JPH1155213A - Dab signal receiving method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten a time required for seek tuning. SOLUTION: The frequencies of all receivable DAB(digital audio broadcast) signals are searched by the operation of a search key FLSK, and stored in a frequency reception history storage part 21. A control part 17 controls a front end 12a-1 and a PLL 12a-2 so that the DAB signal of the frequency stored in the frequency reception history storing part 21 can be received by the turning operation of a seek key SK.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for receiving a DAB signal in a DAB receiver.
The present invention relates to a DAB signal receiving method in which the frequency of an AB signal is searched and stored, and the DAB signal is received in synchronization with the stored frequency by a tuning operation of the DAB signal.

[0002]

2. Description of the Related Art Digital audio is now widely recognized for its excellent characteristics and ease of use, and is rapidly becoming popular. Against this background, digitalization of audio broadcasting has become active and digital audio broadcasting DAB (Digital Audio Broadcasting) has been realized in Europe.

FIG. 6 shows a mode II DAB broadcast signal frame structure employed in a DAB system. One frame length is 24 ms, and a two-symbol synchronization part SYNC is used.
And FIC (Fast Inf)
or the main service channel (MSC) of 72 symbols. The synchronization unit SYNC includes a null symbol and a phase reference symbol PRS used for recognizing a start point of a frame.
Contains. The high-speed information channel unit FIC has three-symbol high-speed information blocks FIB1 to FIB3 (FIB: First Informati
on Block), and includes various information such as service label, service component label, service sequence data, and program type code (PTY).

The main service channel MSC is divided into 72 data fields (symbols), a broadcast signal of a predetermined service (program) is inserted into each data field, and 6 to 8 services (simultaneously) are transmitted from one broadcasting station. Program) can be transmitted. Which service corresponds to which data field is specified by the service array data included in the high-speed information channel unit FIC. Each of the high-speed information blocks FIB1 to FIB3 of the high-speed information channel FIC has a hierarchical structure as shown in FIG.
The specified data is inserted into the data field 142 specified by the tension 141. That is, each of the high-speed information blocks FIB1 to FIB3 includes a 256-bit (30-byte) FIB data field 111 and a CRC 112, and the FIB data field 111 includes a plurality of FIGs 121 to 123. ing.

Each FIG (Fast Information Group) 121-12
3 are (1) FIG type 131 and (2) Le
ngth (byte length of FIG data field) 132, (3) FIG data f
ield133, and FIG data field 133 contains Exte
nsion 141 (FIG. extended identification number) and data field 142 are included. In the data field 142, various data such as a service label, a service component label, service arrangement data, a program type code PTY, a supported announcement type, a broadcast station list for each region, and the like are inserted. Although the frame configuration of mode II for satellite broadcasting using the 1.5 GHz band has been described above, the frame configuration of mode I using the frequency band of 50 MHz to 250 MHz has almost the same configuration, and one frame length is 96 ms.
It has become.

FIG. 7 is a diagram showing the configuration of a DAB transmitter.
Reference numeral 1m denotes a data compression unit for encoding an analog audio signal (audio signal of each service) into MPEG audio data with high efficiency. 2a to 2m are transmission path coding units for adding an error / detection correction code, and 3 is a multiplexing unit, which outputs output data of each of the transmission path coding units 2a to 2m according to service sequence data. It is mapped to a field (symbol) and time-division multiplexed.
4 is an interleave / OFDM modulator, and IDFT
OFDM (Orthogonal Inverse)
Frequency division multiplexing is performed, and interleaving is performed by rearranging the order of multiplexed signals in a symbol according to a predetermined format. That is, OFD
The M modulator divides each symbol (phase reference symbol, data symbol) into N sets of 2 bits each, differentially encodes the first data of each set as a real part and the second data as an imaginary part, and performs differential coding of the differential code. The real part and the imaginary part are sequentially input to the inverse Fourier transform unit and subjected to IDFT processing to output a baseband modulated wave. Numeral 5 is a quadrature modulation that converts a real part and an imaginary part output from the interleave / OFDM modulator into analog signals, multiplies each by a cos wave and a sin wave of a transmission local frequency fc, and combines the multiplication results to perform orthogonal transformation. A unit 6 is a frequency conversion unit that converts a transmission carrier obtained by quadrature modulation into an RF signal, and 7 is a transmission power amplifier.

FIG. 8 is a configuration diagram of a DAB receiver. 11
Denotes an antenna, 12 receives a desired DAB broadcast signal wave,
DA that outputs a baseband analog signal by performing quadrature demodulation
RF signal demodulation unit for B, 13 is an AD converter that converts a baseband analog signal into digital data at a predetermined sampling frequency, 14 is high-efficiency code data (MPEG audio data) by performing FFT demodulation processing, differential decoding processing, etc.
A transmission line decoding circuit for restoring / outputting the audio data; 15 an audio decoding unit for decoding MPEG audio data into original PCM audio data; 16 a DA converter for converting PCM audio data to an analog audio signal;
17 is a control unit for controlling the entire receiver, 18 is a display unit 18
a, an operation / display unit including an operation unit 18b.

[0008] Mode I RF for DAB of 50 MHz to 250 MHz
The signal demodulation unit 12 includes a tuner unit 12a and a quadrature demodulation unit 12b as shown in the figure. In modes II and III, a 1.5 GHz band is used, so a down converter is required. The tuner unit 12a receives the DAB signal radio wave and
It converts the signal into an F signal, and includes a front end 12a-1 and a PLL circuit (local oscillation circuit) 12a-2 which outputs a local oscillation frequency signal corresponding to a desired DAB broadcast frequency. The quadrature demodulator 12b reproduces and outputs the baseband signals I (t) and Q (t) from the analog IF signal.

The transmission line decoding circuit 14 includes an FFT differential demodulation unit 14a, a selective decoding unit 14b, and a deinterleave unit 1.
4c and the like. The FFT differential demodulation unit 14a outputs the digital data I (m), Q
(m) is subjected to FFT processing and differential decoding processing to demodulate the interleaved transmission data. Deinterleave 14
c deinterleaves the output data of the FFT differential demodulation unit to return to the original data sequence, and the selective decoding unit 14b performs error detection and correction processing on the deinterleaved data and controls the contents of the high-speed information channel unit FIC. Input to the unit 17. The control unit 17 detects the symbol position of the service (program) specified by the user based on the service arrangement data included in the high-speed information channel unit FIC, and notifies the selective decoding unit 14b. The selective decoding unit 14 b outputs the decoded data (MPEG audio data) of the notified symbol to the audio decoding unit 15. The audio decoding unit 15 converts the input MPEG audio data into the original PC
Convert to M audio data and output. Control unit 1
Numeral 7 sends the label (program name) included in the high-speed information channel FIC to the operation unit as appropriate according to the user's request and displays it.

FIG. 9 is a flowchart of a conventional seek channel selection process, and FIG. 10 is an explanatory diagram of a seek channel selection operation. DAB signal (ensemble) frequencies are arranged at frequency intervals that are multiples of 16 kHz (arrows in FIG. 10). However, at present, there are few DAB broadcast stations (DAB-1 to DAB-3) and the frequency used is small. When the seek key on the operation unit 18b is operated during the reception of the DAB broadcast, the control unit 17 regards the adjacent station frequency larger by Δf (= 16 kHz) than the current reception frequency as the reception frequency, and sets the PLL circuit to the frequency. (Step 101).
Next, the reception electric field intensity E is measured by a reception electric field intensity detection unit (not shown) (step 102), and it is checked whether the reception electric field intensity E is equal to or higher than the set level Es (step 103).

If E ≧ Es, synchronization control is performed by a synchronization circuit (not shown), and it is checked whether synchronization has been achieved by referring to the output signal SYN (steps 104 and 105).
If the synchronization is OK, the seek selection is terminated. However, in step 103, the reception electric field strength E is set to the set level Es.
If (E <Es) or the synchronization is NG in step 105, the process returns to step 101,
The control unit 17 regards the adjacent station frequency larger by Δf than the current reception frequency as the reception frequency and repeats the subsequent processing. Then, a DAB broadcast signal of a predetermined frequency is finally received, and the seek ends. It should be noted that since 64 types of frequencies that are currently likely to be broadcast in Europe are defined, do not seek at 16 kHz intervals, and perform the processing in FIG. 9 using 64 types of known frequencies in advance as seek target frequencies. Can also. .

[0012]

In the DAB broadcasting system, the DAB broadcasting frequency is arranged at a frequency that is a multiple of 16 kHz, and 64 types of frequencies that can be currently broadcast in Europe are defined. I have. However, the number of DAB broadcasting stations that actually perform DAB broadcasting is small. That is, the DAB broadcast frequency actually used is small. Therefore, the frequency interval between the DAB broadcast frequencies actually used is large, and a large number of unused DAB broadcast frequencies exist between them.

Therefore, after the seek channel selection operation, another DAB
It takes a considerable amount of time to receive a broadcast signal, and the time during which the output sound is interrupted becomes longer, causing a problem of giving the user discomfort. Specifically, it takes about 0.5 to 2 seconds to detect whether the reception is possible or not in synchronization with one frequency. For this reason, when the user seeks to select a DAB broadcast having a frequency different from that of the currently received DAB broadcast, all the DAB frequencies that may be being broadcast must be searched in order. take time. or,
As described above, it takes a long time to select a seek channel. Therefore, naturally, there is a problem that a longer time is required until a desired program is selected by a seek operation. As described above, an object of the present invention is to provide a DAB receiving method of a DAB receiver that can reduce the time required for seek channel selection and the time required for channel selection of a desired program.

[0014]

According to the present invention, there is provided a means for searching and storing frequencies of all receivable DAB signals, and tuning to the stored frequencies by selecting a DAB signal. This is achieved by a DAB receiver comprising means for receiving a DAB signal. In this case, a search key is provided for frequency search of all receivable DAB signals,
Automatically in the background processing by operating the search key or when another audio source is selected.

Further, according to the present invention, an area where a vehicle is located is determined by using data included in a high-speed information channel of a DAB broadcast signal. This is achieved by outputting a signal indicating a frequency search for the DAB signal. In this way, the user can be notified of the frequency search timing, and the user can perform the frequency search in a timely manner. As a result, the frequency search is not performed frequently, so that the time for outputting the DAB broadcast sound can be extended, and moreover,
The frequency information does not become obsolete, and the DAB signal can be reliably sought and received by the seek channel selection operation.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION

(A) Configuration of DAB Receiver FIG. 1 is a configuration diagram of a DAB receiver of the present invention. 11 is an antenna, 12 is for receiving a desired DAB broadcast signal wave, and
The signal is quadrature demodulated and the baseband analog signal I (t),
A DAB RF signal demodulation unit that outputs Q (t), 13 is an AD converter that converts a baseband analog signal into digital data I (m) and Q (m) at a predetermined sampling frequency, 14 is FFT demodulation processing, A transmission line decoding circuit that restores / outputs high-efficiency encoded data (MPEG audio data) by performing dynamic decoding processing or the like, 15 is an audio decoding unit that decodes MPEG audio data into original PCM audio data, and 16 is PCM audio data. A DA converter for converting data into an analog audio signal, 17 a control unit for controlling the entire receiver, 18 an operation / display unit, and a display unit 1
8a and an operation unit 18b. The operation unit is provided with a seek key SK for channel selection and a search key FLSK for instructing a search for all receivable DAB signal frequencies. 19 is a reception electric field strength detection unit (RSSI: ReceiveSignal Strength).
Indicator), which detects the received electric field intensity E from the IF signal or the baseband signal and inputs it to the control unit 17.

The control unit 17 includes a processor (CPU) 17
a, ROM 17b for storing programs, RAM 17c
The frequency reception history storage unit 21 is provided in the RAM 17c.
And a frequency block table 22 are provided. The frequency reception history storage unit 21 stores a frequency reception history, and the frequency block table 22 stores a data group (for example, 64 types of frequency data groups in Europe) indicating frequencies that may be DAB broadcast. You.

Mode I DAB RF signal demodulator 12
Is a tuner section 12a and a quadrature demodulation section 1 as shown in FIG.
Although it is composed of 2b, mode II and III use a 1.5 GHz band, so a down converter is required. The tuner section 12a receives the DAB signal radio wave and converts it into an IF signal. The tuner section 12a-1 includes a front end 12a-1 and a PLL circuit (local oscillation circuit) 12a- that outputs a local oscillation frequency signal corresponding to a desired DAB broadcast frequency. It consists of two. The quadrature demodulation unit 12b outputs the baseband signal I from the analog IF signal.
(t) and Q (t) are output.

The transmission line decoding circuit 14 includes an FFT differential demodulation unit 14a, a selective decoding unit 14b, a deinterleave unit 1
4c, and a synchronization processor 14d. The FFT differential demodulation unit 14a performs an FFT process and a differential decoding process on the digital data I (m) and Q (m) output from the AD converter 13 to demodulate the interleaved transmission data.
The deinterleave 14c deinterleaves the output data of the FFT differential demodulation unit to return to the original data sequence, and the selective decoding unit 14b performs error detection and correction processing on the deinterleaved data, and the contents of the high-speed information channel unit FIC. Is input to the control unit 17. The control unit 17 detects the symbol position of the service (program) specified by the user based on the service arrangement data included in the high-speed information channel unit FIC, and notifies the selective decoding unit 14b. Selective decoding unit 1
4b outputs decoded data (MPEG audio data) of the notified symbol to the audio decoding unit 15.
The audio decoding unit 15 converts the input MPEG audio data into the original PCM audio data and outputs it. In addition, the control unit 17 sends the label (program name) included in the high-speed information channel FIC to the operation unit as appropriate in response to a user request, and displays the label.

The synchronization processor 14d performs an FFT process on the synchronization symbol after detecting the null symbol, calculates a frequency offset of the input signal, and converts the AFC signal into a quadrature demodulator 12d.
b to adjust the reference frequency. Further, the synchronization processor 14d calculates the correlation (shift amount) between the FFT result of the synchronization symbol and the original synchronization symbol, and compares the result with the inverse FFT.
FT processing and transmission path impulse response CIR (channel I
mpulse Response) is output. FFT differential demodulation unit 14a
Uses this CIR signal when creating an FFT window signal. When synchronization is impossible (for example, when a null symbol cannot be detected), the synchronization processor inputs a high-level signal SYN to the control unit 17.

(B) Frequency reception history FIG. 2 is an explanatory diagram of the frequency reception history stored in the frequency reception history storage unit 21. The frequency reception history storage unit 21 can store frequency information FCI of n types of DAB broadcast signals received most recently, and each frequency information FCI includes a DAB broadcast frequency, a DAB transmission mode (DAB transmission format). This mode includes modes I, II, III, and IV) and has an update time. First, all DAB broadcast signal frequencies that can be received by the DAB receiver are searched and stored in the frequency reception history storage unit 21. Thereafter, if a DAB signal different from the frequency of the DAB signal received so far is received, the frequency reception history information (frequency information) is updated or additionally stored.
That is, when a DAB signal having the same frequency as the frequency stored in the frequency reception history storage unit 21 is received,
When the update time is rewritten with the current time by the update process, and a DAB signal having a frequency different from the frequency stored in the frequency reception history storage unit 21 is received, frequency information is newly created and stored for the frequency. NO. 1, NO2
In the order of..., For example, if they are arranged in the order of frequency, the operation can be performed without discomfort similarly to the conventional FM / AM radio. When the storage area becomes full, the oldest frequency information is deleted using data indicating the update time, and new frequency information is entered. Therefore, DABs are stored in order of the frequency stored in the frequency reception history storage unit 21.
If the frequency is sought, the DAB broadcast being broadcast can be easily received, and a desired program can be received.

(C) DAB Frequency Search Process FIG. 3 is a flowchart of a DAB frequency search process according to the present invention.
The seek is performed from the lower frequency to the higher frequency, and after reaching the highest frequency, the seek is performed from the lowest frequency. First, it is checked whether or not the user has instructed reception of another DAB broadcast signal (seek selection) by operating the seek key SK (step 101). If seek tuning has not been instructed, it is checked whether the search key FLSK has been operated (step 102). If not, return to the beginning.

On the other hand, if the search key FLSK is operated, the first frequency is loaded from the frequency block table 22 (step 103), and the PLL circuit 12a-2 is set to the frequency to receive the DAB broadcast signal of the frequency. Oscillation is performed at the corresponding local oscillation frequency (step 104). Next, it is checked whether the DAB signal has been detected (step 105). That is, the reception electric field intensity E output from the reception electric field intensity detection unit 19 is measured, and it is checked whether the reception electric field intensity E is equal to or higher than the set level Es. If E ≧ Es, synchronization control is performed by the synchronization processor 14d, and it is checked whether synchronization has been achieved by referring to the output signal SYN.
If K, it is determined that "the DAB signal has been detected". However, if E <Es or if synchronization is not achieved, "DAB
No signal can be detected ".

If the DAB signal can be detected, it is checked whether the DAB signal frequency is stored in the frequency reception history storage unit 21, and if it is stored, the update time is rewritten with the current time. However, if it is not stored, the frequency information (frequency / transmission mode / update time) is written in an empty area of the frequency reception history storage unit 21. In this case, if there is no vacant area, the oldest frequency information stored in the frequency reception history storage unit 21 is searched, and the new frequency information is written thereon (step 106). Thereafter, or if the DAB signal cannot be detected in step 105, it is checked whether the next frequency remains in the frequency block table 22 (step 10).
7) If present, the PLL circuit 12a-2 oscillates at a local oscillation frequency corresponding to the next frequency in order to receive the DAB broadcast signal of the next frequency (step 108).
The processing after 05 is repeated. If the above processing continues and the frequency does not remain in the frequency block table 22,
The completion of the search process is displayed on the display 18a (step 1).
09). As described above, the receivable DAB signal frequencies are stored in the frequency reception history storage unit 21.

In step 101, when a seek channel selection operation is performed, it is checked whether or not a frequency reception history (frequency information) FCI exists in the frequency reception history storage unit 21 (step 111). Possible D
The fact that the AB signal frequency does not exist is displayed on the display unit 18a, and the seek operation ends (step 112). That is, seeking cannot be performed unless the frequency information FCI exists in the frequency reception history storage unit 21. Therefore, it is necessary to cause the frequency reception history storage unit 21 to hold the frequency information by the search operation. If the frequency information exists in step 111, a frequency higher than the current reception frequency of the DAB receiver and closest to the current reception frequency is obtained from the frequency information, and the DAB signal of the obtained frequency can be received. Then, the local oscillation frequency is controlled (step 113).

Next, it is checked whether the DAB signal has been detected (step 114). If the DAB signal can be detected, the frequency information (frequency /
(Transmission mode / reception time) is updated to complete seek selection (step 115), and waits for the next user operation. If the user is not satisfied with the program selected by the seek operation, the seek operation is performed again, so that the processing from step 101 onward is repeated. However, if the user is satisfied with the program selected by seeking, the user will continue to listen to the program. Step 1
If the DAB signal cannot be detected in 14, it is checked whether the next frequency information (frequency) exists in the frequency reception history storage unit 21 (step 116). The local oscillation frequency is controlled so as to be possible (step 117), and the process returns to step 114 to repeat the subsequent processing.

If the DAB signal can be detected, the frequency information (frequency / transmission mode / reception time) in the frequency reception history storage unit 21 is updated (step 115), and the next user operation is waited. However, if the DAB signal cannot be detected, the process of step 116 is repeated. If the next frequency information (frequency) does not exist in the frequency reception history storage unit 21 because the DAB signal cannot be detected, the process of step 112 is repeated to end the seek. That is, if the DAB signal cannot be detected even after one round, the seek ends. This means that the frequency information (frequency / transmission mode / reception time) in the frequency reception history storage unit 21 becomes obsolete and unusable. Therefore, it is necessary to appropriately update the frequency information in the frequency reception history storage unit 21 by a search.

(D) Modification 1 As described above, in order to prevent the frequency information in the frequency reception history storage unit 21 from becoming obsolete, the DAB is not received (for example, CD / cassette tape / FM / AM). When the user is listening to the radio), the frequency of all DAB broadcasts that can be automatically received in the background is searched, and the frequency information in the frequency reception history storage unit 21 is updated based on the search result. . That is, when an audio source other than DAB such as a CD player, a cassette tape, and an FM / AM radio is selected, the processing of steps 103 to 108 in FIG. 3 is automatically performed.

(E) Modification 2 When a search key FLSK is operated to perform a frequency search for a receivable DAB signal, if the frequency search is performed frequently, the audio of the DAB broadcast cannot be output during that time. If a search is not performed, the frequency information in the frequency reception history storage unit 21 becomes obsolete, and seek tuning cannot be performed properly.
Therefore, it is convenient if the user can be notified of the frequency search timing. Data included in the high-speed information channel FIC of the DAB broadcast signal (area-specific broadcast station information)
Is used, the region where the vehicle is located (Region) can be obtained. If the area obtained from the regional broadcasting station information is different,
The frequency of the receivable DAB broadcast signal is also different. Therefore,
The fact that the vehicle has entered another area is detected using the regional broadcasting station information, and a frequency search is instructed at the time of the detection.

(E-1) Regional Broadcast Station Information FIG. 4 is a processing flow of generating a frequency search start signal according to the present invention, and FIG. 5 is an explanatory diagram of regional broadcast station information included in the high-speed information channel FIC. The regional broadcasting station information is inserted into the data field specified by FIG. 0/11 as shown in FIG. 5, and a plurality of regional identification information (Region Identificatio) 301, 30
2, ..., 303. Each region identification information 301-303,
GATy (Geographical Area Type) 311, region identifier
(RegionId) 312, with Geographical Area information 313,
Geographical Area information 313 contains multiple Transmitter Groups
321 to 324. Each Transmitter Group 321-32
4 is the transmitter group identifier (MainId) 331, Su
It consists of bIdlist length 332, SubId list 333,
d list 333 contains multiple transmitter sub-identifiers (SubId)
341-342 are included. From the above, by referring to the data field of FIG 0/11, (MainId + S of all transmitters belonging to the region specified by Region
ubId).

On the other hand, in DAB broadcasting, MainId and SubId of a transmitter can be recognized from null period information of a DAB broadcasting signal. Therefore, the DAB signal is received, and the MainId and SubId of the DAB signal transmitter (DAB broadcasting station) are recognized from the null period information,
Thereafter, the DAB signal is included in the high-speed information channel FIC.
MainId and SubId recognized from 11 data fields
If the region identifier RegionId having
RegionId is the region to which the DAB receiver (vehicle) currently belongs to
will indicate on.

(E-2) Processing for Generating Frequency Search Start Signal The MainId and SubId of the DAB signal transmitter (DAB broadcasting station) are recognized from the null period information of the currently received DAB signal (step 201). Next, the high-speed information channel FIC
The broadcast station information by area is obtained from the broadcast station information (step 202), and the area to which the current vehicle belongs (reigion) is obtained from the broadcast station information by area.
A region identifier (RegionId) is obtained (step 203).
Next, it is checked whether or not it matches the Region Id held up to that time (step 204). If they match,
Returning to the beginning, the subsequent processing is repeated. If they do not match, a signal instructing the start of frequency search is generated, the display lamp on the display unit is turned on (step 205), and the Region Id held in the current area is updated. (Step 206), and thereafter, return to the beginning and repeat the subsequent processing. The user knows the timing to perform the frequency search by turning on the lamp, and operates the search key FLSK in a timely manner so that D can be received.
Searches the frequency of the AB signal and stores the frequency reception history storage unit 2
Update the contents of 1. As described above, the present invention has been described with reference to the embodiments. However, the present invention can be variously modified in accordance with the gist of the present invention described in the claims, and the present invention does not exclude these.

[0033]

As described above, according to the present invention, all receivable DAs
The frequency of the B signal is searched and stored, and the DAB signal is tuned to the stored frequency by the tuning operation of the DAB signal so that the DAB signal is received. In addition, the time required for selecting a desired program can be reduced. According to the present invention, an area where a vehicle is located is determined using data included in a high-speed information channel of a received DAB broadcast signal, and when a vehicle enters another area, a frequency search for all receivable DAB signals is instructed. Since the output signal is output, the user can be notified of the frequency search timing. As a result, the frequency search can be performed in a timely manner, so that the frequency search is not performed frequently, the time for outputting the DAB broadcast sound can be extended, and the frequency information does not become obsolete. The DAB signal can be sought and received.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a DAB receiver of the present invention.

FIG. 2 is an explanatory diagram of a frequency reception history.

FIG. 3 is a flowchart showing a DAB frequency search method algorithm of the present invention.

FIG. 4 is a processing flow of generating a frequency search start signal according to the present invention.

FIG. 5 is an explanatory diagram of regional broadcast station information in a high-speed information channel FIC.

FIG. 6 is an explanatory diagram of a frame structure of a DAB broadcast signal.

FIG. 7 is a configuration diagram of a DAB transmitter.

FIG. 8 is a configuration diagram of a conventional DAB receiver.

FIG. 9 is a processing flow of a conventional seek channel selection.

FIG. 10 is an explanatory diagram of a conventional channel selection operation.

[Explanation of symbols]

 12. RF signal demodulation unit for DAB 14. Transmission line decoding circuit 17 Control unit 19 Received electric field strength detection unit 21 Frequency reception history storage unit 22 Frequency block table SK Seek key FLSK・ Frequency list search key

Claims (2)

[Claims] 1. A method for receiving a DAB signal having a received electric field strength equal to or higher than a set value, wherein the DAB receiver searches for and stores the frequency of a receivable DAB signal, and stores the frequency by selecting a DAB signal. Receiving a DAB signal in synchronization with a predetermined frequency.
B signal receiving method. 2. An area in which a vehicle is located using data included in a high-speed information channel of a DAB broadcast signal during reception, and when the vehicle enters another area, all DAs that can be received are obtained.
2. The DAB signal receiving method according to claim 1, wherein a signal instructing a frequency search of the B signal is output.