JP2569347B2 - 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 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. The radio data signal is amplitude-modulated by a data signal indicating information related to the broadcast such as the content, and the amplitude-modulated subcarrier is frequency-modulated to the 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 in the type 0A 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. In the case of RDS broadcasting, as described above, when one RDS broadcast wave is received, AF data of a group of network stations broadcasting the same program can be obtained. It is possible to switch the reception frequency to another same network station frequency. However, the AF data of the same network station group may include frequencies used by other different network stations, and in such a case, the reception frequency is switched to another same network station frequency. May not be done quickly.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and when the reception state of a broadcast wave being received is getting worse, the reception frequency is switched to the same network station frequency where another reception state is good. Is to provide a radio data receiver that can quickly perform the operation.

The radio data receiver of the present invention is a radio data receiver capable of receiving radio data broadcast waves including program recognition data representing a network and a frequency data list of the same network station group and having a function of following the same program. Switching means for sequentially switching the reception frequency to the frequency given by the frequency data from the frequency data list when the same program follow-up command is issued; and the reception frequency switched each time the reception frequency is switched by the switching means. A first discriminating means for discriminating whether or not the receiving condition is good, and program recognition data obtained from the received broadcast wave at a frequency determined by the first discriminating device to be good. Second determining means for determining whether or not the program recognition data matches the program recognition data; Means for setting the reception frequency to the frequency of the broadcast wave determined to be coincident when determined, and switching means for determining the reception frequency based on the frequency data list by the second determination means of the frequency data used for switching the reception frequency. Detecting means for detecting frequency data excluding frequency data when program recognition data mismatch is determined, wherein the switching means detects the frequency data after switching to all frequency data in the list. The receiving frequency is sequentially switched to the frequency given by the frequency data.

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

In FIG. 1 showing an example of the configuration of an RDS receiver according to the present invention, an FM multiplex broadcast wave received by an antenna 1 is selected by a front end 2 and converted into an intermediate frequency (IF). The signal is supplied to the FM detector 4 via the IF amplifier 3. 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, and in the case of a stereo broadcast, is separated into L (left) and R (right) channel audio signals to be reproduced audio output. The muting circuit 20 is on / off controlled 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 16-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 tuning operation is performed by controlling the reception frequency data value that determines the frequency ratio.

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 18 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 is within a predetermined level range. The received signal level detected by the level detection circuit 17 and the station detection signal output from the station detection circuit 18 are provided by the controller.
Supplied to 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 FIG.
Description will be made according to the flowchart shown in FIG. Note that the first storage area of the memory 15, n pieces of AF data list f ₁ of incorporated AF data obtained by demodulating the received broadcast the same network station and a broadcast station being currently received, f ₂ ...
It is assumed that f _n is already stored.

The processor first determines whether the reception state of the broadcast wave by the current reception frequency is deteriorated by the reception signal level V _S from the level detection circuit 17 monitors whether the set level V _O or less (step S1 ), If V _S ≦ V _O , the reception state has deteriorated, and it is determined whether or not the AF data list exists in the memory 15 (step S2). If the AF data list exists, the same program tracking mode is set, and PI data and the AF data obtained from the currently received broadcast wave are fetched and held in a register or the like (step S3). continue,
The variable M is made equal to 0 and the variable N is made equal to 1 (step S4).
Read AF data f _N from the memory 15 (step S5), and performs the tuning operation by outputting the AF data in the PLL circuit in the front-end 2 (not shown) (step S6). Then, the reception signal level V _S obtained from the level detecting circuit 17 determines whether or not exceeds the set level V _O (step S7), and if V _S> V _O, PI data representing the network of the reception station (Step S
8) It is determined whether this PI data matches the PI data held in the register or the like (step S9).

If it is determined that V _S ≦ V _O at step S7, or if the PI data is determined to match in step S9, and adds 1 to the variable M (step S10), and the AF data of the read N program memory 15 Is written to the M-th position of the second storage area different from the first storage area already stored (step S11), and the AF stored in the first storage area of the memory 15 is written.
Whether all data has been read (N = n or not)
Is determined (step S12). On the other hand, if it is determined in step S9 that the PI data does not match, another different network broadcast wave has been received. In this case, the process immediately proceeds to step S12, and writing to the second storage area is not performed. If it is determined in step S12 that all AF data has not been read (N <n), 1 is added to the variable N (step S13), and the process returns to step S5 to read new AF data from the first storage area. Memory 15
After reading out all the AF data from the first storage area, a timer (not shown) sets a predetermined time T (for example, 60 seconds).
Set c) to start time measurement (step S14),
The variable N is made equal to 1 (step S15). Then, the N-th AF data in the second storage area of the memory 15 is read (step S16), and this AF data is
The tuning operation is performed by outputting to the LL circuit (step S17). Next, it is determined whether or not the received signal level V _S obtained from the level detection circuit 17 exceeds the set level V _O (step S18). If V _S > V _O , PI data representing the network of the receiving station is determined. Import (step
S19), it is determined whether or not the fetched PI data matches the PI data held in the register or the like (step S2).
0). If V _S ≦ V _O , or even if V _S > V _O , step S20
If it is determined that the PI data does not match in
It is determined whether or not all the AF data stored in the second storage area has been read (whether or not N = M) (step
S21). If it is determined that all the AF data has not been read from the second storage area (N <M), 1 is added to the variable N (step S22), and the process returns to step S16 to return to the second
Read the Nth AF data in the storage area. On the other hand, the second
If it is determined that all the AF data has been read from the storage area, it is determined whether or not the timer has completed the time measurement of the predetermined time T (step S23). If the timer has not completed the time measurement, the process returns to step S15 to repeat the selection of the same network station having a good reception state according to the AF data list in the second storage area. When the timer completes the time measurement, it is determined that it is impossible to select the same network station having a good reception state at the present time, and this routine is terminated to return to the reception frequency immediately before the start of the same program tracking mode. .

If it is determined in step S20 that the PI data matches, the mode shifts to the normal reception mode using the same network station frequency currently being received as the reception frequency.

As described above, in the same program tracking mode, first, the AF data obtained from the received broadcast wave and stored in the first storage area of the memory 15 is sequentially read out, and the frequency given by the AF data becomes the reception frequency. And the received signal level V _S
AF data in the memory 15 but the set level V _O less had been AF data and the reception signal level V _S exceeds the set level V _O and network station which has been received until the same program following mode immediately before the start and the PI data coincide AF data that has been written to the second storage area and the PI data did not match is not written to the second storage area. Next, the AF data written in the second storage area of the memory 15 is sequentially read out, and the frequency given by the AF data becomes the reception frequency. Until the predetermined time T elapses, the AF data is repeatedly and sequentially repeated from the second storage area until the reception signal level V _S exceeds the set level V _O and the frequency given by the AF data with the matching PI data becomes the reception frequency. It is read.

In the above-described embodiment, even if V _S > V _O in step S7 and the PI data matches in step S9, all the AF data in the first storage area are read, and the reception frequency is set in accordance with the AF data. Then, the process proceeds to step S13. In such a case, as shown in FIG. 2 (c), the same program follow-up mode is terminated, and the frequency given by the AF data whose PI data coincides is set as the reception frequency. May be returned to the receiving mode.

Also, becomes the same program following mode automatically same program follow command when the received signal level V _S falls below the set level V _O occurs in the embodiment described above, the same program followed by a button operation or the like by the user The present invention can be applied to a case where a command is issued and the same program tracking mode is set.

As described above, in the radio data receiver of the present invention, when the same program follow-up command is issued due to the deterioration of the reception state of the broadcast wave at the current reception frequency, the AF data from the frequency data list is used. Check the reception status and PI data by switching the reception frequency to the given frequency, and after switching the reception frequency by all the frequency data in the frequency data list, the PI data matches the received broadcast wave data Ignore AF data that does not
The reception frequency is switched to a frequency given only by the AF data to search for a broadcast wave of the same network station in a good reception state. Therefore, even if the AF data of the same network station group contains frequencies used by other different network stations, the AF data of the different network stations are eliminated early, so that the same program can be read with almost no discomfort. It is possible to quickly switch to a broadcast wave that can be heard in a good reception state.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an RDS receiver to which the present invention is applied, and FIGS. 2 (a), (b) and (c) show a control procedure executed by a processor in a controller of FIG. FIG. 3 is a diagram showing a baseband coding structure of a radio data signal, and FIG.
It is a figure showing the format of an OA group. Explanation of Signs of Main Part 2 Front End 4 FM Detector 5 Multiplex Demodulation Circuit 8 Digital PLL Circuit 9 Decoder 14 Controller

Continuation of the front page (56) References JP-A-60-132426 (JP, A) Nikkei Electronics August 24, 1987, pp. 202-217

Claims (1)

(57) [Claims] 1. Program recognition data representing a network;
A radio data receiver capable of receiving a radio data broadcast wave including a frequency data list of the same network station group and having a function of following the same program, wherein when the same program following command is issued, Switching means for sequentially switching the reception frequency to a frequency given by the frequency data, and whenever the reception frequency is switched by the switching means, determining whether the reception state at the switched reception frequency is good or not. Determining means for determining whether or not program recognition data obtained from a received broadcast wave at a frequency determined by the first determining means to be in a good reception state matches predetermined program recognition data; Discriminating means; and a frequency of the broadcast wave determined to be coincident with the program discriminating data when coincidence is determined by the second discriminating means. Means for setting a reception frequency, and when the discrimination of the program recognition data is discriminated by the second discrimination means among the frequency data used for the reception frequency switching based on the frequency data list by the switching means. Detecting means for detecting frequency data excluding frequency data, wherein the switching means, after switching to all the frequency data in the frequency data list, a frequency given by the frequency data detected by the detecting means. A radio data receiver characterized by sequentially switching a receiving frequency.