-use car radio 10. Outputs of the media player 12, such as a CD player, the RDS tuner unit 14, and the DAB tuner unit 16 are sent to the switch 18. The microcomputer 20 controls the connection between the volume 22 and the media player 12, the RDS tuner unit 14, and the DAB tuner unit 16 via the switch 18, and controls the media player 12, RD
One selected from the outputs of the S tuner section 14 and the DAB tuner section 16 is sent to the volume 22. Volume 22
Adjusts the volume of the sound output from the speaker 24, and the output of the volume 22 is amplified by the amplifier 26 and then output from the left and right speakers 24. The user's instruction to the DAB / RDS dual-use car radio 10 is made by the key 28, and the input of the key 28 is sent to the microcomputer 20.
28, a predetermined input is made to the microcomputer 20, and the microcomputer 20 displays various information on a display.
Display at 30 to inform the user. Memory 32 is RAM
The microcomputer 20 reads and writes data.

FIG. 4 is a detailed diagram of the RDS tuner section 14 of FIG. The RDS FM composite signal from the antenna is PL
The signal is sent to the L receiving circuit 36. In the PLL receiving circuit 36, a predetermined FM composite signal is selected, amplified, detected, and sent to the muting circuit 38. The RDS data demodulation circuit 40 extracts and demodulates a data portion from the FM composite signal selected by the PLL reception circuit 36, and outputs the demodulated data to the microcomputer 20. Microcomputer 20
Decodes the input from the RDS data demodulation circuit 40, stores it in the memory 32, and displays on the display 30 the data such as the reception frequency and the radio program name relating to the RDS being received. The reception sensitivity detection circuit 42 detects the reception sensitivity of the FM reception signal selected by the PLL reception circuit 36, and outputs the detection result to the microcomputer 20. The microcomputer 20 detects the electric field strength of the received signal based on the input from the reception sensitivity detection circuit 42 as, for example, an S meter output.
It is determined whether or not a reception condition of not less than dB μV and a noise level at an IF output of not more than 1.5 V is satisfied,
When the condition is satisfied, the muting circuit 38 is deactivated, and the demodulated RDS audio signal is output to the switch 18. If the above-mentioned reception condition is not satisfied, the muting circuit 38 is activated, and the output of the RDS audio signal to the switch 18 is stopped.

FIG. 5 is a system configuration diagram of the DAB tuner unit 16. The system microcomputer unit 52 and the control microcomputer unit 54 are included in the microcomputer 20 and include memory units 56 and 58 as the memory 32, respectively. The system microcomputer unit 52 includes a plurality of ensembles (each ensemble is transmitted by a radio broadcast wave modulated by DQPSK-OFDM, and one ensemble has a bandwidth of about 1.5 MHz, and usually includes six ensembles, That is, one ensemble is designated from among the broadcast programs.), And the reception frequency data relating to the designated ensemble is transmitted to the RF block 60. RF block 60
The RF (Radio Frequency) of the specified ensemble is extracted from the system microcomputer unit 52 and sent to the demodulation block 62. The demodulation block 62 demodulates the RF signal from the RF block 60 based on the demodulation start data information from the system microcomputer section 52, and outputs the demodulated signal to the channel decoding block 64. The channel decoding block 64 decodes the demodulated signal from the demodulation block 62 based on the reception mode data and the decoded channel separation data from the system microcomputer unit 52, and outputs FIC data (described later) and error rate data (representing a bit error rate). ) Is output to the system microcomputer unit 52, and the decoded audio information is output to the audio decoding block 66. Audio decoding block 66
Is the MPEG header data from the system microcomputer 52,
Based on the MPEG error data and the PAD data (program-related data), audio information of a predetermined service is selected from the input from the channel decoding block 64 and output as sound.

In FIGS. 6 to 10, communication protocols of various elements of the DAB such as a transmission frame are described as appropriate. For details, see the European Telecommunications Standards Association (European Telecommunications).
nations Standard RDS Insti
European Telecommunications Standard (European Telecommunications)
ionics Standard).

FIG. 6 shows the structure of a DAB transmission frame. Transmission frame (Transmission fra
me) is the synchronization channel, FIC (Fast)
Information Channel) and M
It has SC (Main Service Channel). The FIC further includes a plurality of FIBs (Fast
Information Block), MS
C is a plurality of CIFs (Common Inter
left Frame). The DAB has specifications from mode 1 to mode 3, and the transmission frame time (duration) and the number of FIBs and CIFs in one transmission frame are different for each mode. For example, in mode 1, the time of one transmission frame is 9
The number of FIBs and CIFs in one transmission frame of 6 ms is 12 and 4, respectively.

FIG. 7 is a view showing an example of the DAB service structure. Ensemble label is DAB Ensemble 1 (DA
B ENSEMBLE ONE) is an ensemble (Ensemble) whose service label is alpha1.
Radio (ALPHA1 RADIO), Beta Radio (BETA RADIO), Alpha 2 Radio (ALP)
HA2 RADIO) and other services (Servi
ce). The user will hear the selected service from 10.

Alpha 1 radio is primar
y) Service component (Servicecomponent)
ts) and two secondary service components. The main service component is audio, and the secondary service component is a traffic message channel: TMC (Traffic Me).
sage channel and service information: SI (S
service Information). The audio component and SI are stored in separate subchannels (S
ubCh), and the TMC is the FIDC in the FIC.
(Fast Information Data Ch
ann).

A beta radio has two service components.
Audio and secondary audio (secondary a
audio component), both of which are MS
On the C subchannel.

The alpha 2 radio has the same TMC and SI as the alpha 1 radio, and the audio may be the same as the alpha 1 radio depending on the switch.

FIG. 8 is a structural diagram of the FIB. FIB
A total of 256 bits, the first 30 bytes of FI
B data area (FIB data field) and rear 16-bit CRC (Cyclic Redunda)
ncy Check word). The FIB data area further includes a plurality of FIG (Fas
t Information Group), one end marker (Endmarker), and one padding (filling the remaining bits with 0s to fit the FIB data area to bytes). The part of FIG is a useful data area (useful data view).
ld). Each FIG is, in order from the beginning, a FIG type, a Length (length: represents a bit length of a subsequent FIG data area), and a FIG data area (FIG.
data field). Fig type and Le
ngth forms a FIG header.

FIG. 9 is a structural diagram of the FIG data area of FIG. 8 in which the FIG type is 0 (000 in 3-bit binary notation). The FIG data area further stores C / N
(Current / Next), OE (Other E)
nsemble), P / D (Programme / Da
ta), Extension, Type 0 area (Type
0 field). Extension is 1 to 4
And 7, when C / N = 0, it means the current multiplex structure, and when C / N = 1, it means the next multiplex structure. Also, C / N =
When it is 1, it means that the type 0 area is related to the following arrangement. Extension is 6, 9, 11, 1
In the case of 8, 21, 22, 23, 24, 25, 27, and 30, C / N indicates the version number of the type 0 area.
OE is Extension = 12, 16, 17, 21,
24, 30 are used, and OE = 0 indicates this type 0
The information of the area means that it is related to this ensemble, and OE = 1 means that it is related to another ensemble. P / D = 1 indicates SId of type 0 area
Is the 16-bit Sid used for program services
, And P / D = 0 indicates that S in the type 0 area
If Id is the 32 bit S indicator used for data service
Id. This P / D is Extnsi
It is used when on is 2, 9, 23, 24, and when it is not used, SId has a 16-bit format.

FIG. 10 shows the Extends of FIG.
ion is 21 (hereinafter each FIG is referred to as a FIG type and an Ext
and "engion" as shown in FIG. FIG. 2 is a structural diagram of a type 0 area. The type 0 area further includes a plurality of pieces of frequency information (Frequency inf).
operation area). To explain the main items in each frequency information, Regionid indicates a region to which this frequency information applies, and thereafter,
A plurality of FIlists (FI list: frequency information list) follow. The frequency list (Freq list) includes an alternative frequency (alternative frequency) broadcasting the same program as the program of the DAB service.
cy) is written, and when the R & M of the header (Header) of each FIlist is 100, the alternative frequency written in the frequency list is particularly R
This indicates that the frequency is DS. Note that R & M =
When it is 101, it indicates that the alternative frequency written in the frequency list is for AM broadcasting. In this way, from the information of FIG0 / 21, it is possible to acquire the frequency information of the RDS that is broadcasting the same radio program as the radio program currently being broadcast by the predetermined DAB service.

FIG. 1 is a flowchart of a program for switching from DAB to RDS for the same radio program.
The DAB to RDS switching program is executed at regular time intervals (a time interval corresponding to one increment of the timer in step S74) during a period when the DAB / RDS dual-use car radio 10 is selecting the output from the DAB tuner unit 16. Is done. In step S70, when this program was executed last time, it is determined whether or not the reception sensitivity of DAB is lower than the allowable minimum level C1.
Proceed to 72, and if no, terminate the program.
The fact that the reception sensitivity of the DAB is lower than the allowable minimum level C1 means that the electric field strength of the DAB is weak enough to output the DAB. DAB reception sensitivity can be detected from the bit error rate and the number of error bits in the bit stream. In step S72, it is determined whether the reception sensitivity of the DAB is lower than the allowable minimum level C1. If yes, the process proceeds to step S74. If no, the process proceeds to step S80. Step S
At 74, the timer is incremented by one, and the process proceeds to step S76. In step S80, the timer is reset, and the program ends. In step S76, it is determined whether or not the value of the timer is equal to or greater than a predetermined value Ta,
The state in which the reception sensitivity of the DAB is less than the predetermined value C1 is a predetermined time,
For example, it is determined whether or not it has continued for 10 seconds or more.
If es, proceed to step S78, if no,
The program ends. In step S78, the switch 18 in FIG. 3 is switched from the DAB tuner unit 16 to the RDS tuner unit.
Switch to 14.

FIG. 2 is a flowchart of a program for switching from RDS to DAB for the same radio program.
The program for switching from DAB to RDS is a fixed time interval (a time interval corresponding to one increment of the timer in step S90; a time interval during which the DAB / RDS dual-use car radio 10 selects the output from the RDS tuner unit 14). In the embodiment, it is set to be equal to the execution interval in FIG. In step S86, when this program was executed last time,
It is determined whether or not the DAB reception sensitivity is equal to or higher than C2 that is appropriately larger than the minimum allowable level C1. If yes, the process proceeds to step S88. If no, the program ends. DAB reception sensitivity of C2 or higher means that DAB
This means that the electric field intensity of B is sufficiently increased and DAB can be output stably. In step S88, this time, D
It is determined whether or not the receiving sensitivity of AB is equal to or higher than C2, and
If s, the process proceeds to step S90. If no, the process proceeds to step S92. In step S90, the timer is set to 1
And the process proceeds to step S94. In step S92, the timer is reset, and the program ends. In step S94, the value of the timer is set to the predetermined value Tb.
(Tb may or may not be equal to Ta). If the determination is yes, the process proceeds to step S96. If the determination is no, the program ends. In step S96, the switch 18 in FIG. 3 is switched from the RDS tuner unit 14 to the DAB tuner unit 16.

[Brief description of the drawings]

FIG. 1 is a flowchart of a program for switching from DAB to RDS for the same radio program.

FIG. 2 is a flowchart of a program for switching from RDS to DAB for the same radio program.

FIG. 3 is a block diagram of a DAB / RDS dual-use car radio.

FIG. 4 is a detailed view of an RDS tuner section 14 of FIG.

FIG. 5 is a system configuration diagram of a DAB tuner unit.

FIG. 6 is a diagram showing the structure of a DAB transmission frame.

FIG. 7 is an exemplary diagram of a DAB service structure;

FIG. 8 is a structural diagram of an FIB.

FIG. 9 is a structural diagram of a FIG data area in which FIG type is 0 in FIG. 8;

FIG. 10 is a structural diagram of FIG0 / 21 of FIG. 9;

FIG. 11 shows DAB and RDS broadcasting the same radio program
FIG. 7 is a diagram showing the coverage areas of those radio waves when there is a radio wave;

[Explanation of symbols]

10 DAB / RDS dual-use car radio (radio receiver)

Claims (5)

[Claims] When receiving a radio program in a situation where the same radio program is simultaneously broadcast in both a digital audio broadcast and an analog audio with data broadcasting format, if the reception sensitivity of the digital audio broadcast deteriorates, the same radio program is received. A radio receiver adapted to switch from digital audio broadcasting relating to a program to analog audio broadcasting with data and, when the receiving sensitivity of the digital audio broadcasting is restored, to switch from analog audio broadcasting with data relating to the same radio program to digital audio broadcasting. (10) The radio receiver according to (10), further comprising a switching suppression unit that suppresses switching between digital audio broadcasting and analog audio broadcasting with data. 2. The switching suppression means according to claim 1, wherein the value of the receiving sensitivity of the digital audio broadcasting as a condition for switching from the analog audio broadcasting with data to the digital audio broadcasting is changed as a condition for switching from the digital audio broadcasting to the analog audio broadcasting with data. 2. The radio receiver according to claim 1, wherein the value is higher than the value of the reception sensitivity of the audio broadcast. 3. The radio receiver according to claim 2, wherein the reception sensitivity of the digital audio broadcast is detected based on a bit error rate. 4. The switching control means according to claim 1, wherein a delay time is provided for switching between the digital audio broadcast and the analog audio broadcast with data, and when the switching condition disappears within the delay time, the switching is stopped. The radio receiver according to any one of claims 1 to 3, wherein: 5. The radio receiver according to claim 1, which is mounted on an automobile.