JPH03227131A - Reception frequency selecting method in rds receiver - Google Patents

Abstract

PURPOSE:To return a receiving station to a station within a desired area even when a same network station at the outside of a desired area is received in a regional OFF mode by storing a PI data and an AF data of a current receiving station and applying a prescribed processing. CONSTITUTION:A processor of a controller 13 stores a PI data and an AF data of a current receiving station into a memory 14. Then the processor detects the presence of the receiving station by monitoring a station detection signal from a station detection circuit 17. When the PI data obtained from a detected broadcast wave of the receiving station is coincident with the PI data stored precedingly except an area code, the frequency of the receiving station is used as a new reception frequency. When a command from an operation section 13 is received, the processor restores the frequency to the original reception frequency given in terms of the AF data stored precedingly. Thus, even when a same network station at the outside of a desired area is received in the regional OFF mode, the receiving station is restored to a station within a desired area.

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 (Bipha).
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 Figure 3, 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. 4(a) and 4(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 (P
Block 3 contains station frequency data (TY) code of network stations broadcasting the same program.
In the block 4, broadcasting station name data (hereinafter referred to as Ps data) is arranged. 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 is transmitted in the PSS pig type OA and OB group.

In this way, the radio pig signal of the type OA group 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 obtained by demodulation and P
Import the I data and store it as an AF list.
For example, if the reception sensitivity of the broadcasting station currently being received decreases due to disturbances such as multipath interference, the AF
The so-called network follow (PI check), which selects other stations in the same network station group based on the list and further compares PI data, confirms whether the program received according to the AF list is correct.
Network Follow) function allows you to always listen to the same program with good reception without being affected by disturbances.

Since there are stations on the same network with different area codes in their PI data, this network follow function has two modes: a regional OFF mode that ignores area codes during PI checks, and a PI check that includes area codes. There is a regional ON mode that performs the following.

In regional OFF mode, the same network station may be received outside the area where the first receiving station exists.

By the way, if you want to limit network follow to the same network stations within the area where the first receiving station exists, but due to an operational error etc., you specify the local OFF mode and end up receiving stations outside the desired area. When a user wishes to limit the receiving stations to stations within a desired area, the conventional network follow function cannot return the receiving stations to stations within the desired area, which is inconvenient.

Summary of the invention [Object of the invention] Therefore, the present invention provides an RDS receiver that can return the receiving station to a station within the desired area even when receiving the same network station outside the desired area in regional OFF mode. The purpose of this invention is to provide a receiving frequency selection method.

[Structure of the Invention] The receiving frequency selection method according to the present invention is performed by selecting the received frequency from the current receiving frequency in an RDS receiver capable of receiving RDS broadcast waves on which multiple AF data of the same network station group and PI data including area codes are superimposed. One of multiple AF data
This is a reception frequency selection method for switching the reception frequency to another same network station frequency given by In the second step of detecting the presence of the receiving station, when the PI data obtained from the broadcast waves of the receiving station detected in the second step and the PI data held in the first step match except for the area code, this receiving station The third step is to set the frequency as the new reception frequency, and the fourth step is to return the reception frequency to the current reception frequency given by the AF data held in the first step in response to a command.

[Operation of the invention] In the reception frequency selection method according to the invention, the AF data of the first reception station is held in advance, and the AF data of the first reception station is stored in advance.
When a station outside the area of the first receiving station is received by performing network follow in FF mode, the AF pre-holds the receiving frequency in response to a command.
Return to the original reception frequency given by the data.

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 is, 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 10 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. 3, 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.

As mentioned earlier, the network follow function has two modes: a regional OFF mode in which the area code is ignored during the PI check, and a regional ON mode in which the PI check is performed including the area code. 15 by the user.

Also, 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 curve in the FM detector 4 when the F signal level in the IF amplifier 3 is equal to or higher than a predetermined level. A station detection circuit 17 that detects a receiving station and outputs a station detection signal when the detected output of the characteristic is within a predetermined level range is provided, and the station detection circuit 17 detects the reception signal level detected by the level detection circuit 16 and the station detection circuit. The station detection signal output from 17 is supplied to controller 13.

Next, the processing procedure of the network follow function executed by the processor of the controller 13 will be explained according to the flowchart of FIG. Note that in this example, the regional OFF button is set in advance on the operation unit 15.
mode is specified, and this specification allows regional ON
Assume that the flag has been reset. Further, it is assumed that the memory 14 has already taken in AF data obtained by demodulating received broadcast waves, and has already created an AF list of stations on the same network as the broadcast station currently being received.

First, the processor takes in the AF data and PM data of the broadcast wave currently being received, stores them in a predetermined area of the memory 14 (Step S1), and reads out the AFL-1 in the list from the memory 14 according to the previous AF list. (Step S2), then the muting circuit 18 is turned on to mute the audio (Step S3), and then the read AF data is input to the PL in the front end 2.
The signal is output to the L circuit (not shown) (step S4), and at the same time, a PLL timer is set for the time T1 required for the PLL circuit to lock (step $5). The AF data supplied to the PLL circuit is set in a programmable frequency divider within the PLL circuit, and the reception frequency changes from the current reception frequency to another network station frequency during a period until the PLL timer times up.

After the PLL timer times up (step S6), 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. If so, the received signal level of the network station currently being received is fetched from the level detection circuit 16 (step S8), and it is determined whether this received signal level is equal to or higher than a predetermined set level Vs (step S9). If it is equal to or higher than the set level Vs, the processor takes in the PI data of the receiving station (step 510), and then determines whether the previous regional ON flag is set (step 511). Since the regional OFF mode has been specified in advance, the regional ON flag has been reset, and therefore the processor checks whether the imported PI data and the PI data held in step S1 match except for the area code. If they match (step 812a), the muting circuit 18 is turned off to cancel the audio mute (step 813). As a result, the network station frequency currently being received becomes the new reception frequency.

Note that in the regional ON mode in which the regional ON flag is set, the processor determines whether the captured PI data and the PI data held in step S1 match, including the area code (step 512b). If they match, the process moves to step S19 and audio muting is canceled.

If it is determined in step S7 that there is no receiving station, if it is determined in step S9 that the received signal level is less than the set level VS, or in step 512a,
If it is determined in step 512b that the PI data do not match, the processor determines whether or not the processing of checking the existence of a receiving station, checking the received signal level, and comparing the PI data for all AF lists has been completed. (step 514), if not completed, step S2
Return to and repeat the process described above. When the processing is completed for all of the AF list, the processor executes step S1.
Step 515: Read the original AF data held in
), mute the audio (step 516), and then output the read AF data to the PLL circuit (step 5).
17), and simultaneously set the PLL timer (step 518). Then, after the PLL timer times up (
Step 518), and cancel the audio mute (Step 519). This means that the receiving frequency has returned to the original frequency of the receiving station.

The above is a normal network follow function, but in the present invention, the following functions are further added. After canceling the mute in step 313, the processor sets a return timer for a certain period of time T2 (step 520), and issues a return command from the operation unit 15, for example, by key operation by the user, within the certain period of time T2 until the timer times up. (Step S21, 522). If a return command is not issued before time-up, the processor immediately ends the processing of this routine, and if a return command is issued, the processor cancels the audio mute (step 823) and returns to the previous regional Set the ON flag (step 524), then step S15
to move to.

That is, in the regional OFF mode, when a station outside the area where the first receiving station exists is received by network follow, if within a certain period T2, the user issues a return command from the operation unit 15. Since the AF data of the receiving station before network follow is called, the receiving frequency can be returned to the initial receiving frequency.

With the addition of this function, for example, if you want to limit network follow to the same network stations in the area where the first receiving station exists, but due to an operational error, you specify regional OFF mode and receive stations outside the desired area. If you wish to return the receiving station to a station within the original area, you can automatically return to the original receiving station by issuing a return command. Also, at this time, in step S24, the regional ON
By setting the flag, the regional ON mode is automatically designated, so that from now on, network following is limited to the same network stations within the area where the original receiving station exists.

As described in detail, in the receiving frequency selection method according to the present invention, the AF data of the first receiving station is held in advance, and the presence of the first receiving station is determined by performing network following in regional OFF mode. When a station outside the desired area is received, the reception frequency is returned to the original reception frequency given by the pre-held AF data in response to a command, and the same network station outside the desired area is activated in regional OFF mode. Even if a signal is received, the receiving station can be returned to a station within the desired area.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the basic configuration of an RDS receiver to which the reception frequency selection method according to the invention is applied, and FIG. 2 shows an example of the processing procedure of the network follow function, which is the reception frequency selection method according to the invention. Flowchart showing,
Figure 3 shows the baseband coding structure of Radio Pig, and Figure 4 shows group types OA (a) and OB.
It is a figure which shows the format of (b). Explanation of symbols of main parts 2...Front end 4...F
M detector 5...Multiplex demodulation circuit 8...
...Digital PLL circuit

Claims (3)

[Claims] (1) RDS in which multiple frequency data of the same network station group and program identification data including area code are superimposed
A reception frequency selection method for switching the reception frequency from the current reception frequency to another same network station frequency given by one of the plurality of frequency data in an RDS receiver capable of receiving broadcast waves, the method comprising: A first step of holding frequency data and program identification data obtained by demodulating the data, a second step of detecting the presence of a receiving station, and program identification data obtained from the broadcast waves of the receiving station detected in the second step. and the program identification data held in the first step, except for the area code, the frequency of this receiving station is set as the new receiving frequency; and in response to the command, the receiving frequency is set as the new receiving frequency. A receiving frequency selection method comprising a fourth step of returning to the current receiving frequency given by the frequency data held in the step. (2) The reception frequency selection method according to claim 1, wherein the fourth step is executable only within a certain period of time after the end of the third step. (3) The reception frequency selection method according to claim 1, wherein after the fourth step is executed, in the third step, a match comparison of program identification data including the area code is performed.