JP2583541B2 - Control method in radio data receiver - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a radio data system receiver (hereinafter referred to as RD).
S receiver).

BACKGROUND ART When a broadcast station broadcasts, broadcast-related information such as information related to the program content is transmitted as data by multiplex modulation, and a desired program content can be selected on the receiving side based on the demodulated data. Radio data system (RD)
S) there.

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 modulated wave is used as a subcarrier, and the subcarrier is filtered and bi-phase coded. Etc., is amplitude-modulated by a data signal indicating information related to broadcasting to generate a radio data signal, and the amplitude-modulated subcarrier 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 correspond to 1 bit.
It is repeatedly multiplexed and transmitted as a 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 broadcasts program recognition (PI) data representing a network, block 2 broadcasts traffic program recognition (TP) data and traffic announcement recognition (TA) data, and block 3 broadcasts the same program. In the block 4, the frequency (AF) data of the group of network stations is arranged, and in the block 4, program service name information (PS) data such as a broadcast station name and a network name are arranged. In addition, each group has 4 bits of type 0 to 15 according to its contents.
There are 16 different types, and two versions of A and B are defined for each type (0 to 15). These recognition codes are arranged in block 2. In addition,
The AF data of the network station is transmitted only by the type OA group.

By the way, in the case of an in-vehicle receiver, the reception state of the broadcast wave being received may deteriorate as the vehicle travels. However, in the case of RDS broadcasting, as described above, 1
When two RDS broadcast waves are received, AF data of a group of network stations broadcasting the same program can be obtained. Monitor the received signal level (reception electric field strength), and when this level falls below the set level, By utilizing the AF data, it is possible to switch the reception frequency to another same network station frequency having a higher reception signal level.

For example, in the standby state of TA interruption by TA data, a TA interruption can be performed by taking in TA data obtained by demodulating a received broadcast wave. However, modulation of a main carrier (FM carrier) by a radio data signal is performed. Since the data demodulation sensitivity is low due to the low degree, if the set level for checking the level of the received signal level is low, accurate demodulated data may not be obtained from the received broadcast wave below this set level, Therefore, there is a case where interrupt processing cannot be performed accurately.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and provides a radio data receiver capable of selecting an optimum reception frequency satisfactorily and capable of always accurately performing an interrupt process when waiting for an interrupt. The aim is to provide a method.

A control method in a radio data receiver according to the present invention is directed to a radio data receiver capable of receiving radio data broadcast waves including frequency data of the same network station group and interrupt data indicating the type of program content and having a function of following the same program. A control method in a receiver, wherein in a normal reception mode, when a reception signal level of a current reception frequency is equal to or lower than a first set level, reception is performed from the current reception frequency to another same network station frequency given by frequency data. An optimum reception frequency selecting operation for switching the frequency to select an optimum reception frequency is performed, and in a standby mode of interruption by interruption data waiting for the start of a specific program content, a second reception signal level higher than the first set level is set. It is characterized in that the optimum receiving frequency selecting operation is performed when the level is below the set level.

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

FIG. 1 shows an example of the configuration of an RDS receiver to which the control method according to the present invention is applied.
For FM multiplex broadcast wave, the desired station is selected by Front End 2,
After being converted to the intermediate frequency (IF),
It is supplied to the FM detector 4. The front end 2 adopts, for example, a PLL synthesizer method using a PLL circuit including a programmable frequency divider, and performs a channel selection operation by controlling the frequency division ratio of the programmable frequency divider by a controller 14 described later. Has become. The detection output of the 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, and reproduced via a function switching circuit 19. Audio output. The function switching circuit 19 is the MPX demodulation circuit 5 or, for example, the tape player 2
The audio signal from 0 is selectively output, and its switching control is performed by the controller 14.

When the detection output of the FM detector 4 passes through the filter 6, a 57 KHz subcarrier amplitude-modulated by the biphase-coded data signal, 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. 3, the output data of the decoder 9 is in units of 104 bits consisting of four blocks each having a 26-bit 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 obtains 10-bit information based on the check word. Word error detection is performed. Then, the error-detected data is supplied to the controller 14 after the error is corrected by the error correction circuit 13 at the next stage.

The controller 14 is constituted by a microcomputer, and the code information of each block in the radio data sequentially inputted in the group unit, that is, the radio data information (the PI data and the AF data described above) related to the program contents of the broadcasting station currently being received. , PS data, etc.) and stores them in the memory 15. Based on a channel selection command from the operation unit 16, a programmable frequency divider (not shown) of the PLL circuit which constitutes a part of the front end 2. The channel selection operation is performed by determining the frequency ratio and controlling the reception frequency data value.

Further, a level detection circuit 17 for detecting a reception signal level (electric field strength) based on the IF signal level in the IF amplifier 3.
And a station detection circuit for detecting a receiving station and outputting a station detection signal when the IF signal level in the IF amplifier 3 is equal to or higher than a predetermined level and the detection output of so-called S curve characteristics in the FM detector 4 is within a predetermined level range. 18 and is provided,
The received signal level detected by the level detection circuit 17 and the station detection signal output from the station detection circuit 18 are supplied to the controller 14.

Next, the procedure of the control method according to the present invention executed by the processor of the controller 14 will be described with reference to the flowchart shown in FIG. Note that AF data obtained by demodulating the received broadcast wave is taken into the memory 15 and AF data lists f ₁ , f _2, ... F _{n of the} same network station as the currently receiving broadcast station have already been created. Shall be

The processor first, the flag F _A indicating that TA interruption waiting process is completed, it is determined whether it is "1" (step S
1) If F _A ≠ 1, it is determined whether the TA interrupt button on the operation unit 16 is on (step S2). If TA interrupt button is turned off, the same program following buttons in the operation unit 16 a flag F _N indicating that the on state determines whether or not "1" (step S3). If F _N ≠ 1, it is determined whether the same program follow button in the operation unit 16 is turned on (step S4), and if on, the previous flag F _N
It was to "1" (step S5), and subsequently received signal level V _S of the current reception frequency is equal to or less than the first set level V _L (step S6). If V _S ≦ _VL , the continuation time of this state is monitored (step S7), and if the continuation continues for a predetermined time t, the reception frequency is changed to another same network station frequency in accordance with the AF data list described in the memory 15. Switching is performed to select the optimum reception frequency (step S8). If F _N = 1 in step S3, directly go to step S6
The process proceeds to perform a level check of the received signal level V _S of the current reception frequency.

On the other hand, if the TA interrupt button is turned on in step S2, for example, performs a TA interrupt waiting process for controlling the function switching circuit 19 so as to select the audio signal from the tape player 20 (step S9), and the previous flag F _A to "1" (step S10), and subsequently received signal level V _S of the current reception frequency is equal to or less than high second set level V _H than the first set level V _L (step S1
1). If V _S ≦ V _H , the continuation time of this state is monitored (step S12), and after continuing for a predetermined time t, the process proceeds to step S8 to select another same network station frequency according to the AF data list. Perform Steps
If F _A = 1 in S1, the flow directly goes to step S11 to check the level of the reception signal level V _S of the current reception frequency.

That is, in the same program tracking mode in a normal reception state, otherwise identical networks based on AF data list when the received signal level V _S of the current reception frequency is the following states first set level V _L continues for the predetermined time t The reception frequency is switched to the station frequency, and in the TA interrupt standby mode, the reception signal level V _S is set to the second set level V _H (V _H > V _L ).
When the following state continues for a predetermined time t, the reception frequency is switched to another same network station frequency.

Thus, by setting higher than the set level V _L of the set level V _H of the standby mode of TA interrupt during the normal reception, demodulation sensitivity data are demodulated data while the received signal level is high even at low By doing so, accurate demodulated data is always obtained, so that interrupt processing during interrupt standby can always be performed accurately.

In the above-described embodiment, the case of the TA interrupt by the TA data which is the interrupt data has been described. However, the present invention is not limited to this, and PTY (program type) data or M / S
(Music / speech switch) The present invention is also applicable to an interrupt caused by interrupt data such as data.

As described above, according to the control method of the present invention, when the reception signal level is equal to or lower than the second set level higher than the first set level in normal reception in the interrupt standby state, the current reception frequency By switching the reception frequency to another same network station frequency based on the AF data list and selecting the optimum reception frequency, accurate demodulated data can be obtained even if the data demodulation sensitivity is low, so interrupt processing during interrupt standby can be performed. You can always do it accurately.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an RDS receiver to which a control method according to the present invention is applied, FIG. 2 is a flowchart showing a procedure of a control method according to the present invention executed by a processor in a controller of FIG. 1, FIG. 3 is a diagram showing a baseband coding structure of a radio data signal, and FIG.
The figure shows the format of the type OA group. Description of main parts 2... Front end, 4... FM detector 5... Multiplex demodulation circuit 8... Digital PLL circuit 9... Decoder, 14.

 ────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-57-211819 (JP, A) Nikkei Electronics August 24, 1987, pp. 202-217

Claims (1)

(57) [Claims] A control method for a radio data receiver capable of receiving radio data broadcast waves including frequency data of the same network station group and interrupt data indicating the type of program content and having a function of following the same program. In the normal reception mode, when the reception signal level of the current reception frequency is equal to or lower than the first set level, the reception frequency is switched from the current reception frequency to another same network station frequency given by the frequency data to optimize the reception frequency. In the standby mode of the interruption by the interruption data, which performs the optimum reception frequency selection operation for selecting the reception frequency, and waits for the start of the specific program content, the second setting in which the reception signal level is higher than the first setting level Radio data receiver performing the optimum receiving frequency selecting operation when the level is below the level. Control method definitive.