JPH03227133A - Receiving frequency selecting method in rds receiver - Google Patents

Abstract

PURPOSE:To receive positively a same network station of a different regional network by storing a PI data of a current receiving station in response to a command and applying a prescribed processing when the transmission system is the B system. CONSTITUTION:A processor of a controller 13 stores a PI data of a current receiving station into a memory 14 in response to a command. Then an AF data of a block in a relation of a decreasing sequence with respect to the current receiving frequency is selected based on an AF list. The presence of another receiving station based on the selected AF data is detected by monitoring a station identification signal from a station identification circuit 17. Succeedingly, the processor uses the frequency of this receiving station as a new receiving frequency when the PI data obtained from a broadcast wave of this receiving station is coincident with the PI data stored precedingly except the area code. Thus, a same network station of a different regional network is positively received.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a radio data system receiver (hereinafter referred to as RD).
This invention relates to a reception frequency selection method in a receiver (referred to as an S receiver).

BACKGROUND TECHNOLOGY When a general broadcasting station broadcasts a program, broadcast-related information such as information related to the program content is transmitted as data using multiplex modulation, and the receiving side demodulates the data and uses the data to determine the desired program content. There is a radio data system (RDS) that allows radio listeners to select the desired service.

In this radio data system, 3 of the 19KHz stereo pilot signal is outside the frequency band of the FM modulated wave.
The next harmonic, 57 KHz, is used as a subcarrier, and this subcarrier is filtered and biphase (Blpha).
se) The radio data signal is amplitude-modulated using a data signal indicating broadcast-related information such as coded program content, and the amplitude-modulated subcarrier is frequency-modulated to the main carrier and then broadcast. The standards for this broadcasting system have been proposed by the European Broadcasting Union (EBU).

As is clear from FIG. 5, which shows the baseband coding structure of the radio data signal, 104 bits are divided into 1
Multiplex transmission is repeated as a group. A group consists of four blocks of 26 bits each, each block consisting of a 16 bit information word and a 10 bit check word. In addition, each group is classified into 16 types (0 to 15) using 4 bits according to its content, and each type (0 to 15) is classified into A
, B are defined.

FIGS. 6(a) and 6(b) show the formats of types OA and OB groups, respectively. In type OA group (a), block 1 contains 16-bit program identification data (hereinafter referred to as PI data) consisting of a country code, area code, and program code, and block 2 contains a group type code and version code. (Bo),
Traffic information broadcasting station identification (TP) code, program content identification (
Block 3 contains station frequency data (hereinafter referred to as AF data) of network stations broadcasting the same program, and block 4 contains broadcast station name data (hereinafter referred to as AF data). (abbreviated as data) are arranged respectively. On the other hand, in type OB group (b), only the contents of block 3 are different from the type OA group, and block 3 has PI data arranged therein. That is, the AF data of the network station is transmitted only in the type OA group, and the PS data is transmitted in the type QA and OB groups.

In this way, the type OA group radio data signal also includes AF data of a network station broadcasting the same program as the broadcast station currently being received. Therefore, at the time of reception, the AF data and PI data obtained by demodulation are captured and stored as an AF list, and if the reception sensitivity of the broadcasting station currently being received decreases due to disturbances such as multipath interference, for example, A who remembers
So-called Network Follow, which checks whether the program received according to the AF list is correct by selecting other stations in the same network station group based on the F list and comparing the PI data. With this function, you can always listen to the same program with good reception without being affected by disturbances.

Since there are stations on the same network that have different area codes in their PI data, this network follow function has a regional (Region I) OFF mode that ignores the area code when checking the PI, and a PI check that includes the area code. There is a regional ON mode that performs the following.

In the regional OFF mode, the same network station may be received outside the area (hereinafter referred to as regional) where the broadcast station currently being received exists.

However, apart from the same network station,
In other words, the same network in the destination region
When a user requests to actively listen to other stations, the conventional network follow function cannot respond to this request, which is inconvenient.

SUMMARY OF THE INVENTION [Object of the Invention] Accordingly, an object of the present invention is to provide a reception frequency selection method in an RDS receiver that enables active reception of the same network stations on different networks.

[Structure of the Invention] A reception frequency selection method inferior to the present invention is such that an RDS receiver capable of receiving an RDS broadcast wave on which multiple AF data of the same network station group and PI data including an area code are superimposed, selects an RDS broadcast wave. The transmission method is to transmit AF data for two stations, each group having each of the same network stations as the central station, into one pair, which is the central station and another station in the group.
When using method B, which obtains a block group for each group as a block and repeatedly transmits the plurality of block groups in order, one of the plurality of AF data in the group whose central station is the receiving station based on the frequency of the current receiving station. A reception frequency selection method for switching the reception frequency to another same network station frequency given by a second step of selecting AF data of blocks that have a relationship of decreasing sequence; a third step of detecting the presence of a receiving station based on the AF data selected in the second step; a fourth step in which the frequency of the receiving station is set as a new receiving frequency when it is detected that the PI data obtained from the broadcast wave of the receiving station matches the PI data held in the first step except for the area code; It consists of

[Operation of the invention] In the receiving frequency selection method according to the present invention, when the RDS broadcast wave transmission method is B method, the PI data of the current receiving station is held in response to a command, and the PI data of the current receiving station is held based on the AF list. Selects AF data of a block that has a decreasing numerical sequence relationship with the current receiving frequency, detects the presence of a receiving station based on the selected AF data, and holds the PI data obtained from the broadcast wave of that receiving station first. When the received PI data and the area code match, the frequency of that receiving station is set as the new receiving frequency.

Example Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 1 is a block diagram schematically showing the basic configuration of an RDS receiver to which a receiving frequency selection method according to the present invention is applied. In the figure, the FM multiplex broadcast wave received by antenna 1 is selected by a front end 2, converted to an intermediate frequency (IF), and then sent to FM via IF amplifier 3.
The signal is supplied to the detector 4. The front end 2, for example,
PLL using PLL circuit including programmable frequency divider
It adopts a single synthesizer type, and is configured to perform channel selection by controlling the frequency division ratio of a programmable frequency divider by a controller 13, which will be described later. The detection output of the FM detector 4 is supplied to an MPX (multiplex) demodulation circuit 5, and in the case of stereo broadcasting, it is output from L (left) and R (
The audio signal of the right) channel is separated and passes through the muting circuit 18 to become a reproduced audio output. The muting circuit 18 is turned on and off by the controller 13.
Off control is performed.

Further, when the detection output of the FM detector 4 passes through the filter 6, a 57 KHz subcarrier, that is, a radio data signal, amplitude modulated by the biphase coded 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. In the D-PLL circuit 8, the PLL
A clock for data demodulation is generated based on the demodulated output of the circuit 7. In the decoder 9, the biphase coded data signal which is the demodulated output of the PLL circuit 7 is
It is decoded in synchronization with the clock generated by the LL circuit 8. The lock detection circuit 1o detects the locked state and unlocked state of the D-PLL circuit 8, and switches and controls the lock ranges of the PLL circuit 7 and the D-PLL circuit 8 based on the detection output.

As shown in FIG. 5, the output data of the decoder 9 is in groups of 104 bits each consisting of 4 blocks each having a 26-bit configuration, and the data is sequentially grouped.

The signal is supplied to the block synchronization & error detection circuit 11.

The group and block synchronization & error detection circuit 11 performs group and block synchronization based on the 10-bit offset word assigned to the 10-bit check word of each block, and also performs 16-bit information based on the check word. Word error detection is performed. Then, the error-detected data is error-corrected in the next-stage error correction circuit 12, and then the controller 1
3.

The controller 13 is constituted by a microcomputer, and is configured to collect code information for each block of radio data that is sequentially input in groups, i.e., PI data, AF data, PS data, etc. related to the program content of the broadcasting station currently being received. The data information is captured and stored in the memory 14, and the frequency division ratio of a programmable frequency divider (not shown) of the PLL circuit that constitutes a part of the front end 2 is determined based on a channel selection command from the operation unit 15. Perform network follow function by controlling.

In addition, a level detection circuit 16 detects the received signal level (field strength) based on the IF signal level in the IF amplifier 3, and a so-called S A station detection circuit 17 is provided which detects a receiving station and outputs a station detection signal when the detection output of the curve characteristic is within a predetermined level range. The station detection signal output from the circuit 17 is supplied to the controller 13.

Incidentally, there are two methods for transmitting AF data: method A and method B. In method A, the AF data (f+ to fn) of network stations broadcasting the same program is transmitted for up to 25 stations, regardless of whether or not they can be received, as shown in Figure 3 (A). This is a method in which a block group is obtained in which one block contains AF data for each block, and the block group is sequentially and repeatedly transmitted using the first block's leading data as network station number data n. On the other hand, method B uses AF data (f+ to f) of network stations broadcasting the same program.
n), the network stations within the receivable area with that station as the central station are grouped for each network cycle, and the third
As shown in Figure (B), a block group is obtained for each group in which one block is the AF data of two stations pairing the central station and other stations in the group, and This is a method in which a plurality of block groups are sequentially and repeatedly transmitted using data mn for the number of stations in each group as the leading data of the block. In this B method, the arrangement order of the two AF data in each block is determined by the regional rule, and if the frequency of the front side is in a relationship with an increasing number sequence that is smaller than that of the rear side, it is the same regional, and vice versa. If the relationship is a decreasing sequence of

Note that the transmission methods A and B are selected by the broadcasting station.

In this way, since there are two AF data transmission methods, the A after demodulation on the receiving side depends on each method.
Since the F data processing method is also different, it is necessary to determine whether the AF data transmission method is A method or B method. This discrimination between A and B methods is performed by controller 1.
For example, Japanese Patent Application Laid-Open No. 1-149529
This is carried out based on the discrimination method disclosed in the publication.

Next, the processing procedure for original channel selection executed by the processor of the controller 13 when the RDS broadcast wave transmission method is the B method will be explained with reference to the flowchart of FIG. 2. Note that this routine
It is assumed that the command is called and executed when a regional channel selection command is issued by a key operation by the user. In addition, the memory 14 contains AF data obtained by receiving and demodulating RDS broadcast waves of the B method, and mainly contains an AF list of the same network stations in the group with the currently receiving broadcasting station as the center station. It is assumed that the AF data of one station and the AF data of another station have already been created as a pair.

First, the processor takes in the AF data and PI data of the broadcast wave currently being received and stores them in a predetermined area of the memory 14 (Step S1), and according to the previous AF list, converts the AF data of 1 in the list into the AF data of the central station. The AF data pair is read out from the memory 14 (step S2), and it is determined whether the arrangement relationship of the AF data pair is a decreasing sequence (step S3). If it is a decreasing sequence, the same network station based on the read AF data is a local station different from the central station, so the muting circuit 18 is turned on to mute the audio (step S4);
Then, the read AF data is output to the PLL circuit (not shown) in the front end 2 (step S5).
, At the same time, a PLL timer is set for the time T1 required for the PLL circuit to lock (step S6). PLL
The AF data supplied to the circuit is set in a programmable frequency divider in the PLL circuit, and the reception frequency changes from the current reception frequency to another network station frequency until the PLL timer times up.

After the PLL timer times up (step S7), the processor determines whether or not a receiving station exists by monitoring the output of the station detection signal from the station detection circuit 17. In step S8), the processor detects the presence of the receiving station. If so, the PI data of the receiving station is imported (step S9), and it is determined whether the imported PI data and the PI data held in step S1 match except for the area code (step 510), and if they match (step 510), In addition, it is determined whether the area code in the PI data imported this time does not match the area code in the PI data held in step S1 (step 511), and if they do not match, the muting circuit 18 is turned off. state and cancel the audio mute (step 512).

As a result, a different network station from the same network station group as the broadcasting station currently being received has been selected.

If it is determined in step S3 that the sequence is an increasing sequence,
If it is determined in step S8 that there is no receiving station, if it is determined in step S10 that the PI data does not match, or if it is determined that the area codes match in step S11, the processor reduces all of the AF list. In step 813), it is determined whether or not the processing of determining whether the sequence is a numerical sequence, checking the existence of a receiving station, comparing the PI data for coincidence excluding the area code, and comparing the area code for non-coincidence has been completed (step 813). ,
Returning to step S2, the process described above is repeated. When finished for all AF lists, the processor:
Read the original AF data held in step S1 (Step 514), then PL the read AF data.
output to the L circuit (step 515), and at the same time set the PLL timer (step 516). And PLL
After the timer times up (step 517), the process moves to step S12 to cancel the audio mute.

This means that the receiving frequency has returned to the original frequency of the receiving station. In other words, when a regional station selection command is issued to select a regional same-network station, there is no local same-network station, or the presence of a receiving station cannot be detected. If there is none, it will return to the original receiving station.

In the above embodiment, in step S2), the AF data of one of the AF soloists is read out from the memory 14 as a pair with the AF data of the central station, and it is determined whether or not the arrangement relationship of the AF data pair is in a decreasing sequence relationship. However, at the stage of creating the AF list, as shown in FIG.
21), it is determined whether or not this AF data pair is in a decreasing sequence (step 522); if it is an increasing sequence, the AF data pair is stored as is in a predetermined area of the memory 14 (step 823); In this case, a flag indicating this may be set (step 522), and then the process may proceed to step 823, where the AF data pair and this flag may be stored in a predetermined area of the memory 14 in advance. In this case, when the AF data of one of the AF soloists is read out from the memory 14 as a pair with the AF data of the center station in step S2, the previous flag is also read out, and step S2 is read out.
3, the state of the flag may be identified.

In addition, in the above embodiment, when selecting the same network station in different regions, the area code is excluded <PI
Although only the presence of a receiving station is detected (step S8) before determining whether data matches (step 510) and area codes do not match (step 511), if the presence of a receiving station is detected, the reception of that receiving station is It is also possible to import the signal level from the level detection circuit 16 and move to step S9 after detecting that the received signal level of the parenthesis is equal to or higher than the set level.

As described in detail of the invention, in the receiving frequency selection method according to the present invention, when the RDS broadcast wave transmission method is B method, the PI data of the current receiving station is held in response to a command, and the PI data of the current receiving station is held and the AF Select AF data of a block that has a decreasing numerical sequence relationship with the current receiving frequency based on the list, detect the presence of a receiving station based on the selected AF data, and PI data obtained from the broadcast wave of that receiving station. P held first
When they match except for the I data and area code, by setting the frequency of that receiving station as the new receiving frequency, it becomes possible to actively receive the same network station in a different region in a short time.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the basic configuration of an RDS receiver to which the receiving frequency selection method according to the present invention is applied, and FIG. 2 shows an example of the processing procedure for regional tuning, which is the receiving frequency selection method according to the present invention. FIG. 3 is a diagram showing the arrangement of seven pairs of AF data according to the AF data transmission method, (A) shows the A method, (B) shows the B method, and FIG. A in a modification of the present invention
A flowchart showing the processing procedure of a subroutine when creating an F list, Figure 5 is a diagram showing the baseband coding structure of radio data, and Figure 6 is a diagram showing the group type OA (
It is a figure which shows the format of a) and OB (b). Explanation of symbols of main parts 2...Front end 4.Old...F M
Detection tM5...Multiplex demodulation circuit 8...
...Digital PLL circuit

Claims (2)

[Claims] (1) RDS in which multiple frequency data of the same network station group and program identification data including area code are superimposed
In an RDS receiver capable of receiving broadcast waves, the RDS
The broadcast wave transmission method is a block group for each group in which each group has each of the same network stations as the center station, and one block is the frequency data of two stations pairing the center station and other stations in the group. When using a method in which multiple block groups are repeatedly transmitted in order based on the frequency of the current receiving station, reception is performed from the frequency of the current receiving station to the frequency of another same network station given by 1 of the multiple frequency data in the group with the receiving station as the center station. A reception frequency selection method for switching frequencies, which includes a first step of retaining program identification data obtained from broadcast waves of the current reception frequency in response to a command, and a step of retaining program identification data obtained from a broadcast wave of the current reception frequency, and a step of retaining program identification data obtained from a broadcast wave of the current reception frequency. a second step of selecting frequency data; a third step of detecting the presence of a receiving station based on the frequency data selected in the second step; and program identification obtained from the broadcast waves of the receiving station detected in the third step. Receiving characterized by comprising a fourth step of setting the frequency of the receiving station as a new reception frequency when it is detected that the data matches the program identification data held in the first step except for the area code. Frequency selection method. (2) When it is detected that the area code in the program identification data obtained in the fourth step does not match the area code in the program identification data held in the first step, the frequency of that receiving station is newly received. 2. The reception frequency selection method according to claim 1, further comprising a fifth step of determining the frequency.