JP2531714B2 - Method for discriminating station frequency data transmission method in radio data system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method of determining a transmission method of station frequency data in a radio data system.

Background Art When a program is broadcast by a general broadcasting station, information related to the program content is transmitted as data by multiplex modulation, and the desired program content can be selected based on the demodulated data on the receiving side so that a radio listener can select it. There is a radio data system (RDS) that makes it possible to provide that service to.

In this radio data system, 57 kHz, which is the third harmonic of the 19 KHz stereo pilot signal 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 content, and the amplitude-modulated sub-carrier is frequency-modulated to a main carrier for broadcasting.

As is clear from FIG. 3 showing the baseband coding structure of the radio data signal, 104 bits are repeatedly multiplexed in a group of 104 bits. 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. 3, block 1 is a program recognition (PI) code, block 2 is a traffic program identification (TP) code, and block 3 is a station frequency (AF) data of a network station broadcasting the same program. However, in block 4, program service name information (PS) such as broadcasting 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 AF data of the network station is supposed to be transmitted only in the type 0A group.

In this way, the type 0A group radio data also includes AF data of network stations that are broadcasting the same program as the currently receiving broadcast station, and AF data obtained by demodulation during reception If the reception sensitivity of the broadcasting station currently being received decreases due to disturbance such as a decrease in electric field strength, another network station can be selected based on the AF data of the network station stored in advance. By broadcasting, the same program can always be listened to 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. 4 (A), the AF data (f _{1 to} f _n ) of the network stations broadcasting the same program can be received for up to 25 stations regardless of whether or not they 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 method, AF data (f _{1 to} f _n ) of network stations broadcasting the same program are grouped for each network station within a receivable area with that station as the central station. As shown in FIG. 4 (B), a block group is obtained for each group in which the AF data for two stations, each pair consisting of the central station and another station in the group, are obtained and The first block of the first block is used as the number-of-stations data m _n in each group, and a plurality of block groups are repeatedly transmitted in order. 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 the block 3 in FIG. 3, and is transmitted as a 16-bit (2 × 8-bit) information word. In addition, the transmission system of A and B will be 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.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an object thereof is to provide a method for determining an AF data transmission method in a radio data system capable of reliably determining the AF data transmission method in a short time. To do.

According to the method of discriminating an AF data transmission method according to the present invention, a block group in which the AF data for two network stations broadcasting the same program are used as one block and the first data of the first block is the number of stations of the network station is obtained. A method for repeatedly transmitting the block group as data in sequence, and for each group having each network station as a central station, AF data for two stations that pair the central station with other stations in the group is defined as one block. A block B for each group is obtained, and the head data of the first block of each group is used as the number-of-stations data in each group to repeatedly transmit a plurality of block groups in sequence, and the method is obtained by demodulating a received broadcast wave. Number of stations data and AF
Data is sequentially fetched, and the current value of the station number data and its previous value are repeatedly compared and compared, and
The feature is that the determination is made by performing coincidence comparison between the AF data and one of the pair of AF data obtained in the next block.

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

FIG. 1 is a block diagram showing an outline of a basic configuration of an RDS receiver to which an AF data transmission system discrimination method according to the present invention is applied. In the figure, received by antenna 1
A desired station is selected by the front end 2 from the FM multiplex broadcast wave, converted into an intermediate frequency (IF), and then supplied to the FM detector 4 via the 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, the detection output of the FM detector 4 passes through the filter 6, so that the 57 KHz subcarrier amplitude-modulated by the biphase-coded data signal, that is, the radio data signal is extracted and demodulated by the PLL circuit 7. . This demodulated output is the digital (D) PLL circuit 8 and the decoder 9.
Is supplied to. The D-PLL circuit 8 generates a data demodulation clock based on the demodulation 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 is locked, generates a lock detection signal, supplies the lock detection signal to the gate circuit 10, and controls the circuit 10 to be in an open state. In the decoder 9, the bi-phase coded data signal which is the demodulated output of the PLL circuit 7 is decoded in synchronization with the clock generated in the D-PLL circuit 8.

The output data of the decoder 9 is 26bi as shown in FIG.
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. In the group / broke synchronization & error detection circuit 12, the group and block are synchronized based on the 10-bit offset word assigned to the 10-bit check word of each block, and the error of the 16-bit information word is generated 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 composed of a microcomputer, and takes in code information of each block in the radio data sequentially input in units of groups, that is, information related to the program contents of the broadcasting station currently being received, and 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
IF signal level in amplifier 3 is above a certain level and
The station detection signal from the station detection circuit 17 which detects the receiving station when the detection output of the so-called S curve characteristic in the FM detector 4 is within a predetermined level range is also supplied.
When this station detection signal does not exist, 14 indicates that the receiving condition of the broadcasting station currently being received has deteriorated, and should select another network station based on the AF data of the network station stored in the memory 15 in advance. The operation of controlling the frequency division ratio of the programmable frequency divider is also performed.

Next, the procedure of the AF data transmission method determination method according to the present invention executed by the processor of the controller 14,
This will be described with reference to the flowchart of FIG. It should be noted that this routine is executed when it is confirmed that the input group is the type 0A based on the group type code and the version code arranged in the block 2 of the fetched radio data.

The processor first resets the M flag, the A ₁ flag and the A ₂ flag to zero (step S1). here,
The M flag is a flag indicating whether or not the station number data and the AF data of the first block (hereinafter referred to as the first AF data) are stored in memory, and the A ₁ flag is the station number data and the first AF data fetched the second time. The flag indicating whether or not it is the same as the number-of-stations data and the head AF data stored in memory, and the A ₂ flag is a flag indicating whether the captured AF data does not match the head AF data stored in memory.

After resetting each flag to zero, the processor takes in radio data (step S2), and subsequently judges whether or not the taken-in data is station number data (step S2).
3). If it is station number data, this station number data and the first AF data paired with the data are temporarily held in an accumulator or the like (steps S4, S5), and subsequently, whether the M flag is 1 or not. Is determined (step S6). If the M flag is 0, the M flag is set to 1 (step S7), the held station number data and the head AF data are stored in predetermined addresses of the memory 15 (steps S8 and S9), and then to step S2. Return.

If it is determined in step S6 that the M flag is 1, it means that the number-of-stations data and the head AF data are already stored in the memory 15, so that each data held is the second captured data, It is determined whether or not these respective data are the same as the respective data stored in the memory (steps S10 and S11). When it is determined that both match in step S10 and step S11, the A ₁ flag is set to 1 (step S12), and when it is determined that there is no match in either one of step S10 and step S11, the AF data transmission method is It is determined that it is the B system, and for example, in a group in which the receiving station currently receiving from the many AF data is the central station.
A process of selectively fetching only the AF data and storing it in the memory 15 is performed (step S13). That is, in FIG. 4 (B), the number-of-stations data (m _{1 to mn} ) representing the number of network stations forming a group rarely coincides with each other in the group, and is also the same as that of the first leading AF data. Since it is unlikely that the first AF data of the second time will match, it is possible to determine that the AF data transmission method is the B method by determining that they do not match in either step S10 or step S11.

If it is determined in step S3 that the data is not the number-of-stations data taken in, whether the M flag is 1 or not,
It is determined whether or not the A ₂ flag is 0 (steps S14 and S15). If either of them is determined to be "NO", the process returns to step S2, and if both are determined to be "YES", two captured AF data are held in an accumulator or the like (step
S16) It is determined whether the first or second AF data is the same as the first AF data stored in the memory (step S17,
S18). When it is determined that both do not match in step S17 and step S18, the A ₂ flag is set to 1 (step S1
9), if it is determined in any one of step S17 and step S18 that the AF data transmission method is B,
The system is determined (step S13). That is, as is clear from FIG. 4, in the A method (A), the same AF data does not exist in each block, and in the B method (B), the head AF data which is the central station of the group is included in the group. Since it always exists in each block, it is possible to determine that the AF data transmission method is the B method by comparing the AF data of the first block with one of the pair of AF data obtained in the next block. .

After setting the A ₁ or A ₂ flag to 1 in step S12 or S19, the process proceeds to step S20, and it is determined whether or not the A ₁ flag is 1, and further, in step S21, the A ₂ flag is set to 1.
Or not. If both the A ₁ and A ₂ flags are 1, it is determined that the AF data transmission method is the A method, and, for example, a process of sequentially fetching all the AF data and storing it in the memory 15 is performed (step S22). .

In a normal reception state, when the electric field strength is lowered or the reception state is deteriorated, the controller 14 detects that the station detection signal is not output from the station detection circuit 17, and the AF data transmission method is the A method. In case of memory beforehand
Select the AF data of the receivable network station from all the network stations stored in 15, and in the case of B method, select one of the AF data in the group that was selected and stored previously. By selecting that network station,
It is possible to continue broadcasting the same program without interrupting the broadcasting.

EFFECTS OF THE INVENTION As described above, according to the AF data transmission method determination method of the present invention, the number-of-stations data obtained by demodulation and
By sequentially fetching the AF data and comparing the current value of the number of stations data with its previous value repeatedly, and by comparing the AF data of the first block with either of the pair of AF data obtained in the next block. Since it is possible to determine whether the AF data transmission method is the A method or the B method according to the captured block, the determination processing can be reliably performed in a short time while capturing the data.

[Brief description of drawings]

FIG. 1 is a block diagram showing an outline of a basic configuration of an RDS receiver to which the method for discriminating an AF data transmission method according to the present invention is applied, and FIG. 2 is a block diagram showing an AF data transmission method according to the present invention executed by a processor. FIG. 3 is a flow chart showing the procedure of the discrimination method, FIG. 3 is a diagram showing the baseband coding structure of radio data, and FIG. 4 is a diagram showing an array of paired AF data according to the transmission method of AF data. Method A and method (B) indicate method B, respectively. Explanation of symbols of main parts 2 ... Front end, 4 ... FM detector 5 ... Multiplex demodulation circuit 8 ... Digital PLL circuit 9 ... Decoder, 14 ... Controller 17 ... Station detection circuit

Claims (1)

(57) [Claims] 1. A block group in which station frequency data of two network stations broadcasting the same program is defined as one block, and the head data of the first block is used as station number data of the network station to select the block group. A first transmission method in which transmission is repeatedly performed in order, and for each group in which each of the network stations is a central station, the station frequency data for two stations that pair the central station with other stations in the group is one block Of the first block of each group and the second transmission method of sequentially transmitting a plurality of block groups with the head data of the first block of each group as the station number data in each group. Therefore, the station number data and the station frequency data obtained by demodulating the received broadcast wave are sequentially captured, and the current value and the previous value of the station number data are repeated. Then, by performing coincidence comparison and performing coincidence comparison between the station frequency data of the first block and one of the pair of station frequency data obtained in the next block, the transmission method of the station frequency data is the first transmission method. A method for discriminating a station frequency data transmission method in a radio data system, characterized in that it is discriminated whether it is the second transmission method.