JP2567409B2 - Radio data receiver - Google Patents

Description

TECHNICAL FIELD The present invention relates to a receiver of a radio data system (hereinafter referred to as RDS).
Referred to as a receiver).

BACKGROUND ART Broadcasting-related information such as information related to the program content is transmitted as data at the time of broadcasting from a broadcasting station by multiplex modulation, and the desired program content can be selected on the receiving side based on the demodulated data. In this way, a radio data system (RD that enables the service to be provided to radio listeners
S) there.

In this radio data system, 57KHz which is the third harmonic of the 19KHz stereo pilot signal outside the frequency band of the FM modulation wave is used as the subcarrier, and this subcarrier is filtered and biphase coded. A radio data signal is amplitude-modulated by a data signal indicating information related to broadcasting such as contents, 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 consists of 4 blocks each having 26 bits, and each block consists of a 16-bit information word and a 10-bit check word. In FIG. 4, a block 1 broadcasts a program recognition (PI) code representing a network, a block 2 broadcasts a traffic program recognition (TP) code or a traffic announcement recognition (TA) code, and a block 3 broadcasts the same program. The frequency (AF) data of the network station group, and the program service name information (PS) data such as the broadcasting station name and the network name are arranged in the block 4. 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, and the PS data is transmitted in the type 0A and 0B groups.

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, when one RDS broadcast is received, the network stations that broadcast the same program as described above
Since AF data can be obtained, it is desirable to use this AF data to ensure listening to the same program in a relatively good condition.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a radio data receiver capable of ensuring the listening of the same program in a relatively good state.

A radio data receiver according to the present invention is a radio data receiver provided with a memory storing frequency data of the same network station group, wherein a reception signal level is a first setting level and a second setting level lower than the first setting level. The comparing means for comparing with the set level and the comparing means detects that the received signal level of the broadcast wave of one station in the network station group being received is within the range between the first set level and the second set level. When receiving the frequency data, the frequency data is read from the memory and the reception frequency is switched to the frequency indicated by the frequency data, and the reception signal level is higher than the first set level at the reception frequency switched by the reception frequency switching means. If it is detected by the comparison means, the reception state is continued and the reception signal level is the first level.
If the level is lower than the set level and is detected by the comparison means, the means for returning to the reception of the broadcast wave of the one station being received, and the reception means of the broadcast wave of the one station being received is secondly set by the comparison means. When it is detected that the received frequency is lower than the level, a prohibition unit that prohibits switching of the reception frequency to the frequency indicated by the frequency data stored in the memory is provided.

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

In the RDS receiver to which the present invention shown in FIG. 1 is applied, the FM multiplex broadcast wave received by the antenna 1 is selected by the front end 2 as a desired station and converted to an intermediate frequency (IF), It is supplied to the FM detector 4 via the IF amplifier 3. The front end 2 obtains the local oscillation signal to the mixer 2b by the PLL synthesizer method using the PLL circuit 2a including the programmable frequency divider, and the frequency division ratio of the programmable frequency divider is controlled by the controller 14 described later. By doing so, the channel selection operation is performed. 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 demodulating clock 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 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 demodulation output of the PLL circuit 7 is decoded in synchronization with the clock generated in 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. In the group / block synchronization & error detection circuit 12, the group and block are synchronized based on the 10-bit offset word assigned to the 10-bit checkword of each block, and the 16-bit information is based on the checkword. 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 composed of a microcomputer, and code information of each block in the radio data that is sequentially input in units of groups, that is, radio data information related to the program content of the broadcasting station currently being received (the PI code and AF data described above). , PS data, etc.) and capture it in the memory 15. By this operation, the AF data list f ₁ , f ₂ ... F _{n of the} same network station as the receiving broadcast station is formed.
Further, by controlling the reception frequency data value that determines the frequency division ratio of the programmable frequency divider (not shown) of the PLL circuit 2a forming a part of the front end 2 based on the tuning instruction from the operation unit 16. Perform tuning operation. The reception frequency data value is, for example, the count value of the counter.

On the other hand, when the station detection circuit 20 detects an IF signal of a predetermined level or higher in the IF amplifier 3, the station detection circuit 20 supplies the IF signal to the controller 14 as a reception signal.

The memory 15 is composed of a nonvolatile RAM in which data such as reception frequency data, PI code, AF data, etc. is written, and a ROM in which programs and data are written in advance.

Next, a controller 14 showing the procedure of the control method of the present invention.
The operation of the processor will be described with reference to the flowchart shown in FIG.

The processor executes the same program follow-up routine every predetermined period. In this same program following routine, it is determined whether the flag F is equal to 1 (step 51). The flag F is initialized to 0 when the power is turned on. If F = 0, it is determined whether or not the same program follow button (not shown) of the operation unit 16 has been operated (step 52). When the same program follow button is operated, for example, a predetermined register in the processor is marked as having been operated by the same program follow button by interrupt processing. If the same program follow button has not been operated, this routine ends. on the other hand,
When the operation of the same program follow button is confirmed, flag F is set to 1
Is set (step 53), and it is determined from the output of the station detection circuit 20 whether or not the received signal level V _S of the broadcast wave at the frequency f _{D being} received is below the first set level V ₁ (step 54). . If F = 1 is determined in step 51, the same program following operation is started, so the process immediately proceeds to step 54. If the received signal level V _S is first set level V ₁ or less, the received signal level V _S is determined whether a second set level V ₂ or more further made smaller than the first set level V ₁ (step 55 ). If V ₁ ≧ V _S ≧ V ₂ , it is determined whether the reception state within the level has continued for a predetermined time t or longer (step 56). When the reception state in the range of V ₁ ≧ V _S ≧ V ₂ has not continued for the predetermined time t or longer, the process returns to step 54. However, if the reception state in the range of V ₁ ≧ V _S ≧ V ₂ continues for a predetermined time t or more, the AF data list f ₁ , f written in the memory 15 is written.
₂ ... Reads the AF data f _{AF of} 1 from f _n and sets it in the frequency divider of the PLL circuit 2a (step 57). As a result, the reception frequency changes to the broadcasting frequency of another broadcasting station on the same network. Next, it is determined whether or not the received signal level V _{S at} the new received frequency is less than or equal to the first set level V ₁ (step 58). Received signal level V _S is the first set level V ₁
If it is larger, the reception frequency data in the memory 15 is updated to the AF data f _AF in order to maintain the reception state (step 59), and this routine ends. Therefore, the AF data
The frequency of f _AF becomes a new reception frequency f _D at the next execution of this routine, and the same program following operation is performed. In this case, the AF data is also obtained from f _AF and the new AF data list rewritten in the memory 15 is used. On the other hand, if the received signal level V _S is less than or equal to the first set level V ₁ , the original frequency
In order to return to the reception of the broadcast wave of f _D , the reception frequency data in the memory 15 is read and set in the frequency divider of the PLL circuit 2a (step 60).

On the other hand, if V _S <V ₂ in step 55, it is determined whether or not the reception state has continued for a predetermined time t or longer (step 61). If the reception state of V _S <V ₂ has not continued for the predetermined time t or more, the process returns to step 55, and if the reception state of V _S <V ₂ has continued for the predetermined time t or more, the flag F is reset to 0 ( Step 62) ends this routine.

Therefore, by repeating the processing of this routine at a predetermined cycle, for example, the received signal level V _S of the received broadcast wave at the frequency f _D falls within the range of the first set level V ₁ or less and the second set level V ₂ or more for a predetermined time. AF data list of the same network written in the memory 15 when it decreases for t
AF data of frequency f ₁ is read from f ₁ , f ₂ …… f _n
It is set in the frequency divider of the circuit 2a, and the reception frequency changes to the broadcasting frequency f ₁ of another broadcasting station on the same network. If the reception signal level V _{S at} this new frequency f ₁ is higher than the first set level V ₁ , this reception state is maintained.
However, when the received signal level V _S is equal to or lower than the first set level V ₁ , the reception of the broadcast wave at the original frequency f _D is resumed. Again the received signal level of the received broadcast wave at frequency f _D
If V _S is lowered over a second predetermined level or more ranges in the first set level V ₁ or less for a predetermined time t, AF data list f _1, f ₂ from ...... f _n of the frequency f ₂ AF The data is read and set in the frequency divider of the PLL circuit 2a. That is, f ₁ ,
f ₂ , ... Is smaller than the first set level V ₁ , and the received signal level V _S of the received broadcast wave at the frequency f _D is the first set level.
If remain lowered to the second set level or more range V ₁ or less, the receiving frequency varies as _{f D → f 1 → f D} → f 2 ......, network station group broadcasting station frequency f _D belongs It is repeated until a broadcast wave whose received signal level V _S is higher than the first set level V ₁ is detected. During this repetitive operation, the reception signal level V _S of the reception broadcast wave at the frequency f _D drops below the second set level V ₂ and the reception state continues for a predetermined time t or longer, the flag F is reset to 0. As a result, the same program following operation is completed and the reception frequency becomes frequency f _D
Is maintained.

It should be noted that if a broadcast wave whose received signal level V _S is higher than the first set level V ₁ cannot be detected even if reception is performed at all frequencies from the AF data list frequencies f ₁ to f _n
At 57, the flag F is reset to 0, this routine ends, and the reception state of the frequency f _D is maintained. Further, during the period when the reception frequency changes to the frequency in the AF data list, a mute circuit (not shown) operates to cut off the output of the audio signal, and a broadcast wave whose reception signal level V _S is higher than the first setting level V ₁ When detected, the mute state is released.

Further, the duration of the received signal level V _S is set to be the same as the predetermined time t in steps 56 and 61, but it may be different.

Further, in the embodiment of the present invention described above,
Although the frequency data of the same network station group is stored in the memory by obtaining the AF data from the RDS broadcast wave, even if the frequency data of the same network station group of each receivable broadcasting station is stored in the memory in advance. good.

EFFECTS OF THE INVENTION As described above, in the radio data receiver of the present invention, when the received signal level of the broadcast wave being received falls to a level within the range between the first setting level and the second setting level, the memory is stored. The stored frequency data of the same network station group is read, the reception frequency is switched to the frequency indicated by the read frequency data, and if the reception signal level is higher than the first set level, the reception state is continued, and the reception signal level is If it is below the first set level, the original broadcast wave reception state is restored, and if the reception state is bad again, new frequency data is read and the reception frequency switching is repeated. Therefore, even if the reception condition of the currently received broadcast wave deteriorates, the same program can be listened to in a good reception condition by switching the reception frequency to the frequency of another same network station.

Further, when it is detected that the received signal level of the broadcast wave obtained by the original tuning is equal to or lower than the second set level which is smaller than the first set level, for example, the broadcast station receiving the current signal according to the running of the vehicle. It is considered that the reception frequency is going out of the broadcast coverage area of the network, and switching of the reception frequency to the frequency of another same network station is useless. Therefore,
In this case, switching of the reception frequency is prohibited, so that listening to a desired program can be ensured.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an RDS receiver to which the present invention is applied, FIG. 2 is a flow chart showing an operation of a processor in a controller in the receiver of FIG. 1, and FIG. 3 is a radio data signal. FIG. 4 is a diagram showing a baseband coding structure,
The figure shows the format of a type 0A group. Description of main part symbols 1 ... Antenna 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-56-89123 (JP, A) Nikkei Electronics, August 24, 1987, pages 202-217.

Claims (1)

(57) [Claims] 1. A radio data receiver having a memory storing frequency data of the same network station group, wherein a reception signal level is a first setting level and a second setting level smaller than the first setting level. The comparing means for comparing and the receiving means for receiving a broadcast wave signal level of one station in the network station group being received are within the range between the first setting level and the second setting level. When detected, the frequency data is read from the memory and the reception frequency is switched to the frequency indicated by the frequency data, and the reception signal level is set to the first setting at the reception frequency switched by the reception frequency switching unit. If the comparison means detects that the received signal level is higher than the level, the reception state is continued, and the reception signal level is the first level. Means for returning to the reception of the broadcast wave of the receiving one station if the level is lower than a set level, and the reception signal level of the broadcast wave of the receiving one station by the comparing means is the second A radio data receiver comprising: prohibiting means for prohibiting switching of the reception frequency to a frequency indicated by the frequency data stored in the memory when it is detected that the level is lower than the set level.