JP2596560B2 - Selective storage method of network station information in radio data system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for selectively storing network station information in a radio data system.

2. Description of the Related Art At the time of program broadcasting of a general broadcasting station, information related to the program content is transmitted as data by multiplex modulation, and a desired program content can be selected based on data demodulated on a receiving side so that a radio listener can be selected. There is a radio data system (RDS) that makes it possible to provide such services.

In this radio data system, 57 KHz which is the third high frequency of the stereo pilot signal of 19 KHz outside the frequency band of the FM modulation wave is used as a subcarrier, and the subcarrier is filtered and biphase-coded. A radio data signal is amplitude-modulated by a data signal related to the subcarrier, and the amplitude-modulated subcarrier is frequency-modulated to a main carrier for broadcasting.

As is apparent from FIG. 4 showing the baseband coding structure, the radio data signal is repeatedly multiplex-transmitted with 104 bits as one group. One group is composed of four blocks each having a 26-bit configuration, and each block is composed of a 16-bit information word and a 10-bit check word. In FIG. 4, block 1 is a program recognition (PI) code, block 2 is a traffic number organization (TP) code, and block 3 is a station frequency (AF) of a network station broadcasting the same program. The code is in block 4, and program service name information (PS) such as broadcast station name and network name
Data is arranged respectively. In addition, each group is classified into 16 types of types 0 to 15 by 4 bits according to the contents, and each type (0 to 15) has two types of A and B respectively.
One version is defined and these identification codes are located in block 2. The station frequency (hereinafter abbreviated as AF) code of the network station is to be transmitted only in the type 0A group.

As described above, the radio data of the type 0A group includes the AF data of the network station broadcasting the same program as the currently receiving broadcasting station. If the reception sensitivity of the currently receiving broadcasting station is reduced due to disturbance such as multipath interference, select another network station based on the AF data of the network station stored in advance. By doing so, the same program can always be heard in a good reception state without being affected by disturbance.

The AF data transmission method includes an A method as a first transmission method and a B method as a second transmission method. In the A-method, as shown in FIG. 5 (A), the AF data (f _{1 to} f _n ) of the network station broadcasting the same program is limited to a maximum of 25 stations regardless of whether or not it can be received. AF for 2 stations
This is a method in which a block group having data as one block is obtained, and the head data of the first block is sequentially and repeatedly transmitted as the station number data n of the network station. On the other hand, in the B system, AF data (f _{1 to} f _n ) of network stations broadcasting the same program are grouped for each network station within a receivable area centered on the station. As shown in FIG. 5 (B), for each group, a block group is obtained for each group in which AF data of two stations, each pair of a central station and another station in the group, is taken as one block. Is a method in which a plurality of block groups are sequentially and repeatedly transmitted as the first data of the first block as the station number data _mn in each group. In this B method, the arrangement order of the two AF data in each block is determined by the magnitude relationship between the frequencies of the paired stations. In both systems, the AF data consists of 8 bits, is arranged in block 3 in FIG. 4, and is transmitted as an information word of 16 bits (2 × 8 bits). The transmission method of A and B is selected on the broadcast station side.

As described above, since there are two AF data transmission methods, the demodulated AF on the receiving side is performed according to each method.
Since the data processing method is also different, it is desired to be able to quickly and reliably determine whether the AF data transmission method is the A method or the B method.

In the case of the B method, the amount of AF data is much larger than that of the A method. Of these AF data, only AF stations in a group whose central station is the currently receiving receiving station are required.
Since it is data, it is required that only desired AF data can be quickly selected and stored from many AF data.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points,
It is an object of the present invention to provide a method for selectively storing AF data in a radio data system capable of selecting and storing only desired AF data from AF data in a short time.

According to the method for selectively storing AF data according to the present invention, for each group centered on each of the network stations broadcasting the same program, the central station is paired with another station in the group.
Radio data according to a transmission method in which a block group for each group having one station of AF data as a block is obtained, and a plurality of block groups are sequentially and repeatedly transmitted as head data of the first block of each group as the number of stations in each group. In the system, AF data obtained by demodulating a received broadcast wave is sequentially taken in for each block, and is compared with reception frequency data of a currently receiving broadcast station. It is characterized in that AF data paired with the matched AF data is sequentially stored in the memory from the time when the match is detected.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram schematically showing a basic configuration of an FM multiplex broadcasting receiver to which a method for selectively storing AF data according to the present invention is applied. In the figure, an FM multiplex broadcast wave received by an antenna 1 is selected by a front end 2 and converted into an intermediate frequency (IF), and then supplied to an FM detector 4 via an IF amplifier 3. . The front end 2 is, for example, a PLL using a PLL circuit including a programmable frequency divider.
It adopts a synthesizer system, and performs a channel selection operation by controlling the frequency division ratio of the programmable frequency divider by a controller 14 described later. FM detector 4
Is supplied to an MPX (multiplex) demodulation circuit 5, where it is separated into L (left) and R (right) channel audio signals in the case of a stereo broadcast.

Further, when the detection output of the FM detector 4 passes through the filter 6, a 57 KHz subcarrier amplitude-modulated by the data signal coded in the back phase, that is, a radio data signal is extracted and demodulated by the PLL circuit 7. . This demodulated output is supplied to a digital (D) PLL circuit 8 and a decoder 9.
Supplied to In the D-PLL circuit 8, a clock for data demodulation is generated based on the demodulated output of the PLL circuit 7. The generated clock is supplied to the gate circuit 10. The lock detection circuit 11 detects that the D-PLL circuit 8 has locked, generates a lock detection signal, and supplies this to the gate circuit 10 to control the circuit 10 to open. The decoder 9 decodes the biphase-coded data signal, which is the demodulated output of the PLL circuit 7, in synchronization with the clock generated by the D-PLL circuit 8.

As shown in FIG. 4, the output data of the decoder 9 is 26 bi.
The unit is a 104-bit group consisting of four blocks having a t configuration, and is sequentially supplied to the group and block synchronization & error detection circuit 12. The group / block synchronization & error detection circuit 12 synchronizes the group with the block based on the 10-bit offset word assigned to the 10-bit check word of each block, and detects the error of the 16-bit information word based on the check word. Detection is performed. The error-detected data is subjected to error correction by an error correction circuit 13 at the next stage, and then the controller
Supplied to 14.

The controller 14 is constituted by a microcomputer, and fetches code information of each block in the radio data sequentially input in group units, that is, information relating to the program contents of the broadcast station currently being received, and stores it in a memory 1 such as a RAM.
5 and the frequency division ratio of a programmable frequency divider (not shown) of a PLL circuit constituting a part of the front end 2 is controlled based on a channel selection command from the operation unit 16. Perform the operation. The controller 14 also has an IF
Each detection output of the level detection circuit 17 that detects that the signal strength has decreased based on the signal level and the multipath detection circuit 18 that detects the multipath interference based on the FM detection output is also supplied. When these detection outputs are supplied, the controller 14 determines that the reception state of the currently receiving broadcast station has deteriorated, and selects another network station based on the AF data of the network station stored in the memory 15 in advance. In order to control the frequency division ratio of the programmable frequency divider, the operation is performed.

Next, a procedure of a method of determining the AF data transmission method executed by the processor of the controller 14 will be described with reference to the flowchart of FIG.

First, the processor resets a built-in data counter to zero (step S1), and then fetches radio data (step S2). Based on the group type code and version code arranged in block 2 of the fetched radio data, it is determined whether or not the input group is type 0A, that is, whether or not the radio data contains AF data. If it is determined (step S3) that the type is not Type 0A, AF data cannot be obtained, and it is not necessary to determine the AF data transmission method, so the determination operation is stopped. In the case of the type 0A group, it is determined whether or not the AF data for two stations obtained from the radio data includes station number data indicating the number of network stations broadcasting the same program, ie, FIG. (Step S4), and if the data does not include the number-of-stations data, the process returns to Step S1 to repeat the above operation.

If the station number data is not included in the AF data for the two stations, the two data are stored in the memory 15 (step S
5) Then, the data counter is counted up by "2" (step S6), and it is determined whether or not the count value N becomes N = 4, that is, whether or not two blocks and four data fetches have been completed. Judge (step S7). If N ≠ 4, the flow returns to step S2 to take in AF data until N = 4.

If N = 4, it is determined whether the first AF data and the third and fourth AF data are the same among the four data (two blocks) stored in the memory 15 (steps S8 and S8).
9) It is determined whether the second AF data is the same as the third and fourth AF data (steps S10 and S11),
If it is determined that the transmission method is different in any case, it is determined that the transmission method of the AF data is the A method, and for example, all the AF data after the fourth block are fetched and stored in the memory 15 (step S12). On the other hand, if it is determined that the AF data is the same in at least one of the steps S8 to S11, it is determined that the transmission method of the AF data is the B method. A process of selecting and storing only the AF data within the group having the receiving station as the central station is performed (step S13).

That is, as is clear from FIG. 5, the A method (A)
So, the same AF data does not exist in each block,
In the B method (B), AF data of the central station of the group always exists in each block in the group. Therefore, two blocks of data sequentially obtained from the radio data of the type 0A group are fetched and the AF data of these blocks is obtained. By performing the coincidence comparison, it is possible to reliably determine the AF data transmission method in a short time. In addition, the first including the station number data
By sequentially taking in data of two blocks excluding a block, data of two blocks belonging to the same group can always be taken in the B system, and data comparison between only two blocks can be performed. It can be done more reliably and quickly.

Subsequently, the procedure of the AF data selection and storage method according to the present invention, which is executed by the processor as a subroutine when it is determined in step S13 in FIG.
This will be described with reference to the flowchart of FIG.

First, the processor resets a built-in data counter to zero (step S21), and then fetches AF data in blocks, that is, in pairs (step S2).
2) It is determined whether or not the fetched pair AF data includes station number data indicating the number of network stations in the group (step S23).

If the paired AF data contains the number of stations data, determine whether the AF data of the central station paired with the number of stations data is the same as the reception frequency data of the currently receiving broadcast station (Step S24), if not, Step S22
Return to If they are the same, the station number data Na is stored in the built-in register (step S25), the AF data of the central station is stored in the memory 15 (step S26), and the count value N of the data counter is counted by "1". Up (Step
S27). Thereafter, the count value N of the data counter is compared with the value Na of the internal register (step S28), and N ≠ Na
If N = Na, the process returns to step S22, and the AF data selection operation ends.

On the other hand, if it is determined in step S23 that the paired AF data does not include station number data, it is determined whether one of the acquired paired AF data is the same as the reception frequency data of the currently receiving broadcast station. Judgment is made (step S29). If they are different, the process returns to step S22. If they are the same, the process proceeds to step S26 to store the paired AF data in the memory 15.

In this way, the AF data is sequentially acquired for each block, and the comparison is performed with the reception frequency data of the currently receiving broadcast station.If the comparison is made, the AF data paired with the matched AF data is sequentially stored in the memory 15. By storing, all the AF data in the group with the currently receiving broadcast station as the central station, that is, only the AF data of the receivable stations of all the network stations are selected and extracted in a short time, memory
15 will be memorable.

Also, instead of always storing from the first block of AF data, the AF data that is paired with the matched AF data is sequentially extracted and stored from the time of detection of a match, thereby preventing multipath interference. Even if the reception condition deteriorates, some AF data in the group has already been stored, so that it is possible to immediately respond to switching to another network station. If it is assumed that the AF data of the first block is always stored, for example, when the reception state deteriorates before the AF data of the first block is captured, no AF data in the group has been stored yet, Unable to select another network station,
The original function of the radio data system will be impaired.

In the reception state, when the reception state is deteriorated due to a decrease in signal strength or multipath interference, the controller 14 responds to the output of the level detection circuit 17 or the multipath detection circuit 18 to transmit the AF data. When the method is the A method, AF data of the receivable network station is selected from all the network stations stored in the memory 15 in advance, and when the method is the B method, the AF data of the group previously selected and stored is selected. By selecting one of the AF data and selecting the network station, the same program can be continuously broadcast without interrupting the broadcast.

Effect of the Invention As described above, according to the AF data selection / storage determination method of the present invention, AF data obtained by demodulation is sequentially taken in block by block to match with the reception frequency data of the currently receiving broadcast station. By performing the comparison and sequentially storing the AF data paired with the matched AF data in the memory, only the desired AF data can be selected and extracted from the many AF data in a short time.

In addition, since AF data is stored sequentially from the point when a match is detected, even if the reception condition deteriorates due to multipath interference, etc., some AF data in the group has already been stored by then, It is possible to immediately respond to switching to another network station.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an outline of a basic configuration of an FM multiplex broadcast receiver to which an AF data selection and storage method according to the present invention is applied, and FIG. 2 is a diagram showing a method of determining an AF data transmission method executed by a processor. Flow chart showing procedure, 3rd
FIG. 4 is a flowchart showing a procedure of a method for selectively storing AF data according to the present invention executed by a processor. FIG. 4 is a diagram showing a baseband coding structure of radio data. FIG. It is a figure which shows the arrangement | sequence of AF data, (A) has shown A method and (B) has shown B method, respectively. Description of Signs of Main Part 2 Front End 4 FM Detector 5 Multiplex Demodulation Circuit 8 Digital PLL Circuit 9 Decoder 14 Controller 17 Level Detection Circuit 18 Multi Path detection circuit

Claims (1)

(57) [Claims] 1. For each group centered on each of the network stations broadcasting the same program, the station frequency data of two stations, which is a pair of the center station and other stations in the group, is defined as one block. A method of selectively storing network station information in a radio data system by a transmission method in which a block group for each group is obtained and a plurality of block groups are sequentially and repeatedly transmitted as head number data in each group using head data of a first block of each group. The station frequency data obtained by demodulating the received broadcast wave is sequentially acquired for each block, and the received frequency data is compared with the received frequency data of the currently receiving broadcast station. A network in a radio data system, wherein station frequency data paired with frequency data is sequentially stored in a memory. Select a method of storing information.